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Luongo A, von Stockert AR, Scherag FD, Brandstetter T, Biesalski M, Rühe J. Controlling Fluorescent Readout in Paper-based Analytical Devices. ACS Biomater Sci Eng 2023; 9:6379-6389. [PMID: 37875260 PMCID: PMC10649804 DOI: 10.1021/acsbiomaterials.3c00736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 09/14/2023] [Indexed: 10/26/2023]
Abstract
Paper is an ideal candidate for the development of new disposable diagnostic devices because it is a low-cost material, allows transport of the liquid on the device by capillary action, and is environmentally friendly. Today, colorimetric analysis is most often used as a detection method for rapid tests (test strips or lateral flow devices) but usually gives only qualitative results and is limited by a relatively high detection threshold. Here, we describe studies using fluorescence as a readout tool for paper-based diagnostics. We study how the optical readout is affected by light transmission, scattering, and fluorescence as a function of paper characteristics such as thickness (grammage), water content, autofluorescence, and paper type/composition. We show that paper-based fluorescence analysis allows better optical readout compared to that of nitrocellulose, which is currently the material of choice in colorimetric assays. To reduce the loss of analyte molecules (e.g., proteins) due to adsorption to the paper surface, we coat the paper fibers with a protein-repellent hydrogel. For this purpose, we use hydrophilic copolymers consisting of N,N-dimethyl acrylamide and a benzophenone-based cross-linker, which are photochemically transformed into a fiber-attached polymer hydrogel on the paper fiber surfaces in situ. We show that the combination of fluorescence detection and the use of a protein-repellent coating enables sensitive paper-based analysis. Finally, the success of the strategy is demonstrated by using a simple LFD application as an example.
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Affiliation(s)
- Anna Luongo
- Laboratory
for Chemistry & Physics of Interfaces, Department of Microsystems
Engineering (IMTEK), Albert-Ludwigs-Universität
Freiburg, Freiburg 79110, Germany
- Freiburg
Institute for Interactive Materials and Bioinspired Technologies (FIT), Albert-Ludwigs-Universität Freiburg, Freiburg 79110, Germany
| | | | - Frank D. Scherag
- Laboratory
for Chemistry & Physics of Interfaces, Department of Microsystems
Engineering (IMTEK), Albert-Ludwigs-Universität
Freiburg, Freiburg 79110, Germany
- Freiburg
Institute for Interactive Materials and Bioinspired Technologies (FIT), Albert-Ludwigs-Universität Freiburg, Freiburg 79110, Germany
| | - Thomas Brandstetter
- Laboratory
for Chemistry & Physics of Interfaces, Department of Microsystems
Engineering (IMTEK), Albert-Ludwigs-Universität
Freiburg, Freiburg 79110, Germany
- Freiburg
Institute for Interactive Materials and Bioinspired Technologies (FIT), Albert-Ludwigs-Universität Freiburg, Freiburg 79110, Germany
| | - Markus Biesalski
- Macromolecular
Chemistry & Paper Chemistry, Technical
University of Darmstadt, Darmstadt 64287, Germany
| | - Jürgen Rühe
- Laboratory
for Chemistry & Physics of Interfaces, Department of Microsystems
Engineering (IMTEK), Albert-Ludwigs-Universität
Freiburg, Freiburg 79110, Germany
- Freiburg
Institute for Interactive Materials and Bioinspired Technologies (FIT), Albert-Ludwigs-Universität Freiburg, Freiburg 79110, Germany
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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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3
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Comparison of blocking reagents for antibody microarray-based immunoassays on glass and paper membrane substrates. Anal Bioanal Chem 2023; 415:1967-1977. [PMID: 36829042 DOI: 10.1007/s00216-023-04614-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 02/14/2023] [Accepted: 02/17/2023] [Indexed: 02/26/2023]
Abstract
Background noise due to nonspecific binding of biomolecules on the assay substrates is one of the most common challenges that limits the sensitivity of microarray-based immunoassays. Background signal intensity usually increases when complex biological fluids are used because they have a combination of molecules and vesicles that can adsorb onto substrate surfaces. Blocking strategies coupled with surface chemistries can reduce such nonspecific binding and improve assay sensitivity. In this paper, we conducted a systematic optimization of blocking strategies on a variety of commonly used substrates for protein measurement in complex biofluids. Four blocking strategies (BSA, non-fat milk, PEG, and a protein-free solution) coupled with four surface chemistries (3-glycidoxypropyltrimethoxysilane (GPS), poly-L-lysine (PLL), aminoalkylsilane (AAS), and nitrocellulose (NC)) were studied for their effect on background, microspot, and net signal intensities. We have also explored the effect that these blocking strategies have when proteins in complex samples (plasma, serum, cell culture media, and EV lysate) are measured. Irregular spot morphology could affect signal extraction using automated software. We found that the microspots with the best morphology were the ones printed on GPS glass surfaces for all immunoassays. On NC membrane, the protein-based blocking strategies yielded the highest net fluorescent intensity with the antigen contained in PBS, plasma, serum, and serum-free cell culture media. Differently, with EV lysate samples, Pierce™ protein-free blocker yielded the best net signal intensity on both GPS and NC surfaces. The choice of blocking strategies highly depends on the substrate. Moreover, the findings discovered in this study are not limited to microarray-based immunoassays but can provide insights for other assay formats.
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Zinggeler M, Schär S, Kurth F. Printed Antifouling Electrodes for Biosensing Applications. ACS APPLIED MATERIALS & INTERFACES 2022; 14:56578-56584. [PMID: 36513371 PMCID: PMC9802209 DOI: 10.1021/acsami.2c17557] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Accepted: 11/23/2022] [Indexed: 06/17/2023]
Abstract
Biosensors based on miniaturized, functional electrodes are of high potential for various biosensing applications, especially at the point-of-care setting among others. However, the sensor performance of such electrochemical devices is still strongly limited, especially due to surface fouling in complex sample fluids, such as blood serum. Electrode coatings based on conductive nanomaterials embedded in antifouling matrices offer a promising strategy to overcome this limitation. However, known composite coatings require long (typically >24 h) and complex fabrication processes, which pose a strong barrier for cost-effective mass manufacturing and successful commercialization. Here, we describe a novel polymer/carbon nanotube (CNT) composite coating that can be produced from an ink containing a photoreactive and antifouling copolymer as well as conductive CNTs using fast and highly scalable printing processes. Coatings were prepared on screen-printed electrodes and characterized using cyclic voltammetry (CV) and protein fouling experiments. The coatings offered an electroactive surface area (EASA) comparable to uncoated screen-printed electrodes and retained >90% of initial EASA after 1 h of exposure to concentrated bovine serum albumin solution, while uncoated electrodes decreased to <20% of initial EASA after the same treatment. Utilizing the universal crosslinking reaction of the polymer coating, antibodies against the inflammatory biomarker C-reactive protein (CRP) were photochemically immobilized on the electrodes. Functionalized electrodes were fabricated in <2 h and were successfully used to quantify nanogram-range concentrations of CRP spiked in undiluted human blood serum using a sandwich-immunoassay with electrochemical read-out, demonstrating the high potential of the platform for biosensing applications.
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Calidonio JM, Gomez-Marquez J, Hamad-Schifferli K. Nanomaterial and interface advances in immunoassay biosensors. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2022; 126:17804-17815. [PMID: 38957865 PMCID: PMC11218816 DOI: 10.1021/acs.jpcc.2c05008] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2024]
Abstract
Biosensors have been used for a remarkable array of applications, including infectious diseases, environmental monitoring, cancer diagnosis, food safety, and numerous others. In particular, the global COVID-19 pandemic has exposed a need for rapid tests, so the type of biosensor that has gained considerable interest recently are immunoassays, which are used for rapid diagnostics. The performance of paper-based lateral flow and dipstick immunoassays is influenced by the physical properties of the nanoparticles (NPs), NP-antibody conjugates, and paper substrate. Many materials innovations have enhanced diagnostics by increasing sensitivity or enabling unique readouts. However, negative side effects can arise at the interface between the biological sample and biomolecules and the NP or paper substrate, such as non-specific adsorption and protein denaturation. In this Perspective, we discuss the immunoassay components and highlight chemistry and materials innovations that can improve sensitivity. We also explore the range of bio-interface issues that can present challenges for immunoassays.
