(127e) Integrated Ion-Exchange Membrane Based Microfluidic Platform for Early Detection of Oral Cancer

Oral cancer belongs to a group of head and neck cancers that has shown a steep increase in its incidence in the last few years. According to The Oral Center Foundation, approximately 43,250 people in the US will be newly diagnosed with oral cancer, a cancer that already claims 7000 deaths annually. In addition to the excessive use of alcohol and tobacco, another major causative agent of the cancer is human papillomavirus serotype 16 (HPV16). HPV16 is found in approximately 40-80% patients. If diagnosed early, the chances of survival are very high (around 80-90%). However, this number decreases dramatically (5-year survival rate is less than 45%) if the tumor is revealed at a late stage, which is usually the case. Thus there is a pressing need for an early screening tool for detection of HPV-based oral cancer.

Recent studies have revealed that a panel of miRNAs contained in patient’s saliva may be good oral cancer biomarkers. These miRNAs in saliva can either be free (mostly confined in exosomes) or come from cancer cells that have been shed off the oral tumor site. Saliva can be easily obtained from an individual during a preventive care visits in a dentist’s office (liquid biopsy) without incurring any pain to the patient and it presents a good biological material for screening.

Our goal is to develop a screening platform for oral cancer that can process and analyze patient’s saliva collected by oral rinses. The platform is designed as a microfluidic chip allowing automated sample processing and analysis based on the detection of miRNAs associated with oral cancer collected from saliva. The integrated platform can be divided into three independent units: (i) pretreatment unit for separation of miRNA molecules from the saliva samples, (ii) a unit to concentrate the loaded miRNA molecules and, (iii) ion exchange membrane sensor pre-functionalized with probes specific to oral cancer miRNA molecules. The miRNA detection is based on a so-called surface charge inversion phenomenon which occurs as a result of hybridization of negatively charged miRNA molecules to corresponding probes covalently attached on the positively charged ion exchange membrane. The hybridization is easily detected by measuring current-voltage characteristic of the membrane. The platform is capable of distinguishing two base-pair mismatches in a 22-base pairing segment of microRNAs associated with oral cancer. The limit of detection is 1 fM for short 27 base target molecules in a 15-minute assay. In addition to detection, we have successfully shown on-chip, efficient extraction and concentration of nucleic acid from a target sample into an automated single-chip diagnostic platform. The versatility and simplicity of this biosensor should enable point-of-care diagnostics of other cancer biomarkers and more broadly for other medical diagnostics applications.