Controlling poly(β-amino ester) network properties through macromer branching

Abstract

Photopolymerizable and degradable biomaterials are becoming important in the development of advanced materials in the fields of tissue engineering, drug delivery, and microdevices. We have recently developed a library of poly(beta-amino ester)s (PBAEs) that form networks with a wide range of mechanical properties and degradation rates that are controlled by simple alterations in the macromer molecular weight or chemical structure. In this study, the influence of macromer branching on network properties was assessed by adding the trifunctional monomer pentaerythritol triacrylate (PETA) during synthesis. This led to a dose-dependent increase in the network compressive modulus, tensile modulus, and glass transition temperature, and a decrease in the network soluble fraction, yet led to only minor variations in degradation profiles and reaction behavior. For instance, the tensile modulus increased from 1.98+/-0.09MPa to 3.88+/-0.20MPa when the macromer went from a linear structure to a more branched structure with the addition of PETA. When osteoblast-like cells were grown on thin films, there was an increase in cell adhesion and spreading as the amount of PETA incorporated during synthesis increased. Towards tissue engineering applications, porous scaffolds were fabricated by photopolymerizing around a poragen and then subsequently leaching the poragen. Interconnected pores were observed in the scaffolds and observed trends translated to the porous scaffold (i.e., increasing mechanics with increasing branching). These findings demonstrate a simple variation during macromer synthesis that can be used to further tune the physical properties of scaffolds for given applications, particularly for candidates from the PBAE library.

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

“…The cell density was slightly lower in the direct attachment studies; however, these results may be slightly biased due to the cell counting issues discussed previously. With the properties reported, both of these systems could be applicable in a range of tissue engineering applications, and several other methods have been reported for tuning the degradation, mechanical properties and cellular response [15,16]. Ongoing studies are being completed to adjust hydrogel properties and to improve cellular responses to the systems.…”

“…Subsequent work used similar monomers to form acrylated macromers by reacting the amine with excess diacrylate [17], resulting in biodegradable hydrogels with highly tunable properties governed by the choice of chemicals [17], the ratio of diacrylate to amine [3,15] and the addition of a crosslinking molecule [16]. The degradation and mechanical properties of these hydrogel systems have been analyzed [23] as well as their use as crosslinkers in other hydrogel networks [24].…”

“…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].…”

Controlling Stem Cell Fate with Material Design

“…The materials in these studies are also inexpensive and much easier to synthesize than scaffolds possessing complex chemistries and cell recognition sites. [41][42][43] These studies indicate that biomaterial design does not need to exactly mimic native tissue, but rather possess the fundamental characteristics that promote desired stem cell behavior.…”

Preparation and physicochemical characterization of camptothecin conjugated poly amino ester–methyl ether poly ethylene glycol copolymer

“…The inherent CMC values of polymeric micelles are inuenced by the molecular weight of block copolymers, the hydrophobicity of hydrophobic block, as well as the block length and ratio of blocks. 30 Increasing the CPT percentage leads to an increase in hydrophobic interaction at the core of micelles and causes facilitating the formation of nanomicelles. Inter-molecular interactions such as electrostatic interactions, chemical cross-linking, and hydrogen bonding can enhance stability.…”