Related Experiment Video
Updated: Feb 6, 2026

Synthesis of Near-Infrared Emitting Gold Nanoclusters for Biological Applications
Published on: March 22, 2020
A fluorometric sensing method for sensitive detection of trypsin and its inhibitor based on gold nanoclusters and
Mengke Wang1, Dandan Su1, Guannan Wang2
1Department of Analytical Chemistry, College of Chemistry, Jilin University, Changchun, 130012, Jilin, China.
Abstract:
In this work, a facile, label-free, and sensitive fluorometric strategy for detection of trypsin and its inhibitor was established on the basis of the fluorescence resonance energy transfer (FRET) between mercaptoundecanoic acid functionalized gold nanoclusters (AuNCs) and gold nanoparticles (AuNPs) via protamine as a bridge. Protamine can trigger the aggregation of AuNPs and link AuNCs with aggregated AuNPs through electrostatic interaction. Compared with monodisperse AuNPs, the UV-vis absorption band of aggregated AuNPs overlapped considerably with the emission spectrum of AuNCs. Thus, the fluorescence of AuNCs was obviously quenched by the aggregated AuNPs through FRET. In the presence of trypsin, protamine was hydrolyzed into small fragments, leading to the deaggregation of AuNPs and breaking of the short distance between AuNPs and AuNCs, so the FRET process was inhibited, and the fluorescence of AuNCs was recovered. The increase in the fluorescence intensity of AuNCs was directly related to the amount of trypsin. Hence trypsin can be determined on the basis of the variation of fluorescence intensity, with a linear range of 5-5000 ng mL-1 and a detection limit of 1.9 ng mL-1. In addition, this system was used for the detection of trypsin inhibitor by application of the inhibitor isolated from soybean as a model. The sensing method was applied for trypsin detection in human urine and commercial multienzyme tablet samples with satisfactory results. Graphical abstract ᅟ.
Related Concept Videos
The Sense of Self: Reflected Self-Appraisal and Social Comparison
Eukaryotic Transcription Inhibitors
Eukaryotic transcription inhibitors usually contain two distinct domains, a...
Introduction to Special Senses
Effects of EDTA on End-Point Detection Methods
In the visual method, metal-ion indicators (metallochromic dyes), which have distinct colors in their free and complex forms, are added to the mixture to signal the titration's end point. They form stable complexes with metal ions, but these complexes are weaker than the corresponding metal–EDTA complexes. As a...
Tactile and Chemical Senses
Precipitation Titration: Endpoint Detection Methods
In the Volhard method, a standard excess of AgNO3 is first added to the...

