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Dhillon AK, Sharma A, Yadav V, Singh R, Ahuja T, Barman S, Siddhanta S. Raman spectroscopy and its plasmon-enhanced counterparts: A toolbox to probe protein dynamics and aggregation. WILEY INTERDISCIPLINARY REVIEWS. NANOMEDICINE AND NANOBIOTECHNOLOGY 2024; 16:e1917. [PMID: 37518952 DOI: 10.1002/wnan.1917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 06/22/2023] [Accepted: 07/06/2023] [Indexed: 08/01/2023]
Abstract
Protein unfolding and aggregation are often correlated with numerous diseases such as Alzheimer's, Parkinson's, Huntington's, and other debilitating neurological disorders. Such adverse events consist of a plethora of competing mechanisms, particularly interactions that control the stability and cooperativity of the process. However, it remains challenging to probe the molecular mechanism of protein dynamics such as aggregation, and monitor them in real-time under physiological conditions. Recently, Raman spectroscopy and its plasmon-enhanced counterparts, such as surface-enhanced Raman spectroscopy (SERS) and tip-enhanced Raman spectroscopy (TERS), have emerged as sensitive analytical tools that have the potential to perform molecular studies of functional groups and are showing significant promise in probing events related to protein aggregation. We summarize the fundamental working principles of Raman, SERS, and TERS as nondestructive, easy-to-perform, and fast tools for probing protein dynamics and aggregation. Finally, we highlight the utility of these techniques for the analysis of vibrational spectra of aggregation of proteins from various sources such as tissues, pathogens, food, biopharmaceuticals, and lastly, biological fouling to retrieve precise chemical information, which can be potentially translated to practical applications and point-of-care (PoC) devices. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Diagnostic Tools > Diagnostic Nanodevices Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.
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Affiliation(s)
| | - Arti Sharma
- Department of Chemistry, Indian Institute of Technology Delhi, New Delhi, India
| | - Vikas Yadav
- Department of Chemistry, Indian Institute of Technology Delhi, New Delhi, India
| | - Ruchi Singh
- Department of Chemistry, Indian Institute of Technology Delhi, New Delhi, India
| | - Tripti Ahuja
- Department of Chemistry, Indian Institute of Technology Delhi, New Delhi, India
| | - Sanmitra Barman
- Center for Advanced Materials and Devices (CAMD), BML Munjal University, Haryana, India
| | - Soumik Siddhanta
- Department of Chemistry, Indian Institute of Technology Delhi, New Delhi, India
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2
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Sondhi P, Neupane D, Bhattarai JK, Demchenko AV, Stine KJ. Facile fabrication of hierarchically nanostructured gold electrode for bio-electrochemical applications. J Electroanal Chem (Lausanne) 2022; 924:116865. [PMID: 36405880 PMCID: PMC9673609 DOI: 10.1016/j.jelechem.2022.116865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Nanoporous gold (NPG) is one of the most extensively investigated nanomaterials owing to its tunable pore size, ease of surface modification, and range of applications from catalysis, actuation, and molecular release to the development of electrochemical sensors. In an effort to improve the usefulness of NPG, a simple and robust method for the fabrication of hierarchical and bimodal nanoporous gold electrodes (hb-NPG) containing both macro-and mesopores is reported using electrochemical alloying and dealloying processes to engineer a bicontinuous solid/void morphology. Scanning electron microscopy (color SEM) images depict the hierarchical pore structure created after the multistep synthesis with an ensemble of tiny pores below 100 nm in size located in ligaments spanning larger pores of several hundred nanometers. Smaller-sized pores are exploited for surface modification, and the network of larger pores aids in molecular transport. Cyclic voltammetry (CV) was used to compare the electrochemically active surface area of the hierarchical bimodal structure with that of the regular unimodal NPG with an emphasis on the critical role of both dealloying and annealing in creating the desired structure. The adsorption of different proteins was followed using UV-vis absorbance measurements of solution depletion revealing the high loading capacity of hb-NPG. The surface coverage of lipoic acid on the hb-NPG was analyzed using thermogravimetric analysis (TGA) and reductive desorption. The roughness factor determinations suggest that the fabricated hb-NPG electrode has tremendous potential for biosensor development by changing the scaling relations between volume and surface area which may lead to improved analytical performance. We have chosen to take advantage of the surface architectures of hb-NPG due to the presence of a large specific surface area for functionalization and rapid transport pathways for faster response. It is shown that the hb-NPG electrode has a higher sensitivity for the amperometric detection of glucose than does an NPG electrode of the same geometric surface area.
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Affiliation(s)
- Palak Sondhi
- Department of Chemistry and Biochemistry, University of Missouri–St. Louis, Saint Louis, MO 63121, USA
| | - Dharmendra Neupane
- Department of Chemistry and Biochemistry, University of Missouri–St. Louis, Saint Louis, MO 63121, USA
| | - Jay K. Bhattarai
- Department of Chemistry and Biochemistry, University of Missouri–St. Louis, Saint Louis, MO 63121, USA
| | | | - Keith J. Stine
- Department of Chemistry and Biochemistry, University of Missouri–St. Louis, Saint Louis, MO 63121, USA
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Mohd Asri MA, Nordin AN, Ramli N. Low-cost and cleanroom-free prototyping of microfluidic and electrochemical biosensors: Techniques in fabrication and bioconjugation. BIOMICROFLUIDICS 2021; 15:061502. [PMID: 34777677 PMCID: PMC8577868 DOI: 10.1063/5.0071176] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 10/22/2021] [Indexed: 05/18/2023]
Abstract
Integrated microfluidic biosensors enable powerful microscale analyses in biology, physics, and chemistry. However, conventional methods for fabrication of biosensors are dependent on cleanroom-based approaches requiring facilities that are expensive and are limited in access. This is especially prohibitive toward researchers in low- and middle-income countries. In this topical review, we introduce a selection of state-of-the-art, low-cost prototyping approaches of microfluidics devices and miniature sensor electronics for the fabrication of sensor devices, with focus on electrochemical biosensors. Approaches explored include xurography, cleanroom-free soft lithography, paper analytical devices, screen-printing, inkjet printing, and direct ink writing. Also reviewed are selected surface modification strategies for bio-conjugates, as well as examples of applications of low-cost microfabrication in biosensors. We also highlight several factors for consideration when selecting microfabrication methods appropriate for a project. Finally, we share our outlook on the impact of these low-cost prototyping strategies on research and development. Our goal for this review is to provide a starting point for researchers seeking to explore microfluidics and biosensors with lower entry barriers and smaller starting investment, especially ones from low resource settings.
