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Setoura K, Ito S. Optical manipulation in conjunction with photochemical/photothermal responses of materials. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY C: PHOTOCHEMISTRY REVIEWS 2022. [DOI: 10.1016/j.jphotochemrev.2022.100536] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/08/2023]
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Bléger D, Liebig T, Thiermann R, Maskos M, Rabe JP, Hecht S. Light-Orchestrated Macromolecular “Accordions”: Reversible Photoinduced Shrinking of Rigid-Rod Polymers. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201106879] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Bléger D, Liebig T, Thiermann R, Maskos M, Rabe JP, Hecht S. Light-Orchestrated Macromolecular “Accordions”: Reversible Photoinduced Shrinking of Rigid-Rod Polymers. Angew Chem Int Ed Engl 2011; 50:12559-63. [DOI: 10.1002/anie.201106879] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Indexed: 11/07/2022]
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Ito S, Tanaka Y, Yoshikawa H, Ishibashi Y, Miyasaka H, Masuhara H. Confinement of photopolymerization and solidification with radiation pressure. J Am Chem Soc 2011; 133:14472-5. [PMID: 21859111 DOI: 10.1021/ja200737j] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Controlling chemical reactions within a small space is a significant issue in chemistry, and methods to induce reactions within a desired position have various potential applications. Here we demonstrate localized, efficient photopolymerization by radiation pressure. We induced a one-photon UV polymerization of liquid acrylate solutions in the optical-trapping potential of a focused near-IR (NIR) laser beam, leading to the confinement of solidification to a minute space with dimensions smaller or equal to one-fifth of the wavelength of the NIR laser. Our approach can produce solidification volumes smaller than those achievable with conventional one-photon polymerization, thus enabling the production of tiny polymeric structures that are smaller than the diffraction limit of the trapping light. This is the first demonstration of a radiation pressure effect on a photochemical reaction.
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Affiliation(s)
- Syoji Ito
- Division of Frontier Materials Science, Graduate School of Engineering Science, and Center for Quantum Materials Science under Extreme Conditions, Osaka University, 1-3 Macikaneyama-cho, Toyonaka, Osaka 560-8531, Japan.
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Crivillers N, Orgiu E, Reinders F, Mayor M, Samorì P. Optical modulation of the charge injection in an organic field-effect transistor based on photochromic self-assembled-monolayer-functionalized electrodes. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2011; 23:1447-52. [PMID: 21433111 DOI: 10.1002/adma.201003736] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2010] [Revised: 11/18/2010] [Indexed: 05/03/2023]
Affiliation(s)
- Núria Crivillers
- Nanochemistry Laboratory, ISIS - CNRS, Université de Strasbourg, France
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Crivillers N, Liscio A, Di Stasio F, Van Dyck C, Osella S, Cornil D, Mian S, Lazzerini GM, Fenwick O, Orgiu E, Reinders F, Braun S, Fahlman M, Mayor M, Cornil J, Palermo V, Cacialli F, Samorì P. Photoinduced work function changes by isomerization of a densely packed azobenzene-based SAM on Au: a joint experimental and theoretical study. Phys Chem Chem Phys 2011; 13:14302-10. [DOI: 10.1039/c1cp20851a] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Raimondo C, Reinders F, Soydaner U, Mayor M, Samorì P. Light-responsive reversible solvation and precipitation of gold nanoparticles. Chem Commun (Camb) 2010; 46:1147-9. [DOI: 10.1039/b915491d] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Kamilya T, Pal P, Mahato M, Talapatra G. Immobilization and the conformational study of phospholipid and phospholipid-protein vesicles. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2009. [DOI: 10.1016/j.msec.2008.12.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Jung J, Lee IH, Lee E, Park J, Jon S. pH-Sensitive Polymer Nanospheres for Use as a Potential Drug Delivery Vehicle. Biomacromolecules 2007; 8:3401-7. [DOI: 10.1021/bm700517z] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Roeffaers MBJ, De Cremer G, Uji-i H, Muls B, Sels BF, Jacobs PA, De Schryver FC, De Vos DE, Hofkens J. Single-molecule fluorescence spectroscopy in (bio)catalysis. Proc Natl Acad Sci U S A 2007; 104:12603-9. [PMID: 17664433 PMCID: PMC1937513 DOI: 10.1073/pnas.0610755104] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The ever-improving time and space resolution and molecular detection sensitivity of fluorescence microscopy offer unique opportunities to deepen our insights into the function of chemical and biological catalysts. Because single-molecule microscopy allows for counting the turnover events one by one, one can map the distribution of the catalytic activities of different sites in solid heterogeneous catalysts, or one can study time-dependent activity fluctuations of individual sites in enzymes or chemical catalysts. By experimentally monitoring individuals rather than populations, the origin of complex behavior, e.g., in kinetics or in deactivation processes, can be successfully elucidated. Recent progress of temporal and spatial resolution in single-molecule fluorescence microscopy is discussed in light of its impact on catalytic assays. Key concepts are illustrated regarding the use of fluorescent reporters in catalytic reactions. Future challenges comprising the integration of other techniques, such as diffraction, scanning probe, or vibrational methods in single-molecule fluorescence spectroscopy are suggested.
