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Akula SK, Exposito-Alonso D, Walsh CA. Shaping the brain: The emergence of cortical structure and folding. Dev Cell 2023; 58:2836-2849. [PMID: 38113850 PMCID: PMC10793202 DOI: 10.1016/j.devcel.2023.11.004] [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] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 04/08/2023] [Accepted: 11/10/2023] [Indexed: 12/21/2023]
Abstract
The cerebral cortex-the brain's covering and largest region-has increased in size and complexity in humans and supports higher cognitive functions such as language and abstract thinking. There is a growing understanding of the human cerebral cortex, including the diversity and number of cell types that it contains, as well as of the developmental mechanisms that shape cortical structure and organization. In this review, we discuss recent progress in our understanding of molecular and cellular processes, as well as mechanical forces, that regulate the folding of the cerebral cortex. Advances in human genetics, coupled with experimental modeling in gyrencephalic species, have provided insights into the central role of cortical progenitors in the gyrification and evolutionary expansion of the cerebral cortex. These studies are essential for understanding the emergence of structural and functional organization during cortical development and the pathogenesis of neurodevelopmental disorders associated with cortical malformations.
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Affiliation(s)
- Shyam K Akula
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA, USA; Departments of Pediatrics and Neurology, Harvard Medical School, Boston, MA, USA; Allen Discovery Center for Human Brain Evolution, Boston Children's Hospital and Harvard Medical School, Boston, MA, USA; Howard Hughes Medical Institute, Chevy Chase, Maryland, USA
| | - David Exposito-Alonso
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA, USA; Departments of Pediatrics and Neurology, Harvard Medical School, Boston, MA, USA; Allen Discovery Center for Human Brain Evolution, Boston Children's Hospital and Harvard Medical School, Boston, MA, USA; Howard Hughes Medical Institute, Chevy Chase, Maryland, USA
| | - Christopher A Walsh
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA, USA; Departments of Pediatrics and Neurology, Harvard Medical School, Boston, MA, USA; Allen Discovery Center for Human Brain Evolution, Boston Children's Hospital and Harvard Medical School, Boston, MA, USA; Howard Hughes Medical Institute, Chevy Chase, Maryland, USA.
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Sburlati S, Gustafson A, Kahr B. Comparative rotatory power of bent and twisted polyynes. Chirality 2023; 35:838-845. [PMID: 37226985 DOI: 10.1002/chir.23579] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2023] [Revised: 04/29/2023] [Accepted: 05/03/2023] [Indexed: 05/26/2023]
Abstract
Linear polyynes of the formula C18 H2 (symmetry D∞h ) were bent in silico by progressively introducing CCC angles less than 180°. The bent structures (symmetry C2v ) were then twisted by introducing torsion angles across the CCCC segments by as much as 60°. The gyration tensors of these 19 structures (linear, bent, and twisted) were computed by linear response methods. Bending is massively generative of optical activity in oriented structures, even achiral structures, whereas twisting in conjunction with bending, serves to linearize the molecules and diminish maximally observable optical activity. This computational exercise is intended to unbind the infelicitous linkage of optical activity and chirality, which is only meaningful in isotropic media. Although bent structures are not optically active in solution-the spatial average of the optical activity is necessarily zero-solution measurements that deliver the spatial averages are a special class of measurements, albeit the overwhelmingly most common chiroptical measurements, that prejudice our common understanding of how π-conjugated structures generate gyration. Bending is far more effective than twisting at generating optical activity along some directions for oriented structures. The respective contributions from the transition electric dipole-magnetic dipole polarizability and the transition electric dipole-electric quadrupole polarizability are compared.
