Polymer Library

Biocidal Polymers - March 2016

This month we're looking at polymers with biocidal properties. Products with antimicrobial/biocidal properties have been increasingly sought after over recent years; for many consumers the prospect of sanitising and improving hygiene is a high priority. As a result, the option of giving products an inherent ability to kill germs has obviously been very appealing to many manufacturers. This has been reflected in a steady increase in the levels of research in the area, although there is discussion of over-use of biocides, so it's very important that these chemicals are used selectively. However, in some areas, like the medical and food sectors, these properties are essential.

Biocidal properties can be achieved through selection of materials - they occur naturally in some polymers/co-polymers, or alternatively, materials can be enhanced with biocidal additives.

Why not read some of the latest literature in this area? There is a selection of abstracts from the Polymer Library looking at polymers with biocidal properties below.

Abstracts

These abstracts were highlighted in the March Newsletter and found in the Polymer Library.

Click on the 7-digit accession numbers to find out about ordering a copyright-cleared full text copy of the items shown.

1222256 - Multifunctional polyphenols- and catecholamines-based self-defensive films for health care applications
In an era of relentless evolution of antimicrobial resistance, there is an increasing demand for the development of efficient antimicrobial coatings or surfaces for food, biomedical, and industrial applications. This study reports the laccase-catalysed room-temperature synthesis of mechanically robust, thermally stable, broad spectrum antimicrobial films employing interfacial interactions between poly(vinyl alcohol), PVA, and 14 naturally occurring catecholamines and polyphenols. The oxidative products of catecholamines and polyphenols reinforce the PVA films and also alter their surface and bulk properties. Among the catecholamines-reinforced films, optimum surface and bulk properties can be achieved by the oxidative products of epinephrine. For polyphenols, structure-property correlation reveals an increase in surface roughness and elasticity of PVA films with increasing number of phenolic groups in the precursors. Interestingly, PVA films reinforced with oxidised/polymerised products of pyrogallol (PG) and epinephrine (EP) display potent antimicrobial activity against pathogenic Gram-positive and Gram-negative strains, whereas hydroquinone (HQ)-reinforced PVA films display excellent antimicrobial properties against Gram-positive bacteria only. We further demonstrate that HQ and PG films retain their antimicrobial efficacy after steam sterilisation. With an increasing trend of giving value to natural and renewable resources, our results have the potential as durable self-defensive antimicrobial surfaces/films for advanced healthcare and industrial applications.
ACS Applied Materials and Interfaces, 8, No.2, 20 Jan. 2016, p.1220-1232, ISSN: 1944-8244, eISSN: 1944-8252, DOI: 10.1021/acsami.5b09633
Chetna Dhand; Sriram Harini; Mayandi Venkatesh; Neeraj Dwivedi; Ng A; Shouping Liu; Navin Kumar Verma; Seeram Ramakrishna; Beuerman R W; Xian Jun Loh; Rajamani Lakshminarayanan

1224902 - Bacterial membranes are the target for antimicrobial polysiloxane-methacrylate copolymer (Open Access - Free PDF Available)
Antibacterial polysiloxane polymers with pending tert-butylamine groups are a novel class of compounds that are compatible with silicone elastomers, but their mechanism of action is not well understood. The research into their action mechanism was conducted on a polysiloxane copolymer grafted with tert-butylaminoethyl methacrylate and covalently attached fluorescein. Fluorometric measurements results suggest that the polymer forms a stable link with bacteria. The results of b-galactosidase enzyme assay with the use of ortho-nitrophenyl-bgalactoside as a substrate show that the polymer has a damaging effect on bacterial membranes. The scanning and transmission electron micrographs of Escherichia coli cells incubated with the polymer prove further that the polymer's site of action is bacterial cell membranes. In order to investigate the polymer interaction with bacterial membranes the fluorescein labelled polymer was incubated with bacterial cells and membranes isolation and identification method was next applied. The E. coli membrane fractions were identified by light scattering, protein content, oxidase NADH activity and N-phenylnaphtylamine fluorescence measurements, as well as electron microscopy. Oxidase NADH and N-phenylnaphtylamine were the inner membrane markers. The bacterial membranes were then tested for the presence of the polymer. The experiments gave evidence that the copolymer binds to the inner bacterial membrane. Further studies, where the copolymer was incubated with isolated mixed (inner and outer) membrane fractions, proved that the copolymer exerts more destructive effect on E. coli outer membrane. The damaging effect on the membranes is concentration dependent. 47 Refs.
Journal of Materials Science: Materials in Medicine, 27, No.3, 2016, paper 55, pp.14, ISSN: 0957-4530, eISSN: 1573-4838, DOI: 10.1007/s10856-016-5669-6
Jonca J; Tukaj C; Wladyslaw Werel; Mizerska U; Witold Fortuniak; Chojnowski J

