Rational design of antibiotic-free antimicrobial contact lenses: Trade-offs between antimicrobial performance and biocompatibility

Microbial keratitis associated with contact lenses (CLs) wear remains a significant clinical concern. Antibiotic therapy is the current standard of care. However, the emergence of multidrug-resistant pathogens necessitates the investigation of alternative strategies. Antibiotic-free antimicrobial contact lenses (AFAMCLs) represent a promising approach in this regard. The effectiveness of CLs constructed with a variety of antibiotic-free antimicrobial strategies against microorganisms has been demonstrated. However, the impact of these antimicrobial strategies on CLs biocompatibility remains unclear. In the design and development of AFAMCLs, striking a balance between robust antimicrobial performance and optimal biocompatibility, including safety and wearing comfort, is a key issue. This review provides a comprehensive overview of recent advancements in AFAMCLs technology. The focus is on the antimicrobial efficacy and safety of various strategies employed in AFAMCLs construction. Furthermore, this review investigates the potential impact of these strategies on CLs parameters related to wearer comfort. This review aims to contribute to the continuous improvement of AFAMCLs and provide a reference for the trade-off between resistance to microorganisms and wearing comfort. In addition, it is hoped that this review can also provide a reference for the antimicrobial design of other medical devices.

Nanozyme-Cosmetic Contact Lenses for Ocular Surface Disease Prevention

Efficiently balancing excess reactive oxygen species (ROS) caused by various factors on the ocular surface is a promising strategy for preventing the development of ocular surface diseases (OSDs). Nevertheless, the conventional topical administration of antioxidants is limited in efficacy due to poor absorption, rapid metabolism, and irreversible depletion, which impede their performance. To address this issue, contact lenses embedded with antioxidant nanozymes that can continuously scavenge ROS, thereby providing an excellent preventive effect against OSDs are developed. Specifically, Prussian blue family nanozymes are chosen based on their multiple antioxidant enzyme-like activities and excellent biocompatibility. The diverse range of colors made them promising candidates for the development of cosmetic contact lenses (CCLs) as a substitute for conventional pigments. The efficacy of nanozyme-CCLs is demonstrated in rabbits and rats exposed to a high risk of developing OSDs. These OSDs' prevention nanozyme-CCLs can pave the way for CCLs toward powerful wearable biomedical devices and provide novel strategies for the rational utilization of nanomaterials in clinical practice.

Superhydrophilic Poly(2-hydroxyethyl methacrylate) Hydrogel with Nanosilica Covalent Coating: A Promising Contact Lens Material for Resisting Tear Protein Deposition and Bacterial Adhesion

Tear protein deposition and bacterial adhesion are the main drawbacks of the hydrogel contact lens. In this study, we developed a novel superhydrophilic poly(2-hydroxyethyl methacrylate) (NSCC-pHEMA) hydrogel with nanosilica covalent coating by the combination of colloidal silica immersion and dehydration treatment. The infrared spectroscopy and energy dispersive X-ray spectroscopy analyses confirmed the successful formation of Si-O covalent bonding between nanosilica and pHEMA hydrogel. This coating was highly stable against powerful sonication or long-term shaking immersion treatment. Among various NSCC-pHEMA hydrogels with different colloidal silica concentrations, the 7%NSCC-pHEMA hydrogel generated a superhydrophilic micro wrinkle surface with a root-mean-square roughness of 43.10 nm, which dramatically reduced the deposition of lysozyme and bovine serum albumin by 65% and 57%, respectively, and decreased the adhesion of S. aureus and E. coli by 59% and 66%, respectively, in comparison to the pHEMA hydrogel. However, the nanosilica coating had little effect on the mechanical properties, light transmittance, oxygen permeability, and equilibrium water content of the pHEMA hydrogel. NSCC-pHEMA hydrogels were nontoxic to both mouse fibroblasts (L929) and human immortalized keratinocytes (HaCaT). Thus, the superhydrophilic NSCC-pHEMA hydrogel is a potential contact lens material for resisting tear protein deposition and bacterial adhesion.

Sustained Release of a Polymeric Wetting Agent from a Silicone-Hydrogel Contact Lens Material

Uptake and release kinetics are investigated of a dilute aqueous polymeric-surfactant wetting agent, (ethylene oxide)₄₅-(butylene oxide)₁₀ copolymer, also referred to as poly(oxyethylene)-co-poly(oxybutylene), impregnated into a newly designed silicone-hydrogel lens material. Transient scanning concentration profiles of the fluorescently tagged polymeric surfactant follow Fick's second law with a diffusion coefficient near 10^-11 cm²/s, a value 3-4 orders smaller than that of the free surfactant in bulk water. The Nernst partition coefficient of the tagged polymeric wetting agent, determined by fluorescence microscopy and by methanol extraction, is near 350, a very large value. Back-extraction of the polymeric-surfactant wetting agent releases only ∼20% of the loaded amount after soaking the fully loaded lens for over 7 days. The remaining ∼80% is irreversibly bound in the lens matrix. Reverse-phase liquid chromatography of the lens-loaded and lens-extracted surfactant demonstrates that the released wetting agent is more hydrophilic with a higher polarity. Aqueous poly(oxyethylene)-co-poly(oxybutylene) is hypothesized to attach strongly to the lens matrix, most likely to the lens silicone domains. Strong binding leads to slow transient diffusion, to large uptake, and to significant irreversible retention. These characteristics indicate the suitability of using a poly(oxyethylene)-co-poly(oxybutylene) nonionic polymeric surfactant to maintain enhanced lens wettability over time. Methodology and findings from this study provide useful insights for designing sustained-release contact-lens wetting agents and materials.