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Affiliation(s)
- Sophia Sburlati
- Department of Chemistry and Molecular Design Institute, New York University, New York City, New York, USA
| | - Afton Gustafson
- Department of Chemistry and Molecular Design Institute, New York University, New York City, New York, USA
| | - Bart Kahr
- Department of Chemistry and Molecular Design Institute, New York University, New York City, New York, USA
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Hagege R, Krajden Haratz K, Malinger G, Ben-Sira L, Leibovitz Z, Heron D, Burglen L, Birnbaum R, Valence S, Keren B, Blumkin L, Jouannic JM, Lerman-Sagie T, Garel C. Spectrum of brain malformations in fetuses with mild tubulinopathy. Ultrasound Obstet Gynecol 2023; 61:740-748. [PMID: 36484554 DOI: 10.1002/uog.26140] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 11/15/2022] [Accepted: 11/24/2022] [Indexed: 06/03/2023]
Abstract
OBJECTIVE To report on a large cohort of fetuses with mild forms of tubulinopathy and to define prenatal ultrasound and magnetic resonance imaging (MRI) features that can facilitate prenatal diagnosis. METHODS This was a retrospective multicenter study of fetuses diagnosed between January 2007 and February 2022 with a mild tubulinopathy (without lissencephaly or microlissencephaly). We collected and reviewed brain imaging and genetic data, and defined major criteria as findings observed in ≥ 70% of the patients and minor criteria as those observed in ≥ 50% but < 70% of the patients. RESULTS Our cohort included 34 fetuses. The mean gestational age at ultrasound screening, when suspicion of a central nervous system anomaly was first raised, was 24.2 (range, 17-33) weeks. Callosal anomalies (n = 19 (56%)) and abnormal ventricles (n = 18 (53%)) were the main reasons for referral. The mean gestational age at neurosonography was 28.3 (range, 23-34) weeks and that at MRI was 30.2 (range, 24-35) weeks. Major ultrasound criteria were midline distortion, ventricular asymmetry, dysmorphic and/or dilated frontal horn(s) and abnormal sulcation. Minor ultrasound criteria were distortion of the cavum septi pellucidi, abnormal corpus callosum, absent or asymmetric olfactory sulci, ventriculomegaly and basal ganglia dysmorphism. Major MRI criteria were midline distortion, distortion of the cavum septi pellucidi, ventricular asymmetry, dilatation (generally unilateral) and/or distortion, dysmorphic and/or dilated frontal horn(s) and abnormal sulcation (mainly dysgyria). Minor MRI criteria were absent or asymmetric olfactory sulci, abnormal bulge of the pons, anteroposterior diameter of the pons ≤ 5th centile and brainstem asymmetry. A mutation was found in TUBB3 (44.1% of cases), TUBB (23.5%), TUBB2B (14.7%) or TUBA1A (17.6%). The mutation was inherited from a parent in 18/34 cases. The pregnancy was terminated in 23/34 cases. CONCLUSIONS Prenatal diagnosis of mild forms of tubulinopathy is possible but challenging. We have defined, in this large series of fetuses, major and minor criteria that can help identify this entity in utero. Most findings can be visualized on ultrasound. This evaluation is also important for prenatal counseling. Once a prenatal diagnosis of mild tubulinopathy is suspected, the family members should be referred for exome sequencing and MRI. © 2022 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.
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Affiliation(s)
- R Hagege
- Department of Radiology, Armand Trousseau Hospital, AP-HP, Sorbonne University, Paris, France
- Department of Obstetrics and Gynecology, Samson Assuta Ashdod Hospital, Ashdod, Israel
- Faculty of Medicine, Ben Gurion University, Beer Sheva, Israel
| | - K Krajden Haratz
- Division of Ultrasound in Obstetrics and Gynecology, Lis Maternity and Women's Hospital, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - G Malinger
- Division of Ultrasound in Obstetrics and Gynecology, Lis Maternity and Women's Hospital, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - L Ben-Sira
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- Department of Radiology, Division of Pediatric Radiology, Dana Children's Hospital, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
| | - Z Leibovitz
- Obstetrics-Gynecology Ultrasound Unit, Bnai-Zion Medical Center, Haifa, Israel
- Rappaport Faculty of Medicine, Technion, Israel Institute of Technology, Haifa, Israel
- Fetal Neurology Clinic, Obstetrics-Gynecology Ultrasound Unit, Department of Obstetrics and Gynecology, Wolfson Medical Center, Holon, Israel
| | - D Heron
- Department of Genetics, Division of Medical Genetics, Reference Center for Rare Diseases and Intellectual Deficiencies of Rare Causes, Pitié-Salpêtrière Hospital, AP-HP, Sorbonne University, Paris, France
