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Lilly JL, Gottipati A, Cahall CF, Agoub M, Berron BJ. Comparison of eosin and fluorescein conjugates for the photoinitiation of cell-compatible polymer coatings. PLoS One 2018; 13:e0190880. [PMID: 29309430 PMCID: PMC5757926 DOI: 10.1371/journal.pone.0190880] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Accepted: 12/21/2017] [Indexed: 12/17/2022] Open
Abstract
Targeted photopolymerization is the basis for multiple diagnostic and cell encapsulation technologies. While eosin is used in conjunction with tertiary amines as a water-soluble photoinitiation system, eosin is not widely sold as a conjugate with antibodies and other targeting biomolecules. Here we evaluate the utility of fluorescein-labeled bioconjugates to photopolymerize targeted coatings on live cells. We show that although fluorescein conjugates absorb approximately 50% less light energy than eosin in matched photopolymerization experiments using a 530 nm LED lamp, appreciable polymer thicknesses can still be formed in cell compatible environments with fluorescein photosensitization. At low photoinitiator density, eosin allows more sensitive initiation of gelation. However at higher functionalization densities, the thickness of fluorescein polymer films begins to rival that of eosin. Commercial fluorescein-conjugated antibodies are also capable of generating conformal, protective coatings on mammalian cells with similar viability and encapsulation efficiency as eosin systems.
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Affiliation(s)
- Jacob L. Lilly
- Department of Chemical and Materials Engineering, University of Kentucky, Lexington, Kentucky, United States of America
| | - Anuhya Gottipati
- Department of Chemical and Materials Engineering, University of Kentucky, Lexington, Kentucky, United States of America
| | - Calvin F. Cahall
- Department of Chemical and Materials Engineering, University of Kentucky, Lexington, Kentucky, United States of America
| | - Mohamed Agoub
- Department of Chemical and Materials Engineering, University of Kentucky, Lexington, Kentucky, United States of America
| | - Brad J. Berron
- Department of Chemical and Materials Engineering, University of Kentucky, Lexington, Kentucky, United States of America
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2
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Zhuang D, Wen F, Cui Y, Tan T, Yang J. Chitosan/Ce(IV) redox polymerization-based amplification for detection of DNA point mutation. ACTA ACUST UNITED AC 2016. [DOI: 10.1002/pola.28050] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Dequan Zhuang
- State Key Laboratory of Chemical Resource, College of Life Science and Technology; Beijing University of Chemical Technology; Beijing 100029 China
| | - Fei Wen
- State Key Laboratory of Chemical Resource, College of Life Science and Technology; Beijing University of Chemical Technology; Beijing 100029 China
| | - Yanjun Cui
- State Key Laboratory of Chemical Resource, College of Life Science and Technology; Beijing University of Chemical Technology; Beijing 100029 China
| | - Tianwei Tan
- State Key Laboratory of Chemical Resource, College of Life Science and Technology; Beijing University of Chemical Technology; Beijing 100029 China
| | - Jing Yang
- State Key Laboratory of Chemical Resource, College of Life Science and Technology; Beijing University of Chemical Technology; Beijing 100029 China
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3
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Kaastrup K, Sikes HD. Using photo-initiated polymerization reactions to detect molecular recognition. Chem Soc Rev 2016; 45:532-45. [DOI: 10.1039/c5cs00205b] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Radical polymerization reactions initiated by light can be used to provide signal amplification in molecular binding assays.
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Affiliation(s)
| | - H. D. Sikes
- Department of Chemical Engineering
- USA
- Program in Polymers and Soft Matter
- Massachusetts Institute of Technology
- Cambridge
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4
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5
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Romero G, Lilly JJ, Abraham NS, Shin HY, Balasubramaniam V, Izumi T, Berron BJ. Protective Polymer Coatings for High-Throughput, High-Purity Cellular Isolation. ACS APPLIED MATERIALS & INTERFACES 2015; 7:17598-602. [PMID: 26244409 PMCID: PMC4544319 DOI: 10.1021/acsami.5b06298] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Cell-based therapies are emerging as the next frontier of medicine, offering a plausible path forward in the treatment of many devastating diseases. Critically, current methods for antigen positive cell sorting lack a high throughput method for delivering ultrahigh purity populations, prohibiting the application of some cell-based therapies to widespread diseases. Here we show the first use of targeted, protective polymer coatings on cells for the high speed enrichment of cells. Individual, antigen-positive cells are coated with a biocompatible hydrogel which protects the cells from a surfactant solution, while uncoated cells are immediately lysed. After lysis, the polymer coating is removed through orthogonal photochemistry, and the isolate has >50% yield of viable cells and these cells proliferate at rates comparable to control cells. Minority cell populations are enriched from erythrocyte-depleted blood to >99% purity, whereas the entire batch process requires 1 h and <$2000 in equipment. Batch scale-up is only contingent on irradiation area for the coating photopolymerization, as surfactant-based lysis can be easily achieved on any scale.
