Synthesis and applications of protein/peptide-polymer conjugates

Recent advances in synthetic methodologies have brought us closer than ever to the precision conferred by nature. For example, the control possible in reversible deactivation radical polymerization enables us to design and synthesize macromolecules with unprecedented control over not only the polymer chain ends, but also the side chain functionality. Furthermore, this functionality can be exploited to afford chemical modification of peptides and proteins, with ever-improving site-specificity, yielding a range of well-defined protein/peptide-hybrid materials. Such materials benefit from the amalgamation of the properties of proteins/peptides with those of the synthetic (macro)molecules in question. Here, the latest developments in the synthesis of functional polymers and their use for preparation of well-defined protein/peptide-polymer conjugates will be discussed, with particular attention focused on modulating the stability, efficacy and/or administration of therapeutic peptides

Direct peptide bioconjugation/PEGylation at tyrosine with linear and branched polymeric diazonium salts

Direct polymer conjugation at peptide tyrosine residues is described. In this study Tyr residues of both leucine enkephalin and salmon calcitonin (sCT) were targeted using appropriate diazonium salt-terminated linear monomethoxy poly(ethylene glycol)s (mPEGs) and poly(mPEG) methacrylate prepared by atom transfer radical polymerization. Judicious choice of the reaction conditions-pH, stoichiometry, and chemical structure of diazonium salt-led to a high degree of site-specificity in the conjugation reaction, even in the presence of competitive peptide amino acid targets such as histidine, lysines, and N-terminal amine. In vitro studies showed that conjugation of mPEG 2000 to sCT did not affect the peptide's ability to increase intracellular cAMP induced in T47D human breast cancer cells bearing sCT receptors. Preliminary in vivo investigation showed preserved ability to reduce [Ca 2+] plasma levels by mPEG 2000-sCT conjugate in rat animal models. © 2012 American Chemical Society

Characterisation studies of novel block copolymer assemblies

In the last decade, block copolymers have attracted growing interest because of their ability to form a wide range of nanostructures through self assembly. These nanostructures could be designed to have miscellaneous properties, such as high stability, biocompatibility, functionality, capacity of carrying a variety of molecules and versatile architectures. Block copolymers can be prepared as hybrid systems with many diverse compounds including biomolecules. Moreover, they can be environment responsive, and release of components within the polymer can be controlled by stimuli. Due to these properties, block copolymers are finding applications in several areas including drug delivery, biotechnology and diagnostics. In this thesis it was aimed to characterise a variety of novel block copolymer assemblies in order to have a better understanding about the properties of these materials for potential applications in pharmaceutical SCIences. Assemblies including the block co-polymers of synthetic materials, the block co-polymers of synthetic materials and proteins, and the block co-polymers of synthetic materials and nucleic acids were characterised by AFM, and additionally by TEM, DLS, fluorescence spectrometry and zeta potential measurements. The morphologies and self-assembly mechanisms of the structures were investigated by altering the conditions (i.e. temperature, pH and buffer strength), and the real-time responses were recorded in order to be able to VI Abstract predict in vitro and in vivo behaviours of these systems. Also the effects of additional substances (i.e. biomolecules and reducing agents) to assembly/disassembly paths of the materials were inspected. The results of this project provide some useful and new insights about the behaviour of a range of block copolymer materials such as self-assembly properties of the synthetic block copolymer structures and the stability of these assemblies at various pH values, dynamic nature of protein-polymer conjugates across temperature changes, and response mechanisms of DNA-polymer conjugates across a number of stimuli (i.e. binding / hybridisation / strand breaking stimulus) which influence the assembly/disassembly paths of the materials. This information leads to better understanding of their potential applications as drug delivery systems, advanced responsive therapeutics, and diagnostics, and also designing better systems in future studies. VBEThOS - Electronic Theses Online ServiceGBUnited Kingdo

The interactions of human ovarian cancer cells and nanotextured surfaces: Cell attachment, viability and apoptosis studies

