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Petrovszki D, Valkai S, Kelemen L, Nagy L, Agarwal V, Krekic S, Zimányi L, Dér A. Microsecond All-Optical Modulation by Biofunctionalized Porous Silicon Microcavity. Nanomaterials (Basel) 2023; 13:2070. [PMID: 37513080 PMCID: PMC10385878 DOI: 10.3390/nano13142070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 07/11/2023] [Accepted: 07/12/2023] [Indexed: 07/30/2023]
Abstract
We successfully created a composite photonic structure out of porous silicon (PSi) microcavities doped by the photochromic protein, photoactive yellow protein (PYP). Massive incorporation of the protein molecules into the pores was substantiated by a 30 nm shift of the resonance dip upon functionalization, and light-induced reflectance changes of the device due to the protein photocycle were recorded. Model calculations for the photonic properties of the device were consistent with earlier results on the nonlinear optical properties of the protein, whose degree of incorporation into the PSi structure was also estimated. The successful proof-of-concept results are discussed in light of possible practical applications in the future.
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Affiliation(s)
- Dániel Petrovszki
- Institute of Biophysics, Biological Research Centre, Eötvös Loránd Research Network, 6726 Szeged, Hungary
- Doctoral School of Multidisciplinary Medical Science, University of Szeged, 6720 Szeged, Hungary
| | - Sándor Valkai
- Institute of Biophysics, Biological Research Centre, Eötvös Loránd Research Network, 6726 Szeged, Hungary
| | - Lóránd Kelemen
- Institute of Biophysics, Biological Research Centre, Eötvös Loránd Research Network, 6726 Szeged, Hungary
| | - László Nagy
- Department of Medical Physics and Informatics, Faculty of Science and Informatics, Albert Szent-Györgyi Medical School, University of Szeged, 6720 Szeged, Hungary
- Institute of Plant Biology, Biological Research Centre, Eötvös Loránd Research Network, 6726 Szeged, Hungary
| | - Vivechana Agarwal
- Centro de Investigación en Ingeniería y Ciencias Aplicadas-IICBA, Universidad Autónoma del Estado de Morelos, Cuernavaca 62209, Morelos, Mexico
| | - Szilvia Krekic
- Institute of Biophysics, Biological Research Centre, Eötvös Loránd Research Network, 6726 Szeged, Hungary
- Doctoral School of Multidisciplinary Medical Science, University of Szeged, 6720 Szeged, Hungary
| | - László Zimányi
- Institute of Biophysics, Biological Research Centre, Eötvös Loránd Research Network, 6726 Szeged, Hungary
| | - András Dér
- Institute of Biophysics, Biological Research Centre, Eötvös Loránd Research Network, 6726 Szeged, Hungary
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2
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Veszelka S, Mészáros M, Porkoláb G, Szecskó A, Kondor N, Ferenc G, Polgár TF, Katona G, Kóta Z, Kelemen L, Páli T, Vigh JP, Walter FR, Bolognin S, Schwamborn JC, Jan JS, Deli MA. A Triple Combination of Targeting Ligands Increases the Penetration of Nanoparticles across a Blood-Brain Barrier Culture Model. Pharmaceutics 2021; 14:pharmaceutics14010086. [PMID: 35056983 PMCID: PMC8778049 DOI: 10.3390/pharmaceutics14010086] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 12/17/2021] [Accepted: 12/21/2021] [Indexed: 12/30/2022] Open
Abstract
Nanosized drug delivery systems targeting transporters of the blood-brain barrier (BBB) are promising carriers to enhance the penetration of therapeutics into the brain. The expression of solute carriers (SLC) is high and shows a specific pattern at the BBB. Here we show that targeting ligands ascorbic acid, leucine and glutathione on nanoparticles elevated the uptake of albumin cargo in cultured primary rat brain endothelial cells. Moreover, we demonstrated the ability of the triple-targeted nanovesicles to deliver their cargo into midbrain organoids after crossing the BBB model. The cellular uptake was temperature- and energy-dependent based on metabolic inhibition. The process was decreased by filipin and cytochalasin D, indicating that the cellular uptake of nanoparticles was partially mediated by endocytosis. The uptake of the cargo encapsulated in triple-targeted nanoparticles increased after modification of the negative zeta potential of endothelial cells by treatment with a cationic lipid or after cleaving the glycocalyx with an enzyme. We revealed that targeted nanoparticles elevated plasma membrane fluidity, indicating the fusion of nanovesicles with endothelial cell membranes. Our data indicate that labeling nanoparticles with three different ligands of multiple transporters of brain endothelial cells can promote the transfer and delivery of molecules across the BBB.
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Affiliation(s)
- Szilvia Veszelka
- Biological Research Centre, Institute of Biophysics, Eötvös Loránd Research Network, Temesvári krt. 62, H-6726 Szeged, Hungary; (M.M.); (G.P.); (A.S.); (N.K.); (T.F.P.); (Z.K.); (L.K.); (T.P.); (J.P.V.); (F.R.W.)
- Correspondence: (S.V.); (M.A.D.)
| | - Mária Mészáros
- Biological Research Centre, Institute of Biophysics, Eötvös Loránd Research Network, Temesvári krt. 62, H-6726 Szeged, Hungary; (M.M.); (G.P.); (A.S.); (N.K.); (T.F.P.); (Z.K.); (L.K.); (T.P.); (J.P.V.); (F.R.W.)
| | - Gergő Porkoláb
- Biological Research Centre, Institute of Biophysics, Eötvös Loránd Research Network, Temesvári krt. 62, H-6726 Szeged, Hungary; (M.M.); (G.P.); (A.S.); (N.K.); (T.F.P.); (Z.K.); (L.K.); (T.P.); (J.P.V.); (F.R.W.)
- Doctoral School of Biology, University of Szeged, Dugonics tér 13, H-6720 Szeged, Hungary
| | - Anikó Szecskó
- Biological Research Centre, Institute of Biophysics, Eötvös Loránd Research Network, Temesvári krt. 62, H-6726 Szeged, Hungary; (M.M.); (G.P.); (A.S.); (N.K.); (T.F.P.); (Z.K.); (L.K.); (T.P.); (J.P.V.); (F.R.W.)
| | - Nóra Kondor
- Biological Research Centre, Institute of Biophysics, Eötvös Loránd Research Network, Temesvári krt. 62, H-6726 Szeged, Hungary; (M.M.); (G.P.); (A.S.); (N.K.); (T.F.P.); (Z.K.); (L.K.); (T.P.); (J.P.V.); (F.R.W.)
| | - Györgyi Ferenc
- Biological Research Centre, Institute of Plant Biology, Eötvös Loránd Research Network, Temesvári krt. 62, H-6726 Szeged, Hungary;
| | - Tamás F. Polgár
- Biological Research Centre, Institute of Biophysics, Eötvös Loránd Research Network, Temesvári krt. 62, H-6726 Szeged, Hungary; (M.M.); (G.P.); (A.S.); (N.K.); (T.F.P.); (Z.K.); (L.K.); (T.P.); (J.P.V.); (F.R.W.)
| | - Gábor Katona
- Faculty of Pharmacy, Institute of Pharmaceutical Technology and Regulatory Affairs, University of Szeged, Eötvös u. 6, H-6720 Szeged, Hungary;
| | - Zoltán Kóta
- Biological Research Centre, Institute of Biophysics, Eötvös Loránd Research Network, Temesvári krt. 62, H-6726 Szeged, Hungary; (M.M.); (G.P.); (A.S.); (N.K.); (T.F.P.); (Z.K.); (L.K.); (T.P.); (J.P.V.); (F.R.W.)
| | - Lóránd Kelemen
- Biological Research Centre, Institute of Biophysics, Eötvös Loránd Research Network, Temesvári krt. 62, H-6726 Szeged, Hungary; (M.M.); (G.P.); (A.S.); (N.K.); (T.F.P.); (Z.K.); (L.K.); (T.P.); (J.P.V.); (F.R.W.)
| | - Tibor Páli
- Biological Research Centre, Institute of Biophysics, Eötvös Loránd Research Network, Temesvári krt. 62, H-6726 Szeged, Hungary; (M.M.); (G.P.); (A.S.); (N.K.); (T.F.P.); (Z.K.); (L.K.); (T.P.); (J.P.V.); (F.R.W.)
| | - Judit P. Vigh
- Biological Research Centre, Institute of Biophysics, Eötvös Loránd Research Network, Temesvári krt. 62, H-6726 Szeged, Hungary; (M.M.); (G.P.); (A.S.); (N.K.); (T.F.P.); (Z.K.); (L.K.); (T.P.); (J.P.V.); (F.R.W.)