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Affiliation(s)
- Gabriela Romero
- Department of Chemical and Materials Engineering, Department of Biomedical Engineering, University of Kentucky, Lexington, Kentucky 40506, United States
| | - Jacob J. Lilly
- Department of Chemical and Materials Engineering, Department of Biomedical Engineering, University of Kentucky, Lexington, Kentucky 40506, United States
| | - Nathan S. Abraham
- Department
of Chemical Engineering, University of Massachusetts
Amherst, Amherst, Massachusetts 01003, United States
| | - Hainsworth Y. Shin
- Department of Chemical and Materials Engineering, Department of Biomedical Engineering, University of Kentucky, Lexington, Kentucky 40506, United States
| | - Vivek Balasubramaniam
- Department
of Pediatrics, University of Wisconsin, Madison, Wisconsin 53792, United States
| | - Tadahide Izumi
- Graduate
Center for Toxicology, University of Kentucky, Lexington, Kentucky 40536, United States
| | - Brad J. Berron
- Department of Chemical and Materials Engineering, Department of Biomedical Engineering, University of Kentucky, Lexington, Kentucky 40506, United States
- E-mail:
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6
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Lilly JL, Romero G, Xu W, Shin HY, Berron BJ. Characterization of molecular transport in ultrathin hydrogel coatings for cellular immunoprotection. Biomacromolecules 2015; 16:541-9. [PMID: 25592156 DOI: 10.1021/bm501594x] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
PEG hydrogels are routinely used in immunoprotection applications to hide foreign cells from a host immune system. Size-dependent transport is typically exploited in these systems to prevent access by macromolecular elements of the immune system while allowing the transport of low molecular weight nutrients. This work studies a nanoscale hydrogel coating for improved transport of beneficial low molecular weight materials across thicker hydrogel coatings while completely blocking transport of undesired larger molecular weight materials. Coatings composed of PEG diacrylate of molecular weight 575 and 3500 Da were studied by tracking the transport of fluorescently labeled dextrans across the coatings. The molecular weight of dextran at which the transport is blocked by these coatings are consistent with cutoff values in analogous bulk PEG materials. Additionally, the diffusion constants of 4 kDa dextrans across PEG 575 coatings (9.5 × 10(-10)-2.0 × 10(-9) cm(2)/s) was lower than across PEG 3500 coatings (5.9-9.8 × 10(-9) cm(2)/s), and these trends and magnitudes agree with bulk scale models. Overall, these nanoscale thin PEG diacrylate films offer the same size selective transport behavior of bulk PEG diacrylate materials, while the lower thickness translates directly to increased flux of beneficial low molecular weight materials.
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Affiliation(s)
- Jacob L Lilly
- Department of Chemical and Materials Engineering and ∥Department of Biomedical Engineering, University of Kentucky , Lexington, Kentucky 40506, United States
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7
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Lilly JL, Sheldon PR, Hoversten LJ, Romero G, Balasubramaniam V, Berron BJ. Interfacial polymerization for colorimetric labeling of protein expression in cells. PLoS One 2014; 9:e115630. [PMID: 25536421 PMCID: PMC4275217 DOI: 10.1371/journal.pone.0115630] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2014] [Accepted: 11/26/2014] [Indexed: 11/18/2022] Open
Abstract
Determining the location of rare proteins in cells typically requires the use of on-sample amplification. Antibody based recognition and enzymatic amplification is used to produce large amounts of visible label at the site of protein expression, but these techniques suffer from the presence of nonspecific reactivity in the biological sample and from poor spatial control over the label. Polymerization based amplification is a recently developed alternative means of creating an on-sample amplification for fluorescence applications, while not suffering from endogenous labels or loss of signal localization. This manuscript builds upon polymerization based amplification by developing a stable, archivable, and colorimetric mode of amplification termed Polymer Dye Labeling. The basic concept involves an interfacial polymer grown at the site of protein expression and subsequent staining of this polymer with an appropriate dye. The dyes Evans Blue and eosin were initially investigated for colorimetric response in a microarray setting, where both specifically stained polymer films on glass. The process was translated to the staining of protein expression in human dermal fibroblast cells, and Polymer Dye Labeling was specific to regions consistent with desired protein expression. The labeling is stable for over 200 days in ambient conditions and is also compatible with modern mounting medium.