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Affiliation(s)
- Mohd Afiq Mohd Asri
- Department of Electrical and Computer Engineering, Kulliyyah of Engineering, International Islamic University Malaysia, 53100 Gombak, Selangor, Malaysia
| | - Anis Nurashikin Nordin
- Department of Electrical and Computer Engineering, Kulliyyah of Engineering, International Islamic University Malaysia, 53100 Gombak, Selangor, Malaysia
- Author to whom correspondence should be addressed:
| | - Nabilah Ramli
- Department of Mechanical Engineering, Kulliyyah of Engineering, International Islamic University Malaysia, 53100 Gombak, Selangor, Malaysia
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4
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The impact of caffeine on tau-tau interaction: LSPR detection, structural modification and molecular dynamics simulation. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.115914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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5
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He Q, Yang J, Zabotina OA, Yu C. Surface-enhanced Raman spectroscopic chemical imaging reveals distribution of pectin and its co-localization with xyloglucan inside onion epidermal cell wall. PLoS One 2021; 16:e0250650. [PMID: 33951055 PMCID: PMC8099099 DOI: 10.1371/journal.pone.0250650] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Accepted: 04/12/2021] [Indexed: 12/01/2022] Open
Abstract
The primary plant cell wall is a complex matrix composed of interconnected polysaccharides including cellulose, hemicellulose, and pectin. Changes of this dynamic polysaccharide system play a critical role during plant cell development and differentiation. A better understanding of cell wall architectures can provide insight into the plant cell development. In this study, a Raman spectroscopic imaging approach was developed to visualize the distribution of plant cell wall polysaccharides. In this approach, Surface-enhanced Raman scattering (SERS through self-assembled silver nanoparticles) was combined with Raman labels (4-Aminothiophenol. 4ATP) and targeted enzymatic hydrolysis to improve the sensitivity, specificity, and throughput of the Raman imaging technique, and to reveal the distribution of pectin and its co-localization with xyloglucan inside onion epidermal cell (OEC) wall. This technique significantly decreased the required spectral acquisition time. The resulted Raman spectra showed a high Raman signal. The resulted Raman images successfully revealed and characterized the pectin distribution and its co-localization pattern with xyloglucan in OEC wall.
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Affiliation(s)
- Qing He
- Department of Agricultural and Biosystems Engineering, Iowa State University, Ames, IA, United States of America
| | - Jingyi Yang
- Department of Agricultural and Biosystems Engineering, Iowa State University, Ames, IA, United States of America
| | - Olga A. Zabotina
- Department of Molecular Biology, Biochemistry and Biophysics, Iowa State University, Ames, IA, United States of America
| | - Chenxu Yu
- Department of Agricultural and Biosystems Engineering, Iowa State University, Ames, IA, United States of America
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Ngadimin KD, Stokes A, Gentile P, Ferreira AM. Biomimetic hydrogels designed for cartilage tissue engineering. Biomater Sci 2021; 9:4246-4259. [DOI: 10.1039/d0bm01852j] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Cartilage-like hydrogels based on materials like gelatin, chondroitin sulfate, hyaluronic acid and polyethylene glycol are reviewed and contrasted, revealing existing limitations and challenges on biomimetic hydrogels for cartilage regeneration.
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Affiliation(s)
- Kresanti D. Ngadimin
- Faculty of Medical Sciences
- Newcastle University
- Newcastle upon Tyne
- UK
- Faculty of Medicine
| | - Alexander Stokes
- Faculty of Science
- Agriculture & Engineering
- Newcastle University
- Newcastle upon Tyne
- UK
| | - Piergiorgio Gentile
- Faculty of Science
- Agriculture & Engineering
- Newcastle University
- Newcastle upon Tyne
- UK
| | - Ana M. Ferreira
- Faculty of Science
- Agriculture & Engineering
- Newcastle University
- Newcastle upon Tyne
- UK
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Abstract
Gravimetric transducers produce a signal based on a change in mass. These transducers can be used to construct gas sensors or biosensors using odorant binding proteins (OBPs) as recognition elements for small volatile organic compounds. The methods described in this chapter are based on the immobilization of the OBPs onto functionalized (activated) self-assembled monolayer (SAMs) on gold and on nanocrystalline diamond surfaces. Depending on the surface immobilization methods used to fabricate the biosensor, recombinant proteins can be engineered to express six histidine tags either on the N-terminal or C-terminal of the proteins and these can also be used to facilitate protein immobilization. These methods are used to produce functional sensors based on quartz crystal microbalances or surface acoustic wave devices and are also applicable to other types of gravimetric transducers.
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Affiliation(s)
- Khasim Cali
- Department of Instrumentation and Analytical Science, The University of Manchester, Manchester, United Kingdom
| | | | - Krishna C Persaud
- Department of Instrumentation and Analytical Science, The University of Manchester, Manchester, United Kingdom.
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Bollella P. Porous Gold: A New Frontier for Enzyme-Based Electrodes. NANOMATERIALS (BASEL, SWITZERLAND) 2020; 10:E722. [PMID: 32290306 PMCID: PMC7221854 DOI: 10.3390/nano10040722] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 04/01/2020] [Accepted: 04/08/2020] [Indexed: 12/23/2022]
Abstract
Porous gold (PG) layers modified electrodes have emerged as valuable enzyme support to realize multiple enzyme-based bioelectrochemical devices like biosensors, enzymatic fuel cells (EFCs), smart drug delivery devices triggered by enzyme catalyzed reactions, etc. PG films can be synthesized by using different methods such as dealloying, electrochemical (e.g., templated electrochemical deposition, self-templated electrochemical deposition, etc.) self-assembly and sputter deposition. This review aims to summarize the recent findings about PG synthesis and electrosynthesis, its characterization and application for enzyme-based electrodes used for biosensors and enzymatic fuel cells (EFCs) development.