| | - L Burglen
- Department of Genetics, Reference Center for Cerebellar Malformations and Congenital Diseases, Armand Trousseau Hospital, AP-HP, Sorbonne University, Paris, France
| | - R Birnbaum
- Division of Ultrasound in Obstetrics and Gynecology, Lis Maternity and Women's Hospital, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - S Valence
- Department of Pediatric Neurology, Reference Center for Rare Diseases and Intellectual Deficiencies of Rare Causes, Armand Trousseau Hospital, AP-HP, Sorbonne University, Paris, France
| | - B Keren
- Department of Genetics, Pitié-Salpêtrière Hospital, AP-HP, Sorbonne University, Paris, France
| | - L Blumkin
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- Fetal Neurology Clinic, Pediatric Neurology Unit, Magen Center for Rare Diseases, Wolfson Medical Center, Holon, Israel
| | - J-M Jouannic
- Fetal Medicine Department, Armand Trousseau Hospital, AP-HP, Sorbonne University, Paris, France
| | - T Lerman-Sagie
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- Fetal Neurology Clinic, Pediatric Neurology Unit, Magen Center for Rare Diseases, Wolfson Medical Center, Holon, Israel
| | - C Garel
- Department of Radiology, Reference Center for Cerebellar Malformations and Congenital Diseases, Armand Trousseau Hospital, AP-HP, Sorbonne University, Paris, France
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Rodriguez-Sibaja MJ, Villar J, Ohuma EO, Napolitano R, Heyl S, Carvalho M, Jaffer YA, Noble JA, Oberto M, Purwar M, Pang R, Cheikh Ismail L, Lambert A, Gravett MG, Salomon LJ, Drukker L, Barros FC, Kennedy SH, Bhutta ZA, Papageorghiou AT. Fetal cerebellar growth and Sylvian fissure maturation: international standards from Fetal Growth Longitudinal Study of INTERGROWTH-21 st Project. Ultrasound Obstet Gynecol 2021; 57:614-623. [PMID: 32196791 DOI: 10.1002/uog.22017] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Revised: 02/26/2020] [Accepted: 03/07/2020] [Indexed: 06/10/2023]
Abstract
OBJECTIVE To construct international ultrasound-based standards for fetal cerebellar growth and Sylvian fissure maturation. METHODS Healthy, well nourished pregnant women, enrolled at < 14 weeks' gestation in the Fetal Growth Longitudinal Study (FGLS) of INTERGROWTH-21st , an international multicenter, population-based project, underwent serial three-dimensional (3D) fetal ultrasound scans every 5 ± 1 weeks until delivery in study sites located in Brazil, India, Italy, Kenya and the UK. In the present analysis, only those fetuses that underwent developmental assessment at 2 years of age were included. We measured the transcerebellar diameter and assessed Sylvian fissure maturation using two-dimensional ultrasound images extracted from available 3D fetal head volumes. The appropriateness of pooling data from the five sites was assessed using variance component analysis and standardized site differences. For each Sylvian fissure maturation score (left or right side), mean gestational age and 95% CI were calculated. Transcerebellar diameter was modeled using fractional polynomial regression, and goodness of fit was assessed. RESULTS Of those children in the original FGLS cohort who had developmental assessment at 2 years of age, 1130 also had an available 3D ultrasound fetal head volume. The sociodemographic characteristics and pregnancy/perinatal outcomes of the study sample confirmed the health and low-risk status of the population studied. In addition, the fetuses had low morbidity and adequate growth and development at 2 years of age. In total, 3016 and 2359 individual volumes were available for transcerebellar-diameter and Sylvian-fissure analysis, respectively. Variance component analysis and standardized site differences showed that the five study populations were sufficiently similar on the basis of predefined criteria for the data to be pooled to produce international standards. A second-degree fractional polynomial provided the best fit for modeling transcerebellar diameter; we then estimated gestational-age-specific 3rd , 50th and 97th smoothed centiles. Goodness-of-fit analysis comparing empirical centiles with smoothed centile curves showed good agreement. The Sylvian fissure increased in maturation with advancing gestation, with complete overlap of the mean gestational age and 95% CIs between the sexes for each development score. No differences in Sylvian fissure maturation between the right and left hemispheres were observed. CONCLUSION We present, for the first time, international standards for fetal cerebellar growth and Sylvian fissure maturation throughout pregnancy based on a healthy fetal population that exhibited adequate growth and development at 2 years of age. © 2020 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.
