Developing Fingerprints Based On SiO₂ Nanoparticles And The Influence Of DNA STR Typing

Fingerprints not only have strong individual recognition patterns,but also contain DNA which is one of the most important physical evidences in the field of criminal investigation.Therefore,developing fingerprints and sampling DNA on the criminal scenes or physical evidences are urgently needed in the field of criminal investigation.The difficulties of developing fingerprints vary on different material substrates.Thermal paper is a kind of special paper that is often encountered in life.Especially the thermal paper soaked in water often becomes a criminal evidence,so developing fingerprints on it is of great significance.In this paper,mesoporous silica nanoparticles(MSNs)were prepared and loaded with the lipophilic dye Nile Red.The MSNs loaded with Nile red were dispersed in water to prepare suspension.The effect of this suspension on developing latent fingerprints on thermal paper was investigated.The results show that the latent fingerprints on thermal paper can be detected very well.Moreover,latent fingerprints from different volunteers on different material substrates can be clearly detected.In addition,compared with the traditional Nile red and Oil red O methanol aqueous solution methods,the fingerprint appearance detected by the suspension is better and the text information on the thermal paper can be preserved.Latent fingerprints can provide fingerprint patterns and DNA information for further research.It is an important evidence in the field of criminal investigation.However,the existing methods often cannot obtain the two types of information at the same time.This essay developed a technique for transferring fingerprint and sampling DNA at the same time.This method can complete the collection and visualization of fingerprint samples by using tape and SiO₂ suspension.The key of this method is the use of tape to adhere the fingerprint residue and sample DNA in the fingerprints at the same time.Then use the SiO₂ suspension for developing fingerprints on the tape.Finally,the tape is used for extracting DNA and STR typing.It has been proved by experiments that the fingerprint appearance developed by the method is complete,and STR typing can still be studied after visualization,and the method is applicable to multiple donors,different matrix materials and uneven surfaces.The operation material of this method is cheap and easy to obtain,the operation process is simple,and has certain promotion value.