Brian L Hassler | PubMed Health

PubMed2006

Tethered lipid bilayers on electrolessly deposited gold for bioelectronic applications.

This paper presents the formation of a novel biomimetic interface consisting of an electrolessly deposited gold film overlaid with a tethered bilayer lipid membrane (tBLM). Self-assembly of colloidal gold particles was used to create an electrolessly deposited gold film on a glass slide. The properties of the film were characterized using field-effect scanning electron microscopy, energy dispersive spectroscopy, and atomic force microscopy. Bilayer lipid membranes were then tethered to the gold film by first depositing an inner molecular leaflet using a mixture of 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine-N-[3-(2-pyridyldithio)propionate], 1,2-di-O-phytanyl-sn-glycero-3-phosphoethanolamine (DPGP), and cystamine in ethanol onto a freshly prepared electrolessly deposited gold surface. The outer leaflet was then formed by the fusion of liposomes made from DPGP or 1,2-dioleoyl-sn-glycero-3-phosphocholine on the inner leaflet. To provide functionality, two membrane biomolecules were also incorporated into the tBLMs: the ionophore valinomycin and a segment of neuropathy target esterase containing the esterase domain. Electrochemical impedance spectroscopy, UV/visible spectroscopy, and fluorescence recovery after pattern photobleaching were used to characterize the resulting biomimetic interfaces and confirm the biomolecule activity of the membrane. Microcontact printing was used to form arrays of electrolessly deposited gold patterns on glass slides. Subsequent deposition of lipids yielded arrays of tBLMs. This approach can be extended to form functional biomimetic interfaces on a wide range of inexpensive materials, including plastics. Potential applications include high-throughput screening of drugs and chemicals that interact with cell membranes and for probing, and possibly controlling, interactions between living cells and synthetic membranes. In addition, the gold electrode provides the possibility of electrochemical applications, including biocatalysis, bio-fuel cells, and biosensors.

Colloids↗

PubMed2005

Versatile bioelectronic interfaces based on heterotrifunctional linking molecules.

Bioelectronic interfaces that allow dehydrogenase enzymes to communicate with electrodes have potential applications such as biosensors and biocatalytic reactors. A major challenge in creation of such bioelectronic interfaces is to orient the enzyme, its cofactor, and an electron mediator properly with respect to the electrode in order to achieve efficient, multistep electron transfer. This paper describes a versatile, new method that uses cysteine, an inexpensive, branched amino acid having sulfhydryl, amino, and carboxyl functional groups, to achieve such orientation. This approach provides greater flexibility in assembling complex bioelectronic interfaces than previously reported approaches that bind the enzyme, cofactor, and mediator in a linear chain. Cysteine was attached to a gold electrode through the sulfhydryl groups, to the electron mediator toluidine blue O (TBO) through the carboxyl group, and to the cofactor (e.g., NAD(P)+) through the amino group. Cyclic voltammetry, impedance spectroscopy, chronoamperometry and quartz crystal microbalance gravimetry were used to demonstrate the sequential assembly steps and the electrical activity of the resulting bioelectronic interface.

Alcohol Dehydrogenase↗