To mimic the structure and composition of the natural bone extracellular matrix (ECM), fibrous hybrid scaffolds were prepared by electrospinning a solegel derived mixture of poly(gamma-glutamic acid) (gamma-PGA) and hydrolyzed tetraethylorthosilicate (TEOS). The introduction of NaHCO3 caused the formation of the sodium salt form of gamma-PGA, making the polymer soluble in aqueous-based solution. To improve the stability of electrospun gamma-PGA-silica hybrid scaffolds under physiological environment, 3-glycidoxypropyl trimethoxysilane (GPTMS) was employed as a coupling agent to link gamma-PGA and silanols of the hydrolyzed TEOS. The effect of the TEOS content on the physicochemical properties of the electrospun hybrid scaffolds, such as morphology, microstructure, mechanical behavior, degradation, as well as in vitro biocompatibility were investigated. The resultant fibers revealed a uniform morphology with the increased mean diameter as the content of TEOS increased. The results of FTIR and Si-29 MAS-NMR indicated that gamma-PGA and silica networks were successfully covalent-linked in the presence of GPTMS. All of these electrospun hybrid scaffolds showed stable soluble silica release without any initial burst release in Tris-HCl buffer solution and the content of released silicon can also be adjusted by the TEOS content. In addition, the tensile mechanical performances, thermal stability, and in vitro proliferation and ALP activity of fibrous scaffolds were effectively improved by the increasing TEOS content. The results suggest that the gamma-PGA-silica hybrid scaffolds with tailorable physiochemical properties can provide an excellent ECM for bone tissue regeneration. (C) 2016 Elsevier Ltd. All rights reserved.