1224947 - Silver nanoparticle anchored with novel crosslinked beaded polystyrene/polyamidoxime sequential interpenetrating polymer networks (IPNs) and its antibacterial activity (Downloadable PDF Available)
The present article describes the synthesis of silver nanoparticles (SNPs) impregnatated crosslinked beaded polystyrene/polyamidoxime (PSD/PAMD) interpenetrating polymer networks (IPNs). The developed SNPs-IPNs were tested for the antibacterial activity for water purification. Initially, the crosslinked beaded polystyrene/polyacrylonitrile (PSD/PAN) polymer was synthesised by radical sequential suspension polymerisation method thereafter, it has been converted into PSD/PAMD-IPN comprising amidoxime group, which acts as capping agent to anchor the silver ions. The silver ions impregnated with PSD/PAMD-IPN were converted into SNPs by chemical reduction methodology followed by stabilisation without any deterioration or loss in polymer. IR and solid-state ^13C NMR spectra were use for the structural characterisation of developed SNPs-IPN, while morphological characterisation was examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The size of the SNPs formed with the networks were found less than 5 nm. The disinfection potential of SNPs-IPN was evaluated by different antibacterial test. The bactericidal test of SNPs-IPN revealed the promising antibacterial efficiency with complete microbial inhibition within 4-6 h. The reusability of the SNPs-IPN beads was also tested for its repeated use for industrial application. (43 ref)
Polymer Composites, 37, No.1, 2016, p.70-80, ISSN: 0272-8397, eISSN: 1548-0569, DOI: 10.1002/pc.23156
Saroj Sharma; Sharma C R; Khushbu Bhayani; Sandhya Mishra

1225372 - Synthesis, characterization and biological evaluation of a new photoactive hydrogel against gram-positive and gram-negative bacteria
In 2013, the World Health Organisation reported that 884 million people lack access to clean potable water. Photodynamic antimicrobial chemotherapy (PACT) is a very promising alternative to conventional antibiotics for the efficient inactivation of pathogenic microorganisms. We report the synthesis, characterisation and antibacterial activity of a polyacrylamide-based hydrogel (7), with a new photoactive phenothiazinium compound (6) immobilised on it, to be used as a novel water-sterilising device. The hydrogel was characterised by IR and scanning electron microscopy and incorporation of the dye confirmed by UV-visible spectroscopy. Antibacterial tests using the recombinant bioluminescent Gram-positive Staphylococcus aureus RN4220 and Gram-negative Escherichia coli DH5 (alpha) were performed to assess the ability of the hydrogel to inactivate bacterial strains in solution. The hydrogel is characterised by a non-ordered microporous structure and is able to generate reactive oxygen species. The hydrogel is able to inactivate planktonic cells of the S. aureus and E. coli (3.3 log and 2.3 log killing, respectively) after 25 min of irradiation with white light at 14.5 mW cm^-2. The contact surface does not influence the kill rates while the killing rate increased by increasing the total amount of the hydrogel (0.27 log drop to 1.65 log drop with 0.5 mg cm^-3 to 2.5 mg cm^-3 of total amount of dye). The hydrogel was found to be active for four cycles, suggesting the possibility of reuse and it was shown to be active against both Gram-positive and Gram-negative species with no leaching of the active molecule. (52 ref)
: Journal of Materials Chemistry B, 4, No.8, 2016, p.1499-1509, ISSN: 2050-750X, eISSN: 2050-7518, DOI: 10.1039/c5tb02569a
Cinzia Spagnul; Greenman J; Wainwright M; Kamil Z; Boyle R W

1225467 - Influence of maleated elastomer on filler dispersion, mechanical and antimicrobial properties of hybrid HDPE/clay/silver nanocomposites
This work analyses the effect of using ethylene-propylene-diene-monomer-grafted maleic anhydride (EPDM-g-MA) as compatibiliser to improve the interfacial properties and toughness of high-density polyethylene-organoclay-silver (HDPE/clay/silver) nanocomposites. EPDM-g-MA was reacted using ultrasound with a solution of AgNO"3 0.04M and ethylene glycol using ammonium hydroxide to obtain the silver ammonium complex. This silver-coated maleated EPDM was then melt mixed with HDPE and organoclay (Nanomer I28E) using a twin-screw extruder. Transmission electron microscopy (STEM) and X-ray diffraction (XRD) results confirmed the filler dispersion of both organoclay and silver nanoparticles into HDPE matrix when maleated EPDM was used. Both fillers were better dispersed and exfoliated by using this compatibiliser. The thermal stability enhancement of nanocomposites was confirmed using thermogravimetric analysis. Mechanical and antimicrobial properties demonstrated that better dispersed filler obtained with maleated EPDM enhanced the toughness and antimicrobial behaviour of HDPE/clay/silver hybrid nanocomposites. This confirmed that maleated EPDM was an efficient compatibiliser to obtain hybrid nanocomposites with enhanced properties to be used for several HDPE applications. (28 ref)
Journal of Adhesion Science and Technology, 30, No.9, 2016, p.1006-1016, ISSN: 0169-4243, eISSN: 1568-5616, DOI: 10.1080/01694243.2015.1136136
Sanchez-Valdes S

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