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Maria R Hepel

SUNY: Potsdam, Chemistry, Faculty Member

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My research has recently been focused on developing novel nanobiosensors and theranostic targeted drug delivery nanocarriers for novel nanomedicine applications. My research group designed a range of piezoimmunosensors for various biomarkers, toxicants, and pollutants, as well as new surface-enhanced Raman scattering probes based on plasmonic nanocarriers immobilized on a gold electrode. We are also developing biosensors based on DNA with electrochemical redox or fluorescent labels, enabling studies of DNA damage by chemotherapeutic drugs and toxicants. In addition, we studied intercalation materials such as WO3 and photoelectrochemical degradation of azo dyes.

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Papers by Maria R Hepel

Functional Gold Nanoparticles for Biointerfaces

Functional Nanoparticles for bioanalysis, nanomedicine, and Bioelectronic Devices Vol. 1, 2012

The state-of-the-art of the design of multi-functional nanoparticles for biomedical applications ... more The state-of-the-art of the design of multi-functional nanoparticles for biomedical applications is presented and discussed with emphasis on nanoparticle drug carriers, gene delivery, photodynamic therapy, and image enhancers for diagnostic imaging, including MRI, CT scan, ultrasonic, photoacoustic, and surface-enhanced Raman scattering techniques. The multi-modality, as defined by theranostics, whereby the diagnostic enhancement capabilities are combined with therapeutic action, is the key feature of nanoparticle applications in nanomedicine. The important requirement in these applications is the high selectivity in cell targeting, especially as regards to the tumor cells, designated to be destroyed by highly cytotoxic drugs unloaded from the nanoparticle nanocarriers. The biocompatibility issues are discussed in view of the necessity of protecting healthy cells. For this purpose, the polyamine-coated gold nanoparticles have been reviewed and the adsorption hyper-Langmuirian model has been introduced. The formation of nanostructures from nanoparticle building blocks is also discussed.

Electrochemical Science Advances

Electrochemical Science Advances, 2022

Supercapacitors are a new brand of high-performance nanoengineered devices that match the high ca... more Supercapacitors are a new brand of high-performance nanoengineered devices that match the high capacity of batteries for electric energy storage with the ability of dry capacitors for ultra-fast charging or discharging rates. Thus, supercapacitors are capable of simultaneously providing the high energy-density and high power-density, demanded in a plethora of biosensors and portable elec

High Power-Density WO 3-x -Grafted Corannulene-Modified graphene nanostructures for Micro-Supercapacitors

Journal of Electroanalytical Chemistry, 2023

The emergence of nanotechnology and development of new methods of nanoengineering novel materials... more The emergence of nanotechnology and development of new methods of nanoengineering novel materials have enabled to design supercapacitors, new devices filling the niche between the high energy-density electrochemical batteries and the high power-density dry capacitors. Thanks to the nanoengineering, new devices combining the unique properties of electrochemical double-layer capacitance with high storage capability of pseudocapacitance materials could became a reality. A special niche in these applications is for micro-supercapacitors, which can drive miniature sensors and implantable biodevices, requiring fast remote charging and high energy density packed in a small volume. In this work, the micro-supercapacitors were fabricated using WO 3-x nanoparticles immobilized on rGO nanosheets to increase the carbon nanoform double-layer capacitance by adding very high pseudocapacitance of WO 3-x. To improve the attachment of WO 3 to the carbon support and enhance the graphene matrix conductance, grafting of WO 3 nuclei onto the GO defect sites was employed by electrochemical processing and nanoparticle growth, followed by the electroreduction of unprotected oxidation sites of GO to form a highly-conductive reduced graphene oxide (rGO) support. Further protection of rGO nanosheets from stacking interactions was also necessary. It was achieved by modifying graphene sheets with corannulene (CORA) which is a C 20 H 10 polyaromatic hydrocarbon (PAH) molecule forming a cup (or: Bucky bowl) structure. We have found that corannulene can efficiently separate the rGO nanosheets in more hydrophobic locations of rGO where WO 3-x nanoforms are missing. The chemical structure, morphology, and electrochemical properties of hybrid materials used for designing the micro-supercapacitor devices were characterized by Raman spectroscopy (RS), atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), infra-red spectroscopy (FTIR), electrochemical quartz crystal nanogravimetry (EQCN), cyclic voltammetry (CV), as well as potential-pulse and current-pulse charging/discharging characteristics. The supercapacitor properties of the proposed WO 3 ,CORA/rGO devices were favorable compared with those for mono plate graphene (MPG) and laser-induced graphene (LIG) MSCs.

