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Tai, Feng-i
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Publications (8 of 8) Show all publications
Tai, F.-i., Sterner, O., Andersson, O., Ekblad, T. & Ederth, T. (2019). Interaction Forces on Polyampholytic Hydrogel Gradient Surfaces. ACS Omega, 4(3), 5670-5681
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2019 (English)In: ACS Omega, ISSN 2470-1343, Vol. 4, no 3, p. 5670-5681Article in journal (Refereed) Published
Abstract [en]

Rational design and informed development of nontoxic antifouling coatings requires a thorough understanding of the interactions between surfaces and fouling species. With more complex antifouling materials, such as composites or zwitterionic polymers, there follows also a need for better characterization of the materials as such. To further the understanding of the antifouling properties of charge-balanced polymers, we explore the properties of layered polyelectrolytes and their interactions with charged surfaces. These polymers were prepared via self-initiated photografting and photopolymerization (SIPGP); on top of a uniform bottom layer of anionic poly(methacrylic acid) (PMAA), a cationic poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) thickness gradient was formed. Infrared microscopy and imaging spectroscopic ellipsometry were used to characterize chemical composition and swelling of the combined layer. Direct force measurements by colloidal probe atomic force microscopy were performed to investigate the forces between the polymer gradients and charged probes. The swelling of PMAA and PDMAEMA are very different, with steric and electrostatic forces varying in a nontrivial manner along the gradient. The gradients can be tuned to form a protein-resistant charge-neutral region, and we demonstrate that this region, where both electrostatic and steric forces are small, is highly compressed and the origin of the protein resistance of this region is most likely an effect of strong hydration of charged residues at the surface, rather than swelling or bulk hydration of the polymer. In the highly swollen regions far from charge-neutrality, steric forces dominate the interactions between the probe and the polymer. In these regions, the SIPGP polymer has qualitative similarities with brushes, but we were unable to quantitatively describe the polymer as a brush, supporting previous data suggesting that these polymers are cross-linked.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2019
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:liu:diva-156495 (URN)10.1021/acsomega.9b00339 (DOI)000462921900124 ()31459721 (PubMedID)2-s2.0-85063358089 (Scopus ID)
Note

Funding agencies: European Commissions Sixth Framework Program Integrated Project AMBIO (Advanced Nanostructured Surfaces for the Control of Biofouling) [NMP-CT-2005-011827]; European Communitys Seventh Framework Program [237997]; Swedish Government Strategic Research Area

Available from: 2019-04-24 Created: 2019-04-24 Last updated: 2019-09-09Bibliographically approved
Tai, F.-I. (2019). Surface characterization and manipulation of polyampholytic hydrogel coatings. (Doctoral dissertation). Linköping: Linköping University Electronic Press
Open this publication in new window or tab >>Surface characterization and manipulation of polyampholytic hydrogel coatings
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis is dedicated to building up fundamental knowledge about polyampholytic hydrogels, which are developed in our group for anti-fouling purposes. Charge-balanced polymers, where positive and negative charges balance each other, have emerged as interesting candidates for many applications in materials science. We have prepared charge-balanced materials by forming thickness gradients of oppositely charged polyelectrolytes, and use these as model systems for a systematic investigation of the materials and their responses to environmental changes. These hydrogel gradients were sequentially grafted from substrates via surface-initiated photografting and photopolymerization (SIPGP) of cationic and anionic polyelectrolytes. At some thickness ratios, these form a charge-balanced system where the net surface charge is zero, and with certain similarity to zwitterionic systems. The surface charge of the hydrogels is the principal parameter regulating non-specific protein adsorption, and among other things, we demonstrate that the position of the fouling-resistant charge-neutral region can be manipulated upon pH changes. The chemical compositions of the hydrogel gradients were characterized by microscopic infrared spectroscopy. Optical analysis by spectroscopic ellipsometry and imaging surface plasmon resonance were used to monitor the swelling of the hydrogel films, and protein adsorption onto these in real-time. Surface forces, i.e. the interactions with the hydrogels from an intermolecular perspective, which are related mainly to electrostatic and steric forces, were probed by direct force measurement using atomic force microscopy. Force curves were used to determine the surface charge distribution over the hydrogels, and to indicate the correlation between surface charge and protein adsorption. In the later work, hydrogel gradients were patterned as arrayed spots. Their thicknesses and surface roughness provide further information about the polymer structure and provides a basis for relating ellipsometric swelling profiles to thicknesses as obtained by atomic force microscopy. Finally, it is demonstrated how charged hydrogel films can be used as spacers to tune the optimum distance between silver nanoparticles and fluorophores for metal-enhanced fluorescence (MEF). The aim of this work is to understand polyampholytic hydrogels from various perspectives: surface charges and their distribution, the polymer structure, and surface interactions. The knowledge and experience obtained contribute to the general understanding of zwitterionic materials, and to the development of anti-fouling coatings, optical sensing platforms and other applications of charge-balanced hydrogels.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2019. p. 74
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1987
Keywords
Hydrogels, antifouling, charge-balanced material, polyampholytes, force measurements, polymer swelling, protein adsorption, patterning, plasmonics
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:liu:diva-156496 (URN)10.3384/diss.diva-156496 (DOI)9789176850831 (ISBN)
Public defence
2019-05-17, Planck, Fysikhuset, Campus Valla, Linköping, 10:00 (English)
Opponent
Supervisors
Available from: 2019-04-24 Created: 2019-04-24 Last updated: 2019-04-29Bibliographically approved
Tai, F.-I., Sterner, O., Andersson, O., Ekblad, T. & Ederth, T. (2015). pH-control of the protein resistance of hydrogel gradient films. In: : . Paper presented at 79th Prague Meeting on Macromolecules, Prague, Czech, 28 June - 2 July 2015.
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2015 (English)Conference paper, Poster (with or without abstract) (Other academic)
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-122697 (URN)
Conference
79th Prague Meeting on Macromolecules, Prague, Czech, 28 June - 2 July 2015
Available from: 2015-11-16 Created: 2015-11-16 Last updated: 2018-09-26Bibliographically approved
Tai, F.-i., Sterner, O., Andersson, O., Ekblad, T. & Ederth, T. (2014). pH-control of the protein resistance of thin hydrogel gradient films. Soft Matter, 10(32), 5955-5964
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2014 (English)In: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, Vol. 10, no 32, p. 5955-5964Article in journal (Refereed) Published
Abstract [en]

