Peptide and protein therapeutics are highly effective for the treatment and management of numerous diseases. Despite this, their clinical potential is underutilized mainly due to drawbacks inherent to many native proteins such as poor stability, immunogenicity, and short pharmacokinetics. These issues cause a multitude of challenges in manufacturing, formulation, transportation, and administration. Ideally, peptide and protein therapeutics are shelf stable and are able to be administered in its native state through a minimally invasive method. My research focuses on 1) the exploration of different polymeric models in response to various stimuli to elucidate mechanisms behind certain drug delivery vehicles, 2) the sustained release of therapeutic peptide glucagon through a glucose-responsive hydrogel for the prevention of hypoglycemia, 3) the site-selective conjugation of a degradable, zwitterionic polymer to a model protein, and 4) the investigation of how polymer tacticity affects biological function through the conjugation of regio-and sequence-defined macromolecules to a model protein. Chapter 1 discusses three different strategies Stimuli-responsive nanoparticles, particularly those that respond to two different environmental cues, are useful materials in drug delivery. In chapter 2, the size-response of nanogels based on two different polymers, poly(N-isopropylacrylamide) p(NIPAM) and poly(oligo(ethylene glycol) methyl ether methacrylate) (PEGMA), to temperature and glucose concentration changes was investigated. The nanogels were prepared by precipitation polymerization, 114 nm and 169 nm for pNIPAM and PEGMA at 37 C, respectively, and characterized by proton nuclear magnetic resonance and infrared spectroscopies. Both nanogels underwent a volume phase transition in biologically relevant ranges upon heating. Incorporation of 2-aminophenylboronic acid enabled glucose-binding, resulting in a shift of the volume phase transition temperature (VPTT) of both nanogels as assessed by differential scanning calorimetry (DSC) and turbidity measurements. P(NIPAM) nanogel demonstrated a predictable decrease in size in response to both increase of temperature and glucose. PEGMA nanogel showed a predictable decrease in size to increasing temperature and but exhibited a surprising increase then decease in size to increasing concentrations of glucose.Glucagon is a peptide hormone used in the treatment of hypoglycemia. Unlike its counterpart insulin, glucagon has only started garnering interest in the past few decades. While recent advances have introduced user friendly formulations for glucagon administration, there remain no glucagon formulations on the market intended for combating nocturnal hypoglycemia. Chapter 3 details the sustained release of native glucagon using a glucose- and thermo-responsive hydrogel. RAFT polymerization was used to create PEG-b-p(NIPAM-co-2-APBA) polymers which were subsequently crosslinked using glucose. Polymer size, PEG length, boronic acid incorporation, and polymer wt % were varied to optimize hydrogel sensitivity to 1 mg/mL glucose at 37 0C, which correspond to normoglycemia. Glucagon release was tested over 48 hours in which the hydrogel released up to 80% of the payload, 40% more than its control. Rheological measurements demonstrate the shear-thinning property of the hydrogel. Finally, viscosity measurements in conjunction with injectability calculations show that the hydrogel can be formulated as an injectable. Chapter 4 describes the exploration of a degradable zwitterionic polymer as a PEG-alternative. Zwitterionic polymers have gained rising interest for their ability to stabilize proteins, increase circulation time, and retain bioactivity. While polyethylene glycol (PEG) still exists as the gold standard polymer used to mitigate challenges associated with native proteins, there are merits to investigating alternative polymers for this purpose. In this work, we report the site-selective conjugation of degradable zwitterionic poly(caprolactone-carboxybetaine) (pCLZ) to growth hormone receptor antagonist (GHA) B2036-alkyne and study bioactivity, pharmacokinetics, and immunogenicity. Azide-containing pCLZs of 5, 20, and 60 kDa are conjugated to GHA B2036-Alkyne via copper-catalyzed click reaction and their in vitro bioactivity is compared to PEGylated GHA B2036 5, 10, and 20 kDa, of matching hydrodynamic radii. The ability of pCLZs to elicit IgG and IgM antibody production was tested in vivo and no measurable antibody production was detected. Herein, we report that pCLZs demonstrate a high retention of bioactivity, as measured by half-maximal inhibitory concentrations in vitro, as well as low immunogenicity in vivo. Using 18F labeled PET/CT imaging, pharmacokinetics of our pCLZ conjugates show a significant increase in circulation time by 23 min compared to that of GHA B2036. Finally, in chapter five, a series of uniform, stereospecific protein-polymer conjugates were synthesized through copper-mediated click chemistry. Discrete, uniform polymers were provided by Wencong Wang from Prof. Jeremiah Johnson's lab at the Massachusetts Institute of Technology. The impact of molecular features of the conjugated polymers were evaluated through activity studies of growth hormone antagonist. Preliminary attempts at crystallizing the protein, polymer, and protein-polymer conjugates are demonstrated. Crystallization screening and crystallography model fitting was done largely with help from Genesis Falcon, Niko Vlahakis, and Dr. Michael Sawaya.