Cancer-Targeted Controlled Delivery of Chemotherapeutic Anthracycline Derivatives Using Apoferritin Nanocage Carriers

Int. J. Mol. Sci, 2021

This article is an open access article distributed under the terms and conditions of the Creative... more

Quantum conductance of monatomic Ni nanobridges

Electrochimica Acta 51(2006) 5811-5824, 2006

The quantum conductance phenomena in narrow metal nanobridges were investigated. The nanobridge d... more The quantum conductance phenomena in narrow metal nanobridges were investigated. The nanobridge devices with small atomic-wide gap were formed by a novel controlled electroplating method on a nanolithographed quartz wafer. The metallic contact nanowires were grown across the gap by field evaporation. The field-induced formation and field-stabilization of monatomic Ni nanobridges are described. Thus formed Ni nanowires appeared to be unstable in the absence of electric field and disassembled quickly under no field conditions. The minimum quantum conductance associated with monatomic constriction in the nanobridge was observed. Exceptionally stable monatomic quantum nanobridges (QNB) were obtained by chemical treatment. They were investigated in the dry state and in the electrolyte solutions. The quantum conductance with zero temperature coefficient was observed at low electric field strength E (bias voltage |V b | < 0.3 V) but thermionic conductance dominated at higher E (|V b | > 0.8 V) leading to the conductance increase with temperature, opposite to the behavior of a bulk Ni metal. The mechanism of the observed phenomenon is presented. To gain further insights into the thermionic barrier formation in QNB, we have performed quantum mechanical calculations, using semi-empirical method, for model Ni nanobridge atom clusters (base:nanowire:base = 6:n:6 atoms, with n = 1-5). They have shown that in longer joining nanowires (n > 1) the lowest unoccupied molecular orbitals (LUMO) are predominantly concentrated over base electrodes (reservoirs) rather than over the nanowire constriction, while the short (monatomic) nanowires are densely populated with low lying LUMO's. The results of calculations suggest also that the location of the quantum confinement (the constriction) may not necessarily be at the nanowire center (as generally assumed) but rather at the joints of nanowire with base electrodes where the wire width is the lowest.

Novel dynamic effects in electrocatalysis of methanol oxidation on supported nanoporous TiO 2 bimetallic nanocatalysts

