Next-generation optical nanoprobes: From quantum biosensing to cellular monitoring

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PROJECT SUMMARY Our research program is directed towards innovating and advancing optical tools for the visualization and quantification of latent biomolecular processes across multiple levels of biological organization. The MIRA project will support and improve our analytical toolkit, which spans from surface-enhanced Raman spectroscopic (SERS)-based molecular imaging probes to self-actuating single-cell analysis platforms and biomimetic structures for cellular mechanotyping. Crucially, with support from the MIRA proposal, we will develop three new, complementary platforms to address pressing questions in multiplexed molecular analysis, intracellular magnetic sensing, and targeted imaging of cells and tissues. First, we plan to realize a novel Raman spectroscopic sensing method by fusing SERS with coherent vibro- polariton interactions in the strong coupling regime. While highly desirable, achieving vibrational strong coupling (VSC) between ground-state molecular vibrations and an optical cavity has remained elusive. Combining SERS nanoprobes with rationally designed Fabry-Perot cavities, we present a practical scheme to render VSC that would simultaneously enhance the strength of Raman scattering and enrich its spectral features paving the way for ultrasensitive and highly multiplexed analyte detection. Second, we aim to develop an ultrasensitive nanoscale magnetometer to probe spin effects in biomolecules, an important but poorly understood quantum effect in biological systems. We will implement a DNA-assisted self-assembly approach to pair nitrogen vacancy-center in nanodiamond (NVnD) with plasmonic nanocavities. The accompanying enhancements in NVnD sensitivity and spatiotemporal resolution will permit the detection of currently undetectable ion flux-induced weak magnetic fields (WMF) and to examine the role of WMF in affecting the spin dynamics of cryptochrome-generated radical pairs. Third, we seek to harness biocompatible click condensation reactions to create a new class of synthetic peptide-based Raman imaging nanoprobes involving enzyme-regulated intracellular self-assembly. Our nanoprobes offer multiple advantages for targeted cellular imaging: higher accumulation and reduced efflux due to in situ probe assembly; high sensitivity due to the presence of repetitive units of a π-conjugated functional group in a single structure; and exquisite specificity owing to the easily distinguishable vibrational mode in the cell silent spectral region.