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.

Effect of monomer type and dangling end size on polymer network synthesis

Abstract: The design of novel biomaterials for applications in biological recognition, drug delivery, or diagnostics requires a judicious choice of preparation conditions and methods for the production of well-characterized 3-dimensional structures, preferably by benign processes. In this work, the polymerization of poly(ethylene glycol) (PEG) methacrylates was examined by kinetic gelation modeling and kinetic analysis in order to ascertain the factors affecting the resulting structure. The kinetics of the polymerization and structure of the final polymer network are strongly affected by the length of the PEG graft chain. The propagation of the polymer chains becomes increasingly diffusion limited with the incorporation of longer PEG grafts. In addition, a more heterogeneous network consisting of numerous microgel regions is produced as the length of the PEG graft is increased. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3506–3519, 2003

Microcantilever sensing arrays from biodegradable, pH-responsive hydrogels.

Abstract: Biodegradable, pH-responsive hydrogels composed of poly(methacrylic acid) crosslinked with varying molar percentages of polycaprolactone diacrylate were synthesized. The equilibrium swelling properties of these pH-responsive materials were studied. Methods were developed to incorporate these novel hydrogels as sensing components in silicon-based microsensors. Extremely thin layers of hydrogels were prepared by photopolymerization atop silicon microcantilever arrays that served to transduce the pH-responsive volume change of the hydrogel into an optical signal. Organosilane chemistry allowed covalent adhesion of the hydrogel to the silicon beam. As the hydrogel swelled, the stress generated at the surface between the hydrogel and the silicon caused a beam deflection downward. The resulting sensor demonstrated a maximum sensitivity of 1 nm/5.7×10−5 pH unit. Sensors were tested in protein-rich solutions to mimic biological conditions and found to retain their high sensitivity. The existing theory was evaluated and developed to predict deflection of these composite cantilever beams.

Microparticle composition and method

Abstract: The invention relates to a cross-linked hydrogel composition in the form of substantially uniform microparticles and a method of preparation therefor. The hydrogel composition comprises a crosslinked polymer formed by free radical polymerization of olefin monomers comprising a C3-C6 unsaturated carboxylic acid and a water dispersible polyolefin crosslinking agent. The olefin monomers may further comprise a polyalkyleneglycol monoacrylate or momomethacrylate.

Analysis of drug distribution in hydrogels using fourier transform infrared microscopy.

Abstract: Purpose. The purpose of this work was to study solute (drug and protein)/polymer interactions that affect solute diffusion in and subsequent release from swellable dosage forms based on environmentally responsive, pH-sensitive polymer networks.

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.