Regenerating the cell resistance of micromolded PEG hydrogels

Abstract

Polydimethylsiloxane stamp materials used during soft lithography undermine the non-fouling behaviour of bio-inert PEG-based hydrogels, resulting in increased protein adsorption and cell adhesion and migration on the gel. This previously unreported phenomenon undermines the function of lab-on-a-chip devices that require the device to be bio-inert, and slows the implementation of promising micromolding and imprinting methods for 3D culture and commercial cell culture systems. We illustrate that the degree of cell adhesion and protein adsorption to the gels correlates with the amount of residual stamp material remaining at the hydrogel interface after fabrication. After identifying this previously unreported phenomenon, we screened multiple polymer cleaning/fabrication techniques in order to maintain/restore the non-fouling properties of the gels including PDMS curing and extraction, use of other common soft lithography stamp materials, post-fabrication cleaning of the hydrogels, and changing the composition of the hydrogel. The optimal solution was determined to be incorporation of reactive sites into the hydrogel during micromolding followed by grafting of PEG macromers to these sites post-fabrication. This treatment resulted in micromolded hydrogels with robust cell resistant properties. Broadly, this work identifies and solves a previously unreported problem in hydrogel micromolding, and specifically reports the development of a cell culture platform that when combined with video microscopy enables high-resolution in situ study of single cell behaviour during in vitro culture.

Integrin‐Mediated Interactions Control Macrophage Polarization in 3D Hydrogels

“…By extension, this conclusion stipulates that poly(ethylene glycol) (PEG)-based hydrogels are bio-inert [42] and do not present integrin binding sites and are prone to cause M1 macrophage polarization. Further studies with other bio-inert polymers can elucidate whether this conclusion can be generalized.…”

Synergistic influence of collagen I and BMP 2 drives osteogenic differentiation of mesenchymal stem cells: A cell microarray analysis

“…S5). Increasing A-PEG density on the surface resulted in decreasing cell attachment since PEG is known to resist cell attachment [55][56][57]. Cell density is known to regulate MSC osteogenic differentiation through the competitive influences of cell spreading (via cytoskeletal tension) and intercellular contact [58].…”

Preparation, characterization, and protein-resistance of films derived from a series of α-oligo(ethylene glycol)-ω-alkenes on H–Si(111) surfaces

“…Therefore, with at least six EG units, the OEGterminated lms derived from the C 10 EG n series on Si (111) surfaces and prepared at low vacuum conditions ($1 mbar) effectively resisted the protein adsorption, which was comparable to those lms derived from OEG-terminated thiolates on Au (111) surfaces that also displayed increasing protein resistance with longer EG chain length. 49,53,57,78 C 10 EG n lms on Si(111) prepared at medium vacuum conditions…”

“…7,10 Although excellent proteinresistant properties have been demonstrated for zwitterions [34][35][36] and polypeptides 37 coatings, ultrathin lms presenting OEG are still among the most widely used and the most protein-resistant coatings studied to date. [38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57] Moreover, we recently demonstrated that the high resistance to non-specic protein adsorption of OEG lms allows the selective attachment of proteins onto the nanopatterns generated on such lms by local oxidation using conductive atomic force microscopy (AFM). 58,59 We and others have reported the photo-activated graing of the a-OEG-u-alkenes onto hydrogen-terminated silicon, forming OEG-terminated monolayers that are directly bound to the silicon substrate via Si-C bonds (Scheme 1).…”

“…68,69,73 The OEG lms remained protein-resistant aer 1 week in PBS (pH 7.4) at room temperature. 49 Notably, in the literature the protein-resistance of OEG-terminated lms were oen measured aer washing the protein-treated samples with a detergent solution for a relatively long period of time. 75 Such a strong washing procedure resulted in a lower value of the protein adsorption compared to the procedure employed by us.…”