- Doctoral School of Biology, University of Szeged, Dugonics tér 13, H-6720 Szeged, Hungary
| | - Fruzsina R. Walter
- Biological Research Centre, Institute of Biophysics, Eötvös Loránd Research Network, Temesvári krt. 62, H-6726 Szeged, Hungary; (M.M.); (G.P.); (A.S.); (N.K.); (T.F.P.); (Z.K.); (L.K.); (T.P.); (J.P.V.); (F.R.W.)
| | - Silvia Bolognin
- Luxembourg Centre for Systems Biomedicine (LCSB), Developmental and Cellular Biology, University of Luxembourg, 4365 Belvaux, Luxembourg; (S.B.); (J.C.S.)
| | - Jens C. Schwamborn
- Luxembourg Centre for Systems Biomedicine (LCSB), Developmental and Cellular Biology, University of Luxembourg, 4365 Belvaux, Luxembourg; (S.B.); (J.C.S.)
| | - Jeng-Shiung Jan
- Department of Chemical Engineering, National Cheng Kung University, Tainan 70101, Taiwan;
| | - Mária A. Deli
- Biological Research Centre, Institute of Biophysics, Eötvös Loránd Research Network, Temesvári krt. 62, H-6726 Szeged, Hungary; (M.M.); (G.P.); (A.S.); (N.K.); (T.F.P.); (Z.K.); (L.K.); (T.P.); (J.P.V.); (F.R.W.)
- Correspondence: (S.V.); (M.A.D.)
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Kubacková J, Slabý C, Horvath D, Hovan A, Iványi GT, Vizsnyiczai G, Kelemen L, Žoldák G, Tomori Z, Bánó G. Assessing the Viscoelasticity of Photopolymer Nanowires Using a Three-Parameter Solid Model for Bending Recovery Motion. Nanomaterials (Basel) 2021; 11:2961. [PMID: 34835725 PMCID: PMC8618069 DOI: 10.3390/nano11112961] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 10/27/2021] [Accepted: 11/01/2021] [Indexed: 12/26/2022]
Abstract
Photopolymer nanowires prepared by two-photon polymerization direct laser writing (TPP-DLW) are the building blocks of many microstructure systems. These nanowires possess viscoelastic characteristics that define their deformations under applied forces when operated in a dynamic regime. A simple mechanical model was previously used to describe the bending recovery motion of deflected nanowire cantilevers in Newtonian liquids. The inverse problem is targeted in this work; the experimental observations are used to determine the nanowire physical characteristics. Most importantly, based on the linear three-parameter solid model, we derive explicit formulas to calculate the viscoelastic material parameters. It is shown that the effective elastic modulus of the studied nanowires is two orders of magnitude lower than measured for the bulk material. Additionally, we report on a notable effect of the surrounding aqueous glucose solution on the elasticity and the intrinsic viscosity of the studied nanowires made of Ormocomp.
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Affiliation(s)
- Jana Kubacková
- Department of Biophysics, Institute of Experimental Physics SAS, Watsonova 47, 040 01 Košice, Slovakia; (J.K.); (Z.T.)
| | - Cyril Slabý
- Department of Biophysics, Faculty of Science, P. J. Šafárik University, Jesenná 5, 041 54 Košice, Slovakia; (C.S.); (A.H.)
| | - Denis Horvath
- Center for Interdisciplinary Biosciences, Technology and Innovation Park, P. J. Šafárik University, Jesenná 5, 041 54 Košice, Slovakia; (D.H.); (G.Ž.)
| | - Andrej Hovan
- Department of Biophysics, Faculty of Science, P. J. Šafárik University, Jesenná 5, 041 54 Košice, Slovakia; (C.S.); (A.H.)
| | - Gergely T. Iványi
- Faculty of Science and Informatics, University of Szeged, Dugonics Square 13, 6720 Szeged, Hungary;
- Biological Research Centre, Institute of Biophysics, Eötvös Loránd Research Network (ELKH), Temesvári krt. 62, 6726 Szeged, Hungary; (G.V.); (L.K.)
| | - Gaszton Vizsnyiczai
- Biological Research Centre, Institute of Biophysics, Eötvös Loránd Research Network (ELKH), Temesvári krt. 62, 6726 Szeged, Hungary; (G.V.); (L.K.)
| | - Lóránd Kelemen
- Biological Research Centre, Institute of Biophysics, Eötvös Loránd Research Network (ELKH), Temesvári krt. 62, 6726 Szeged, Hungary; (G.V.); (L.K.)
| | - Gabriel Žoldák
- Center for Interdisciplinary Biosciences, Technology and Innovation Park, P. J. Šafárik University, Jesenná 5, 041 54 Košice, Slovakia; (D.H.); (G.Ž.)
| | - Zoltán Tomori
- Department of Biophysics, Institute of Experimental Physics SAS, Watsonova 47, 040 01 Košice, Slovakia; (J.K.); (Z.T.)
| | - Gregor Bánó
- Department of Biophysics, Faculty of Science, P. J. Šafárik University, Jesenná 5, 041 54 Košice, Slovakia; (C.S.); (A.H.)
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Fekete T, Mészáros M, Szegletes Z, Vizsnyiczai G, Zimányi L, Deli MA, Veszelka S, Kelemen L. Optically Manipulated Microtools to Measure Adhesion of the Nanoparticle-Targeting Ligand Glutathione to Brain Endothelial Cells. ACS Appl Mater Interfaces 2021; 13:39018-39029. [PMID: 34397215 DOI: 10.1021/acsami.1c08454] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Targeting nanoparticles as drug delivery platforms is crucial to facilitate their cellular entry. Docking of nanoparticles by targeting ligands on cell membranes is the first step for the initiation of cellular uptake. As a model system, we studied brain microvascular endothelial cells, which form the anatomical basis of the blood-brain barrier, and the tripeptide glutathione, one of the most effective targeting ligands of nanoparticles to cross the blood-brain barrier. To investigate this initial docking step between glutathione and the membrane of living brain endothelial cells, we applied our recently developed innovative optical method. We present a microtool, with a task-specific geometry used as a probe, actuated by multifocus optical tweezers to characterize the adhesion probability and strength of glutathione-coated surfaces to the cell membrane of endothelial cells. The binding probability of the glutathione-coated surface and the adhesion force between the microtool and cell membrane was measured in a novel arrangement: cells were cultured on a vertical polymer wall and the mechanical forces were generated laterally and at the same time, perpendicularly to the plasma membrane. The adhesion force values were also determined with more conventional atomic force microscopy (AFM) measurements using functionalized colloidal probes. The optical trapping-based method was found to be suitable to measure very low adhesion forces (≤ 20 pN) without a high level of noise, which is characteristic for AFM measurements in this range. The holographic optical tweezers-directed functionalized microtools may help characterize the adhesion step of nanoparticles initiating transcytosis and select ligands to target nanoparticles.