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Affiliation(s)
- M J Rodriguez-Sibaja
- Nuffield Department of Women's & Reproductive Health, University of Oxford, Oxford, UK
- Oxford Maternal & Perinatal Health Institute, Green Templeton College, University of Oxford, Oxford, UK
- Maternal-Fetal Medicine Department, National Institute of Perinatology, Mexico City, Mexico
| | - J Villar
- Nuffield Department of Women's & Reproductive Health, University of Oxford, Oxford, UK
- Oxford Maternal & Perinatal Health Institute, Green Templeton College, University of Oxford, Oxford, UK
| | - E O Ohuma
- Nuffield Department of Women's & Reproductive Health, University of Oxford, Oxford, UK
- Oxford Maternal & Perinatal Health Institute, Green Templeton College, University of Oxford, Oxford, UK
- Centre for Statistics in Medicine, Botnar Research Centre, University of Oxford, Oxford, UK
| | - R Napolitano
- Nuffield Department of Women's & Reproductive Health, University of Oxford, Oxford, UK
| | - S Heyl
- Nuffield Department of Women's & Reproductive Health, University of Oxford, Oxford, UK
| | - M Carvalho
- Faculty of Health Sciences, Aga Khan University, Nairobi, Kenya
| | - Y A Jaffer
- Department of Family & Community Health, Ministry of Health, Muscat, Sultanate of Oman
| | - J A Noble
- Department of Engineering Science, Institute of Biomedical Engineering, University of Oxford, Oxford, UK
| | - M Oberto
- S.C. Ostetricia 2U, Città della Salute e della Scienza di Torino, Turin, Italy
| | - M Purwar
- Nagpur INTERGROWTH-21st Research Centre, Ketkar Hospital, Nagpur, India
| | - R Pang
- School of Public Health, Peking University, Beijing, China
| | - L Cheikh Ismail
- Nuffield Department of Women's & Reproductive Health, University of Oxford, Oxford, UK
- Clinical Nutrition and Dietetics Department, University of Sharjah, Sharjah, United Arab Emirates
| | - A Lambert
- Nuffield Department of Women's & Reproductive Health, University of Oxford, Oxford, UK
- Oxford Maternal & Perinatal Health Institute, Green Templeton College, University of Oxford, Oxford, UK
| | - M G Gravett
- Departments of Obstetrics & Gynecology and of Public Health, University of Washington, Seattle, WA, USA
| | - L J Salomon
- Department of Obstetrics and Fetal Medicine, Hôpital Necker Enfants Malades, Université Paris Descartes, Paris, France
| | - L Drukker
- Nuffield Department of Women's & Reproductive Health, University of Oxford, Oxford, UK
- Oxford Maternal & Perinatal Health Institute, Green Templeton College, University of Oxford, Oxford, UK
| | - F C Barros
- Programa de Pós-Graduação em Saúde e Comportamento, Universidade Católica de Pelotas, Pelotas, Brazil
| | - S H Kennedy
- Nuffield Department of Women's & Reproductive Health, University of Oxford, Oxford, UK
- Oxford Maternal & Perinatal Health Institute, Green Templeton College, University of Oxford, Oxford, UK
| | - Z A Bhutta
- Center for Global Child Health, Hospital for Sick Children, Toronto, Canada
| | - A T Papageorghiou
- Nuffield Department of Women's & Reproductive Health, University of Oxford, Oxford, UK
- Oxford Maternal & Perinatal Health Institute, Green Templeton College, University of Oxford, Oxford, UK
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Mahalingam S, Huo S, Homer-Vanniasinkam S, Edirisinghe M. Generation of Core-Sheath Polymer Nanofibers by Pressurised Gyration. Polymers (Basel) 2020; 12:E1709. [PMID: 32751517 PMCID: PMC7464397 DOI: 10.3390/polym12081709] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2020] [Revised: 07/13/2020] [Accepted: 07/14/2020] [Indexed: 02/06/2023] Open
Abstract
