TY - JOUR

T1 - Synthesis of bioactive class II poly(gamma-glutamic acid)/silica hybrids for bone regeneration

AU - Poologasundarampillai, Gowsihan

AU - Ionescu, Claudia

AU - Tsigkou, Olga

AU - Murugesan, Muthu

AU - Hill, Robert G.

AU - Stevens, Molly M.

AU - Hanna, John V.

AU - Smith, Mark E.

AU - Jones, Julian R.

PY - 2010

Y1 - 2010

N2 - Bone grafts are commonly used to regenerate bone in defect sites resulting from disease or trauma but there is clinical need for artificial materials that will be readily available and reduce pain and recovery time for the patient. Current artificial bone graft materials include bioactive ceramics and glasses, which are too brittle for bone defects that experience cyclic load. The synthesis of a new nanocomposite material is described that has the potential of being a tough off-the-shelf artificial bone graft that can regenerate a bone defect and have enough flexibility to press-fit into place. The poly(gamma-glutamic acid)/bioactive silica hybrid material with composition 40 wt% organic and 60 wt% bioactive inorganic (composition 70 mol% SiO2 and 30 mol% CaO) was synthesised using a sol-gel route. The potential advantage of a hybrid material over conventional composites is the molecular scale interactions between the bioactive inorganic and the tough degradable organic. The organic and inorganic chains were covalently cross-linked using an organosilane that has an organic functionality to bond to poly( g-glutamic acid) (gamma-PGA) and an alkoxysilane group that condenses with the inorganic phase. The covalent cross-linking (class II hybrid) is required to control the dissolution and improve mechanical properties of the material. The two key variables, the concentration of cross-linking agent and the addition of calcium, were investigated by Si-29 solid-state NMR and electron microscopy. The hybrid materials were bioactive in simulated body fluid (SBF) with a hydroxy carbonate apatite (HCA) layer detected after immersion for 72 h. The hybrid material favours cell attachment and is not cytotoxic as demonstrated by culture of the osteosarcoma cell line SaOs-2 on the material for 4 days.

AB - Bone grafts are commonly used to regenerate bone in defect sites resulting from disease or trauma but there is clinical need for artificial materials that will be readily available and reduce pain and recovery time for the patient. Current artificial bone graft materials include bioactive ceramics and glasses, which are too brittle for bone defects that experience cyclic load. The synthesis of a new nanocomposite material is described that has the potential of being a tough off-the-shelf artificial bone graft that can regenerate a bone defect and have enough flexibility to press-fit into place. The poly(gamma-glutamic acid)/bioactive silica hybrid material with composition 40 wt% organic and 60 wt% bioactive inorganic (composition 70 mol% SiO2 and 30 mol% CaO) was synthesised using a sol-gel route. The potential advantage of a hybrid material over conventional composites is the molecular scale interactions between the bioactive inorganic and the tough degradable organic. The organic and inorganic chains were covalently cross-linked using an organosilane that has an organic functionality to bond to poly( g-glutamic acid) (gamma-PGA) and an alkoxysilane group that condenses with the inorganic phase. The covalent cross-linking (class II hybrid) is required to control the dissolution and improve mechanical properties of the material. The two key variables, the concentration of cross-linking agent and the addition of calcium, were investigated by Si-29 solid-state NMR and electron microscopy. The hybrid materials were bioactive in simulated body fluid (SBF) with a hydroxy carbonate apatite (HCA) layer detected after immersion for 72 h. The hybrid material favours cell attachment and is not cytotoxic as demonstrated by culture of the osteosarcoma cell line SaOs-2 on the material for 4 days.

U2 - 10.1039/c0jm00930j

DO - 10.1039/c0jm00930j

M3 - Journal article

VL - 20

SP - 8952

EP - 8961

JO - Journal of Materials Chemistry

JF - Journal of Materials Chemistry

SN - 1364-5501

IS - 40

ER -