Surface modification of natural rubber latex films via grafting of poly(ethylene glycol) for reduction in protein adsorption and platelet adhesion

A Versatile Approach for the Synthesis of Antimicrobial Polymer Brushes on Natural Rubber/Graphene Oxide Composite Films via Surface-Initiated Atom-Transfer Radical Polymerization

A simple strategy was adopted for the preparation of an antimicrobial natural rubber/graphene oxide (NR/GO) composite film modified through the use of zwitterionic polymer brushes. An NR/GO composite film with antibacterial properties was prepared using a water-based solution-casting method. The composited GO was dispersed uniformly in the NR matrix and compensated for mechanical loss in the process of modification. Based on the high bromination activity of α-H in the structure of cis-polyisoprene, the composite films were brominated on the surface through the use of N-bromosuccinimide (NBS) under the irradiation of a 40 W tungsten lamp. Polymerization was carried out on the brominated films using sulfobetaine methacrylate (SBMA) as a monomer via surface-initiated atom transfer radical polymerization (SI-ATRP). The NR/GO composite films modified using polymer brushes (PSBMAs) exhibited 99.99% antimicrobial activity for resistance to Escherichia coli and Staphylococcus aureus. A novel polymer modification strategy for NR composite materials was established effectively, and the enhanced antimicrobial properties expand the application prospects in the medical field.

Natural rubber latex films with effective growth inhibition against S. aureus via surface conjugated gentamicin

Hospital-associated infections and related complications are of extreme concern in the healthcare sector since biofilms generated over material surfaces not only create turbulence in the healthcare practices followed but also ruin the device performance, and increased medication, leading to significant chances of drug resistance. Natural rubber latex (NRL) being the first choice for the manufacture of several conventional biomedical devices, it is essential to ensure the surfaces of the same are inherently inactive against most microorganisms. This study presents NRL film surface conjugated with a well-known antibiotic, gentamicin through an amide linkage to generate antibacterial activity to the surface with a significant growth inhibition rate, especially against Staphylococcus aureus. The NRL films were surface-oxidized under controlled acidic conditions to generate carboxyl groups exploring the unsaturation of the base monomer unit. The carboxyl group reacts with the amine groups of gentamicin facilitating its surface conjugation. The surface anchoring was authenticated by FTIR-ATR complimented further by contact angle measurement as a function of hydrophilicity and elemental analysis by EDX spectroscopy. The antibacterial efficacy of modified NRL films was evaluated using antibacterial drop test and the results indicated a substantial growth inhibition rate (>60%) against Pseudomonas aeruginosa and Staphylococcus aureus. The study could be further optimized and proposed as a viable route for the conjugation of active molecules over inert polymer molecules.

Advancements in modification of membrane materials over membrane separation for biomedical applications-Review

A comprehensive overview of various modifications carried out on polymeric membranes for biomedical applications has been presented in this review paper. In particular, different methods of carrying out these modifications have been discussed. The uniqueness of the review lies in the sense that it discusses the surface modification techniques traversing the timeline from traditionally well-established technologies to emerging new techniques, thus giving an intuitive understanding of the evolution of surface modification techniques over time. A critical comparison of the advantages and pitfalls of commonly used traditional and emerging surface modification techniques have been discussed. The paper also highlights the tuning of specific properties of polymeric membranes that are critical for their increased applications in the biomedical industry specifically in drug delivery, along with current challenges faced and where the future potential of research in the field of surface modification of membranes.

ADVANCES IN TECHNIQUES AND APPLICATIONS OF RUBBER SURFACE GRAFTING MODIFICATION

To meet the requirement in the application of medical devices, composites, biomaterials, corrosion resistance, and selective adsorptions, rubber surface modification is usually indispensable. Grafting treatment is one of most significate treatment methods. In this paper, we focus on rubber surface grafting modification, including grafting techniques and applications. Different grafting methods—including monomer grafting polymerization and coupling reaction—are covered and compared briefly. The related applications of surface grafting modification techniques, such as improving compatibility of waste rubber as fillers, hydrophobicity and lipophilicity of sponge rubber for oil–water separation, biocompatibility of rubber in the medical field, and forming surface patterns, are demonstrated in detail. The new research directions of surface grafting techniques as well as main challenges in application are also discussed.

Double network hydrogels from polyzwitterions: high mechanical strength and excellent anti-biofouling properties

Polyzwitterionic materials, which have both cationic and anionic groups in the polymeric repeat unit, show excellent anti-biofouling properties and are drawing more attention in the biomedical field. In this study, we have successfully synthesized novel single network hydrogels and double network (DN) hydrogels from the zwitterionic monomer, N-(carboxymethyl)-N,N-dimethyl-2-(methacryloyloxy) ethanaminium, inner salt (CDME). The polyCDME (PCDME) single network hydrogel behaves like a hydrophilic neutral hydrogel and its properties are not sensitive to temperature, pH, or ionic strength over a wide range. DN hydrogels using the poly(2-acrylamido-2-methylpropanesulfonic) (PAMPS) as the first network and PCDME as the second network, having a Young's modulus of 0.2-0.9 MPa, possess excellent mechanical strength (fracture stress: 1.2-1.4 MPa, fracture strain: 2.2-6.0 mm/mm) and toughness (work of extension at fracture: 0.9-2.4 MJ m^-3) depending on the composition ratio of PCDME to PAMPS. The strength and toughness of the optimized PAMPS/PCDME DN is comparable to the normal PAMPS/PAAm DN hydrogels that use poly(acrylamide) (PAAm) as the second network. By macrophage adhesion test, both the PCDME hydrogels and the PAMPS/PCDME DN hydrogels have shown excellent anti-biofouling properties. These results demonstrate that the PCDME-based DN hydrogels have high potential as a novel soft and wet biomaterial.

