Bioinspired Slippery Lubricant-Infused Surfaces With External Stimuli Responsive Wettability: A Mini Review.

Responsive slippery lubricant-infused surfaces (SLIS) have attracted substantial attention because of the high demand of fundamental research and practical applications, such as controllable liquid-repellency, intelligent, and easy-to-implement wettability switching. In this review, advanced development of responsive slippery surfaces is briefly summarized upon various external stimuli, including stress, electrical field, magnetic field, and temperature. In addition, remaining challenge and prospect are also discussed.

Visual detection of the prostate specific antigen via a sandwich immunoassay and by using a superwettable chip coated with pH-responsive silica nanoparticles.

A pH-responsive superwettable chip is described whose surface can switch between superhydrophobic and superhydrophilic. It can be used for the visual detection of the prostate specific antigen (PSA) based on contact angle readout. Magnetic beads were modified with primary antibody against PSA. After immunobinding, gold nanoparticles loaded with secondary antibody labeled with glucose oxidase is added. On addition of glucose, gluconic acid is formed which causes a drop in the local pH value. This results in a wettability switch of the pH-responsive superwettable chip from hydrophobic to hydrophilic. Under the optimized conditions, PSA can be quantified with a 3.2 pg mL-1 limit of detection by analyzing the contact angle and the related color that changes from blue via orange to red. The method is applicable to PSA detection in serum samples and for visual classification by cancer patients and healthy persons. It is also suitable for color-blind and color-weak individuals. Conceivably, this kind of assay can be transferred to the determination of various kinds of other bioanalytes including nucleotide, proteins, and even of ions and small organic molecules, and thus is has a wide scope. Graphical abstract Schematic presentation of a pH-responsive superwettable chip coated with silica nanoparticles for the visual detection of prostate specific antigen (PSA) by reading the contact angle. The superwettable chip achieves reliable clinical detection of serum PSA from prostate cancer patients.

Turn-on fluorescent sensor for the detection of glucose using manganese dioxide-phenol formaldehyde resin nanocomposite.

Monitoring blood glucose has attracted considerable attention because diabetes mellitus is a global public health problem. Herein, we reported a turn-on fluorescence detection strategy based on manganese dioxide (MnO2)-phenol formaldehyde resin (PFR) nanocomposite for rapid, sensitive, and selective detection of glucose levels in human blood. In this biosensing system, MnO2 nanoshell on the PFR nanoparticle surfaces serve as a quencher. PFR fluorescence can make a recovery in the presence of H2O2, reducing MnO2 to Mn2+. The sensor shows a linear range from 50nM to 90µM with a low detection limit of 20nM for H2O2 detection. Thus, the glucose can be detected on the basis of the enzymatic conversion of glucose by glucose oxidase to produce H2O2. This method exhibits a wide linear range from 5µM to 1mM with a low detection limit of 1.5µM. Because of the excellent photostability offered by PFR, the developed strategy has been successfully applied for the diagnosis of diabetes mellitus in human blood samples. Compared with commercial glucometer, our method showed satisfactory results, indicating the significant reliability. The developed turn-on fluorescent sensor might hold great promise in nanomedicine and bioanalysis.