Recent advances in the rational synthesis of red-emissive carbon dots for nanomedicine applications: A review

Abstract

Carbon dots (CDs) with incomparable optical properties are promising nanoparticles for biological and medical applications such as imaging, biosensing, and drug delivery. Because their absorption and emission mechanism is not fully understood, the synthesis of CDs with desire optical characteristics is more challenging. Many efforts have been conducted to obtain robust and reproducible methods for blue and green CDs, but there is no controllable procedure for producing permanent red fluorescence emitting CDs. This review discusses various studies evaluating the effective parameters for synthesizing red carbon dots (R-CDs) to obtain a rational and predictable synthesis method for this type of CDs. Following an introduction, the first section covers the main tunable features of R-CDs. A section on R-CDs preparation follows this by selecting suitable synthesis methods, selecting suitable precursors, computational modeling, statistical optimization, and purifying methods. Several tables are presented that give an overview of each section. The final sections deal with the relationship between the structure of R-CDs and their optical properties, as well as the main nanomedicine applications of R-CDs. The conclusion summarizes the current status, addresses challenges, and gives an outlook on potential future trends.