Synthesis and characterization of antimicrobial polylactide via ring‐opening polymerization and click chemistry methods

Abstract

Novel biodegradable polylactide (PLA) copolymers bearing pendant antimicrobial agent groups were successfully fabricated with a combination of ring‐opening copolymerization and copper(I)‐catalysed azide–alkyne cycloaddition click reaction in a two‐step reaction procedure. First, biodegradable PLA copolymers bearing azido groups were synthesized by the ring‐opening copolymerization of l‐lactide and 2,2‐ bis(azidomethyl)trimethylene carbonate in the presence of 1‐dodecanol as protic co‐initiator and tin(II) 2‐ethylhexanoate (Sn(Oct)2) as the catalyst. Then, alkyne functionalized quaternary ammonium salts were attached onto the azido groups of the copolymers via a Huisgen 1,3‐dipolar cycloaddition reaction to give PLA imparting antimicrobial activity. The chemical structure and composition of the copolymers were clearly confirmed using 1H NMR and Fourier transform infrared spectroscopies and gel permeation chromatography. Thermal phase transition temperatures (Tm and Tg) and the thermal stability of the polymers were investigated by DSC and TGA experiments, respectively. The antimicrobial activity tests were carried out against Gram‐negative (Escherichia coli) and Gram‐positive (Staphylococcus aureus) bacteria by the drop plate method. It was observed that antimicrobial agents are more active in the polymeric form than in the monomeric form. Also, the activity depends on the compositional ratio and the length of the alkyl group on the ammonium salts. © 2018 Society of Chemical Industry

Azide-Substituted Polylactide: A Biodegradable Substrate for Antimicrobial Materials via Click Chemistry Attachment of Quaternary Ammonium Groups

“…Thus, the covalent attachment of an antimicrobial agent to the polymer might prove to be advantageous in extending the bactericidal activity . Several reports of covalently modified polycationic PL analogues have appeared, involving the surface modification of PL films, − modification at the chain ends, − or the preparation of ammonium-substituted poly­(lactide- co -carbonate) co-polymer . In contrast, we demonstrate an efficient strategy to incorporate quaternary ammonium groups along the backbone of PL and consequently throughout the bulk of the material using CuAAC coupling chemistry.…”

“…58 Several reports of covalently modified polycationic PL analogues have appeared, involving the surface modification of PL films, 59−61 modification at the chain ends, 62−64 or the preparation of ammonium-substituted poly(lactide-co-carbonate) co-polymer. 65 In contrast, we demonstrate an efficient strategy to incorporate quaternary ammonium groups along the backbone of PL and consequently throughout the bulk of the material using CuAAC coupling chemistry. Such antimicrobial materials could be used to form coatings to maintain a sterile environment or to design bacterio-resistant biomedical devices.…”

Synthesis, characterization and chemical sensor applications of pyrene side‐functional polylactide copolymers

“…So, the melting temperature ( T m ) in the determined temperature range due to the semicrystalline PLA shifting towards an amorphous structure cannot be seen in Fig. S6 48 …”

From Antibacterial to Antibiofilm Targeting: An Emerging Paradigm Shift in the Development of Quaternary Ammonium Compounds (QACs)

“…In addition, the literature describes examples of obtaining QA-functionalized surfaces/materials using ring-opening polymerization 231 and click chemistry methods. 232,233 While the antimicrobial activity of QACs in solution has been studied extensively, surface covalent binding and limited diffusion can lead to a change in the biocidal mechanism of action. 38 Polymer brushes were grafted onto glass and silicon substrates to determine the effect of alkyl chain length on the biocidal activity of immobilized QACs.…”