Investigators: Peter So, Moungi Bawendi, and Gabriela Schlau-Cohen

Fluorescence spectroscopy and imaging are key techniques in the repertoire of the biomedical research community. In the Laser Biomedical Research Center, the investigators leverage their expertise in precision spectroscopy, contrast agent development, and coherent spatial and temporal control of ultrafast pulses to develop cutting-edge technologies for analyte-specific investigation of biological systems, from proteins to whole organisms. This fluorescence-based technology research and development builds upon 3D light sculpting techniques and short-wave infrared (SWIR) technologies developed in the current cycle with three exciting new directions:

1. High-throughput deep SWIR imaging

High-throughput depth-resolved fluorescence imaging inside thick tissues has numerous applications in biomedicine, ranging from fields as diverse as hepatology, neuroscience and oncology. Unfortunately, fast imaging speeds and deep imaging depths are often mutually incompatible, mainly due to autofluorescence of the surrounding tissue, absorption, and scattering of the excitation and emission by impeding biological tissue. Working with the Jain laboratory, we aim to utilize short-wavelength infrared (SWIR) emitting quantum dots (QDs) for whole-body animal imaging based on single-photon epifluorescence microscopy, down to a depth of several hundred microns. We also seek to improve the background rejection and axial resolution of this approach. More precisely, we aim to develop two- or three-photon SWIR temporal focusing (TF) excitation method, utilizing high multiphoton cross section QDs (TRD4) and compressive sensing, to image dynamic events several hundreds of microns inside a solid tumor. This aim has direct impact on our collaboration on cancer biology (CP1) Jain Lab. read more>>

2. High-throughput structured light super-resolution imaging

The achievement of super-resolution microscopy was widely celebrated with Nobel prizes in chemistry several years ago. While super-resolution imaging is becoming routine in many laboratories, there are still many challenges and limitations that must be overcome for these imaging approaches to be broadly adopted for biomedical imaging. Some of the key limitations are limited speed, field-of-view, and penetration depth. Equally importantly, most successes in super-resolution are based on fluorescence probes, the extension of super-resolution approach to other optical contrast mechanism is also important (see also TRD2.3). LBRC is developing several new approaches for mapping 3D volume at super-resolution limit based on structured light illumination. The advantage of our approach is that super-resolution information from 3D volume can be acquired in parallel with no additional illumination power as compared with just imaging a 2D plane. With the successful development of these techniques, we hope to use this technique to map the connection diagram over a large brain volume ex vivo and to monitor synaptic junction formation and dissociation in vivo. read more>>

3. Nanometer distance assay

Small and rapid molecular motions often drive dramatic changes in protein systems. Single-molecule Förster Resonance Energy Transfer (smFRET) is a powerful technique to probe conformational dynamics at the nanometer scale. In this aim, we plan to improve the spatial and temporal resolution of smFRET to probe the motions of proteins, revealing the interplay between nanoscale motion and the macroscopic function. We also access these length scales in a near physiological environment while accurately monitoring the dynamics of the structural changes. These two improvements enable a new, mechanistic understanding of ligand binding to receptors and other nanoscale molecular motions. read more>>