Gold nanoclusters-based chemiluminescence resonance energy transfer method for sensitive and label-free detection of trypsin

• Au NCs-based CRET platform was developed for detection of trypsin.
• BSA-stabilized Au NCs were used as energy acceptor.
• Trypsin significantly decreased the CL signal via digesting BSA-stabilized Au NCs.
• The assay is simple, sensitive and label-free.
• The determination of trypsin in human urine was demonstrated.

A chemiluminescence resonance energy transfer (CRET) platform was developed for sensitive and label-free detection of protease by using trypsin as a model analyte. In this CRET platform, bis(2,4,6-trichlorophenyl)oxalate–hydrogen peroxide chemiluminescence (CL) reaction was utilized as an energy donor and bovine serum albumin (BSA)-stabilized gold nanoclusters (Au NCs) as an energy acceptor. The BSA-stabilized Au NCs triggered the CRET phenomenon by accepting the energy from TCPO-H2O2 CL reaction, thus producing intense CL. In the presence of trypsin, the protein template of BSA-stabilized Au NCs was digested, which frustrated the energy transfer efficiency between the CL donor and the BSA-stabilized Au NCs, leading to a significant decrease in the CL signal. The decreased CL signal was proportional to the logarithm of trypsin concentration in the range of 0.01–50.0 µg mL−1. The detection limit for trypsin was 9 ng mL−1 and the relative standard deviations were lesser than 3% (n=11). This Au NCs-based CRET platform was successfully applied to the determination of trypsin in human urine samples, demonstrating its potential application in clinical diagnosis.

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