Non-specific adsorption of molecules to surfaces is a significant issue associated with liquid-based microanalytical systems, such as polymeric microfluidic chips. In microanalytical systems physiological samples are separated into their components and then the amount of each component present can often be measured. What will happen though, if the biomarker that we are looking at is retained elsewhere in the system due to non-specific adsorption? The amount measured will be an underestimation: this means that we could, for example, misdiagnose a patient in a potentially life-threatening way.
No surprise then that a lot of attention is given to preventing non-specific adsorption. One universal approach is to coat the microchip surface with a chemical which limits the adsorption. The Holy Grail, of course, is a coating which has a broad utility and at the same time can be applied quickly to the surface – and stay on it!
Niels Larsen and colleagues, from Technical University of Denmark, describe a potential breakthrough in Lab on a Chip a one-step procedure for surface modification with the polymer polyethylene glycol (PEG). The researchers use PEG coupled to benzophenone: a small molecule that, when exposed to UV light, reacts with the polymer that makes up the microchip, thus immobilizing the coating on the microchip channel wall surfaces.
Larsen and colleagues test how well this coating can inhibit the non-specific binding of a wide variety of molecules to the surface. They find that it limits the adsorption of proteins and DNA molecules. Most interestingly though, they discover that it is quite efficient in restricting the adsorption of many drugs of a varying degree of hydrophobicity, even in very low, physiologically relevant concentration regimes.
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One-step polymer surface modification for minimizing drug, protein, and DNA adsorption in microanalytical systems
Esben Kjær Unmack Larsen and Niels B. Larsen
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Published on behalf of Rafal Marszalek, Molecular BioSystems web science writer. Rafal is an Assistant Editor of Genome Biology at BioMed Central