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Anthi J, Vaněčková E, Spasovová M, Houska M, Vrabcová M, Vogelová E, Holubová B, Vaisocherová-Lísalová H, Kolivoška V. Probing charge transfer through antifouling polymer brushes by electrochemical methods: The impact of supporting self-assembled monolayer chain length. Anal Chim Acta 2023; 1276:341640. [PMID: 37573118 DOI: 10.1016/j.aca.2023.341640] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 07/10/2023] [Accepted: 07/17/2023] [Indexed: 08/14/2023]
Abstract
Ultrathin surface-tethered polymer brushes represent attractive platforms for a wide range of sensing applications in strategically vital areas such as medicine, forensics, or security. The recent trends in such developments towards "real world conditions" highlighted the role of zwitterionic poly(carboxybetaine) (pCB) brushes which provide excellent antifouling properties combined with bio-functionalization capacity. Highly dense pCB brushes are usually prepared by the "grafting from" polymerization triggered by initiators on self-assembled monolayers (SAMs). Here, multi-methodological experimental studies are pursued to elucidate the impact of the alkanethiolate SAM chain length (C6, C8 and C11) on structural and functional properties of antifouling poly(carboxybetaine methacrylamide) (pCBMAA) brush. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in a custom-made 3D printed cell employing [Ru(NH3)6]3+/2+ redox probe were used to investigate penetrability of SAM/pCBMAA bilayers for small molecules and interfacial charge transfer characteristics. The biofouling resistance of pCBMAA brushes was characterized by surface plasmon resonance; ellipsometry and FT-IRRAS spectroscopy were used to determine swelling and relative density of the brushes synthesized from initiator-bearing SAMs with varied carbon chain length. The SAM length was found to have a substantial impact on all studied characteristics; the highest value of charge transfer resistance (Rct) was observed for denser pCBMAA on longer-chain (C11) SAM when compared to shorter (C8/C6) SAMs. The observed high value of Rct for C11 implies a limitation for the analytical performance of electrochemical sensing methods. At the same time, the pCBMAA brushes on C11 SAM exhibited the best bio-fouling resistance among inspected systems. This demonstrates that proper selection of supporting structures for brushes is critical in the design of these assemblies for biosensing applications.
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Affiliation(s)
- Judita Anthi
- FZU - Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 182 00, Prague, Czech Republic; Department of Biochemistry and Microbiology, University of Chemistry and Technology Prague, Technická 3, 166 28, Prague, Czech Republic
| | - Eva Vaněčková
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 3, 182 23, Prague, Czech Republic
| | - Monika Spasovová
- FZU - Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 182 00, Prague, Czech Republic
| | - Milan Houska
- FZU - Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 182 00, Prague, Czech Republic
| | - Markéta Vrabcová
- FZU - Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 182 00, Prague, Czech Republic
| | - Eva Vogelová
- FZU - Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 182 00, Prague, Czech Republic
| | - Barbora Holubová
- Department of Biochemistry and Microbiology, University of Chemistry and Technology Prague, Technická 3, 166 28, Prague, Czech Republic
| | - Hana Vaisocherová-Lísalová
- FZU - Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 182 00, Prague, Czech Republic.
| | - Viliam Kolivoška
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 3, 182 23, Prague, Czech Republic.
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Zhou X, Zheng B. Surface modification for improving immunoassay sensitivity. LAB ON A CHIP 2023; 23:1151-1168. [PMID: 36636910 DOI: 10.1039/d2lc00811d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Immunoassays are widely performed in many fields such as biomarker discovery, proteomics, drug development, and clinical diagnosis. There is a growing need for high sensitivity of immunoassays to detect low abundance analytes. As a result, great effort has been made to improve the quality of surfaces, on which the immunoassay is performed. In this review article, we summarize the recent progress in surface modification strategies for improving the sensitivity of immunoassays. The surface modification strategies can be categorized into two groups: antifouling coatings to reduce background noise and nanostructured surfaces to amplify the signals. The first part of the review summarizes the common antifouling coating techniques to prevent nonspecific binding and reduce background noise. The techniques include hydrophilic polymer based self-assembled monomers, polymer brushes, and surface attached hydrogels, and omniphobicity based perfluorinated surfaces. In the second part, some common nanostructured surfaces to amplify the specific detection signals are introduced, including nanoparticle functionalized surfaces, two dimensional (2D) nanoarrays, and 2D nanomaterial coatings. The third part discusses the surface modification techniques for digital immunoassays. In the end, the challenges and the future perspectives of the surface modification techniques for immunoassays are presented.