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Affiliation(s)
| | | | - Kimberly Hamad-Schifferli
- Department of Engineering, University of Massachusetts Boston, Boston, MA 02125
- School for the Environment, University of Massachusetts Boston, Boston, MA 02125
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The Bioanalytical and Biomedical Applications of Polymer Modified Substrates. Polymers (Basel) 2022; 14:polym14040826. [PMID: 35215740 PMCID: PMC8878960 DOI: 10.3390/polym14040826] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Revised: 02/14/2022] [Accepted: 02/17/2022] [Indexed: 01/11/2023] Open
Abstract
Polymers with different structures and morphology have been extensively used to construct functionalized surfaces for a wide range of applications because the physicochemical properties of polymers can be finely adjusted by their molecular weights, polydispersity and configurations, as well as the chemical structures and natures of monomers. In particular, the specific functions of polymers can be easily achieved at post-synthesis by the attachment of different kinds of active molecules such as recognition ligand, peptides, aptamers and antibodies. In this review, the recent advances in the bioanalytical and biomedical applications of polymer modified substrates were summarized with subsections on functionalization using branched polymers, polymer brushes and polymer hydrogels. The review focuses on their applications as biosensors with excellent analytical performance and/or as nonfouling surfaces with efficient antibacterial activity. Finally, we discuss the perspectives and future directions of polymer modified substrates in the development of biodevices for the diagnosis, treatment and prevention of diseases.
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7
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Iwasaki Y, Bunuasunthon S, Hoven VP. Protein patterning with antifouling polymer gel platforms generated using visible light irradiation. Chem Commun (Camb) 2021; 56:5472-5475. [PMID: 32356533 DOI: 10.1039/d0cc02092c] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Visible light-assisted protein patterning on a solid surface was performed with phosphorylcholine (PC) polymers bearing tyrosine residues. Because of the antifouling nature of PC polymers, protein immobilisation was regiospecifically controlled, thus enabling the microfabricated surfaces to be used as immunoassay platforms.
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Affiliation(s)
- Yasuhiko Iwasaki
- Department of Chemistry and Materials Engineering, Faculty of Chemistry, Materials and Bioengineering, Kansai University, 3-3-35 Yamate-cho, Suita-shi, Osaka 564-8680, Japan.
| | - Sukulya Bunuasunthon
- Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
| | - Voravee P Hoven
- Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand and Center of Excellence in Materials and Bio-interfaces, Chulalongkorn University, Bangkok 10330, Thailand
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Yuan L, Qu B, Chen J, Lv H, Yang X. Engineering modifiers bearing benzophenone with enhanced reactivity to construct surface microstructures. Polym Chem 2019. [DOI: 10.1039/c9py00764d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A novel strategy is proposed to construct a patterned surface with controllable thickness by designing the chain backbone of BP-capped modifiers.
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Affiliation(s)
- Liguang Yuan
- State Key Laboratory of Polymer Physics and Chemistry
- Changchun Institute of Applied Chemistry
- Chinese Academy of Sciences
- Changchun 130022
- P. R. China
| | - Baoliu Qu
- State Key Laboratory of Polymer Physics and Chemistry
- Changchun Institute of Applied Chemistry
- Chinese Academy of Sciences
- Changchun 130022
- P. R. China
| | - Jiayue Chen
- Wego Holding Company Limited
- Weihai 264210
- P.R. China
| | - Hongying Lv
- State Key Laboratory of Polymer Physics and Chemistry
- Changchun Institute of Applied Chemistry
- Chinese Academy of Sciences
- Changchun 130022
- P. R. China
| | - Xiaoniu Yang
- State Key Laboratory of Polymer Physics and Chemistry
- Changchun Institute of Applied Chemistry
- Chinese Academy of Sciences
- Changchun 130022
- P. R. China
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