Red emissive carbon dots (R-CDs) and their analytical sensing applications

Since their serendipitous discovery in 2004, carbon dots (CDs) have attracted widespread attention for analytical sensing applications. Nevertheless, blue-green emissive CDs suffer from drawbacks such as photodamage and interference from auto-fluorescence, which limit their practical utility. To address these challenges, red-emissive carbon dots (R-CDs) have been introduced, offering reduced photodamage and lower background fluorescence. In recent years, R-CDs have gained considerable attention due to their favorable optical characteristics, low toxicity, and excellent biocompatibility. This review, for the first time, focuses on R-CDs as fluorescent sensors for analytical applications. The synthesis strategies and the factors affecting R-CDs are discussed. In addition, their applications in the detection of biomolecules, contaminates, drugs, dyes, ions, pesticides, pH, temperature, and, metal ions are presented. Finally, recent progress in the development of novel R-CDs is highlighted, with particular emphasis on their sensing applications. • The reason for conducting this review is their ability to provide reduced photodamage and lower background fluorescence. • The potential applications of R-CDs as analytical sensors for a wide range of analytes are summarized. • This work represents the first review focusing on these R-CDs and their analytical sensing applications.