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Affiliation(s)
- Maarten B. J. Roeffaers
- *Department of Microbial and Molecular Systems, Centre for Surface Chemistry and Catalysis, Katholieke Universiteit Leuven, Kasteelpark Arenberg 23, B-3001 Leuven, Belgium
| | - Gert De Cremer
- *Department of Microbial and Molecular Systems, Centre for Surface Chemistry and Catalysis, Katholieke Universiteit Leuven, Kasteelpark Arenberg 23, B-3001 Leuven, Belgium
| | - Hiroshi Uji-i
- Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium; and
| | - Benîot Muls
- Department of Chemistry, Université Catholique de Louvain, Place L. Pasteur 1, B-1348 Louvain-la-Neuve, Belgium
| | - Bert F. Sels
- *Department of Microbial and Molecular Systems, Centre for Surface Chemistry and Catalysis, Katholieke Universiteit Leuven, Kasteelpark Arenberg 23, B-3001 Leuven, Belgium
| | - Pierre A. Jacobs
- *Department of Microbial and Molecular Systems, Centre for Surface Chemistry and Catalysis, Katholieke Universiteit Leuven, Kasteelpark Arenberg 23, B-3001 Leuven, Belgium
| | - Frans C. De Schryver
- Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium; and
| | - Dirk E. De Vos
- *Department of Microbial and Molecular Systems, Centre for Surface Chemistry and Catalysis, Katholieke Universiteit Leuven, Kasteelpark Arenberg 23, B-3001 Leuven, Belgium
- To whom correspondence may be addressed. E-mail: or
| | - Johan Hofkens
- Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium; and
- To whom correspondence may be addressed. E-mail: or
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Shenoy D, Little S, Langer R, Amiji M. Poly(ethylene oxide)-modified poly(beta-amino ester) nanoparticles as a pH-sensitive system for tumor-targeted delivery of hydrophobic drugs. 1. In vitro evaluations. Mol Pharm 2006; 2:357-66. [PMID: 16196488 PMCID: PMC1350920 DOI: 10.1021/mp0500420] [Citation(s) in RCA: 156] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A representative poly(beta-amino ester) (PbAE) with biodegradable and pH-sensitive properties was used to formulate a nanoparticle-based dosage form for tumor-targeted paclitaxel delivery. The polymer undergoes rapid dissolution when the pH of the medium is less than 6.5 and hence is expected to release its contents at once within the acidic tumor microenvironment and endo/lysosome compartments of cells. PbAE nanoparticles were prepared by solvent displacement method and characterized for particle size, charge, and surface morphology. Pluronic F-108, a triblock copolymer of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO), was blended with PbAE to induce surface modification of the nanoparticles. In vitro cellular uptake of tritiated [(3)H]-paclitaxel in solution form and as a nanoparticulate formulation was studied in MDA-MB-231 human breast adenocarcinoma cells grown in 12-well plates. We also examined the intracellular degradation pattern of the formulations within the cells by estimating the drug release profile. Cytotoxicity assay was performed on the formulations at different doses and time intervals. Nanoparticles prepared from poly(epsilon-caprolactone) (PCL) that do not display pH-sensitive release behavior were used as control. Spherical nanoparticles having positive zeta potential ( approximately 40 mV) were obtained in the size range of 150-200 nm with PbAE. The PEO chains of the Pluronic were well-anchored within the nanomatrix as determined by electron spectroscopy for chemical analysis (ESCA). The intracellular accumulation of paclitaxel within tumor cells was significantly higher when administered in the nanoparticle formulations as compared to aqueous solution. Qualitative fluorescent microscopy confirmed the rapid release of the payload into the cytosol in the case of PbAE nanoparticles, while the integrity of the PCL nanoparticles remained intact. The cytotoxicity assay results showed significantly higher tumoricidal activity of paclitaxel when administered in the nanoparticle formulations. The cell-kill effect was maximal for paclitaxel-loaded PbAE nanoparticles when normalized with respect to intracellular drug concentrations. Thus, PEO-modified PbAE nanoparticles show tremendous potential as novel carriers of cytotoxic agents for achieving improved drug disposition and enhanced efficacy.