Electrochimica Acta 52 (2007) 5529-5547, 2007

New dynamic aspects of the catalysis of methanol oxidation reaction (MOR) have been studied using... more New dynamic aspects of the catalysis of methanol oxidation reaction (MOR) have been studied using quantum mechanical calculations applied to the support-catalyst cluster interactions and surface diffusivity of adsorbed intermediates. For very small catalyst-support clusters, we have found a strong enhancement of the ligand effect for bimetallic catalysts of the type Pt n M m attributed to the decreased local density of states near the Fermi level of Pt atoms neighboring the additive metal atom M. This enhancement results in a decreased barrier for surface diffusion of adsorbed CO ad through the cooperative diffusion mechanism, based on structural relaxation of the catalyst-support cluster, proposed in this work. The strong ligand effect dominates over the Schwoebel potential and trapping well effects, being responsible for accumulation of poisoning intermediates at step sites on the catalyst surface and gradual decrease of catalytic activity with decreasing size of catalyst nanoparticles. The lattice relaxation and strong ligand effects in small catalyst-support clusters lead to lower adsorption energy for CO ad and thus, to higher reactivity and mobility of reactants and intermediates. The experimental investigations included submonolayer films of bi-functional catalysts (PtRu, PtFe) deposited on novel nanostructured supporting materials, designed with the goal of achieving high variability of their electronic and chemical properties to influence the catalytic activity of sub-monolayer catalyst. The mesoscopic TiO 2 supporting film formation was investigated using EQCN, pulse voltammetric and AFM techniques. The conditions for the formation of monodispersed TiO 2 nanoparticles with regular nanopores (nanotubes), 20-80 nm in diameter, were described. It follows from EQCN and voltammetric measurements and AFM image analysis that the nanopores are formed by a dissolution-precipitation mechanism. The catalysts, Pt and PtRu, deposited on supporting nanoporous TiO 2−x films, were used to study MOR. A lower poisoning effect for cluster PtRu on a TiO 2−x support film than that for unsupported PtRu or bare Pt catalysts has been observed. These effects have been attributed to differences in CO ad binding energy and lowering of activation energy for surface mobility leading to a more facile 2D diffusion of CO ad from Pt sites to Ru and the supporting TiO 2−x. The substrate-catalyst interactions were further investigated using quantum mechanical calculations performed for a model TiO 2 nano-ring (representing an orifice of a TiO 2−x nanotube studied experimentally) with adlayers of Pt, Ru and Fe catalysts. We have found unusually strong electron delocalization effects for Pt 2 Fe 2 clusters on (TiO 2) 4 as compared to (TiO 2−x) 4 Pt 2 Ru 2. We have also analyzed various states in surface diffusion of CO ad on bimetal clusters supported on (TiO 2) n and observed considerable dynamic widening of metal-to-metal atom distances induced by CO adsorption (up to 9% for Pt-Pt distance and up to 15% for Fe-Fe distance). We propose that this new dynamic effect leading to cooperative surface diffusion may be further explored in designing novel nanoparticle catalysts.

Magneto-Plasmonic Nanoparticle Grid Biosensor with Enhanced Raman Scattering and Electrochemical Transduction for the Development of Nanocarriers for Targeted Delivery of Protected Anticancer Drugs

by Maria R Hepel and Hoda Ilkhani

Nanomaterials, 2021

This article is an open access article distributed under the terms and conditions of the Creative... more

Nanostructured SERS-electrochemical biosensors for testing of anticancer drug interactions with DNA

Biosensors and Bioelectonics, 2016

Widely used anti-cancer treatments involving chemotherapeutic drugs result in cancer cell damage ... more Widely used anti-cancer treatments involving chemotherapeutic drugs result in cancer cell damage due to their strong interaction with DNA. In this work, we have developed laboratory biosensors for screening chemotherapeutic drugs and to aid in the assessment of DNA modification/damage caused by these drugs. The sensors utilize surface-enhanced Raman scattering (SERS) spectroscopy and electrochemical methods to monitor sensory film modification and observe the drug-DNA reactivity. The self-assembled monolayer protected gold-disk electrode (AuDE) was coated with a reduced graphene oxide (rGO), decorated with plasmonic gold-coated Fe 2 Ni@Au magnetic nanoparticles functionalized with doublestranded DNA (dsDNA), a sequence of the breast cancer gene BRCA1. The nanobiosensors AuDE/SAM/ rGO/Fe 2 Ni@Au/dsDNA were then subjected to the action of a model chemotherapeutic drug, doxorubicin (DOX), to assess the DNA modification and its dose dependence. The designed novel nanobiosensors offer SERS/electrochemical transduction, enabling chemically specific and highly sensitive analytical signals generation. The SERS measurements have corroborated the DOX intercalation into the DNA duplex whereas the electrochemical scans have indicated that the DNA modification by DOX proceeds in a concentration dependent manner, with limit of detection LOD ¼8 mg/mL (S/N ¼3), with semilog linearity over 3 orders of magnitude. These new biosensors are sensitive to agents that interact with DNA and facilitate the analysis of functional groups for determination of the binding mode. The proposed nanobiosensors can be applied in the first stage of the drug development for testing the interactions of new drugs with DNA before the drug efficacy can be assessed in more expensive testing in vitro and in vivo.

