Degradation behaviors of biodegradable macroporous scaffolds prepared by gas foaming of effervescent salts

Biodegradable polymeric scaffolds for tissue engineering were fabricated by a gas-foaming/salt-leaching method using a combination of two effervescent salts, ammonium bicarbonate and citric acid. Poly(D,L-lactic-co-glycolic a cid) (PLGA) in a state of gel-like paste was first produced by precipitatio n of PLGA dissolved in chloroform into ethanol. The polymer slurry was mixe d with sieved particles of ammonium bicarbonate, molded, and then immersed in an aqueous solution of citric acid to generate macroporous scaffolds. Th e scaffolds had relatively homogeneous pore structures throughout the matri x and showed an average pore size of 200 mum and over 90% porosity. By adju sting the concentration of citric acid in the aqueous medium, it was possib le to control porosity as well as mechanical strength of the scaffolds. In vitro degradation studies of three different scaffolds having lactic/glycol ic acid molar ratios of 75/25, 65/35, and 50/50 exhibited marked swelling b ehaviors at different critical time points. The swollen matrices had a hydr ogel-like internal structure. It was found that massive water uptake into t he degrading scaffolds induced matrix swelling, which facilitated the hydro lytic scission of PLGA chains with concomitant disintegration of the matric es. (C) 2001 John Wiley & Sons, Inc.