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Click Cu(I)-catalyzed polymerization of diynes and diazides was performed to obtain a novel type of linear copolymer, which were prepared from monomers derived from poly (ethylene glycol), 5, 5′-azodisalicylic acid [olsalazine] and 1,4-butanediol diglycidyl ether. The resulting copolymers will carry ester and azo functions along the polymer backbone, so they will be sensitive to pH as well as be degraded by azoreductase enzymes present in the colonic microbiota. Most of the copoly (azoester triazole)s obtained were water soluble, and all of them were characterized by Fourier transform infrared, nuclear magnetic resonance (NMR), and gel permeation chromatography (GPC). Differential scanning calorimetry (DSC) revealed them to be amorphous, and in general, the polymers were stable up to 250 °C under nitrogen as demonstrated by thermogravimetric analysis (TGA). The degradation behavior of the polymers was evaluated in vitro. Degradation studies were carried out at 37 °C in buffered salt solution at pH 7.4, and were monitored by GPC and NMR spectroscopies. A biodegradation experiment of a water-soluble prototype polymer showed that they are biodegradable via a strain of Enterococcus faecalis. The experiment was monitored using ultraviolet–visible spectroscopy.

Novel linear cationic poly(amide aminotriazole)s (PATnD) with secondary amine groups in the backbone were obtained by using azide-alkyne 1,3-dipolar cycloaddition reactions: metal- and solvent-free (thermal conditions, PATTnD) or copper(I)-catalyzed (Sharpless conditions, PATCnD). PATnD were investigated in vitro against strains of E. coli, P. aeruginosa, S. aureus, and S. epidermidis. Hemolytic activity was tested using human red blood cells (hRBC), and very low or no hemolytic activity was observed. The cytotoxicity of PATnD polymers against Human Gingival Fibroblasts (HGnF) cells was concentration-dependent, and significant differences between PATT1D and PATC1D were observed. The ability of these polymers to induce resistance against both Gram-positive and Gram-negative bacteria was also assessed. Studied bacterial strains acquired resistance to catalytic polymers (PATCnD) in initial passages meanwhile resistance to thermal polymers (PATTnD) appears in later passages, being the increase of the minimum inhibitory concentration lower than in catalytic polymers. This result, together with the higher biocidal capacity of thermal polymers compared to catalytic ones, seems to suggest an influence of the regiospecificity of the polymers on their antibacterial characteristics. This study also demonstrates that PAT1D polymers, which do not appear to have strong hydrophobic residues, can exert significant antimicrobial activity against Gram-positive bacteria such as S. epidermidis. This pair of polymers, PATC1D and PATT1D, displays the greatest antimicrobial activity while not causing significant hemolysis along with the lowest susceptibility for resistance development of the polymers evaluated.

We describe the synthesis and characterization of four new light and reduction sensitives poly(azoamide triazole)s, in which the azobenzene units are found along the main chain of the macromolecule. These polymers were prepared by the azide-alkyne cycloaddition reaction catalyzed with copper (I) (CuAAC). They were obtained in high yield and with apparent molecular weights in the range from 95 to 148 kDa. All poly(azoamide triazole)s are soluble in polar aprotic solvents, and two of them are also soluble in chloroform showing good coating and film-forming properties. They were characterized by Fourier transform infrared, nuclear magnetic resonance (NMR), ultraviolet-visible spectroscopy and gel permeation chromatography (GPC). The photoisomerization study of the synthesized polymers has been carried out by UV–Vis spectroscopy, as well as their trans-cis-trans reversibility behavior. Differential scanning calorimetry (DSC) and themogravimetric analysis (TGA) were used to investigate their thermal properties. Results show that the polymers were amorphous and stable up to 300 °C under nitrogen. The hydrolytic degradation of films of these polymers has been studied in vitro under various conditions of pH and temperature and was monitored by GPC. Furthermore, the presence of azo units along the polymer backbone as cleavable groups provides access to their degradation by reduction. In this sense, the degradation of polymers has also been studied using sodium dithionite as a mimic of the enzyme azoreductase. The results of these studies show that the polymers are stable enough under hydrolytic physiological conditions, but they degrade rapidly when sodium dithionite is used. A preliminary study of biocompatibility of polymers PAAT1 and PAAT4 has been carried out. A hemolysis study with human red blood cells (hRBC) and a cytotoxicity study with human gingival fibroblasts (HGnF) have been carried out. The results obtained suggest that these polymers could be good candidates to be used as drug coating materials. Ministerio de Economía y Competitividad MAT2016-77345-C3-2-P Universidad de Sevilla VI Plan Propio, PP2021/00000658