Nanostructured SERS-electrochemical biosensors for testing of anticancer drug interactions with DNA

Biosensors and Buioelectronics, 2016

Widely used anti-cancer treatments involving chemotherapeutic drugs result in cancer cell damage ... more Widely used anti-cancer treatments involving chemotherapeutic drugs result in cancer cell damage due to their strong interaction with DNA. In this work, we have developed laboratory biosensors for screening chemotherapeutic drugs and to aid in the assessment of DNA modification/damage caused by these drugs. The sensors utilize surface-enhanced Raman scattering (SERS) spectroscopy and electrochemical methods to monitor sensory film modification and observe the drug-DNA reactivity. The self-assembled monolayer protected gold-disk electrode (AuDE) was coated with a reduced graphene oxide (rGO), decorated with plasmonic gold-coated Fe 2 Ni@Au magnetic nanoparticles functionalized with doublestranded DNA (dsDNA), a sequence of the breast cancer gene BRCA1. The nanobiosensors AuDE/SAM/ rGO/Fe 2 Ni@Au/dsDNA were then subjected to the action of a model chemotherapeutic drug, doxorubicin (DOX), to assess the DNA modification and its dose dependence. The designed novel nanobiosensors offer SERS/electrochemical transduction, enabling chemically specific and highly sensitive analytical signals generation. The SERS measurements have corroborated the DOX intercalation into the DNA duplex whereas the electrochemical scans have indicated that the DNA modification by DOX proceeds in a concentration dependent manner, with limit of detection LOD ¼8 mg/mL (S/N ¼3), with semilog linearity over 3 orders of magnitude. These new biosensors are sensitive to agents that interact with DNA and facilitate the analysis of functional groups for determination of the binding mode. The proposed nanobiosensors can be applied in the first stage of the drug development for testing the interactions of new drugs with DNA before the drug efficacy can be assessed in more expensive testing in vitro and in vivo.

Ligand exchange effects in gold nanoparticle assembly induced by oxidative stress biomarkers: Homocysteine and cysteine

This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright

Iron Uptake and Release from Ferritin-Modified Gold Electrodes

ECS Meeting Abstracts, 2011

not Available.

Electrochemical quartz crystal microbalance studies of partially oxidized tetracyanoplatinum salts

Journal of Materials Chemistry, 1996

ABSTRACT

Nanostructural Effects in Designing Novel Electrocatalysis for Fuel Cells

ECS Meeting Abstracts, 2007

not Available.

Nanotemplating of Deposition Processes

ECS Meeting Abstracts, 2005

Nanoscale devices with individually addressed elements of arrays have been extensively studied si... more Nanoscale devices with individually addressed elements of arrays have been extensively studied since they bring a critical step in design of integrated high speed and high capacity architectures for computing and chemical and biological sensor development. The active elements, such as molecular fieldeffect transistors, must have a massively expanded connectivity realized by nanowires with high electron mobility. Various concepts in nanowiring have been explored including metal, carbon nanotubes, conductive polymers, etc. We have studied molecularly templated deposition of metals in the form of nanowires. Templates were formed by microcontact printing or by micromechanical manipulation of adsorbed organic molecules using nanoactuators. The surface accessibility through molecular templates was tested using adatom probe method. The nanowires deposited by molecular templating were subsequently imaged using AFM and STM. The method allowed also deposit nanostructured metal oxide semiconductors, such as TiO2 and WO3, and conductive polymers (PPy) in small spots, 100500 nm. The nanowires and conductive polymer spots can be deposited on top of Si wafer structures forming photosensors or memory devices. The molecular templating employed was based on studies of conformational transitions in thin films of biomolecules and comparative interactions with different metals. The aim of this project has been to develop an array of microsensors able to detect and quantify a range of pollutants and toxic substances. We have succeeded with large area highly specific sensors for PCB and herbicide 2,4-D, based on monoclonal antibodies, and developed sensors for heavy metals.