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Affiliation(s)
- Tamás Fekete
- Institute of Biophysics, Biological Research Centre, Eötvös Loránd Research Network (ELKH), Szeged 6726, Hungary
- Doctoral School in Multidisciplinary Medicine, University of Szeged, Szeged 6720, Hungary
| | - Mária Mészáros
- Institute of Biophysics, Biological Research Centre, Eötvös Loránd Research Network (ELKH), Szeged 6726, Hungary
| | - Zsolt Szegletes
- Institute of Biophysics, Biological Research Centre, Eötvös Loránd Research Network (ELKH), Szeged 6726, Hungary
| | - Gaszton Vizsnyiczai
- Institute of Biophysics, Biological Research Centre, Eötvös Loránd Research Network (ELKH), Szeged 6726, Hungary
| | - László Zimányi
- Institute of Biophysics, Biological Research Centre, Eötvös Loránd Research Network (ELKH), Szeged 6726, Hungary
| | - Mária A Deli
- Institute of Biophysics, Biological Research Centre, Eötvös Loránd Research Network (ELKH), Szeged 6726, Hungary
| | - Szilvia Veszelka
- Institute of Biophysics, Biological Research Centre, Eötvös Loránd Research Network (ELKH), Szeged 6726, Hungary
| | - Lóránd Kelemen
- Institute of Biophysics, Biological Research Centre, Eötvös Loránd Research Network (ELKH), Szeged 6726, Hungary
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Taneva SG, Krumova S, Bogár F, Kincses A, Stoichev S, Todinova S, Danailova A, Horváth J, Násztor Z, Kelemen L, Dér A. Insights into graphene oxide interaction with human serum albumin in isolated state and in blood plasma. Int J Biol Macromol 2021; 175:19-29. [PMID: 33508363 DOI: 10.1016/j.ijbiomac.2021.01.151] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 01/21/2021] [Accepted: 01/21/2021] [Indexed: 11/18/2022]
Abstract
The interactions of graphene oxide (GO), a 2-dimensional nanomaterial with hydrophilic edges, hydrophobic basal plane and large flat surfaces, with biological macromolecules, are of key importance for the development of novel nanomaterials for biomedical applications. To gain more insight into the interaction of GO flakes with human serum albumin (HSA), we examined GO binding to HSA in its isolated state and in blood plasma. Calorimetric data reveal that GO strongly stabilizes free isolated HSA against a thermal challenge at low ionic strength, indicating strong binding interactions, confirmed by the drop in ζ-potential of the HSA/GO assemblies compared to bare GO flakes. However, calorimetry also revealed that the HSA-GO molecular interaction is hampered in blood plasma, the ionic strength being particularly important for the interactions. Molecular modelling calculations are in full concert with these experimental findings, indicating a considerably higher binding affinity for HSA to GO in its partially unfolded state, characteristic to low-ionic-strength environment, than for the native protein conformation, observed under physiological conditions. Therefore, for the first time we demonstrate an impeded interaction between HSA and GO nanoflakes in blood plasma, and suggest that the protein is protected from the plausible toxic effects of GO under native conditions.
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Affiliation(s)
- Stefka G Taneva
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl.21, 1113 Sofia, Bulgaria.
| | - Sashka Krumova
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl.21, 1113 Sofia, Bulgaria
| | - Ferenc Bogár
- Department of Medical Chemistry, University of Szeged, H-6720 Szeged, Hungary; MTA-SZTE Biomimetic Systems Research Group, University of Szeged, H-6720 Szeged, Hungary
| | - András Kincses
- Institute of Biophysics, Biological Research Centre, H-6726 Szeged, Hungary
| | - Svetozar Stoichev
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl.21, 1113 Sofia, Bulgaria
| | - Svetla Todinova
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl.21, 1113 Sofia, Bulgaria
| | - Avgustina Danailova
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl.21, 1113 Sofia, Bulgaria
| | - János Horváth
- Institute of Biophysics, Biological Research Centre, H-6726 Szeged, Hungary; Doctoral School of Physics, University of Szeged, H-6720 Szeged, Hungary
| | - Zoltán Násztor
- Institute of Biophysics, Biological Research Centre, H-6726 Szeged, Hungary
| | - Lóránd Kelemen
- Institute of Biophysics, Biological Research Centre, H-6726 Szeged, Hungary
| | - András Dér
- Institute of Biophysics, Biological Research Centre, H-6726 Szeged, Hungary
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Grexa I, Fekete T, Molnár J, Molnár K, Vizsnyiczai G, Ormos P, Kelemen L. Single-Cell Elasticity Measurement with an Optically Actuated Microrobot. Micromachines (Basel) 2020; 11:mi11090882. [PMID: 32972024 PMCID: PMC7570390 DOI: 10.3390/mi11090882] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 09/15/2020] [Accepted: 09/20/2020] [Indexed: 02/07/2023]
Abstract
A cell elasticity measurement method is introduced that uses polymer microtools actuated by holographic optical tweezers. The microtools were prepared with two-photon polymerization. Their shape enables the approach of the cells in any lateral direction. In the presented case, endothelial cells grown on vertical polymer walls were probed by the tools in a lateral direction. The use of specially shaped microtools prevents the target cells from photodamage that may arise during optical trapping. The position of the tools was recorded simply with video microscopy and analyzed with image processing methods. We critically compare the resulting Young’s modulus values to those in the literature obtained by other methods. The application of optical tweezers extends the force range available for cell indentations measurements down to the fN regime. Our approach demonstrates a feasible alternative to the usual vertical indentation experiments.
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Affiliation(s)
- István Grexa
- Biological Research Centre, Temesvári krt. 62, 6726 Szeged, Hungary; (I.G.); (T.F.); (J.M.); (K.M.); (G.V.); (P.O.)
- Doctoral School of Interdisciplinary Medicine, University of Szeged, Korányi fasor 10, 6720 Szeged, Hungary
| | - Tamás Fekete
- Biological Research Centre, Temesvári krt. 62, 6726 Szeged, Hungary; (I.G.); (T.F.); (J.M.); (K.M.); (G.V.); (P.O.)
- Doctoral School of Multidisciplinary Medicine, Dóm tér 9, Hungary University of Szeged, 6720 Szeged, Hungary
| | - Judit Molnár
- Biological Research Centre, Temesvári krt. 62, 6726 Szeged, Hungary; (I.G.); (T.F.); (J.M.); (K.M.); (G.V.); (P.O.)
| | - Kinga Molnár
- Biological Research Centre, Temesvári krt. 62, 6726 Szeged, Hungary; (I.G.); (T.F.); (J.M.); (K.M.); (G.V.); (P.O.)
- Doctoral School of Theoretical Medicine, University of Szeged, Korányi fasor 10, 6720 Szeged, Hungary
| | - Gaszton Vizsnyiczai
- Biological Research Centre, Temesvári krt. 62, 6726 Szeged, Hungary; (I.G.); (T.F.); (J.M.); (K.M.); (G.V.); (P.O.)
| | - Pál Ormos
- Biological Research Centre, Temesvári krt. 62, 6726 Szeged, Hungary; (I.G.); (T.F.); (J.M.); (K.M.); (G.V.); (P.O.)
| | - Lóránd Kelemen
- Biological Research Centre, Temesvári krt. 62, 6726 Szeged, Hungary; (I.G.); (T.F.); (J.M.); (K.M.); (G.V.); (P.O.)
- Correspondence: ; Tel.: +36-62-599-600 (ext. 419)
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Andreeva TD, Dér A, Kelemen L, Krastev R, Taneva SG. Modulation of the internal structure and surface properties of natural and synthetic polymer matrices by graphene oxide doping. POLYM ADVAN TECHNOL 2020. [DOI: 10.1002/pat.4885] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Tonya D. Andreeva
- Institute of Biophysics and Biomedical EngineeringBulgarian Academy of Sciences Sofia Bulgaria
- Reutlingen UniversityFaculty of Applied Chemistry Reutlingen Germany
| | - András Dér
- Biological Research Centre of the Hungarian Academy of SciencesInstitute of Biophysics Szeged Hungary
| | - Lóránd Kelemen
- Biological Research Centre of the Hungarian Academy of SciencesInstitute of Biophysics Szeged Hungary
| | - Rumen Krastev
- Reutlingen UniversityFaculty of Applied Chemistry Reutlingen Germany
- Department “Biomaterials”The Natural and Medical Sciences Institute at the University of Tübingen (NMI) Reutlingen Germany
| | - Stefka G. Taneva
- Institute of Biophysics and Biomedical EngineeringBulgarian Academy of Sciences Sofia Bulgaria
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Vizsnyiczai G, Búzás A, Lakshmanrao Aekbote B, Fekete T, Grexa I, Ormos P, Kelemen L. Multiview microscopy of single cells through microstructure-based indirect optical manipulation. Biomed Opt Express 2020; 11:945-962. [PMID: 32133231 PMCID: PMC7041459 DOI: 10.1364/boe.379233] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 12/16/2019] [Accepted: 12/16/2019] [Indexed: 05/08/2023]
Abstract
Fluorescent observation of cells generally suffers from the limited axial resolution due to the elongated point spread function of the microscope optics. Consequently, three-dimensional imaging results in axial resolution that is several times worse than the transversal. The optical solutions to this problem usually require complicated optics and extreme spatial stability. A straightforward way to eliminate anisotropic resolution is to fuse images recorded from multiple viewing directions achieved mostly by the mechanical rotation of the entire sample. In the presented approach, multiview imaging of single cells is implemented by rotating them around an axis perpendicular to the optical axis by means of holographic optical tweezers. For this, the cells are indirectly trapped and manipulated with special microtools made with two-photon polymerization. The cell is firmly attached to the microtool and is precisely manipulated with 6 degrees of freedom. The total control over the cells' position allows for its multiview fluorescence imaging from arbitrarily selected directions. The image stacks obtained this way are combined into one 3D image array with a multiview image processing pipeline resulting in isotropic optical resolution that approaches the lateral diffraction limit. The presented tool and manipulation scheme can be readily applied in various microscope platforms.