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Affiliation(s)
- Dinesh Shenoy
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA 02115
| | - Steven Little
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Robert Langer
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Mansoor Amiji
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA 02115
- *Author to whom correspondence should be addressed: Department of Pharmaceutical Sciences, Northeastern University, Boston, MA 02115. Tel: (617) 373-3137. Fax: (617) 373-8886. E-mail:
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Boens N, De Feyter S, Hofkens J, Viaene L, Van der Auweraer M. Frans De Schryver: forty years of photochemistry and photophysics. Chemphyschem 2005; 6:2215-7. [PMID: 16273573 DOI: 10.1002/cphc.200500424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Noel Boens
- Division of Molecular and Nanomaterials, Chemistry Department, K.U.Leuven, Celestijnenlaan 200 F, 3001 Heverlee, Leuven, Belgium
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Fredin NJ, Zhang J, Lynn DM. Surface analysis of erodible multilayered polyelectrolyte films: nanometer-scale structure and erosion profiles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:5803-11. [PMID: 15952826 DOI: 10.1021/la050596+] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Atomic force microscopy (AFM) and scanning electron microscopy (SEM) coupled with ellipsometry have been used to characterize the microscale and nanoscale structures of erodible multilayered films fabricated from degradable polyamine 1 and either sodium poly(styrene sulfonate) (SPS) or plasmid DNA. Striking differences were found in the topography, structures, and erosion profiles of these two materials upon incubation in PBS buffer at 37 degrees C. For films fabricated from SPS, AFM data are consistent with an erosion process that occurs uniformly without the generation of holes or pits over large, micrometer-scale areas. By contrast, films fabricated from plasmid DNA undergo structural rearrangements to present surface-bound particles ranging in size from 50 to 400 nm. Additional characterization of these particulate structures by SEM suggested that they are interpenetrated with or fused to underlying polyelectrolyte layers on the silicon surface, providing a potential mechanism to manipulate the adhesive forces with which these particles are bound to the surface. The erosion profile observed for polymer 1/SPS films suggests that it may be possible to design assemblies that release two film components with well-defined release kinetics. In the context of gene delivery, the presentation of condensed DNA as nanoparticles at these surfaces may be advantageous with respect to stimulating the internalization and processing of DNA by cells. A quantitative understanding of the factors influencing the fabrication, structure, and erosion profiles of these materials will be useful for the design of multilayered assemblies for specific applications in which controlled film erosion or the release of therapeutic materials is desired.
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Affiliation(s)
- Nathaniel J Fredin
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, Wisconsin 53706-1607, USA
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Gordon VD, Chen X, Hutchinson JW, Bausch AR, Marquez M, Weitz DA. Self-Assembled Polymer Membrane Capsules Inflated by Osmotic Pressure. J Am Chem Soc 2004; 126:14117-22. [PMID: 15506776 DOI: 10.1021/ja0474749] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We fabricate and characterize capsules that are composite membranes, made of a polymer network stabilized by adsorption to colloids and inflated by osmotic pressure from internal free polyelectrolyte; here, poly-l-lysine forms the network and inflates the capsules. To assess these capsules' properties and structure, we deform capsules using microcantilevers and use finite element modeling to describe these deformations. Additional experimental tests confirm the model's validity. These capsules' resilient response to mechanical forces indicates that loading and shear should be good triggers for the release of contents via deformation. The osmotic pressure inflating these capsules has the potential to trigger release of contents via deflation in response to changes in the capsules' environment; we demonstrate addition of salt as a trigger for deflating capsules. Because these capsules have a variety of release triggers available and the technique used to fabricate them is very flexible and allows high encapsulation efficiency, these capsules have very high potential for application in many areas.
