Immobilization strategy for enhancing sensitivity of immunosensors:  L -Asparagine–AuNPs as a promising alternative of EDC–NHS activated citrate–AuNPs for antibody immobilization

Raghav, Ragini; Srivastava, Sudha

doi:10.1016/j.bios.2015.11.066

Cited by 71 publications

(34 citation statements)

References 33 publications

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“…It is well known that there is a strong covalent bond interaction between thiol and gold according to the theory of hard and soft (Lewis) acids and bases [45,46]. As for the amino group, it can react with phosphonic group to generate phsophonamidate in the presence of coupling agents [such as dicyclohexylcarbodiimide, N, N-diisopropylcarbodiimide, 1-ethyl-3-(3-(dimethylamino) propyl) carbodimide] [47]. Therefore, the thiol groups in 2-aminoethanethiol molecules would tend to be bound with gold substrate to form AudS covalent bonds, and the amino groups would selectively capture phosphonic groups in MPA molecules in the solution, as schematically shown in Figure 9.…”

Section: Surface Modification Of Sers Substratementioning

confidence: 99%

“…After the coupling agent EDC was added to the ethanol solution of MPA, the coupling between them would activate the phosphonic groups in MPA [see Figure 14(a)] [47]. When the surface-modified SERS substrate was subsequently immersed into the MPA solution, because of the strong interaction between the amino groups in 2-aminoethanethiol and the phosphonic groups in the activated MPA molecules [47], the activated MPA molecules would diffuse onto and be adsorbed on the substrate's surface, as illustrated in Figure 14(b).…”

Section: Amidation Reaction-induced Raman Spectramentioning

confidence: 99%

“…At this time, the adsorbed MPA molecules could react with the 2-aminoethanethiol molecules on the Au-coated Si cone array due to the amino groups in the 2-aminoethanethiol [47], or the amidation reaction between them Evidently, the higher MPA content in the solution would induce the more activated MPA molecules adsorbed on the modified Au-coated Si nanocone array, and the more reaction products C 3 H 10 O 2 NPS bound on the array. This would result in higher Raman peak intensity, showing increase of the Raman peak intensity with the rising MPA content in the solutions, as illustrated in Figure 13(a).…”

Section: Amidation Reaction-induced Raman Spectramentioning

confidence: 99%

See 2 more Smart Citations

SERS-Based Sensitive Detection of Organophosphorus Nerve Agents

Zhao¹,

Liu²,

Cai³

2018

Raman Spectroscopy

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Organophosphorus nerve agents, such as sarin, tabun, cyclosarin and soman, belong to the most toxic substances. So, it is very important to quickly detect it in trace-level and on-site or portable way. But, both fast and trace detections have been expected because current techniques are of low sensitivity or of poor selectivity and are time-consuming. The surface-enhanced Raman scattering (SERS)-based detection could be a suitable and effective method. However, the organophosphorus nerve agents only very weakly interact with highly SERS-activated noble metal substrates and are hardly adsorbed on them. In this case, it is difficult to detect such molecules, with reproducible or quantitative measurements and trace level, by the normal SERS technique. Recently, there have been some works on the SERS-based detection of the organophosphorus molecules. In this chapter, we introduce the main progresses in this field, including (1) the thin water film confinement and evaporation concentrating strategy and (2) the surface modification and amidation reaction. These works provide new ways for highly efficient SERS-based detection of the organophosphorus nerve agents and some other target molecules that weakly interact with the coin metal substrates.

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Section: Surface Modification Of Sers Substratementioning

confidence: 99%

Section: Amidation Reaction-induced Raman Spectramentioning

confidence: 99%

Section: Amidation Reaction-induced Raman Spectramentioning

confidence: 99%

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SERS-Based Sensitive Detection of Organophosphorus Nerve Agents

Zhao¹,

Liu²,

Cai³

2018

Raman Spectroscopy

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“…And glutaraldehyde along with 1-ethyl-3-(3-dimethyl aminopropyl)carbodiimide/N-hydroxysuccinimide (EDC/NHS) is the most prominent cross-linking agents used. 12,13 The use of cross linkers in immunosensor fabrications increases the step in the biosensor preparation and creates the possibility of introducing bonds that may hinder the bio-recognition process and thus a deviation from biomimicry. 14 It is therefore necessary to utilise materials that are biocompatible (that will not hinder the biological integrity of the biomolecules) and which can increase the electrode surface area and enhance conductivity.…”

