Preparation of PEG and protein co-immobilized upconversion nanophosphors as near-infrared biolabeling materials

Upconversion phosphors are expected to be used as fluorescence biolabeling materials. One of upconversion phosphors, erbium ion-doped-Y2O3 (Y2O3: Er) nanoparticles (YNPs) was synthesized by homogeneous precipitation method. Poly(ethylene glycol)-b-Poly(acrylic acid) (PEG-b-PAAc) was immobilized on the surface of YNP to improve dispersing stability and prevention of nonspecific adsorption. In order to install protein on the YNP surface, co-immobilization of PEG-b-PAAc and bovine serum albumin (BSA) as a model protein was carried out. The specific molecular recognition of PEG/BSA co-immobilized YNPs (PEG/BSA-YNPs) was confirmed by anti-BSA antibody plate assay. The obtained complex is a promising near-infrared biolabeling materials with high performances.