Electroconductive hydrogels (ECHs) were prepared as blends of ultraviolet cross-linked poly(hydroxyethyl methacrylate) [poly(HEMA)]-based hydrogels and in situ electrochemically synthesized polypyrrole (PPy). ECH blends, with potential for neuronal prosthetic devices, implantable biosensors, and electro-stimulated release devices, were produced on surface functionalized microfabricated and planar gold electrodes. Hydrogels were synthesized from hydroxyethyl methacrylate (HEMA), poly(ethylene glycol) monomethacrylate (PEGMA), N-[tris(hydroxymethyl)methyl]-acrylamide (HMMA), and 3-sulfopropyl methacrylate potassium salt (SPMA) to produce p(HEMA-co-PEGMA-co-HMMA-co-SPMA). The electroconductive polymer component was electropolymerized from pyrrole and 4-(3'-pyrrolyl)butyric acid to form P(Py-co-PyBA) within the electrode-supported hydrogel. The dynamic electrochemical properties of Au_*|Gel-P(Py-co-PyBA) were investigated using multiple scan rate cyclic voltammetry and electrical/electrochemical impedance spectroscopy (EIS) over the range 0.1–100 kHz and compared to Au_*, Au_*|Gel, and Au_*|PPy. At 0.1 Hz, there was a three-fold decrease in the magnitude of the absolute impedance, subsequent to electropolymerization. The in vitro biocompatibility and cytotoxicity of the polymer-modified gold surfaces were investigated using murine pheochromocytoma (PC12) cells and human muscle fibroblasts (RMS13). For Au_*|Gel-P(Py-co-PyBA) polymer films prepared with different electropolymerization times of 5, 25, and 50 s, there was an increase in cell proliferation of 49%, 61%, and 6% compared to initial cell seeding. These ECH blends have the desired characteristics of low interfacial impedance and noncytotoxicity that makes them good candidates for in vivo intramuscular and neural studies.

Gelatin/chitosan particles suitable for application in ocular drug administration were prepared by a two-step cross-linking process performed in an emulsion-phase separation system. The particles were characterized by scanning electron microscopy and laser diffractometry, and the diameters were 0.202–4.596 µm. The microparticles pH-dependent behavior was monitored by their mean diameter changes in aqueous environment. Adrenalin was drug used to study loading and release characteristics. The prepared particles were nontoxic, with the DL₅₀ values of 6.9–8.19 g/kg body mass. The in vivo biocompatibility tests consisted of subcutaneous administration of a microparticle suspension in physiological serum followed by morpho histological analysis of the implantation site. The in vivo adrenalin ocular delivery was tested on both animals and a voluntary human patient to determine the adrenalin action and by tears. The particles showed good adherent properties without irritation to the patient; adrenalin was released cleared the ocular congestion.