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Affiliation(s)
- Paolo Bollella
- Department of Chemistry and Biomolecular Science, Clarkson University, Potsdam, 13699-5810 NY, USA
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Sha J, Si W, Xu B, Zhang S, Li K, Lin K, Shi H, Chen Y. Identification of Spherical and Nonspherical Proteins by a Solid-State Nanopore. Anal Chem 2018; 90:13826-13831. [DOI: 10.1021/acs.analchem.8b04136] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Jingjie Sha
- School of Mechanical Engineering, Southeast University, Nanjing 211189, China
- Jiangsu Key Laboratory for Design and Manufacture of Micro-nano Biomedical Instruments, Southeast University, Nanjing 211189, China
| | - Wei Si
- School of Mechanical Engineering, Southeast University, Nanjing 211189, China
- Jiangsu Key Laboratory for Design and Manufacture of Micro-nano Biomedical Instruments, Southeast University, Nanjing 211189, China
| | - Bing Xu
- School of Mechanical Engineering, Southeast University, Nanjing 211189, China
- Jiangsu Key Laboratory for Design and Manufacture of Micro-nano Biomedical Instruments, Southeast University, Nanjing 211189, China
| | - Shuai Zhang
- School of Mechanical Engineering, Southeast University, Nanjing 211189, China
- Jiangsu Key Laboratory for Design and Manufacture of Micro-nano Biomedical Instruments, Southeast University, Nanjing 211189, China
| | - Kun Li
- School of Mechanical Engineering, Southeast University, Nanjing 211189, China
- Jiangsu Key Laboratory for Design and Manufacture of Micro-nano Biomedical Instruments, Southeast University, Nanjing 211189, China
| | - Kabin Lin
- School of Mechanical Engineering, Southeast University, Nanjing 211189, China
- Jiangsu Key Laboratory for Design and Manufacture of Micro-nano Biomedical Instruments, Southeast University, Nanjing 211189, China
| | - Hongjiao Shi
- School of Mechanical Engineering, Southeast University, Nanjing 211189, China
- Jiangsu Key Laboratory for Design and Manufacture of Micro-nano Biomedical Instruments, Southeast University, Nanjing 211189, China
| | - Yunfei Chen
- School of Mechanical Engineering, Southeast University, Nanjing 211189, China
- Jiangsu Key Laboratory for Design and Manufacture of Micro-nano Biomedical Instruments, Southeast University, Nanjing 211189, China
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Peterson E, Joseph C, Peterson H, Bouwman R, Tang S, Cannon J, Sinniah K, Choi SK. Measuring the Adhesion Forces for the Multivalent Binding of Vancomycin-Conjugated Dendrimer to Bacterial Cell-Wall Peptide. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:7135-7146. [PMID: 29792710 DOI: 10.1021/acs.langmuir.8b01137] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Multivalent ligand-receptor interaction provides the fundamental basis for the hypothetical notion that high binding avidity relates to the strong force of adhesion. Despite its increasing importance in the design of targeted nanoconjugates, an understanding of the physical forces underlying the multivalent interaction remains a subject of urgent investigation. In this study, we designed three vancomycin (Van)-conjugated dendrimers G5(Van) n ( n = mean valency = 0, 1, 4) for bacterial targeting with generation 5 (G5) poly(amidoamine) dendrimer as a multivalent scaffold and evaluated both their binding avidity and physical force of adhesion to a bacterial model surface by employing surface plasmon resonance (SPR) spectroscopy and atomic force microscopy. The SPR experiment for these conjugates was performed in a biosensor chip surface immobilized with a bacterial cell-wall peptide Lys-d-Ala-d-Ala. Of these, G5(Van)4 bound most tightly with a KD of 0.34 nM, which represents an increase in avidity by 2 or 3 orders of magnitude relative to a monovalent conjugate G5(Van)1 or free vancomycin, respectively. By single-molecule force spectroscopy, we measured the adhesion force between G5(Van) n and the same cell-wall peptide immobilized on the surface. The distribution of adhesion forces increased in proportion to vancomycin valency with the mean force of 134 pN at n = 4 greater than 96 pN at n = 1 at a loading rate of 5200 pN/s. In summary, our results are strongly supportive of the positive correlation between the avidity and adhesion force in the multivalent interaction of vancomycin nanoconjugates.
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Affiliation(s)
- Elizabeth Peterson
- Department of Chemistry & Biochemistry , Calvin College , Grand Rapids , Michigan 49546 , United States
| | | | - Hannah Peterson
- Department of Chemistry & Biochemistry , Calvin College , Grand Rapids , Michigan 49546 , United States
| | - Rachael Bouwman
- Department of Chemistry & Biochemistry , Calvin College , Grand Rapids , Michigan 49546 , United States
| | | | | | - Kumar Sinniah
- Department of Chemistry & Biochemistry , Calvin College , Grand Rapids , Michigan 49546 , United States
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11
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Regulation of enzyme activity and stability through positional interaction with polyurethane nanofibers. Biochem Eng J 2017. [DOI: 10.1016/j.bej.2017.02.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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12
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Stine KJ. Application of Porous Materials to Carbohydrate Chemistry and Glycoscience. Adv Carbohydr Chem Biochem 2017; 74:61-136. [PMID: 29173727 DOI: 10.1016/bs.accb.2017.10.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
There is a growing interest in using a range of porous materials to meet research needs in carbohydrate chemistry and glycoscience in general. Among the applications of porous materials reviewed in this chapter, enrichment of glycans from biological samples prior to separation and analysis by mass spectrometry is a major emphasis. Porous materials offer high surface area, adjustable pore sizes, and tunable surface chemistry for interacting with glycans, by boronate affinity, hydrophilic interactions, molecular imprinting, and polar interactions. Among the materials covered in this review are mesoporous silica and related materials, porous graphitic carbon, mesoporous carbon, porous polymers, and nanoporous gold. In some applications, glycans are enzymatically or chemically released from glycoproteins or glycopeptides, and the porous materials have the advantage of size selectivity admitting only the glycans into the pores and excluding proteins. Immobilization of lectins onto porous materials of suitable pore size allows for the use of lectin-carbohydrate interactions in capture or separation of glycoproteins. Porous material surfaces modified with carbohydrates can be used for the selective capture of lectins. Controlled release of therapeutics from porous materials mediated by glycans has been reported, and so has therapeutic targeting using carbohydrate-modified porous particles. Additional applications of porous materials in glycoscience include their use in the supported synthesis of oligosaccharides and in the development of biosensors for glycans.
