One‐Step Synthesis of Solid‐State Photoluminescent Carbon Nanodots from Grains for Latent Fingerprint Detection

Abstract Employing grains (wheat, corn, sorghum and rice) as precursors, a series of carbon nanodots (CDs) have been prepared via one‐step hydrothermal treatment. All the CDs have narrow size distribution, roughly spherical shape and similar optical properties. The size depends on the precursors, which varies from 2 to 25 nm. The CDs without further treatment can overcome aggregation‐induced quenching effect, and emit stable bright blue luminescence under UV light irradiation in both colloidal and solid states. Additionally, the mechanism for the solid‐state fluorescence of CDs was also explored. Moreover, the feasibility of CDs as fluorescent labels for latent fingerprint detection was investigated and the results demonstrate well‐defined papillary ridges with higher sensitivity and wider applicability. The work provides a simple, low‐cost, and promising alternative for latent fingerprint detection in forensic science.