Thermoresponsive Poly(N-Isopropylacrylamide-co-Dimethylaminoethyl Methacrylate) Microgel Aqueous Dispersions with Potential Antimicrobial Properties

Abstract

The work herein describes the preparation of thermoresponsive microgels with potential antimicrobial properties. Most of the work performed so far regarding microgels with antimicrobial activity, deals with the ability of microgels to carry and release antibiotics or antimicrobial agents (antimicrobial peptides). The originality of this work lies in the possibility of developing intrinsic antimicrobial microgels by copolymerization of the well-known thermoresponsive monomer, N-isopropylacrylamide (NIPAM) with dimethylaminoethyl methacrylate (DMAEMA), a water-soluble monomer, to form microgels via precipitation polymerization (radical polymerization). Due to the presence of a tertiary amine in the DMAEMA comonomer, microgels can be modified by N-alkylation reaction with methyl and butyl iodide. This quaternization confers positive charges to the microgel surfaces and thus the potential antimicrobial activity. The effect of DMAEMA content and its quaternization with both, methyl and butyl iodide is evaluated in terms of thermal and surface charge properties, as well as in the microgel size and viscoelastic behavior. Finally, a preliminary study of the antimicrobial activity against different microorganisms is also performed in terms of minimum inhibitory concentration (MIC). From this study we determined that in contrast with butylated microgels, methylated ones show potential antimicrobial activity and good physical properties besides of maintaining microgel thermo-responsiveness.

Synthesis of Temperature and Light Sensitive Copolymers with Controlled Aggregation during Phase Transitions

“…Moreover, the temperature span of the phase transition becomes significantly smaller as the concentration of PEP increased. This result is in good agreement with reported studies on poly( N ‐ethylacrylamide) and poly( N ‐isopropylacrylamide) . Furthermore, the LCST can also be obtained by extrapolation of the curves of LCSTs for different polymer concentrations.…”

An improved method in fabrication of smart dual-responsive nanogels for controlled release of doxorubicin and curcumin in HT-29 colon cancer cells

“…Two additional peaks around 1649 cm −1 , 1549 cm −1 were corresponding to the stretching vibration of C = O groups in amide functional groups and N-H bending vibration of amide groups in NIPAAm, respectively. The broad peak around 3451 cm −1 referred to the N-H stretching vibration of NIPAAm amide groups [47,48].…”

A Way to Predict Gold Nanoparticles/Polymer Hybrid Microgel Agglomeration Based on Rheological Studies

“…They studied their fractal structure and concluded that both salt concentration and temperature modify the interactions among microgels [8,43]. Recently, we also attempt to modify microgels colloidal behavior through quaternization but no relevant differences were obtained [44]. Therefore, to determine the flow behavior of the hybrid microgel dispersions and to understand how hybrid microgels interact within the aqueous dispersion could be as relevant as the characterization of their responsiveness.…”

“…These two scaling theories, which are an extension of the computer model proposed by Brown and Ball [45] are based on the fact that microgel dispersions are a collection of flocs–fractal objects closely packed throughout the sample-. These models were recently used to study the interactions occurring among poly(N-Isopropylacrylamide) polycationic microgels [44].…”