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Affiliation(s)
- Gaszton Vizsnyiczai
- Institute of Biophysics, Biological Research Centre, Temesvári krt. 62, Szeged, 6726, Hungary
- Doctoral School of Physics, Faculty of Science and Informatics, University of Szeged, Dugonics square 13, Szeged, 6720, Hungary
| | - András Búzás
- Institute of Biophysics, Biological Research Centre, Temesvári krt. 62, Szeged, 6726, Hungary
- Doctoral School of Physics, Faculty of Science and Informatics, University of Szeged, Dugonics square 13, Szeged, 6720, Hungary
| | - Badri Lakshmanrao Aekbote
- Institute of Biophysics, Biological Research Centre, Temesvári krt. 62, Szeged, 6726, Hungary
- School of Engineering, James Watt South Building, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Tamás Fekete
- Institute of Biophysics, Biological Research Centre, Temesvári krt. 62, Szeged, 6726, Hungary
- Doctoral School of Multidisciplinary Medical Sciences, Faculty of Medicine, University of Szeged, Dugonics square 13, Szeged, 6720, Hungary
| | - István Grexa
- Institute of Biophysics, Biological Research Centre, Temesvári krt. 62, Szeged, 6726, Hungary
- Doctoral School of Interdisciplinary Medicine, Faculty of Medicine, University of Szeged, Dugonics square 13, Szeged, 6720, Hungary
| | - Pál Ormos
- Institute of Biophysics, Biological Research Centre, Temesvári krt. 62, Szeged, 6726, Hungary
| | - Lóránd Kelemen
- Institute of Biophysics, Biological Research Centre, Temesvári krt. 62, Szeged, 6726, Hungary
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9
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Kelemen L, Lepera E, Horváth B, Ormos P, Osellame R, Martínez Vázquez R. Direct writing of optical microresonators in a lab-on-a-chip for label-free biosensing. Lab Chip 2019; 19:1985-1990. [PMID: 31044200 DOI: 10.1039/c9lc00174c] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Whispering gallery mode (WGM) resonators are promising optical structures for microfluidic label-free biosensors mainly due to their high sensitivity, but from a practical point of view they present numerous constraints that make their use in real laboratory diagnosis application difficult. Herein we report on a monolithic lab on a chip fabricated by a hybrid femtosecond laser micromachining approach, for label-free biosensing. It consists of a polymer WGM microresonator sensor integrated inside a glass microfluidic chip, presenting a refractive index change sensitivity of 61 nm per RIU. The biosensing capabilities of the device have been demonstrated by exploiting the biotin-streptavidin binding affinity, obtaining a measurable minimum surface density increase of 67 × 103 molecules per μm2.
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Affiliation(s)
- L Kelemen
- Biological Research Centre, Institute of Biophysics, Hungarian Academy of Sciences, Temesvári krt. 62, 6726 Szeged, Hungary
| | - E Lepera
- Institute for Photonics and Nanotechnologies, National Research Council, Piazza Leonardo da Vinci, 32, 20133 Milan, Italy.
| | - B Horváth
- Biological Research Centre, Institute of Biophysics, Hungarian Academy of Sciences, Temesvári krt. 62, 6726 Szeged, Hungary
| | - P Ormos
- Biological Research Centre, Institute of Biophysics, Hungarian Academy of Sciences, Temesvári krt. 62, 6726 Szeged, Hungary
| | - R Osellame
- Institute for Photonics and Nanotechnologies, National Research Council, Piazza Leonardo da Vinci, 32, 20133 Milan, Italy.
| | - R Martínez Vázquez
- Institute for Photonics and Nanotechnologies, National Research Council, Piazza Leonardo da Vinci, 32, 20133 Milan, Italy.
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10
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Horváth B, Ormos P, Kelemen L. Nearly Aberration-Free Multiphoton Polymerization into Thick Photoresist Layers. Micromachines (Basel) 2017; 8:E219. [PMID: 30400410 PMCID: PMC6190196 DOI: 10.3390/mi8070219] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 06/21/2017] [Accepted: 07/06/2017] [Indexed: 11/16/2022]
Abstract
In the era of lab-on-chip (LOC) devices, two-photon polymerization (TPP) is gaining more and more interest due to its capability of producing micrometer-sized 3D structures. With TPP, one may integrate functional structures into microfluidic systems by polymerizing them directly inside microchannels. When the feature of sub-micrometer size is a requirement, it is necessary to use high numerical aperture (NA) oil-immersion objectives that are optimized to work close to the glass substrate-photoresist interface. Further away from the substrate, that is, a few tens of micrometers into the photoresist, the focused beam undergoes focal spot elongation and focal position shift. These effects may eventually reduce the quality of the polymerized structures; therefore, it is desirable to eliminate them. We introduce a method that can highly improve the quality of structures polymerized tens of micrometers away from the substrate-photoresist interface by an oil-immersion, high NA objective. A spatial light-modulator is used to pre-compensate the phase-front distortion introduced by the interfacial refractive index jump on the strongly converging beam.
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Affiliation(s)
- Bence Horváth
- Biological Research Centre, Institute of Biophysics, Hungarian Academy of Sciences, Temesvári krt. 62, 6726 Szeged, Hungary.
| | - Pál Ormos
- Biological Research Centre, Institute of Biophysics, Hungarian Academy of Sciences, Temesvári krt. 62, 6726 Szeged, Hungary.
| | - Lóránd Kelemen
- Biological Research Centre, Institute of Biophysics, Hungarian Academy of Sciences, Temesvári krt. 62, 6726 Szeged, Hungary.
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11
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Berchuck A, Tyrer J, Kelemen L, Phelan C, Pearce C, Moysich K, Lawrenson K, Schildkraut J, Sellers T, Goode E, Gayther S, Pharoah P. Genome-wide significant associations of common low penetrance single nucleotide polymorphisms with risk of mucinous ovarian carcinoma. Gynecol Oncol 2017. [DOI: 10.1016/j.ygyno.2017.03.107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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12
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Koos K, Molnár J, Kelemen L, Tamás G, Horvath P. DIC image reconstruction using an energy minimization framework to visualize optical path length distribution. Sci Rep 2016; 6:30420. [PMID: 27453091 PMCID: PMC4958949 DOI: 10.1038/srep30420] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 07/01/2016] [Indexed: 11/28/2022] Open
Abstract
Label-free microscopy techniques have numerous advantages such as low phototoxicity, simple setup and no need for fluorophores or other contrast materials. Despite their advantages, most label-free techniques cannot visualize specific cellular compartments or the location of proteins and the image formation limits quantitative evaluation. Differential interference contrast (DIC) is a qualitative microscopy technique that shows the optical path length differences within a specimen. We propose a variational framework for DIC image reconstruction. The proposed method largely outperforms state-of-the-art methods on synthetic, artificial and real tests and turns DIC microscopy into an automated high-content imaging tool. Image sets and the source code of the examined algorithms are made publicly available.
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Affiliation(s)
- Krisztian Koos
- Synthetic and Systems Biology Unit, Hungarian Academy of Sciences, BRC, Szeged, Hungary
| | - József Molnár
- Synthetic and Systems Biology Unit, Hungarian Academy of Sciences, BRC, Szeged, Hungary
| | - Lóránd Kelemen
- Institute of Biophysics, Hungarian Academy of Sciences, BRC, Szeged, Hungary
| | - Gábor Tamás
- MTA-SZTE Research Group for Cortical Microcircuits, Department of Physiology, Anatomy and Neuroscience, University of Szeged, Szeged, Hungary
| | - Peter Horvath
- Synthetic and Systems Biology Unit, Hungarian Academy of Sciences, BRC, Szeged, Hungary.,Institute for Molecular Medicine Finland (FIMM), University of Helsinki, Helsinki, Finland
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13
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Aekbote BL, Fekete T, Jacak J, Vizsnyiczai G, Ormos P, Kelemen L. Surface-modified complex SU-8 microstructures for indirect optical manipulation of single cells. Biomed Opt Express 2016; 7:45-56. [PMID: 26819816 PMCID: PMC4722909 DOI: 10.1364/boe.7.000045] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Revised: 11/19/2015] [Accepted: 11/20/2015] [Indexed: 05/24/2023]
Abstract
We introduce a method that combines two-photon polymerization (TPP) and surface functionalization to enable the indirect optical manipulation of live cells. TPP-made 3D microstructures were coated specifically with a multilayer of the protein streptavidin and non-specifically with IgG antibody using polyethylene glycol diamine as a linker molecule. Protein density on their surfaces was quantified for various coating methods. The streptavidin-coated structures were shown to attach to biotinated cells reproducibly. We performed basic indirect optical micromanipulation tasks with attached structure-cell couples using complex structures and a multi-focus optical trap. The use of such extended manipulators for indirect optical trapping ensures to keep a safe distance between the trapping beams and the sensitive cell and enables their 6 degrees of freedom actuation.