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Affiliation(s)
- Jacob L. Lilly
- Department of Chemical and Materials Engineering, University of Kentucky, Lexington, Kentucky, United States of America
| | - Phillip R. Sheldon
- Department of Chemical and Materials Engineering, University of Kentucky, Lexington, Kentucky, United States of America
| | - Liv J. Hoversten
- Department of Pediatrics, University of Colorado, Denver, Colorado, United States of America
| | - Gabriela Romero
- Department of Chemical and Materials Engineering, University of Kentucky, Lexington, Kentucky, United States of America
| | - Vivek Balasubramaniam
- Department of Pediatrics, University of Colorado, Denver, Colorado, United States of America
| | - Brad J. Berron
- Department of Chemical and Materials Engineering, University of Kentucky, Lexington, Kentucky, United States of America
- * E-mail:
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8
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Zhuang D, Shen H, Liu G, Yu C, Yang J. A combining signal amplification of atom transfer radical polymerization and redox polymerization for visual biomolecules detection. ACTA ACUST UNITED AC 2014. [DOI: 10.1002/pola.27303] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Dequan Zhuang
- State Key Laboratory of Chemical Resource, College of Life Science and Technology; Beijing University of Chemical Technology; Beijing 100029 China
| | - Heyun Shen
- State Key Laboratory of Chemical Resource, College of Life Science and Technology; Beijing University of Chemical Technology; Beijing 100029 China
| | - Guodong Liu
- State Key Laboratory of Chemical Resource, College of Life Science and Technology; Beijing University of Chemical Technology; Beijing 100029 China
| | - Changyuan Yu
- State Key Laboratory of Chemical Resource, College of Life Science and Technology; Beijing University of Chemical Technology; Beijing 100029 China
| | - Jing Yang
- State Key Laboratory of Chemical Resource, College of Life Science and Technology; Beijing University of Chemical Technology; Beijing 100029 China
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9
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Kaastrup K, Chan L, Sikes HD. Impact of Dissociation Constant on the Detection Sensitivity of Polymerization-Based Signal Amplification Reactions. Anal Chem 2013; 85:8055-60. [DOI: 10.1021/ac4018988] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Kaja Kaastrup
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139,
United States
| | - Leslie Chan
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139,
United States
| | - Hadley D. Sikes
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139,
United States
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10
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Yuan L, Wei W, Liu S. Label-free electrochemical immunosensors based on surface-initiated atom radical polymerization. Biosens Bioelectron 2012; 38:79-85. [DOI: 10.1016/j.bios.2012.05.007] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2012] [Revised: 05/05/2012] [Accepted: 05/07/2012] [Indexed: 11/30/2022]
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11
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Avens HJ, Berron BJ, May AM, Voigt KR, Seedorf GJ, Balasubramaniam V, Bowman CN. Sensitive immunofluorescent staining of cells via generation of fluorescent nanoscale polymer films in response to biorecognition. J Histochem Cytochem 2011; 59:76-87. [PMID: 21339175 DOI: 10.1369/jhc.2010.955948] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Immunofluorescent staining is central to nearly all cell-based research, yet only a few fluorescent signal amplification approaches for cell staining exist, each with distinct limitations. Here, the authors present a novel, fluorescent polymerization-based amplification (FPBA) method that is shown to enable similar signal intensities as the highly sensitive, enzyme-based tyramide signal amplification (TSA) approach. Being non-enzymatic, FPBA is not expected to suffer from nonspecific staining of endogenous enzymes, as occurs with enzyme-based approaches. FPBA employs probes labeled with photopolymerization initiators, which lead to the controlled formation of fluorescent polymer films only at targeted biorecognition sites. Nuclear pore complex proteins (NPCs; in membranes), vimentin (in filaments), and von Willebrand factor (in granules) were all successfully immunostained by FPBA. Also, FPBA was demonstrated to be capable of multicolor immunostaining of multiple antigens. To assess relative sensitivity, decreasing concentrations of anti-NPC antibody were used, indicating that both FPBA and TSA stained NPC down to a 1:100,000 dilution. Nonspecific, cytoplasmic signal resulting from NPC staining was found to be reduced up to 5.5-fold in FPBA as compared to TSA, demonstrating better signal localization with FPBA. FPBA's unique approach affords a combination of preferred attributes, including high sensitivity and specificity not otherwise available with current techniques.
