Conducting hydrogels represent a new generation of ''smart'' biomaterials which combine the favorable biocompatibility properties of hydrogels and electrical properties of organic conductors, and would potentially lead to the development of new biointerfaces with controllable properties. Currently, conductive hydrogels are synthesized by either adding conducting particles to, or polymerizing conducting polymer monomers within, hydrogel matrix, however challenges in processing limit their applications in functional devices. In this work, a poly(ethylene glycol) diacrylate-polyaniline (PEGda-PANI) conductive hydrogel is developed using interfacial polymerization process. In this process, aniline monomers polymerize at the organic/water interface between hexane media and hydrophilic PEGda hydrogel networks. PANI chains become hydrophilic with acid doping and migrate into aqueous phase confined within PEGda networks.The synthesized PEGda-PANI hydrogel has acceptable mechanical, electrical and biocompatible properties. Traditional fabrication methods including process-driven salt-leaching and design-driven projection stereolithography were used to develop 3D scaffolds using PEGda-PANI hydrogels. This methodology can be potentially extended to a wide variety of fabrication techniques to develop hydrogels with complex geometries and next-generation functional biointerfaces.

Measurements on densities, viscosities, and refractive indices at atmospheric pressure for binary mixtures of 1,3-dimethyladamantane (1,3-DMA), 1,3,5-trimethyladamantane (1,3,5-TMA), and 1-ethyladamantane (1-EA) with n-nonane or n-undecane are carried out over the whole composition range at temperatures T = 293.15−343.15 K and atmospheric pressure. The excess molar volume (V m E ), deviation in viscosity (Δη), deviation in refractive index (Δn D ), and deviation in molar refraction (ΔR) for the six mixtures are calculated and then fitted to the Redlich−Kister polynomial. The V m E values are all negative over the entire range of mole fractions and decrease with increasing temperature for the six binary systems. The absolute values of Δη for the mixtures decrease obviously with increasing temperature. The Δn D values with the volume fraction for the six systems are all positive over the entire composition range. Density, viscosities, and refractive index of the six systems are correlated by the Jouyban−Acree model. The experimental results could be useful for the development of high-energy-density hydrocarbon fuels.

Current cell-culture is largely performed on synthetic two-dimensional (2D) petri dishes or permeable supports such as Boyden chambers, mostly because of their ease of use and established protocols. It is generally accepted that modern cell biology research requires new physiologically relevant three-dimensional (3D) cell culture platform to mimic in vivo cell responses. To that end, we report the design and development of a suspended hydrogel membrane (ShyM) platform using gelatin methacrylate (GelMA) hydrogel. ShyM thickness (0.25–1 mm) and mechanical properties (10–70 kPa) can be varied by controlling the size of the supporting grid and concentration of GelMA prepolymer, respectively. GelMA ShyMs, with dual media exposure, were found to be compatible with both the cell-seeding and the cell-encapsulation approach as tested using murine 10T1/2 cells and demonstrated higher cellular spreading and proliferation as compared to flat GelMA unsuspended control. The utility of ShyM was also demonstrated using a case-study of invasion of cancer cells. ShyMs, similar to Boyden chambers, are compatible with standard well-plates designs and can be printed using commonly available 3D printers. In the future, ShyM can be potentially extended to variety of photosensitive hydrogels and cell types, to develop new in vitro assays to investigate complex cell–cell and cell–extracellular matrix (ECM) interactions.

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