Dynamic, Electronically Switchable Surfaces for Membrane Protein Microarrays

Abstract

Microarray technology is a powerful tool that provides a high throughput of bioanalytical information within a single experiment. These miniaturized and parallelized binding assays are highly sensitive and have found widespread popularity especially during the genomic era. However, as drug diagnostics studies are often targeted at membrane proteins, the current arraying technologies are ill-equipped to handle the fragile nature of the protein molecules. In addition, to understand the complex structure and functions of proteins, different strategies to immobilize the probe molecules selectively onto a platform for protein microarray are required. We propose a novel approach to create a (membrane) protein microarray by using an indium tin oxide (ITO) microelectrode array with an electronic multiplexing capability. A polycationic, protein- and vesicle-resistant copolymer, poly(l-lysine)-grafted-poly(ethylene glycol) (PLL-g-PEG), is exposed to and adsorbed uniformly onto the microelectrode array, as a passivating adlayer. An electronic stimulation is then applied onto the individual ITO microelectrodes resulting in the localized release of the polymer thus revealing a bare ITO surface. Different polymer and biological moieties are specifically immobilized onto the activated ITO microelectrodes while the other regions remain protein-resistant as they are unaffected by the induced electrical potential. The desorption process of the PLL-g-PEG is observed to be highly selective, rapid, and reversible without compromising on the integrity and performance of the conductive ITO microelectrodes. As such, we have successfully created a stable and heterogeneous microarray of biomolecules by using selective electronic addressing on ITO microelectrodes. Both pharmaceutical diagnostics and biomedical technology are expected to benefit directly from this unique method.

Polyelectrolyte Coatings with a Potential for Electronic Control and Cell Sheet Engineering

“…[28] Recently, polyelectrolyte mono-and multilayers have been shown to desorb from conducting substrates upon electrochemical polarization of the substrate. [29][30][31] Based on these results, we have developed a new technique for harvesting cell sheets consisting of two steps: the growth of cells to confluence onto polyelectrolyte thin films and subsequent detachment under electrochemical control. Osteoblasts and fibroblasts grown onto PLL-g-PEG/ PEG-RGD coated indium tin oxide (ITO) could be detached as a cell sheet after the application of a positive potential.…”

“…Moreover, when grown to confluence on mono-or multilayered films made of (PLL/HA) or (PLL/PGA), osteoblasts, fibroblasts and human periodontal ligament cell sheets spontaneously detached, without the need for electrochemical polarization. It has been previously shown [29,31] that a PLL-g-PEG monolayer on metal oxide can be desorbed by electrochemical polarization of the substrate. Similarly, we could completely desorb a PLL-g-PEG/PEG-RGD monolayer from ITO by applying a positive potential for a short time.…”

Protein adsorption behaviors on chitosan/poly(ɛ-caprolactone) blend films studied by quartz crystal microbalance with dissipation monitoring (QCM-D)

“…PCL (Tone-P767) was supplied in pellet form by Dow Chemical Ltd (USA) and had a density of 1.145 g/cm 3 and a weight average molecular weight (Mw) of 50000 g/mol. Chitosan (~85% degree of deacetylation, viscosity: 260 cps) was purchased from Jinan Haidebei Marine Bioengineering Co. Ltd. (Shandong, China), and refined twice by dissolving it in dilute acetic acid solution and then precipitating from dilute ammonia.…”

“…Protein adsorption onto biomaterial surfaces plays a key role in many biomedical and biotechnical applications such as tissue engineering [1] , drug delivery [2] and diagnostics [3] . It is well known that medical devices and biomaterials immediately and spontaneously acquire a layer of host proteins in the very early process of implantation, prior to interacting with host cells, and consequently, the types, ratios, conformations, and orientations of the adsorbed proteins which mainly depend on the chemical, physical, and morphological characteristics of the biomaterial surface may modulate the host cell reactions, such as adhesion, migration and apoptosis, and finally affect the short-and long-term tissue responses [4] .…”

Intelligent Control of Surface Hydrophobicity

“…Tang et al [56] passivated an indium tin oxide (ITO) microelectrode array by uniformly coating the surface with a protein-resistant polyA C H T U N G T R E N N U N G (llysine)-graft-polyethylene glycol (PLL-g-PEG) copolymer. The application of a + 1.8-V electric potential to individual ITO microelectrodes resulted in the localised release of the polymer, which revealed a bare ITO surface for subsequent biological immobilisation.…”