Nicholas A. Peppas

Bio: Nicholas A. Peppas is an academic researcher from University of Texas at Austin. The author has contributed to research in topics: Self-healing hydrogels & Drug delivery. The author has an hindex of 141, co-authored 825 publications receiving 90533 citations. Previous affiliations of Nicholas A. Peppas include National Technical University & University of Texas System.

Analyzing polyaniline-poly(2-acrylamido-2-methylpropane sulfonic acid) biocompatibility with 3T3 fibroblasts.

Abstract: Conductive polymers can be utilized as unique functional elements in future intelligent biomaterials required for tissue engineering, cell stimulation and drug delivery. Research in these areas could be limited by established methods of conductive polymer synthesis which do not provide an easy route towards large scale processing of these materials. Typically, conductive polymers are highly insoluble in biocompatible solvents, and can be mechanically brittle, making their integration with biomaterials challenging. As an alternative, the use of a water-soluble conductive polymer for integration with biomaterials, a polyaniline template synthesized with poly(2-acrylamido-2-methylpropanesulfonic acid) (PANI-PAAMPSA), is proposed. To address key fundamental questions about the biocompatibility of this conductive polymer, cell cytotoxicity and proliferation assays have been performed on NIH 3T3 fibroblasts cultured on films of PANI-PAAMPSA. It was determined that the cell cultures maintained growth habits similar to those cultured on the control surfaces. Additionally, conductivity of the PANI-PAAMPSA films subsequent to exposure to the cell culture was demonstrated, indicating the materials retain functionality after cell growth. These results indicate that this type of template synthesized PANI could be successfully implemented as a functional, conductive biomaterial.

Tunable poly(methacrylic acid-co-acrylamide) nanoparticles through inverse emulsion polymerization.

Abstract: Environmentally responsive biomaterials have played key roles in the design of biosensors and drug delivery vehicles. Their physical response to external stimuli, such as temperature or pH, can transduce a signal or trigger the release of a drug. In this work, we designed a robust, highly tunable, pH-responsive nanoscale hydrogel system. We present the design and characterization of poly(methacrylic acid-co-acrylamide) hydrogel nanoparticles, crosslinked with methylenebisacrylamide, through inverse emulsion polymerization. The effects of polymerization parameters (i.e., identities and concentrations of monomer and surfactant) and polymer composition (i.e., weight fraction of ionic and crosslinking monomers) on the nanoparticles' bulk and environmentally responsive properties were determined. We generated uniform, spherical nanoparticles which, through modulation of crosslinking, exhibit a volume swelling of 1.77-4.07, relative to the collapsed state in an acidic environment. We believe our system has potential as a base platform for the targeted, injectable delivery of hydrophilic therapeutics. With equal importance, however, we hope that our systematic analysis of the individual impacts of polymerization and purification conditions on nanoparticle composition, morphology, and performance can be used to expedite the development of alternate hydrophilic nanomaterials for a range of biomedical applications. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1677-1686, 2018.

Matrix Effects on Interdiffusion at the Polystyrene and Poly(vinyl methyl ether) Interface

Abstract: The effect of polystyrene (PS) matrix relaxation on interdiffusion at a PS and poly(vinyl methyl ether) (PVME) interface was investigated with attenuated total internal reflectance infrared spectroscopy (ATR-FTIR) at 105 and 85 °C, corresponding to 5 °C above and 15 °C below the T g of PS, respectively. Monodisperse PS samples with M w of 3.0 x 10 6 and 1.05 x 10 5 were used to simulate relaxation in the PS matrix corresponding to chain reptation and constrained-release mechanisms, respectively. A binary blend of monodisperse PS samples consisting of short chains with M w of 3.0 x 10 4 and long chains with M w of 3.0 x 10 6 was used to simulate relaxation in the PS matrix by tube dilation. In the binary PS blend, the short chains were deuterated in order to monitor the concentration of each component independently. Non-Fickian diffusion was observed above and below the T g of the PS matrix. Above the T g of PS, interdiffusion was enhanced as the matrix relaxation mechanism changed from chain reptation to tube dilation to constrained release, consistent with the predicted relaxation time of these matrices. Below the T g of PS, interdiffusion was controlled by the rate of swelling of PS by PVME and interdiffusion was faster in the binary PS blend due to the reduced entanglement density between the long chains.

Distribution of glycosaminoglycans in consecutive layers of the rabbit aorta

Abstract: Transmural variations in various glycosaminoglycan (GAG) fractions were determined in adventitia-free thoracic aortas from rabbits. Total glycosaminoglycan concentration decreased from intima to outer media. These data are similar to total GAG concentration in bovine and human aortas as reported by others. There is a marked decrease in the concentration of the combined chondroitin sulfate-dermatan sulfate component with increasing distance from the endothelial surface. These transmural differences are linked to the possible variation of the diffusion coefficient of a diffusing solute as a function of distance, which can affect the concentration profile of the solute.

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

The Design and Analysis of Experiments

Abstract: THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

Harrison's Principles of Internal Medicine

Abstract: The 11th edition of Harrison's Principles of Internal Medicine welcomes Anthony Fauci to its editorial staff, in addition to more than 85 new contributors. While the organization of the book is similar to previous editions, major emphasis has been placed on disorders that affect multiple organ systems. Important advances in genetics, immunology, and oncology are emphasized. Many chapters of the book have been rewritten and describe major advances in internal medicine. Subjects that received only a paragraph or two of attention in previous editions are now covered in entire chapters. Among the chapters that have been extensively revised are the chapters on infections in the compromised host, on skin rashes in infections, on many of the viral infections, including cytomegalovirus and Epstein-Barr virus, on sexually transmitted diseases, on diabetes mellitus, on disorders of bone and mineral metabolism, and on lymphadenopathy and splenomegaly. The major revisions in these chapters and many

Understanding biophysicochemical interactions at the nano–bio interface

Abstract: Rapid growth in nanotechnology is increasing the likelihood of engineered nanomaterials coming into contact with humans and the environment. Nanoparticles interacting with proteins, membranes, cells, DNA and organelles establish a series of nanoparticle/biological interfaces that depend on colloidal forces as well as dynamic biophysicochemical interactions. These interactions lead to the formation of protein coronas, particle wrapping, intracellular uptake and biocatalytic processes that could have biocompatible or bioadverse outcomes. For their part, the biomolecules may induce phase transformations, free energy releases, restructuring and dissolution at the nanomaterial surface. Probing these various interfaces allows the development of predictive relationships between structure and activity that are determined by nanomaterial properties such as size, shape, surface chemistry, roughness and surface coatings. This knowledge is important from the perspective of safe use of nanomaterials.