title: Synthesis of functionalized fluorescent gold nanoclusters for acid phosphatase sensing.
abstract: A novel and convenient one-pot but two-step synthesis of fluorescent gold nanoclusters, incorporating glutathione (GSH) and 11-mercaptoundecanoic acid (MUA) as the functionalized ligands (i.e. AuNCs@GSH/MUA), is demonstrated. Herein, the mixing of HAuCl4 and GSH in aqueous solution results in the immediate formation of non-fluorescent GSH-Au(+) complexes, and then a class of ∼2.6 nm GSH-coated AuNCs (AuNCs@GSH) with mild orange-yellow fluorescence after several days. Interestingly, the intense orange-red emitting ∼1.7 nm AuNCs@GSH/MUA can be synthesized within seconds by introducing an alkaline aqueous solution of MUA into the GSH-Au(+) complexes or AuNC@GSH solution. Subsequently, a reliable AuNC@GSH/MUA-based real-time assay of acid phosphatase (ACP) is established for the first time, inspired by the selective coordination of Fe(3+) with surface ligands of AuNCs, the higher binding affinity between the pyrophosphate ion (PPi) and Fe(3+), and the hydrolysis of PPi into orthophosphate by ACP. Our fluorescent chemosensor can also be applied to assay ACP in a real biological sample and, furthermore, to screen the inhibitor of ACP. This report paves a new avenue for synthesizing AuNCs based on either the bottom-up reduction or top-down etching method, establishing real-time fluorescence assays for ACP by means of PPi as the substrate, and further exploring the sensing applications of fluorescent AuNCs.
authors.affiliation: State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China. xryang@ciac.ac.cn.
authors.forename: Jian
authors.initials: J
authors.lastname: Sun
authors.forename: Fan
authors.initials: F
authors.lastname: Yang
authors.forename: Xiurong
authors.initials: X
authors.lastname: Yang
mesh_terms: D000135:Acid Phosphatase / Q000032:analysis*; D000818:Animals; D015374:Biosensing Techniques / Q000379:methods*; D002417:Cattle; D005453:Fluorescence; D006046:Gold / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*
chemical_list: D006046:Gold; D000135:Acid Phosphatase