Functional modification of polydimethylsiloxane nanocomposite with silver nanoparticles-based montmorillonite for antibacterial applications

Preparation of Polyaniline-Modified Cellulose/PDMS Composite Triboelectric Material and Application of Its Pretreatment in MOW Pulp

Self-powered electronic equipment has rapidly developed in the fields of sensing, motion monitoring, and energy collection, posing a greater challenge to triboelectric materials. Triboelectric materials need to enhance their electrical conductivity and mechanical strength to address the increasing demand for stability and to mitigate unpredictable physical damage. In this study, polyaniline-modified cellulose was prepared by means of in situ polymerization and compounded with polydimethylsiloxane, resulting in a triboelectric material with enhanced strength and conductivity. The material was fabricated into a tubular triboelectric nanogenerator (TENG) (G-TENG), and an electrocatalytic pretreatment of mixed office waste paper (MOW) pulp was performed using papermaking white water as the flowing liquid to improve the deinking performance. The electrical output performance of G-TENG is highest at a flow rate of 400 mL/min, producing a voltage of 22.76 V and a current of 1.024 μA. Moreover, the deinking effect of MOW was enhanced after the electrical pretreatment. This study explores the potential application of G-TENG as a self-powered sensor power supply and emphasizes its prospect as an energy collection device.

Antimicrobial Peptide Assembly on Zwitterionic Polymer Films to Slow Down Biofilm Formation

Formation of biofilms on equipment used in various fields, such as medicine, domestic sanitation, and marine transportation, can cause serious problems. The use of antibiofouling and bactericidal modifications is a promising strategy for inhibiting bacterial adhesion and biofilm formation. To further enhance the antibiofilm properties of a surface, various combinations of bactericidal modifications alongside antibiofouling modifications have been developed. Optimization of the arrangements of antimicrobial peptides on the antibiofouling surface would allow us to design longer-life antibiofilm surface modifications. In this study, a postmodification was conducted with different design using the antimicrobial peptide KR12 on an antibiofouling copolymer film consisting of 2-methacryloyloxyethyl phosphorylcholine, 3-methacryloxypropyl trimethoxysilane, and 3-(methacryloyloxy) propyl-tris(trimethylsilyloxy) silane. The distance of KR12 from the film was adjusted by combining different lengths of poly(ethylene glycol) (PEG) spacers (molecular weights are 2000 and 5000). The density of KR12 was ranged from 0.06 to 0.22 nm-2. When these modified surfaces were exposed to a nutrient-rich TSB suspension, the bacterial area formed by E. coli covered 5-127% of the original copolymer film. We found that a significant distance between the bactericidal and antibiofouling modifications, along with a higher density of bactericidal modifications, slows down the biofilm formation.

Self-Healing Antimicrobial Silicones-Mechanisms and Applications

Organosilicon polymers (silicones) are an important part of material chemistry and a well-established commercial product segment with a wide range of applications. Silicones are of enduring interest due to their unique properties and utility. Recently, new application areas for silicone-based materials have emerged, such as stretchable electronics, wearable stress sensors, smart coatings, and soft robotics. For this reason, research interest over the past decade has been directed towards new methods of crosslinking and increasing the mechanical strength of polyorganosiloxanes. The introduction of self-healing mechanisms may be a promising alternative for such high-value materials. This approach has gained both growing research interest and a rapidly expanding range of applications. Inherent extrinsic and intrinsic self-healing methods have been used in the self-healing of silicones and have resulted in significant advances in polymer composites and coatings, including multicomponent systems. In this review, we present a summary of research work dedicated to the synthesis and applications of self-healing hybrid materials containing polysiloxane segments, with a focus on antimicrobial and antifouling coatings.

Fabrication of antibacterial polydopamine-carboxymethyl cellulose-Ag nanoparticle hydrogel coating for urinary catheters

Urinary tract infections caused by catheter insertion are prevalent in hospital clinics, which can induce serious complications such as bacteriuria and sepsis, and even lead to patient death. The disposable catheters currently used in clinical practice suffer from poor biocompatibility and high infection rate. In this paper, we developed a polydopamine (PDA)-carboxymethylcellulose (CMC)-Ag nanoparticles (AgNPs) coating with both good antibacterial and anti-adhesion properties to bacteria on the surfaces of a disposable medical latex catheter by a simple dipping method. The antibacterial efficiency of the coated catheters against Gram-negative E. coli and Gram-positive S. aureus bacteria was evaluated with both inhibition zone tests and fluorescence microscopy. Compared with the untreated catheter, the PDA-CMC-AgNPs coated catheters showed both good antibacterial and anti-adhesion properties to bacteria, which inhibited the adhesion of live bacteria and dead bacteria by 99.0% and 86.6%, respectively. This novel PDA-CMC-AgNPs composite hydrogel coating has great potential in applications in catheters and other biomedical devices to reduce infections.

The Additive Manufacturing Approach to Polydimethylsiloxane (PDMS) Microfluidic Devices: Review and Future Directions

This paper presents a comprehensive review of the literature for fabricating PDMS microfluidic devices by employing additive manufacturing (AM) processes. AM processes for PDMS microfluidic devices are first classified into (i) the direct printing approach and (ii) the indirect printing approach. The scope of the review covers both approaches, though the focus is on the printed mold approach, which is a kind of the so-called replica mold approach or soft lithography approach. This approach is, in essence, casting PDMS materials with the mold which is printed. The paper also includes our on-going effort on the printed mold approach. The main contribution of this paper is the identification of knowledge gaps and elaboration of future work toward closing the knowledge gaps in fabrication of PDMS microfluidic devices. The second contribution is the development of a novel classification of AM processes from design thinking. There is also a contribution in clarifying confusion in the literature regarding the soft lithography technique; this classification has provided a consistent ontology in the sub-field of the fabrication of microfluidic devices involving AM processes.

A Review on Montmorillonite-Based Nanoantimicrobials: State of the Art

One of the crucial challenges of our time is to effectively use metal and metal oxide nanoparticles (NPs) as an alternative way to combat drug-resistant infections. Metal and metal oxide NPs such as Ag, Ag₂O, Cu, Cu₂O, CuO, and ZnO have found their way against antimicrobial resistance. However, they also suffer from several limitations ranging from toxicity issues to resistance mechanisms by complex structures of bacterial communities, so-called biofilms. In this regard, scientists are urgently looking for convenient approaches to develop heterostructure synergistic nanocomposites which could overcome toxicity issues, enhance antimicrobial activity, improve thermal and mechanical stability, and increase shelf life. These nanocomposites provide a controlled release of bioactive substances into the surrounding medium, are cost effective, reproducible, and scalable for real life applications such as food additives, nanoantimicrobial coating in food technology, food preservation, optical limiters, the bio medical field, and wastewater treatment application. Naturally abundant and non-toxic Montmorillonite (MMT) is a novel support to accommodate NPs, due to its negative surface charge and control release of NPs and ions. At the time of this review, around 250 articles have been published focusing on the incorporation of Ag-, Cu-, and ZnO-based NPs into MMT support and thus furthering their introduction into polymer matrix composites dominantly used for antimicrobial application. Therefore, it is highly relevant to report a comprehensive review of Ag-, Cu-, and ZnO-modified MMT. This review provides a comprehensive overview of MMT-based nanoantimicrobials, particularly dealing with preparation methods, materials characterization, and mechanisms of action, antimicrobial activity on different bacterial strains, real life applications, and environmental and toxicity issues.