Self-Cross-Linkable Maleic Anhydride Terpolymer Coating with Inherent High Antimicrobial Activity and Low Cytotoxicity

Developing coating materials with low cytotoxicity and high antimicrobial activity has been recognized as an effective way to prevent medical device-associated infections. In this study, a maleic anhydride terpolymer (PPTM) is synthesized and covalently attached to silicone rubber (SR) surface. The formed coating can be further cross-linked (SPM) through the self-condensation of pendent siloxane groups of terpolymer. No crack or delamination of SPM was observed after 500 cycles of bending and 7 day immersion in deionized water. The sliding friction force of a catheter was reduced by 50% after coating with SPM. The SPM coating without adding any extra antibacterial reagents can kill 99.99% of Staphylococcus aureus and Escherichia coli and also significantly reduce bacterial coverage, while the coating displayed no antimicrobial activity when maleic anhydride groups of SPM were aminated or hydrolyzed. The results of the repeated disinfection tests showed that the SR coated with SPM could maintain 87.3% bactericidal activity within 5 cycles. Furthermore, the SPM coating only imparted slight toxic effect (>85% viability) on L929 cells after 36 h of coculture, which is superior to the coating of aminated SPM conjugated with the antimicrobial peptide E6. The terpolymer containing maleic anhydride units have great potential as a flexible and durable coating against implant infections.

Nanoplastics released from daily used silicone and latex products during mechanical breakdown

Waste of polymer products, especially plastics, in nature has become a problem that caught the awareness of the general public during the last decade. The macro- and micro polymers in nature will be broken down by naturally occurring events such as mechanical wear and ultra-violet (UV) radiation which will result in the generation of polymeric particles in the nano-size range. We have recently shown that polystyrene and high-density polyethylene macroplastic can be broken down into nano-sized particles by applying mechanical force from an immersion blender. In this article, we show that particles in the nano-size range are released from silicone and latex pacifiers after the same treatment. Additionally, boiling the pacifiers prior to the mechanical breakdown process results in an increased number of particles released from the silicone but not the latex pacifier. Particles from the latex pacifier are acutely toxic to the freshwater filter feeding zooplankter Daphnia magna.

Biomedical Silicones: Leveraging Additive Strategies to Propel Modern Utility

Silicones have a long history of use in biomedical devices, with unique properties stemming from the siloxane (Si-O-Si) backbone that feature a high degree of flexibility and chemical stability. However, surface, rheological, mechanical, and electrical properties of silicones can limit their utility. Successful modification of silicones to address these limitations could lead to superior and new biomedical devices. Toward improving such properties, recent additive strategies have been leveraged to modify biomedical silicones and are highlighted herein.

Radiation curable polysiloxane: synthesis to applications

Among the different types of specialty polymers, polysiloxane finds its position in the pyramid's apex in terms of its performance attributes. Its unique structural features result in it having superior performance benefits over wide operational conditions. Hence, polysiloxanes are used in various industries. Like other polymers, to effectively use polysiloxanes, curing is a non-negotiable fact. Therefore, polysiloxanes are cured using different chemistries such as addition, condensation, and peroxy-mediated methods, etc. However, recently, it has been noted that there is a strong impetus towards developing radiation-curable polysiloxanes. A faster turnover time, higher yield, and marginal involvement in the release of any toxic by-products has resulted in the widespread acceptance of radiation curing techniques. This review article provides insight into the various facets of polysiloxane chemistry, the synthesis of radiation curable polysiloxane, and the curing methodology of polysiloxane using radiation sources such as ultraviolet, electron beam, and gamma radiation. We further provide an account of the various applications of such radiation-curable polysiloxanes.

A biostable, anti-fouling zwitterionic polyurethane-urea based on PDMS for use in blood-contacting medical devices

Polydimethylsiloxane (PDMS) is commonly used in medical devices because it is non-toxic and stable against oxidative stress. Relatively high blood platelet adhesion and the need for chemical crosslinking through curing, however, limit its utility. In this research, a biostable PDMS-based polyurethane-urea bearing zwitterion sulfobetaine (PDMS-SB-UU) was synthesized for potential use in the fabrication or coating of blood-contacting devices, such as a conduits, artificial lungs, and microfluidic devices. The chemical structure and physical properties of synthesized PDMS-SB-UU were confirmed by 1H-nuclear magnetic resonance (1H-NMR), X-ray diffraction (XRD), and uniaxial stress-strain curve. In vitro stability of PDMS-SB-UU was confirmed against lipase and 30% H2O2 for 8 weeks, and PDMS-SB-UU demonstrated significantly higher resistance to fibrinogen adsorption and platelet deposition compared to control PDMS. Moreover, PDMS-SB-UU showed a lack of hemolysis and cytotoxicity with whole ovine blood and rat vascular smooth muscle cells (rSMCs), respectively. The PDMS-SB-UU was successfully processed into small-diameter (0.80 ± 0.05 mm) conduits by electrospinning and coated onto PDMS- and polypropylene-based blood-contacting biomaterials due to its unique physicochemical characteristics from its soft- and hard- segments.

