Adsorption and sub-nanomolar sensing of thioflavin T on colloidal gold nanoparticles, silver nanoparticles and silver-coated films studied using surface-enhanced Raman scattering

Maiti, Namita; Chadha, Ridhima; Das, Sudip Kumar; Kapoor, Sudhir

doi:10.1016/j.saa.2015.05.043

Cited by 24 publications

(19 citation statements)

References 33 publications

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“…The di-anionic tautomer of DMTD is the dithiolate and its optimized structure (B3LYP/aug-cc-pvdz) is shown in Figure 3(F). The computed energies suggest that the thione-thiolate form is more stable than the thiol-thiolate tautomer by 14 The acid dissociation constants of DMTD are known to be 1.4 and 7.4 68 (2.1 and 7.5) 69 , making its neutral form (dithiol, thione-thiol and dithione) a very strong acid and its monoanionic form (thione-thiolate and thiol-thiolate) a weak acid. Hence, at an acidic pH 1.5, DMTD exists mainly in the neutral form as dithiol, thione-thiol or dithone whereas, at pH ≥ 8 it remains primarily as dithiolate.…”

Section: Computational Resultsmentioning

confidence: 99%

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Surface selective binding of 2,5-dimercapto-1,3,4-thiadiazole (DMTD) on silver and gold nanoparticles: a Raman and DFT study

et al. 2016

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The optimized structures of all possible Ag and Au complexes of DMTD and the Raman spectra of solid DMTD and its solution at pH 1.5 from 2000-3800 cm -1 region are included in the Supporting Information. SeeThe binding affinity of 2,5-Dimercapto-1,3,4-thiadiazole (DMTD) on noble metal silver (Ag) and gold (Au) nanoparticles (NPs) was investigated using the surface-enhanced Raman scattering (SERS) technique in combination with density functional theoretical (DFT) calculations. DMTD contains different anchoring groups; firstly the thiadiazole ring nitrogen atoms, secondly the ring sulphur atom, thirdly the thiocarbonyl sulfur atoms and fourthly the ring п electrons. SERS combined with DFT calculations provided useful insight into the interaction between the molecule and metal, thus, illustrating the active sites of DMTD and the metal substrates being directly involved in binding. Raman, SERS and DFT studies were further exploited to study the tautomeric conformations of DMTD present in solid, aqueous solution and on the Ag and Au NP surfaces. The Raman spectrum indicated the existence of mainly the dithiol tautomer in the solid state with little contribution from the dithione and the thione-thiol forms. The pH-dependent Raman study of DMTD in aqueous solution clearly demonstrated the existence of different tautomers of DMTD with the changes in acidity or basicity. The SERS study of DMTD on the Ag NP surface with support from DFT calculations clearly suggested the abundance of mainly the thiol-thiolate tautomer at neutral pH while the dithiol form was predominant at acidic pH. The concentrationdependent SERS study on the Ag NP surface at acidic pH, indicated the preferential existence of the dithione form at low concentrations while the dithiol form is predominant at higher concentrations. On the Au NP surface at acidic pH, the abundance of the dithiol tautomer with slight contributions from the thione-thiol and the dithione forms are indicated. The binding is mainly through the thiadiazole ring N atom in case of Ag NPs whereas it is from the thiocarbonyl or the thiadiazole ring S atom in case of Au NPs. This selective binding observed in case of DMTD may be further extended in designing novel plasmonic nanostructures.

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Section: Computational Resultsmentioning

confidence: 99%

“…the binding sites and the orientation of the adsorbates on the metal surfaces. [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] SERS has also been exploited recently for studying surface-catalyzed oxidation 23,24 and charge rearrangement reactions 25 . Noble-metal NPs are ideal candidates for studying such interactions.…”

Section: Introductionmentioning

confidence: 99%

Surface selective binding of 2,5-dimercapto-1,3,4-thiadiazole (DMTD) on silver and gold nanoparticles: a Raman and DFT study

et al. 2016

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“…When necessary, Au‐coated samples were characterized via scanning electron microscopy (SEM) using an environmental SEM system (Quanta 200, FEI, Hillsboro, OR, USA). After metal evaporation, samples were immersed in different concentrations of aqueous ThT solution at 28 °C for 12 hr, washed with DI water, and dried at room temperature . SERS spectra of fabricated films were then collected by a Raman module with a cooled charge‐coupled device detector (DeltaNu Examiner Laramie, WY, USA).…”

Section: Experimental Partmentioning

confidence: 99%

“…Thioflavin‐T (ThT) is a widely used fluorescent molecule to diagnose the presence of senile plaques in AD, where a significant fluorescence enhancement of the dye occurs upon incorporating into the beta sheet‐rich structures of the amyloid fibrils . Moreover, the molecule can covalently attach to metal surfaces that allow the formation of intensified characteristic ThT SERS signals …”

