Determination of aqueous antibiotic solutions using SERS nanogratings

Hong, Koh Yiin; Albuquerque, Carlos Diego Lima de; Poppi, Ronei J.; Brolo, Alexandre G.

doi:10.1016/j.aca.2017.05.025

Cited by 70 publications

(40 citation statements)

References 63 publications

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“…This confirms that the number of molecules adsorbed in the electromagnetic hot spots of the SCs is solely dependent on the bulk concentration and not on the pH of the medium, reaffirming the effectiveness of the SCs as a universal analytical platform. SERS as an analytical tool has traditionally relied on trapping of analyte molecules on the SERS platform through either electrostatic forces or host–guest interaction or combination of these . Both these routes of immobilizing the analyte molecules on the SERS platform critically depend on the ionic form of analyte and are thus not universal.…”

Section: Resultsmentioning

confidence: 99%

Surface‐enhanced Raman scattering platform operating over wide pH range with minimal chemical enhancement effects: Test case of tyrosine

Moronshing

Bhaskar

Mondal

et al. 2019

J Raman Spectroscopy

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Decoupling the contributions of electromagnetic and chemical enhancements in surface-enhanced Raman scattering (SERS) would lead to greater reliability and applicability in biological systems that involve large, localized pH gradients. However, suppressing short-range, chemical enhancement effects in SERS has proved challenging due to unavoidable charge-transfer interactions between analyte and the SERS platforms. This extends to both lithographically fabricated top-down and self-assembled bottom-up SERS platforms. Here, we employ a Soret effect-driven monodisperse nanoparticle assembly (Soret colloids [SCs]) with negligible surface charge (ξ < 16 mV) that provides exceptional SERS enhancement (analytical enhancement factor~10 6 ) contributed predominantly by excitation of localized surface plasmon resonance (electromagnetic enhancement) with minimal electrostatic or charge-transfer-based short-range interactions. Significantly, the low ξ of SCs is invariant over a wide pH range (pH 4-7) indicating minimal electrostatic surface charge. The interaction of such SCs with ionic analytes such as tyrosine leads to uniform SERS dictated by electromagnetic enhancement mechanism. The absence of contribution from chemical enhancement is clearly established by the vibrational fingerprints of tyrosine that are devoid of any spectral shifts originating from charge transfer between tyrosine and SCs. Accordingly, all features of the tyrosine that are independent of pH such as C-H stretch (2,700-3,000 cm −1 ) and C-C stretch (1,440 cm −1 ) and C-C-C bending (1,010 cm −1 ) are completely preserved without any spectral shifts. Simultaneously, pH-dependent vibrational features of tyrosine such as N-H stretch (1,545 cm −1 ), C¼O stretch (1,700 cm −1 ), COO − stretch (1,640 cm −1 ), C-O stretch (1,240 cm −1 ), and amide III bands (1,246 and 1,260 cm −1 ) are clearly observed. The intensities of such bands correspond exactly to the ionic state of tyrosine as dictated by the pH of the medium. This is reinforced by the crossover in the intensity of the pH-dependent vibrational modes (C-O vs. COOstretch, COO − vs. NH 3 + stretch) that coincides with the isoelectric pH of tyrosine. Finally, reliable quantification of the charge and concentration of tyrosine using SCs

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Section: Resultsmentioning

confidence: 99%

Surface‐enhanced Raman scattering platform operating over wide pH range with minimal chemical enhancement effects: Test case of tyrosine

Moronshing

Bhaskar

Mondal

et al. 2019

J Raman Spectroscopy

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“… 1 − 3 In particular, nanoplasmonic sensors are attractive chip-based platforms that provide strongly confined surface plasmon excitations at the sensor interface to interact with thin layers of bioanalytes for highly sensitive detection at molecular dimensions. 4 − 7 Besides their extensive applications at visible and near-infrared frequencies, engineered nanoplasmonic structures deliver unique possibilities for biomolecular studies with ultrasensitive surface-enhanced infrared absorption spectroscopy based on the distinct molecular vibrations in the mid-infrared (mid-IR) range. 8 − 12 The mid-IR vibrational signatures of molecules correspond to chemical bonds among their constituent elements and therefore enable nondestructive and label-free characterization.…”

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confidence: 99%

Real-Time In Situ Secondary Structure Analysis of Protein Monolayer with Mid-Infrared Plasmonic Nanoantennas

et al. 2018

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Dynamic detection of protein conformational changes at physiological conditions on a minute amount of samples is immensely important for understanding the structural determinants of protein function in health and disease and to develop assays and diagnostics for protein misfolding and protein aggregation diseases. Herein, we experimentally demonstrate the capabilities of a mid-infrared plasmonic biosensor for real-time and in situ protein secondary structure analysis in aqueous environment at nanoscale. We present label-free ultrasensitive dynamic monitoring of β-sheet to disordered conformational transitions in a monolayer of the disease-related α-synuclein protein under varying stimulus conditions. Our experiments show that the extracted secondary structure signals from plasmonically enhanced amide I signatures in the protein monolayer can be reliably and reproducibly acquired with second derivative analysis for dynamic monitoring. Furthermore, by using a polymer layer we show that our nanoplasmonic approach of extracting the frequency components of vibrational signatures matches with the results attained from gold-standard infrared transmission measurements. By facilitating conformational analysis on small quantities of immobilized proteins in response to external stimuli such as drugs, our plasmonic biosensor could be used to introduce platforms for screening small molecule modulators of protein misfolding and aggregation.

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“…In chemical sensors , receptors are synthetic molecules having in their structure functional groups able to selectively interact with an analyte. They are used in sensors for the determination of both individual chemical compounds and groups of substances, which are implemented in chemometric systems, such as an “electronic nose” or an “electronic tongue” [ 35 , 36 ].…”

Section: Sensors Characteristicsmentioning

confidence: 99%

Sensors Based on Bio and Biomimetic Receptors in Medical Diagnostic, Environment, and Food Analysis

et al. 2018

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Analytical chemistry is now developing mainly in two areas: automation and the creation of complexes that allow, on the one hand, for simultaneously analyzing a large number of samples without the participation of an operator, and on the other, the development of portable miniature devices for personalized medicine and the monitoring of a human habitat. The sensor devices, the great majority of which are biosensors and chemical sensors, perform the role of the latter. That last line is considered in the proposed review. Attention is paid to transducers, receptors, techniques of immobilization of the receptor layer on the transducer surface, processes of signal generation and detection, and methods for increasing sensitivity and accuracy. The features of sensors based on synthetic receptors and additional components (aptamers, molecular imprinted polymers, biomimetics) are discussed. Examples of bio- and chemical sensors’ application are given. Miniaturization paths, new power supply means, and wearable and printed sensors are described. Progress in this area opens a revolutionary era in the development of methods of on-site and in-situ monitoring, that is, paving the way from the “test-tube to the smartphone”.

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Determination of aqueous antibiotic solutions using SERS nanogratings

Cited by 70 publications

References 63 publications

Surface‐enhanced Raman scattering platform operating over wide pH range with minimal chemical enhancement effects: Test case of tyrosine

Surface‐enhanced Raman scattering platform operating over wide pH range with minimal chemical enhancement effects: Test case of tyrosine

Real-Time In Situ Secondary Structure Analysis of Protein Monolayer with Mid-Infrared Plasmonic Nanoantennas

Sensors Based on Bio and Biomimetic Receptors in Medical Diagnostic, Environment, and Food Analysis

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