Synthesis Of Magnetic Composite Nanomaterials And Their Application In Latent Fingerprint Development

The development of latent fingerprint identification technology have great significance for the scene investigation,judicial expertise and forensic science and other fields.The ultimate purpose is to analyze and summarize the various characteristics existing in the fingerprint and then identify the individual who left the fingerprint.It can not only provide clues for the investigation and solve the case,but also can provide the basis for the trial.The methods for traditional visualization of latent fingerprints include powder method,small particle suspension method,"502"glue method,iodine fuming method etc.These methods have certain effects for visualization of latent fingerprints on ordinary surfaces.But the disadvantages are also obvious,such as toxic,DNA damage and endanger the health of technicians,complicated operation and easy to object background interference,cause serious pollution to physical evidence,the powder easy to accumulate and uneven thickness.With the emergence of a variety of new nanomaterials for the visualization of latent fingerprint,it has become the focus of the attention of fingerprint researchers.The small size,large specific surface area and higher surface activity of the nanomaterials make them effective for the visualization of latent fingerprints on various complex object surfaces.In this paper,two different magnetic nanocomposites（Fe₂O₃/MCMs,Cur-Fe₂O₃/MCMs）were prepared using hollow mesoporous carbon spheres（MCMs）as carriers,which were applied to different object surfaces for latent fingerprint development as follows.（1）Preparation of hollow mesoporous carbon spheres loaded Fe₂O₃and its application in latent fingerprints detectionThe hollow mesoporous carbon spheres with high specific surface area were prepared by the sol-gel method,and then loaded with iron trioxide.The average particle size of the prepared magnetic hollow mesoporous carbon spheres was about 101.21 nm.The nanomaterials were found to be well dispersed and uniform in size by electron microscopy at70,000-150000 magnifications.Magnetic hollow mesoporous carbon spheres could successfully develop latent fingerprints on the surface of permeable and impermeable objects.The developed fingerprints are clear,and the detailed features are obvious.Compared with traditional materials for latent fingerprints detection,it has the advantages of simpler operation,low toxicity and less pollution.（2）Preparation of dye-loaded magnetic hollow mesoporous magnetic spheres and its application in latent fingerprints detectionThe fluorescent magnetic hollow mesoporous carbon spheres were prepared by impregnation method using monodisperse magnetic mesoporous carbon spheres as the carrier and modified with curcumin.The as-prepared fluorescent magnetic materials were uniform in size with an average particle size of about 115.97 nm.The fluorescent materials could effectively enhance latent fngerprints deposited on various object surfaces,including permeable objects and non-permeable objects.The legible and clean-cut fngerprint images were observed on the various surfaces with high contrast,high sensitivity and good selectivity.The fluorescent magnetic materials have great potential applications in the field of criminal investigation.