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Affiliation(s)
- Xiaohu Zhou
- Institute for Cell Analysis, Shenzhen Bay Laboratory, Shenzhen 518132, China.
| | - Bo Zheng
- Institute for Cell Analysis, Shenzhen Bay Laboratory, Shenzhen 518132, China.
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Andersson J, Järlebark J, KK S, Schaefer A, Hailes R, Palasingh C, Santoso B, Vu VT, Huang CJ, Westerlund F, Dahlin A. Polymer Brushes on Silica Nanostructures Prepared by Aminopropylsilatrane Click Chemistry: Superior Antifouling and Biofunctionality. ACS APPLIED MATERIALS & INTERFACES 2023; 15:10228-10239. [PMID: 36765467 PMCID: PMC9951205 DOI: 10.1021/acsami.2c21168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Accepted: 01/31/2023] [Indexed: 06/18/2023]
Abstract
In nanobiotechnology, the importance of controlling interactions between biological molecules and surfaces is paramount. In recent years, many devices based on nanostructured silicon materials have been presented, such as nanopores and nanochannels. However, there is still a clear lack of simple, reliable, and efficient protocols for preventing and controlling biomolecule adsorption in such structures. In this work, we show a simple method for passivation or selective biofunctionalization of silica, without the need for polymerization reactions or vapor-phase deposition. The surface is simply exposed stepwise to three different chemicals over the course of ∼1 h. First, the use of aminopropylsilatrane is used to create a monolayer of amines, yielding more uniform layers than conventional silanization protocols. Second, a cross-linker layer and click chemistry are used to make the surface reactive toward thiols. In the third step, thick and dense poly(ethylene glycol) brushes are prepared by a grafting-to approach. The modified surfaces are shown to be superior to existing options for silica modification, exhibiting ultralow fouling (a few ng/cm2) after exposure to crude serum. In addition, by including a fraction of biotinylated polymer end groups, the surface can be functionalized further. We show that avidin can be detected label-free from a serum solution with a selectivity (compared to nonspecific binding) of more than 98% without the need for a reference channel. Furthermore, we show that our method can passivate the interior of 150 nm × 100 nm nanochannels in silica, showing complete elimination of adsorption of a sticky fluorescent protein. Additionally, our method is shown to be compatible with modifications of solid-state nanopores in 20 nm thin silicon nitride membranes and reduces the noise in the ion current. We consider these findings highly important for the broad field of nanobiotechnology, and we believe that our method will be very useful for a great variety of surface-based sensors and analytical devices.
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Affiliation(s)
- John Andersson
- Department
of Chemistry and Chemical Engineering, Chalmers
University of Technology, 41296 Gothenburg, Sweden
| | - Julia Järlebark
- Department
of Chemistry and Chemical Engineering, Chalmers
University of Technology, 41296 Gothenburg, Sweden
| | - Sriram KK
- Department
of Life Sciences, Chalmers University of
Technology, 41296 Gothenburg, Sweden
| | - Andreas Schaefer
- Department
of Chemistry and Chemical Engineering, Chalmers
University of Technology, 41296 Gothenburg, Sweden
| | - Rebekah Hailes
- Department
of Chemistry and Chemical Engineering, Chalmers
University of Technology, 41296 Gothenburg, Sweden
| | - Chonnipa Palasingh
- Department
of Chemistry and Chemical Engineering, Chalmers
University of Technology, 41296 Gothenburg, Sweden
| | - Bagus Santoso
- Department
of Chemistry and Chemical Engineering, Chalmers
University of Technology, 41296 Gothenburg, Sweden
| | - Van-Truc Vu
- Department
of Chemical and Materials Engineering, National
Central University, Taoyuan 32023, Taiwan
| | - Chun-Jun Huang
- Department
of Chemical and Materials Engineering, National
Central University, Taoyuan 32023, Taiwan
- R&D
Center for Membrane Technology, Chung Yuan
Christian University, Taoyuan 32023, Taiwan
- NCU-Covestro
Research Center, National Central University, Jhong-Li, Taoyuan 32023, Taiwan
| | - Fredrik Westerlund
- Department
of Life Sciences, Chalmers University of
Technology, 41296 Gothenburg, Sweden
| | - Andreas Dahlin
- Department
of Chemistry and Chemical Engineering, Chalmers
University of Technology, 41296 Gothenburg, Sweden
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