Transient conformation changes of albumin adsorbed on gold piezoelectrodes

Electrochimica Acta, Sep 1, 2005

The adsorption of bovine serum albumin (BSA) on Au piezoelectrodes was investigated using Electro... more The adsorption of bovine serum albumin (BSA) on Au piezoelectrodes was investigated using Electrochemical Quartz Crystal Nanobalance (EQCN), redox ion probe, and tapping-mode AFM techniques. The high ionic conductance of Au|BSA films, owing to the presence of voids, allowed for extensive studies of the templated deposition of cadmium and electrocatalytic nitrate reduction processes. Changes in BSA conformation in the adsorbed state were found to occur on completion of Cd-upd formation in the presence of nitrate ions. The conformational transition was reversible and BSA film integrity was preserved, as confirmed in multiple scan experiments and by carrying out Quartz Crystal Immittance (QCI) measurements. No change in the resonance admittance modulus versus frequency was observed. We have found that triggering of BSA conformational transition is not associated with bulk-Cd 0 nucleation and growth. Mechanistic considerations have led to the conclusion that BSA conformation changes are due to BSA adjustment to the changing electric field distribution in Au|BSA film associated with formation of surface complexes of partially charged Cd-upd with NO 2 − changing electrode charge and local pH increase caused by the electrocatalytic nitrate ion reduction. This mechanism is corroborated by the fact that in other Cd(II) solutions, not containing NO 2 − anions, conformational transitions in Au|BSA films were not observed.

Study of the Initial Stages of Anodic Oxidation of Polycrystalline Silver in KOH Solutions

Journal of The Electrochemical Society, Jun 1, 1984

Reproduction in whole or in part is permitted for any purpose of the United States Government Thi... more Reproduction in whole or in part is permitted for any purpose of the United States Government This document has been approved for public release Kand sale; its distribution is unlimited C4 0-J~8 40222061 !ECUflITYI CLASSIFICATION OF TH4IS PAGE (Ufu, Date Entered) REPOT DCUMNTATON AGEREAD INSTRUCTIONS REPOR DOCMENTTION AGE EFOR COMPLETING FORM I. REOR NUMBER. GOV? ACCESSION NO. S. RECIPIENT'$ CATALOG NUMBER 4. TITLE (and Subttl) a. TYPE OF REPORT a PERIOD COVERED STUDY OF THE INITIAL STAGES OF ANODIC OXIDATION OF POLYCRYSTALLINE SILVER IN KOH SOLUTIONS_____________ 6. PERFORMING ORG. REPORT NUMBER 7. AUTI4OR() C ONTRAC 0N GRANT UMRe) MARIA REPEL 1000 14-81-K-0399 MICIA TOHKIEWICZ 9. PERFORMING ORGANIZATION NAME AND ADDRESS 0. PROGA L N POROJE[CT. TASK AR& WORKUNINMER PHYSICS DEPARTMENT BROOKLYN COLLEGE OF CUNT ER-628-765 lggfiffvV__Uv 11111_______________ 11. CON0TROLLING OFFICE NAME AND AIDDRESS 12. REPORT DATE

Nanostructured SERS-electrochemical biosensors for testing of anticancer drug interactions with DNA

Biosensors and Bioelectronics, Jun 1, 2016

Widely used anti-cancer treatments involving chemotherapeutic drugs result in cancer cell damage ... more Widely used anti-cancer treatments involving chemotherapeutic drugs result in cancer cell damage due to their strong interaction with DNA. In this work, we have developed laboratory biosensors for screening chemotherapeutic drugs and to aid in the assessment of DNA modification/damage caused by these drugs. The sensors utilize surface-enhanced Raman scattering (SERS) spectroscopy and electrochemical methods to monitor sensory film modification and observe the drug-DNA reactivity. The self-assembled monolayer protected gold-disk electrode (AuDE) was coated with a reduced graphene oxide (rGO), decorated with plasmonic gold-coated Fe2Ni@Au magnetic nanoparticles functionalized with double-stranded DNA (dsDNA), a sequence of the breast cancer gene BRCA1. The nanobiosensors AuDE/SAM/rGO/Fe2Ni@Au/dsDNA were then subjected to the action of a model chemotherapeutic drug, doxorubicin (DOX), to assess the DNA modification and its dose dependence. The designed novel nanobiosensors offer SERS/electrochemical transduction, enabling chemically specific and highly sensitive analytical signals generation. The SERS measurements have corroborated the DOX intercalation into the DNA duplex whereas the electrochemical scans have indicated that the DNA modification by DOX proceeds in a concentration dependent manner, with limit of detection LOD=8µg/mL (S/N=3), with semilog linearity over 3 orders of magnitude. These new biosensors are sensitive to agents that interact with DNA and facilitate the analysis of functional groups for determination of the binding mode. The proposed nanobiosensors can be applied in the first stage of the drug development for testing the interactions of new drugs with DNA before the drug efficacy can be assessed in more expensive testing in vitro and in vivo.

