Category: Advances in Bioanalytics and Biomarkers

1245-A - A new direction in cellular transport: Osmolyte mediated non-functionalized route for selective cellular probing via label-free plasmonic enhancement

Monday, February 5, 2018
2:00 PM - 3:00 PM

Engineered nanoprobes have been at the forefront amongst the current technological innovations in biomedical sciences. These nanoprobes seek to revolutionize the way we study the complex changes in cells and tissues, which form the basis of several diseases in an individual. While such nanoparticle-based diagnostic platforms are rapidly gaining a foothold in diagnostic and prognostic applications, one of the outstanding challenges is to selectively transport these nanoparticles into a cell in a controlled fashion. The associated toxicity of the functionalized nanomaterials stemming from long-term exposure impedes normal cellular function, damages the cell, and renders it unsuitable for imaging applications. Functionalization routes such as PEGylation have yielded desired attributes such as recognition, uptake, and reduced toxicity but suffer from poor sensitivity for plasmon-enhanced spectroscopic sensing methods such as surface-enhanced Raman spectroscopy (SERS). In such surface enhancement techniques, the direct contact between the analyte and the surface is key to the enhancement process, and thus a trade-off has to be found between enhancement efficiency and toxicity. In order to solve this conundrum, we have discovered a new approach for nanoparticle transport into live cells using fully non-functionalized route. We report a trehalose-mediated route for nanoparticle internalization while maintaining cell viability. Trehalose is known to be an exceptional protein stabilizer and has been shown to inhibit nanoparticle-induced aggregation of protein molecules. While the silver nanoparticles are known to disrupt and denature the cell surface receptor proteins and diffuse freely into the cytosol and compromising the viability of the cell, the trehalose-mediated approach ensures selective uptake through endocytosis. The nanoparticle-prostate cancer cell interaction was quantitatively studied through transmission electron microscopy technique. The results indicate the existence of a dynamic equilibrium between “free” cytosolic diffusion of the nanoparticle and endocytosis through vesicle formation. Trehalose shifts the scale in the favor of vesicle formation and hence masks the toxic effects of the nanoparticles. The molecular interaction was probed through SERS in a label-free manner, which helped in directly deciphering the conformation state of the interacting proteins in real time. Spectral interpretation pointed to the retention of protein conformation and enhancement of protein stabilization in the presence of trehalose solution. The aggregation of nanoparticles was greatly reduced on the surface of the cells in presence of trehalose further indicating the stabilization activity of trehalose during the interaction of nanoparticles with the plasma membrane. Specifically, improvement of cell viability and selective endocytic uptake in a trehalose microenvironment facilitates the use of SERS in longitudinal studies, such as in measurements of cell-drug interactions.

Soumik Siddhanta

Postdoctoral fellow
Johns Hopkins University
Baltimore, MD

Soumik Siddhanta is a postdoctoral fellow in the Department of Mechanical Engineering working with Prof. Ishan Barman. His current research focuses on the development of nanoprobes for spectroscopy and imaging applications. During his Ph.D. studies, he had worked on developing label-free methods to probe small molecule-protein interactions through surface-enhanced Raman spectroscopy. His areas of interests include molecular imaging, vibrational spectroscopy, plasmonics, and biophotonics. He holds a BSc in Chemistry and MS and Ph.D. in Materials Science. He is the recipient of the American Society for Laser Medicine & Surgery Research Grant, 2016-'17 and is also a Hopkins Engineering Applications & Research Tutorials (HEART) program instructor and a Teaching As Research (TAR) Fellow at JHU.