Biomimetic apatite deposition on polymeric microspheres treated with a calcium silicate solution

Bioactive polymeric microspheres can be prepared by means of coating them with a calcium silicate solution and subsequently soaking in a simulated body fluid (SBF). Such combination should allow for the development of bioactive microspheres for several applications in the medical field including tissue engineering carriers. Four types of polymeric microspheres, with different sizes, were used in this work: (i) ethylene-vinyl alcohol copolymer (20-30 mum), (ii) polyamide 12 with 10% magnetite (100 mum), (iii) polyamide 12 (10-30 mum) and (iv) polyamide 12 (300 mum). These microspheres were soaked in a calcium silicate solution at 36.5 degrees C for various periods of time under different conditions. Afterwards, they were dried in air at 60 and 100 degrees C for 24 hr. Then, the samples were soaked in SBF for 1, 3, and 7 days. Fourier transformed infrared spectroscopy, thin-film X-ray diffraction, and scanning electron microscopy showed that after the calcium silicate treatment and the subsequent soaking in SBF, the microspheres successfully formed an apatite layer on their surfaces in SBF within 7 days due to the formation of silanol groups, which are effective for apatite formation.