Proteome-wide biomarker quantification and target screening.

Abstract

e15205 Background: Existing drug development programs are represented by only a few hundred protein targets. A large subset of the ~20,000 proteins encoded by the human genome remain undiscovered. Proteome-wide “druggability” screening may lead to new targets for therapeutics. Methods: The NanoMosaic platform is a digital immunoassay technology that achieves sub-pg/ml level sensitivity, whole-proteome level multiplexing capability, and 7 logs of dynamic range. The platform overcomes the sensitivity and dynamic range limitations of traditional protein arrays and mass spectrometry. Results: The NanoMosaic technology is powered by silicon nanoneedle biosensors that are densely integrated on a plate and manufactured with CMOS-compatible nanofabrication processes. Each nanoneedle is a label-free biosensor, functionalized with capture antibodies. Its scattering spectrum changes when an antigen binds to its surface. Each analyte specific sensing area consists a total of ~23k nanoneedles divided into a digital region (~20k nanoneedles) and an analog region (~3k nanoneedles). The digital nanoneedles provide the single molecule sensitivity. Therefore, at ultra-low concentration when antigens that are captured by the nanoneedles follow Poisson statistics, the number of antigens can be quantitated by counting the presence or absence of color changes of individual nanoneedles in a binary fashion. As the protein concentrations increase, the binding event counts increase accordingly and achieve saturation when all nanoneedles capture more than one protein. Above the digital saturation concentration, an adjacent section of analog nanoneedles perform quantitative analysis based on the level of color change, thus providing a wider dynamic range up to 1ug/ml. Ultrahigh level multiplex can be achieved by parallelizing the detection in a microarray format without loss of the sensitivity and dynamic range. A 20,000-plex proteome-wide study can be achieved with a total of 5 billion nanoneedles on a ~70mm by 70mm chip. Conclusions: In conclusion, proteome-wide biomarker quantification and target discovery can be performed on the NanoMosaic platform at higher sensitivity, wider dynamic range, lower cost and higher throughput than is currently possible by mass spectrometry or traditional immunoassays.