LIBS-based multi-element coded assay for ovarian cancer application

We report on a new application of laser induced breakdown spectroscopy (LIBS) for the diagnosis of diseases such as ovarian cancer. We perform detection of ovarian cancer biomarker CA 125 based on LIBS measurements. Immunoconjugated Silicon particles are incubated with the affinity agarose beads carrying CA125 molecules. In the competitive affinity method Si particles carrying IgG molecules are pre-incubated with CA125. This pre-incubation decreases the numbers of free IgG molecules available for consequent interaction with the affinity beads. Thus less Si particles are attached to the agarose beads and consequently smaller Si peak area is measured by LIBS. We demonstrate a limit-ofdetection about 30 ppb for model protein avidin. We use two-element coded micro-particles to yield spectroscopic emission code using LIBS. We show that LIBS-based data collecting technique provides methodology for identification of biomarkers and cost-effective device for future clinical applications.