Luminescent Aggregated Copper Nanoclusters Nanoswitch Controlled by Hydrophobic Interaction for Real-Time Monitoring of Acid Phosphatase Activity

Abstract

A reversible luminescence nanoswitch through competitive hydrophobic interaction among copper nanoclusters, p-nitrophenol and α-cyclodextrin is established, and a reliable real-time luminescent assay for acid phosphatase (ACP) activity is developed on the basis of this luminescence nanoswitch. Stable and intensely luminescent copper nanoclusters (CuNCs) were synthesized via a green one-pot approach. The hydrophobic nature of CuNCs aggregate surface is identified, and further used to drive the adsorption of p-nitrophenol on the surface of CuNCs aggregate due to their hydrophobic interaction. This close contact switches off the luminescence of CuNCs aggregate through static quenching mechanism. However, the introduction of α-cyclodextrin switches on the luminescence since stronger host-guest interaction between α-cyclodextrin and p-nitrophenol causes the removal of p-nitrophenol from the surface of CuNCs. This nanoswitch in response to external stimulus p-nitrophenol or α-cyclodextrin can be run in a reversible way. Luminescence quenching by p-nitrophenol is further utilized to develop ACP assay using p-nitrophenyl phosphate ester as the substrate. Quantitative measurement of ACP level with a low detection limit of 1.3 U/L was achieved based on this specific detection strategy. This work reports a luminescence nanoswitch mediated by hydrophobic interaction, and provides a sensitive detection method for ACP level which is capable for practical detection in human serum and seminal plasma.

Copper nanoclusters: designed synthesis, structural diversity, and multiplatform applications

“…In this regard, Yuanyuan Huang et al prepared a CuNCs-based fluorometric probe to detect the concentration of ACP in human serum and seminal plasma with LOD of 1.3 U/L. 220 Much better analytical performance for ACP detection has been achieved when polydopamine (PDA)-CuNCs were applied as a sensor with LOD value of 1 mU/L. 276…”

Sensitive Naked‐eye and Fluorescence Determination of Acetylcholinesterase Activity using Cu/Ag Nanoclusters Based on Inner Filter Effect

“…This result indicates that Cu/Ag NCs mainly consist of Cu (0) and Cu (1), with Cu (II) absent in the nanoclusters. [28] In Figure 1f, the binding energy of Ag 2p 5/2 and Ag 2p 3/2 in Ag 2p spectrum were at 367.8 eV and 374.0 eV, indicating the coexistence of Ag + and Ag 0 . [29]…”

Ligand functionalized copper nanoclusters for versatile applications in catalysis, sensing, bioimaging, and optoelectronics

“…The same PL-off or PL-on switching mechanism was used for the real-time monitoring of acid phosphatase activity, in which after hydrolyzing the bond between 4-nitrophenol and the phosphate group in p-nitrophenyl phosphate disodium, the PL quenching occurred. 251 In another study, 67 the acid phosphatase (ACP) enzyme activity was measured by redox-responsive emission of Cu NC aggregates. It was shown that D-penicillamine-capped Cu NCs with pH and temperature responsiveness could aggregate to form particles with stronger red luminescence.…”