Synthesis of carboxyl-capped and bright YVO4:Eu,Bi nanoparticles and their applications in immunochromatographic test strip assay

Graphical abstract: - Highlights: • The morphology and properties of YVO{sub 4}:Eu,Bi nanoparticles were investigated. • YVO{sub 4}:Eu,Bi were coupled with IgG for bioprobes due to their good properties. • YVO{sub 4}:Eu,Bi were applied to immunochromatographic test strip assay. - Abstract: Carboxyl-capped YVO{sub 4}:Eu,Bi nanoparticles with average diameter of ∼10 nm were synthesized via a copolymer of phosphono and carboxylic acid mediated hydrothermal method. Under a 350 nm ultraviolet light excitation, the YVO{sub 4}:Eu,Bi NPs exhibit sharp and bright red emission peaked at 615 nm and with highest quantum yield of ∼43%. Furthermore, the nanoparticles show good water/buffer stability and feasible bioconjugation benefiting from the carboxylic groups on their surface. Based on these kind optical and surface properties of the YVO{sub 4}:Eu,Bi nanoparticles, an immunochromatographic test strip assay for quantitative determination of human IgG was achieved. This protocol can be extended to other rare-earth nanoparticles with the purpose of developing bioprobes for desired applications.