Abstract
It is estimated that the number of new cases of oral cancers worldwide is 529,000 and more than 300,000 deaths each year. The five-year survival rate remains about 50%, and the low survival rate is believed to be due to delayed detection. The primary detection method is through a comprehensive clinical examination by a dentist followed by a biopsy of suspicious lesions. Systematic review and meta-analysis have revealed that clinical examination alone may not be sufficient to cause the clinician to perform a biopsy or refer for biopsy for early detection of OSCC. Therefore, a non-invasive, point-of-Care (POC) detection with high sensitivity and specificity for early detection would be urgently needed, and using salivary biomarkers would be an ideal technology for it. S100 calcium binding protein P (S100P) mRNA presenting in saliva is a potential biomarker for detection of oral cancer. Further, surface enhanced Raman spectroscopy (SERS) has been shown to be a promising POC diagnostic technique. In this research, a SERS-based assay using oligonucleotide strains was developed for the sensitive and rapid detection of S100P. Gold nanoparticles (AuNPs) as a SERS substrate were used for the conjugation with one of two unique 24 base pair oligonucleotides, referred to as left and right DNA probes. A Raman reporter molecule, malachite green isothiocyanate (MGITC), was bound to left-probe-conjugated AuNPs. UV-vis spectroscopy was employed to monitor the conjugation of DNA probes to AuNPs. The hybridization of S100P target to DNA-conjugated AuNPs in sandwich-assay format was confirmed by Raman spectroscopy and shown to yield and R2 of 0.917 across the range of 0-200 nM and a limit of detection of 3 nM.
