Investigation of pure and Sn-doped Ca(OH)2 nanoparticles for optical and biomedical applications

Abstract

The present study explores the synthesis and characterization of pure and Sn-doped Ca(OH)2 nanoparticles, highlighting their potential for optical and biomedical applications. The incorporation of Sn into the Ca(OH)2 matrix is investigated for the first time, providing insights into its impact on the structural, optical, and biological properties of the nanoparticles. A straightforward precipitation method was employed to synthesize pure and Sn-doped calcium hydroxide nanoparticles. The synthesized nanoparticles were characterized by using X-ray diffraction (XRD) pattern, ultraviolet–visible–near infrared (UV-Vis-NIR) spectra, Fourier Scanning Electron Microscope (FESEM) micrographs, and agar well diffusion method for antibacterial study. X-ray diffraction examinations confirmed the polycrystalline nature of the Ca(OH)2 nanoparticles and revealed the structure to be hexagonal. The average crystallite size of the pure and Sn-doped Ca(OH)2 nanoparticles are 49 nm and 66 nm, respectively. The FESEM images of the sample revealed the formation of pure Ca(OH)2 nanoparticles in the form of nanoflakes and the change in the morphology while doping Sn with Ca(OH)2. The prepared samples were assessed using UV-Vis-NIR spectra, showing the UV absorption band at approximately 247 and 263 nm for the samples of pure and Sn-doped Ca(OH)2 nanoparticles, respectively. The calculated direct and indirect allowed band gap energies were found to be 4.04 and 3.92 eV for pure Ca(OH)2, and 3.37 and 2.94 eV in the case of Sn-doped Ca(OH)2. The antibacterial effectiveness of Ca(OH)2 nanoparticles was assessed using the well diffusion method, and it was observed that both the samples of pure and Sn doped Ca(OH)2 nanoparticles exhibited significant antibacterial properties against gram-negative bacterial strains. An elevation in Minimum Inhibitory Concentration (MIC) values for Sn-doped Ca(OH)2 nanoparticles compared to pure Ca(OH)2 nanoparticles was observed when examining their impact on Gram-negative bacteria (Klebsiella pneumoniae), which suggested a requirement for a higher concentration due to the nature of surface charges present in order to inhibit the growth of microorganisms.