Patterned and switchable surfaces for biomaterial applications

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Chapter 5 – Surface plasmon resonance imaging of polymer microarraysComparing cell attachment with the protein adsorption experiments (section5.4.3), a clear correlation between cell attachment and BSA adsorption was observed.This may suggest that cell attachment is mediated by the adsorption of negativelycharged serum proteins, which has previously been reported [306]. Under normal cellculture conditions in the presence of serum cell attachment is observed to occur overa period of a few hours, thus, the kinetics of BSA adsorption would suggest thatprotein is able to adsorb to the surface before cells attach, thus, would be presentwhen cells are attaching to the surface. However, BSA adsorption, which is used toprevent cell attachment [307], is unlikely to mediate cell attachment. The correlationbetween BSA adsorption and cell attachment suggests that both processes occur bythe same underlying mechanism, that is, electrostatic interactions; the overallnegative charge of the cell membrane [308] will be electrostatically attracted to thepositive surface charge of the PEI and PLL spots and likewise be repelled from thenegatively charged PAA spots. However, determining clear correlations betweenprotein-surface interactions and cell attachment behaviour is intrinsically difficultdue to the complex nature of cell attachment, which can be influenced by surfaceproperties such as chemistry, inclusion of biological cues, elastic modulus,wettability, charge and topography as well as cell culture conditions such as the cellline, the concentration of serum and the time period of incubation.It is interesting to note that cell attachment did not occur on the PAAc despite thissurface being suitable for the adsorption of ECM proteins whilst it did occur on PEIcand PLLc, which were seen to resist CN type I adsorption (Figure 5.14 and Table5.1). This result may have implications for long term cell growth on these surfaces,whereupon, PEIc and PLLc may resist the formation of ECM about attached cellsand PAAc may, over time, become susceptible to cell attachment by the adsorption5-204
Andrew Hook – Patterned and switchable surfaces for biomaterial applicationsof secreted collagen fibrils. Moreover, the inclusion of FN and CN in the cell culturemedia may also promote cell attachment on the PAAc.5.5. ConclusionThe characterisation of a polymer array containing non-uniform surface featuresusing SPRi has been achieved, overcoming the requirement for homogeneoussurfaces for comparative SPRi measurements. A method has been developedwhereby changes in reflectivity measured during a typical fixed angle SPRexperiment can be related to the corresponding shift in resonance angle. This processwas shown to theoretically produce equivalent responses for microarray polymerspots of 0-30 nm thickness when exposed to an equivalent change in refractive indexand was found to produce quantitatively comparable results in practice. Thisapproach has been utilised to study the adsorption of CN type I, FN and BSA to apolymer array of PAA, PEI and PLL. For this, a novel approach to producing a lowfouling background for SPR applications was developed by initially coating a SPRchip with a thin plasma polymer layer that was modified with HDI in order to attacha low-fouling PEG layer. BSA adsorption to the polymer array followed the expectedtrends assuming electrostatic interactions, however, CN type I and FN, despitehaving a negative charge, adsorbed on both positively and negatively charged surfacechemistries. The end on adsorption of both these polymers to PAA was suggested.This result highlighted the complex behaviour of biomolecules at surfaces and, thus,the difficulty associated with correlating protein and cellular behaviour.Comparison of protein adsorption studies with cell attachment assays conductedwith SK-N-SH in serum over 24 hr suggest that cell attachment is largely driven byelectrostatic interactions.5-205
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Patterned andswitchable surfacesfor
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TABLE OF CONTENTSTABLE OF CONTENTS
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CHAPTER 1.INTRODUCTION1The content
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Chapter 1 - Introductionconsiderabl
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Chapter 1 - Introductioninteraction
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Chapter 1 - IntroductionIn general,
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Chapter 1 - IntroductionFor some ap
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Chapter 1 - Introductionangles rang
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Chapter 1 - Introductionof understa
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Chapter 1 - IntroductionSeveral str
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Chapter 1 - Introductioncues to con
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Chapter 1 - Introductionby controll
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Chapter 1 - Introduction1.2.2. Soft
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Chapter 1 - Introductionsubstrate.
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Chapter 1 - Introduction(A)(B)Figur
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Chapter 1 - Introduction(A)(B)(C)(C
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Chapter 1 - Introductioncomplex gen
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Chapter 1 - Introductionmorphology
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Chapter 1 - Introduction(A)(B)(C)(D
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Chapter 1 - Introductionthe LCST, a
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Chapter 1 - IntroductionHyun et al.
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Chapter 1 - Introductionmicelles. T
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Chapter 1 - Introduction1.4.1. DNA
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Chapter 1 - IntroductionA major pro
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Chapter 1 - Introductionattached to
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Chapter 1 - IntroductionTable 1.1.
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Chapter 1 - Introductionefficiencie
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Chapter 1 - Introductionachieved by
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Chapter 1 - IntroductionTable 1.2.
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Chapter 1 - IntroductionOnce releas
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Chapter 1 - Introductionimaging not
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Chapter 1 - IntroductionA number of
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CHAPTER 2.SPATIALLY CONTROLLED ELEC
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CHAPTER 3.COMPARISON OF THE BINDING
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DNA (mg/m 2 ) DNA (mg/m 2 )Andrew H
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DNA (mg/m 2 )Andrew Hook - Patterne
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Chapter 4 - Formation of a chemical
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