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Signal Enhancement by Dynamic Polymers in Quartz Crystal Microbalance Applications
KTH, School of Chemical Science and Engineering (CHE), Chemistry. (Ramström)
2009 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

 This licentiate thesis presents studies of signal enhancement by dynamic polymers in quartz crystal microbalance (QCM) applications. The aim of the study has been to determine the potential for the use of polymers on QCM sensors for signal enhancement in molecular interaction studies. A method for synthesis of polymer sensor surfaces on QCM substrates was developed based on an iniferter photo polymerization technique. Polymerized poly(acrylic acid) and poly(acryl amide) surfaces were extensively characterized with electron spectroscopy for chemical analysis (ESCA), infrared reflection absorption spectroscopy (IRAS) and atomic force microscopy (AFM). The QCM response dynamics of these surfaces to pH changes was studied and the carboxyl containing surfaces exhibited large, reversible and highly reproducible frequency shifts due to expansion of deprotonated polymer chains. Surface acid dissociation constants (pKa) were determined for poly(acrylic acid) surfaces, carboxymethyldextran surfaces and self-assembled monolayer carboxyl surfaces by means of pH titration in QCM flow-through instrumentation. Surface pKa data was consistent with available literature data. The sensitivity enhancement for molecular interaction studies was investigated for poly(acrylic acid) coated QCM sensors with a model system consisting of immobilized biotin and an anti-biotin Fab fragment. Binding responses of antibiotin Fab to immobilized biotin was revealed to be 11 times higher than the corresponding results for a carboxylated SAM surface.

 

Place, publisher, year, edition, pages
Stockholm: KTH , 2009. , 41 p.
Series
Trita-CHE-Report, ISSN 1654-1081 ; 2009:17
Keyword [en]
Signal enhancement, QCM, polyelectrolytes, hydrogel, iniferter, photopolymerization, dynamic polymers
National Category
Chemical Sciences
Identifiers
URN: urn:nbn:se:kth:diva-10305ISBN: 978-91-7415-307-1 (print)OAI: oai:DiVA.org:kth-10305DiVA: diva2:214563
Presentation
2009-05-27, E3, Osquars backe 14, Stockholm, 10:00 (English)
Opponent
Supervisors
Available from: 2009-05-07 Created: 2009-05-06 Last updated: 2010-10-15Bibliographically approved
List of papers
1. Surface-confined photopolymerization of pH-responsive acrylamide/acrylate brushes on polymer thin films
Open this publication in new window or tab >>Surface-confined photopolymerization of pH-responsive acrylamide/acrylate brushes on polymer thin films
Show others...
2008 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 24, no 14, 7559-7564 p.Article in journal (Refereed) Published
Abstract [en]

Dynamic acrylamide/acrylate polymeric brushes were synthesized at gold-plated quartz crystal surfaces. The crystals were initially coated with polystyrene-type thin films, derivatized with photolabile iniferter groups, and subsequently subjected to photoinitiated polymerization in acrylamide/acrylate monomer feeds. This surface-confined polymerization method enabled direct photocontrol over the polymerization, as followed by increased frequency responses of the crystal oscillations in a quartz crystal microbalance (QCM). The produced polymer layers were also found to be highly sensitive to external acid/base stimuli. Large oscillation frequency shifts were detected when the brushes were exposed to buffer solutions of different pH. The dynamic behavior of the resulting polymeric brushes was evaluated, and the extent of expansion and contraction of the films was monitored by the QCM setup in situ in real time. The resulting responses were rapid, and the effects were fully reversible. Low pH resulted in full contractions of the films, whereas higher pH yielded maximal expansion in order to minimize repulsion around the charged acrylate centers. The surfaces also proved to be very robust because the responsiveness was reproducible over many cycles of repeated expansion and contraction. Using ellipsometry, copolymer layers were estimated to be similar to 220 nm in a collapsed state and similar to 340 nm in the expanded state, effectively increasing the thickness of the film by 55%.

Keyword
Bioelectric phenomena, Brushes, Chemical reactions, Crystallography, Frequency response, Gold, Molecular beam epitaxy, Monomers, Oxide minerals, Photopolymerization, Polyethylenes, Polymerization, Polymers, Powders, Quartz, Quartz crystal microbalances, Shrinkage, Thick films, Thin films
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-17676 (URN)10.1021/la800700h (DOI)000257468300072 ()2-s2.0-47949088757 (Scopus ID)
Note
QC 20100525Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2012-10-30Bibliographically approved
2. Determination of Dissociation Constants on Quartz Crystal Microbalance Surfaces by Polymer Signal Enhancement
Open this publication in new window or tab >>Determination of Dissociation Constants on Quartz Crystal Microbalance Surfaces by Polymer Signal Enhancement
(English)Manuscript (preprint) (Other academic)
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-25284 (URN)
Note

QC 20101015

Available from: 2010-10-15 Created: 2010-10-15 Last updated: 2016-06-08Bibliographically approved
3. Signal Enhancement in Ligand-Receptor Interactions using Dynamic Polymers at Quartz Crystal Microbalance Surfaces
Open this publication in new window or tab >>Signal Enhancement in Ligand-Receptor Interactions using Dynamic Polymers at Quartz Crystal Microbalance Surfaces
(English)Manuscript (preprint) (Other academic)
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-25122 (URN)
Note
QC 20101008Available from: 2010-10-08 Created: 2010-10-08 Last updated: 2010-10-15Bibliographically approved

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