Real-Time and In-Situ Monitoring of H2O2 Release from Living Cells by a Stretchable Electrochemical Biosensor Based on Vertically Aligned Gold Nanowires (original) (raw)
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Characterization of Nanoporous Gold Electrodes for Bioelectrochemical Applications
Langmuir, 2012
The high surface areas of nanostructured electrodes can provide for significantly enhanced surface loadings of electroactive materials. The fabrication and characterization of nanoporous gold (np-Au) substrates as electrodes for bioelectrochemical applications is described. Robust np-Au electrodes were prepared by sputtering a goldÀsilver alloy onto a glass support and subsequent dealloying of the silver component. Alloy layers were prepared with either a uniform or nonuniform distribution of silver and, post dealloying, showed clear differences in morphology on characterization with scanning electron microscopy. Redox reactions under kinetic control, in particular measurement of the charge required to strip a gold oxide layer, provided the most accurate measurements of the total electrochemically addressable electrode surface area, A real . Values of A real up to 28 times that of the geometric electrode surface area, A geo , were obtained. For diffusion-controlled reactions, overlapping diffusion zones between adjacent nanopores established limiting semi-infinite linear diffusion fields where the maximum current density was dependent on A geo . The importance of measuring the surface area available for the immobilization was determined using the redox protein, cyt c. The area accessible to modification by a biological macromolecule, A macro , such as cyt c was reduced by up to 40% compared to A real , demonstrating that the confines of some nanopores were inaccessible to large macromolecules due to steric hindrances. Preliminary studies on the preparation of np-Au electrodes modified with osmium redox polymer hydrogels and Myrothecium verrucaria bilirubin oxidase (MvBOD) as a biocathode were performed; current densities of 500 μA cm À2 were obtained in unstirred solutions.
ACS Sensors, 2016
Online detection and accurate quantification of superoxide anions released from skeletal muscle tissue is important in both physiological and pathological contexts. Above certain physiologically redundant levels, superoxides may exert toxic effects. Here we present design, fabrication, and successful testing of a highly sensitive electrochemical superoxide biosensor based on nanoporous gold (NPG) immobilized with cytochrome-c (cyt-c). A significant 14-fold enhancement in the biosensor sensitivity was achieved using NPG instead of nonporous gold, enabling the device to quantify minuscule levels of superoxides. Such improvement was attributed to the very large surface-to-volume ratio of the NPG network. The average values of superoxide sensitivity and analytical limit of detection (LOD) were 1.90 ± 0.492 nA nM −1 cm −2 and 3.7 nM, respectively. The sensor was employed to measure the rates of superoxide release from C2C12 myoblasts and differentiated myotubes upon stimulation with an endogenous superoxideproducing drug. To account for the issue of sensor-to-sensor sensitivity variations, each sensor was individually calibrated prior to measurements of biologically released superoxides. For the drug concentrations studied, C2C12 superoxide generation rates varied from 0.03 to 0.2 pM min −1 cell −1 , within the range of superoxide release rates from normally contracting to fatiguing skeletal muscle tissue. Electrochemically obtained results were validated using a fluorescent superoxide probe. Compared to other destructive methods, the NPG-based electrochemical biosensor provides unique advantages in tissue engineering because of its higher sensitivity and the ability to measure the levels of biologically released superoxides in real-time.
Design of Stretchable Holey Gold Biosensing Electrode for Real-Time Cell Monitoring
In bioelectronics, gold thin films have been widely used as sensing electrodes for probing biological events due to their high conductivity, chemical inertness, biocompatibility, wide electrochemical window and facile surface modification. However, they are intrinsically not stretchable, which limits their applications in detecting biological reactions when soft biological system is mechanically deformed. Here, we report on nanosphere lithography-based strategy to generate ordered microhole gold thin film electrodes supported by elastomeric substrates. Both experimental and theoretical studies show that the presence of microholes substantially suppresses the catastrophic crack propagation-the main reason for electrical failure for continuous gold film. As a result, the holey gold film achieves a ~94% stretchable limit after which conductivity is lost, in contrast to ~4% for non-structured counterpart. Furthermore, the pinhole gold electrode is successfully used to monitor H2O2 released from living cells under dynamic stretching conditions.
