β-NaYFa：Yb,Er upconversion nanophosphor （UCNP） is known as one of the most efficient NIR-to-visible upconversion mate- dais, which shows great potential in bioanalytical chemistry and bioimaging. However, its appl...β-NaYFa：Yb,Er upconversion nanophosphor （UCNP） is known as one of the most efficient NIR-to-visible upconversion mate- dais, which shows great potential in bioanalytical chemistry and bioimaging. However, its applications are greatly limited due to its low water dispersibility and thus poor biocompatibility. In this paper, poly（acrylic acid） （PAA）-based ligand exchange strategies are carded out to modify oleic acid-capped hydrophobic β-NaYF4：Yb,Er UCNPs into hydrophilic ones. After efficient surface modification, the presence of free carboxylic acid groups on the surfaces of UCNPs results in high solubility in water, and also allows further conjugation with NH2-containing biomolecules. Facilitated by the covalent linkage between the -COOH groups on UCNPs surfaces and -NHz groups in antigen/antibody, a sensitive immunosensor is constructed by using PAA-functionalized β-NaYFa：Yb,Er UCNPs as biolabels. Through monitoring the upconversion fluorescence intensity or fluorescent imaging of the final immunocomplexes, high sensitivity is achieved for the proposed immunoassay and as low as 0.1 ng/mL goat anti-human immunoglobulin G （IgG） can be detected, which suggests that PAA-modified UCNPs may serve as an ideal candidate for use as bioanalysis and bioimaging probes.展开更多
基金supported by the National Natural Science Foundation of China (20925519 & 20875021)the Natural Science Foun-dation of Hebei Province (B2009001525 & B2010000202)the China Postdoctoral Science Foundation (20100470985)
文摘β-NaYFa：Yb,Er upconversion nanophosphor （UCNP） is known as one of the most efficient NIR-to-visible upconversion mate- dais, which shows great potential in bioanalytical chemistry and bioimaging. However, its applications are greatly limited due to its low water dispersibility and thus poor biocompatibility. In this paper, poly（acrylic acid） （PAA）-based ligand exchange strategies are carded out to modify oleic acid-capped hydrophobic β-NaYF4：Yb,Er UCNPs into hydrophilic ones. After efficient surface modification, the presence of free carboxylic acid groups on the surfaces of UCNPs results in high solubility in water, and also allows further conjugation with NH2-containing biomolecules. Facilitated by the covalent linkage between the -COOH groups on UCNPs surfaces and -NHz groups in antigen/antibody, a sensitive immunosensor is constructed by using PAA-functionalized β-NaYFa：Yb,Er UCNPs as biolabels. Through monitoring the upconversion fluorescence intensity or fluorescent imaging of the final immunocomplexes, high sensitivity is achieved for the proposed immunoassay and as low as 0.1 ng/mL goat anti-human immunoglobulin G （IgG） can be detected, which suggests that PAA-modified UCNPs may serve as an ideal candidate for use as bioanalysis and bioimaging probes.
