| dc.description.abstract | Due to their potential in a number of bio-medical applications, including tissue repair and regeneration, drug administration, antimicrobial and antifouling applications, biomimetic catechol-functionalized hydrogels have received a lot of interest.
Dopamine was developed as a photo-initiator in chapter II to create functional catecholamine hydrogels utilizing a one-pot method. Dopamine produces free radicals under UV irradiation in an acidic solution, most likely semiquinone radicals, to initiate the addition polymerization, according to pseudo first-order kinetics. Dopamine-initiated photopolymerization offers a simple and straightforward method while also preventing the unfavorable oxidation to catechol groups. For the creation of biocompatible hydrogels, superhydrophilic sulfobetaine methacrylate (SBMA) was used. In order to investigate the polymerization mechanism and the ideal experimental circumstances in terms of pH, UV dosages, and dopamine concentration, 1H nuclear magnetic resonance, UV-vis spectroscopy, gel permeation chromatography, and rheological tests were carried out. The increased mechanical characteristics, self-healing and injectability, high adhesiveness, and fouling resistance of the resulting catechol-functionalized pSBMA hydrogels were evidence of their special qualities. As a result, the synthetic approach to creating catecholamine hydrogels can benefit the utilization of dopamine in a number of applications.
The study′s goal in chapter III is to create a modification technique that will make consistent catechol-assisted zwitterionization on nitinol alloy possible for biocompatibility and fouling resistance. Dopamine-initiated photo-polymerization is used to create catechol-functionalized polysulfobetaine methacrylate (pSBMA/DA). Semiquinone radicals produced from dopamine (DA) under UV irradiation inhibited pH 2 solution intramolecular cyclization and intermolecular dimerization from losing an electron. It is revealed how pseudo-first-order polymerization kinetics and relationships between the number average molecular weight and apparent rate constant in photopolymerization for pSBMA/DA. PSBMA/DA starts to aggregate in a solution with a pH of 3, preventing catechol moieties from early oxidation and enabling even deposition on the nitinol substrate. Catechol moieties are triggered to interact with the nitinol surface via the creation of bidentate binding as pSBMA/DA extends after pH adjustment to 8.5. A shorter pSBMA/DA chain with a higher catechol content offers more anchoring sites to improve the coverage of zwitterionic moieties on substrates, according to X-ray photoelectron spectroscopy (XPS) study. Interesting, pH-transition method-based pSBMA/DA deposition was seen in atomic force microscopy (AFM) pictures to be homogeneous and smooth. Strong ionic hydration of the pSBMA/DA coating on the surface of nitinol prevents non-specific bio-foulant adsorption and allows for outstanding antifouling capabilities. Nitinol treated with zwitterion has a 99.9% decrease rate for Staphylococcus aureus and Escherichia coli adhesion. Additionally, after 24 hours of incubation, pSBMA/DA displays a strong antifouling performance against NIH 3T3 mouse fibroblasts in culture conditions. All things considered, the pSBMA/DA coating via pH transition technique offers a promising method for facilitating homogeneous surface functionalization for antifouling and coating technology. In chapter IV, it is discussed how biofoulants can stick to various surfaces and impair the functionality of industrial facilities, medical devices, and/or hospitals by spreading nosocomial infections. Surface immobilization of zwitterionic compounds can stop the foulants′ initial adhesion, but it is not widely used. In this research, we provide a simple, universal two-step surface modification method to increase fouling resistance. To create a ＂primer＂ layer (PDA/PEI), the substrates were submerged in a co-deposition solution containing dopamine and branching polyethyleneimine (PEI) in the first phase. The primary, secondary, and tertiary amine moieties of PEI were betainized by 1,3-propane sultone in the second step, resulting in zwitterions on substrates. Following betainization, the wettability of PS-grafted PDA/PEI (PDA/PEI/S) with ring-opening alkylation reaction changed. Surfaces made of PDA/PEI/S were found to have zwitterionic moieties according to X-ray photoelectron spectroscopy spectra. The relationship between PEI content, film thickness, primer stability, and betainization was further examined using ellipsometry and atomic force microscopy. Zwitterion-decorated substrates created under ideal conditions can display great resistance against bacterial fouling, attaining a 98.5% reduction in bacterial adhesion. The technique also demonstrates a substrate-independent property, permitting successful application on both organic and inorganic surfaces. Last but not least, the recently discovered method exhibits outstanding biocompatibility, showing no discernible difference from blank control samples. Overall, we believe that the simple surface modification technique will help advance the production of materials ornamented with zwitterion in the future.
In chapter V, application-oriented research on mussel-inspired material will be discussed. P(MPC-co-DMA) copolymers, composed of phosphobetaine MPC monomer and catechol DMA monomer, were investigated as a potential topical treatment for dry eye disease (DED). The copolymers were synthesized via random free-radical copolymerization, producing different degrees of DMA functionalization. Owing to the catechol residues, the copolymers exhibited mucoadhesive properties, inducing a red shift in mucin absorbance maxima (UV-VIS) and an increase in adsorbed mass density on the mucin-deposited surface. Interestingly, p(MPC-co-DMA) facilitated robust adhesion on the ocular surface of the rabbit eye after 4 days of topical instillation. For pharmacological effect, the copolymers demonstrated excellent anti-oxidant and anti-inflammatory, scavenging intracellular reactive oxygen species (ROS) and inhibiting inflammatory factor expression and cell apoptosis. As a result, DED-induced rabbit eyes exhibited enhanced tear film stability and lacrimal fluid secretion, suggesting signs of recovery. For future perspective, p(MPC-co-DMA) can be further post-modify with active reagents (such as antibodies, antibiotics) for enhancing their antibacterial activity or use as a drug carrier. | en_US |