Hydrophobic-Binding-Driven and Fluoresence-Free Development of Aged Fingerprints Based on Zinc Oxide Nanoparticles

Graphical A hydrophobic binding-driven and fluorescence-free development of aged latent fingerprints using silane modified zinc oxide nanoparticles both in positive and reversed imaging mode is proposed, exhibiting the high contrast, high sensitivity, high selectivity and wide applicability. The requirement of nonfluorescent developers for aged latent fingerprint development is still of great urgency in forensic science. To enhance the specific interaction between fingerprint residue and nano-developers, a γ-methacryloxy propyl trimethoxyl silane (MPTS) modified zinc oxide nanoparticle (ZnO NP) was synthesized. The crystal structure, morphology, surface functional group, thermostability, UV/Vis spectra, photoluminescence and stability of sedimentation were characterized to prove the hydrophobicity, UV blocking nature and nonfluorescence of as-prepared MPTS-modified ZnO NPs. Additionally, after the specific surface area (SSA) of samples with different MPTS amount was analyzed by BET, a competitive adsorption mechanism between silane-ZnO bonding and silane oligomer-ZnO deposition was suggested. In the demonstration of latent fingerprint development, the powder dusting method was utilized on various surfaces both in positive and reversed imaging modes, exhibiting the high contrast, high sensitivity, high selectivity and wide applicability, even for aged fingerprints. Therefore, it provides a new strategy for fast, efficient and inexpensive development of older latent fingerprints in forensic analysis.