Calcification, porous silicon

Ji et al. have adapted soft lithographic microcontact printing [69, 70] with specific etching procedures to produce patterned porous silicon substrates for the spatially-controlled deposition of calcium phosphate [71]. Calcification, confirmed... 

The term biocompatibility is defined as the ability of a material to perform with an appropriate host response in a specific situation" (Williams 2008). A biocompatible material can be inert, where it would not induce a host immune response and have little or no toxic properties. A biocompatible material can also be bioactive, initiating a controlled physiological response. For porous silicon, bioactive properties were initially suggested based on the observation that hydroxyapatite (HA) crystals grow on microporous silicon films. HA has implications for bone tissue implants and bone tissue engineering (Canham 1995). An extension of this work showed that an applied cathodic current was able to further promote calcification on the surface (Canham et al. 1996). More recently, Moxon et al. showed another example of bioactive porous silicon where the material promoted neuron viability when inserted into rat brains as a potential neuronal biosensor, whereas planar silicon showed significantly fewer viable neurons surrounding the implant site (Moxon et al. 2007). 

Anglin EJ, Cheng L, Freeman WR, Sailor MJ (2008) Porous silicon in drug delivery devices and materials. Adv Drug Deliv Rev 60(11) 1266-1277 Bowditch AP, Waters K, Gale H, Rice P, Scott EAM, Canham LT, Reeves CL, Loni A, Cox TI (1999) In-vivo assessment of tissue compatibility and calcification of bulk and porous silicon. Mat Res Soc Symp Proc 536 149-154... 

Canham LT (1997) Biomedical applications of porous silicon. In Canham LT (ed) Properties of porous silicon, vol 18, EMIS datareviews. Short Run Press, London, pp 12-22 Canham LT, Reeves CL (1996) Apatite nucleation on low porosity silicon in acellular simulated body fluids. In Cotell CM, Meyer AE, Gorbatkin SM, Grobe GL (eds) Thin films and surfaces for bioactivity and biomedical applications, vol 414, Materials research society symposium proceedings. Materials Research Society, Pittsburgh, pp 189-194 Canham LT, Newey JP, Reeves CL, Houlton MR, Loni A, Simmons AJ, Cox T1 (1996a) The effects of DC electric currents on the in-vitro calcification of bioactive Si wafers. Adv Mater 8(10) 847-849... 

Fan D, Akkaraju GR, Couch EF, Canham LT, Coffer JL (2011) The role of silicon in discriminating in vitro calcification for electrospun porous silicon-biopolymer orthopedic scaffolds. Nanoscale 3 354-361... 

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