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Affiliation(s)
- Badri L. Aekbote
- Biological Research Centre of the Hungarian Academy of Sciences, Temesvári krt. 62, Szeged 6726, Hungary
| | - Tamás Fekete
- Biological Research Centre of the Hungarian Academy of Sciences, Temesvári krt. 62, Szeged 6726, Hungary
| | - Jaroslaw Jacak
- University of Applied Sciences Upper Austria, Garnisonstraße 21, 4020 Linz, Austria
| | - Gaszton Vizsnyiczai
- Biological Research Centre of the Hungarian Academy of Sciences, Temesvári krt. 62, Szeged 6726, Hungary
| | - Pál Ormos
- Biological Research Centre of the Hungarian Academy of Sciences, Temesvári krt. 62, Szeged 6726, Hungary
| | - Lóránd Kelemen
- Biological Research Centre of the Hungarian Academy of Sciences, Temesvári krt. 62, Szeged 6726, Hungary
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14
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Vizsnyiczai G, Lestyán T, Joniova J, Aekbote BL, Strejčková A, Ormos P, Miskovsky P, Kelemen L, Bánó G. Optically Trapped Surface-Enhanced Raman Probes Prepared by Silver Photoreduction to 3D Microstructures. Langmuir 2015; 31:10087-93. [PMID: 26292094 DOI: 10.1021/acs.langmuir.5b01210] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
3D microstructures partially covered by silver nanoparticles have been developed and tested for surface-enhanced Raman spectroscopy (SERS) in combination with optical tweezers. The microstructures made by two-photon polymerization of SU-8 photoresist were manipulated in a dual beam optical trap. The active area of the structures was covered by a SERS-active silver layer using chemically assisted photoreduction from silver nitrate solutions. Silver layers of different grain size distributions were created by changing the photoreduction parameters and characterized by scanning electron microscopy. The structures were tested by measuring the SERS spectra of emodin and hypericin.
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Affiliation(s)
- Gaszton Vizsnyiczai
- Biological Research Centre, Institute of Biophysics, Hungarian Academy of Sciences , Temesvári krt. 62, Szeged, Hungary
| | - Tamás Lestyán
- Biological Research Centre, Institute of Biophysics, Hungarian Academy of Sciences , Temesvári krt. 62, Szeged, Hungary
| | | | - Badri L Aekbote
- Biological Research Centre, Institute of Biophysics, Hungarian Academy of Sciences , Temesvári krt. 62, Szeged, Hungary
| | - Alena Strejčková
- Department of Chemistry, Biochemistry and Biophysics, Institute of Biophysics, University of Veterinary Medicine and Pharmacy , Komenského 73, 04181 Košice, Slovakia
| | - Pál Ormos
- Biological Research Centre, Institute of Biophysics, Hungarian Academy of Sciences , Temesvári krt. 62, Szeged, Hungary
| | | | - Lóránd Kelemen
- Biological Research Centre, Institute of Biophysics, Hungarian Academy of Sciences , Temesvári krt. 62, Szeged, Hungary
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15
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Vizsnyiczai G, Kelemen L, Ormos P. Holographic multi-focus 3D two-photon polymerization with real-time calculated holograms. Opt Express 2014; 22:24217-23. [PMID: 25321996 DOI: 10.1364/oe.22.024217] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Two-photon polymerization enables the fabrication of micron sized structures with submicron resolution. Spatial light modulators (SLM) have already been used to create multiple polymerizing foci in the photoresist by holographic beam shaping, thus enabling the parallel fabrication of multiple microstructures. Here we demonstrate the parallel two-photon polymerization of single 3D microstructures by multiple holographically translated foci. Multiple foci were created by phase holograms, which were calculated real-time on an NVIDIA CUDA GPU, and displayed on an electronically addressed SLM. A 3D demonstrational structure was designed that is built up from a nested set of dodecahedron frames of decreasing size. Each individual microstructure was fabricated with the parallel and coordinated motion of 5 holographic foci. The reproducibility and the high uniformity of features of the microstructures were verified by scanning electron microscopy.
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16
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Palima D, Bañas AR, Vizsnyiczai G, Kelemen L, Aabo T, Ormos P, Glückstad J. Optical forces through guided light deflections. Opt Express 2013; 21:581-593. [PMID: 23388951 DOI: 10.1364/oe.21.000581] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Optical trapping and manipulation typically relies on shaping focused light to control the optical force, usually on spherical objects. However, one can also shape the object to control the light deflection arising from the light-matter interaction and, hence, achieve desired optomechanical effects. In this work we look into the object shaping aspect and its potential for controlled optical manipulation. Using a simple bent waveguide as example, our numerical simulations show that the guided deflection of light efficiently converts incident light momentum into optical force with one order-of-magnitude improvement in the efficiency factor relative to a microbead, which is comparable to the improvement expected from orthogonal deflection with a perfect mirror. This improvement is illustrated in proof-of-principle experiments demonstrating the optical manipulation of two-photon polymerized waveguides. Results show that the force on the waveguide exceeds the combined forces on spherical trapping handles. Furthermore, it shows that static illumination can exert a constant force on a moving structure, unlike the position-dependent forces from harmonic potentials in conventional trapping.
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Affiliation(s)
- Darwin Palima
- DTU Fotonik, Department of Photonics Engineering, Technical University of Denmark, Kgs. Lyngby, Denmark.
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17
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Aekbote BL, Jacak J, Schütz GJ, Csányi E, Szegletes Z, Ormos P, Kelemen L. Aminosilane-based functionalization of two-photon polymerized 3D SU-8 microstructures. Eur Polym J 2012. [DOI: 10.1016/j.eurpolymj.2012.06.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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18
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Di Leonardo R, Búzás A, Kelemen L, Vizsnyiczai G, Oroszi L, Ormos P. Hydrodynamic synchronization of light driven microrotors. Phys Rev Lett 2012; 109:034104. [PMID: 22861857 DOI: 10.1103/physrevlett.109.034104] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Revised: 05/29/2012] [Indexed: 05/28/2023]
Abstract
Hydrodynamic synchronization is a fundamental physical phenomenon by which self-sustained oscillators communicate through perturbations in the surrounding fluid and converge to a stable synchronized state. This is an important factor for the emergence of regular and coordinated patterns in the motions of cilia and flagella. When dealing with biological systems, however, it is always hard to disentangle internal signaling mechanisms from external purely physical couplings. We have used the combination of two-photon polymerization and holographic optical trapping to build a mesoscale model composed of chiral propellers rotated by radiation pressure. The two microrotors can be synchronized by hydrodynamic interactions alone although the relative torques have to be finely tuned. Dealing with a micron sized system we treat synchronization as a stochastic phenomenon and show that the phase lag between the two microrotors is distributed according to a stationary Fokker-Planck equation for an overdamped particle over a tilted periodic potential. Synchronized states correspond to minima in this potential whose locations are shown to depend critically on the detailed geometry of the propellers.
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Affiliation(s)
- R Di Leonardo
- IPCF-CNR UOS Roma, Dipartimento di Fisica, Università Sapienza, I-00185 Rome, Italy.
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19
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Abstract
This work primarily aims to fabricate and use two photon polymerization (2PP) microstructures capable of being optically manipulated into any arbitrary orientation. We have integrated optical waveguides into the structures and therefore have freestanding waveguides, which can be positioned anywhere in the sample at any orientation using optical traps. One of the key aspects to the work is the change in direction of the incident plane wave, and the marked increase in the numerical aperture demonstrated. Hence, the optically steered waveguide can tap from a relatively broader beam and then generate a more tightly confined light at its tip. The paper contains both simulation, related to the propagation of light through the waveguide, and experimental demonstrations using our BioPhotonics Workstation. In a broader context, this work shows that optically trapped microfabricated structures can potentially help bridge the diffraction barrier. This structure-mediated paradigm may be carried forward to open new possibilities for exploiting beams from far-field optics down to the subwavelength domain.
