A New Planar-Type Leakage Current and Impedance Microsensor for Detection of Interaction between Electrolyte- Entrapping Liposome and Protein

AbstractWe have developed a new leakage current microsensor by using simpler planar processes than Si-surface-bulk micromachining processes used in the previous microwell structure. This sensor fabrication and structure can easily make a target solution volume smaller than μL with excellent immobilization of the droplet and intact biomolecules as sensing elements, as a result, reduce effectively the background noise current in the microsensor and improve reproducibility of the results. The leakage current due to the biochemical interaction was successfully evaluated, dependent on the droplet protein concentration. Cole-Cole plots from the impedance analysis also show quantitative difference between with and without the interaction, depending on the charge-transfer impedance that results from the condition and structure of liposome and lipid membrane after the interaction

A highly-sensitive leakage current microsensor by using denaturant: detection of target protein by DPPC liposome

AbstractWe have developed a highly-sensitive leakage current microsensor by using the DPPC liposome entrapping K4[Fe(CN)6] solution to detect existence of biomolecules especially proteins and their dynamic conditions. In this work, the addition of guanidinium hydrochloride (GuHCl) as protein denaturant successfully obtain a prominent improvement in sensitivity by 129-fold of magnitude, although target protein, which is carbonic anhydrase from bovine (CAB), weakly interacts with liposome under the normal condition. Moreover, we can use it to evaluate the conformation state of CAB protein such as ‘Native’, ‘Molten-Globule’ and ‘Unfold’ states