This journal is © The Royal Society of Chemistry.Understanding cell responses to the topography they are interacting with has a key role in designing surfaces due to the distinctiveness in the responses of different cell types. Thus far, a variety of surface textures have been fabricated, and the cellular responses of diversified cell lines to the surface textures have been assessed together with surface chemistry. However, the results reported in the literature are contradictory, and also not in-depth for inferring the relevance between cells, surface chemistry, and surface topography. Starting from this point of view, we focused on fabricating surfaces having extracellular matrix-like surface patterns and investigated the influence of patterning on human ovarian cancer cells. In this study, hemispherical protrusion-shaped, nanotextured surfaces were prepared via colloidal lithography and polymer casting methods using monolayer templates prepared from 280 nm, 210 nm, and 99 nm polystyrene particles and polydimethylsiloxane moulds. Then, the surface textures were transferred to biocompatible polycaprolactone films. After the characterisation of the surfaces via atomic force microscopy, X-ray photoelectron spectroscopy, and contact angle measurements, the cellular response to topography was evaluated by cell attachment, viability, and apoptosis studies. The results were compared with non-textured surfaces and control plate wells. The results showed that human ovarian cancer cell attachment increased with nanotexturing, which suggests that nanotexturing may be a promising approach for cancer cell modulation, and may have the potential to introduce new strategies for cancer treatment

Human Papilloma Virus Prevalence in Hyperplastic Tonsils and Adenoids in Children and Young Adults

Objective: Our aim was to determine HPV prevalence and genotypes in nontumoral tonsillar and/or adenoid tissue in young adults to open a discussion about the rationale of HPV detection in tonsil and adenoid tissues because of the cancer development risk. Material and Methods: Archived resection materials of 258 patients treated between 2003 and 2007 were retrieved for HPV detection and typing. Sections of formalin-fixed, paraffin-blocked tissue samples of each resected material were used as the DNA source. Six patients were excluded because of the inadequate quality of the extracted DNA. The age range of the remaining 252 patients was between 5 and 21 years (11.94 +/- 4.20). After PCR screening, four different sets of primers covering 18 HPV types were used for HPV genotyping by multiplex polymerase chain reaction (MPCR). Results: Sixteen of the 252 surgical samples, namely nine of 114 tonsillectomies (7.9%), four of 87 adenoidectomies (4.6%), and 3 of 51 adenotonsillectomy tissues (5.9%) were found to contain the HPV genome (6.3%). Genotypes revealed that HPV-16 was the dominant genotype, found in 11 cases, followed by HPV-6/11 in four cases, and HPV-31 in one case. Conclusion: The prevalence of HPV in children and young adults that suffered from upper airway obstruction due to nontumoral tonsil and/or adenoid overgrowth was found to be 6.3% in our study. This study reveals the need for further molecular assists for HPV under the light of 6.3% of detected HPV prevalence and the high risk HPV type 16 predominance. Since the oncogenic risk, we strongly suggest evaluation of HPV in tonsillectomy and adenoidectomy material similar to oropharyngeal squamous etithelium

Tissue adhesives: from research to clinical translation

Sutures, staples, clips, and skin closure strips are used as the gold standard to close wounds after an injury. In spite of being the present standard of care, the utilization of these conventional methods is precarious amid complicated and sensitive surgeries such as vascular anastomosis, ocular surgeries, nerve repair, or due to the high-risk components included. Tissue adhesives function as an interface to connect the surfaces of wound edges and prevent them from separation. They are fluid or semi-fluid mixtures that can be easily used to seal any wound of any morphology-uniform or irregular. As such, they provide alternatives to new and novel platforms for wound closure methods. In this review, we offer a background on the improvement of distinctive tissue adhesives focusing on the chemistry of some of these products that have been a commercial success from the clinical application perspective. This review is aimed to provide a guide toward the innovation of tissue bioadhesive materials and their associated biomedical applications