Development of Poly(2-Methacryloyloxyethyl Phosphorylcholine)-Functionalized Hydrogels for Reducing Protein and Bacterial Adsorption

A series of hydrogels with intrinsic antifouling properties was prepared via surface-functionalization of poly(2-hydroxyethyl methacrylate) [p(HEMA)]-based hydrogels with the biomembrane-mimicking zwitterionic polymer, poly(2-methacryloyloxyethyl phosphorylcholine) [p(MPC)]. The p(MPC)-modified hydrogels have enhanced surface wettability, high water content retention (61.0%-68.3%), and good transmittance (>90%). Notably, the presence of zwitterionic MPC moieties at the hydrogel surfaces lowered the adsorption of proteins such as lysozyme and bovine serum albumin (BSA) by 73%-74% and 59%-66%, respectively, and reduced bacterial adsorption by approximately 10%-73% relative to the unmodified control. The anti-biofouling properties of the p(MPC)-functionalized hydrogels are largely attributed to the dense hydration layer formed at the hydrogel surfaces by the zwitterionic moieties. Overall, the results demonstrate that biocompatible and antifouling hydrogels based on p(HEMA)-p(MPC) structures have promising potential for application in biomedical materials.

Reduction in protein absorption on ophthalmic lenses by PEGDA bulk modification of silicone acrylate-based formulation

The absorption of protein and formation of biofilms on the surface of ophthalmic lenses is one of the factors that destroy their useful performance by causing severe visual impairment, inflammation, dryness and ultimate eye discomfort. Therefore, eye lenses need to be resilient to protein absorption, which is one of the opacity factors in minimizing protein absorption on the lenses. The purpose of this study was to investigate and reduce sediment biotransformation on the surface of the semi-hardened lens based on acrylate by bulk-free radical polymerization method. In this respect, the effect of poly(ethylene glycol) diacrylate (PEGDA) with two different molecular weights of 200 and 600 g/mol on the surface roughness, protein absorption, and hydrophilicity of the lenses were studied. The surface hardness of the lenses, on shore D scale, was measured using a durometer hardness test. The presence of higher molecular weight of PEGDA hydrophilic polymeric monomers reduced the hardness of the lenses. The effect of introducing PEGDA, with two molecular weights, into lens fabrication formulations was studied with respect to their water content parameters and hydrophilicity. The presence of a crosslinker such as poly(ethylene glycol) diacrylates, at two different molecular weights, increased the water content and hydrophilicity of the produced lenses. Surface roughness is associated with the formation of bio-film and accumulation of microorganisms on the surface. Due to the roughness of the lens surface developed in this research, the lenses containing PEGDA 600 exhibited less roughness compared to that of PEGDA 200, which could also affect the absorption of protein. Therefore, according to the results of protein absorption test, the PEGDA 600 lenses showed lower protein absorption, which could be due to their high degree of water absorption and hydrophilicity.

Effect of antifouling dendrimers and Au DENPs on the enhancement of PCR amplification

The polymerase chain reaction (PCR) has been considered as one of the most fundamental techniques to amplify and analyze specific DNA fragments in the field of molecular biology and clinical medicine. Recently, a variety of nanoparticles (NPs) have been regarded as a novel method to enhance both the quality and yield of PCR technique. Herein, we report the use of generation 5 (G5) poly(amidoamine) (PAMAM) dendrimers and dendrimer-entrapped gold nanoparticles (Au DENPs) modified with polyethylene glycol (PEG) moieties and (or) acetyl groups as a novel class of enhancers to improve the PCR amplification. We set up the nonspecific PCR and two-round PCR as model systems to investigate mechanisms of enhanced PCR. Our results show that dendrimer-based derivatives seem to enhance the PCR specificity. It is worth noting that the modification of antifouling PEG significantly lowered the optimization capability of the corresponding dendrimers, although this inhibition effect can be remarkably compromised by the entrapment of Au NPs. Furthermore, we found that in the presence of Au NPs, the thermal conductivity induced by Au NPs could play the dominant role in the PCR optimization, whereas in the absence of Au NPs, the electrostatic interaction of the dendrimers with PCR components may be the major factor affecting the PCR system. Our results also showed that the optimal concentrations of the materials in the two test systems were very close, which indicates that the developed dendrimer derivatives with good thermal stability may be the efficient PCR additives for enhancing different PCR systems.

Non-sticky and antimicrobial zwitterionic nanocomposite dressings for infected chronic wounds

Zwitterionic poly(sulfobetaine acrylamide) (pSBAA)-based nanocomposite hydrogels can have high potential for the treatment of infected chronic wounds.

Mechanistic Studies of Enhanced PCR Using PEGylated PEI-Entrapped Gold Nanoparticles

The polymerase chain reaction (PCR) is considered an excellent technique and is widely used in both molecular biology research and various clinical applications. However, the presence of byproducts and low output are limitations generally associated with this technique. Recently, the use of nanoparticles (NPs) has been shown to be very effective at enhancing PCR. Although mechanisms underlying this process have been suggested, most of them are mainly based on PCR results under certain situations without abundant systematic experimental strategy. In order to overcome these challenges, we synthesized a series of polyethylene glycol (PEG)-modified polyethylenimine (PEI)-entrapped gold nanoparticles (PEG-Au PENPs), each having different gold contents. The role of the synthesized NPs in improving the PCR technique was then systematically evaluated using the error-prone two-round PCR and GC-rich PCR (74% GC content). Our results suggest a possible mechanism of PCR enhancement. In the error-prone two-round PCR system, the improvement of the specificity and efficiency of the technique using the PEG-Au PENPs mainly depends on surface-charge-mediated electrostatic interactions. In the GC-rich PCR system, thermal conduction may be the dominant factor. These important findings offer a breakthrough in understanding the mechanisms involved in improving PCR amplification, as well as in the application of nanomaterials in different fields, particularly in biology and medicine.