Modification of bacterial cellulose with citric acid and its evaluation for potential application in bone tissue regeneration

Abstract

Bacterial cellulose (BC) is an advanced biocompatible polymeric biomaterial with a wide range of biomedical uses, including tissue engineering scaffolds and wound dressings. The main barriers to employing BC in tissue engineering (TE) were the collapse phenomena (the inability to reabsorb water after dehydration) and poor cell adhesion. This research focuses on modifying the nata-de-coco-based BC through thermal crosslinking with citric acid (CA) monohydrate in the absence of a catalyst as the first phase. This is to enhance the BC’s biomineralization ability and biocompatibility for application as a bone tissue scaffold. Morphological, physicochemical, and mechanical characterizations of the modified BC were done by means of scanning electron microscopy (SEM), attenuated total reflectance Fourier transformed infrared (ATR-FTIR) spectroscopy, x-ray diffraction (XRD), energydispersive x-ray (EDX), thermal gravimetric analysis (TGA), swelling rate (SR), water contact angle (WCA) and tensile analyses. The second phase of the work explored the hydroxyapatite (HA) biomineralization potential of the MBC via a biomimetic synthesis in simulated body fluid (SBF). Selected modified BC (MBC) samples were immersed in SBF and incubated at 37 °C in a water bath for 1, 7, 14, and 21 days. Biomineralized samples (BMBC) were freeze-dried and characterized by means of field emission scanning electron microscopy (FE-SEM), ATR-FTIR, XRD, TGA, and wet samples for compressive modulus. The third phase was the evaluation of the biological responses of the BMBC scaffolds to human fetal osteoblast cells. MTS (3- [4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) reagent and trypan blue dye were employed for cell viability and cytotoxicity while glutaraldehyde fixation was used to evaluate the cell attachment. The finding shows the emergence of ester bond associated FTIR peaks and additional crystalline XRD peaks on all MBC samples which were evidence of the CA crosslinking on the BC. The MBC samples have shown potential antibacterial activity against some bacterial species at certain concentrations based on the disc diffusion technique (DDT) and minimum inhibitory concentration (MIC) assays. Antioxidant activity evaluation has also revealed some radical atom scavenging activity of the MBC in 1-diphenyl-2-picrylhydrazyl (DPPH) solution. Samples showing the best HA nucleation were tested in vitro for cell viability, cytotoxicity, and attachment. Osteoblast cell proliferation and attachment on the BMBC samples after 3, 5 and 7 days of culture were the proof of its biocompatibility. Based on the in vitro study results presented here, it is apparent that the developed BMBC scaffold is bioactive and biocompatible; thus, it can be considered as a potential.