Superwettable interface towards biodetection in confined space

The detection of biomarkers with both high sensitivity and specificity is crucial for the diagnosis and treatment of related diseases.However,many current detections employ ex-situ detection method and non-confined condition,thus have many problems,which may eventually lead to inaccurate detection results.Compared to detection in non-confined space,detection in confined space can better reflect the real in-vivo situation.Therefore,the construction of detection for target molecules in confined space has great significance for both theoretical research and practical application.To realize the detection of target molecules in confined space,the probes should accurately enter the confined space where the target molecules reside and interact with the interface.Thus,how to explore and utilize the properties of the interface(for example,bioinspired superwettability)has always been a hot and difficult topic in this field.Herein,the recent advances and our efforts in recent 10 years on detection of bio-target molecules in confined space with superwettable interface have been introduced from the perspective of the detection methods.The suitable and most widely employed detection methods for target molecules in confined spaces are introduced firstly.Then,recent progresses for related detections based on visual,optical,and electrochemical detection methods are presented successively.Finally,the perspective for detection in confined space is discussed for the future development of biochemical detection.

Polydopamine-Based Colorimetric Superwettable Biosensor for Highly Sensitive Detection of Hydrogen Peroxide and Glucose

Superwettable surface has broad application prospects in fabricating biosensors due to its significant enrichment effect.Here,we report a polydopamine-based colorimetric superwettable sensor that integrates superhydrophobic-superhydrophilic micropatterns for the determination of hydrogen peroxide(H_(2)O_(2))and glucose.Dopamine can be oxidized into polydopamine with the addition of horseradish peroxidase(HRP)and H_(2)O_(2),leading to the deposited spots color change from colorless to black.The concentration of target can be determined by analyzing RGB value using a smartphone software.The superhydrophobic area on the superwettable surface helps capture droplets by confining them to superhydrophilic microwells.After droplet evaporation,the analytes are concentrated in the small superhydrophilic domain,thus greatly enhancing the sensitivity.The experimental results manifested that superwettable sensor is able to detect H_(2)O_(2)with a broad linear range of 0.25μmol/L-25 mmol/L and a low limit of detection(LOD)of 0.25μmol/L by naked eye.For glucose detection,the linear range of the sensor is from 2μmol/L to 20 mmol/L and LOD is 0.69μmol/L.The superwettable sensor has been successfully applied in practical samples,including cancerous cells,milk,urine,and human serum samples with acceptable results.This superwettable sensor has several merits,such as high sensitivity,rapid response,and low sample volume in a single microdroplet,and shows great potential in manufacturing portable devices for complex biosensing applications.

Stable Superwetting Surface Prepared with Tilted Silicon Nanowires

Large-scale uniform nanostructured surface with superwettability is crucial in both fundamental research and engineering applications.A facile and controllable approach was employed to fabricate a superwetting tilted silicon nanowires(TSNWs) surface through metal-assisted chemical etching and modification with low-surface-energy material.The contact angle(CA) measurements of the nanostructured surface show a large range from the superhydrophilicity(the CA approximate to 0°) to superhydrophobicity(the CA up to 160°).The surface becomes antiadhesion to water upon nanostructuring with a measured sliding angle(a) close to 0°.Moreover,the fluorinated TSNWs surface exhibits excellent stability and durability because strong chemical bonding has been formed on the surface.

Underoil superhydrophilic flame-retardant 3D porous composite for efficient on-demand emulsion separation:Interface engineering design on sphagnum moss

Oil pollution and the energy crisis make oil-water separation an urgent for human need.The widespread use of materials with a single emulsion separation capability is limited.Multifunctional on-demand separation materials can adapt to a wide range of application scenarios,thus having a wider range of applications.The underoil superhydrophilic surface is of great significance for realizing the on-demand separation of oil/water emulsions through the removal of water in the oil and oil in the water.A 3D porous emulsion separation material based on the superhydrophilic principle of sphagnum moss was designed.The material was prepared in a simple step by taking advantage of the adhesion of polydopamine and the introduction of the as-prepared superhydrophilic BaSO4 nanoparticles to achieve superhydrophilicity with a water contact angle(WCA)of 0°and an oil contact angle(OCA)of 157.3°,resulting in excellent separation performance for both water-in-oil and oil-in-water emulsions.Underoil superhydrophilic porous composite(OSPC)can complete two kinds of emulsion separations by filtration or adsorption.It adsorbs water from water-in-oil emulsion to achieve separation,with a good adsorption capacity of 74.38 g/g and efficiency up to 99%.It can also filter oil-in-water emulsions with an efficiency of 99.92%.The separation efficiencies are all almost unchanged after ten separation cycles.Furthermore,the material has excellent flame retardancy,which reduces the possibility of secondary disasters.The three-dimensional porous sponge has excellent on-demand separation performance for multiple emulsions.It provides a new preparation strategy for underoil superhydrophilic materials and a new idea for the design direction of special wetting materials for the on-demand separation of oil/water emulsions.

Bioinspired Stable Single‑Layer Janus Fabric with Directional Water/Moisture Transport Property for Integrated Personal Cooling Management

Extensive progress has been achieved regarding Janus fabric for directional water transport due to its excellent and feasible personal cooling management ability,which has great significance for energy conservation,pollution reduction,and human health.However,existing Janus asymmetric multilayer fabrics for directional water transport are still limited by their com-plicated syntheses and poor stabilities.Inspired by the compositionally graded architecture of leaf cuticles,we propose a single-layer Janus personal cooling management fabric(JPCMF)via a one-step electrospinning method.The JPCMF shows not only great directional bulk water transport ability but also asymmetry moisture(water vapor)transport ability with a high asymmetry factor(1.49),water vapor transmission value(18.5 kg^(-1) m-2 D-1),and water evaporation rate(0.735 g h^(-1)).Importantly,the JPCMF exhibits outstanding durability and stability thanks to a novel electrostatic adsorption-assisted self-adhesion strategy for resisting abrasion,peeling and pulling.With these characteristics,the JPCMF can achieve a 4.0°C personal cooling management effect,better than taht of cotton fabric,on wet skin.The good biocompatibility and nontoxic-ity also endow the JPCMF with the potential to be a self-pumping dressing.Our strategy should facilitate a new method for developing next-generation intelligent multifunctional fabrics.

