Fabrication of Slippery Liquid-Infused Coatings in Flexible Narrow-Bore Tubing

Unraveling the anti-biofouling mechanisms of slippery liquid-infused porous surface from molecular interaction perspective

Newly developed slippery liquid-infused porous surfaces (SLIPS) exhibit highly effective anti-fouling performance without harming organisms, making them a promising solution for both environmental and material protection. However, previous studies have primarily understood the anti-fouling effects of SLIPS from a mechanical perspective, neglecting the atomic interactions involved in the anti-fouling process. In this study, we combined microbiological experiments with multi-scale simulations to elucidate the microscopic mechanisms behind the unique anti-biofouling effects of SLIPS. After developing SLIPS with robust liquid-repellency, we characterized its physical and chemical properties and demonstrated its superior effectiveness in preventing Pseudomonas aeruginosa attachment. To probe the initial contact during bacterial attachment, all-atom molecular dynamics (MD) simulations were conducted, revealing that the liquid-liquid interface suppresses the effective pilin adhesion on SLIPS. Further analysis through steered MD, ab initio MD, and density functional theory calculations revealed that the flexible siloxane backbone and the non-polar nature of silicone oil molecules enhance the diffusivity of interfacial water and lead to the continuous nanoscale fluctuation of liquid-liquid interface, thus inhibiting the role of protein dynamics in promoting bio-adhesion. These novel insights into the characteristics of liquid-liquid and nano-bio interface during the anti-biofouling process of SLIPS may promote the future development of bio-inspired functional surfaces.

Sprayable Biocide-Free Polyurethane Paint that Reduces Biofouling and Facilitates Removal of Pathogenic Bacteria from Surfaces

The ability to prevent bacterial adhesion on surfaces and to facilitate the removal of bacteria once they have already contaminated or colonized a surface is important in a broad range of fundamental and applied contexts. The work reported here sought to characterize the physicochemical properties of a family of biocide-free hydrophobic polyurethane coatings containing polysiloxane segments and evaluate their ability to mitigate bacterial fouling and/or facilitate subsequent surface cleaning after exposure to pathogenic bacteria. We developed benchtop microbiological assays to characterize surface fouling and subsequent removal of bacteria after repeated (i) short-term intermittent physical contact with and (ii) longer-term continuous flow-based contact with liquid growth media containing either S. aureus or E. coli, two common Gram-positive or Gram-negative bacterial pathogens, respectively. Characterization of fouled and cleaned surfaces using fluorescence microscopy and standard agar-based plaque assays revealed significant differences in both reductions in initial fouling and subsequent cleanability after gentle rinsing with water. These differences correlated to differences in the surface properties of these materials (e.g., hydrophobicity and contact angle hysteresis), with coatings exhibiting lower contact angle hysteresis generally having the greatest antibiofouling and easy-to-clean properties. Our results suggest that these biocide-free, siloxane-containing polyurethane-based clearcoat materials show significant promise for the mitigation of surface fouling and bacterial adhesion, which could prove useful in a range of commercial applications, including in "high touch" environments where microbial contamination is endemic.

Antifouling slippery liquid infused porous surface for surfactant-free PCR on digital microfluidics platform

Digital microfluidics technology has immense potential for multiplexing biological processes, reducing reagents, and minimizing process time. However, biofouling of surfaces causes cross-contamination, slow droplet movement, and prolonged experiment time, hindering its full potential. Traditionally surfactants are used to combat this issue but can interfere with biological reactions leading to low efficiency. An alternative is the use of slippery liquid-infused porous surfaces (SLIPS), which do not interfere with the reactions and offer a solution to the biofouling problem. In this study, we compare Teflon surfaces with SLIPS to address the challenge of biofouling in Digital MicroFluidic (DMF) devices. More specifically, we demonstrate that SLIPS in an Electrowetting-on-Dielectric (EWOD)-based DMF device not only prevents biofouling but also enhances PCR efficiency, reducing reaction times and reagent consumption. These advancements eliminate the need for surfactants, which can interfere with biological reactions, thereby ensuring higher fidelity in PCR amplification. Our findings reveal that SLIPS facilitate faster droplet movement and maintain reaction integrity, showcasing their potential for high-throughput biological assays.

Recent advances in bio-inspired ionic liquid-based interfacial materials from preparation to application

Natural creatures always display unique and charming functions, such as the adhesion of mussels and the lubrication of Nepenthes, to maintain their life activities. Bio-inspired interfacial materials infused with liquid, especially for ionic liquids (ILs), have been designed and prepared to meet the emerging and rising needs of human beings. In this review, we first summarize the recent development of bio-inspired IL-based interfacial materials (BILIMs), ranging from the synthesis strategy to the design principle. Then, we discuss the advanced applications of BILIMs from anti-adhesive aspects (e.g., anti-biofouling, anti-liquid fouling, and anti-solid fouling) to adhesive aspects (e.g., biological sensor, adhesive tape, and wound dressing). Finally, the current limitations and future prospects of BILIMs are provided to feed the actual needs.

Slippery Shape Memory Tube for Smart Droplet Transportation

Recently, research about controllable droplet transportation in tubes has aroused increased interest. However, existing strategies mainly depend on the elastic tube's shape variation that needs constant external stimuli. Meanwhile, these reported tubes are only suitable for wetting liquids. To achieve the transportation of diverse liquids, different coatings are needed to modify the tube's inner surface to realize complete wetting of different liquids. Herein, we advance a design principle by combining a shape memory polymer (SMP) tube and Nepenthes pitcher plant-inspired slippery surface, which can solve the above-mentioned problems. The SMP offers a tunable tube shape owing to its shape memory effect (SME); the slippery surface reduces the adhesion and expands the applicable range of liquids. Transportation of both water and oils in a wide range of surface tension values can be smartly controlled. The results show that not only the transportation speed and direction can be adjusted but also diverse modes including round-trip transportation, segmented transportation, and antigravity transportation can be achieved. Moreover, applications of the tube in batch inspection of different droplets and step-by-step control of multiple microreactions are also displayed. This work reports a strategy for droplet transportation control based on the tube's SME, which initiates some fresh ideas for designing new superwetting materials toward smart liquid transportation.

Slippery Antifouling Polymer Coatings Fabricated Entirely from Biodegradable and Biocompatible Components

We report the design of slippery liquid-infused porous surfaces (SLIPS) fabricated from building blocks that are biodegradable, edible, or generally regarded to be biocompatible. Our approach involves infusion of lubricating oils, including food oils, into nanofiber-based mats fabricated by electrospinning or blow spinning of poly(ε-caprolactone), a hydrophobic biodegradable polymer used widely in medical implants and drug delivery devices. This approach leads to durable and biodegradable SLIPS that prevent fouling by liquids and other materials, including microbial pathogens, on objects of arbitrary shape, size, and topography. This degradable polymer approach also provides practical means to design "controlled-release" SLIPS that release molecular cargo at rates that can be manipulated by the properties of the infused oils (e.g., viscosity or chemical structure). Together, our results provide new designs and introduce useful properties and behaviors to antifouling SLIPS, address important issues related to biocompatibility and environmental persistence, and thus advance new potential applications, including the use of slippery materials for food packaging, industrial and marine coatings, and biomedical implants.

A Self-defense Hierarchical Antibacterial Surface with Inherent Antifouling and Bacteria-activated Bactericidal Properties for Infection Resistance

Biomedical device-associated infection (BAI) is one of the main reasons for the function failure of implants in clinic practices. Development of high-efficiency antibacterial materials is of great significance to reduce...