We report on the preparation and characterization of thin polyampholytic hydrogel gradient films permitting pH-controlled protein resistance via the regulation of surface charges. The hydrogel gradients are composed of cationic poly(2-aminoethyl methacrylate hydrochloride) (PAEMA), and anionic poly(2-carboxyethyl acrylate) (PCEA) layers, which are fabricated by self-initiated photografting and photopolymerization (SIPGP). Using a two-step UV exposure procedure, a polymer thickness gradient of one component is formed on top of a uniform layer of the oppositely charged polymer. The swelling of the gradient films in water and buffers at different pH were characterized by imaging spectroscopic ellipsometry. The surface charge distribution and steric interactions with the hydrogel gradients were recorded by direct force measurement with colloidal-probe atomic force microscopy. We demonstrate that formation of a charged polymer thickness gradient on top of a uniform layer of opposite charge can result in a region of charge-neutrality. This charge-neutral region is highly resistant to non-specific adsorption of proteins, and its location along the gradient can be controlled via the pH of the surrounding buffer. The pH-controlled protein adsorption and desorption was monitored in real-time by imaging surface plasmon resonance, while the corresponding redistribution of surface charge was confirmed by direct force measurements.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2014
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-110502 (URN)10.1039/c4sm00833b (DOI)000340474400011 ()24987939 (PubMedID)
Note

Funding Agencies|European Commission [NMP-CT-2005-011827]; European Community [237997]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009-00971]

Available from: 2014-09-12 Created: 2014-09-12 Last updated: 2019-04-24
Hamedi, M., Wigenius, J., Tai, F.-i., Björk, P. & Aili, D. (2010). Polypeptide-guided assembly of conducting polymer nanocomposites. NANOSCALE, 2(10), 2058-2061
Open this publication in new window or tab >>Polypeptide-guided assembly of conducting polymer nanocomposites
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2010 (English)In: NANOSCALE, ISSN 2040-3364, Vol. 2, no 10, p. 2058-2061Article in journal (Refereed) Published
Abstract [en]