The ability to generate core-sheath bicomponent polymer nanofibers in a single-step with scale-up possibilities is demonstrated using pressurised gyration manufacturing. This is the first time that nanofiber containing more than one polymer having a core-sheath configuration has been generated in this way. Water-soluble polymers polyethylene oxide (PEO) and polyvinyl pyrrolidone (PVP) are used as the core and sheath layers, respectively. Core-sheath nanofibers with a diameter in the range of 331 to 998 nm were spun using 15 wt % PEO and 15 wt % PVP polymer solutions. The forming parameters, working pressure and rotating speed, had a significant influence on the size, size distribution and the surface morphology of the nanofibers generated. Overall, fibre size decreased with increasing working pressure and rotating speed. The fibre size was normally distributed in all cases, with 0.2 MPa working pressure in particular showing narrower distribution. The fibre size distributions for 0.1 and 0.3 MPa working pressure were broader and a mean fibre size of 331 nm was obtained in the latter case. The fibre size was evenly distributed and narrower for rotating speeds of 2000 and 4000 RPMs. The distribution was broader for rotating speed of 6000 RPM with a mean value obtained at 430 nm. Continuous, smooth and bead-free fibre morphologies were obtained in each case. The fibre cross-section analysis using a focused ion beam machine showed a solid core surrounded by a sheath layer. Our findings demonstrate that the pressurised gyration could be used to produce core-sheath polymer nanofibers reliably and cost-effectively with scale-up possibilities (~4 kg h-1).
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Affiliation(s)
| | - Suguo Huo
- London Centre for Nanotechnology, University College London, London WC1H 0AH, UK;
| | | | - Mohan Edirisinghe
- Department of Mechanical Engineering, University College London, London WC1E 7JE, UK; (S.M.); (S.H.-V.)
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Böing L, Heun F, Gasse H. The contribution of the middle cerebral artery and callosal artery to the vascularisation of the Facies convexa of the brain in horses with reference to the equine-specific cartographic pattern of the neopallium. Folia Morphol (Warsz) 2021; 80:237-47. [PMID: 32639577 DOI: 10.5603/FM.a2020.0065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 05/23/2020] [Accepted: 05/25/2020] [Indexed: 11/25/2022]
Abstract
BACKGROUND The extremely complex surface architecture of the equine brain does not allow a uniform transfer of anatomical data from other mammalian species, e.g., dog or cat. Rather, a special approach is required to elucidate the equine-specific patterns of cerebral vascular ramifications. Therefore, a novel cartographic system was applied. Prior attention was paid to the A. cerebri media (MCA) and to the A. corporis callosi (CA), as they spread over the widest part of the neopallium's Facies convexa (i.e. the lateral and dorsal surface), thus being of particular interest in terms of surgical treatment of trauma of the skull and brain. MATERIALS AND METHODS The brains of 17 adult warmblood horses were studied. The neopallium's Facies convexa was subdivided into 15 sectors clearly delineated by the primary sulci and by related auxiliary lines. The courses and destinations of main branches (= branches of 1st or 2nd order, with a minimum calibre of 0.75 mm) of MCA and CA were topographically analysed by means of superimposed graphical sketches. RESULTS The MCA had six main branches (numbered in rostrocaudal direction); the CA had seven main branches. The main branches of the MCA spread over the widest part of the Facies convexa, but never reached the rostral pole and the caudal pole of the neopallium. Clearly, the main branches of CA proceeded from the hemisphere's medial side across the Margo dorsalis cerebri, thus supplying rostrodorsal and dorsal sectors of the Facies convexa. CONCLUSIONS The topographical analysis of the vascular ramification patterns (regions of residence) in combination with the cartographic system of sectors of the neopallium respected the equine-specific surface architecture. It highlighted the distinct vascular supply areas and the particular multiple-supply situations especially in sectors presumably related to the equine area motorica.
