Synthesis of PEG hydrogel with dityrosine for multi-functionality and pH-dependent fluorescence

Minimalist Design for a Hand-Held SARS-Cov-2 Sensor: Peptide-Induced Covalent Assembly of Hydrogel Enabling Facile Fiber-Optic Detection of a Virus Marker Protein

The rampaging COVID-19 needs bioassaying methods of low cost and high robustness for those living in the poorly developed regions. Here, we propose such a method that does not need expensive and complicated equipment. Only a set of hand-held small devices is sufficient. A section along an optic fiber cable is stripped, so that laser light travelling through it will leak outside, while biosensing process taken place on this stripped section can form a new cladding layer of hydrogel, restoring the laser output of the fiber. A short peptide probe immobilized on the stripped section of the fiber can covalently capture a biomarker protein of SARS-Cov-2 from the serum sample. Through the cross-linking of the target protein with the interfering proteins in the serum sample, a hydrogel is covalently immobilized around the stripped section, highly resistant to detergent rinsing that is indispensable for removing nonspecific interference from the clinical sample. Using this "covalent biosensing" strategy, only one peptide probe is sufficient to simultaneously achieve ultrahigh affinity toward the biomarker protein of SARS-Cov-2 and effective signal amplification.

Fluorescent carbon nanoparticles derived from natural materials of mango fruit for bio-imaging probes

Water soluble fluorescent carbon nanoparticles (FCP) obtained from a single natural source, mango fruit, were developed as unique materials for non-toxic bio-imaging with different colors and particle sizes. The prepared FCPs showed blue (FCP-B), green (FCP-G) and yellow (FCP-Y) fluorescence, derived by the controlled carbonization method. The FCPs demonstrated hydrodynamic diameters of 5-15 nm, holding great promise for clinical applications. The biocompatible FCPs demonstrated great potential in biological fields through the results of in vitro imaging and in vivo biodistribution. Using intravenously administered FCPs with different colored particles, we precisely defined the clearance and biodistribution, showing rapid and efficient urinary excretion for safe elimination from the body. These findings therefore suggest the promising possibility of using natural sources for producing fluorescent materials.