Synthesis and characterization of Co(II)–Co(III) LDH and Ac@Co(II)–Co(III) LDH nanohybrid and study of its application as bactericidal agents

Abstract

The present study reports the green synthesis of a highly mesoporous Co(II)–Co(III) LDH and its nanohybrid through a sol–gel route with non-aqueous ethanol: acetone mixture as greener reagents. The compounds were characterized using PXRD, FESEM, HRTEM, FTIR, XPS, TGA-DTA, etc. It was observed that the synthesized Co(II)–Co(III) LDH and its nanohybrid showed well-organized LDH structures similar to that of the Mg-Al hydrotalcite material, bearing mesopores and crystalline structures highly as confirmed by PXRD, FESEM, and HRTEM studies.FTIR, XPS, and TGA-DTA studies also showed that the synthesized compounds formed a typical LDH –OH shared construction, containing di and trivalent cobalt with a 3:1 divalent: trivalent LDH ratio, and exhibited a common three-step thermal degradation behavior. Zeta potential and BET analysis showed that the synthesized materials bear a positive charge typical of LDH composition; the surface area and pore volume were found to be 88 m2.g−1and 1.37 cm3.g−1(cobalt LDH), and the intercalated nanohybrid as 169 m2.g−1 and 1.26 cm3/g, respectively.Furthermore, antibacterial evaluation studies using a well-diffusion method, broth serial dilution method (MIC/MBC), and time-kill efficacy test showed the synthesized compounds are effective bactericidal agents against the two bacterial strains viz S. aureus(gram-positive) and E.coli(gram-negative). The results showed that the synthesized Ac@Co(II)–Co(III) LDH nanohybrid showed better activity than Co(II)–Co(III) LDH. The inhibition activity of cobalt LDH and its nanohybrid were found to be higher against E.coli than S.aureus. This higher inhibition activity might be due to the factors like particle size, high surface area, and positively charged active cobalt LDH nanoparticles with acetylacetone molecule, which act on the negatively charged host cell membrane, resulting in the damage of bacterial cell wall.