A Novel Nanoparticle-Based Method to Isolate DNA From Dried Saliva and Semen Samples

Document Type : Original Articles


Department of Life Sciences, School of Sciences, Gujarat University, Ahmedabad, India.



Objectives: Saliva and semen stains may be found at crime scene (suicide, homicide, kidnapping, rape, sexual assault, poisoning, etc.). Through, which DNA can be isolated and individual can be identified. DNA can be of great importance in forensic science investigation to identify individuals. Currently, there are enormous methods to isolate DNA from biological fluids. The current study employed nanoparticle–biomolecule conjugate method to isolate DNA. Materials & Methods: A nanoparticle-biomolecule conjugate is a magnetic nanoparticle with biomolecules attached to its surface. Saliva and semen were collected using cotton swabs from different surfaces (tile, steel, aluminum, glass, iron, wood, etc.) on which saliva and semen were poured and allowed to dry earlier as to create simulated crime scene. Magnetic nanoparticles (Fe3O4) act as solid phase support to isolate DNA from saliva and semen stains. In the current study, cells and spermatozoa were extracted from saliva and semen swabs, respectively. Cell lysis was performed to extract epithelial cells from saliva and spermatozoa from semen and magnetic nanoparticles and biomolecule conjugate were added to the lysed cells to bind to DNA. Results: Application of external magnetic field helped to settle down nanoparticle-biomolecule conjugate and thus separate DNA from other cell components. Spectrophotometer Nanodrop technology was employed to perform the readings, which confirmed the presence of DNA at 260/280 ratio and quality of DNA was compared with the DNA isolated using the two different methods.Conclusion: The current study aimed at developing all new methods to isolate DNA from dried saliva and semen samples using magnetic nanoparticles by reviewing the methods developed earlier to isolate DNA from blood and tissue using magnetic nanoparticles. With modifications in the method and chemical preparation, a new method was successfully developed. DNA was isolated successfully; and confirmation was made by analyzing DNA through Nanodrop spectrophotometer.


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