Tuning PEG-DA hydrogel properties via solvent-induced phase separation (SIPS)()

Abstract

Poly(ethylene glycol) diacrylate (PEG-DA) hydrogels are widely utilized to probe cell-material interactions and ultimately for a material-guided approach to tissue regeneration. In this study, PEG-DA hydrogels were fabricated via solvent-induced phase separation (SIPS) to obtain hydrogels with a broader range of tunable physical properties including morphology (e.g. porosity), swelling and modulus (G'). In contrast to conventional PEG-DA hydrogels prepared from an aqueous precursor solution, the reported SIPS protocol utilized a dichloromethane (DCM) precursor solution which was sequentially photopolymerized, dried and hydrated. Physical properties were further tailored by varying the PEG-DA wt% concentration (5 wt%-25 wt%) and M(n) (3.4k and 6k g mol (-1)). SIPS produced PEG-DA hydrogels with a macroporous morphology as well as increased G' values versus the corresponding conventional PEG-DA hydrogels. Notably, since the total swelling was not significantly changed versus the corresponding conventional PEG-DA hydrogels, pairs or series of hydrogels represent scaffolds in which morphology and hydration or G' and hydration are uncoupled. In addition, PEG-DA hydrogels prepared via SIPS exhibited enhanced degradation rates.

Fig. 1

Macroscopic images of conventional PEG-DA hydrogels fabricated from an aqueous precursor solution [left] and PEG-DA hydrogels fabricated via SIPS with a DCM precursor solution (and subsequently dried and hydrated) [right]. Inset top view of each corresponding ⁻¹; 10 wt% concentration). hydrogel. (PEG-DA: M_n = 6k g mol

Fig. 2

SEM images of PEG-DA hydrogels fabricated via SIPS (scale bars = 100 μm).

Fig. 3

Swelling ratio of PEG-DA hydrogels fabricated with 3.4k g mol⁻¹ (left) and 6k g mol⁻¹ (right) PEG-DA from a DCM precursor solution (i.e. via SIPS) or from an aqueous precursor solution. Statistical significance was determined by student’s t-test where (*): p < 0.05 and (#): p > 0.05.

Fig. 4

Storage modulus (G′) of PEG-DA hydrogels fabricated with 3.4k g mol⁻¹ (left) and 6k g mol⁻¹ (right) PEG-DA from a DCM precursor solution (i.e. via SIPS) [solid lines] or from an aqueous precursor solution [dashed lines].

Fig. 5

Swelling ratio as a function of degradation time under basic conditions (0.05 M NaOH) of PEG-DA hydrogels fabricated with 3.4k g mol⁻¹ (left) and PEG-DA 6k g mol⁻¹ (right) via SIPS at various wt% concentrations. [] = hours to complete dissolution. () = hours to complete dissolution for analogous conventional hydrogels (i.e. prepared from aqueous precursor solutions).