Presentation on theme: "SERS Biosensor for Endocrine Disruption Biomarker: Vitellogenin"— Presentation transcript:
1 SERS Biosensor for Endocrine Disruption Biomarker: Vitellogenin Sachin Kumar SrivastavaMentor: Prof. Ibrahim AbdulhalimDepartment of Electro-optic Engineering, &Ilse Katz Institute for Nanoscale Science and Technology,Ben-Gurion University of the Negev, Be’er Sheva, Israel
2 OutlineIntroductionRaman-/Surface Enhanced Raman- Spectroscopy (SERS)BiosensorEndocrine Disruption CompoundsNano-Sculptured Thin Films (n-STFs): Optimization of performanceFabrication : Steps involved in developing the sensorResults: Sensing and other characterizationsSummary
3 Raman Spectroscopy Indian Physicist: C. V. RAMAN "A small fraction of sunlight passing through a transparent medium is scattered in all directions, with a different wavelength than the incident radiation. These shifts depend upon the chemical structure of the molecules.“ "A new radiation", Indian J. Phys.,2(1928)387.Nobel prize in Physics : 1930Rayleigh ScatteringRaman ScatteringLowest Electronic StateVirtual levelsAnti-StokesStokesRayleigh Scattering:ElasticRaman Scattering:Inelasticv3v2v1v01 in 107 photons is scattered inelasticallyGround State
4 Steps of Raman development ‘Fingerprint’ of molecular bonds and crystalline structureVery low cross-section: Applications in real life are hinderedSteps of Raman development• Laser applications – Dramatically improved power of excitation and Raman signal• SERS effect – Enhanced intensities up to factors of 108-9• Raman microscope – Decreased probe volume (light spot diameter below 1 μm)What is SERS?Large local field enhancement on rough metallic surfaces due to plasmonic and charge transfer enhancement mechanismsPlasmonic NanostructuresIncident lightEnhanced Raman ScatteringAdsorbed moleculesSERS SubstrateNanosculptured Thin Films (nSTFs)
5 Biosensor Sensor Bio-sensor A device having the role of converting a change in one physical parameter into a change in magnitude of a second different parameter which can be measured more conveniently and perhaps more accurately.Bio-sensorA biosensor is a self-contained integrated device that is capable of providing specific quantitative or semi-quantative analytical information using a biological recognition element which is in direct soatial contact with a transduction element (IUPAC, 1996)Any device that uses specific biochemical reactions to detect chemical compounds in biological samples.
6 Components of a Biosensor / OpticalDetectorMolecule imprinted gel matrixChemical interactionSPR/SERS etc
7 Basic Characteristics of a Biosensor nm1<nm2WavelengthSENSITIVITY: Response per unit analyte numerical value.DETECTION ACCURACY: How accurate the measurement is?LIMIT OF DETECTION: What is the minimum numerical valueof the parameter which can be sensed?SELECTIVITY: Interference from other factors must beminimized for obtaining correct results5. RESPONSE TIME: Time necessary for having about 95% of the response.6. REUSABILITY: Can the sensor be used again and again?SHELF LIFE: What happens to the performance when kept for long timeSENSING VOLUME: Volume of analyte required for sensingRANGE OF OPERATION: What is the working range of the sensor
8 Endocrine System General Functions of Hormones Bond 1979, Biology of Fishes
9 Endocrine Disruptors Suspected Endocrine Disruptors Metals (Pb, As, Hg, Ni, Cd)Suspected Endocrine DisruptorsIndustrial Chemicals(Bisphenol A)Synthetic and Natural Hormones(Phytoestrogens)Pharmaceutical Drugs(Corticosteroids)Pesticides, Herbicides etc.(DDT )Personal Care Products(Phthalates, Benzaldehyde)Growth inhibitionDiabetesVg : Egg yolk protein in aquatic females, excreted during sexElevated amounts: A sign of estrogenic contamination of aquatic environment.Representative of a kind ofpollution in water/aquatic species
11 Optimization of Performance SERS from 4-Aminothiophenol (4-ATP) adsorbed at the n-STFHighest SERS signal due to plasmons couplingMutual interaction between the EM fields of the localized surface plasmons (LSPs) at the neighbouring nanorodsEffective electromagnetic field of the LSPs in the voidsField in voids decreases with increase in porosityThe number of adsorbed molecules increases, however.Trade off between the enhancement due to rods and voidsMaximum 30% porosity
16 Control Experiments Reusability and Repeatability Confirmation for the specificity of the sensor to vitellogenin.Another similar protein called Fetuin was used for study.Reusability and RepeatabilityA number of sensor chips were prepared and experiments were performedover a period of three months at different days, times and ambient conditionsThe sensor surface was regenerated by immersing in 50mM glycine buffer for2 minutes in between two sensing events.Each chip was used at least three times for full sample concentration range toensure the repeatability and reusability.