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Affiliation(s)
- Heather J Avens
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, CO 80309, USA
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12
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Berron BJ, Johnson LM, Ba X, McCall JD, Alvey NJ, Anseth KS, Bowman CN. Glucose oxidase-mediated polymerization as a platform for dual-mode signal amplification and biodetection. Biotechnol Bioeng 2011; 108:1521-8. [PMID: 21337335 PMCID: PMC3098304 DOI: 10.1002/bit.23101] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2010] [Revised: 01/31/2011] [Accepted: 02/07/2011] [Indexed: 11/22/2022]
Abstract
We report the first use of a polymerization-based ELISA substrate solution employing enzymatically mediated radical polymerization as a dual-mode amplification strategy. Enzymes are selectively coupled to surfaces to generate radicals that subsequently lead to polymerization-based amplification (PBA) and biodetection. Sensitivity and amplification of the polymerization-based detection system were optimized in a microwell strip format using a biotinylated microwell surface with a glucose oxidase (GOx)–avidin conjugate. The immobilized GOx is used to initiate polymerization, enabling the detection of the biorecognition event visually or through the use of a plate reader. Assay response is compared to that of an enzymatic substrate utilizing nitroblue tetrazolium in a simplified assay using biotinylated wells. The polymerization substrate exhibits equivalent sensitivity (2 µg/mL of GOx-avidin) and over three times greater signal amplification than this traditional enzymatic substrate since each radical that is enzymatically generated leads to a large number of polymerization events. Enzyme-mediated polymerization proceeds in an ambient atmosphere without the need for external energy sources, which is an improvement upon previous PBA platforms. Substrate formulations are highly sensitive to both glucose and iron concentrations at the lowest enzyme concentrations. Increases in amplification time correspond to higher assay sensitivities with no increase in non-specific signal. Finally, the polymerization substrate generated a signal to noise ratio of 14 at the detection limit (156 ng/mL) in an assay of transforming growth factor-beta. Biotechnol. Bioeng. 2011; 108:1521–1528. © 2011 Wiley Periodicals, Inc.
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Affiliation(s)
- Brad J Berron
- Department of Chemical and Biological Engineering, ECCH 111, UCB 424, University of Colorado, Boulder, Colorado 80309-0424, USA
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13
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Yuan L, Wu Y, Shi H, Liu S. Surface-Initiated Atom-Transfer Radical Polymerization of 4-Acetoxystyrene for Immunosensing. Chemistry 2010; 17:976-83. [DOI: 10.1002/chem.201001271] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Indexed: 11/09/2022]
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14
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Shenoy R, Bowman CN. Mechanism and Implementation of Oxygen Inhibition Suppression in Photopolymerizations by Competitive Photoactivation of a Singlet Oxygen Sensitizer. Macromolecules 2010. [DOI: 10.1021/ma1012682] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Raveesh Shenoy
- Department of Chemical Engineering, University of Colorado, Boulder, Colorado 80309-0424
| | - Christopher N. Bowman
- Department of Chemical Engineering, University of Colorado, Boulder, Colorado 80309-0424
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15
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Horgan AM, Moore JD, Noble JE, Worsley GJ. Polymer- and colloid-mediated bioassays, sensors and diagnostics. Trends Biotechnol 2010; 28:485-94. [DOI: 10.1016/j.tibtech.2010.06.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Revised: 06/18/2010] [Accepted: 06/27/2010] [Indexed: 11/28/2022]
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16
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Johnson LM, DeForest CA, Pendurti A, Anseth KS, Bowman CN. Formation of three-dimensional hydrogel multilayers using enzyme-mediated redox chain initiation. ACS APPLIED MATERIALS & INTERFACES 2010; 2:1963-72. [PMID: 20586415 PMCID: PMC2935794 DOI: 10.1021/am100275n] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Enzyme-mediated redox chain initiation involving glucose oxidase (GOX) was employed in an iterative solution dip-coating technique to polymerize multiple, three-dimensional hydrogel layers using mild aqueous conditions at ambient temperature and oxygen levels. To the best of our knowledge, sequential enzyme-mediated dip-coating resulting in an interfacial radical chain polymerization and subsequent formation of three-dimensional hydrogel layers