A CHEMICALLY-SENSITIVE NANOWIRE SENSOR ARRAY FOR SENSING OF H2O2 AND pH IN PHYSIOLOGICAL SOLUTIONS
2013
We provide a surface modification to silicon nano-wire field-effect transistor (SiNW-FET) that allows detection of H2O2 and pH in cell culture medium. This modification includes a mono-layer consisting of 9,10-dihydroxyanthracene which can be easily oxidized and reduced back. Furthermore, in physiological solution, 9,10-dihydroxyanthracene readily acts as a donor or acceptor of protons, making it a robust candidate for pH sensing. Significances include: (1) Concentration-dependent sensing responses to H2O2 and pH were verified to cover physiological concentration ranges; (2) Detection limit of 100 nM for H2O2 and <0.2 pH units in cell culture medium; (3) Reusable sensing monolayer that easily recycled.
Individually addressable microelectrode array for monitoring oxygen and nitric oxide release
Analytical and Bioanalytical Chemistry, 2008
We have fabricated a six individual addressable gold working electrode microarray. The device is wirebonded to an eight-pin DIL package that can be easily interconnected to an external multi-channel potentiostat. A polyion complex film coating on the electrode surface provides a suitable coating for the growth of cells. The responses of oxygen and nitric oxide were assessed on uncoated and coated devices using electroanalytical methods. The film coating reduced the diffusion current by approximately 20% in both cases. No changes in the electrochemical mechanism were observed. Simultaneous recordings were obtained for 2 h in the presence of the cells, thus the device is stable for the duration of the bioanalytical measurements. Measurements were conducted to study the simultaneous changes in oxygen and nitric oxide levels in cultured fibroblast cells in the presence of growth hormones that cause cell proliferation. Increases in oxygen consumption of the cells were coupled with increases in nitric oxide levels when in the presence of the growth hormones. Use of a biological detergent to cause an oxidative burst resulted in a large increase in the current for potentials set to detect nitric oxide and oxygen.
Analytical Chemistry, 2012
There is a high demand for simple, rapid, efficient, and user-friendly alternative methods for the detection of cells in general and, in particular, for the detection of cancer cells. A biosensor able to detect cells would be an all-inone dream device for such applications. The successful integration of nanoparticles into cell detection assays could allow for the development of this novel class of cell sensors. Indeed, their application could well have a great future in diagnostics, as well as other fields. As an example of a novel biosensor, we report here an electrocatalytic device for the specific identification of tumor cells that quantifies gold nanoparticles (AuNPs) coupled with an electrotransducing platform/sensor. Proliferation and adherence of tumor cells are achieved on the electrotransducer/detector, which consists of a mass-produced screenprinted carbon electrode (SPCE). In situ identification/ quantification of tumor cells is achieved with a detection limit of 4000 cells per 700 µL of suspension. This novel and selective cell-sensing device is based on the reaction of cell surface proteins with specific antibodies conjugated with AuNPs. Final detection requires only a couple of minutes, taking advantage of the catalytic properties of AuNPs on hydrogen evolution. The proposed detection method does not require the chemical agents used in most existing assays for the detection of AuNPs. It allows for the miniaturization of the system and is much cheaper than other expensive and sophisticated methods used for tumor cell detection. We envisage that this device could operate in a simple way as an immunosensor or DNA sensor. Moreover, it could be used, even by inexperienced staff, for the detection of protein molecules or DNA strands. Yin, T.; Wiegraebe, W.; He, X. C.; Miller, D.; Stark, D.; Perko, K.; Alexander, R.; Schwartz, J.; Grindley, J. C.; Park, J.; Haug, J. S.; Wunderlich, J. P.; Li, H.; Zhang, S.; Johnson, T.; Feldman, R. A.; Li, L. Nature 2009, 457, 97-101. (3) Savage, P. A.; Vosseller, K.; Kang, C.; Larimore, K.; Riedel, E.; Wojnoonski, K.; Jungbluth, A. A.; Allison, J. P. Science 2008, 319, 215-220. (4) Manganas, L. N.; Zhang, X.; Li, Y.; Hazel, R. D.; Smith, S. D.; Wagshul, M. E.; Henn, F.; Benveniste, H.; Djuri, P. M.; Enikolopov, G.; Maleti-Savati, M. Science 2007, 318, 980-985. (5) Smith, J. E.; Medley, C. D.; Tang, Z.; Shangguan, D.; Lofton, C.; Tan, W.