Zinc oxide quantum dots embedded in hydrophobic silica particles for latent fingermarks visualization based on time-gated luminescence measurements

In this work we demonstrate a composite material based on silica particles. The particles have been doped with zinc oxide quantum dots which possess long living luminescence. The surface of the particles has been functionalized with phenyl groups using sol-gel process. The new material has been successfully applied for visualization of natural latent fingermarks on several surfaces, in particular, those showing their own luminescence and intensive background staining while using powder dusting, what is of the vital interest of forensic science. The time-gated imaging allows to overcome the background luminescence problem and surface functionalization increases the affinity of the particles to the fingermarks, what improves the selectivity of a new developing agent. The main novelty of the presented approach is the use of composite material that combines two main features-long lifetime luminescence and the ability to preferentially attach to the fingermark, due to hydrophobic interactions. Moreover,the utilization of deposition from the suspension instead of simple powder dusting allows for development of latent fingermarks on the surfaces that are difficult to work with powders (e.g. sticky side of the adhesive tape).