Elasticity and safety of alkoxyethyl cyanoacrylate tissue adhesives

Cyanoacrylate glues are easily applied to wounds with good cosmetic results. However, they tend to be brittle and can induce local tissue toxicity. A series of cyanoacrylate monomers with a flexible ether linkage and varying side-chain lengths was synthesized and characterized for potential use as tissue adhesives. The effect of side-chain length on synthesis yield, physical and mechanical properties, formaldehyde generation, cytotoxicity in vitro and biocompatibility in vivo were examined. The incorporation of etheric oxygen allowed the production of flexible monomers with good adhesive strength. Monomers with longer side-chains were found to have less toxicity both in vitro and in vivo. Polymerized hexoxyethyl cyanoacrylate was more elastic than its commercially available and widely used alkyl analog 2-octyl cyanoacrylate, without compromising biocompatibility.

Photografted Poly(ethylene glycol) Matrix for Affinity Interaction Studies

A poly(ethylene glycol) (PEG)-based matrix for studies of affinity interactions is developed and demonstrated. The PEG matrix, less than 0.1 microm thick, is graft copolymerized onto a cycloolefin polymer from a mixture of PEG methacrylates using a free radical reaction initiated by UV light at 254 nm. The grafting process is monitored in real time, and characteristics such as thickness, homogeneity, relative composition, photostability, and performance in terms of protein resistance in complex biofluids and sensor qualities are investigated with null ellipsometry, infrared spectroscopy, and surface plasmon resonance. The matrix is subsequently modified to contain carboxyl groups, thereby making it possible to immobilize ligands in a controlled and functional manner. Human serum albumin and fibrinogen are immobilized and successfully detected by antibody recognition using surface plasmon resonance. The results are encouraging and suggest that the PEG matrix is suitable for biochip and biosensor applications in demanding biofluids.

Brush-type amphiphilic diblock copolymers from "living"/controlled radical polymerizations and their aggregation behavior

Two brush-type amphiphilic diblock copolymers, poly(poly(ethylene glycol)methyl ether methacrylate-block-polystyrene) (P(PEGMA)-b-PS) and poly(glycidyl methacrylate)-block-poly(poly(ethylene glycol)methyl ether methacrylate) (P(GMA)-b-P(PEGMA)) were synthesized, respectively, via consecutive atom-transfer radical polymerizations (ATRPs) and reversible addition-fragmentation chain-transfer (RAFT) polymerizations. The diblock copolymers were characterized by gel permeation chromatography (GPC), (1)H nuclear magnetic resonance (NMR) spectroscopy, and FT-IR spectroscopy. The aggregation behavior of the two amphiphilic diblock copolymers in water was also studied. Scanning electron and transmission electron microscopic images revealed that spherical micelles (40-80 nm in diameter) from self-assembly of the P(PEGMA)-b-PS copolymers and wormlike micelles (60-120 nm in length and 20-30 nm in diameter) from self-assembly of the P(GMA)-b-P(PEGMA) copolymers were prevalent. The spherical P(PEGMA)-b-PS micelles could self-assemble gradually into giant aggregates of several micrometers in diameter.

Polymer surface properties and their effect on the adhesion of Proteus mirabilis

A problem encountered in patients undergoing long-term catheterization of the urinary tract is that of encrustation and blockage of the catheter by crystalline bacterial biofilms. This is principally caused by the action of the urease-producing pathogen Proteus mirabilis. A major aim of this work is to develop materials resistant to encrustation. Here, the effects of polymer surface properties on the adhesion of P. mirabilis are examined. Spin-coated polymer films were characterized through contact angle measurements to give the Lifschitz-van der Waals, electron acceptor and electron donor terms of the surface free energy, gamma(s)LW, gamma(s)+ and gamma(s)- respectively. A parallel-plate flow cell was used to assess adhesion to these polymer films of P. mirabilis suspended in an aqueous phosphate buffer, pH 7.4, ionic strength 0.26 mol/kg. P. mirabilis was found to adhere significantly less (p < 0.02) to films of agarose, poly(2-hydroxyethylmethacrylate) and cross-linked poly(vinyl alcohol) than to more hydrophobic materials. These polymer films were found to be strongly electron donating, i.e. possessing large gamma(s)-. Films examined using scanning electron microscopy mostly showed no evidence of roughness down to a scale of 1-10 microm. The better performance is thought to be due to a repulsive interaction with the bacterial surface caused by acid/base-type interactions.