A study of the in-vitro bioactivity, dissolution and antibacterial activity of larnite prepared by a novel sol–gel combustion method using sucrose as a fuel

This article presents the preparation and antibacterial activity of larnite bioceramics, an active calcium silicate ceramic material having the molecular formula Ca2SiO4. A stepwise sol–gel combustion approach was used to prepare the single phasic larnite. The synthesis of larnite was carried out with calcium nitrate tetrahydrate as a source of calcium which acts as an oxidizing agent and tetraethyl orthosilicate as a source of silicate which acts as a reducing agent (fuel). The powders thus prepared were calcined at temperatures ranging from 400 to 800°C. X-ray diffraction analysis was used to study the phase formation and determine the hydroxyapatite (HAP) formation during the bioactivity studies. The synthesized materials were also characterized by Fourier-transform infrared, scanning electron microscopy and energy dispersive X-ray techniques. Elemental ionic concentration of the Ca, P and Si in stimulated body fluid (SBF) solution was analysed by inductively coupled plasma-optical emission spectroscopy. The bone-like apatite formation ability of larnite scaffolds was investigated by immersing it in SBF. It was observed that larnite has the capability to deposit HAP within the early stage of immersion. The antimicrobial activity of the larnite was screened against nine clinical pathogens. The fabricated larnite compound was tested against both Gram-positive bacteria (Staphylococcus aureus and Enterococcus sp.) and Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Serratia marcescens, Shigella sp., Proteus mirabilis, Salmonella sp. and Klebsiella pneumoniae) via the agar diffusion method. The obtained results suggested that the prepared larnite has a high antibacterial property against Gram-negative bacteria because of its thin peptidoglycan layer. From the overall results it is concluded that larnite could be a promising candidate for biomedical applications.