Integrated Nano-Opto-Fluidic System on Sapphire towards Single-Molecule Protein Sequencing - PROJECT SUMMARY/ ABSTRACT Enabled by the development of high-throughput, low-cost nucleic acids sequencing technologies, there have been accelerated development in genomics and transcriptomics in the past two decades, profoundly reshaping our knowledge in biology and medicine. However, similar technologies have yet to emerge for rapid identification and quantification of proteins. This is attributed to more complex structures of proteins, lack of polymerase chain reaction-like amplification methods, cellular heterogeneity, etc. Conventional protein sequencing methods, such as Edman degradation and mass spectrometry, are slow, expensive, and not suitable for detecting low- abundance proteins. Such ensemble measurements also can mask our fundamental understandings on how cells of a particular genotype function and respond to therapeutics. Single-molecule protein sequencing (SMPS) is an emerging research direction that directly reads amino acids sequence from individual protein or peptide molecules. Yet, a promising strategy using fluorosequencing still relies on long Edman degradation cycles and bulky fluorescent microscopes, not ideal for fast and low-cost readout. Electronic SMPS technologies using tunneling or nanopore sensors are emerging methods for development of portable and inexpensive sequencing systems. However, they still face challenges in precise nanofabrication, structural instability, high electronic noise, and inability in detection of all amino acids. To address the multi-faceted challenges in next-generation SMPS, we will design an on-chip integrated, electronic system that incorporates nano-opto-fluidic structures to transduce protein fingerprints into electronic signals at a high speed, a low cost and a small system foot-print. Our platform features an all-sapphire nanopore (AlSaPore) fluidic device that has a small capacitance and a greatly improved structural stability, and accordingly suited for high-speed, low-noise, high-throughput, electronic detection. Further, an ultrathin nitride-based metasurface-integrated circuit (MIC) structure is created on the AlSaPore to optically interrogate the fluorescently tagged single amino acids passing through the nanopore without conventional fluorescent microscopy. Subsequently, the fluorescent tag signals are transmitted through the waveguide and collected by on-chip integrated photodetectors. The optoelectronic channel (IA for amino acids tags) and ionic current channel (IP for protein primary structure) will be synchronously recorded, classified by deep learning algorithms, and used in combination to improve the protein sequencing accuracy. Supported by well-established nitride-on-sapphire device design and manufacturing technology, our MIC-AlSaPore is a scalable and compact platform that achieves single-molecule sensitivity with a potential to read out all 20 amino acids. The development of MIC-AlSaPore platform will have far-reaching impact in biomedicine beyond protein sequencing. It may be used for studying DNA-protein interactions at single-molecule levels, classification of specific genes, genome mapping and de novo assembly. Additionally, it may inspire future multi-omic (genomic, transcriptomic, and proteomic) diagnostic solutions with potential clinical applications.
