A comparative study on surface/interface mechanism and antibacterial properties of different hybrid materials prepared with essential oils active ingredients and palygorskite

Six active ingredients of essential oils were chosen to prepare organic/inorganic antibacterial hybrid materials based on natural palygorskite by mechanical grinding. Fourier transform infrared spectroscopy, X-ray diffraction and Thermo gravimetric analysis were employed to comparatively study the stability of different organic/ inorganic hybrid materials, and the density functional theory calculation revealed that the key factor for formation of the stable hybrid materials was ascribed to the hydrogen bond between the oxygen-containing group of the essential oils ingredients and the Si-OH and Mg-OH2 groups of palygorskite. The minimum inhibitory concentration value against Escherichia coli and Staphylococci aureus was measured to test the antibacterial activity of hybrid materials. It was found that thymol/palygorskite hybrid materials exhibited the best antibacterial activity with the minimum inhibitory concentration values of 2.0 mg/mL, which was equal to that of carvacrol/palygorskite due to the similar molecular structures of thymol and carvacrol. Furthermore, the cymene/palygorskite, limonene/palygorskite and terpinene/palygorskite hybrid materials show a better bioavailability than their corresponding essential oils ingredients due to the increase in their hydrophilia and dispersion in aqueous solution. Based on the understanding on the surface/interface mechanism of essential oils ingredients and palygorskite, it is expected to guide the preparation of stable green antibacterial materials with excellent antibacterial activity combining with natural palygorskite and essential oils ingredients.

Automated summary

Six active ingredients of essential oils were chosen to prepare organic/inorganic antibacterial hybrid materials based on natural palygorskite by mechanical grinding. The stability of hybrid materials was studied using various analyses, and it was found that hydrogen bonding played a key role in their formation. The antibacterial activity and bioavailability of the hybrid materials were found to be related to their molecular structures and hydrophilicity.