Applications of Polymers in Drug Delivery, Second Edition, provides a comprehensive resource for anyone looking to understand how polymeric materials can be applied to current, new, and emerging drug delivery applications. Polymers play a crucial role in modulating drug delivery and have been fundamental in the successful development of many novel drug delivery systems. This book describes the development of polymeric systems, ranging from conventional dosage forms to the most recent smart systems. Regulatory and intellectual property aspects as well as the clinical applicability of polymeric drug delivery systems are also discussed. The chapters are organized by specific delivery route, offering methodical and detailed coverage throughout. This second edition has been thoroughly revised to include the latest developments in the field. This is an essential book for researchers, scientists, and advanced students, in polymer science, drug delivery, pharmacology/pharmaceuticals, materials science, tissue engineering, nanomedicine, chemistry, and biology. In industry, this book supports scientists, R&D, and other professionals, working on polymers for drug delivery applications. Explains how polymers can be prepared and utilized for all major drug delivery routes Presents the latest advances, including drug targeting, polymeric micelles and polymersomes, and the delivery of biologicals and nucleic acid therapeutics Includes appendices with in-depth information on pharmaceutical properties of polymers and regulatory aspects

Polymeric materials are now playing an increasingly important role in pharmaceuticals, as well as in sensing devices, in situ prostheses and probes, and microparticle diagnostic agents. This new volume consists of twenty-two recent research-based reports on the developments in these areas of pharmaceutical and biomaterials technology. The reports w

Emphasizing four major classes of polymers for drug delivery-water-soluble polymers, hydrogels, biodegradable polymers, and polymer assemblies-this reference surveys efforts to adapt, modify, and tailor polymers for challenging molecules such as poorly water-soluble compounds, peptides/proteins, and plasmid DNA.

Proteins and peptides have become an important class of therapeutics due to their high specificity and general biocompatibility. However, using proteins and peptides as drugs has several intrinsic challenges. These macromolecules are generally cleared rapidly due to renal filtration and enzymatic degradation following administration. Issues of instability during storage due to their chemical composition and specific three-dimensional confirmations necessitate that most protein and peptide therapeutics be stored in the refrigerator or as a lyophilized powder. Additionally, they must be administered through injection and are not responsive to intrinsic biological signals, unlike endogenous processes. Thus, it is important to develop methods to improve characteristics of protein and peptide therapeutics to improve their stability, pharmacokinetics, and delivery in response to biological stimuli. Chapter Two describes the investigation of the insulin stabilization properties of trehalose glycopolymer as excipient and conjugate. Addition of a styrenyl backbone trehalose polymer excipient stabilized insulin against aggregation induced by exposure of insulin to heat or mechanical agitation. Conjugation of the trehalose polymer to insulin was achieved by reductive amination and the stability assays were repeated with the conjugate, showing results like the excipient. The conjugation site was identified as GlyA1 and LysB29 by indirect characterization through acid-cleavage of the polymer. While conjugation prolonged the half-life in mice, addition of trehalose polymer excipient did not alter protein pharmacokinetics. The mechanism of insulin stabilization was investigated with a methacrylate backbone trehalose polymer excipient, showing presence of the polymer inhibits both fibrillation and deamidation. Chapter Three continues the development of a new strategy for site-specific conjugation of a trehalose polymer to insulin for improved stability and bioactivity. Conditions for AGET ATRP under mild, aqueous conditions were optimized. A site-specific insulin macroinitiator was prepared targeting modification at LysB29 utilizing its higher nucleophilicity over the other possible amine conjugation sites and purifying to isolate the desired species. Trehalose monomer was polymerized directly from this site-specific macroinitiator resulting in a conjugate with improved heat stability. A lower dosage of the site-specific conjugate compared to the nonspecific conjugate was needed to achieve the same change in blood glucose. Chapter Four details the synthesis of blood triggered self-immolative linkers designed for use as spacers for rapid-acting insulin-trehalose glycopolymer conjugates. Linkers triggered by serum albumin through base-catalyzed -elimination were first prepared and triggering was characterized. During conjugation, the first linker underwent premature triggering from the primary amines of insulin and the exposed amine catalyzed further triggering. The second linker design underwent base-catalyzed self-immolation over the course of 20 h. Linkers that could be triggered by the thiol concentration in the blood were then synthesized and evaluated. Both aliphatic and aromatic linkers underwent rapid self-immolation with small molecules across the disulfide under relevant glutathione concentrations. Conjugation with trehalose glycopolymer slowed the kinetics of the self-immolation, likely because of the increase in steric bulk. Chapter Five describes optimization of the background release of insulin from a trehalose glycopolymer hydrogel for improved stability and glucose-responsive delivery of the protein. Several strategies were used to decrease the background release. Two methods to increase the binding affinity of the boronic acid to polyols was used to strengthen the hydrogel network. The influence of pore size/crosslink density was also explored. Finally, incorporation of comonomers for electrostatic attraction to insulin resulted in the lowest background release of insulin without glucose after optimization of gelation procedure. Chapter Six introduces glucose-responsive materials for regulation of glucagon delivery. Glucose-responsive nanogels are prepared by precipitation polymerization and post-polymerization modification with phenylboronic acid as glucose-sensing unit. Nanogels were thermo- and glucose-responsive through incorporation of thermoresponsive pNIPAM or pPEGMA with glucose acting as an additive that alters the hydration of the polymers. Native glucagon was found to degrade during the loading of the nanogels, so a more stable soluble analog was used that improved to loading.

Polymers have played a critical role in the rational design and application of drug delivery systems that increase the efficacy and reduce the toxicity of new and conventional therapeutics. Beginning with an introduction to the fundamentals of drug delivery, Engineering Polymer Systems for Improved Drug Delivery explores traditional drug delivery techniques as well as emerging advanced drug delivery techniques. By reviewing many types of polymeric drug delivery systems, and including key points, worked examples and homework problems, this book will serve as a guide to for specialists and non-specialists as well as a graduate level text for drug delivery courses.

Annotation The review focuses on the use of pharmaceutical polymer for controlled drug delivery applications. Examples of pharmaceutical polymers and the principles of controlled drug delivery are outlined and applications of polymers for controlled drug delivery are described. The field of controlled drug delivery is vast therefore this review aims to provide an overview of the applications of pharmaceutical polymers. The review is accompanied by approximately 250 abstracts taken from papers and books in the Rapra Polymer Library database, to facilitate further reading on this subject.