Universal ZnCdSe@ZnS QDs nanobead-based intelligent point-of-care testing platform for on-site detection of artificial sweetener in food

Sodium saccharin, a synthetic sweetener commonly used in the food industry, is potentially carcinogenic, and excessive consumption causes harm to the liver and nervous system. Consequently, developing an on-site approach for the precise quantification is of utmost importance and exigency. In this work, a straightforward, expeditious, and highly sensitive intelligent point-of-care testing (iPOCT) method found on quantum dot nanobeads (QBs) was devised for detecting sodium saccharin in food. QBs served as fluorescent labels previously being coupled to anti‑sodium saccharin antibodies. The quantification of sodium saccharin depended on a portable smartphone reader device. The iPOCT showed expeditious detection of sodium saccharin within 15 min. It presented a relatively low limit of detection of 0.18 ng/mL and an extensive linear range from 10 to 5 × 10⁴ ng/mL. In the case of preserved fruit, jelly, and fruit wine, the recovery rates ranged from 97.60% to 105.51%, with relative standard deviations below 8.90%, consistent with the results obtained from high-performance liquid chromatography (HPLC). Unlike conventional detection methods that require complex instrumentation, specialized operation, and off-site analysis, our QB-based iPOCT offers enhanced sensitivity, simplified operation, low cost, and rapid on-site readout. Consequently, this method serves as an effective on-site monitoring tool for sodium saccharin, providing essential technical support for quality supervision within the food industry.