Fast processing nylon mesh by surface diffuse atmospheric plasma for large-area oil/water separation

In recent years,numerous studies have been reported for oil/water separation,such as superoleophilic materials for oil absorption and underwater superoleophobic membranes for continuous separation.However,for the recovery of oil slick pollution on near-shore ocean surface caused by various reasons,large area and fast availability of used materials are needed to be considered.Herein,we report an efficient and environmentally friendly method to fast process nylon mesh by surface diffuse atmospheric plasma(SDAP)for large-area oil/water separation.Nylon mesh is funcionalized by atmospheric plasma to generate micro/nano composite structures on the surface,resulting in superhydrophilicity and underwater superoleophobicity within only seconds.The pre-wetted modified nylon mesh can achieve high efficiency(>99.9%)and circulating water flux(~30,000 L·m^(-2)·h^(-1)),with high intrusion pressure(~3 kPa)and universality in oil/water separation.Regular plasma unconditionally generated in the atmosphere with the merit of efficiently functionalizing surface has the potential of large-area materials treatment.This study might take one step further for large-area industrial oily wastewater recovery and even oil slicks collection in near-shore water bodies.

Understanding the Separations of Oil/Water Mixtures from Immiscible to Emulsions on Super-wettable Surfaces

As the frequent oil spill accidents happens and large quantities of oily wastewater from all kinds of industries are being discharged, the environment has been seriously polluted and our living areas have been horribly threatened. To deal with these issues, attentions have been aroused on the treatments of the oily wastewater. Recently, numerous superwettable materials have been fabricated. In this review, we summarize the new development of the materials for the separation of oil/water mixtures, mainly including the immiscible and emulsified mixtures. For the separation of immiscible ones, special materials with fixed wettability are firstly detailed, where three types of materials can be classified based on their wettability, i.e. superhydrophobic and superoleophilic materials, superhydrophilic and underwater superoleophobic materials, and superhydrophilic and su- peroleophobic materials. Then, the smart materials with switchable wettabilities responsive to external stimulus, for instance, light, solvent, pH, temperature, and electrical potential, are presented. Meanwhile, the single, dual, and multiple stimu- lus-responsive materials are also described. As for the separation of emulsified oil/water mixtures, the materials for the sepa- ration of water-in-oil （W/O）, oil-in-water （O/W）, and both water-in-oil （W/O） and oil-in-water （O/W） emulsions are sequen- tially introduced. Finally, some challenges are discussed and the outlook in this filed is proposed.

Namib desert beetle inspired special patterned fabric with programmable and gradient wettability for efficient fog harvesting

Efficient collection of water from fog provides a potential solution to solve the global freshwater shortage problem, particularly in the desert or arid regions. In this work, a flexible and highly efficient fog collector was prepared by mimicking the back exoskeleton structure of the Namib desert beetle. The improved fog collector was constructed by a superhydrophobic-superhydrophilic patterned fabric via a simple weaving method, followed by in-situ deposition of copper particles. Compared with the conventional fog collector with a plane structure, the fabric has shown a higher water-harvesting rate at 1432.7 mg/h/cm2,owing to the biomimetic three-dimensional structure, its enhanced condensation performance enabled by the copper coating and the rational distribution of wetting units. The device construction makes use of the widely available textile materials through mature manufacturing technology, which makes it highly suitable for large-scale industrial production.

Bioinspired membranes for multi-phase liquid and molecule separation

Water pollution is a serious problem around the world. It causes the lack of clean drinking water and brings risks to human health.Membrane technology has become a competitive candidate to treat the contaminated wastewater due to its high separation efficiency and low energy consumption. In this review, we introduce the recent development of several kinds of bioinspired separation membranes, involving the membrane design and applications. We emphasize the multi-phase liquid separation membranes inspired from nature with special wettability applied for oil/water separation, organic liquids mixture separation, and emulsion separation. After separating multi-phase liquids using these membranes, small molecule pollutants still exist in singlephase liquid. Therefore, we also expand the scope to small molecule-scale separation membranes, such as the nacre-like graphene oxide separation membrane and other nanofiltration membranes. Summary and outlook concerning the future development of separation membranes are also introduced briefly.

Bio-inspired manufacturing of superwetting surfaces for fog collection and anti-icing applications

As a century-old concept,superwettability has aroused the interest of researchers in the past decades,attributed to the discoveries of the mechanisms of special wetting phenomena in nature.Bio-inspired manufacturing of superwetting surfaces for fog collection and anti-icing applications has become mainstream research,potentially alleviating the problem of water shortage and ice accidents.Superwetting surfaces for fog collection and anti-icing applications involve a reverse process,in which the former gathers water spontaneously,while the latter repels water.Contrastive analysis of the two is essential for the comprehensive understanding of superhydrophilic/superhydrophobic surfaces and boosting their applications.Herein,wetting theories and basic mechanisms for fog collection and anti-icing are briefly introduced.Then,manufacturing methods of bionic structures and surfaces are systematically reviewed after discussing the typical organisms with superwettability.Finally,conclusions are drawn and prospects for future development are proposed.