Section: Introductionmentioning

confidence: 99%

Towards cancer diagnostics – an α-feto protein electrochemical immunosensor on a manganese(iv) oxide/gold nanocomposite immobilisation layer

2018

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“…78 To circumvent the concerns and challenges of direct adsorption, numerous approaches have been explored to immobilize protein onto gold nanoparticles through covalent coupling chemistry. [79][80][81][82][83][84] Carbohydrates if present on the protein can be used for attachment; however, along with being time intensive this method requires carbohydrates to be present on the protein and is labor intensive. 19 Covalent modification of gold nanoparticles using bifunctional crosslinking chemistry molecules such as DTSSP (3,3'-dithiobis(sulfosuccinimidyl propionate)) is one of the most widely used method of attachment.…”

Section: Introductionmentioning

confidence: 99%

Formation, Characterization, And Optimization Of Antibody-Gold Nanoparticle Conjugates

Filbrun¹

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Protein modified gold nanoparticle based immunoassays are the basis of many novel detection techniques. There are many groups working on novel immunoassays but there is still much to understand about how many proteins are attached onto each nanoparticle and much to improve on immobilization methods. This thesis work is devoted to improving techniques for the quantification of protein immobilized on the gold nanoparticle and development of a novel approach to immobilize protein independent of pH.The ability to evaluate antibody immobilization onto gold nanoparticles is critical for assessing coupling chemistry and optimizing the sensitivity of nanoparticle-enabled biosensors.Herein, we developed a fluorescence-based method for directly quantifying antibodies bound onto gold nanoparticles. Antibody-modified gold nanoparticles were treated with KI/I2 etchant to dissolve the gold nanoparticles. A desalting spin column was used to recover the antibody released from the nanoparticles, and NanoOrange, a fluorescent dye, was used to quantify the antibody. We determined 309 ± 93 antibodies adsorb onto each 60 nm gold nanoparticle (2.6 × 10 10 NP/mL), which is consistent with a fully adsorbed monolayer based on the footprint of an IgG molecule. Moreover, the increase in hydrodynamic diameter of the conjugated nanoparticle (76 nm) compared to that of the unconjugated nanoparticle (62 nm) confirmed that multilayers did not form. A more conventional method of indirectly quantifying the adsorbed antibody by analysis of the supernatant overestimated the antibody surface coverage (660 ± 87 antibodies per nanoparticle); thus, we propose the method described herein as a more accurate alternative to the conventional approach.The immobilization of antibody onto gold nanoparticles is important for many novel nanoparticle based immunoassays. Current methods of immobilization are limited by the inability to immobilize antibody onto gold nanoparticles over a range of pH values. Direct adsorption requires the pH to be slightly higher than the isoelectric point of the antibody and covalent attachment via bifunctional crosslinking chemistry molecules requires a specific pH as well. This is an issue when working with multiple antibodies at once for multiplex detection. In this thesis, we present a new method of immobilization by which the antibody is modified via a molecule with a N-hydroxysuccinimidyl ester group, then adsorbed onto a gold nanoparticle. We demonstrate that modification of antibodies allows for adsorption onto gold nanoparticles independent of pH. Furthermore, we show that this modification method is applicable to multiple antibodies. Finally, we show that these modified antibodies are active and comparable to conventional assays.

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Immobilization strategy for enhancing sensitivity of immunosensors: L -Asparagine–AuNPs as a promising alternative of EDC–NHS activated citrate–AuNPs for antibody immobilization

Cited by 71 publications

References 33 publications

SERS-Based Sensitive Detection of Organophosphorus Nerve Agents

SERS-Based Sensitive Detection of Organophosphorus Nerve Agents

Towards cancer diagnostics – an α-feto protein electrochemical immunosensor on a manganese(iv) oxide/gold nanocomposite immobilisation layer

Formation, Characterization, And Optimization Of Antibody-Gold Nanoparticle Conjugates

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