Preparation Of Mesoporous Silicon Fluorescent Nanomaterials And Detection Of Their Potential Fingerprints

Fingerprint is regarded as an important evidence of personal identification because of its uniqueness and lifetime invariance,and is widely used in criminal investigation,security inspection,access control and so on.From the perspective of imaging,it is of great significance to maximize the sensitivity,contrast and selectivity of fingerprint detection for criminal investigation and exploration.The choice of detection method usually depends on the nature of the substrate on which the fingerprint is deposited;Matrix porosity,reactivity,and fluorescence properties must be considered when selecting existing methods or developing new ones.In addition to being able to perform optical imaging,another increasingly important consideration is that some of the chemical information that may be contained in the fingerprint should not be compromised during imaging.Mesoporous silica nanoparticles（MSNs）NPs have been widely used in biochemical detection due to their large specific surface area,strong adsorption,good biosafety and uniform dispersion.Based on the above considerations,in this paper,two novel fluorescent nanomaterials（Cl-PFR@MSN-NH₂ and RB@MSN-UC）were successfully prepared using mesoporous silica as the substrate for the detection of potential fingerprints on various substrates.（1）As a non-metallic fluorescent reagent,chlorinated phenolic resin（Cl-PFR）nanoparticles（NPs）were synthesized by a simple method.The synthesized Cl-PFRNPs can emit strong green fluorescence under 365nm UV light.MSNs coated Cl-PFR composites were prepared by mixing Cl-PFR and MSNNPs together.The prepared Cl-PFR@MSN-NH₂ composite combines the excellent color fluorescence properties of Cl-PFR with the low toxicity and adhesion of MSNs.Under ultraviolet radiation,fingerprints on different substrates（glass,paper,aluminum plate,rough stone,tape）can be clearly observed using the prepared Cl-PFR@MSN-NH₂ composite material.In addition,even after three months of aging and washing many times,the fingerprint marked by Cl-PFR@MSN can still be clearly observed.The composite material provides a simple,economical and non-toxic fluorescent reagent for fingerprint detection applications.（2）Developing fluorescent materials that can selectively identify fingerprints in the presence of strong background interference remains a challenge in latent fingerprint（LFPs）detection.Based on this,using mesoporous silica coated with fluorescent dye rhodamine 6G（RB）after modification of amino functional groups on the surface,by electrostatic adsorption of Mn²⁺doped Na YF₄:Yb,Er upconversion nanomaterials（UC）,successfully prepared fluorescent functional materials that can simultaneously perform optical imaging under ultraviolet and infrared light.Efficient imaging for LFPs.The experimental results show that RGB@MSN-UC has good dispersibility,fast light response,good light reversibility and excellent optical stability.Because it can emit visible light under infrared radiation,the material can realize optical imaging and detection of fingerprints even under strong ultraviolet interference,and realize high contrast imaging of LFPs by excluding background interference,which is of great significance in criminal investigation and detection.