Injectable Slippery Lubricant-Coated Spiky Microparticles with Persistent and Exceptional Biofouling-Resistance

Antibacterial features of material surface: strong enough to serve as antibiotics?

Bacteria are small but need big efforts to control. The use of antibiotics not only produces superbugs that are increasingly difficult to inactivate, but also raises environmental concerns with the growing consumption. It is now believed that the antibacterial task can count on some physiochemical features of material surfaces, which can be anti-adhesive or bactericidal without releasing toxicants. It is necessary to evaluate to what extent can we rely on the surface design since the actual application scenarios will need the antibacterial performance to be sharp, robust, environmentally friendly, and long-lasting. Herein, we review the recent laboratory advances that have been classified based on the specific surface features, including hydrophobicity, charge potential, micromorphology, stiffness and viscosity, and photoactivity, and the antibacterial mechanisms of each feature are included to provide a basic rationale for future design. The significance of anti-biofilms is also introduced, given the big role of biofilms in bacteria-caused damage. A perspective on the potential wide application of antibacterial surface features as a substitute or supplement to antibiotics is then discussed. Surface design is no doubt a solution worthy to explore, and future success will be a result of further progress in multiple directions, including mechanism study and material preparation.

Fabrication of Hierarchical Patterned Surfaces Using a Functionalized CeO2-EPDM Composite for Crevice Corrosion Prevention on High-Voltage Insulators

Crevice corrosion accounts for 62% of the recorded breakdown of insulators utilized in transmission lines, which may interfere with the reliability of power utilities. To address these challenges, sustainable and resilient slippery lubricant-infused porous surfaces (SLIPS) are developed on insulators to prevent electrochemically/biochemically induced crevice corrosion especially occurring in tropical and coastal environments. The conventional way of developing SLIPS by chemical and physical etching might interfere with the mechanical stability of insulators composed of pin (galvanized steel), cement, and shell (porcelain). The current study proposes a noble concept of developing hierarchical patterned textured surfaces on insulators to fabricate a resilient SLIPS coating without physical/chemical etching. The proposed coating exhibits 99% antiadhesion performance against a mixed culture of bacterial strains, superior hydrophobicity (contact angle: 160°, contact angle hysteresis: 4°), and crevice corrosion resistance performance at elevated temperatures (25-75 °C) and humidity. This study could facilitate a new route for the development of sustainable and highly reliable SLIPS coatings in the future.

Lubricant-entrenched Slippery Surface-based Nanocarriers to Avoid Macrophage Uptake and Improve Drug Utilization

INTRODUCTION

Reducing the protein adsorption of nanoparticles (NPs) as drug carriers to slow their rapid clearance by macrophages uptake is a critical challenge for NPs clinical translational applications. Despite extensive research efforts to inhibit cellular uptake, including covering biological agents or surface chemical coatings to impart "stealth" properties to NPs, their stability remains insufficient.

OBJECTIVES

Developed a novel surface modification technology based on a physical infusion engineering approach to achieve persistent inhibition of protein adhesion and cellular uptake by nanocarriers.

METHODS

The nanoparticles were prepared based on conventional drug carrier mesoporous silica NPs through a two-step process. A functional nanoscale slippery surface was formed by grafting "liquid-like" brushes on the particles surface, and then a lubricant-entrenched slippery surfaces (LESS) was formed by infusing silicone oil lubricant into the entire surface. Co-incubation with macrophages (in vitro and in vivo) was used to examine the anti-uptake properties of modified NPs. The anti-adhesion properties of LESS coating surfaces to various liquids, proteins and cells were used to analyze the anti-uptake mechanism. Loaded with drugs, combined with tumor models, to evaluate the drug utilization of modified NPs.

RESULTS

Relying on the stable and slippery LESS coating, the modified surface could prevent the adhesion of various liquids and effectively shield against the adhesion of proteins and cells, as well as remarkably reduce macrophage cellular uptake in vitro and in vivo. In addition, the LESS coating does not affect cell activity and allows NPs to be loaded with drugs, significantly improving the utilization of drugs in vitro and in vivo. This allows the NPs to reach to the target tumor site for drug delivery without active clearance by macrophages.

CONCLUSION

Our research introduces a new nanocarrier technology to improve anti-biofouling performance and stealth efficiency that will facilitate the development of nanomedicines for clinical transformation applications.

