Polymer brush-modified photopolymer network surfaces and their applications

Because of their important role in many areas of science and technology, polymer brushes have been extensively studied theoretically and experimentally. In the first part of my thesis, in order to understand the molecular weight behavior of polymer brushes, a new method to cleave polymer brushes were investigated. A new inimer (having both an initiator and monomer fragment) was synthesized. After growing polymer brushes from these inimers containing cleavable linkages, the polymer brush layers were characterized by various techniques. The brush chains were cleaved and collected, providing an opportunity to study and compare polymer grown in solution vs. polymer grafted from the inimer-inbedded surfaces. Molecular weight differences were determined since it has been assumed, but not confirmed, that polymers synthesized in both manners should have the same molecular weight. Since growing a brush layer from a photopolymer (PP) layer is different than growing brushes from the surface directly, the first part of my thesis is dedicated to showing the differences between these two surfaces and how the PP network affects the brush growth with using different characterization methods such as neutron reflectivity and secondary ion mass spectroscopy. These studies helped to understand the characteristic behavior of the polymer brushes such as where the initiation occurs, how the inimer concentration affects on the photopolymer properties. The next part of my thesis is about the possible applications of polymer brushes. We examined the antibacterial effects of –onium salts and enzymes attached to polymer brushes. It is already known that -onium salts can be used as antibacterial agents in solution. They can kill both Gram-positive and Gram-negative bacteria. In our case, polymer brushes were grown from the PP layer spin-coated on glass substrates, and we investigated their antibacterial effectiveness of these polymer brushes. Phosphonium salts and lysozyme were used as antibacterial agents. Lysozyme was chosen since it is biocompatible and can be used inside the body. Lastly, azobenzene-containing photoresposive polymer brushes were prepared and the surface properties before and after UV exposure were observed. The surface wettability changes dramatically, and using only UV light is one of the safest and cleanest way to alter surface properties

Photoresponsive Polymers Containing Nitrobenzyl Esters via Ring-Opening Metathesis Polymerization

This paper describes controlled ring-opening metathesis polymerizations (ROMP) of norbornene derivatives that bear photoreactive <i>o</i>-nitrobenzyl ester (NBE) moieties. Termination reactions have frustrated previous reported attempts to execute controlled radical polymerizations with nitrobenzyl ester-containing acrylate derivatives. We therefore prepared new NBE-containing norbornene derivatives, and found that polymerization with Grubbs’s ruthenium carbene catalysts led to complete consumption of monomer in minutes to hours and yielded polymers with predictable molecular weights. We also demonstrate the preparation of NBE-containing block copolymers and show through UV irradiation of these polymers in solution and in thin film that the NBE moieties remain photoreactive

Gene expression of pro-opiomelanocortin and melanocortin receptors is regulated in the hypothalamus and mesocorticolimbic system following nicotine administration

WOS: 000392790300013PubMed ID: 27890744Pro-opiomelanocortin (POMC)-derived peptides and their receptors have been shown to play important roles in natural and drug-induced reward and reinforcement. Reward process may involve the regulation of POMC gene expression and the gene expression of POMC-derived peptide receptors. The present study investigated the alterations observed in the transcript levels of POMC, melanocortin 3 (MC3R), melanocortin 4 (MC4R) and mu-opioid receptors (MOR) in the hypothalamus and mesocorticolimbic system during nicotine exposure. Rats were injected subcutaneously for 5 days with one of the three doses (0.2, 0.4 or 0.6 mg/kg/day, free base) of nicotine and were decapitated one hour after a challenge dose on the sixth day. mRNA levels of POMC in the hypothalamus, MC3R in the ventral tegmental area (VTA), MC4R and MOR in the medial prefrontal cortex (mPFC), nucleus accumbens, dorsal striatum, amygdala, lateral hypothalamic area and VTA were measured by quantitative real-time PCR. Our results showed that treatment with 0.6 mg/kg/day nicotine upregulated POMC mRNA in the hypothalamus and MC4R mRNA in the mPFC. Additionally, all three nicotine doses increased MC3R mRNA expression in the VTA. On the other hand, none of the nicotine doses altered MOR mRNA levels in the mesocorticolimbic system and associated limbic structures. These results suggest that nicotine may enhance melanocortin signaling in the mesocorticolimbic system and this alteration may be an important mechanism mediating nicotine reward. (C). 2016 Elsevier Ireland Ltd. All rights reserved.Ege University Scientific Research Projects CommissionEge University [2015-BAUM-002]This work was supported financially by Ege University Scientific Research Projects Commission (Research Fund Grant 2015-BAUM-002). The funding source had no involvement in study design; in the collection, analysis and interpretation of data; in the writing of the report; and in the decision to submit the article for publication

Wavelength-Selective Disruption and Triggered Release with Photolabile Polyelectrolyte Multilayers

This paper describes photosensitive polyelectrolyte multilayers (PEMs), constructed using layer-by-layer (LbL) self-assembly, which contain polymers that comprise combinations of photocleavable methacrylate esters and photoinert cationic methacrylate esters. The solubility of these polymers in aqueous base depends upon irradiation with either ultraviolet or visible light. PEMs with dialkylaminocoumarin groups dissolve upon irradiation with visible light, while analogous films with nitrobenzyl ester-substituted polymers dissolve upon irradiation with UV light. Wavelength-selective release of fluorescent polymers as guests is demonstrated using this approach