Intervention of glutathione in pre-mutagenic catechol-mediated DNA damage in the presence of copper(II) ions

Mutation Research: Fundamental And Molecular Mechanisms Of Mutagenesis, Jul 1, 2012

The catechol-mediated DNA damage in the presence of Cu(II) ions involves oxidation of guanine to ... more The catechol-mediated DNA damage in the presence of Cu(II) ions involves oxidation of guanine to 8-oxoguanine (8-oxoG) and DNA strand scission. It proceeds through the reactive oxygen species (ROS) generation. The mutagenicity of 8-oxoG lesions is due to its miscoding propensity reflected in GC→TA transversion taking place during the DNA repair process. To gain new insights into the nature of catechol-mediated DNA damage and its prevention, we have investigated the changes in DNA melting characteristics and 8-oxoG formation as the indicators of DNA damage in a model calf-thymus DNA system. A novel fluorescence method for DNA melting temperature determination, based on DAPI fluorescent-probe staining, has been proposed. The DNA melting-onset temperature has been found to be more sensitive to DNA damage than the standard melting temperature due to the increased width of the melting transition observed in oxidatively damaged DNA. We have found that the efficiency of Fenton cascade in generating DNA-damaging ROS is higher for catechol than for GSH, two strong antioxidants, mainly due to the much longer distance between ROS-generating radical group in GS to nucleobases than that of semiquinone radical group to nucleobases (2.1nm vs. 0.27nm), making the ROS transport from GSH an order of magnitude less likely to damage DNA because of short lifetime of HO radicals. The antioxidant and DNA-protecting behaviors of GSH have been elucidated. We have found that the redox potential of GSH/GSSG couple is lower than that of catechol/semiquinone couple. Hence, GSH keeps catechol in the reduced state, thereby shutting down the initial step of the catechol-mediated Fenton cascade. The catechol-induced DNA damage in the presence of Cu(II) ions has also been confirmed in studies of ON-OFF hairpin-oligonucleotide beacons.

“Molecular Beacon”-Based Fluorescent Assay for Selective Detection of Glutathione and Cysteine

Analytical Chemistry, Jan 6, 2011

We report on the development of a fluorescence turn-on &amp;amp;amp;amp;amp;amp;amp;amp;amp;a... more We report on the development of a fluorescence turn-on &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;molecular beacon&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; probe for the detection of glutathione (GSH) and cysteine (Cys). The method is based on a competitive ligation of Hg(2+) ions by GSH/Cys and thymine-thymine (T-T) mismatches in a DNA strand of the self-hybridizing beacon strand. The assay relies on the distance-dependent optical properties of the fluorophore/quencher pair attached to the ends of the molecular beacon DNA strand. In a very selective coordination of Hg(2+) to GSH/Cys, the fluorophore/quencher distance increases concomitantly with the dehybridization and dissociation of the beacon stem T-Hg(2+)-T due to the extraction of Hg(2+) ions. This process results in switching the molecular beacon to the &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;on&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; state. The concentration range of the probe is 4-200 nM with the limit of detection (LOD) of 4.1 nM for GSH and 4.2 nM Cys. The probe tested satisfactorily against interference for a range of amino acids including sulfur-containing methionine.

Influence of Antioxidants on DNA Damage Induced by Catechol

Meeting abstracts, 2011

not Available.