ORIGINAL PAPER Rapid Fluorescence Spectroscopic Characterization of Salivary DNA of Normal Subjects and OSCC Patients Using Ethidium Bromide Manoharan Yuvaraj & Prakasarao Aruna & Dornadula Koteeswaran & Palraj Tamilkumar & Singaravelu Ganesan Received: 23 July 2014 /Accepted: 25 November 2014 # Springer Science+Business Media New York 2015 Abstract Recently, deoxyribonucleic acid (DNA) based bio- marker(s) detection has been employed for cancer diagnosis. Earlier reports have suggested the presence of more DNA in the saliva of oral squamous cell carcinoma (OSCC) than normal by electrophoresis technique. Based on these, steady state and excited state kinetics of salivary DNA has been performed with 27 normal subjects and 67 OSCC patients saliva using ethidium bromide as a probe to look for the possibility in discrimination between them. On statistical analysis the sensitivity and specificity of 88.9 and 94.0 % has been achieved from the fluorescence emission spectra and 88.9 and 92.5 % with that of fluorescence excitation. Keywords Saliva mass screening . Salivary DNA . Ethidium bromide . Fluorescence steady and excited state kinetics . Simple and rapid technique Introduction Cancer is one of the most common dreaded diseases in the world. Among the various cancers, oral squamous cell carcinoma (OSCC) has been ranked number sixth [1, 2]. In the Asian continent, India in particular, the incident rate of oral cancer is predominant and has been ranked number one among males and third among females [3]. Histopathological discrimination of disease has been considered as the golden standard method, however, as the patients are not reporting to the physician at the early stage of the disease, due to lack of symptoms, the mortality rate has been raised up to 45 % for the last 5 years [4]. Early diagnosis of oral cancer may im- prove the life span of the patients due to treatment outcome [5]. Hence, there is a need for a novel rapid method for the early diagnosis of cancer. Any alteration in deoxyribonucleic acid (DNA), ribonucleic acid (RNA), proteins and metabolites at molecular level are attributed to the onset of the disease and hence for the case of cancer also. In the case of cancer excess metabolic end products have been released due to the uncon- trolled proliferation. These metabolites may have their impres- sion in the body bio-fluids viz., blood [6, 7]; urine [8], saliva [7, 9–13]. In this context, diagnosis of disease at molecular level using biomarkers present in bio fluids have shown encouraging results. Among the various bio fluids, saliva was easily accessible and informative and hence, it has been considered for analyzing any changes at proteomics, geno- mics and metabolomics levels [10–13]. Nowadays, diagnosis of disease based on the characterization of DNA and RNA level has been considered as one of the highly sensitive and effective methods [10, 11]. Although, isolation and detection of DNA present in saliva by electrophoretic technique has been the most common and an accurate method, it was tedious and time consuming. In electrophoretic technique, ethidium bromide (EB) has been added as an intercalating cationic fluorescent dye, which covalently binds with the DNA helix and give fluorescence in the region where DNA present, under the illumination of ultraviolet light. In this regard, many have studied the interaction of EB with DNA by steady [14–17] and M. Yuvaraj : P. Aruna : S. Ganesan (*) Department of Medical Physics, Anna University, Chennai 600 025, India e-mail: sganesan@annauniv.edu S. Ganesan e-mail: sganesan_61@yahoo.com D. Koteeswaran Department of Oral Medicine and Radiology, Meenakshi Ammal Dental College and Hospital, Chennai 600 095, India P. Tamilkumar Radiation Oncology, Dr. Rai Memorial Cancer Institute, Chennai 600018, India J Fluoresc DOI 10.1007/s10895-014-1482-0