VISUALIZATION OF MICRO-STRUCTURED ENZYME PATTERNS USING SCANNING ELECTROCHEMICAL MICROSCOPY (SECM)

摘要

Two novel approaches for local structuring surfaces with biomolecules in micrometer dimensions are described. Both methods are based on a polymer which changes dramatically its solubility in aqueous solutions when it is protonated as a consequence of a modulation of the pH-value. If high-molecular weight biological recognition compounds are present in the solution they can be entrapped during the deposition process which is electrochemically induced by changing of the pH-value. The first immobilization method is based on a localization using a positioned microelectrode in close distance to a conducting surface. Shifting of the pH-value by application of potential pulses to the conducting surface underneath the microelectrode leads to a micro-structured deposition of the polymer. The second immobilization technique is based on a high-precision piezo-based microdispenser, capable of shooting single droplets with volumes as small as 100 pL. Filling the dispenser with polymer suspension and enzyme and shooting droplets onto a surface leads to the formation of polymer microstructures with entrapped enzyme. Scanning Electrochemical Microscopy (SECM) has been applied to visualize the immobilized enzyme activity in these microstructures with high spatial resolution.