Boc-L-glutamine N-hydrosuccinimide ester

The use of furazolidone in food animals has been banned in European Union (EU) because of its carcinogenicity and mutagenicity on human health, but its continued misuse is widespread. Therefore, there is an urgent need for a simple, reliable, and rapid method for the detection of its marker residue, 3-amino-2-oxazolidinone (AOZ), in food products. In this regard, a sensitive and reliable electrochemical method was presented to detect AOZ based on a novel label-free electrochemical impedimetric immunosensor to address this need. The immobilization of monoclonal antibody against AOZ (denoted as AOZ-McAb) on the gold electrode was carried out through a stable acyl amino ester intermediate generated by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydrosuccinimide (NHS), which could condense antibodies on the self-assembled monolayer (SAM). The detection of AOZ was performed by measuring the relative change in charge transfer resistance before and after AOZ and AOZ-McAb immunoreaction by electrochemical impedance spectroscopy (EIS). Under the optimized conditions, the relative change in charge transfer resistance was proportional to the logarithmic value of AOZ concentrations in the range of 20.0 to 1.0×10(4) ng mL(-1) (r=0.9987). Moreover, the proposed immunosensor has a high selectivity to AOZ alone with no significant response to the metabolites of other nitrofuran antibiotics, such as 3-amino-5-morpholinomethyl-2-oxazolidinone (AMOZ), semicarbazide (SEM), and 1-aminohydantoin hydrochloride (AHD). This protocol has been applied to detect AOZ in food samples with satisfactory results.

Hydrogel-based electronics have found widespread applications in soft sensing and health monitoring because of their remarkable biocompatibility and mechanical features similar to human skin. However, they are subjected to potential challenges like structural failure, functional degradation, and device delamination in practical applications, especially facing extreme environmental conditions (e.g., abnormal temperature and humidity). To address these, ionically conductive organohydrogel-based soft electronics are developed, which can perform at subzero and elevated temperatures (thermal compatibility) as well as at dehydrated and hydrated environments (hydration compatibility) for extended applications. More specifically, gelatin/poly(acrylic acid-N-hydrosuccinimide ester) (PAA-NHS ester)-based ionic-conductive organohydrogel is synthesized. By introducing a glycerol-water binary solvent system, the gel can maintain mechanical softness in a wide temperature range (from -80 to 60 °C). Besides, excellent conductivity is achieved under various conditions by soaking the gel into lithium chloride anhydrous (LiCl) solution. Strong adhesion with skin, even under water, can be realized by covalent bonds between NHS ester from gel and amino groups from human skin. The excellent performances of LiCl-loaded PAA-based organohydrogel (L-PAA-OH)-based electronics are further demonstrated under freezing and high temperatures as well as underwater conditions, unveiling their promising prospects in wearable health monitoring in various conditions.

Two dry surfaces can instantly adhere upon contact with each other through intermolecular forces such as hydrogen bonds, electrostatic interactions and van der Waals interactions1,2. However, such instant adhesion is challenging when wet surfaces such as body tissues are involved, because water separates the molecules of the two surfaces, preventing interactions3,4. Although tissue adhesives have potential advantages over suturing or stapling5,6, existing liquid or hydrogel tissue adhesives suffer from several limitations: weak bonding, low biological compatibility, poor mechanical match with tissues, and slow adhesion formation5-13. Here we propose an alternative tissue adhesive in the form of a dry double-sided tape (DST) made from a combination of a biopolymer (gelatin or chitosan) and crosslinked poly(acrylic acid) grafted with N-hydrosuccinimide ester. The adhesion mechanism of this DST relies on the removal of interfacial water from the tissue surface, resulting in fast temporary crosslinking to the surface. Subsequent covalent crosslinking with amine groups on the tissue surface further improves the adhesion stability and strength of the DST. In vitro mouse, in vivo rat and ex vivo porcine models show that the DST can achieve strong adhesion between diverse wet dynamic tissues and engineering solids within five seconds. The DST may be useful as a tissue adhesive and sealant, and in adhering wearable and implantable devices to wet tissues.