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In the human body, tissues are mainly composed of a nano-fibrous structure of collagen which makes up part of the extra cellular matrix (ECM). There are many structural proteins that compose the organic matrix, but collagen corresponds to 90% of the total protein content in bone ECM. Of the different types of collagen, the most abundant in bone tissue is type I collagen. Its mineral phase, which represents 70%–90% of the bone, is primarily composed of hydroxyapatite. Electrospinning is an attractive method for the generation of polymeric nano-fibrous mats to be used for applications in biomedical engineering and tissue regeneration. It offers the capacity of emulating the morphological characteristics of tissue matrix in geometry, chemistry, mechanical properties, orientation and scale. Since the ECM of bone is composed of an organic phase, composed of elastic proteins that provide fracture resistance and a mineral phase composed of inorganic mineral which contributes to the rigidity in bones; it is ideal to prepare a collagen/hydroxyapatite (COL/HA) electrospun scaffold for bone tissue engineering applications. The fabrication of electrospun bone tissue scaffolds that mimics the extracellular matrix of bones have been confined to the use of toxic solvents such as trifluoroacetic acid, and 1,1,1,3,3,3,-hexafluoro-2-propanol in its preparation, thus have been limited. These toxic solvents limit or reduce the potential use of the scaffold in biomedical applications. In our work, a nano-fibrous collagen/hydroxyapatite scaffold was prepared by electrospinning using a mild solvent. To accomplish this, hydroxyapatite was dispersed into a collagen/acetic acid/water solution, which was later electrospun to generate composite nanofibers. Furthermore, electron microscopy revealed that it is possible to modulate the fiber diameter, porosity and fiber alignment by varying the supplied voltage, volumetric flow rate, the RPMs of the motor and Hydroxyapatite concentration. The versatility of this technique allows for the fine-tuning of the final properties of the scaffold by controlling the different operational variables. Moreover, both X-ray and infrared spectroscopy confirm the presence of the hydroxyapatite embedded in the collagen fibers or adhered to the surface of the fiber. This phenomenon was observed to be dependent on the diameter of the particle. Additionally, the inclusion of hydroxyapatite does not alter the native collagen structure. Lastly, in vitro studies showed these composite nanofibers support pre-osteoblast adhesion, which indicates that this non-toxic or “green” electrospun ECM mimetic structure of bone tissue could be used to generate nanocomposite scaffolds with potential biomedical applications such as tissue regeneration

Keywords: electrospinning, collagen, Hydroxyapatite