*2.1. Materials*

Chitosan (CS), Tetraethoxysilane (TEOS) and Polyvinyl Alcohol (PVA) were purchased from Merck, Darmstadt, Germany. Graphite powder, NaCl, Na2HPO4, KH2PO4, KCl, NaOH, HCl, Acetic acid, Phosphoric acid, Sulphuric acid, Potassium Permanganate (KMnO4), Hydrogen peroxide (H2O2) and ethanol were purchased from Sigma-Aldrich, Burlington, Massachusetts, USA. Deionized water was used for the preparation of solutions and suspensions. Paracetamol was obtained from a local pharmaceutical company. Mouse pre-osteoblast (*MC3T3-E1*) cell lines were purchased from the American Type Culture Collection (ATCC-USA), and Hyclone Laboratories Inc, Logan, Utah, USA. supplied Alpha-MEM (α-MEM). The fetal bovine serum (*FBS*) and L-glutamine penicillin/streptomycin were obtained from ThermoFisher Scientific, Gloucester, United Kingdom.

#### *2.2. Experimental Details*
