Synthesis and characterization of an eco-friendly nano-hybrid based on luteolin-loaded zinc-aluminum layered double hydroxide for biological applications

Abstract

A newly developed bio-hybrid material comprising luteolin as a bioactive dye and a Zinc-Aluminum layered double hydroxide as an adsorbent was synthesized using two distinct methods. In the first method, Zinc-Aluminum layered double hydroxide was initially produced using the co-precipitation technique. Subsequently, the bioactive luteolin was intercalated onto the synthesized layered double hydroxide through an ion exchange mechanism. Response surface methodology and analysis of variance studies were employed to design experiments leading to achieve optimized adsorption onto the Zinc-Aluminum layered double hydroxide, considering effective variables like pH, dye concentration, layered double hydroxide weight, and operating time. Under the optimized conditions, the maximum adsorption efficiency (94.2%) and adsorption capacity (47.11 mg g⁻¹) were achieved. Kinetic studies indicated the pseudo-second order model characterized the luteolin adsorption, and the Langmuir model served as a suitable representation of the adsorption isotherm. In the second method, a co-precipitation approach was employed to simultaneously synthesize and intercalate luteolin onto layered double hydroxide with varying concentrations (5%, 15%, and 25%) under optimized conditions. The maximum adsorption efficiency and capacity reached 99.9% and 49.98 mg g⁻¹, respectively. Analytical characterization confirmed successful luteolin adsorption and stabilization of the layered double hydroxide. Furthermore, sustained luteolin release over an extended period was observed which attributed to its incorporation within the layered double hydroxide structure. The study also investigated the antioxidant activity of luteolin on the synthesized complexes, providing a comprehensive exploration of the bio-hybrid structure, Luteolin-Zinc-Aluminum Layered Double Hydroxide, with potential biomedical applications.