Laser Systems in Medicine

Laser Systems in Medicine:  

Monitoring Health From the Gene Level to Single Cell, Tissue and Whole Body Systems

This presentation provides an overview of recent developments in our laboratory for several laser-based technologies that allow biomedical diagnostics from the gene level to single-cell, tissue and whole body systems. The first technology involves interactions of laser radiation with metallic nanoparticles, inducing very strong enhancement of the electromagnetic field on the surface of the nanoparticles. These processes, often called ‘plasmonic enhancements’, produce the surface-enhanced Raman scattering (SERS) effect that could enhance the Raman signal of molecules on these nanoparticles more than a million fold. The SERS technology can be used to directly detect chemical species and biological species with exquisite sensitivity. A SERS-based nanoprobe technology, referred to as ‘Molecular Sentinel’ nanoprobes, has been developed to detect DNA targets of pathogenic agents (e.g., HIV) and biomarkers of diseases (e.g., BRCA1, ERB2 breast cancer genes). Using nanofabrication, SERS-based plasmonic nanochip systems can also be developed for use as diagnostic systems for point-of-care and global health applications.

In the field of biosensing of individual cells a unique advance has been the development of optical nanosensors, which have dimensions on the nanometer (nm) size scale.  Using lasers as excitation sources for these nanosensors, it has become possible to probe physiological parameters (pH), individual biochemical species (DNA adducts) and monitor molecular pathways (apoptosis) in a single living cell. These nanosensors lead to a new generation of nanophotonic tools that can detect the earliest signs of disease at the single-cell level and have the potential to drastically change our fundamental understanding of the life process itself.

For in vivo medical diagnostics of tissue and whole body systems, an optical diagnostic technology based on laser‑induced fluorescence (LIF) has been developed for direct in‑vivo cancer diagnosis without requiring biopsy. For detection of gastro-intestinal (GI) cancer, endogenous fluorescence of normal and malignant tissues was measured directly using a fiberoptic probe inserted through an endoscope.  The measurements were performed in vivo during routine endoscopy. The potential of the LIF technology for detection of other types of cancer (skin, brain tumors) will be discussed. Theses optical biopsy technologies could revolutionize medical diagnostics since the measurements are performed almost instantaneously (in seconds) and no biopsy tissues are required.

Laser technologies are definitely bringing a bright future to biomedical research and could ultimately lead to the development of new modalities of early diagnostics, drug discovery, and medical treatment beyond the cellular level to that of individual organelles and even DNA, the building block of life.