Shrimp-Shell-Derived Carbon Dots for Quantitative Detection by Fluorometry and Colorimetry: A New Analytic Chemistry Experiment for University Education

Combining the achievements of scientific research projects with experimental teaching, a new comprehensive experiment of "shrimp-shell-derived carbon dots for quantitative detection by fluorometry and colorimetry" was designed for undergraduate college students. The blue-emissive carbon dots (SS-CDs) are synthesized with waste shrimp shell as raw material through a one-step hydrothermal method. Dialysis and freeze-drying are then used for the purification of carbon dots. The structure of the carbon dots is characterized with the assistance of technicians from the testing center. After obtaining the characterization data, students analyze and plot it through Origin. Based on the selective interaction between carbon dots and cobalt ions, it can be used as a fluorescence sensor for Co2+, with an average detection limit of 1.68 μM. The doping of iron ions in SS-CDs endows them with excellent peroxidase activity. In the presence of 3,3′,5,5′-tetramethylbenzidine (TMB), H2O2 and glucose can be detected by a colorimetric method, with an average detection limit of 6.02 μM for glucose. This experiment has received positive feedback from the students in our school. First, the synthesis of carbon dots uses waste biomass as raw material, which has the advantages of a wide range of sources and environmental friendliness. Second, the hydrothermal method is easy to operate under mild conditions, which is very suitable for undergraduate students. Third, the fluorometry and colorimetry for ions and glucose detection have the advantages of simple operation, low equipment requirements, and high detection sensitivity. Through this experimental training, students will have a better understanding of the conventional preparation and purification methods of nanomaterials, the use of absorption and fluorescence spectra, and the detection principles of fluorometry and colorimetry.