Preparation and evaluation of hydroxyapatite - gelatin - curcumin nanocomposites and testing their antimicrobial effects on Escherichia coli, Staphylococcus aureus and Streptococcus mutans

Abstract

Introduction: Composites can be used in a variety of applications in dentistry. Recently, nanocomposites have obtained a special place in dentistry. They can be used as fillers, repair materials, tissue engineering materials and drug delivery systems (composites containing drugs) for oral diseases. Fiber nanocomposites, in addition to possess all the properties of composites, have a high surface-to-volume ratio due to their fiber nature. In this study, we prepared and evaluated hydroxyapatite-gelatin-curcumin fiber nanocomposites and determined their antimicrobial effects against Escherichia coli, Staphylococcus aureus and Streptococcus mutans. Materials and Methods: Hydroxyapatite-gelatin-curcumin fiber nanocomposites were prepared by electrospinning method. The prepared nanocomposites were then subjected to physicochemical studies. The light scattering method to determine particle size, Fourier transmission infrared spectroscopy (FTIR) to investigate possible bonds and to identify functional groups, X-ray diffraction to study crystallinity. Scanning electron microscopy (SEM, TESCAN, Warrendale, PA) was used to study the morphology. For microbial evaluation of nanocomposites containing curcumin, disk diffusion method was used against Streptococcus mutans, Staphylococcus aureus, Escherichia coli and after 24 hours of incubation at 35 ° C, the plates were examined for diameter of growth inhibition zone. Results were reported as an average of three measurements (mean ± standard deviation). Shapiro-Wilk test was used to evaluate the normality of the data. One-way analysis of variance was used to compare the mean results of growth inhibition zone between bacteria. Graph Pad version 9 software was used for data analysis. The probability value was considered less than 0.05. Results: The results of electron microscope morphological evaluations showed that the nanofibers were uniformly formed in the shape of lattice nanometer fibers. The prepared nanofibers according to the obtained images did not have bead (structural defect). The release pattern of curcumin from nanocomposite was a two-stage release, 60% of which released in the first two days and the rest slowly until the 14th day. No new interactions were observed in the FTIR and XRD spectra of the studied materials. The results of microbial evaluations showed that the order for the growth inhibition zone was Escherichia coli, Streptococcus mutans and Staphylococcus aureus, respectively. The difference in the amount of growth inhibition zone between bacteria was significant for the prepared nanocomposite (P = 0.0086). Conclusion: In this study, suitable physicochemical results were obtained for gelatin-hydroxyapatite-curcumin nanocomposites. It seems that the use of these nanocomposites in the optimal formulation can be used in the manufacture of various scaffolds in dental tissue engineering or for use in mixtures of dental fillings or restorative materials. Also, according to the appropriate microbial results, in the future, the use of plant materials can be used instead of chemical antimicrobials or along with them to reduce bacterial resistance. Then, the physico-mechanical tests need to be performed on the prepared nanocomposite material. Cellular tests are also recommended to investigate the effects of hydroxyapatite nanoparticles on inducing bone tissue growth or other properties. The effects of growth induction and tissue repair related to curcumin can also be investigated in vitro on cells. Extensive animal and clinical studies are also needed to prove the true and clinical function of this new substance.