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Gregurec D, Velasco-Lozano S, Moya SE, Vázquez L, López-Gallego F. Force spectroscopy predicts thermal stability of immobilized proteins by measuring microbead mechanics. SOFT MATTER 2016; 12:8718-8725. [PMID: 27714304 DOI: 10.1039/c6sm01435f] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Optimal immobilization of enzymes on porous microbeads enables the fabrication of highly active and stable heterogeneous biocatalysts to implement biocatalysis in synthetic and analytical chemistry. However, empirical procedures for enzyme immobilization still prevail over rational ones because there is an unmet need for more comprehensive characterization techniques that aid to understand and trace the immobilization process. Here, we present the use of atomic force spectroscopy (AFS) as an innovative solution to indirectly characterize immobilized proteins on porous materials and monitor the immobilization process in real time. We investigate the mechanical properties of porous agarose microbeads immobilizing proteins by indenting a colloidal probe (silica microparticle) into a single bead. AFS demonstrates that the binding of proteins to the solid matrix of an agarose microbead alters its stiffness. Interestingly, we discovered that irreversible and multivalent immobilizations that make microbeads stiffer also stabilize the immobilized proteins against the temperature. Hence, we propose atomic force spectroscopy as a useful technique to indirectly unravel the stability of the immobilized enzymes investigating the mechanics of the heterogenous biocatalysts as a solid biomaterial beyond the intrinsic mechanics of the proteins.
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Affiliation(s)
- Danijela Gregurec
- Soft Matter Nanotechnology Group, CIC BiomaGUNE, Paseo Miramon 182, San Sebasitan-Donostia, 20009, Spain and RLE-Bioelectronics Research Group, Massachusetts Institute of Technology, 77 Massachusetts Ave 8-031, Cambridge, MA 02139, USA
| | - Susana Velasco-Lozano
- Heterogeneus Biocatalysis Group, CIC BiomaGUNE, Paseo Miramon 182, San Sebasitan-Donostia, 20009, Spain.
| | - Sergio E Moya
- Soft Matter Nanotechnology Group, CIC BiomaGUNE, Paseo Miramon 182, San Sebasitan-Donostia, 20009, Spain
| | - Luis Vázquez
- Instituto de Ciencia de Materiales de Madrid (CSIC), Campus de Cantoblanco, C\Sor Juana Inés de la Cruz 3, Madrid, 28049, Spain
| | - Fernando López-Gallego
- Heterogeneus Biocatalysis Group, CIC BiomaGUNE, Paseo Miramon 182, San Sebasitan-Donostia, 20009, Spain. and IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
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14
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Nanoporous Gold for Enzyme Immobilization. Methods Mol Biol 2016. [PMID: 27770413 DOI: 10.1007/978-1-4939-6499-4_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Nanoporous gold (NPG) is a material of emerging interest for immobilization of biomolecules, especially enzymes. The material provides a high surface area form of gold that is suitable for physisorption or for covalent modification by self-assembled monolayers. The material can be used as a high surface area electrode and with immobilized enzymes can be used for amperometric detection schemes. NPG can be prepared in a variety of formats from alloys containing between 20 and 50 % atomic composition of gold and less noble element(s) by dealloying procedures. Materials resembling NPG can be prepared by hydrothermal and electrodeposition methods. Related high surface area gold structures have been prepared using templating approaches. Covalent enzyme immobilization can be achieved by first forming a self-assembled monolayer on NPG bearing a terminal reactive functional group followed by conjugation to the enzyme through amide linkages to lysine residues. Enzymes can also be entrapped by physisorption or immobilized by electrostatic interactions.
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15
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Funari R, Della Ventura B, Altucci C, Offenhäusser A, Mayer D, Velotta R. Single Molecule Characterization of UV-Activated Antibodies on Gold by Atomic Force Microscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:8084-91. [PMID: 27444884 DOI: 10.1021/acs.langmuir.6b02218] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The interaction between proteins and solid surfaces can influence their conformation and therefore also their activity and affinity. These interactions are highly specific for the respective combination of proteins and solids. Consequently, it is desirable to investigate the conformation of proteins on technical surfaces, ideally at single molecule level, and to correlate the results with their activity. This is in particular true for biosensors where the conformation-dependent target affinity of an immobilized receptor determines the sensitivity of the sensor. Here, we investigate for the first time the immobilization and orientation of antibodies (Abs) photoactivated by a photonic immobilization technique (PIT), which has previously demonstrated to enhance binding capabilities of antibody receptors. The photoactivated immunoglobulins are immobilized on ultrasmooth template stripped gold films and investigated by atomic force microscopy (AFM) at the level of individual molecules. The observed protein orientations are compared with results of nonactivated antibodies adsorbed on similar gold films and mica reference samples. We find that the behavior of Abs is similar for mica and gold when the protein are not treated (physisorption), whereas smaller contact area and larger heights are measured when Abs are treated (PIT). This is explained by assuming that the activated antibodies tend to be more upright compared with nonirradiated ones, thereby providing a better exposure of the binding sites. This finding matches the observed enhancement of Abs binding efficiency when PIT is used to functionalize gold surface of QCM-based biosensors.