A facile modification to improve the biocompatibility and adsorbability of activated carbon with zwitterionic hydrogel

In this work, poly(carboxybetaine methacrylate) hydrogel (pCBMA) was employed to modify the activated carbon (AC) for improving the biocompatibility and adsorption capacity of AC in biological environments. First, size-controlled hydrogel beads and hydrogel coated AC (pCBMA-AC) were fabricated with a homemade device, and the preparation conditions were optimized. Then the physical and biological properties of pCBMA-AC with different diameters were investigated. 2 mm pCBMA-AC dispalyed excellent stability with leakage rate only 0.16% after 72 h shaking incubation, as well as remarkable biocompatibility with merely 0.13% hemolysis rate and 3.41% cell death, while 14.72% and 70.11% for the bare AC, respectively, indicating the acceptable lower hemolysis and cytotoxicity according to ISO 10993. Furthermore, the adsorption capacities of pCBMA-AC were evaluated in biological environments with methylene blue as model molecules. The pCBMA-AC displayed 93.50% and 97.32% adsorption rates in BSA solution and FBS, respectively, but only 70.33% and 40.26% for the uncoated AC. These results indicated that pCBMA endows AC remarkable biocompatibility and adsorption capacity, which could extend the applications of AC in biological environments.

Fifty Years of Hydrosilylation in Polymer Science: A Review of Current Trends of Low-Cost Transition-Metal and Metal-Free Catalysts, Non-Thermally Triggered Hydrosilylation Reactions, and Industrial Applications

Hydrosilylation reactions, the (commonly) anti-Markovnikov additions of silanes to unsaturated bonds present in compounds such as alkenes and alkynes, offer numerous unique and advantageous properties for the preparation of polymeric materials, such as high yields and stereoselectivity. These reactions require to be catalyzed, for which platinum compounds were used in the initial stages. Celebrating the 50th anniversary of hydrosilylations in polymer science and, concomitantly, five decades of continuously growing research, hydrosilylation reactions have advanced to a level that renders them predestined for transfer into commercial products on the large scale. Facing this potential transfer, this review addresses and discusses selected current trends of the scientific research in the area, namely low-cost transition metal catalysts (focusing on iron, cobalt, and nickel complexes), metal-free catalysts, non-thermally triggered hydrosilylation reactions (highlighting stimuli such as (UV-)light), and (potential) industrial applications (highlighting the catalysts used and products manufactured). This review focuses on the hydrosilylation reactions involving alkene reactants.

Aziridine-functionalized polydimethylsiloxanes for tailorable polymeric scaffolds: aziridine as a clickable moiety for structural modification of materials

The utility of aziridine as a clickable moiety for post-modification of polydimethylsiloxane is demonstrated.

Dual-function antibacterial surfaces for biomedical applications

Bacterial attachment and the subsequent formation of biofilm on surfaces of synthetic materials pose a serious problem in both human healthcare and industrial applications. In recent decades, considerable attention has been paid to developing antibacterial surfaces to reduce the extent of initial bacterial attachment and thereby to prevent subsequent biofilm formation. Briefly, there are three main types of antibacterial surfaces: bactericidal surfaces, bacteria-resistant surfaces, and bacteria-release surfaces. The strategy adopted to develop each type of surface has inherent advantages and disadvantages; many efforts have been focused on the development of novel antibacterial surfaces with dual functionality. In this review, we highlight the recent progress made in the development of dual-function antibacterial surfaces for biomedical applications. These surfaces are based on the combination of two strategies into one system, which can kill attached bacteria as well as resisting or releasing bacteria. Perspectives on future research directions for the design of dual-function antibacterial surfaces are also provided.

Preparation of anti-fouling silicone elastomers by covalent immobilization of carboxybetaine

The surface-grafted carboxybetaine (CB) layer could enhance the biocompatibility of polydimethylsiloxane (PDMS) and reduce the adsorption of protein and adhesion of bacteria efficiently.