Calcified gelatin nanofibers for guided tissue regeneration using water-based benign solvent: An investigation for periodontal applications

Abstract

Periodontal regeneration, especially guided tissue regeneration (GTR), is one of the expanding applications in the field of tissue engineering. GTR barriers serve an exceptional function in healing various periodontal diseases such as gingivitis, periodontitis and loss of alveolar bone. Healing of periodontal pockets is somehow challenging as epithelial cells originated from the gingiva fill the site of defect and no regeneration takes place. Complete cell occlusion is a critical characteristic in case of pockets healing to obstruct gingival tissue growth, which performed via GTR membrane. Various materials were investigated for the synthesis of GTR membranes with collagen being the desired one among other bioresorbable polymers. Although collagen is renowned for its exquisite properties in mimicking the extracellular matrix (ECM), its high cost recalls for a substitute. In an attempt to introduce a new composite for GTR membrane, cost effective gelatin was mixed with calcium carbonate at different concentrations and electrospun using a benign solvent. Different concentrations of gelatin solutions were first investigated to obtain smooth fibers using diluted acetic acid, where 40% of gelatin solution was successively electrospun into smooth fibers with diameters ranging from 140-260nm. Experiments were carried out by adding calcium carbonate (CaCO3) at different concentrations. While smooth fibers were successfully obtained at lower concentrations of CaCO3, beaded broken fibers were obtained at higher concentrations. The diameter of the smooth nanofibers was found to increase with increasing the concentration of CaCO3. As gelatin is well known for its poor mechanical properties and stability, crosslinking using gluteraldhyde (GTA) vapors was considered to be a mandatory step. Different crosslinking time intervals were investigated for better stability, with the 20 h crosslinked mats showed enhanced water resistance and increased viability. Although the stability of nanofibers is elevated with prolonged crosslinking time, the pore size distribution among different mats was found to be almost the same (up to 250 nm) with the majority of the pores up to 50 nm. Crosslinked mats showed distinguished mass increase during both swelling and biodegradability tests, especially with the decrease of calcium concentration among the mats. The presence of calcium within the mats acts as a nucleation site for the growth of Ca-P structures, leading to mineralization of the mats. Not only calcified did gelatin mats show promising results in MTT assay but also overall improved functional and structural properties. In summary, calcified gelatin mats proved to be a good candidate for guided tissue regeneration.