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

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.