Encapsulation of fluorescent carbon dots into mesoporous SiO2 colloidal spheres by surface functionalization-assisted cooperative assembly for high-contrast latent fingerprint development

Exploiting solid powder fluorescence holds significant potential in diverse domains including medicine and forensics. Conventional fingerprint detection methods often fall short due to low contrast, sensitivity, and high toxicity. To addressing these challenges, we present a novel method for latent fingerprint detection using fluorescent carbon dots (CDs) encapsulated into conventional or mesoporous SiO 2 colloidal spheres (CD@SiO 2 or CDs@ m -SiO 2 ) through a surface functionalization-assisted cooperative assembly process. The synthesized monodisperse CDs@SiO 2 and CDs@ m -SiO 2 spheres, with tuning particle size, adjustable porosity and pore size, and highly dispersed CDs, exhibit improved fingerprint visibility and contrast on various substrates such as glass, stainless steel, and plastic. CDs located in SiO 2 with excellent affinity effectively avoids their solid-state self-quenching phenomenon, which, coupling with mesoporous SiO 2 shell, maximumly retains their fluorescence properties. Our method demonstrates a high contrast, selectivity, and sensitivity in fingerprint detection, offering an environmentally friendly and healthy alternative to conventional techniques, and showcasing a facile route to novel solid-state CDs-based fluorescent materials for forensic analysis.