Synthesis and gelation characteristics of photo-crosslinkable star Poly(ethylene oxide-co-lactide-glycolide acrylate) macromonomers

Abstract

Viability of encapsulated cells in situ crosslinkable macromonomers depends strongly on the minimum concentration of polymerization initiators and monomers required for gelation. Novel 4-arm poly(ethylene oxide-co-lactide-glycolide acrylate) (SPELGA) macromonomers were synthesized and characterized with respect to gelation, sol fraction, degradation, and swelling in aqueous solution. SPELGA macromonomers were crosslinked in the absence of N-vinyl-2-pyrrolidone (NVP) monomer to produce a hydrogel network with a shear modulus of 27±4 kPa. The shear modulus of the gels increased by 170-fold as the macromonomer concentration was increased from 10 to 25 wt%. Sol fraction ranged between 8–18%. Addition of only 0.4 mol% NVP to the polymerization mixture increased modulus by 2.2-fold from 27±4 (no NVP) to 60±10 kPa. The higher modulus was attributed to the dilution effect of polymer chains in the sol, by delaying the onset of diffusion-controlled reaction, and cross-propagation of the growing chains with network-bound SPELGA acrylates. Degradation of SPELGA gels depended on water content and density of hydrolytically degradable ester groups.

Experimental and Computational Investigation of the Effect of Hydrophobicity on Aggregation and Osteoinductive Potential of BMP-2-Derived Peptide in a Hydrogel Matrix

“…23,25 Briefly, the residual moisture was removed from the PEG macromer by azeotropic distillation from toluene. The PEG macromer and lactide monomers were heated to 120°C under dry nitrogen atmosphere in a reaction flask equipped with an overhead stirrer.…”

“…Hydrophobicity of the peptide was varied by capping PEG chain ends with 0-6 lactide monomers. PEG as an inert matrix with tunable properties [22][23][24] was used for encapsulation of hMSCs to isolate and investigate the effect of BMP-2 peptide hydrophobicity on its osteoinductive potential. Experimental and simulation results revealed that osteoinductive potential of the BMP-2 peptide is correlated with its CMC and the concentration of free peptide in aqueous medium and not the total peptide concentration.…”

Three-Dimensional-Engineered Matrix to Study Cancer Stem Cells and Tumorsphere Formation: Effect of Matrix Modulus

“…46,47 Based on NMR results, the average degree of acrylation was 89% and there was on average 1.8 -0.1 acrylates in the PEGDA macromer. Disk-shaped hydrogels with 8-mm diameter and 750-mm thickness were fabricated for determination of elastic modulus and cell encapsulation.…”

Hydrogels for Cell Encapsulation and Bioprinting

“…The gelation kinetics of physical micellar gels depends on the strength and number density of physical crosslinks [105,107]. The gelation kinetics of covalently-bonded chemical gels depends on several factors including the concentration and distribution of crosslinkable groups and initiator [104,[108][109][110]. Figure 3a shows the gelation time of photocrosslinkable star poly(ethylene glycol-co-lactide) acrylate (SPELA) macromers with respect to concentration of UV photo-initiator.…”

“…Copolymerization of PEG with a degradable polymer like poly(lactide) (PLA) has been used to impart degradability to PEG hydrogels. The degradation and water content of the copolymers can be adjusted by the fraction of hydrophobic lactide segments [131,132] but solubility of the copolymer in aqueous solution was adversely affected by increasing the lactide content [133]. In addition, other hydrolytically degradable polymers including polyphosphoesters [134,135], poly(ester amides) [136] and poly(amino-ester urethanes) [137] have been used to synthesize degradable hydrogels.…”