Section: Introductionmentioning

confidence: 99%

Fabrication of thioflavin‐T‐modified nanopillared SERS substrates for ultrasensitive beta‐amyloid peptide detection

Altuntaş

Büyükserin

2018

J Raman Spectroscopy

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Alzheimer disease (AD) is a major cause of death in the world, and despite intense efforts, there is still no cure for this neurodegenerative disorder. Therefore, early diagnosis of AD is of prime importance, and extensive studies are being conducted to improve the current early detection capabilities and to identify new potential biomarkers for this disease. Here in, we report the fabrication of a novel nanobiosensor platform for the surface‐enhanced Raman spectroscopy (SERS)‐based ultrasentisitive detection of beta‐amyloid (1–42) peptide (Aβ[1–42]), a well‐established biomarker of AD. Polymeric films having multibranched nanopillared surfaces (MNS) were first fabricated by drop‐casting polycarbonate solutions onto anodized aluminum oxide molds that possess hierarchically branched pores. After peeling from the nanoporous molds, a 20‐nm Au coating allowed these MNS substrates to sense sub‐picomolar levels of Thioflavin‐T (ThT), a SERS‐active dye, clinically used to diagnose amyloid plaque presence. Of particular interest, the ThT‐modified MNS films demonstrated a gradual ThT SERS signal suppression when incubated with increasing concentrations of Aβ(1–42), and this trend was used to obtain a limit of detection value of 0.5 pg/ml and a linear dynamic range between 0.5 pg/ml and 100 ng/ml. The developed biosensor platform has stable ThT SERS signals for extended periods and displayed promising results in artificial saliva. Ongoing studies are focused on its potential with real body fluids.

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“…In SERS, the enhancement of Raman intensity occurs mainly due to the electromagnetic and the chemical effect . Recently, SERS spectroscopy has been widely used as a promising tool for the detection/sensing of various organic and biological molecules with higher sensitivity and precision . This technique has also been exploited to study surface‐induced catalytic reactions .…”

Section: Introductionmentioning

confidence: 99%

Distinguishing genomicDNAofBrassica junceaandArabidopsis thalianausing surface‐enhanced Raman scattering

Mirajkar

Dhayagude

Maiti

et al. 2019

J Raman Spectroscopy

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The emergence of the surface-enhanced Raman scattering (SERS) technique as a prospective approach for the label-free detection and fingerprinting of deoxyribonucleic acid (DNA) of microorganisms motivated us to detect traces of genomic DNA (gDNA) of Brassicaceae plant species, namely, Brassica juncea and Arabidopsis thaliana. DNA from the young leaf tissue of germinated B. juncea was extracted by modified cetyl trimethyl ammonium bromide extraction method and added to silver (Ag) and gold (Au) nanoparticles (NPs). The reduction in the absorbance of the surface plasmon resonance band of the metal NPs along with the appearance of a red-shifted band indicated that DNA gets adsorbed on the metal NPs. The change in helicity of gDNA upon interaction with metal NPs was confirmed from circular dichroism studies. Dynamic light scattering measurements indicated that extent of aggregation is more in gDNA functionalized Au NPs than in Ag NPs. The transmission electron microscopy results corroborated the dynamic light scattering data. The marginal change in zeta potential value of Ag and Au NPs after binding to gDNA indicated good stability of the functionalized metal NPs. The SERS spectra revealed that adenine and deoxyribose were the active sites of gDNA that interacted with the metal NPs. From SERS, the limit of detection of gDNA was found to be~10 and 1 ng μl −1 with Ag and Au NPs. The wavelength-dependent Raman study showed that the charge transfer effect contributed to the SERS enhancement in addition to the electromagnetic effect. The SERS spectra of gDNA of A. thaliana functionalized Ag NPs were found to be different as compared with the gDNA of B. juncea probably due to the difference in their genome length and biochemical variability. Moreover, the Raman spectral signatures might differ due to changes in the adsorption pattern of the nucleotide bases on metal NPs surfaces.Shriram Mirajkar and Akshay Dhayagud have contributed equally to the work.

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Adsorption and sub-nanomolar sensing of thioflavin T on colloidal gold nanoparticles, silver nanoparticles and silver-coated films studied using surface-enhanced Raman scattering

Cited by 24 publications

References 33 publications

Surface selective binding of 2,5-dimercapto-1,3,4-thiadiazole (DMTD) on silver and gold nanoparticles: a Raman and DFT study

Surface selective binding of 2,5-dimercapto-1,3,4-thiadiazole (DMTD) on silver and gold nanoparticles: a Raman and DFT study

Fabrication of thioflavin‐T‐modified nanopillared SERS substrates for ultrasensitive beta‐amyloid peptide detection

Distinguishing genomicDNAofBrassica junceaandArabidopsis thalianausing surface‐enhanced Raman scattering

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