Direct functionalization of cell‐adhesion promoters to hydrogel microparticles synthesized by stop‐flow lithography

Abstract

Polyethylene glycol (PEG) hydrogel microparticles generated via stop‐flow lithography can be utilized for efficient microparticle‐based cell culture processes because of their high biocompatibility, the molecular diffusion capability in the gel structure, and the tunability of their shape and size. However, the typical functionalization process of PEG microparticles with cell‐adhesion promoters has inevitable limitations, requiring additional linker molecules and the preconjugation of linkers to cell‐adhesion promoters and microparticles. In this study, a simple and direct cell‐adhesion promoter functionalization process of the PEG microparticles is presented by use of aza‐Michael reaction between remnant unreacted acrylate groups in particles and amine groups in cell‐adhesion promoters. On the basis of proposed process, particles are directly conjugated with poly‐l‐lysine (PLL), a typical cell‐adhesion promoter that can electrostatically interact with cellular membranes, in a controllable manner. We demonstrate enhanced cell‐adhesion capabilities of the particles along with the increased amount of conjugated PLL in the particles. Furthermore, to validate extended applicability, the particles are directly conjugated with Gly‐Arg‐Gly‐Asp‐Ser (GRGDS) peptides, in which RGD sequence is involved in the cell‐adhesion behavior of extracellular matrix proteins, including fibronectin. The introduced GRGDS peptides increase the cell‐adhesion capacity of the microparticles binding to integrin proteins in cellular membranes.

Lab on a Particle Technologies

“…149 Another method of generating adhesive particles is to use the acrylate groups unpolymerized after SFL and conduct an aza-Michael reaction between these acrylate groups and amines in cell adhesion promoters (such as PLL or RGD). 158 Beyond adding proteins to the surface of particles, the surface morphology of the particles can be modified to increase roughness and aid cell adhesion (Figure 9g). 159 Amphiphilic particles that template the formation of droplets within oil were also used to quantify the secretions from cells encapsulated within.…”

“…They demonstrated their ability to culture both endothelial and breast cancer cells on the ECM-functionalized particles . Another method of generating adhesive particles is to use the acrylate groups unpolymerized after SFL and conduct an aza-Michael reaction between these acrylate groups and amines in cell adhesion promoters (such as PLL or RGD) . Beyond adding proteins to the surface of particles, the surface morphology of the particles can be modified to increase roughness and aid cell adhesion (Figure g) …”

Microgels for Cell Delivery in Tissue Engineering and Regenerative Medicine

“…Apart from hydrogels, other materials are also widely used to fabricate microparticles with complex structures. It is worth mentioning that multicompartmental microparticles have attracted considerable attention in the biomedical field because a single microparticle can carry multiple materials with different components well separated from each other to achieve versatilities [54][55][56]. When a variety of resins were used, it was possible to produce angularly segmented flows distinct from laminar flow, forming microparticles with separate compartments (Fig.…”

Protecting group-free introduction of amino acids to polymers through the aza-Michael reaction

“…The Michael addition is increasingly popular in materials chemistry as a mechanism to bridge amino acids or peptides to polymers. [24][25][26][27] For example, the thia-Michael reaction links proteins or peptides with polymers through the side chain of cysteine, [28][29][30][31] which conveys new properties to functional materials, including self-assembly, 32 celladhesion, 33 and other tailored bio-activities. 34,35 The aza-Michael addition analogously links other amine-containing molecules to amino acids first modified with acryloyl chloride.…”