Superamphiphilic TiO2 Composite Surface for Protein Antifouling

Unwanted protein adsorption deteriorates fouling processes and reduces analytical device performance. Wettability plays an important role in protein adsorption by affecting interactions between proteins and surfaces. However, the principles of protein adsorption are not completely understood, and surface coatings that exhibit resistance to protein adsorption and long-term stability still need to be developed. Here, a nanostructured superamphiphilic TiO2 composite (TiO2 /SiO2 ) coating that can effectively prevent nonspecific protein adsorption on water/solid interfaces is reported. The confined water on the superamphiphilic surface enables a low adhesion force and the formation of an energy barrier that plays a key role in preventing protein adsorption. This adaptive design protects the capillary wall from fouling in a harsh environment during the bioanalysis of capillary electrophoresis and is further extended to applications in multifunctional microfluidics for liquid transportation. This facile approach is not only perfectly applied in channels with complicated configurations but may also offer significant insights into the design of advanced superwetting materials to control biomolecule adhesion in biomedical devices, microfluidics, and biological assays.

Nanosurfacing Ti alloy by weak alkalinity-activated solid-state dewetting (AAD) and its biointerfacial enhancement effect

Nanoscale manipulation of material surfaces can create extraordinary properties, holding great potential for modulating the implant-bio interface for enhanced performance. In this study, a green, simple and biocompatible nanosurfacing approach based on weak alkalinity-activated solid-state dewetting (AAD) was for the first time developed to nano-manipulate the Ti6Al4V surface by atomic self-rearrangement. AAD treatment generated quasi-periodic titanium oxide nanopimples with high surface energy. The nanopimple-like nanostructures enhanced the osteogenic activity of osteoblasts, facilitated M2 polarization of macrophages, and modulated the cross-talk between osteoblasts and macrophages, which collectively led to significant strengthening of in vivo bone-implant interfacial bonding. In addition, the titanium oxide nanopimples strongly adhered to the Ti alloy, showing resistance to tribocorrosion damage. The results suggest strong nano-bio interfacial effects, which was not seen for the control Ti alloy processed through traditional thermal oxidation. Compared to other nanostructuring strategies, the AAD technique shows great potential to integrate high-performance, functionality, practicality and scalability for surface modification of medical implants.

Wearable and Implantable Intraocular Pressure Biosensors: Recent Progress and Future Prospects

Biosensors worn on or implanted in eyes have been garnering substantial attention since being proven to be an effective means to acquire critical biomarkers for monitoring the states of ophthalmic disease, diabetes. Among these disorders, glaucoma, the second leading cause of blindness globally, usually results in irreversible blindness. Continuous intraocular pressure (IOP) monitoring is considered as an effective measure, which provides a comprehensive view of IOP changes that is beyond reach for the "snapshots" measurements by clinical tonometry. However, to satisfy the applications in ophthalmology, the development of IOP sensors are required to be prepared with biocompatible, miniature, transparent, wireless and battery-free features, which are still challenging with many current fabrication processes. In this work, the recent advances in this field are reviewed by categorizing these devices into wearable and implantable IOP sensors. The materials and structures exploited for engineering these IOP devices are presented. Additionally, their working principle, performance, and the potential risk that materials and device architectures may pose to ocular tissue are discussed. This review should be valuable for preferable structure design, device fabrication, performance optimization, and reducing potential risk of these devices. It is significant for the development of future practical IOP sensors.

Liquid-like Polymer Coating as a Promising Candidate for Reducing Electrode Contamination and Noise in Complex Biofluids

Biosensors that can automatically and continuously track fluctuations in biomarker levels over time are essential for real-time sensing in biomedical and environmental applications. Although many electrochemical sensors have been developed to quickly and sensitively monitor biomarkers, their sensing stability in complex biofluids is disturbed by unavoidable nonspecific adhesion of proteins or bacteria. Recently, various substrate surface modification techniques have been developed to resist biofouling, yet functionalization of electrodes in sensors to be anti-biofouling is rarely achieved. Here, we report an integrated three-electrode system (ITES) modified with a "liquid-like" polydimethylsiloxane (PDMS) brush that can continuously and stably monitor reactive oxygen species (ROS) in complex fluids. Based on the slippery "liquid-like" coating, the modified ITES surface could prevent the adhesion of various liquids as well as the adhesion of proteins and bacteria. The "liquid-like" coating does not significantly affect the sensitivity of the electrode in detecting ROS, while the sensing performance could remain stable and free of bacterial attack even after 3 days of incubation with bacteria. In addition, the PDMS brush-modified ITES (PMITES) could continuously record ROS levels in bacterial-rich fluids with excellent stability over 24 h due to the reduced bacterial contamination on the electrode surface. This technique offers new opportunities for continuous and real-time monitoring of biomarkers that will facilitate the development of advanced sensors for biomedical and environmental applications.

