Mineralization of poly(L-lactic acid)-based foams induced by cellulose nanofibrils

Cellulose nanofibrils (CNFs) were blended with poly(L-lactic acid) (PLLA) to produce CNFs/PLLA composite solid foams. The dispersed CNFs' phase was partially embedded in the PLLA matrix. The CNFs not only reduced the water contact angle of the composite, but also induced the formation of hydroxyapatite (HA) on the walls of its inner pores. After incubation for 7 days in 3x simulated body fluid, a large number of HA particles were formed throughout the CNFs/PLLA composite foams. HA particles have diameters ranging from 200 nm to 2 mu m and a Ca/P ratio of 1.42. The spatial distribution of calcium and phosphorus elements was uniform. A porosity of approximately 92 % was achieved after mineralization of the CNFs/PLLA composite foams. The mass of HA grown over CNFs/PLLA foams increased faster than in the case of PLLA foams. The ternary polymeric foams have potential applications in tissue engineering.