Microarray Chip
Application to Liquid Biopsy
Since the completion of the human genome program in 2003 it is increasingly becoming apparent that every disease has a genetic component. More than hereditary, acquired genomic changes from environment and lifestyle referred to as epigenetics is 90% of the cause. Liquid biopsy, a noninvasive test to measure DNA and RNA fragments circulating in blood, urine, milk and other biofluids is considered a promising test for diagnosis of diseases at very early stages before any clinical signs appear and personalize medicine for effective therapy. A promising class of biomarkers circulating in virtually all biofluids is microRNA. SEED allows detection and quantification of 10's to 100's of these fragments on a single chip that is needed for specific diagnosis and therapy management. Multiplexing allows the analysis on less than 1 milliliter of blood to obtain results in a day.
A typical microarray chip showing an array of 200-micron spots to detect different sequences of DNA and/or RNA fragments.
Quantifying a miRNA on a single chip by SEED. Three typical miRNAs found in blood to detect cancer are shown. MiRNA from 10 attomolars to 1 nanomolar can be measured in just 100 microliter of biospecimen. Thus, limit of quantification is about 600 copies. No labels or enzymes are needed that typically increase reagent costs by 10 to 100-fold. The inexpensive, low sample volume for analysis is essential for screening and therapy monitoring.
Reading multiple microRNA sequence in blood on a single electrode using SEED. The presence of a particular sequence is obtained by the change in the reduction (red) and oxidation (blue) peaks from solid to dashed line. MiRNAs are small RNA with specific sequences to diagnose variety diseases, such as cancers, cardiovascular, and mental. There are over 2,000 different sequences of miRNA in human body. Typically, a subset of less than 50 sequences are needed to detect particular disease.