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Affiliation(s)
- D Palima
- DTU Fotonik, Dept. of Photonics Engineering, Technical University of Denmark, DK-2800, Kgs. Lyngby, Denmark
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20
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Rodrigo PJ, Kelemen L, Palima D, Alonzo CA, Ormos P, Glückstad J. Optical microassembly platform for constructing reconfigurable microenvironments for biomedical studies. Opt Express 2009; 17:6578-6583. [PMID: 19365483 DOI: 10.1364/oe.17.006578] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Cellular development is highly influenced by the surrounding microenvironment. We propose user-reconfigurable microenvironments and bio-compatible scaffolds as an approach for understanding cellular development processes. We demonstrate a model platform for constructing versatile microenvironments by fabricating morphologically complex microstructures by two-photon polymerization (2PP) and then assembling these archetypal building blocks into various configurations using multiple, real-time configurable counterpropagating-beam (CB) traps. The demonstrated capacity for handling feature-rich microcomponents may be further developed into a generalized microassembly platform.
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21
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Jeske YWA, So A, Kelemen L, Sukor N, Willys C, Bulmer B, Gordon RD, Duffy D, Stowasser M. EXAMINATION OF CHROMOSOME 7p22 CANDIDATE GENES RBaK, PMS2 AND GNA12 IN FAMILIAL HYPERALDOSTERONISM TYPE II. Clin Exp Pharmacol Physiol 2008; 35:380-5. [DOI: 10.1111/j.1440-1681.2008.04882.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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22
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Kelemen L, Valkai S, Ormos P. Parallel photopolymerisation with complex light patterns generated by diffractive optical elements. Opt Express 2007; 15:14488-97. [PMID: 19550727 DOI: 10.1364/oe.15.014488] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Photopolymerisation by scanning a focused laser beam is a powerful method to build structures of arbitrary complexity with submicrometer resolution. We introduce parallel photopolymerisation to enhance the efficiency. Instead of multidimensional scanning of a single focus, the structure is generated simultaneously with diffractive patterns. We used fixed diffractive optical elements (DOEs), kinoforms, and Spatial Light Modulators (SLMs). The possibilities of photopolymerisation using SLM were investigated: the added flexibility using the programmable device is demonstrated. By using these DOEs, straight and helical cross shaped columns were produced with a single scan at a rate about an order of magnitude faster than by simple scanning. The produced helical structures could be rotated by optical tweezers.
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23
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Rodrigo PJ, Kelemen L, Alonzo CA, Perch-Nielsen IR, Dam JS, Ormos P, Glückstad J. 2D optical manipulation and assembly of shape-complementary planar microstructures. Opt Express 2007; 15:9009-9014. [PMID: 19547240 DOI: 10.1364/oe.15.009009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Optical trapping and manipulation offer great flexibility as a non-contact microassembly tool. Its application to the assembly of microscale building blocks may open new doors for micromachine technology. In this work, we demonstrate all-optical assembly of microscopic puzzle pieces in a fluidic environment using programmable arrays of trapping beams. Identical shape-complimentary pieces are optically fabricated with submicron resolution using two-photon polymerization (2PP) technique. These are efficiently assembled into space-filling tessellations by a multiple-beam optical micromanipulation system. The flexibility of the system allows us to demonstrate both user-interactive and computer-automated modes of serial and parallel assembly of microscale objects with high spatial and angular positioning precision.
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Dér A, Kelemen L, Fábián L, Taneva SG, Fodor E, Páli T, Cupane A, Cacace MG, Ramsden JJ. Interfacial Water Structure Controls Protein Conformation. J Phys Chem B 2007; 111:5344-50. [PMID: 17458989 DOI: 10.1021/jp066206p] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A phenomenological theory of salt-induced Hofmeister phenomena is presented, based on a relation between protein solubility in salt solutions and protein-water interfacial tension. As a generalization of previous treatments, it implies that both kosmotropic salting out and chaotropic salting in are manifested via salt-induced changes of the hydrophobic/hydrophilic properties of protein-water interfaces. The theory is applied to describe the salt-dependent free energy profiles of proteins as a function of their water-exposed surface area. On this basis, three classes of protein conformations have been distinguished, and their existence experimentally demonstrated using the examples of bacteriorhodopsin and myoglobin. The experimental results support the ability of the new formalism to account for the diverse manifestations of salt effects on protein conformation, dynamics, and stability, and to resolve the puzzle of chaotropes stabilizing certain proteins (and other anomalies). It is also shown that the relation between interfacial tension and protein structural stability is straightforwardly linked to protein conformational fluctuations, providing a keystone for the microscopic interpretation of Hofmeister effects. Implications of the results concerning the use of Hofmeister effects in the experimental study of protein function are discussed.
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Affiliation(s)
- A Dér
- Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences (MTA-SzBK), Pf. 521, H-6701 Szeged, Hungary.
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25
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Abstract
A light-driven micrometer-sized mechanical motor is created by laser-light-induced two-photon photopolymerization. All necessary components of the engine are built upon a glass surface by an identical procedure and include the following: a rigid mechanical framework, a rotor freely rotating on an axis, and an integrated optical waveguide carrying the actuating light to the rotor. The resulting product is a most practical stand-alone system. The light introduced into the integrated optical waveguide input of the motor provides the driving force: neither optical tweezers or even a microscope are needed for the function. The power and efficiency of the motor are evaluated. The independent unit is expected to become an important component of more complex integrated lab-on-a-chip devices.
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Affiliation(s)
- Lóránd Kelemen
- Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Szeged
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26
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Kelemen L, Rizk S, Debreczeny M, Ogier J, Szalontai B. Streptococcal antigen I/II binds to extracellular proteins through intermolecular beta-sheets. FEBS Lett 2004; 566:190-4. [PMID: 15147893 DOI: 10.1016/j.febslet.2004.04.029] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2004] [Revised: 03/30/2004] [Accepted: 04/03/2004] [Indexed: 11/25/2022]
Abstract
One of the functions associated with the oral streptococcal surface protein I/II is to bind to human extracellular matrix molecules or blood components, which could act as opportunistic ligands in pathological circumstances. In order to understand the relative specificity of the binding repertoire of this bacterial adhesin, we examined by infrared measurements the mode of binding of the protein I/II from Streptococcus mutans OMZ175 (I/IIf) to fibronectin and fibrinogen. This approach revealed the beta-structure forming capacity of I/IIf upon interaction with both proteins. The forming of intermolecular beta-structures may provide a non-selective way of interaction between I/IIf and its possible targets.
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Affiliation(s)
- Lóránd Kelemen
- Institute of Biophysics, Biological Research Centre of the Hungarian Academy of Sciences, Temesvári krt 62, P.O.B. 521, H-6701 Szeged, Hungary
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Abstract
A simple HPLC method with fluorescence detection of ciprofloxacin in human plasma was developed and validated. After protein precipitation, chromatographic separation of ciprofloxacin in plasma was achieved at 35 degrees C with a C18 column and acetonitrile-phosphate mixture, pH 3, as mobile phase. Quantitative determination was performed by fluorimetry after excitation at 278 nm. The method was specific and validated with a limit of quantification of 41 ng/ml. The intra- and inter-day coefficients of variation were between 0.5 and 6.6% and accuracy between -2.02 and 7.04%. Ciprofloxacin was stable in plasma for 40 days at -20 degrees C and after three freezing-thawing cycles. The method has been applied in a bioequivalence study of two formulation of 500 mg ciprofloxacin.
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Affiliation(s)
- Silvia Imre
- Faculty of Pharmacy, University of Medicine and Pharmacy, Gh. Marinescu Street, 38, Tg. Mures 4300, Romania.
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28
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Kelemen L, Ormos P. Structural changes in bacteriorhodopsin during the photocycle measured by time-resolved polarized Fourier transform infrared spectroscopy. Biophys J 2001; 81:3577-89. [PMID: 11721018 PMCID: PMC1301812 DOI: 10.1016/s0006-3495(01)75988-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The structural changes in bacteriorhodopsin during the photocycle are investigated. Time resolved polarized infrared spectroscopy in combination with photoselection is used to determine the orientation and motion of certain structural units of the molecule: Asp-85, Asp-96, Asp-115, the Schiff base, and several amide I vibrations. The results are compared with recently published x-ray diffraction data with atomic resolution about conformational motions during the photocycle. The orientation of the measured vibrations are also calculated from the structure data, and based on the comparison of the values from the two techniques new information is obtained: several amide I bands in the infrared spectrum are assigned, and we can also identify the position of the proton in the protonated Asp residues.
