Citrus limetta pulp-waste derived Au@CDs as a colorimetric and spectroscopic probe

Herein, we report a facile colorimetric sensor based upon Au/Carbon Dots (Au@CDs) for selective and sensitive detection of l-cysteine. Au@CDs are synthesized by a green route from CDs via the one-step reduction method. The as-synthesized Au@CDs exhibit characteristic surface plasmon peak at 528 nm. Furthermore, based on the induced aggregation effect, Au@CDs are demonstrated to detect l-cysteine colorimetric detection. The observed colorimetric response is validated with absorption studies. The facile colorimetric sensor offers a detection limit of 1 mM, based on visual color changes. However, with quantitative absorption studies, the theoretical detection and quantification limit was determined to be 28.5 mM and 86.62 mM, respectively, with a standard deviation of 0.002 (n = 3) and sensitivity of 0.001 (absorbance/mM). In addition, the developed probe based on Au@CDs is shown to detect l-Cysteine in biological samples.

Automated summary

In this study, a facile colorimetric sensor based on Au/Carbon Dots (Au@CDs) is developed for selective and sensitive detection of l-cysteine. The sensor offers a detection limit of 1 mM based on visual color changes and has potential applications in biological sample analysis.