Figure 3.

(A) Schematic of ideal hybrid configuration and photo comparison of hybrid material created from using a bound dopant (B), compared to stratified composite produced from using a free dopant (C), both material samples are hydrated. (D) Charge storage capacity of hybrids calculated from CV performed versus Ag/AgCl at 120mV s⁻¹ from −700 to 700mV over 850 cycles. (E) Elastic moduli (calculated from DMT model) under hydrated conditions, compared to Pt, homogeneous CPs and neural tissue. Reproduced with permission.[13] Copyright 2012. (F) Diameters of the PLGA fibers were distributed over the range 40–500 nm with the majority being between 100–200 nm. (G) Electropolymerized PEDOT nanotubes on the electrode site of an acute neural probe tip after removing the PLGA core fibers. (H) A section of (G) cut with a focused ion beam showing the silicon substrate layer and PEDOT nanoscale fiber coating. (I) Higher-magnification image of (H) showing the PEDOT nanotubes crossing each other. (J) A single PEDOT nanotube which was polymerized around a PLGA nanoscale fiber, followed by dissolution of the PLGA core fiber. This image shows the external texture at the surface of the nanotube. (K) Higher-magnification image of a single PEDOT nanotube demonstrating the textured morphology that has been directly replicated from the external surface of the electrospun PLGA fiber templates. The average wall thickness of PEDOT nanotubes varied from 50–100 nm, with the nanotube diameters ranging from 100 to 600 nm. Schematic illustration of the controlled release of dexamethasone: (L) dexamethasone-loaded electrospun PLGA, (M) hydrolytic degradation of PLGA fibers leading to release of the drug, and (N) electrochemical deposition of PEDOT around the dexamethasone-loaded electrospun PLGA fiber slows down the release of dexamethasone. (O) PEDOT nanotubes in a neutral electrical condition. (P, Q) External electrical stimulation controls the release of dexamethasone from the PEDOT nanotubes due to contraction or expansion of the PEDOT. By applying a positive voltage, electrons are injected into the chains and positive charges in the polymer chains are compensated. To maintain overall charge neutrality, counterions are expelled towards the solution and the nanotubes contract. This shrinkage causes the drugs to come out of the ends of tubes. (R) Cumulative mass release of dexamethasone from: PLGA nanoscale fibers (black squares), PEDOT-coated PLGA nanoscale fibers (red circles) without electrical stimulation, and PEDOT-coated PLGA nanoscale fibers with electrical stimulation of 1 V applied at the five specific times indicated by the circled data points (blue triangles). (S) UV absorption of dexamethasone- loaded PEDOT nanotubes after 16 h (black), 87 h (red), 160 h (blue), and 730 h (green). The UV spectra of dexamethasone have peaks at a wavelength of 237 nm. Data are shown with a ± standard deviation (n = 15 for each case). Reproduced with permission.[68] Copyright 2006.