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Updated: Jun 24, 2025
A Method for Selecting Structure-switching Aptamers Applied to a Colorimetric Gold Nanoparticle Assay
Published on: February 28, 2015
Label-free direct detection of melamine using functionalized gold nanoparticles-based dual-fluorescence colorimetric
Jincheng Xiong1, Boyan Sun2, Sihan Wang2
1National Key Laboratory of Veterinary Public Health Security, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China; Beijing Key Laboratory of Detection Technology for Animal-Derived Food Safety, China Agricultural University, Beijing, 100193, China; Guangdong Provincial Key Laboratory of Advanced Biomaterials, Shenzhen Key Laboratory of Smart Healthcare Engineering, Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, 518055, China.
Abstract:
Developing a simple, economical, sensitive, and selective method for label-free direct detection analytes is attractive, especially the strategies that could achieve signal amplification without complicated operations. Herein, a dual-fluorescence colorimetric nanoswitch sensing platform for label-free direct melamine (MEL) detection was established. We first explored the relationship between MEL-induced aggregation of gold nanoparticles (AuNPs) and size and determined the optimal size to be 37 nm. Using surfactant Triton X-100 to modify AuNPs and clarify possible interaction mechanisms to improve detection performance. The dynamic changes of surface plasmon resonance absorption peaks in the dispersed and aggregated states of AuNPs were skillfully utilized to match the emission of multicolor gold nanoclusters to trigger the multi-inner filter effect. Accompanied by the addition of MEL-induced AuNPs to change from dispersed to aggregated state, the fluorescence of green-emitting and red-emitting gradually turned on and turned off, respectively. The fluorescence turn-on mode detection limit was 10 times higher than the colorimetric method and as low as 5.5 ng/mL; the detection took only 10 min. The sensor detected MEL in spiked milk samples with a good recovery in the range of 81.2-111.0 % with a coefficient of variation less than 11.4 % and achieved a good correlation with commercial kits. The proposed sensor integrates numerous merits of label-free, multi-signal readout, self-calibration, simple operations, and economical, which provides a promising tool for convenient on-site detection of MEL.