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Affiliation(s)
- R Funari
- Department of Physics Ettore Pancini, Università di Napoli Federico II , via Cintia, I-80126 Napoli, Italy
| | - B Della Ventura
- Department of Physics Ettore Pancini, Università di Napoli Federico II , via Cintia, I-80126 Napoli, Italy
| | - C Altucci
- Department of Physics Ettore Pancini, Università di Napoli Federico II , via Cintia, I-80126 Napoli, Italy
| | - A Offenhäusser
- Peter Grünberg Institute (PGI-8) and Institute of Complex Systems (ICS-8), Forschungszentrum Jülich GmbH , 52428 Jülich, Germany
| | - D Mayer
- Peter Grünberg Institute (PGI-8) and Institute of Complex Systems (ICS-8), Forschungszentrum Jülich GmbH , 52428 Jülich, Germany
| | - R Velotta
- Department of Physics Ettore Pancini, Università di Napoli Federico II , via Cintia, I-80126 Napoli, Italy
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Menti C, Henriques JAP, Missell FP, Roesch-Ely M. Antibody-based magneto-elastic biosensors: potential devices for detection of pathogens and associated toxins. Appl Microbiol Biotechnol 2016; 100:6149-6163. [DOI: 10.1007/s00253-016-7624-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 05/02/2016] [Accepted: 05/04/2016] [Indexed: 11/29/2022]
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17
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An overview of dealloyed nanoporous gold in bioelectrochemistry. Bioelectrochemistry 2016; 109:117-26. [DOI: 10.1016/j.bioelechem.2015.12.008] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Revised: 12/23/2015] [Accepted: 12/30/2015] [Indexed: 02/07/2023]
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18
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Alla AJ, D' Andrea FB, Bhattarai JK, Cooper JA, Tan YH, Demchenko AV, Stine KJ. Selective capture of glycoproteins using lectin-modified nanoporous gold monolith. J Chromatogr A 2015; 1423:19-30. [PMID: 26554297 DOI: 10.1016/j.chroma.2015.10.060] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Revised: 10/14/2015] [Accepted: 10/17/2015] [Indexed: 11/25/2022]
Abstract
The surface of nanoporous gold (np-Au) monoliths was modified via a flow method with the lectin Concanavalin A (Con A) to develop a substrate for separation and extraction of glycoproteins. Self-assembled monolayers (SAMs) of α-lipoic acid (LA) on the np-Au monoliths were prepared followed by activation of the terminal carboxyl groups to create amine reactive esters that were utilized in the immobilization of Con A. Thermogravimetric analysis (TGA) was used to determine the surface coverages of LA and Con A on np-Au monoliths which were found to be 1.31×10(18) and 1.85×10(15)moleculesm(-2), respectively. An in situ solution depletion method was developed that enabled surface coverage characterization without damaging the substrate and suggesting the possibility of regeneration. Using this method, the surface coverages of LA and Con A were found to be 0.989×10(18) and 1.32×10(15)moleculesm(-2), respectively. The selectivity of the Con A-modified np-Au monolith for the high mannose-containing glycoprotein ovalbumin (OVA) versus negative control non-glycosylated bovine serum albumin (BSA) was demonstrated by the difference in the ratio of the captured molecules to the immobilized Con A molecules, with OVA:Con A=2.3 and BSA:Con A=0.33. Extraction of OVA from a 1:3 mole ratio mixture with BSA was demonstrated by the greater amount of depletion of OVA concentration during the circulation with the developed substrate. A significant amount of captured OVA was eluted using α-methyl mannopyranoside as a competitive ligand. This work is motivated by the need to develop new materials for chromatographic separation and extraction substrates for use in preparative and analytical procedures in glycomics.
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Affiliation(s)
- Allan J Alla
- Department of Chemistry and Biochemistry, One University Boulevard, University of Missouri-St. Louis, Saint Louis, MO 63121 USA; Center for Nanoscience, One University Boulevard, University of Missouri-St. Louis, Saint Louis, MO 63121, USA
| | - Felipe B D' Andrea
- Department of Chemistry and Biochemistry, One University Boulevard, University of Missouri-St. Louis, Saint Louis, MO 63121 USA; Center for Nanoscience, One University Boulevard, University of Missouri-St. Louis, Saint Louis, MO 63121, USA
| | - Jay K Bhattarai
- Department of Chemistry and Biochemistry, One University Boulevard, University of Missouri-St. Louis, Saint Louis, MO 63121 USA; Center for Nanoscience, One University Boulevard, University of Missouri-St. Louis, Saint Louis, MO 63121, USA
| | - Jared A Cooper
- Department of Chemistry and Biochemistry, One University Boulevard, University of Missouri-St. Louis, Saint Louis, MO 63121 USA; Center for Nanoscience, One University Boulevard, University of Missouri-St. Louis, Saint Louis, MO 63121, USA
| | - Yih Horng Tan
- Department of Chemistry and Biochemistry, One University Boulevard, University of Missouri-St. Louis, Saint Louis, MO 63121 USA; Center for Nanoscience, One University Boulevard, University of Missouri-St. Louis, Saint Louis, MO 63121, USA
| | - Alexei V Demchenko
- Department of Chemistry and Biochemistry, One University Boulevard, University of Missouri-St. Louis, Saint Louis, MO 63121 USA
| | - Keith J Stine
- Department of Chemistry and Biochemistry, One University Boulevard, University of Missouri-St. Louis, Saint Louis, MO 63121 USA; Center for Nanoscience, One University Boulevard, University of Missouri-St. Louis, Saint Louis, MO 63121, USA.
