Effect of polyethylene glycol plasticizer on long‐term antibacterial activity and the release profile of bacteriocin nisin from polylactide blends

Abstract

This work describes the synergetic effect of polyethylene glycol (PEG) in polylactide (PLA) blends, wherein the polyether acts as both the plasticizer and functional additive, ensuring the long-term antimicrobial activity of bacteriocin nisin. Two types of PEG with the molecular weights of 1000 and 6000 g.mol −1 (20 wt.%) were used to plasticize the PLA blends. The aforementioned bacteriocin nisin, at concentrations ranging between 0.02 and 0.15 wt.% (8000-60 000 IU.g −1 ), was incorporated into the samples by the solvent cast technique. The effect of various PEG on the structural, mechanical, and thermal properties of the PLA-based blends were investigated by scanning electron microscopy, Fourier transform infrared spectroscopy, stressstrain analysis, differential scanning calorimetry, and dynamic mechanical analysis, respectively. The antibacterial activity of the samples was detected by the agar diffusion technique against Micrococcus luteus. Furthermore, the antibacterial properties of the samples were tested according the ISO 22196 standard against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus, Listeria monocytogenes) bacterial strains. The nisin was detected by high performance liquid chromatography, the device having been equipped with a UV/vis detector. The results show that the PEG, besides its plasticizing effect, significantly enhances the release profile and sustains long-term antibacterial activity of nisin in a PLA matrix.

Antibacterial Films Based on Polylactide with the Addition of Quercetin and Poly(Ethylene Glycol)

“…These observations are consistent with results obtained by other researches [ 50 , 51 ] in relation to similar composition. During the study it has been established that the decrease in tensile strength, as well in Young’s modulus values, can be attributed to poor stress transfer between the PLA and PEG phases [ 52 ]. An introduction of quercetin into polylactide-PEG systems significantly improves the properties indicated above.…”

Influence of Tea Tree Essential Oil and Poly(ethylene glycol) on Antibacterial and Physicochemical Properties of Polylactide-Based Films

“…This is related to the phase separation of the PLA-PEG mixture during chloroform evaporation and the formation of small aggregates of plasticizer inside the polylactide matrix [25]. SEM photographs of the plasticized materials, based on polylactide with the addition of TTO, reveal convexities associated with the presence of PEG, which does not uniformly blend with PLA [26]. Moreover, in the cases of samples consisting of PLA, PEG and TTO pores were not formed while the materials were being dried.…”

A feasible strategy to constructing hybrid conductive networks in PLA‐based composites modified by CNT‐d‐RGO particles and PEG for mechanical and electrical properties

“…It is well known that conductive polymer composites (CPCs) can achieve an superior chemical resistance, flexibility, good processability, and changeable conductivity with variation of conductive filler and be adopted as novel conductive materials. To solve these drawbacks and satisfy above requirement, blending with nanoscale particles is one of the commonly used strategy . Several researches have shown that the large aspect ratio and excellent strength of nanoparticles, such as CNTs, graphene nanoplates, and silver nanowire, can effectively improve the shortages in PLA to obtain good crystallization performance or unexpected properties of PLA‐based composites …”

“…To solve these drawbacks and satisfy above requirement, blending with nanoscale particles is one of the commonly used strategy. [9][10][11] Several researches have shown that the large aspect ratio and excellent strength of nanoparticles, such as CNTs, graphene nanoplates, and silver nanowire, can effectively improve the shortages in PLA to obtain good crystallization performance or unexpected properties of PLA-based composites. [10][11][12] Carbon nanotubes (CNTs) are typical fibrous materials with high aspect ratio, high thermal conductivity and conductivity, and environment friendliness that is used to achieve high crystallization rate, high modulus and volume conductivity for PLA-based composites.…”

“…Poly (lactic acid) (PLA), a nonpetroleum‐based completely biodegradable polymer material, is a typical polycondensation material of lactic acid . PLA features not only good biocompatibility, good biodegradability, high strength, and modulus but also good processability and thermal plasticity; thus, it has increasingly grown in terms of its properties exploration and a wide range of applications, such as traumatic wound surgery without sutures, drug delivery, and 3D printing materials . Unfortunately, PLA exhibits an intrinsic feature, that is, its asymmetrical structure of chains, which causes deficiency involving very low crystallinity and crystallization rate during melt processing, thus further leading to inferior thermostability and toughness problems during its long service life .…”