Theoretical Study of Vinyl-Sulfonate Monomers and Their Effect as the Dopants of Polyaniline Dimers.

Establishing the structure-property relationships of monomers and polymers via theoretical chemistry is vital for designing new polymer structures with a specific application. Developing bifunctional monomers with selective polymerizable sites is one of the strategies employed to obtain complex polymeric systems. In this work, a theoretical study on anilinium 2-acrylamide-2-methyl-1-propanesulfonate (ani-AMPS) and anilinium 4-styrenesulfonate (ani-SS) monomers and their respective doped polyaniline dimer (PAni-d AMPS or PAni-d SS) was performed. The study focused on understanding the susceptibility of the vinyl group to a radical attack and the conformation changes resulting from the coordinated covalent bond between sulfonate and aniliniun. Applying Density Functional Theory with the B3LYP functional and a basis set of 6 - 31 + G(d,p), the structures of the ani-AMPS, ani-SS, PAni-d AMPS, and PAni-d SS were optimized, and the different chemical descriptors were determined. The simulation showed that the reactivity of the vinyl group in the ani-AMPS is slightly higher. The sulfonate group undergoes a conformational change when bonding with PAni-d AMPS or PAni-d SS compared to its respective bifunctional monomer. Additionally, the electronegativity of PAni-d depends on the dopant's structure. Thus, the bonded spacer between the vinyl and sulfonate groups (dopant) plays a notable role in the final characteristics of ani-AMPS, ani-SS, PAni-d AMPS, and PAni-d SS.

RGD Peptide-Functionalized Polyether Ether Ketone Surface Improves Biocompatibility and Cell Response.

Polyether ether ketone (PEEK) is a biocompatible polymer used in maxillofacial and orthopedic applications because of its mechanical properties and chemical stability. However, this biomaterial is inert and requires surface modification to make it bioactive, enhancing implant-tissue integration and giving the material the ability to interact with the surrounding microenvironment. In this paper, surface of PEEK was activated by oxygen plasma treatment and this resulted in increasing reactivity and surface hydrophilicity. Then, a polydopamine (PDA) coating was deposited over the surface followed by biofunctionalization with an RGD peptide. The plasma effect was studied by contact angle measurements and scanning electron microscopy. X-ray photoelectron spectroscopy confirmed the presence of PDA coating and RGD peptide. Crystallinity and phase identification were carried out through X-ray diffraction. Quantification of the immobilized peptide over the PEEK surface was reached through UV-vis spectroscopy. In addition, in vitro tests with fibroblast cell line (NIH/3T3) determined the viability, attachment, spreading, and proliferation of these cells over the modified PEEK surfaces. According to the results, PEEK surfaces functionalized with peptides demonstrated an increased cellular response with each successive surface modification.