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19
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Daggumati P, Matharu Z, Wang L, Seker E. Biofouling-Resilient Nanoporous Gold Electrodes for DNA Sensing. Anal Chem 2015; 87:8618-22. [DOI: 10.1021/acs.analchem.5b02969] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Pallavi Daggumati
- Department of Electrical
and Computer Engineering, University of California, Davis, California 95616, United States
| | - Zimple Matharu
- Department of Electrical
and Computer Engineering, University of California, Davis, California 95616, United States
| | - Ling Wang
- Department of Electrical
and Computer Engineering, University of California, Davis, California 95616, United States
| | - Erkin Seker
- Department of Electrical
and Computer Engineering, University of California, Davis, California 95616, United States
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20
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Development of Monolithic Column Materials for the Separation and Analysis of Glycans. CHROMATOGRAPHY 2015. [DOI: 10.3390/chromatography2010020] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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21
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Kurtulus O, Daggumati P, Seker E. Molecular release from patterned nanoporous gold thin films. NANOSCALE 2014; 6:7062-71. [PMID: 24842586 DOI: 10.1039/c4nr01288g] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Nanostructured materials have shown significant potential for biomedical applications that require high loading capacity and controlled release of drugs. Nanoporous gold (np-Au), produced by an alloy corrosion process, is a promising novel material that benefits from compatibility with microfabrication, tunable pore morphology, electrical conductivity, well-established gold-thiol conjugate chemistry, and biocompatibility. While np-Au's non-biological applications are abundant, its performance in the biomedical field is nascent. In this work, we employ a combination of techniques including nanoporous thin film synthesis, quantitative electron microscopy, fluorospectrometry, and electrochemical surface characterization to study loading capacity and molecular release kinetics as a function of film properties and discuss underlying mechanisms. The sub-micron-thick sputter-coated nanoporous gold films provide small-molecule loading capacities up to 1.12 μg cm(-2) and molecular release half-lives between 3.6 hours to 12.8 hours. A systematic set of studies reveals that effective surface area of the np-Au thin films on glass substrates plays the largest role in determining loading capacity. The release kinetics on the other hand depends on a complex interplay of micro- and nano-scale morphological features.
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Affiliation(s)
- Ozge Kurtulus
- Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95616, USA
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22
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Xiao X, Li H, Wang M, Zhang K, Si P. Examining the effects of self-assembled monolayers on nanoporous gold based amperometric glucose biosensors. Analyst 2014; 139:488-94. [DOI: 10.1039/c3an01670f] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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23
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Shi L, Chu Z, Liu Y, Peng J, Jin W. Three-dimensional porous microarray of gold modified electrode for ultrasensitive and simultaneous assay of various cancer biomarkers. J Mater Chem B 2014; 2:2658-2665. [DOI: 10.1039/c4tb00016a] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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24
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Luo QY, Lin Y, Peng J, Liu SL, Zhang ZL, Tian ZQ, Pang DW. Evaluation of nonspecific interactions between quantum dots and proteins. Phys Chem Chem Phys 2014; 16:7677-80. [DOI: 10.1039/c4cp00572d] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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25
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Tan YH, Terrill SE, Paranjape GS, Stine KJ, Nichols MR. The influence of gold surface texture on microglia morphology and activation. Biomater Sci 2013; 2:110-120. [PMID: 32481813 DOI: 10.1039/c3bm60096c] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Microglial cells play a critical role in the propagation of neuroinflammation in the central nervous system. Microglia sense and respond to environmental signals including chemical, physical and biological cues from the surrounding cell/tissue components. In this project, our goal was to examine the effects of surface texture on BV-2 microglia morphology and function by comparing flat and nanoporous gold (np-Au) surfaces to the more conventional glass. The biocompatibility of np-Au with microglia was evaluated using functional cell assays and high resolution imaging with scanning electron microscopy (SEM). Microglia seeded on glass, ultra-flat gold (UF-Au), ultra-thin (UT) np-Au and np-Au monolith were adherent to all surfaces and their viability was not compromised as assessed by multiple toxicity assays. SEM revealed detailed morphological characteristics of adherent microglia and indicated few dramatic changes as a result of the different surfaces. Microglia proliferation was hampered by np-Au monolith but less by UT np-Au and not at all on UF-Au or glass. Microglial activation, measured by tumor necrosis factor α (TNFα) production, was fully functional (and equivalent) on all gold surfaces compared to glass. The present findings should help further the understanding of basic microglia biology on textured surfaces and more fully evaluate np-Au as a multi-functional biocompatible material. The knowledge obtained and technology developed will have a significant impact in the fabrication of nanoelectronic devices, chemical sensor development, porous nanostructured materials for BioMEMs/NEMs integration, and functional biomaterial coatings for drug delivery.
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Affiliation(s)
- Yih Horng Tan
- Department of Chemistry and Biochemistry and Center for Nanoscience, University of Missouri-St. Louis, One University Boulevard, St. Louis, Missouri 63121, USA.
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26
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Tan YH, Fujikawa K, Pornsuriyasak P, Alla AJ, Ganesh NV, Demchenko AV, Stine KJ. Lectin-carbohydrate interactions on nanoporous gold monoliths. NEW J CHEM 2013; 37:2150-2165. [PMID: 24883017 PMCID: PMC4038695 DOI: 10.1039/c3nj00253e] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Monoliths of nanoporous gold (np-Au) were modified with self-assembled monolayers of octadecanethiol (C18-SH), 8-mercaptooctyl α-D-mannopyranoside (αMan-C8-SH), and 8-mercapto-3,6-dioxaoctanol (HO-PEG2-SH), and the loading was assessed using thermogravimetric analysis (TGA). Modification with mixed SAMs containing αMan-C8-SH (at a 0.20 mole fraction in the SAM forming solution) with either octanethiol or HO-PEG2-SH was also investigated. The np-Au monoliths modified with αMan-C8-SH bind the lectin Concanavalin A (Con A), and the additional mass due to bound protein was assessed using TGA analysis. A comparison of TGA traces measured before and after exposure of HO-PEG2-SH modified np-Au to Con A showed that the non-specific binding of Con A was minimal. In contrast, np-Au modified with octanethiol showed a significant mass loss due to non-specifically adsorbed Con A. A significant mass loss was also attributed to binding of Con A to bare np-Au monoliths. TGA revealed a mass loss due to the binding of Con A to np-Au monoliths modified with pure αMan-C8-SH. The use of mass losses determined by TGA to compare the binding of Con A to np-Au monoliths modified by mixed SAMs of αMan-C8-SH and either octanethiol or HO-PEG2-SH revealed that binding to mixed SAM modified surfaces is specific for the mixed SAMs with HO-PEG2-SH but shows a significant contribution from non-specific adsorption for the mixed SAMs with octanethiol. Minimal adsorption of immunoglobulin G (IgG) and peanut agglutinin (PNA) towards the mannoside modified np-Au monoliths was demonstrated. A greater mass loss was found for Con A bound onto the monolith than for either IgG or PNA, signifying that the mannose presenting SAMs in np-Au retain selectivity for Con A. TGA data also provide evidence that Con A bound to the αMan-C8-SH modified np-Au can be eluted by flowing a solution of methyl α-D-mannopyranoside through the structure. The presence of Con A proteins on the modified np-Au surface was also confirmed using atomic force microscopy (AFM). The results highlight the potential for application of carbohydrate modified np-Au monoliths to glycoscience and glycotechnology and demonstrate that they can be used for capture and release of carbohydrate binding proteins in significant quantities.
