Raman Spectroscopy: A Promising Technique for Analyzing Nucleic Acid Refractory to PCR Amplification

Ancient DNA (aDNA) refers to the genetic material found in dead paleontological and archeological samples. Being subject to various types of stressors, it undergoes different hydrolytic and oxidative post mortem modifications that result in the formation of DNA lesions. These lesions are found to either block the DNA polymerase during replication or induce nucleotide misincorporations. Besides, aDNA samples occur in minimal quantities; which represents an additional obstacle that researchers have to overcome in order to study aDNA. The earliest major efforts included the use of molecular cloning and polymerase chain reaction (PCR) to amplify aDNA sequences. These techniques were later found to be associated with a number of false results and unauthentic findings. There have been numerous attempts to eliminate the shortcomings of PCR and improve the quality of aDNA through avoiding contamination, repairing lesions, using translesion polymerases, etc. However, the majority of these have failed to yield accurate and specific results. Surface- enhanced resonance Raman scattering (SERRS), on the other hand, starts in the right foot by introducing a sensitive non- enzymatic approach for the specific detection of single- and double-stranded DNA. The ability of this method to evade DNA degradation is particularly important for not only studying aDNA, but also analyzing DNA refractory to PCR amplification in processed products.