Bulletin of the American Physical Society
Mid-Atlantic Section Fall Meeting 2020
Volume 65, Number 20
Friday–Sunday, December 4–6, 2020; Virtual
Session K03: Bio-Sensing II |
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Chair: Yuanwei Zhang, NJIT |
Sunday, December 6, 2020 11:30AM - 12:06PM |
K03.00001: Multiphoton Microscopy of Oxygen Invited Speaker: Sergei Vinogradov Molecular oxygen plays a unique role in cellular energy metabolism by serving as the terminal electron acceptor in the mitochondrial respiratory chain. Quantitative imaging of oxygen can provide invaluable information about metabolism in normal and diseased states. Two-photon phosphorescence lifetime microscopy (2PLM) enables measurements of oxygen concentration gradients in 3D with micron-scale resolution. Here we will discuss the principles of 2PLM and focus on the design of the oxygen probes, in which high two-photon absorption cross-sections are imparted by way of manipulating hidden \textit{gerade} states in fully centrosymmetric phosphorescent metalloporphyrins. We further consider three-photon absorptions in these porphyrins and identify channels and states that interfere constructively or destructively in the excitation process. The experimentally measured three-photon absorption cross-sections of some of these porphyrins are among the highest reported to date for the 1700 nm tissue transparency window. [Preview Abstract] |
Sunday, December 6, 2020 12:06PM - 12:42PM |
K03.00002: Mitochondria Imaging, Sensing and Photo-modulation Invited Speaker: Kevin Belfield Mitochondria are essential targets for study and treatment of mitochondrial dysfunction diseases such as cancer, cardiovascular and neurodegenerative diseases. Chemoresistance is one of the major challenges for cancer treatment, more recently ascribed to defective mitochondrial outer membrane permeabilization (MOMP), significantly diminishing chemotherapeutic agent-induced apoptosis. However, gaining access to the mitochondria for either long term imaging or for selective manipulation is challenging, as the hydrophobic inner membrane is a barrier limiting diffusive transport. Mitochondria penetrating peptides (MPPs) are short peptides that can be uptaken by mitochondria. We developed a novel MPP probe and evaluated its use in long term mitochondrial imaging and trafficking. The novel MPP we designed and prepared contained a six amino acid sequence, D-Argine-Phenylalanine-D-Argine-Phenylalanine- D-Argine-Phenylalanine-NH2 (rFrFrF), which was subsequently conjugated to the commercially available 6-(tetramethylrhodamine-5-(and-6)-carboxamido)hexanoic acid (TAMRA) fluorophore. The result is a novel mitochondria penetrating peptide (TAMRA-MPP). This bioconjugate exhibited low cytotoxicity, high biocompatibility, and long term persistence in mitochondria. This TAMRA-MPP conjugate is a potentially valuable long-term mitochondria tracking probe for monitoring mitochondria distribution, activities, fission, and fusion. A boron-dipyrromethene (BODIPY) chromophore-based triarylsulfonium photoacid generator (BD-PAG) was also created, and its ability to target mitochondria was demonstrated with the aim to regulate mitochondrial pH and further depolarize the mitochondrial membrane. Cell viability assays were employed to assess the BD-PAG's dark biocompatibility, and live cell fluorescence bioimaging indicated selective targeting of and accumulation in the mitochondria. A number of assays were conducted that confirmed the ability of photoactivation of BD-PAG to modulate mitochondrial pH, effecting mitochondrial membrane depolarization. Investigations with a common chemotherapeutic agent in which certain tumors develop resistance to chlorambucil was studied in combination with BD-PAG, and its photoactivation, revealed a new strategy in chemoresistance suppression. [Preview Abstract] |
Sunday, December 6, 2020 12:42PM - 12:54PM |
K03.00003: Light-responsive compounds and photo-uncaging. Yuanwei Zhang, Zhaoxiong Wan, Karthik Sambath Light-responsive protecting groups enable scientists to regulate activities of bioactive molecules in living cells upon light irradiation. The basic idea behind this technique is that molecules of interest can be inactive with photo-responsive groups, after light-triggered photo-cleavage the molecules of interest can be freed and act in an intact form. This approach has been used for drug delivery and exhibited pinpoint accuracy with light guidance as well as low off-target toxicity. However, most of the light-responsive groups show absorbability in the UV-to-blue region (300 -- 450 nm), in which the high energy radiant leads to unwanted photo-toxicity. Thus, there is a strong need to develop photo-responsive groups that can absorb light in longer wavelengths. Boron-dipyrromethene (BODIPY) derivatives were identified as one of the potential chromophores to sense light, they absorb at the visible region with high molar extinction coefficients. A new class of BODIPY-based oxime ester light-responsive compound was designed to sense green light and photo-uncage carboxylic acids. The mechanism and kinetics of the light-responsive procedure were studied. Further, we constructed a photo-uncaging drug delivery system to release valproic acid, which can inhibit the histone deacetylases and induce apoptosis in tumor cells. [Preview Abstract] |
Sunday, December 6, 2020 12:54PM - 1:06PM |
K03.00004: Tracking insect population densities and activities using an entomological stand-off optical sensor Adrien Genoud, Gregory Williams, Benjamin Thomas The most prevalent method for the survey of insect populations is based on trapping the specimens, followed by laboratory analysis. While this provides detailed information on insect characteristics such as species or sex, it suffers from important limitations: poor temporal resolution and small number of observed insects. Optical sensors constitute an exciting alternative to collect entomological data as they can observe a number insects orders of magnitude larger with a temporal resolution in the minute range. In this contribution, the results of a field campaign using a stand-off optical sensor is presented and discussed. The population density of flying insects was continuously measured for a period of three months which is, to the best of our knowledge, the longest continuous recording of insect population densities. A portable weather station allowed for the detailed study of the circadian rhythm and activities of insect populations with meteorological events and atmospheric conditions. Furthermore, with recordings starting during late Summer and ending in Fall, the collected data provides some information on the seasonal change of insect population in Secaucus New Jersey. [Preview Abstract] |
Sunday, December 6, 2020 1:06PM - 1:18PM |
K03.00005: Crystallization of hard-sphere colloids. Boris Khusid, Lei Qian Vital for a variety of industries, from 3D printing to photonics, electronics, chemicals, and pharmaceuticals, colloids also serve as an excellent model system to reveal crystallization mechanisms in condensed matter at a particle level. We present results of ongoing microgravity experiments on phase transitions in colloids of micro-spheres and micro-ellipsoids on the International Space Station. [Preview Abstract] |
Sunday, December 6, 2020 1:18PM - 1:30PM |
K03.00006: Study on the Metal-organic Frameworks for Sustainable Energy Using Various Metals and Linkers David Jaemin Choung Metal-Organic frameworks bear a huge potential for various developments in many different fields of science. This study seeks to study the stability and dynamics of different types of MOFs including UIO-66 in various conditions, such as with different metal joints or linkers with different functional groups. In this paper, Density Functional Theory (DFT), a computational chemistry, has been employed to figure out the stability and thermodynamics of different structures of MOFs, and to model the electron properties of the compound. With molecular editing programs that allow users to draw and estimate optimized energy and electrostatic potential maps for a compound, this research demonstrates the optimized geometry energy levels and fully determines the theoretical values of the structure’s atomic properties. The research focuses on increasing capacity of batteries using MOF particles as dielectrics, differing the structure of capacitors, and various combinations of inorganic metal joints and organic carbon links in order to increase the maximum capacity of batteries that can store more energy with better efficiency. Computational chemistry such as Avogadro and ChemCraft has been employed to figure out the stability and capacity of the MOF particles. [Preview Abstract] |
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