18 SummaryA highly sensitive, fast Vg sensor chip utilizing SERS has been fabricatedSERS can be used for sensing of bigger molecules in non-direct mode of sensingVitellogenin concentrations as small as 5pg/ml can be detectedThe sensor is specific to Vg only.The repeatability, reusability and shelf life of the sensor are reasonably goodFor more detailed discussion of the presented results, please seeSERS Biosensor Using Metallic Nano-Sculptured Thin Films for the Detection of Endocrine Disrupting Compound Biomarker Vitellogenin, SMALL (Wiley), DOI: /smll
19 Other Contributors/Co-authors Dr. Atef Shalabney,Laboratoire des Nanostructures, ISIS - Institut de Science et d'Ingénierie Supramoléculaires,Université de Strasbourg, 8 allée Gaspard Monge Strasbourg, CedexDr. Isam Khalaila,The Avram and Stella Goldstein-Goren Department of Biotechnology Engineering, Ben Gurion University, Beer Sheva-84105, IsraelDr. Christoph Grüner and Prof. Bernd RauschenbachLeibniz Institute of Surface Modification, Permoserstrasse 15, Leipzig and University Leipzig, Institute for Experimental Physics II, Linnéstr.5, Leipzig, GermanyProf. Ibrahim AbdulhalimDepartment of Electro optic Engineering and Ilse Katz Institute for Nanoscale Sciences and Technology, Ben Gurion University of the Negev, Beer Sheva 84105, Israel &School of Materials Science and Engineering, Nanyang Technological University, , Singapore
20 Thank You Acknowledgements Council of Higher Education of the Government of the State of Israel for PBC post-doctoral fellowshipSingapore National Research Foundation (CREATE programme)German Excellence Initiative of the Deutsche Forschungs Gemeinschaft (DFG).Thank You
24 Dipole moment in a molecule α0 - molecule equilibrium polarizabilityE0 - maximum electric fieldν0 & ν - excitation and vibrational frequency, respectivelyrmax - maximum vibrational amplitude’Modulation’ of linear optical polarizabiliy due to presence of internal vibrationsIntensityValues at~ 1500 cm-1I(l) >> IS >> IaS1 >> >> 10-9
25 Mechanism of Enhancement in SERS Electromagnetic MechanismChemical MechanismElectromagnetic MechanismInduced dipole moment in a moleculeThe molecular polarizability increases due to the formation of charge transfer (CT) metal-molecule complex. The CT band is in resonance with both the incident and scattered light.The local electric field experienced by the adsorbed molecule increases due to excitation of localized surface plasmons by both the incident and scattered photonsEnhancement Contribution:Enhancement Contribution:SERS depends on the local field to the fourth power ( ) in the vicinity ofan adsorbate molecule.It is a small range effect (~ 2-3 nm).
26 Endocrine System Endocrine Disruptors Possible Factors Endocrine system is an ensemble of glands which secrete different types of hormones directly into the blood stream to maintain homeostasis. The endocrine system regulates many vital processes in a living organism, such as development, growth, reproduction and metabolism.Endocrine DisruptorsExtrogeneous agents that interfere with the production, release, transport, metabolism, binding, action or elimination of natural hormones in the body responsible for the maintenance of homeostasis and regulation of developmental processesPossible FactorsChemical /Industrial waste, Natural reasons/factorsPreservatives, processed food, unbalanced metabolism Pesticides, etc.Detection of Vg is important to understand the estrogenic contamination of aquatic environment.Representative of a kind of pollution in water/aquatic species