In this study, we developed a reflective localized surface plasmon resonance (LSPR) optical fiber sensor, based on silver nanoparticles (Ag NPs). To enhance the sensitivity of the LSPR optical sensor, two key parameters were optimized, the length of the sensing area and the coating time of the Ag NPs. A sensing length of 1.5 cm and a 1-h coating time proved to be suitable conditions to produce highly sensitive sensors for biosensing. The optimized sensor has a high refractive index sensitivity of 387 nm/RIU, which is much higher than that of other reported individual silver nanoparticles in solutions. Moreover, the sensor was further modified with antigen to act as a biosensor. Distinctive wavelength shifts were found after each surface modification step. In addition, the reflective LSPR optical fiber sensor has high reproducibility and stability.

In this study, a peptide-based artificial hydrolase with photo-switchable activity was fabricated by the introduction of a catalytic histidine residue and a photo-responsive azobenzene group into the peptide chain. The peptide exhibits a structural transition from an antiparallel β-sheet to a random coil upon photo-irradiation, leading to the assembly/disassembly of the peptide fibril. An enhanced catalytic activity on p-nitrophenyl acetate was observed due to the proximity effect of the histidine residues and the hydrophobic microenvironment in the supramolecular assemblies. Under UV irradiation, this supramolecular system was destroyed together with a decline in the catalytic activity. Based on these photo-responsive properties, the activity of the hydrolase mimic can be reversibly controlled using UV and visible light. This study provides a new approach for constructing a switchable artificial enzyme based on a peptide material platform.

In this study, a facile one-step synthesis of a novel nanocomposite catalytic film was developed based on silver nanoparticles (AgNPs) immobilized in tannic acid-modified eggshell membrane (Tan-ESM). Tannic acid, as a typical plant polyphenol from oak wood, was first grafted onto ESM fibers to serve as both the reductant and the stabilizer during the synthesis of AgNPs. The morphology, constitution, and thermal stability of the resulting AgNPs@Tan-ESM composites were fully characterized to explain the excellent catalytic efficiency of AgNPs@Tan-ESM composites. These composite catalysts were applied to the degradation of azo dyes which exhibited the high catalytic activity toward Congo red and methyl orange according to the kinetic curves. More importantly, they can be easily recovered and reused for many times because of their good stability.