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Affiliation(s)
- L Kelemen
- Institute of Biophysics, Biological Research Centre of the Hungarian Academy of Sciences, Szeged H-6701, Hungary
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Abstract
The photocycle of dried bacteriorhodopsin, pretreated in a 0.3 M HCl solution, was studied. Some properties of this dried sample resemble that of the acid purple suspension: the retinal conformation is mostly all-trans, 15-anti form, the spectrum of the sample is blue-shifted by 5 nm to 560 nm, and it has a truncated photocycle. After photoexcitation, a K-like red-shifted intermediate appears, which decays to the ground state through several intermediates with spectra between the K and the ground state. There are no other bacteriorhodopsin-like intermediates (L, M, N, O) present in the photocycle. The K to K' transition proceeds with an enthalpy decrease, whereas during all the following steps, the entropic energy of the system decreases. The electric response signal of the oriented sample has only negative components, which relaxes to zero. These suggest that the steps after intermediate K represent a relaxation process, during which the absorbed energy is dissipated and the protein returns to its original ground state. The initial charge separation on the retinal is followed by limited charge rearrangements in the protein, and later, all these relax. The decay times of the intermediates are strongly influenced by the humidity of the sample. Double-flash experiments proved that all the intermediates are directly driven back to the ground state. The study of the dried acid purple samples could help in understanding the fast primary processes of the protein function. It may also have importance in technical applications.
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Affiliation(s)
- G I Groma
- Institute of Biophysics, Biological Research Center of the Hungarian Academy of Sciences, Szeged H-6701, Hungary
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Xie A, Kelemen L, Hendriks J, White BJ, Hellingwerf KJ, Hoff WD. Formation of a new buried charge drives a large-amplitude protein quake in photoreceptor activation. Biochemistry 2001; 40:1510-7. [PMID: 11327809 DOI: 10.1021/bi002449a] [Citation(s) in RCA: 181] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Photoactive yellow protein (PYP) is a eubacterial photoreceptor and a structural prototype of the PAS domain superfamily of receptor and regulatory proteins. We investigate the activation mechanism of PYP using time-resolved Fourier transform infrared (FTIR) spectroscopy. Our data provide structural, kinetic, and energetic evidence that the putative signaling state of PYP is formed during a large-amplitude protein quake that is driven by the formation of a new buried charge, COO(-) of the conserved Glu46, in a highly hydrophobic pocket at the active site. A protein quake is a process consisting of global conformational changes that are triggered and driven by a local structural "fault". We show that large, global structural changes take place after Glu46 ionization via intramolecular proton transfer to the anionic p-coumarate chromophore, and are suppressed by the absence of COO(-) formation in the E46Q mutant. Our results demonstrate the significance of buried charge formation in photoreceptor activation. This mechanism may serve as one of the general themes in activation of a range of receptor proteins. In addition, we report the results of time-resolved FTIR spectroscopy of PYP crystals. The direct comparison of time-resolved FTIR spectroscopic data of PYP in aqueous solution and in crystals reveals that the structure of the putative signaling state is not developed in P6(3) crystals. Therefore, when the structural developments during the functional process of a protein are experimentally determined to be very different in crystals and solutions, one must be cautious in drawing conclusions regarding the functional mechanism of proteins based on time-resolved X-ray crystallography.
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Affiliation(s)
- A Xie
- Department of Physics, Oklahoma State University, 145 Physical Sciences II, Stillwater, OK 74078, USA.
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31
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Anand SS, Yusuf S, Vuksan V, Devanesen S, Teo KK, Montague PA, Kelemen L, Yi C, Lonn E, Gerstein H, Hegele RA. Differences in risk factors, atherosclerosis and cardiovascular disease between ethnic groups in Canada: the study of health assessment and risk in ethnic groups (SHARE). Indian Heart J 2000; 52:S35-43. [PMID: 11339439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023] Open
Abstract
Cardiovascular disease rates vary greatly between ethnic groups in Canada. To establish whether this variation can be explained by differences in disease risk factors and subclinical atherosclerosis, we undertook a population-based study of three ethnic groups in Canada: South Asians, Chinese and Europeans. A total of 985 participants were recruited from three cities (Hamilton, Toronto and Edmonton) by stratified random sampling. Clinical cardiovascular disease was defined by history or electrocardiographic findings. Carotid atherosclerosis was measured with B-mode ultrasonography. Conventional (smoking, hypertension, diabetes, raised cholesterol) and novel risk factors (markers of a prothrombotic state) were measured. Within each ethnic group and overall, the degree of carotid atherosclerosis was associated with a higher prevalence of cardiovascular disease. South Asians had the highest prevalence of this condition compared with Europeans and Chinese (11%, 5% and 2%, respectively; p=0.0004). Despite this finding, Europeans had more atherosclerosis (mean of the maximum intimal medial thickness 0.75 [0.16] mm) than South Asians (0.72 [0.15] mm) and Chinese (0.69 [0.16] mm). South Asians had an increased prevalence of glucose intolerance, higher total and low-density lipoprotein cholesterol, higher triglycerides and lower high-density lipoprotein cholesterol, and much greater abnormalities in novel risk factors including higher concentrations of fibrinogen, homocysteine, lipoprotein(a), and plasminogen activator inhibitor-1. Although there are differences in conventional and novel risk factors between ethnic groups, this variation and the degree of atherosclerosis only partly explains the higher rates of cardiovascular disease among South Asians compared with Europeans and Chinese. The increased risk of cardiovascular events could be due to factors affecting plaque rupture, the interaction between prothrombotic factors and atherosclerosis, or as yet undiscovered risk factors.
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Affiliation(s)
- S S Anand
- Departments of Medicine, Pathology and Molecular Medicine, McMaster University, Ontario, Canada
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32
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Anand SS, Yusuf S, Vuksan V, Devanesen S, Teo KK, Montague PA, Kelemen L, Yi C, Lonn E, Gerstein H, Hegele RA, McQueen M. Differences in risk factors, atherosclerosis, and cardiovascular disease between ethnic groups in Canada: the Study of Health Assessment and Risk in Ethnic groups (SHARE). Lancet 2000; 356:279-84. [PMID: 11071182 DOI: 10.1016/s0140-6736(00)02502-2] [Citation(s) in RCA: 688] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
BACKGROUND Cardiovascular disease rates vary greatly between ethnic groups in Canada. To establish whether this variation can be explained by differences in disease risk factors and subclinical atherosclerosis, we undertook a population-based study of three ethnic groups in Canada: South Asians, Chinese, and Europeans. METHODS 985 participants were recruited from three cities (Hamilton, Toronto, and Edmonton) by stratified random sampling. Clinical cardiovascular disease was defined by history or electrocardiographic findings. Carotid atherosclerosis was measured with B-mode ultrasonography. Conventional (smoking, hypertension, diabetes, raised cholesterol) and novel risk factors (markers of a prothrombotic state) were measured. FINDINGS Within each ethnic group and overall, the degree of carotid atherosclerosis was associated with a higher prevalence of cardiovascular disease. South Asians had the highest prevalence of this condition compared with Europeans and Chinese (11%, 5%, and 2%, respectively, p=0.0004). Despite this finding, Europeans had more atherosclerosis (mean of the maximum intimal medial thickness 0.75 [0.16] mm) than South Asians (0.72 [0.15] mm), and Chinese (0.69 [0.16] mm). South Asians had an increased prevalence of glucose intolerance, higher total and LDL cholesterol, higher triglycerides, and lower HDL cholesterol, and much greater abnormalities in novel risk factors including higher concentrations of fibrinogen, homocysteine, lipoprotein (a), and plasminogen activator inhibitor-1. INTERPRETATION Although there are differences in conventional and novel risk factors between ethnic groups, this variation and the degree of atherosclerosis only partly explains the higher rates of cardiovascular disease among South Asians compared with Europeans and Chinese. The increased risk of cardiovascular events could be due to factors affecting plaque rupture, the interaction between prothrombotic factors and atherosclerosis, or as yet undiscovered risk factors.