has not been previously explored. Conformal, micrometer-scale, uniform poly(ethylene glycol) (PEG)-based hydrogel layers were polymerized within seconds and remained securely associated after incubation in water for 16 weeks. Incorporation of either small molecules (i.e., rhodamine-B acrylate, fluorescein acrylate) or fluorescent nanoparticles into crosslinked hydrogel layers during the polymerization reaction was also achieved. The encapsulation of 0.2 microm-diameter nanoparticles into hydrogels during polymerization of a 2-hydroxyethyl acrylate (HEA)/PEG(575) diacrylate monomer formulation, using the GOX-mediated initiation, resulted in minimal effects on polymerization kinetics, with final acrylate conversions of 95% (+/- 1%) achieved within minutes. The temporal control and spatial localization afforded by this interfacial redox approach resulted in the polymerization of uniform secondary layers ranging between 150 (+/- 10) microm and 650 (+/- 10) microm for 15 and 120 s immersion times, respectively. Moreover, increasing the PEG(575)-fraction within the initial hydrogel substrate from 10 to 50% decreased the subsequent layer thicknesses from 690 (+/- 30) microm to 490 (+/- 10) microm because of lowered glucose concentration at the hydrogel interface. The ability to sequentially combine differing initiation mechanisms with this coating approach was achieved by using GOX-mediated interfacial polymerization on hydrogel substrates initially photopolymerized in the presence of glucose. The strict control of layer thicknesses combined with the rapid, water-soluble, and mild polymerization will readily benefit applications requiring formation of stratified, complex, and three-dimensional polymer structures.
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Affiliation(s)
- Leah M. Johnson
- Department of Chemical and Biological Engineering, ECCH 111 CB 424, University of Colorado, Boulder, Colorado 80309
| | - Cole A. DeForest
- Department of Chemical and Biological Engineering, ECCH 111 CB 424, University of Colorado, Boulder, Colorado 80309
| | - Aishwarya Pendurti
- Department of Chemical and Biological Engineering, ECCH 111 CB 424, University of Colorado, Boulder, Colorado 80309
| | - Kristi S. Anseth
- Department of Chemical and Biological Engineering, ECCH 111 CB 424, University of Colorado, Boulder, Colorado 80309
| | - Christopher N. Bowman
- Department of Chemical and Biological Engineering, ECCH 111 CB 424, University of Colorado, Boulder, Colorado 80309
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17
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Avens HJ, Bowman CN. Development of fluorescent polymerization-based signal amplification for sensitive and non-enzymatic biodetection in antibody microarrays. Acta Biomater 2010; 6:83-9. [PMID: 19508906 DOI: 10.1016/j.actbio.2009.06.008] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2009] [Revised: 05/01/2009] [Accepted: 06/02/2009] [Indexed: 10/20/2022]
Abstract
Antibody microarrays are a critical tool for proteomics, requiring broad, highly sensitive detection of numerous low abundance biomarkers. Fluorescent polymerization-based amplification (FPBA) is presented as a novel, non-enzymatic signal amplification method that takes advantage of the chain-reaction nature of radical polymerization to achieve a highly amplified fluorescent response. A streptavidin-eosin conjugate localizes eosin photoinitiators for polymerization on the chip where biotinylated target protein is bound. The chip is contacted with acrylamide as a monomer, N-methyldiethanolamine as a coinitiator and yellow/green fluorescent nanoparticles (NPs) which, upon initiation, combine to form a macroscopically visible and highly fluorescent film. The rapid polymerization kinetics and the presence of cross-linker favor entrapment of the fluorescent NPs in the polymer, enabling highly sensitive fluorescent biodetection. This method is demonstrated as being appropriate for antibody microarrays and is compared to detection approaches which utilize streptavidin-fluorescein isothiocyanate (SA-FITC) and streptavidin-labeled yellow/green NPs (SA-NPs). It is found that FPBA is able to detect 0.16 + or - 0.01 biotin-antibody microm(-2) (or 40 zmol surface-bound target molecules), while SA-FITC has a limit of detection of 31 + or - 1 biotin-antibody microm(-2) and SA-NPs fail to achieve any significant signal under the conditions evaluated here. Further, FPBA in conjunction with fluorescent stereomicroscopy yields equal or better sensitivity compared to fluorescent detection of SA-eosin using a much more costly microarray scanner. By facilitating highly sensitive detection, FPBA is expected to enable detection of low abundance antigens and also make possible a transition towards less expensive fluorescence detection instrumentation.