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Yokoyama K, Brown K, Shevlin P, Jenkins J, D'Ambrosio E, Ralbovsky N, Battaglia J, Deshmukh I, Ichiki A. Examination of Adsorption Orientation of Amyloidogenic Peptides Over Nano-Gold Colloidal Particle Surfaces. Int J Mol Sci 2019; 20:E5354. [PMID: 31661810 DOI: 10.3390/ijms20215354] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 10/14/2019] [Accepted: 10/23/2019] [Indexed: 01/12/2023] Open
Abstract
The adsorption of amyloidogenic peptides, amyloid beta 1–40 (Aβ1–40), alpha-synuclein (α-syn), and beta 2 microglobulin (β2m), was attempted over the surface of nano-gold colloidal particles, ranging from d = 10 to 100 nm in diameter (d). The spectroscopic inspection between pH 2 and pH 12 successfully extracted the critical pH point (pHo) at which the color change of the amyloidogenic peptide-coated nano-gold colloids occurred due to aggregation of the nano-gold colloids. The change in surface property caused by the degree of peptide coverage was hypothesized to reflect the ΔpHo, which is the difference in pHo between bare gold colloids and peptide coated gold colloids. The coverage ratio (Θ) for all amyloidogenic peptides over gold colloid of different sizes was extracted by assuming Θ = 0 at ΔpHo = 0. Remarkably, Θ was found to have a nano-gold colloidal size dependence, however, this nano-size dependence was not simply correlated with d. The geometric analysis and simulation of reproducing Θ was conducted by assuming a prolate shape of all amyloidogenic peptides. The simulation concluded that a spiking-out orientation of a prolate was required in order to reproduce the extracted Θ. The involvement of a secondary layer was suggested; this secondary layer was considered to be due to the networking of the peptides. An extracted average distance of networking between adjacent gold colloids supports the binding of peptides as if they are “entangled” and enclosed in an interfacial distance that was found to be approximately 2 nm. The complex nano-size dependence of Θ was explained by available spacing between adjacent prolates. When the secondary layer was formed, Aβ1–40 and α-syn possessed a higher affinity to a partially negative nano-gold colloidal surface. However, β2m peptides tend to interact with each other. This difference was explained by the difference in partial charge distribution over a monomer. Both Aβ1–40 and α-syn are considered to have a partial charge (especially δ+) distribution centering around the prolate axis. The β2m, however, possesses a distorted charge distribution. For a lower Θ (i.e., Θ <0.5), a prolate was assumed to conduct a gyration motion, maintaining the spiking-out orientation to fill in the unoccupied space with a tilting angle ranging between 5° and 58° depending on the nano-scale and peptide coated to the gold colloid.
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Abstract
A novel class of ultra-thin fibres, which affect microbial growth, were explored. The microbial properties of poly(methyl methacrylate) fibres containing 2, 4 and 8 wt% of graphene nanoplatelets (GNPs) were studied. GNPs were dispersed in a polymeric solution and processed using pressurized gyration. Electron microscopy was used to characterize GNP and fibre morphology. Scanning electron microscopy revealed the formation of beaded porous fibres. GNP concentration was found to dictate fibre morphology. As the GNP concentration increased, the average fibre diameter increased from 0.75 to 2.71 µm, while fibre porosity decreased. Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa were used to investigate the properties of 2, 4 and 8 wt% GNP-loaded fibres. GNP-loaded fibres (0 wt%) were used as the negative control. The fibres were incubated for 24 h with the bacteria; bacterial colony-forming units were enumerated by adopting the colony-counting method. The presence of 2 and 4 wt% GNP-loaded fibres promoted microbial growth, while 8 wt% GNP-loaded fibres showed antimicrobial activity. These results indicate that the minimum inhibitory concentration of GNPs required within a fibre is 8 wt%.
