Highly Sensitive Portable Test Strip Based on Carboxylate Cellulose-Derived Carbon Dots for On-Site Visual Detection of Nitrite in Food Samples

As a common food additive, nitrites are used in processed meat products, primarily for color enhancement and preservation. Excessive intake of nitrites can lead to high toxicity to pose a significant risk to human health, including potential carcinogenicity and even death. Consequently, developing a rapid and sensitive method for nitrite detection is crucial for food safety monitoring. Herein, this study is developing a nitrite detection system utilizing blue-fluorescent carbon dots (CDs) derived from carboxylate cellulose. This system operates by detecting the quenching of CDs fluorescence, which is caused by Fe³⁺ ions generated via the oxidation of Fe²⁺ by nitrite under acidic conditions. Within a concentration range of 1–1000 µm, the system demonstrates a strong linear relationship between CDs fluorescence intensity and nitrite concentration, with a detection limit of 0.42 µm. Furthermore, this study is designing a novel CDs-based fluorescent test strip for rapid and visual nitrite quantification in pakchoi cabbage samples, enabling detection within 30 min. Overall, the CDs-based fluorescent test strips hold great promise for enhancing food safety monitoring, ensuring effective nitrite control, and protecting public health from the potential risks associated with excessive nitrite consumption.