Video

 

First Place: Blood Vessel and Collagen Organization in the Heart.

Kyle P. Quinn, Postdoctoral Scholar, Biomedical Engineering, Tufts School of Engineering
Kelly Sullivan, PhD Student, Biomedical Engineering, Tufts School of Engineering
Zachary S. Ballard , Undergraduate Student, Physics, Brown University
Lauren D. Black, Assistant Professor, Biomedical Engineering, Tufts School of Engineering
Irene Georgakoudi, Associate Professor, Biomedical Engineering, Tufts School of Engineering

Non-linear optical microscopy has an inherent ability to optically section 3D tissues at different depths, because non-linear light-matter interactions typically only occur at the focal plane of the microscope objective. Furthermore, we can detect natural tissue fluorescence and non-centrosymmetric molecule organization without the need for fluorescent dyes or stains, through the use of two photon excited fluorescence (TPEF) and second harmonic generation (SHG) respectively. We are currently using these imaging techniques to examine changes in tissue organization following myocardial infarction in a rat model. Using a titanium:sapphire laser tuned to a 800nm wavelength, we can detect collagen fiber SHG (blue and green) and blood vessel autofluorescence (red). By non-invasively acquiring these high-resolution microstructural images of the tissue and characterizing the mechanical response of the tissue after imaging, we can obtain a detailed understanding of tissue structure-function relationships during myocardial infarction. In this video, individual 1 µm optical sections are displayed as we move deeper within the heart tissue. The 238 x 238 x 100 µm image volume is then reconstructed in 3D and rotated to enable visualization of the 3D organization.

Second Place: Optical Microwell Arrays for Single Molecule Sensing

Huaibin Zhang, Postdoctoral Scholar, Chemistry, Tufts School of Arts and Sciences
Stephanie M. Schubert, Student, Chemistry, Tufts School of Arts and Sciences
Shuai Nie, Student, Chemistry, Tufts School of Arts and Sciences
Kathryn Mayer, Postdoctoral Scholar, Chemistry, Tufts School of Arts and Sciences
David R. Walt, Professor, Chemistry, School of Arts and Sciences

Single molecule detection is an important goalpost in the development of biosensors. Detecting one molecule represents the ultimate limit of sensitivity for such devices, and the ability to detect ultra-low concentrations of disease markers can lead to earlier diagnosis and treatment. In addition, single molecule studies are highly important in molecular biology, as the behavior of many biomolecules (such as enzymes) is heterogeneous and cannot be fully elucidated from ensemble measurements. Therefore, the development of robust techniques for single molecule detection will open up many possibilities for biomedical applications, as well as new areas of fundamental biology research.

This video gives a brief and simple introduction to the single-molecule detection methods developed in the Walt Laboratory at Tufts University. These methods are based on arrays of optically addressable microwells. Microwell arrays are formed by etching the core material of a fiberoptic bundle. This results in 50,000 wells with volumes of 50 femto-liter (5×10-14 L) each on a surface only two millimeters in diameter. Single molecules are isolated by exposing the microwell array to a dilute solution of the target molecule, exploiting Poisson statistics to ensure that the vast majority of wells contain either zero or one molecule. The wells are then sealed, isolating each molecule in its own 50-femtoliter environment. To enable fluorescence-based detection, the target molecule is tagged with an enzyme which acts on a fluorogenic substrate, as in an ELISA. Due to the small volume of the wells, the fluorescent product builds up quickly in the wells where target molecules are present, creating an easily detectible signal. This method allows the researcher to literally count the number of single molecules present, giving unprecedented sensitivity to analyte concentration. This technique has been applied to biomarker detection for prostate and breast cancer, as well as to fundamental studies of enzyme kinetics.

Third Place: Revamping the Kimberley Process

Dani Jenkins, Undergraduate, Tufts School of Arts and Sciences
Stephanie Krantz, Undergraduate, Tufts School of Arts and Sciences
Karen Bustard, Undergraduate, Tufts School of Arts and Sciences
Daniel Goodman, Undergraduate, Tufts School of Arts and Sciences
Meagan Maher, Undergraduate, Tufts School of Arts and Sciences

This video was made for PS 138, Conflict and Natural Resources Fall 2012. Our assignment was to make a video about conflict diamonds addressing conflict prevention workers. The Kimberley Process is an international agreement that prevents the trade of rough diamonds that contribute to conflict. We chose to address members of the Kimberley Process before they meet on November 27-30th to reevaluate the process.