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Karolína M. Šišková , Dept. of Biophysics, CRH Faculty of Science

Interaction of nanoparticles with amino acids and a physiologically important model protein studied by spectroscopic techniques. Karolína M. Šišková , Dept. of Biophysics, CRH Faculty of Science Palacký University in Olomouc Czech Republic.

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Karolína M. Šišková , Dept. of Biophysics, CRH Faculty of Science

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  1. Interaction of nanoparticles with amino acids and a physiologically important model protein studied by spectroscopic techniques Karolína M. Šišková, Dept. of Biophysics, CRH Faculty of Science Palacký University in Olomouc Czech Republic Advanced Materials & Processing, September 07-08, 2017, Edinburgh Scotland

  2. Graphical abstract of this talk Ag NP T P W UV-Vis and SERS spectroscopies R K F C D M S H E Y Au NP Advanced Materials & Processing, September 07-08, 2017, Edinburgh Scotland

  3. Ag and Au NPs Unique optical properties Ag NPs = Antimicrobial agents Scholl J.A. et al. Quantum plasmon resonances of individual metallic nanoparticles. Nature, 2012, 483, 421-427 • Commercially exploited • their toxicity and ecotoxicity need to be carefully evaluated Kahraman M. et al. Fundamentals and applications of SERS-based bioanalytical sensing. Nanophotonics, 2017, 6 (5), 831-852 Rai M. et al. Silver nanoparticles: The powerful nanoweapon against multidrug-resistant bacteria. J. Appl. Microbiol. 2012, 112, 841−852 Siskova K.M. et al. Revisiting spontaneous silver nanoparticles formation: a factor influencing the determination of minimum inhibitory concentration values? AIMS Environ. Sci. 2015, 2 (3), 607-622 Their main features: Localized surface plasmon - dependent on composition, size, shape, aggregation state Electric double-layer - changed by surface functionalization

  4. 9.5 + 2.9 nm 9.8 + 2.7 nm Ag and Au NPs in deionized water UV-Vis spectra: surface plasmon extinction Here example of isolated spherical NPs prepared by borohydride reduction TEM images: size and shape of NPs

  5. Ag NPs Electric bilayer (EB) enveloping each NP in aqueous solution; negative zeta potential values of NPs If EB destroyed (e.g. adsorption of AA molecules), aggregation proceeds – observable by naked eye:

  6. Interaction of Ag nanoparticles with amino acids based on UV-Vis absorption measurements 9 from 13 AAs interact with Ag NPs! Functional groups of AAs play a key role; AA concentration is also important. Notes: final concentrations of AA are mentioned; + means aggregation observed, - no aggregation

  7. Au NPs Aggregation observable by naked eye > Recorded by UV-Vis extinction

  8. Interaction of Au nanoparticles with amino acids based on UV-Vis absorption measurements 2 from 13 AAs interact with Au NPs! Functional groups of AAs play a key role; AA concentration is also important. Notes: final concentrations of AA are mentioned; + means aggregation observed, - no aggregation

  9. l hn - light Surface-Enhanced Raman Scattering - principle Not in real scale = only scheme: Adsorbate molecule Ag NP and/or Au NP Oscillating dipole Enhancement (G) of initial and Raman scattered light G ~ E2laser* E2Raman~ E4

  10. Example of phenylalanine (at pH 7): Raman scattering vs. SERS (using Agbh NPs) Region of Ag-O, Ag-S, Ag-N vibrations 0 Fingerprint region Raman shift (cm-1)

  11. Interaction of AgbhNPs with AAs (1mM) based on SERS C interacted with AgNPs after pH increase due to HS/-S transition Positively charged AAs (K, R) = more attractive for negatively chargedAgNPs Neutral AAs with AgNPs = good SERS signals (except C) Negatively charged AAs (E, D, P) - the time of interaction matters.

  12. Interaction of AgCitrNPs with AAs (1mM) based on SERS Citrates take more space than borates + bound through carboxylic groups => NPs less reactive Positively charged AAs = more attractive for negatively chargedAgNPs (citrates on surface) Neutral AAs with AgCitr = no SERS signals Notes: yes/no indicates if SERS signal observed or not Length of AA carbon chain matters: D vs. E

  13. Conclusions Outlook Evidenced that AuNPsare less reactive than AgNPs. Species on the surface of NPs play a crutial role (citrates vs. borates). Zeta potential valueof NPs vs. charge of amino acids in solutionoftheparticular pH is animportantfactor. Ionic vs. covalent interaction between amino acids and NPs canbedistinguished in SERS. • SERS signal from different AuNPs at 633 nm excitation • Influence of pH changes on SERS spectra of AuNPs • SERS signal + Raman optical activity measurements from a physiologically important model protein, Na+/K+-ATPase • Fluorescence spectra of NPs + amino acids (namely Y, F, W)

  14. Acknowledgement • Dr. Eva Kocisova and Assoc. Prof. Peter Mojzes Dept. of Physics of Biomolecules, Institute of Mathematics and Physics, Charles University, Prague, Czech Republic • Assoc. Prof. Martin Kubala, Dept. of Biophysics, CRH, • Dr. Josef Kapitan, Dept. of Optics, Faculty of Science, Palacky University in Olomouc, Czech Republic Thank you for your attention!

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