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Affiliation(s)
- Vernita D Gordon
- Department of Physics and Division of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA
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Zhang J, Xu S, Kumacheva E. Polymer Microgels: Reactors for Semiconductor, Metal, and Magnetic Nanoparticles. J Am Chem Soc 2004; 126:7908-14. [PMID: 15212539 DOI: 10.1021/ja031523k] [Citation(s) in RCA: 566] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report a strategy for the production of materials with structural hierarchy. The approach employs polymer microgels as templates for the synthesis of semiconductor, metal, or magnetic nanoparticles (NPs). We show that NPs with predetermined dimensions and size-dependent properties can be synthesized by using a very delicate balance between the reaction conditions, the composition and the structure of microgel templates, and the concentration of NPs in the microgel. Postheat treatment of microgels doped with semiconductor nanoparticles reduces NP polydispersity and allows control of their photoluminescence. Microgel templates are particularly beneficial in the synthesis of polymer microspheres heavily loaded with monodisperse superparamagnetic Fe(3)O(4) NPs. Hybrid submicrometer-size microgels have promising potential applications in photonics, catalysis, and separation technologies.
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Affiliation(s)
- Jiguang Zhang
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, M5S 3H6, Canada
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Qi K, Ma Q, Remsen EE, Clark CG, Wooley KL. Determination of the Bioavailability of Biotin Conjugated onto Shell Cross-Linked (SCK) Nanoparticles. J Am Chem Soc 2004; 126:6599-607. [PMID: 15161288 DOI: 10.1021/ja039647k] [Citation(s) in RCA: 130] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Shell cross-linked nanoparticles (SCKs) presenting surface- and bioavailable biotin functional groups were synthesized via a mixed micelle methodology, whereby co-micellization of chain terminal biotinylated poly(acrylic acid)-b-poly(methyl acrylate) (PAA-b-PMA) and nonbiotinylated PAA-b-PMA were cross-linked in an intramicellar fashion within the shell layer of the mixed micelles, between the carboxylic acid groups of PAA and the amine functionalities of 2,2'-(ethylenedioxy)diethylamine. The hydrodynamic diameters (D(h)) of the micelles and the SCKs with different biotinylated block copolymer contents were determined by dynamic light scattering (DLS), and the dimensions of the SCKs were characterized with tapping-mode atomic force microscopy (AFM) and transmission electron microscopy (TEM). The amount of surface-available biotin was tuned by varying the stoichiometric ratio of the biotinylated PAA-b-PMA versus the nonbiotinylated PAA-b-PMA, as demonstrated with solution-state, binding interaction analyses, an avidin/HABA (avidin/4'-hydroxyazobenzene-2-carboxylic acid) competitive binding assay, and fluorescence correlation spectroscopy (FCS). The avidin/HABA assay found the amount of available biotin at the surface of the biotinylated SCK nanoparticles to increase with increasing biotin-terminated block copolymer incorporation, but to be less than 25% of the theoretical value. FCS measurements showed the same trend.
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Affiliation(s)
- Kai Qi
- Department of Chemistry, Washington University, One Brookings Drive, Saint Louis, Missouri 63130-4899, USA
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Vicinelli V, Ceroni P, Maestri M, Lazzari M, Balzani V, Lee SK, Heyst Jv JV, Vogtle F. Photochemical and photophysical properties of a poly(propylene amine) dendrimer functionalised with E-stilbene units. Org Biomol Chem 2004; 2:2207-13. [PMID: 15280957 DOI: 10.1039/b404463k] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A second generation poly(propylene amine) dendrimer functionalized at the periphery with eight E-stilbene and eight 4-tert-butylbenzenesulfonyl units has been prepared. The absorption spectrum, fluorescence spectrum and decay, E<==>Z photoisomerization, and photocyclization of the Z-isomer of the stilbene units have been investigated in air equilibrated acetonitrile solutions. For comparison purposes, a reference compound of the peripheral dendrimer units, namely 4-tert-butyl-N-propyl-N-(4-styryl-benzyl)-benzenesulfonamide, has also been studied. The quantum yield of the E-->Z photoisomerization reaction (0.30) and the fluorescence quantum yield of the E isomer (0.014) are substantially smaller for the units appended to the dendrimer compared to those of the reference compound (0.50 and 0.046, respectively). The presence of a red tail and the biexponential decay of the emission band of the dendrimer indicate formation of excimers between the stilbene units appended at the poly(propylene amine) dendritic structure. Under the experimental conditions used (lambda(exc)= 313 nm), a Z/E photostationary state (around 9 : 1 for both reference compound and dendrimer ) is reached in the time scale of minutes. On continuing irradiation, other photoreactions take place in the time scale of hours: the stilbene moiety of compound undergoes photocyclization to phenanthrene (quantum yield 0.015), whereas in dendrimer photocyclization to phenanthrene is accompanied by other processes, including a photoreaction involving the internal amine groups.
