BioglassR was the first synthetic material capable of bonding with bone without fibrous encapsulation, and fulfils some of the criteria of an ideal synthetic bone graft. However, it is brittle and toughness is required. Here, we investigated hybrids consisting of co-networks of high crosslinking density polymethacrylate and silica (class II hybrid) as a potential new generation of scaffold materials. Poly(3-(methoxysilyl)propyl methacrylate) (pTMSPMA) and tetraethyl orthosilicate (TEOS) were used as sol-gel precursors and hybrids were synthesised with different inorganic to organic ratios (I h ). The hybrids were nanoporous, with a modal pore diameter of 1 nm. At I h = 50 %, the release of silica was controlled by varying the molecular weight of pTMSPMA while retaining a specific surface area above 100 m 2 g −1 . Strain to failure increased to 14.2 %, for I h = 50 % using a polymer of 30 kDa, compared to 4.5 % for pure glass. The modulus of toughness (U T ) increased from 0.73 (pure glass) to 2.64 GPa. Although, the hybrid synthesised in this report did not contain calcium, pTMSPMA/SiO 2 hybrid was found to nucleate bone-like mineral on its surface after 1 week of immersion in simulated body fluid (SBF), whereas pure silica sol-gel glass did not. This increase in apatite forming ability was due to the ion-dipole complexation of calcium with the ester moieties of the polymer that were exposed after release of soluble silica from TEOS. No adverse cytotoxicity for MC3T3-E1 osteoblast-like cells was detected and improved cell attachment was observed, compared to a pure silica gel. pTMSPMA/SiO 2 hybrids have potential for the regeneration of hard tissue as they overcome the major drawbacks of pure inorganic substrates while retaining cell attachment.Bone is the second most transplanted tissue after blood and musculoskeletal pathology treatments represent £10 billion per year in the U.K. alone. 1,2 Effective alternatives must be found to the current methods of skeletal defect treatments to avoid postoperation infection or revision, which can cost up to £70,000 per patient. 3 One attractive approach is to design biodegradable implants that could actively promote the bone growth and tissue remodelling by stimulating cellular activities whilst providing a mechanical support to the tissue. 4 Bioglass R (BG), a biodegradable bioactive silicate glass (46.1 mol % SiO 2 , 26.9 mol % CaO, 24.2 mol % Na 2 O, 2.6 mol % P 2 O 5 ), was the first material capable of bonding with bone by the formation of an apatite layer that forms on its surface after grafting. 5 A second mode of action is its dissolution products (in particular silica), which enhance osteoblast activities, whilst promoting extra- * Corresponding author, E-mail: julian.r.jones@imperial.ac cellular matrix (ECM) production and cells differentiation. 6-8 3D scaffolds have been produced from bioactive glasses, with interconnected pore networks in the form of foams 9,10 or 3-D printed structures 11 , which can take load in compression, up to 150 MPa when 3D printed. 12 ...