Diagnostic optical sequencing
Advances in precision medicine require high-throughput, inexpensive, point-of-care diagnostic methods with multi-omics capability for detecting a wide range of biomolecules and their molecular variants. Optical techniques have offered many promising advances towards such diagnostics. However, the inability to squeeze light with several hundred-nanometer wavelengths into angstrom-scale volume for single nucleotide measurements has hindered further progress. Recently, a block optical sequencing (BOS) method has been shown for determining relative nucleobase content in DNA k-mer blocks with Raman spectroscopy, and a block optical content scoring (BOCS) algorithm was developed for robust content-based genetic biomarker database searching. Here, we performed BOS measurements on positively-charged silver nanoparticles to achieve 93.3% accuracy for predicting nucleobase content in DNA k-mer blocks (where k=10), as well as measurements on RNA and chemically-modified nucleobases for extensions to transcriptomic and epigenetic studies. Our high-accuracy BOS measurements were then used with BOCS to correctly identify a {beta}-lactamase gene from the MEGARes antibiotic resistance database and confirm the Pseudomonas aeruginosa pathogen of origin from <12 content measurements (<15% coverage) of the gene. These results prove the integration of BOS/BOCS as a diagnostic optical sequencing platform. With the versatile range of available plasmonic substrates offering simple data acquisition, varying resolution (single-molecule to ensemble), and multiplexing, this optical sequencing platform has potential as the rapid, cost-effective method needed for broad-spectrum biomarker detection.