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18
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Avens HJ, Bowman CN. Mechanism of Cyclic Dye Regeneration During Eosin-Sensitized Photoinitiation in the Presence of Polymerization Inhibitors. ACTA ACUST UNITED AC 2009; 47:6083-6094. [PMID: 20098667 DOI: 10.1002/pola.23649] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A visible light photoinitiator, eosin, in combination with a tertiary amine coinitiator is found to initiate polymerization despite the presence of at least 1000-fold excess dissolved oxygen which functions as an inhibitor of radical polymerizations. Additionally, 0.4 µM eosin is able to overcome 100-fold excess (40 µM) 2,2,6,6-Tetramethyl-1-piperidinyloxy (TEMPO) inhibitor, initiating polymerization after only a 2 minute inhibition period. In contrast, 40 µM Irgacure-2959, a standard cleavage-type initiator, is unable to overcome even an equivalent amount of inhibitor (40 µM TEMPO). Through additional comparisons of these two initiation systems, a reaction mechanism is developed which is consistent with the kinetic data and provides an explanation for eosin's relative insensitivity to oxygen, TEMPO and other inhibitors. A cyclic mechanism is proposed in which semi-reduced eosin radicals react by disproportionation with radical inhibitors and radical intermediates in the inhibition process to regenerate eosin and effectively consume inhibitor. In behavior similar to that of eosin, rose bengal, fluorescein, and riboflavin are also found to initiate polymerization despite the presence of excess TEMPO, indicating that cyclic regeneration likely enhances the photoinitiation kinetics of many dye photosensitizers. Selection of such dye initiation systems constitutes a valuable strategy for alleviating inhibitory effects in radical polymerizations.
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Affiliation(s)
- Heather J Avens
- University of Colorado at Boulder, Department of Chemical and Biological Engineering, UCB 424, Boulder, CO 80309
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19
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Hansen RR, Johnson LM, Bowman CN. Visual, base-specific detection of nucleic acid hybridization using polymerization-based amplification. Anal Biochem 2009; 386:285-7. [DOI: 10.1016/j.ab.2008.12.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2008] [Revised: 12/05/2008] [Accepted: 12/09/2008] [Indexed: 11/30/2022]
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20
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Johnson LM, Avens HJ, Hansen RR, Sewell HL, Bowman CN. Characterization of the Assaying Methods in Polymerization-Based Amplification of Surface Biomarkers. Aust J Chem 2009. [DOI: 10.1071/ch09095] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Polymerization-based amplification (PBA), which combines bio-recognition events with polymerization reactions on surfaces, provides visual, sensitive, and cost-effective detection of biological interactions, particularly at extremely low levels of the targeted biological moiety. This study characterizes assay parameters that enhance the utility of PBA to detect nucleic acid and protein biomarkers. Here, we successfully employ PBA on surfaces that contain uniform, high density, immobilized capture molecules, including three-dimensional nitrocellulose-coated substrates. Optimized assay and polymerization conditions are used to characterize the dynamic polymer film heights on glass substrates that result from solutions of KRAS proto-oncogene biomarker targets at concentrations between 5 nM and 500 pM. Differing aqueous monomer formulations are utilized to produce 20 nm films at the 500 pM DNA detection limit.
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21
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Bowman CN, Kloxin CJ. Toward an enhanced understanding and implementation of photopolymerization reactions. AIChE J 2008. [DOI: 10.1002/aic.11678] [Citation(s) in RCA: 193] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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22
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Polymerization Behavior and Polymer Properties of Eosin-Mediated Surface Modification Reactions. POLYMER 2008; 49:4762-4768. [PMID: 19838291 DOI: 10.1016/j.polymer.2008.08.054] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Surface modification by surface-mediated polymerization necessitates control of the grafted polymer film thicknesses to achieve the desired property changes. Here, a microarray format is used to assess a range of reaction conditions and formulations rapidly in regards to the film thicknesses achieved and the polymerization behavior. Monomer formulations initiated by eosin conjugates with varying concentrations of poly(ethylene glycol) diacrylate (PEGDA), N-methyldiethanolamine (MDEA), and 1-vinyl-2-pyrrolidone (VP) were evaluated. Acrylamide with MDEA or ascorbic acid as a coinitiator was also investigated. The best formulation was found to be 40 wt% acrylamide with MDEA which yielded four to eight fold thicker films (maximum polymer thickness increased from 180 nm to 1420 nm) and generated visible films from 5-fold lower eosin surface densities (2.8 vs. 14 eosins/µm(2)) compared to a corresponding PEGDA formulation. Using a microarray format to assess multiple initiator surface densities enabled facile identification of a monomer formulation that yields the desired polymer properties and polymerization behavior across the requisite range of initiator surface densities.
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