Effect of macromer synthesis time on the properties of the resulting poly(β‐amino ester) degradable hydrogel

Abstract

Poly(b-amino ester) biodegradable hydrogels are common in biomedical applications because of their tunable properties and similarities to natural soft tissue. Previous work has shown property adjustments through the choice of monomers, the ratio between monomers and the addition of a crosslinking component. Here, we show that the reaction time for the creation of the macromer can affect the resulting hydrogel properties, and thus provides another method of tuning properties. Macromer was created through the reaction of isobutylamine with poly(ethylene glycol) diacrylate (n ¼ 400). The reaction progress was analyzed using IR and GPC analysis. Hydrogels were created through UV photopolymerization from macromers synthesized for 24, 36, and 48 h. The degradation, compressive moduli, and swelling were measured in an aqueous solution. All showed significant differences between hydrogels of different macromer synthesis times. These differences likely stem from the incomplete macromer synthesis reaction and resulting PEG-rich regions in hydrogels from shorter synthesis times. These regions will not readily degrade, but do increase the mechanical properties and extent of swelling.

Synthesis and analysis of degradation, mechanical and toxicity properties of poly(β-amino ester) degradable hydrogels

“…As mentioned previously, a brief macromer synthesis study was carried out to determine the optimal time for the reaction [18]. It is our thought that there is an initial conversion of reactants to products followed by a slower reaction between the macromers to create larger molecular weight molecules.…”

“…Macromers were synthesized as outlined previously [3,17,18]. Briefly, the diacrylate and amine were weighed out to meet the desired molar ratios and reacted in a sealed round bottom flask maintained at 85°C.…”

“…To obtain the desired properties for a given hydrogel application, susceptible domains can be strategically incorporated into the polymer structure at several places: attached to the ends of the oligomer, on the pendant groups attached to the central chain or in the backbone polymer itself [10]. Several biodegradable hydrogel systems have been developed and studied, including those based on poly(ethylene glycol) [4,11,12], polyanhydrides [13,14] and poly(b-amino esters) [3,[15][16][17][18].…”

Drug release from calcium sulfate-based composites

“…20,32 To review, polyethylene glycol (PEG) 400 diacrylate (Polysciences, Inc., Warrington, PA) and isobutylamine (Sigma-Aldrich, St. Louis, MO) were combined in a 1.2:1 molar ratio and placed in a flask partially submerged in a silicon oil bath pre-heated to 85°C. The reaction mixture was continuously stirred for 48 hr and then removed from the heat.…”

“…31–33 In particular, the poly(β-amino ester) (PBAE) family of hydrogels has properties that are easily tuned to achieve great control as a drug delivery vehicle. 32,34,35 Previous research has shown that PBAE particles can be homogeneously embedded into a CS matrix, which may allow further control over the release of drug from these particles as the CS matrix erodes. 20 …”