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Affiliation(s)
- Yih Horng Tan
- Department of Chemistry and Biochemistry, University of Missouri – Saint Louis, Saint Louis, MO 63121, USA
- UM-St. Louis Center for Nanoscience, University of Missouri – Saint Louis, Saint Louis, MO 63121, USA
| | - Kohki Fujikawa
- Department of Chemistry and Biochemistry, University of Missouri – Saint Louis, Saint Louis, MO 63121, USA
| | - Papapida Pornsuriyasak
- Department of Chemistry and Biochemistry, University of Missouri – Saint Louis, Saint Louis, MO 63121, USA
| | - Allan J. Alla
- Department of Chemistry and Biochemistry, University of Missouri – Saint Louis, Saint Louis, MO 63121, USA
- UM-St. Louis Center for Nanoscience, University of Missouri – Saint Louis, Saint Louis, MO 63121, USA
| | - N. Vijaya Ganesh
- Department of Chemistry and Biochemistry, University of Missouri – Saint Louis, Saint Louis, MO 63121, USA
| | - Alexei V. Demchenko
- Department of Chemistry and Biochemistry, University of Missouri – Saint Louis, Saint Louis, MO 63121, USA
| | - Keith J. Stine
- Department of Chemistry and Biochemistry, University of Missouri – Saint Louis, Saint Louis, MO 63121, USA
- UM-St. Louis Center for Nanoscience, University of Missouri – Saint Louis, Saint Louis, MO 63121, USA
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27
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Pandey B, Tan YH, Parameswar AR, Pornsuriyasak P, Demchenko AV, Stine KJ. Electrochemical characterization of globotriose-containing self-assembled monolayers on nanoporous gold and their binding of soybean agglutinin. Carbohydr Res 2013; 373:9-17. [PMID: 23545324 PMCID: PMC3615452 DOI: 10.1016/j.carres.2012.09.021] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Revised: 09/25/2012] [Accepted: 09/26/2012] [Indexed: 01/08/2023]
Abstract
Self-assembled monolayers (SAMs) of α-D-Gal-(1→4)-β-D-Gal-(1→4)-β-D-Glc-mercaptooctane (globotriose, Gb3-C8-SH) were prepared both as single-component SAMs and as mixed SAMs with either octanethiol (OCT) or 8-mercapto-3,6-dioxaoctanol (HO-PEG2-SH), on flat gold and on nanoporous gold (NPG) electrodes. The binding of soybean agglutinin (SBA) to the globotriose (Gb3) unit in the SAMs was then studied using electrochemical impedance spectroscopy (EIS), which is a label free method found to be quite sensitive to SAM composition and to the differences in SAM structure on NPG versus on flat Au. The affinity of SBA to the mixed SAM of HO-PEG2-SH and Gb3-C8-SH on NPG is found to be greater on NPG than on flat gold, and indicates a potential advantage for NPG as a substrate. The SAMs of HO-PEG2-SH were found to resist protein adsorption on either NPG or flat gold. The non-specific adsorption of SBA to OCT SAMs on flat Au was observed in EIS by the increase in charge transfer resistance; whereas, the increase seen on the NPG surface was smaller, and suggests that EIS measurements on NPG are less affected by non-specific protein adsorption. Atomic force microscopy (AFM) images of the SBA binding to mixed SAM of HO-PEG2-SH and Gb3-C8-SH on NPG showed a greater number of proteins on top of the OCT containing SAMs.
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Affiliation(s)
- Binod Pandey
- Department of Chemistry and Biochemistry, University of Missouri – Saint Louis, Saint Louis, MO 63121, USA
- Center for Nanoscience, University of Missouri – Saint Louis, Saint Louis, MO 63121, USA
| | - Yih Horng Tan
- Department of Chemistry and Biochemistry, University of Missouri – Saint Louis, Saint Louis, MO 63121, USA
- Center for Nanoscience, University of Missouri – Saint Louis, Saint Louis, MO 63121, USA
| | - Archana R. Parameswar
- Department of Chemistry and Biochemistry, University of Missouri – Saint Louis, Saint Louis, MO 63121, USA
| | - Papapida Pornsuriyasak
- Department of Chemistry and Biochemistry, University of Missouri – Saint Louis, Saint Louis, MO 63121, USA
| | - Alexei V. Demchenko
- Department of Chemistry and Biochemistry, University of Missouri – Saint Louis, Saint Louis, MO 63121, USA
| | - Keith J. Stine
- Department of Chemistry and Biochemistry, University of Missouri – Saint Louis, Saint Louis, MO 63121, USA
- Center for Nanoscience, University of Missouri – Saint Louis, Saint Louis, MO 63121, USA
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28
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Brun EM, Puchades R, Maquieira Á. Gold, Carbon, and Aluminum Low-Reflectivity Compact Discs as Microassaying Platforms. Anal Chem 2013; 85:4178-86. [DOI: 10.1021/ac4004985] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Eva M. Brun
- Centro de
Reconocimiento Molecular y Desarrollo Tecnológico,
Departamento de Química, Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia,
Spain
| | - Rosa Puchades
- Centro de
Reconocimiento Molecular y Desarrollo Tecnológico,
Departamento de Química, Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia,
Spain
| | - Ángel Maquieira
- Centro de
Reconocimiento Molecular y Desarrollo Tecnológico,
Departamento de Química, Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia,
Spain
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29
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Abstract
Nanoporous gold prepared by dealloying Au:Ag alloys has recently become an attractive material in the field of analytical chemistry. This conductive material has an open, 3D porous framework consisting of nanosized pores and ligaments with surface areas that are 10s to 100s of times larger than planar gold of an equivalent geometric area. The high surface area coupled with an open pore network makes nanoporous gold an ideal support for the development of chemical sensors. Important attributes include conductivity, high surface area, ease of preparation and modification, tunable pore size, and a bicontinuous open pore network. In this paper, the fabrication, characterization, and applications of nanoporous gold in chemical sensing are reviewed specifically as they relate to the development of immunosensors, enzyme-based biosensors, DNA sensors, Raman sensors, and small molecule sensors.
