A multifunctional upconversion nanoparticles probe for Cu^(2+)sensing and pattern recognition of biothiols

Lanthanide-doped upconversion nanoparticles(Ln-UCNPs)are a new type of nanomaterials with excellent fluorescence properties,which are well applied in fluorescent biosensing.Herein we developed a multifunctional probe based on the surface engineering of core-shell structure UCNPs with polyacrylic acid(PAA).The developed PAA/UCNPs probe could be highly selective to detect and respond to Cu^(2+) at different pH.Cu^(2+) could easily combine with the carboxylate anion of PAA to quench the fluorescence of UCNPs.Therefore,we creatively proposed a fluorescent array sensor(PAA/UCNPs-Cu^(2+)),in which the same material acted as the sensing element by coupled with pH regulation for pattern recognition of 5 thiols.It could also easily identify the chiral enantiomer of cystine(L-Cys-and D-Cys),and distinguish their mixed samples with different concentrations,and more importantly,it could be combined with urine samples to detect actual level of homocysteine(Hcys)to provide a new solution for judging whether the human body suffers from homocystinuria.