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Using complementary acoustic and optical techniques for quantitative monitoring of biomolecular adsorption at interfaces.

Konradi R, Textor M, Reimhult E - Biosensors (Basel) (2012)

Bottom Line: In this tutorial review, different optical and acoustic evanescent techniques are used to illustrate how an understanding of the transducer principle of each technique can be exploited for further interpretation of hydrated and extended polymer and biological films.The case studies deal with representative examples of adsorption of protein films, polymer brushes and lipid membranes, and describe e.g., how to deal with strongly vs. weakly hydrated films, large conformational changes and ordered layers of biomolecules.The presented systems and methods are compared to other representative examples from the increasing literature on the subject.

View Article: PubMed Central - PubMed

Affiliation: BASF SE, Advanced Materials and Systems Research, D-67056 Ludwigshafen, Germany. rupert.konradi@basf.com.

ABSTRACT
The great wealth of different surface sensitive techniques used in biosensing, most of which claim to measure adsorbed mass, can at first glance look unnecessary. However, with each technique relying on a different transducer principle there is something to be gained from a comparison. In this tutorial review, different optical and acoustic evanescent techniques are used to illustrate how an understanding of the transducer principle of each technique can be exploited for further interpretation of hydrated and extended polymer and biological films. Some of the most commonly used surface sensitive biosensor techniques (quartz crystal microbalance, optical waveguide spectroscopy and surface plasmon resonance) are briefly described and five case studies are presented to illustrate how different biosensing techniques can and often should be combined. The case studies deal with representative examples of adsorption of protein films, polymer brushes and lipid membranes, and describe e.g., how to deal with strongly vs. weakly hydrated films, large conformational changes and ordered layers of biomolecules. The presented systems and methods are compared to other representative examples from the increasing literature on the subject.

No MeSH data available.


(a) Comparison of ‘dry’ mass of adsorbed copolymer () and serum proteins () as obtained from OWLS measurements (see Figure 5(a)) and ‘wet’ mass of adsorbed copolymer () and serum proteins () as obtained from QCM-D measurements using Voigt modelling (see Figure 5(b)) for PLL-g-PMOXA graft copolymers of varying graft density. α = 0 corresponds to pure PLL. Copolymer and serum adsorbed masses were taken after rinsing with buffer after a stable value was reached; (b) Hydration in weight percent of water in the PLL-g-PMOXA adlayers calculated from the data in (a) according to Equation (4).
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biosensors-02-00341-f006: (a) Comparison of ‘dry’ mass of adsorbed copolymer () and serum proteins () as obtained from OWLS measurements (see Figure 5(a)) and ‘wet’ mass of adsorbed copolymer () and serum proteins () as obtained from QCM-D measurements using Voigt modelling (see Figure 5(b)) for PLL-g-PMOXA graft copolymers of varying graft density. α = 0 corresponds to pure PLL. Copolymer and serum adsorbed masses were taken after rinsing with buffer after a stable value was reached; (b) Hydration in weight percent of water in the PLL-g-PMOXA adlayers calculated from the data in (a) according to Equation (4).

Mentions: Similar experiments were conducted for a set of PLL-g-PMOXA of varying grafting density α, where α denotes the number of PMOXA side-chains per lysine unit of the graft copolymer backbone (α = 1/g). In Figure 6(a), the values obtained for the dry polymer and serum adsorbed masses are plotted together with the corresponding wet masses as a function of the grafting density. The curves show a typical behavior: At low grafting densities, increasing the number of side-chains naturally increases the adsorbed copolymer mass, whereas, at high grafting densities, thermodynamic and kinetic reasons such as the diminished electrostatic attraction and a strong side-chain crowding effectively oppose copolymer adsorption [81,84].


Using complementary acoustic and optical techniques for quantitative monitoring of biomolecular adsorption at interfaces.

Konradi R, Textor M, Reimhult E - Biosensors (Basel) (2012)

(a) Comparison of ‘dry’ mass of adsorbed copolymer () and serum proteins () as obtained from OWLS measurements (see Figure 5(a)) and ‘wet’ mass of adsorbed copolymer () and serum proteins () as obtained from QCM-D measurements using Voigt modelling (see Figure 5(b)) for PLL-g-PMOXA graft copolymers of varying graft density. α = 0 corresponds to pure PLL. Copolymer and serum adsorbed masses were taken after rinsing with buffer after a stable value was reached; (b) Hydration in weight percent of water in the PLL-g-PMOXA adlayers calculated from the data in (a) according to Equation (4).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4263558&req=5

biosensors-02-00341-f006: (a) Comparison of ‘dry’ mass of adsorbed copolymer () and serum proteins () as obtained from OWLS measurements (see Figure 5(a)) and ‘wet’ mass of adsorbed copolymer () and serum proteins () as obtained from QCM-D measurements using Voigt modelling (see Figure 5(b)) for PLL-g-PMOXA graft copolymers of varying graft density. α = 0 corresponds to pure PLL. Copolymer and serum adsorbed masses were taken after rinsing with buffer after a stable value was reached; (b) Hydration in weight percent of water in the PLL-g-PMOXA adlayers calculated from the data in (a) according to Equation (4).
Mentions: Similar experiments were conducted for a set of PLL-g-PMOXA of varying grafting density α, where α denotes the number of PMOXA side-chains per lysine unit of the graft copolymer backbone (α = 1/g). In Figure 6(a), the values obtained for the dry polymer and serum adsorbed masses are plotted together with the corresponding wet masses as a function of the grafting density. The curves show a typical behavior: At low grafting densities, increasing the number of side-chains naturally increases the adsorbed copolymer mass, whereas, at high grafting densities, thermodynamic and kinetic reasons such as the diminished electrostatic attraction and a strong side-chain crowding effectively oppose copolymer adsorption [81,84].

Bottom Line: In this tutorial review, different optical and acoustic evanescent techniques are used to illustrate how an understanding of the transducer principle of each technique can be exploited for further interpretation of hydrated and extended polymer and biological films.The case studies deal with representative examples of adsorption of protein films, polymer brushes and lipid membranes, and describe e.g., how to deal with strongly vs. weakly hydrated films, large conformational changes and ordered layers of biomolecules.The presented systems and methods are compared to other representative examples from the increasing literature on the subject.

View Article: PubMed Central - PubMed

Affiliation: BASF SE, Advanced Materials and Systems Research, D-67056 Ludwigshafen, Germany. rupert.konradi@basf.com.

ABSTRACT
The great wealth of different surface sensitive techniques used in biosensing, most of which claim to measure adsorbed mass, can at first glance look unnecessary. However, with each technique relying on a different transducer principle there is something to be gained from a comparison. In this tutorial review, different optical and acoustic evanescent techniques are used to illustrate how an understanding of the transducer principle of each technique can be exploited for further interpretation of hydrated and extended polymer and biological films. Some of the most commonly used surface sensitive biosensor techniques (quartz crystal microbalance, optical waveguide spectroscopy and surface plasmon resonance) are briefly described and five case studies are presented to illustrate how different biosensing techniques can and often should be combined. The case studies deal with representative examples of adsorption of protein films, polymer brushes and lipid membranes, and describe e.g., how to deal with strongly vs. weakly hydrated films, large conformational changes and ordered layers of biomolecules. The presented systems and methods are compared to other representative examples from the increasing literature on the subject.

No MeSH data available.