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Affiliation(s)
- Rupy Kaur Matharu
- Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE, UK
- Department of Civil, Environmental & Geomatic Engineering, University College London, Chadwick Building, Gower Street, London WC1E 6BT, UK
| | - Harshit Porwal
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Lena Ciric
- Department of Civil, Environmental & Geomatic Engineering, University College London, Chadwick Building, Gower Street, London WC1E 6BT, UK
| | - Mohan Edirisinghe
- Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE, UK
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Murphy VL, Farfan C, Kahr B. Chiroptical structure-property relations in cyclo[18]carbon and its in silico hydrogenation products. Chirality 2018; 30:325-331. [PMID: 29315836 DOI: 10.1002/chir.22817] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Revised: 12/07/2017] [Accepted: 12/08/2017] [Indexed: 11/11/2022]
Abstract
The anisotropy of the optical activity of cyclo[18]carbon (C18 ), fully hydrogenated C18 (C18 H36 ), and 26 hydrogenated compounds of intermediate composition, C18 H2n , n = 1,2…17, were computed. These compounds were selected because they resemble loops of wire. The maximum gyration for acetylenic and cumulenic subgroups of compounds was linearly proportional to the product of the geometric area over which the charge can circulate, multiplied by the largest separation between carbon atoms on opposing sides of the loops. These geometric quantities can be likened to transition magnetic dipole moments and transition electric dipole moments, respectively, that can be generated in electronic excitations and which contribute in the main to nonresonant optical activity. The correlation between a computed geometric product of distance and area, and a quantum chemical property, establishes that chiroptical structure-activity relationships can be well established for judiciously chosen series of comparatively large compounds.
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Affiliation(s)
- Veronica L Murphy
- Department of Chemistry and Molecular Design Institute, New York University, New York City, New York, USA
| | - Camille Farfan
- Department of Chemistry and Molecular Design Institute, New York University, New York City, New York, USA
| | - Bart Kahr
- Department of Chemistry and Molecular Design Institute, New York University, New York City, New York, USA.,Department of Advanced Science and Engineering, Waseda University, Tokyo, Japan
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Illangakoon UE, Mahalingam S, Matharu RK, Edirisinghe M. Evolution of Surface Nanopores in Pressurised Gyrospun Polymeric Microfibers. Polymers (Basel) 2017; 9:polym9100508. [PMID: 30965811 PMCID: PMC6418950 DOI: 10.3390/polym9100508] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [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: 09/19/2017] [Revised: 10/02/2017] [Accepted: 10/06/2017] [Indexed: 01/09/2023] Open
Abstract
The selection of a solvent or solvent system and the ensuing polymer–solvent interactions are crucial factors affecting the preparation of fibers with multiple morphologies. A range of poly(methylmethacrylate) fibers were prepared by pressurised gyration using acetone, chloroform, N,N-dimethylformamide (DMF), ethyl acetate and dichloromethane as solvents. It was found that microscale fibers with surface nanopores were formed when using chloroform, ethyl acetate and dichloromethane and poreless fibers were formed when using acetone and DMF as the solvent. These observations are explained on the basis of the physical properties of the solvents and mechanisms of pore formation. The formation of porous fibers is caused by many solvent properties such as volatility, solubility parameters, vapour pressure and surface tension. Cross-sectional images show that the nanopores are only on the surface of the fibers and they were not inter-connected. Further, the results show that fibers with desired nanopores (40–400 nm) can be prepared by carefully selecting the solvent and applied pressure in the gyration process.
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Affiliation(s)
- U Eranka Illangakoon
- Department of Mechanical Engineering, University College London, London WC1E 7JE, UK.
| | | | - Rupy K Matharu
- Department of Mechanical Engineering, University College London, London WC1E 7JE, UK.
| | - Mohan Edirisinghe
- Department of Mechanical Engineering, University College London, London WC1E 7JE, UK.
