טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentOlszakier Shunit
SubjectIntracellular Labelling of Selected Neurons Utilizing
MR-Visible Nanoparticle Imaging
DepartmentDepartment of Medicine
Supervisors Professor Itamar Kahn
Professor Lilac Amirav


Abstract

A central goal of diagnostic medical imaging is to characterize the cellular integrity of brain cells when degenerative processes are on-going but prior to massive cell death that results in gross atrophy. Magnetic resonance imaging (MRI) is a commonly used method in humans and animals, which is able to measure integrity of an organic tissue. Current intrinsic contrast, however, cannot distinguish between the intra and extra-cellular environments. Bio functionalization high performance Magneto-fluorescent materials are established as emerging hybrid intracellular labeling markers that displays unique properties in advanced biological applications. In my thesis, I developed a novel class of nanoparticles that are dually compatible in both MRI and optical light microscopy (LM), allowing high contrast imaging of the intracellular environment. My research focuses on developing a platform to characterize and optimize these particles to become an effective contrast agent for both, MRI and LM, imaging of neurons in intracellular environment. Ultra-small superparamagnetic Iron Oxide nanoparticles (USPIOs) exhibit strong magnetization that induces microscopic field inhomogeneity in the presence of an external magnetic field. Due to their small size, USPIOs are optimal for internalization into cells with minimal interference in biological processes. Testing the effects on cells at the microscopic level required additional labeling of the USPIOs, such as a fluorescent marker. Quantum dots are excellent fluorescent components thanks to their high temporal stability and resistance to photo -bleaching compared with dyes. Hence, I combined USPIOs with CdSe@CdS core, which are a subclass of quantum dots. Thus magneto-fluorescent nanoparticles were designed with a unique morphology that prevented undesirable interactions within the hybrid that could abrogate the respective properties. Syntheses of these magneto-fluorescent nanoparticles yield a strong bi-functional nontoxic contrast agent. In a series of experiments I demonstrate the viability of these nanoparticles for intracellular characterization using MRI and optical LM. Our results suggest the feasibly of using intracellular contrast agent for imaging cellular integrity. We developed a method to validate the efficacy and compatibility of Magneto Fluorescence Hybrid Nano Particles (MFHNP) to label in vitro and in vivo biological tissue, which are of particle interest in neuro science applications. MFHNP combines the labeling properties of magnetic resonance imaging (MRI) covering large volumes and optical light microscopy (LM) with high spatial resolution. It is fundamental to characterize and optimize the virtues of hybrid labeling markers to act as a superb MRI contrast agent with, high fluorescent yield in a well-defined optical spectrum. Yet the nano particles should be bio-compatible and nontoxic, penetrate and reach the targeted region of interest with an accurate concentration, and have a long-term stability. We present a thorough step by step iterative method to validate and qualify the efficiency, competence, environmental adeptness and virtues of the hybrid labeling markers. This method is demonstrated in various in vivo cultures, in vitro, in life cell and small animals.