Facile synthesis and characterization of Au nanoparticles-loaded kaolin mediated by Thymbra spicata extract and its application on bone regeneration in a rat calvaria defect model and screening system

Abstract The current work demonstrates the fabrication of kaolin supported Au nanoparticles (Au NPs-kaolin) mediated by Thymbra spicata extract as green reductant and capping agent without any toxic reagent. Physicochemical characteristics of the said nanocomposite were elucidated by field emission scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, elemental mapping, X-ray diffraction and inductively coupled plasma techniques. The figures of the TEM display the black dots signifying Au NPs being dispersed over the kaolin surface. Size of spherical Au NPs are around 10–15 nm. In the in vivo, we established a rat calvaria defect model using a combination of collagen scaffold and nanoparticle. The experimental group was divided into three classifications: control, collagen matrix and nanoparticle with collagen. Histological analyses showed that nanoparticle increased bone formation activity when used in conjunction with collagen matrix. In the nanoparticle group, grafted materials were still present until 12 weeks after treatment, as evidenced by foreign body reactions showing multinucleated giant cells in chronic inflammatory vascular connective tissue. Other results revealed that the nanoparticle increased bone formation activity when used with collagen matrix. All groups showed almost the same histological findings until 7 weeks. In the experimental groups, new bone formation activity was found continuously up to 12 weeks.