A strategy for fabrication of electroactive nanocomposites with nanoscale organization, based on self-assembly, is reported. Gold nanoparticles are assembled by a polypeptide folding-dependent bridging. The polypeptides are further utilized to recruit and associate with a water soluble conducting polymer. The polymer is homogenously incorporated into the nanocomposite, forming conducting pathways which make the composite material highly conducting.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2010
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-61181 (URN)10.1039/c0nr00299b (DOI)000282686200019 ()
Note
Original Publication: Mahiar Hamedi, Jens Wigenius, Feng-i Tai, Per Björk and Daniel Aili, Polypeptide-guided assembly of conducting polymer nanocomposites, 2010, NANOSCALE, (2), 10, 2058-2061. http://dx.doi.org/10.1039/c0nr00299b Copyright: Royal Society of Chemistry http://www.rsc.org/ Available from: 2010-11-05 Created: 2010-11-05 Last updated: 2014-10-08Bibliographically approved
Hamedi, M., Wigenius, J., Tai, F.-I., Björk, P. & Aili, D. (2010). Synthetic Polypeptides as Scaffolds for Supramolecular Assembly of Conducting Polymer Nanocomposites.
Open this publication in new window or tab >>Synthetic Polypeptides as Scaffolds for Supramolecular Assembly of Conducting Polymer Nanocomposites
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2010 (English)Manuscript (preprint) (Other academic)
Abstract [en]

The development of nanoelectronics has resulted in enormous advancements in fabrication techniques that have enabled massproduction of CMOS circuits with feature sizes below 45nm. There is a large interest in new methods to further push the size limits, lower the production costs and to facilitate the design of more advanced three-dimensional structures beyond today’s 2.5 dimensional architectures. Self-assembly is probably the most important scheme in this development and is currently applied to many different areas and classes of nanoelectronics. Self-assembly enables fabrication of structures well below 10 nm in feature size and allows for incorporation of novel nanomaterials, such as metallic and semiconducting nanoparticles with many interesting optical and electrical properties. The controlled self-assembly of electro-active nanocomposites is of great interest for the development of novel functional materials including biosensors, electrochromic/plasmonic hybrid devices, and polymer/nanoparticle-based memories.

Keywords
Conducting Polymers, Organic Electronics, Conducting Nanowires, Self- Assembly, Supramolecular Materials
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-54901 (URN)
Available from: 2010-04-20 Created: 2010-04-20 Last updated: 2010-04-20
Ekblad, T., Andersson, O., Tai, F.-i., Ederth, T. & Liedberg , B. (2009). Lateral Control of Protein Adsorption on Charged Polymer Gradients. Langmuir, 25(6), 3755-3762
Open this publication in new window or tab >>Lateral Control of Protein Adsorption on Charged Polymer Gradients
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2009 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 25, no 6, p. 3755-3762Article in journal (Refereed) Published
Abstract [en]

This work describes the fabrication, characterization, and protein adsorption behavior of charged polymer gradients. The thin gradient films were fabricated by a two-step technique using UV-initiated free-radical polymerization in a reactor with a moving shutter. A homogeneous layer of cationic poly(2-aminoethyl methacrylate hydrochloride) was first formed, followed by a layer of oppositely charged poly(2-carboxyethyl acrylate) with a continuously increasing thickness. Adsorption from protein solutions as well as human blood plasma was investigated by imaging surface plasmon resonance and infrared microscopy. The results showed excessive protein adsorption in the areas where one of the polymers dominated the composition, while there was a clear minimum at an intermediate position of the gradient. The charge of the surface was estimated by direct force measurements and found to correlate well with the protein adsorption, showing the lowest net charge in the same area as the protein adsorption minimum. We therefore hypothesize that a combination of the charged polymers, in the right proportions, can result in a protein-resistant surface due to balanced charges.

National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-17501 (URN)10.1021/la803443d (DOI)
Available from: 2009-03-27 Created: 2009-03-27 Last updated: 2019-04-24
Aili, D., Tai, F.-I., Enander, K., Baltzer, L. & Liedberg, B. (2008). Self-Assembly of Fibers and Nanorings from Disulfide-Linked Helix–Loop–Helix Polypeptides. Angewandte Chemie International Edition, 47(30), 5554-5556
Open this publication in new window or tab >>Self-Assembly of Fibers and Nanorings from Disulfide-Linked Helix–Loop–Helix Polypeptides
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2008 (English)In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 47, no 30, p. 5554-5556Article in journal (Refereed) Published
Place, publisher, year, edition, pages
Wiley InterScience, 2008
Keywords
fibers, helical structures, nanostructures, polypeptides, self-assembly
National Category
Other Basic Medicine
Identifiers
urn:nbn:se:liu:diva-15120 (URN)10.1002/anie.200801155 (DOI)
Available from: 2008-10-16 Created: 2008-10-16 Last updated: 2018-01-12Bibliographically approved
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