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11
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Martin AT, Nichols SM, Li S, Tan M, Kahr B. Double cone of eigendirections in optically active ethylenediammonium selenate crystals. J Appl Crystallogr 2017; 50:1117-1124. [PMID: 28808435 DOI: 10.1107/s1600576717007865] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Accepted: 05/26/2017] [Indexed: 11/10/2022] Open
Abstract
Circular birefringence (CB) is generally responsible for only a small perturbation to the state of light polarization in crystals that also exhibit linear birefringence (LB). As such, the magnetoelectric tensor of gyration, which gives rise to CB and optical activity, is less well determined than the electric permittivity tensor in optical models of the Mueller matrix. To visualize the effect of the magnetoelectric tensor on polarimetric measurements, reported here are experimental mappings of the Mueller matrix and of the CB in a new chiral crystal with accidental null LB at an accessible optical frequency. Single crystals of ethylenediammonium selenate (EDSeO4) were synthesized and characterized by X-ray diffraction and Mueller matrix measurements in transmission and reflection. The crystals are isomorphous with the corresponding sulfate salt. They are tetragonal, space group P41(3)212. The constitutive relations of EDSeO4 were recovered using a partial wave summation of incoherent reflections. The extraordinary and ordinary refractive indices cross at 364 nm (3.41 eV), a scenario commonly called the 'isotropic point' or 'iso-index point'. At this wavelength, the magnetoelectric tensor fully describes the polarization transformation, giving rise to a double cone of eigendirections.
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Affiliation(s)
| | - Shane M Nichols
- Department of Chemistry, New York University, New York, NY 10003, USA
| | - Sichao Li
- Department of Chemistry, New York University, New York, NY 10003, USA
| | - Melissa Tan
- Department of Chemistry, New York University, New York, NY 10003, USA
| | - Bart Kahr
- Department of Chemistry, New York University, New York, NY 10003, USA.,Department of Advanced Science and Engineering, Waseda University, Tokyo 162-8480, Japan
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12
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Zhang S, Karaca BT, VanOosten SK, Yuca E, Mahalingam S, Edirisinghe M, Tamerler C. Coupling Infusion and Gyration for the Nanoscale Assembly of Functional Polymer Nanofibers Integrated with Genetically Engineered Proteins. Macromol Rapid Commun 2015; 36:1322-8. [PMID: 26033345 PMCID: PMC5215549 DOI: 10.1002/marc.201500174] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [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: 03/23/2015] [Revised: 04/22/2015] [Indexed: 12/26/2022]
Abstract
Nanofibers featuring functional nanoassemblies show great promise as enabling constituents for a diverse range of applications in areas such as tissue engineering, sensing, optoelectronics, and nanophotonics due to their controlled organization and architecture. An infusion gyration method is reported that enables the production of nanofibers with inherent biological functions by simply adjusting the flow rate of a polymer solution. Sufficient polymer chain entanglement is obtained at Berry number > 1.6 to make bead‐free fibers integrated with gold nanoparticles and proteins, in the diameter range of 117–216 nm. Integration of gold nanoparticles into the nanofiber assembly is followed using a gold‐binding peptide tag genetically conjugated to red fluorescence protein (DsRed). Fluorescence microscopy analysis corroborated with Fourier transform infrared spectroscopy (FTIR) data confirms the integration of the engineered red fluorescence protein with the nanofibers. The gold nanoparticle decorated nanofibers having red fluorescence protein as an integral part keep their biological functionality including copper‐induced fluorescence quenching of the DsRed protein due to its selective Cu+2 binding. Thus, coupling the infusion gyration method in this way offers a simple nanoscale assembly approach to integrate a diverse repertoire of protein functionalities into nanofibers to generate biohybrid materials for imaging, sensing, and biomaterial applications.
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Affiliation(s)
- Siqi Zhang
- Department of Mechanical Engineering, University College London, Torrington Place, London, WC1E 7JE, UK
| | - Banu Taktak Karaca
- Bioengineering Research Center (BERC), Department of Mechanical Engineering, University of Kansas (KU), Lawrence, KS, 66045, USA
| | - Sarah Kay VanOosten
- Bioengineering Research Center (BERC), Department of Mechanical Engineering, University of Kansas (KU), Lawrence, KS, 66045, USA
| | - Esra Yuca
- Bioengineering Research Center (BERC), Department of Mechanical Engineering, University of Kansas (KU), Lawrence, KS, 66045, USA
| | | | - Mohan Edirisinghe
- Department of Mechanical Engineering, University College London, Torrington Place, London, WC1E 7JE, UK
| | - Candan Tamerler
- Bioengineering Research Center (BERC), Department of Mechanical Engineering, University of Kansas (KU), Lawrence, KS, 66045, USA
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