The incorporation of fluorescent nanoprobes into three dimensional (3D) matrixes is capable of enhancing the fluorescence properties of nanoprobes and greatly benefiting sensing application. In this work, N-acetyl-l-cysteine capped-copper nanoclusters (NAC-CuNCs) were incorporated into 3D mesoporous silica particles (M-SiO2) through electrostatic assembly. The assembly process takes only 2 min, and the fluorescence emission and quantum yield of NAC-CuNCs were significantly improved owing to the electrostatic confinement effect of M-SiO2. The prepared M-SiO2@NAC-CuNCs was further integrated with MnO2 nanosheets, a newly-emerged fluorescence nanoquencher with broad absorption spectrum. The emission intensity of M-SiO2@NAC-CuNCs was significantly decreased in the presence of MnO2 nanosheets by inner filter effect (IFE), and then recovered by ascorbic acid generated by the enzymolysis of l-ascorbic acid-2-phosphate (AAP) in the presence of acid phosphatase (ACP). On this basis, an enhanced emission platform was developed for "turn off-on" detection of ACP, a key indicator for diagnosis of prostate cancer. The detection limit for ACP activity was 0.47 U/L. Moreover, the approach was used to monitor ACP level in real serum samples with high accuracy, providing an attractive approach for clinical diagnosis of prostate cancer and other ACP-related diseases.
Keywords: Acid phosphatase detection; Copper nanoclusters; Electrostatic confinement effect; Mesoporous silica particles.
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