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Affiliation(s)
- S S Anand
- Department of Medicine, McMaster University, Ontario, Canada.
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33
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Tókés B, Ferencz L, Szakács J, Kelemen L, Darkó B. Retrometabolic approaches in phytobiochemistry. Pharmazie 2000; 55:244-5. [PMID: 10756551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Affiliation(s)
- B Tókés
- University of Medicine and Pharmacy, Tg.Mureş (Marosvásárhely), Romania.
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Abstract
Bacteriorhodopsin (bR) and halorhodopsin (hR) are light-induced ion pumps in the cell membrane of Halobacterium salinarium. Under normal conditions bR is an outward proton transporter, whereas hR is an inward Cl- transporter. There is strong evidence that at very low pH and in the presence of Cl-, bR transports Cl- ions into the cell, similarly to hR. The chloride pumping activity of bR is connected to the so-called acid purple state. To account for the observed effects in bR a tentative complex counterion was suggested for the protonated Schiff base of the retinal chromophore. It would consist of three charged residues: Asp-85, Asp-212, and Arg-82. This quadruplet (including the Schiff base) would also serve as a Cl- binding site at low pH. We used Fourier transform infrared difference spectroscopy to study the structural changes during the transitions between the normal, acid blue, and acid purple states. Asp-85 and Asp-212 were shown to participate in the transitions. During the normal-to-acid blue transition, Asp-85 protonates. When the pH is further lowered in the presence of Cl-, Cl- binds and Asp-212 also protonates. The binding of Cl- and the protonation of Asp-212 occur simultaneously, but take place only when Asp-85 is already protonated. It is suggested that HCl is taken up in undissociated form in exchange for a neutral water molecule.
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Affiliation(s)
- L Kelemen
- Institute of Biophysics, Biological Research Center of the Hungarian Academy of Sciences, Szeged, H-6701 Hungary
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35
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Anand SS, Yusuf S, Vuksan V, Devanesen S, Montague P, Kelemen L, Bosch J, Sigouin C, Teo KK, Lonn E, Gerstein HC, Hegele RA, McQueen M. The Study of Health Assessment and Risk in Ethnic groups (SHARE): rationale and design. The SHARE Investigators. Can J Cardiol 1998; 14:1349-57. [PMID: 9854515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023] Open
Abstract
The Study of Health Assessment and Risk in Ethnic groups (SHARE) is a study to determine the risk factors for atherosclerosis among three ethnic populations in Canada. Three hundred and thirty South Asian Canadian, 320 Chinese Canadian and 320 European Canadian men and women between 35 and 75 years of age are being randomly sampled from communities in Hamilton and Toronto, Ontario and Edmonton, Alberta for assessment of conventional (i.e., smoking, dyslipidemia, diabetes and hypertension) and emerging (i.e., candidate genes for atherosclerosis, homocysteine, fibrinolytic parameters, neurohormones, glucose intolerance, markers of infection, socioeconomic status, psychosocial status and diet) cardiovascular disease risk factors. Subclinical atherosclerosis is measured by quantitative B-mode ultrasonography of the carotid arteries, and other objective measures of vascular disease are a 12-lead electrocardiogram, a two-dimensional echocardiogram, ankle to arm blood pressure ratio and urine microalbumin concentration. The relationship between the conventional and emerging risk factors, and atherosclerosis, vascular disease and markers of end-organ damage will be evaluated between and within ethnic groups.
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Affiliation(s)
- S S Anand
- Preventive Cardiology and Therapeutics Research Program, Hamilton Civic Hospitals Research Centre, McMaster University, Ontario.
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36
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Kelemen L, Anand S. Moderately reduced dietary fat intake was associated with reduced LDL cholesterol in hypercholesterolemic and combined hyperlipidemic men. Evid Based Cardiovasc Med 1998; 2:58-60. [PMID: 16379818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Affiliation(s)
- L Kelemen
- McMaster University, Hamilton, Ontario, Canada
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37
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Kelemen L, Anand S. Sexual maturation, BMI, dietary intervention and dietary cholesterol reduced LDL cholesterol in children. Evid Based Cardiovasc Med 1998; 2:58-60. [PMID: 16379817 DOI: 10.1016/s1361-2611(98)80099-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Affiliation(s)
- L Kelemen
- McMaster University, Hamilton, Ontario, Canada
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38
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Ondeyka JG, Goegelman RT, Schaeffer JM, Kelemen L, Zitano L. Novel antinematodal and antiparasitic agents from Penicillium charlesii. I. Fermentation, isolation and biological activity. J Antibiot (Tokyo) 1990; 43:1375-9. [PMID: 2272914 DOI: 10.7164/antibiotics.43.1375] [Citation(s) in RCA: 96] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Paraherquamide and six novel analogs were isolated from the fermentation of Penicillium charlesii (ATCC 20841). All seven natural products displayed potent antinematodal activity against Caenorhabditis elegans. None of the novel analogs were more potent than paraherquamide.
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Affiliation(s)
- J G Ondeyka
- Merck & Co., Inc., Rahway, New Jersey 07065-0900
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39
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Szendrői Z, Kelemen L, Solymossy E, Tóth K. Book reviews. Int Urol Nephrol 1989. [DOI: 10.1007/bf02549596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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40
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Vitos A, Hecser L, Szabó M, Kelemen L, Tiriac E. [Renal adenoma]. Rev Chir Oncol Radiol O R L Oftalmol Stomatol Chir 1980; 29:207-10. [PMID: 6450971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The authors present a case of renal adenoma, a benign renal tumour rarely encountered in the clinic, especially of this size (9/10 cm), and diagnosed intravitam as an obstructive urinary syndrome, with destruction of the renal parenchyma and suppression of the renal function. The patient's condition was good after nephrectomy.
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41
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Kelemen L, Keresztély J, Csösz IK, Gross KD, Nistor ME, Cojocaru I, Konrád G. [Various data on the epidemiology and clinical aspects of acute enterocolitis of staphylococcal origin]. Med Interna (Bucur) 1974; 26:717-22. [PMID: 4153253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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42
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Szentkirályi E, Kasza L, Konrád G, Gáspar J, Ionescu R, Nagy A, Vincze L, Kelemen L. [Diagnostic and therapeutic problems in some cases of meningitis with multi-resistant gram negative bacilli]. Neurol Psihiatr Neurochir 1973; 18:443-52. [PMID: 4790479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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43
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Szentkirályi E, Koválszki P, Szabó J, Tuka P, Jaklovszki A, Kelemen L. [On an epidemic of infectious mononucleosis. Diagnostic problems]. Pediatria (Bucur) 1973; 22:129-38. [PMID: 4720585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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44
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Kelemen L, Szentkirályi E, Konrád G, Pascu R, Nagy A, Márer ES, Runcan C, Cojocaru I. [Some current clinical and therapeutic aspects of septicemias]. Med Interna (Bucur) 1972; 24:347-56. [PMID: 5026914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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45
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Konrád G, Kelemen L, Kerestély J, Domokos L, Moldovan V. [On bacillary dysentery between the years 1965 and 1970]. Microbiol Parazitol Epidemiol (Bucur) 1972; 17:111-20. [PMID: 4553092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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46
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Szentkirályi E, Gáspár I, Szabó L, Szabó J, Ionescu R, Kelemen L. [Observations on several cases of recurrent meningoencephalitis with prolonged evolution due to relapses]. Neurol Psihiatr Neurochir 1971; 16:343-54. [PMID: 5118393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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47
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Kelemen L, Gyergyay R, Pascu RI, László J, Kelemen A. [Clinical and histopathological studies of the liver in epidemic parotitis]. Med Interna (Bucur) 1971; 23:659-65. [PMID: 5565657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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48
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Kovács F, Szentkirályi E, Konrád G, Fazakas B, Kelemen L. [Clinical and epidemiological observations on a focus of trichinelliasis of a familial type]. Microbiol Parazitol Epidemiol (Bucur) 1970; 15:415-21. [PMID: 4395495] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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49
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Kovács F, Szentkirályi E, Gáspár S, Szabó L, Kelemen L. [On the influence of current treatment on the mortality and sequelae of meningoencephalitis]. Neurol Psihiatr Neurochir 1970; 15:355-68. [PMID: 5486669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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50
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Szentkirályi E, Gáspár I, Kovács F, Kelemen L. [On hydrocephalus following menintoencephalitis treated with corticoids]. Neurol Psihiatr Neurochir 1970; 15:213-26. [PMID: 5456226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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