Biostack: Nontoxic Metabolite Detection from Live Tissue

There is increasing demand for direct in situ metabolite monitoring from cell cultures and in vivo using implantable devices. Electrochemical biosensors are commonly preferred due to their low-cost, high sensitivity, and low complexity. Metabolite detection, however, in cultured cells or sensitive tissue is rarely shown. Commonly, glucose sensing occurs indirectly by measuring the concentration of hydrogen peroxide, which is a by-product of the conversion of glucose by glucose oxidase. However, continuous production of hydrogen peroxide in cell media with high glucose is toxic to adjacent cells or tissue. This challenge is overcome through a novel, stacked enzyme configuration. A primary enzyme is used to provide analyte sensitivity, along with a secondary enzyme which converts H₂ O₂ back to O₂ . The secondary enzyme is functionalized as the outermost layer of the device. Thus, production of H₂ O₂ remains local to the sensor and its concentration in the extracellular environment does not increase. This "biostack" is integrated with organic electrochemical transistors to demonstrate sensors that monitor glucose concentration in cell cultures in situ. The "biostack" renders the sensors nontoxic for cells and provides highly sensitive and stable detection of metabolites.

Synthesis of Poly(3,4-ethylenedioxythiophene)-Platinum and Poly(3,4-ethylenedioxythiophene)-Poly(styrenesulfonate) Hybrid Fibers by Alternating Current Bipolar Electropolymerization

Alternating current (ac) bipolar electropolymerization of 3,4-ethylenedioxythiophene (EDOT) was performed in the presence of hexachloroplatinate ([PtCl₆]^2-) or poly(styrenesulfonate) (PSS). We demonstrated that both [PtCl₆]^2- and PSS were successfully incorporated into electrogenerated poly(3,4-ethylenedioxythiophene) (PEDOT) as dopants to offer hybrid fibers composed of (i) PEDOT and platinum nanoparticles (PtNPs) (PEDOT-Pt hybrid fibers) and (ii) PEDOT and PSS (PEDOT-PSS hybrid fibers), respectively, in one step, grown from the very edges of Au wires used as bipolar electrodes (BPEs).

Electrodeposition of ZnCo2O4 nanoparticles for biosensing applications

Electrochemical sensing properties of electrodeposited ZnCo₂O₄ nanoparticles towards glucose and dopamine are investigated.

Electrochemical Reactivity on Conducting Polymer Alloys

Embedding macromolecules and active centers such as inorganic nanoparticles into conducting polymers (CPs) has been an ongoing challenge due to the normally harsh conditions required during chemical or electrochemical polymerization that limits the selection of the functional molecules to be incorporated. By developing alternative approaches for incorporating various organic and inorganic materials into CPs it has been possible to obtain efficient charge transfer within the alloys. In this report, two facile techniques are discussed for obtaining such composites: 1) In-situ polymerisation of poly (3,4-ethylenedioxythiophene) (PEDOT) in the presence of non-conducting polymers and 2) electrochemical deposition in-organic nanoparticles inside PEDOT.