Research

Elastic scattering spectroscopy (ESS) for the detection of apoptosis
RA: Bobby Liu   bobbyliu@bu.edu

   Apoptosis is enhanced by most cancer treatment modalities and, in fact, the initial response to successful cancer treatment is often massive apoptosis. Because of this, apoptosis measurements are the primary method for anticancer drug evaluation in vitro. Unfortunately, all current detection methods are invasive and are often inadequately quantitative. Our aim in this project is to develop a fast, inexpensive, and noninvasive method of monitoring the state of apoptosis in a cell culture, allowing for assessment of the apoptotic state of a population of cells without perturbing them in any way. Such a method would also enable monitoring of a single cell sample over time, rather than requiring a new culture at each time point, thereby allowing for a more accurate assessment of cellular response by avoiding culture-to-culture biological variability. With these criteria in mind, we are developing instrumentation to use elastic scattering spectroscopy (ESS) as a detection tool for apoptosis in cell cultures. Changes in the morphology of apoptotic cells should produce measurable differences in the way they scatter light. With the proper analysis algorithms, a quantitative determination of the cellular state can be achieved in real-time. Wavelength-dependent measurements in the near-backward direction have shown that ESS is capable of discriminating between treated and control samples as early as 10 to 15 minutes post-treatment, which is much earlier than most conventional assays can detect its onset. We are currently developing an algorithm that uses Mie theory to relate the collected spectra to the morphological features underlying them to give an assessment of the cells’ progress in the apoptotic process.

Intrinsic field-induced changes in birefringence (FICB) allowing for the optical study of neurophysiology
RA: Ali Badreddine   badredah@bu.edu

   With a deep understanding of single neuron events, neurophysiologists have turned to solving a new problem: How do networks of neurons interact to produce the functions that we observe, like learning?  The tools currently available to them are not well suited for this endeavor, and so neurophysiologists have sought for methods of producing high-resolution spatiotemporal maps of neuronal activity in large areas of brain tissue.  Although tools such as voltage- or calcium-sensitive dies and Intrinsic Optical Signaling (IOS) each have their specific limitations, they have proven that there is a wealth of information to be gained by studying such maps.  IOS in neurons, though usually related to membrane swelling, can be associated with FICB, which are small shifts in the local electric field near a neuronal membrane due to action potential (AP) propagation.
   This project has been oriented toward studying the physiological causes of this phenomenon, and has shown, using a photodiode line array, that it is possible not only to detect APs in the nerve along a line, but to track these APs as they propagate along the nerve, both with stimulus-averaging and ‘live’ in the form of movies. Currently, a brain slice chamber is being designed and built to enable the detection of neuronal network activity in 2D mammalian brain slices. This research could be invaluable in studying the progression of diseases and their effects on AP propagation or membrane function.

Assessment of real-time tissue viability using near infrared light
RA: Joseph Angelo   jangelo4@bu.edu

   Point-of-care feedback techniques are crucial for evaluating biomarkers and, subsequently, providing proper patient care. Furthermore, providing feedback during surgery could allow intervention during a narrow, yet valuable time window, possibly avoiding days of waiting for histology results and reoccurring surgery. Optical methods are gaining popularity in clinical research as a viable technique because they are low cost, non-invasive, portable, and can retrieve endogenous tissue constituent information. NIR light is particularly well suited due to its relatively deep penetration in tissue and its sensitivity to deoxyhemoglobin, oxyhemoglobin, water, and lipids, which allows for quantitative measurement of physiological properties.

   Currently, nearly all optical sensing methods that use endogenous contrast are point-measurements and few are in real-time. Our lab has recently developed a novel technique for imaging endogenous tissue constituents that uses a single image capture. Moreover, with further developments in profilometry and data processing, we will be able to develop a technique capable of providing real-time images to help assess tissue viability during surgery.

   It is the goal of this work to provide the foundation for a real-time feedback imaging system that provides tissue constituent quantification.