Judy Kay Hendricks

Mitochondrial Correlation Microscopy and Nanolaser Spectroscopy — New Tools for Biophotonic Detection of Cancer in Single Cells

Currently, pathologists rely on labor-intensive microscopic examination of tumor cells using century-old staining methods that can give false readings. Emerging BioMicroNano-technologies have the potential to provide accurate, realtime, high-throughput screening of tumor cells without the need for time-consuming sample preparation. These rapid, nanooptical techniques may play an important role in advancing early detection, diagnosis, and treatment of disease. In this report, we show that laser scanning confocal microscopy can be used to identify a previously unknown property of certain cancer cells that distinguishes them, with single-cell resolution, from closely related normal cells. This property is the correlation of light scattering and the spatial organization of mitochondria. In normal liver cells, mitochondria are highly organized within the cytoplasm and highly scattering, yielding a highly correlated signal. In cancer cells, mitochondria are more chaotically organized and poorly scattering. These differences correlate with important bioenergetic disturbances that are hallmarks of many types of cancer. In addition, we review recent work that exploits the new technology of nanolaser spectroscopy using the biocavity laser to characterize the unique spectral signatures of normal and transformed cells. These optical methods represent powerful new tools that hold promise for detecting cancer at an early stage and may help to limit delays in diagnosis and treatment.

NanoLaser/Microfluidic BioChip for Realtime Tumor Pathology

Through recent interdisciplinary scientific research, modern medicine has significantly advanced the diagnosis and treatment of disease. However, little progress has been made in reducing the death rate due to cancer, which remains the leading cause of death in much of the world. Pathologists routinely rely on microscopic examination of cell morphology using methods that originated over a hundred years ago. These staining methods are labor-intensive, time-consuming, and frequently in error. New micro-analytical methods1 (JBM, 1998; Harrison et al., 1993; Ramsey et al., 1995; Mauro Ferrari, Lynn Jelinski, 1994; Anderson et al., 1996; Carlson et al., 1996) for high speed (real time) automated screening of tissues and cells are critical to advancing pathology and hold the potential for improving diagnosis and treatment of cancer patients.By teaming experts in semiconductor physics, microfabrication, surface chemistry, film synthesis, and fluid mechanics with microbiologists and medical doctors, we are investigating nanostructured biochips to assess the condition of tumor cells by quantifying total protein content. This technique has the potential to quickly identify a cell population that has begun rapid protein synthesis and mitosis, characteristic of tumor cell proliferation. By incorporating microfluidic flow of cells inside the laser microcavity for the first time, we have enabled high throughput screening of cells in their native state, without need of chemical staining, in a sensitive nanodevice.

A Semiconductor Microlaser for Intracavity Flow Cytometry

Semiconductor microlasers are attractive components for micro- analysis systems because of their ability to emit coherent, intense light from a small aperture. By using a surface- emitting semiconductor geometry, we were able to incorporate fluid flow inside a laser microcavity for the first time. This confers significant advantages for high throughput screening of cells, particulates and fluid analytes in a sensitive microdevice. In this paper we discuss the intracavity microfluidics and present preliminary results with flowing blood and brain cells.

Nanosqueezed light for probing mitochondria and calcium-induced membrane swelling for study of neuroprotectants

We report a new bioMEMs nanolaser technique for measuring characteristics of small organelles. We have initially applied the method to study mitochondria, a very small (500nm to 1um) organelle containing the respiration apparatus for animal cells. Because the mitochondria are so tiny, it has been difficult to study them using standard light microscope or flow cytometry techniques. We employ a recently discovered a nano-optical transduction method for high-speed analysis of submicron organelles. This ultrasensitive detection of submicron particles uses nano-squeezing of light into photon modes imposed by the ultrasmall organelle dimensions in a submicron laser cavity. In this paper, we report measurements of mitochondria spectra under normal conditions and under high calcium ion gradient conditions that upset membrane homeostasis and lead to organelle swelling and lysis, similar to that observed in the diseased state. The measured spectra are compared with our calculations of the electromagnetic modes in normal and distended mitochondria using multiphysics finite element methods.

Reactive biomolecular divergence in genetically altered yeast cells and isolated mitochondria as measured by biocavity laser spectroscopy: rapid diagnostic method for studying cellular responses to stress and disease

We report an analysis of four strains of bakers yeast (Saccharomyces cerevisiae) using biocavity laser spectroscopy. The four strains are grouped in two pairs (wild type and altered), in which one strain differs genetically at a single locus, affecting mitochondrial function. In one pair, the wild-type rho+ and a rho0 strain differ by complete removal of mitochondrial DNA (mtDNA). In the second pair, the wild-type rho+ and a rho- strain differ by knock-out of the nuclear gene encoding Cox4, an essential subunit of cytochrome c oxidase. The biocavity laser is used to measure the biophysical optic parameter Deltalambda, a laser wavelength shift relating to the optical density of cell or mitochondria that uniquely reflects its size and biomolecular composition. As such, Deltalambda is a powerful parameter that rapidly interrogates the biomolecular state of single cells and mitochondria. Wild-type cells and mitochondria produce Gaussian-like distributions with a single peak. In contrast, mutant cells and mitochondria produce leptokurtotic distributions that are asymmetric and highly skewed to the right. These distribution changes could be self-consistently modeled with a single, log-normal distribution undergoing a thousand-fold increase in variance of biomolecular composition. These features reflect a new state of stressed or diseased cells that we call a reactive biomolecular divergence (RBD) that reflects the vital interdependence of mitochondria and the nucleus.

