(51e) In Vivo Multiplexed Nanodiagnostics for Assessing Biological Heterogeneity

Heterogeneity is a fundamental property of a biological system. The genetically homogeneous bacteria exhibit inherent phenotype heterogeneity, in which their subpopulation can always survive from viruses or antibiotic treatments. Cancer is a heterogeneous disease, in which the constituent tumor cells diversify to various molecular phenotypes. Comprehensive assessment to such heterogeneity and functional diversity of the biological components is essential for the informative disease diagnosis and the patient-specific therapeutic decision, which necessitates the use of high-dimensional and multiplexing tools. Since the expression of the biological heterogeneity is most prominent in living subjects, I aim to develop an intravital multiplexed imaging platform to simultaneously monitor as many biological components as possible.

Here I present a noninvasive and highly multiplexed in vivo preclinical imaging platform based on multi-color spectral palettes of surface-enhanced Raman scattering (SERS) nanoparticles¹. I create nine spectrally distinct gold core-silica shell structured near-infrared resonant SERS (NIR-SERRS) nanoparticles, which offer both (i) high imaging sensitivity as the traditional NIR fluorescence imaging and (ii) high multiplicity originated from the narrow spectral bandwidth of SERS spectra. From the 9 NIR-SERRS nanoparticles, I select five color-encoded nanoparticles and demonstrate a noninvasive and five-plex in vivo imaging of the 5-color nanoparticles targeting to subcutaneous tumors in nude mice. The in vivo multiplexed imaging allows dynamic monitoring of the 5-color NIR-SERRS nanoparticles retention in the tumor, which demonstrates the great potential for noninvasive assessment of multiple biological targets within the tumor microenvironment.

Next, I develop biodegradable plasmonic gold supraparticles for clinical translation of the nanoparticle-based in vivo multiplexed imaging platform. The supraparticles are created through the assembly of gold atomic clusters. While the long-term exposure of gold nanoparticles to the liver has limited their use in humans, the gold supraparticles are biodegradable to renally excretable atomic clusters through in vivo enzymatic reaction. The supraparticles exhibit photoacoustic and Raman responses under the NIR excitation, which enable the noninvasive in vivo imaging applications.

The presented work will provide an excellent platform for the noninvasive analysis of heterogeneous biological systems such as tumors, in which multiple biomarkers should be simultaneously monitored in living subjects. It will also enable tracking multiple immune cells along with tumor biomarkers, and classifying molecular subtypes of tumors in the context of tumor-immune environments. Finally, I envision that the biodegradable design of the plasmonic supraparticles proposed here will accelerate the clinical translation of the nanoparticle-based in vivo multiplexed imaging platform^2,3.

1. Yu J.H. et al. Highly Multiplexed Five-Color Noninvasive Tumor Imaging of Near-Infrared Resonant Surface-Enhanced Raman Nanoparticles In Vivo. submitted (2020).
2. Park S.-m., Aalipour A., Vermesh O., Yu J.H. & Gambhir S.S. Towards clinically translatable in vivo nanodiagnostics. Nat. Rev. Mater. (2017).
3. Yu J.H. et al. High-resolution three-photon biomedical imaging using doped ZnS nanocrystals. Nat. Mater. (2013).