Liquid-like polymer-based self-cleaning coating for effective prevention of liquid foods contaminations

Liquid food containers commonly suffer from inevitable contamination and even biofilm formation due to the adhesion of food residuals or saliva, which requires detergents to clean. Although previously reported superhydrophobic and omniphobic coatings can resist the adhesion of liquids, the requirements of specific nanostructures or infused lubricants limit their applications in food containers. Here, by grafting smooth glass containers with "liquid like" polydimethylsiloxane brushes, we developed a unique approach for preparing a slippery coating that could exhibit highly robust repellency to various liquid foods. The coating was highly transparent and did not induce a significant alteration of the smooth surface. The "liquid like" coating could effectively prevent the adhesion of various liquid foods and inhibit the formation of bacterial biofilms, without the use of detergents for cleaning. Moreover, this coating could resist mechanical damage from friction, and displayed high biocompatibility with biological cells. The slipperiness, smoothness, robustness and biocompatibility of the "liquid like" coating was highly beneficial to practical applications as self-cleaning glass container, which has been challenging to achieve by conventional superhydrophobic or omniphobic coatings. Our study introduced a versatile strategy to functionalize biocompatible surfaces for food containers which reduced the contamination of residues and the use of detergents, and may be beneficial to human and environmental health.

Fluoropolymers in biomedical applications: state-of-the-art and future perspectives

Biomedical applications of fluoropolymers in gene delivery, protein delivery, drug delivery, ¹⁹F MRI, PDT, anti-fouling, anti-bacterial, cell culture, and tissue engineering.

Dynamic Wettability on the Lubricant-Impregnated Surface: From Nucleation to Growth and Coalescence

The surface dynamic wettability during droplet nucleation and growth involved with phase change is different from the static wettability formed from a sessile drop. Revealing this dynamic wettability of the lubricant-impregnated surfaces (LISs) and identification of the consistency between the wettability during condensation and the static wettability are of significant importance. In this study, we investigated condensation of water droplets on LISs using molecular dynamics simulations. All possible morphologies on LISs were investigated considering the effects of interfacial tension and lubricant thickness. The exploration of droplet behaviors from nucleation to growth and coalescence revealed four nucleation mechanisms and six growth modes. The lubricant was observed to be beneficial for the formation of droplets and maintaining dropwise condensation mode. The present investigation also established that the consistency between the wettability during condensation and the static wettability was determined by the solid-water-oil interface and the lubricant thickness. A map was proposed which helps in deciding whether the wettability during condensation is the same as the static wettability on LIS.

Anomalous dispersion of bioinspired flower-like microparticles for oil/water separation

Hydrophobic particles have been suffering from aggregation in aqueous media, which limits their applications in oil/water separation. Surfactants have been used to increase the dispersity of the hydrophobic particles in water, but this approach compromises particles' hydrophobicity and oil absorption capabilities. Recently, hierarchical microparticles decorated with nanospikes were found to exhibit long-term anomalous dispersion in liquid medium without adding any surfactants. However, whether this anomalous dispersion phenomenon was applicable to 2D nano-petals decorated microparticles still remains unknown. Here, we developed a ZnO-based flower-like microparticles (FLMPs) whose surfaces were attached with 2D nano-petals, and we examined their anomalous dispersity. Our results showed that both hydrophilic and hydrophobic FLMPs could achieve anomalous dispersity either in water or organic solvents, likely due to reduced interparticle collision by the 2D nano-petals. In addition, the functional hydrophobic FLMPs also possessed a large surface area and superhydrophobic surfaces to efficiently absorb oil spills on water and oil emulsion suspended in water. In contrast, the hydrophobic microbeads (MBs) without nano-petals structure seriously aggregated in water and exhibited reduced oil absorption abilities. Our work demonstrated the new finding of 2D nano-pedal structure-mediated anomalous dispersity, and provided a new method for effective oil/water separation using superhydrophobic particles without surfactants.

Metallic Fe-Au Barcode Nanowires as a Simultaneous T Cell Capturing and Cytokine Sensing Platform for Immunoassay at the Single-Cell Level

Barcode nanowires (BNWs) composed of multiple layered segments of different materials are attractive to bioengineering field due to their characteristics that allow the adjustment of physicochemical properties and conjugation with two or more types of biomolecules to facilitate multiple tasks. Here, we report a metallic Fe (iron)-Au (gold) BNW-based platform for capturing CD8 T cells and the interferon-γ (γ) they secrete, both of which play key roles in controlling infectious diseases such as tuberculosis, at the single-cell level. We also describe an efficient approach for conjugating distinct antibodies, which recognize different epitopes to appropriate materials. The platform achieved detection even with 4.45-35.6 μg mL^-1 of BNWs. The T cell capture efficiency was close to 100% and the detection limit for interferon-γ was 460 pg mL^-1. This work presents a potential guideline for the design of single-cell immunoassay platforms for eliminating diagnostic errors by unambiguously identifying disease-relevant immune mediators.