Biocompatible semiconductor optoelectronics

We investigate optoelectronic properties of integrated structures comprising semiconductor light-emitting materials for optical probes of microscopic biological systems. Compound semiconductors are nearly ideal light emitters for probing cells and other microorganisms because of their spectral match to the transparency wavelengths of biomolecules. Unfortunately, the chemical composition of these materials is incompatible with the biochemistry of cells and related biofluids. To overcome these limitations, we investigate functionalized semiconductor surfaces and structures to simultaneously enhance light emission and the flow of biological fluids in semiconductor microcavities. We have identified several important materials problems associated with the semiconductor/biosystem interface. One is the biofluid degradation of electroluminescence by ionic diffusion into compound semiconductors. Ions that diffuse into the active region of a semiconductor light emitter can create point defects that degrade the quantum efficiency of the radiative recombination process. In this paper we discuss ways of mitigating these problems using materials design and surface chemistry, and suggest future applications for these materials.

Semiconductor Microcavity Laser Spectroscopy of Intracellular Protein in Human Cancer Cells

The speed of light through a biofluid or biological cell is inversely related to the biomolecular concentration of proteins and other complex molecules comprising carbon- oxygen double bonds that modify the refractive index at wavelengths accessible to semiconductor lasers. By placing a fluid or cell into a semiconductor microcavity laser, these decreases in light speed can be sensitively recorded in picoseconds as frequency red-shifts in the laser output spectrum. This biocavity laser equipped with microfluidics for transporting cells at high speed through the laser microcavity has shown potential for rapid analysis of biomolecular mass of normal and malignant human cells in their physiologic condition without time-consuming fixing, staining, or tagging.

Mitochondrial correlation as a biophotonic marker for detecting cancer in a single cell

Currently, pathologists rely on labor-intensive microscopic examination of tumor cells using century-old staining methods that can give false readings. Emerging BioMicroNanotechnologies have the potential to provide accurate, realtime, high throughput screening of tumor cells without invasive chemical reagents. These techniques are critical to advancing early detection, diagnosis, and treatment of disease. Using our award-winning Hyperspectral Inceptor to rapidly assess the properties of cells flown through a micro/nano semiconductor device, we discovered a method to rapidly assess the health of a single mammalian cell. The key discovery was the elucidation of biophotonic differences in normal and cancer cells by using intracellular mitochondria as biomarkers for disease. This technique holds promise for detecting cancer at a very early stage and could nearly eliminate delays in diagnosis and treatment.

Detecting cancer quickly and accurately

We present a new technique for high throughput screening of tumor cells in a sensitive nanodevice that has the potential to quickly identify a cell population that has begun the rapid protein synthesis and mitosis characteristic of cancer cell proliferation. Currently, pathologists rely on microscopic examination of cell morphology using century-old staining methods that are labor-intensive, time-consuming and frequently in error. New micro-analytical methods for automated, real time screening without chemical modification are critically needed to advance pathology and improve diagnoses. We have teamed scientists with physicians to create a microlaser biochip (based upon our R&D award winning bio- laser concept) which evaluates tumor cells by quantifying their growth kinetics. The key new discovery was demonstrating that the lasing spectra are sensitive to the biomolecular mass in the cell, which changes the speed of light in the laser microcavity. Initial results with normal and cancerous human brain cells show that only a few hundred cells -- the equivalent of a billionth of a liter -- are required to detect abnormal growth. The ability to detect cancer in such a minute tissue sample is crucial for resecting a tumor margin or grading highly localized tumor malignancy.

Quantum Squeezed Light for Probing Mitochondrial Membranes and Study of Neuroprotectants

We report a new nanolaser technique for measuring characteristics of human mitochondria. Because mitochondria are so small, it has been difficult to study large populations using standard light microscope or flow cytometry techniques. We recently discovered a nano-optical transduction method for high-speed analysis of submicron organelles that is well suited to mitochondrial studies. This ultrasensitive detection technique uses nano-squeezing of light into photon modes imposed by the ultrasmall organelle dimensions in a semiconductor biocavity laser. In this paper, we use the method to study the lasing spectra of normal and diseased mitochondria. We find that the diseased mitochondria exhibit larger physical diameter and standard deviation. This morphological differences are also revealed in the lasing spectra. The diseased specimens have a larger spectral linewidth than the normal, and have more variability in their statistical distributions.