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Affiliation(s)
- Veronica Vicinelli
- Dipartimento di Chimica "G. Ciamician", Universita di Bologna, via Selmi 2, I-40126 Bologna, Italy
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Murthy N, Thng YX, Schuck S, Xu MC, Fréchet JMJ. A novel strategy for encapsulation and release of proteins: hydrogels and microgels with acid-labile acetal cross-linkers. J Am Chem Soc 2002; 124:12398-9. [PMID: 12381166 DOI: 10.1021/ja026925r] [Citation(s) in RCA: 295] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A new acid-labile acetal cross-linker was synthesized and used to prepare protein-loaded hydrogels and microgels. This cross-linker undergoes an acid-catalyzed degradation with a half-life of 5.5 min at pH 5.0 and 24 h at pH 7.4. Protein-loaded hydrogels were synthesized with this cross-linker, and their release profiles were measured as a function of pH. Hydrogels made with the acetal cross-linker release their contents in a pH-dependent manner. The acetal cross-linker was also used to synthesize microgels with sizes between 1 and 10 mum, a range suitable for phagocytosis. The unique acid sensitivity of the acetal cross-linker should make it a useful synthetic intermediate in the design of acid-sensitive drug or gene delivery systems.
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Affiliation(s)
- Niren Murthy
- Center for New Directions in Organic Synthesis, Department of Chemistry, University of California, Berkeley, California 94720-1460, USA
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Masuo S, Yoshikawa H, Asahi T, Masuhara H, Sato T, Jiang DL, Aida T. Repetitive Contraction and Swelling Behavior of Gel-like Wire-type Dendrimer Assemblies in Solution Layer by Photon Pressure of a Focused Near-infrared Laser Beam. J Phys Chem B 2002. [DOI: 10.1021/jp013367e] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Vögtle F, Gorka M, Hesse R, Ceroni P, Maestri M, Balzani V. Photochemical and photophysical properties of poly(propylene amine) dendrimers with peripheral naphthalene and azobenzene groups. Photochem Photobiol Sci 2002; 1:45-51. [PMID: 12659148 DOI: 10.1039/b106813j] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report the preparation, the absorption spectra, and the photophysical and photochemical properties in dichloromethane solution of four dendrimers of the poly(propylene amine) family (indicated by POPAM or PPI) functionalised with naphthalene and trans-azobenzene units. Each dendrimer Gn, where n = 1 to 4 is the generation number, comprises 2(n+1)-2 (i.e., 30 for G4) tertiary amine units in the interior and 2(n1) (i.e., 32 for G4) naphthalene and trans-azobenzene units in the periphery. For comparison purposes, the photophysical and photochemical properties of model compounds of the peripheral units have also been investigated. We have found that the fluorescence of the naphthalene units is quenched by the tertiary amines (via electron transfer) as well as by the trans-azobenzene units (via energy transfer). The quantum yields of the trans-->cis and cis-->trans photoisomerisation of the azobenzene units have been measured at various excitation wavelengths. Quenching of the fluorescence of the excited naphthalene unit by the trans- and cis-azobenzene units is accompanied by the sensitisation of the cis-->trans (but not of the trans-->cis) isomerisation. The rate constant of the thermal cis-->trans isomerisation of the azobenzene units has also been measured. Comparison of the results obtained for model compounds and for the G4 dendrimer shows that the dendritic structure favours the trans configuration of the azobenzene units ("dendritic effect"), presumably because it is less demanding in terms of space and causes less crowding on the dendrimer surface.
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Affiliation(s)
- Fritz Vögtle
- Kekul-Institut für Organische Chemie und Biochemie der Universität Bonn, Gerhard-Domagk Strasse 1, D-53121, Bonn, Germany.
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Lynn DM, Anderson DG, Putnam D, Langer R. Accelerated discovery of synthetic transfection vectors: parallel synthesis and screening of a degradable polymer library. J Am Chem Soc 2001; 123:8155-6. [PMID: 11506588 DOI: 10.1021/ja016288p] [Citation(s) in RCA: 283] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- D M Lynn
- Department of Chemical Engineering, Massachusetts Institute of Technology Cambridge, Massachusetts 02139, USA
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