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30
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Qiu H, Dong X, Huang X. Design of nanoporous metals with bimodal pore size distributions for enhanced biosensing. NANOSCALE 2012; 4:4492-4497. [PMID: 22538347 DOI: 10.1039/c2nr30460k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Nanoporous gold (np-Au) has shown great potential in catalysis, plasmonics, sensing, etc. In this work, by two-step dealloying a well-designed AuAgAl ternary precursor alloy, np-Au with bimodal ligament/pore size distributions is successfully fabricated. The first dealloying in HCl solution removes Al and generates a nanoporous AuAg alloy which would be mildly annealed at 200 °C for 30 min to homogenize the alloy ligament and enlarge the ligament/pore size. Next, the nanoporous AuAg alloy is further dealloyed in a HNO(3) solution to etch Ag and fabricate np-Au with a hierarchical microstructure. This novel bimodal np-Au is demonstrated to exhibit enhanced electrocatalytic activity towards H(2)O(2) reduction and be a better support for the fabrication of an oxidase-based biosensor compared with normal np-Au, with a uniform pore/ligament size of 30-40 nm. In a proof-of-concept study, a sensitive glucose biosensor with a linear range up to 21 mM is fabricated by immobilization of glucose oxidase on the bimodal np-Au.
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Affiliation(s)
- Huajun Qiu
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China.
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31
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Tan YH, Davis JA, Fujikawa K, Ganesh NV, Demchenko AV, Stine KJ. Surface area and pore size characteristics of nanoporous gold subjected to thermal, mechanical, or surface modification studied using gas adsorption isotherms, cyclic voltammetry, thermogravimetric analysis, and scanning electron microscopy. ACTA ACUST UNITED AC 2012; 22:6733-6745. [PMID: 22822294 DOI: 10.1039/c2jm16633j] [Citation(s) in RCA: 113] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Nitrogen adsorption/desorption isotherms are used to investigate the Brunauer, Emmett, and Teller (BET) surface area and Barrett-Joyner-Halenda (BJH) pore size distribution of physically modified, thermally annealed, and octadecanethiol functionalized np-Au monoliths. We present the full adsorption-desorption isotherms for N(2) gas on np-Au, and observe type IV isotherms and type H1 hysteresis loops. The evolution of the np-Au under various thermal annealing treatments was examined using scanning electron microscopy (SEM). The images of both the exterior and interior of the thermally annealed np-Au show that the porosity of all free standing np-Au structures decreases as the heat treatment temperature increases. The modification of the np-Au surface with a self-assembled monolayer (SAM) of C(18)-SH (coverage of 2.94 × 10(14) molecules cm(-2) based from the decomposition of the C(18)-SH using thermogravimetric analysis (TGA)), was found to reduce the strength of the interaction of nitrogen gas with the np-Au surface, as reflected by a decrease in the 'C' parameter of the BET equation. From cyclic voltammetry studies, we found that the surface area of the np-Au monoliths annealed at elevated temperatures followed the same trend with annealing temperature as found in the BET surface area study and SEM morphology characterization. The study highlights the ability to control free-standing nanoporous gold monoliths with high surface area, and well-defined, tunable pore morphology.
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Affiliation(s)
- Yih Horng Tan
- Department of Chemistry and Biochemistry, University of Missouri - Saint Louis, Saint Louis, MO, 63121, USA
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32
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Pandey B, Tan YH, Fujikawa K, Demchenko AV, Stine KJ. Comparative Study of the Binding of Concanavalin A to Self-Assembled Monolayers Containing a Thiolated α-Mannoside on Flat Gold and on Nanoporous Gold. J Carbohydr Chem 2012; 31:466-503. [PMID: 23519474 PMCID: PMC3601678 DOI: 10.1080/07328303.2012.683909] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
We have prepared SAMs containing 8-mercaptooctyl α-D-mannopyranoside, either as a single component or in mixed SAMs with n-octanethiol on flat gold surfaces and on nanoporous gold. Electrochemical impedance spectroscopy showed that the mixed SAMs on flat gold surfaces showed the highest Con A binding near 1:9 solution molar ratio of thiolatedα-mannoside to n-octanethiol whereas those on NPG showed the highest response at 1:19 solution molar ratio of thiolated α-mannoside to n-octanethiol. Atomic force microscopy was employed to image the monolayers, and also to image the bound Con A protein.
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Affiliation(s)
- Binod Pandey
- Department of Chemistry and Biochemistry, University of Missouri - Saint Louis, Saint Louis, MO 63121, USA ; Center for Nanoscience, University of Missouri - Saint Louis, Saint Louis, MO 63121, USA
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33
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Doherty CM, Gao Y, Marmiroli B, Amenitsch H, Lisi F, Malfatti L, Okada K, Takahashi M, Hill AJ, Innocenzi P, Falcaro P. Microfabrication of mesoporous silica encapsulated enzymes using deep X-ray lithography. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c2jm32863a] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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