title: A convenient and label-free fluorescence "turn off-on" nanosensor with high sensitivity and selectivity for acid phosphatase.
abstract: In this study, we reported a convenient label-free fluorescence nanosensor for rapid detection of acid phosphatase on the basis of aggregation-caused quenching (ACQ) and enzymolysis approach. The selectivity nanosensor was based on the fluorescence "turn off-on" mode, which possessed high sensitivity features. The original strong fluorescence intensity of CuInS2 QDs was quenched by sodium hexametaphosphate (NaPO3)6. The high efficiency of the quenching was caused by the non-covalent binding of positively charged CuInS2 QDs to the negatively charged (NaPO3)6 through electrostatic interactions, aggregating to form a CuInS2 QDs/(NaPO3)6 complex. Adding acid phosphatase caused intense fluorescence of CuInS2 QDs/(NaPO3)6 to be recovered, and this was because of enzymolysis. (NaPO3)6 was hydrolyzed into small fragments and the high negative charge density decreased, which would weaken the strong electrostatic interactions. As a result, the quenched fluorescence "turned on". Under the optimum conditions, there was a good linear relationship between I/I0 (I and I0 were the fluorescence intensity of CuInS2 QDs/(NaPO3)6 system in the presence and absence of acid phosphatase, respectively) and acid phosphatase concentration in the range of 75-1500 nU mL(-1) with the detection limit of 9.02 nU mL(-1). The proposed nanosensor had been utilized to detect and accurately quantify acid phosphatase in human serum samples with satisfactory results.
authors.affiliation: Department of Analytical Chemistry, College of Chemistry, Jilin University, Changchun 130012, China.
authors.forename: Ziping
authors.initials: Z
authors.lastname: Liu
authors.affiliation: Department of Analytical Chemistry, College of Chemistry, Jilin University, Changchun 130012, China.
authors.forename: Zihan
authors.initials: Z
authors.lastname: Lin
authors.affiliation: Department of Analytical Chemistry, College of Chemistry, Jilin University, Changchun 130012, China.
authors.forename: Linlin
authors.initials: L
authors.lastname: Liu
authors.affiliation: Department of Analytical Chemistry, College of Chemistry, Jilin University, Changchun 130012, China. Electronic address: suxg@jlu.edu.cn.
authors.forename: Xingguang
authors.initials: X
authors.lastname: Su
mesh_terms: D000135:Acid Phosphatase / Q000097:blood* / Q000378:metabolism; D057075:Enzyme Assays / Q000379:methods; D005453:Fluorescence; D005456:Fluorescent Dyes; D006801:Humans; D057230:Limit of Detection; D010710:Phosphates / Q000378:metabolism*; D045663:Quantum Dots / Q000378:metabolism* / Q000648:ultrastructure; D013050:Spectrometry, Fluorescence / Q000379:methods
chemical_list: D005456:Fluorescent Dyes; D010710:Phosphates; D000135:Acid Phosphatase; C009285:sodium polymetaphosphate
keywords: (NaPO(3))(6); Acid phosphatase; Aggregation-caused quenching and enzymolysis; CuInS(2) QDs; Fluorescence “turn off–on” nanosensor