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NANOicon 2022_Prasenjit_2O 002.pptx

  1. Covalently Grafted Ionic Liquid−Graphene Based Electrochemical and Photoelectrochemical Biosensors Dr. Prasenjit Bhunia Assistant Professor Department of Chemistry Silda Chandra Sekhar College Jhargram, West Bengal 721515, India 1
  2. Introduction 2 Graphene/RGO  Two-dimensional π-conjugated structure  Excellent electron acceptors and transporters  Also, able to accelerate electron transfer and effectively suppress charge recombination Ionic Liquid A metal- or metal oxide-free efficient photoelectrocatalyst and electrocatalyst with ionic liquid (1-(3-aminopropyl)-3- methylimidazolium bromide (IL−NH2): Decom. Temp. >300 °C) Why Ionic Liquid?  Impart excellent conductivity to the RGO nanosheets  Reduce the electronic band gap of RGO  Act as a stabilizer for providing stable dispersion (essential for device fabrication)  Act as a binder (for obtaining a stable film on the ITO substrate) β-nicotinamide adenine dinucleotide (NADH)  NADH and its oxidized form (NAD+) (i.e., NADH/NAD+ couple) comprise the cofactor system for more than 300 dehydrogenase enzymes  The NADH/NAD+ couple indeed plays a vital role in biological electron transport  Selected as model biomolecule in this study to demonstrate the proof of concept Electrochemical Sensors: That measures the concentration of certain target molecule by oxidizing or reducing the target molecule at an electrode through measuring the resulting current. Photoelectrochemical detection: Coupling of photoirradiation with electrochemical detection and then measuring the resulting current.
  3. Imidazolium ionic liquid grafted through (a) amide linkage and (b)epoxy ring opening 3 IL-RGO
  4. (a) (b) (c) Characterization of IL-RGO 4  X-ray photoelectron spectroscopy (XPS)  Fourier transform infrared (FTIR) spectroscopy  Raman spectra (excitation wavelength of 514 nm)  Thermogravimetric analyzer  X-ray diffraction (XRD) analysis  Transmission electron microscopy (TEM)  Atomic force microscopy (AFM)  Electrochemical analyzer (CH Instruments, CHI842B) Auxiliary electrode: Platinum wire Reference electrode: Ag/AgCl Working electrode: ITO (Modified) Supporting electrolyte: 0.1 M phosphate buffer solution (PBS) (pH 7.2)  Light source: 300 W xenon lamp, equipped with a monochromator (Newport, Oriel Instruments).
  5. hν Photoelectrochemical Sensing of NADH with IL-RGO 5 250 – 350 nm including visible light Applied potential 0.2 V  Highest photocurrent obtained in 300 nm irradiation
  6. Linear sweep voltammograms of IL-RGO-modified electrode In 0.1M PBS (pH 7.2), Sweep rate: 10 mV s-1 6
  7. hν 7 Proposed Mechanism
  8. 8 Electrochemical Sensing of NADH IL-RGO + Redox Mediator (Azure A) In presence of 0 & 200 μM NADH In presence of 0 & 200 μM NADH RGO +0. 23 V +0. 11 V +0. 05 V -0. 24 V -0. 19 V
  9. 9 NADH detection with IL-RGO-AzA IL-RGO-AzA RGO-AzA Amperometric Response Applied potential: -0.05 V Successive addition: 20 μM NADH (a) RGO (b) RGO-AzA (c) IL-RGO (d) IL-RO-AzA (a) RGO (b) RGO-AzA (c) IL-RGO (d) IL-RO-AzA
  10. Electrochemical Sensing of NADH with N-doped IL-RGO (N-IL-RGO) 10 N-IL-RGO N-IL-RGO IL-RGO IL-RGO
  11. N Ribo ADP H H NH2 O N Ribo ADP NH2 O + H+ + 2e- NADH NAD+ H Electrochemical Oxidation 11 NADH detection with N-IL-RGO Amperometric Response Applied potential: N-RGO-IL (-0.05 V), IL-RGO (0.0 V) & RGO-control (0.25 V) Successive addition: 5 μM NADH N-IL-RGO IL-RGO RGO-Control R2 = 0.98 R2 = 0.99 R2 = 0.97
  12. 12 Summary References 1. Bhunia and Dutta, ACS Appl. Electron. Mater. 3, 2021, 4009−4017. 2. Bhunia and Dutta, Ind. Eng. Chem. Res. 60, 2021, 8035–8042. 3. Bhunia and Dutta, Electrochem. Sci. Adv. 2021, e2100050.  Ionic liquid has been covalently grafted with RGO nanosheets in a single step  The hybrid material has been successfully applied as a photoelectrocatalyst towards NADH detection  The hybrid material, after some modification has also been used as an efficient electrocatalysts towards NADH sensing