Polydopamine nanodots are viable probes for fluorometric determination of the activity of alkaline phosphatase via the in situ regulation of a redox reaction triggered by the enzyme
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The authors describe an environmentally friendly and fast (~14 min) method for the synthesis of homogeneously distributed fluorescent polydopamine nanodots (PDA-NDs) using KMnO4 as the oxidant. Alkaline phosphatase (ALP) catalyzes the hydrolysis of ascorbic acid 2-phosphate to release free ascorbic acid which undergoes an in-situ redox reaction with KMnO4. Depending on the activity of ALP, more or less KMnO4 is consumed, and this affects the formation of the PDA-NDs. Based on this finding, a sensitive method was worked out to quantify the activity of ALP via real-time formation of fluorescent PDA-NDs. The fluorometric signal (best measured at excitation/emission peaks of 390/500 nm) is linear in the 1 to 50 mU·mL−1 ALP activity range, and the limit of the detection is as low as 0.94 mU·mL−1 (based on 3 σ/m). The method was successfully applied to the determination of ALP activity in spiked human serum and in MCF-7 cell lysates. It was also applied in a method to screen for inhibitors of ALP.
KeywordsPolymer quantum dots Fluorescent polymer Ascorbic acid 2-phosphate Bioassay Cell lysates Inhibitor screening
This work was financially supported from the National Natural Science Foundation of China (21605050) and Shanghai Natural Science Foundation (15ZR1411600).
Compliance with ethical standards
The author(s) declare that they have no competing interests.
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