Electrically Controlled Click‐Chemistry for Assembly of Bioactive Hydrogels on Diverse Micro‐ and Flexible Electrodes

Abstract

The seamless integration of electronics with living matter requires advanced materials with programmable biological and engineering properties. Here electrochemical methods to assemble semi-synthetic hydrogels directly on electronically conductive surfaces are explored. Hydrogels consisting of poly (ethylene glycol) (PEG) and heparin building blocks are polymerized by spatially controlling the click reaction between their thiol and maleimide moieties. The gels are grown as conformal coatings or 2D patterns on ITO, gold, and PtIr. This study demonstrates that such coatings significantly influence the electrochemical properties of the metal-electrolyte interface, likely due to space charge effects in the gels. Further a promising route toward engineering and electrically addressable extracellular matrices by printing arrays of gels with binary cell adhesiveness on flexible conductive surfaces is highlighted.

Electro-assisted assembly of conductive polymer and soft hydrogel into core-shell hybrids

“…The diameters increase with a similar trend as discussed above using kinetics parameters [Figure 2D]. The growth profile of the alginate hydrogel presented here is similar to pure alginate formed over electrodes, tending to reach a plateau for long electrodeposition periods [36] .…”

“…The solution composition was adapted from a previous work [36] . Firstly, 1.0 (w/w) of calcium carbonate was dispersed in 24.3 mL of deionized water, followed by dissolution of 1% (w/w) sodium alginate kept under vigorous stirring for 30 min at room temperature.…”

“…These methods are effective; however, they require additional steps and add complexity to the processing of hybrid structures. As an alternative, electrodeposition methods can offer a simple strategy to facilitate the direct growth of soft materials, especially over conductive substrates, controlling electron transfer and adhesion process at the interface [32,[35][36][37][38] . A number of promising electrochemical approaches have already been reported.…”

“…Recently, we have proposed an electro-assisted method for forming hydrogels on conductive surfaces using an electrochemical-chemical-chemical (ECC) mechanism. This includes deposition of conductive hybrid PEDOT/alginate films [36] . However, application of traditional electrodeposition protocols highlighted several limitations, such as slow growth kinetics and low levels of hydration of the final material.…”

Engineering peptide-modified alginate-based bioinks with cell-adhesive properties for biofabrication

“…[20][21][22][23][24] The alginate polymer chains can be modied directly with these celladhesive peptides or indirectly over modied polyethylene glycol (PEG) moieties, which are also widely used in hydrogel systems for biofabrication studies. [25][26][27] Until today various peptide sequences were used to specically modify natural inert biomaterials, such as ALG. 28,29 For example, the sequence tyrosine-isoleucine-glycine-serine-arginine (YIGSR, Peptide A), found in laminin, 30 was shown to promote neuronal cell adhesion and differentiation, 31 neuronal outgrowth 32 and nerve regeneration.…”