Development of fluorescent mesoporous-coated sodium fluorescein modified with 4-dimethylaminobenzoic acid composites for sensitive latent fingerprint detection

The application of fluorescent small molecules is greatly limited because they tend to photobleach and cause potential harm to organisms. However, SiO₂ with fluorescent properties can be obtained by incorporating fluorescent small molecules into the preparation process using Stöber’s method. In this study, we successfully synthesized and prepared nanosized SiO₂ spheres doped with sodium fluorescein (FS). The resulting fluorescent material exhibited excellent optical properties similar to FS and demonstrated good optical stability. Additionally, the surface of SiO₂ spheres was easily modified, allowing for the introduction of foreign groups or small molecules. By incorporating 4-dimethylaminobenzoic acid (DBA), the final FS@SiO₂@DBA fluorescent material enhanced the affinity for latent fingerprints. The use of FS@SiO₂@DBA composites for latent fingerprint development demonstrated significant development effects on various substrates, including slides, metal locks, rough marble, galvanized iron sheets, quartz crucibles and blue plastic housings. These findings suggest that FS@SiO₂@DBA has a significant impact on latent fingerprint development.