A functional SiO2-TiO2 mesoporous assembly designed for the controlled release of carvacrol

Abstract

Mesoporous composites can be useful for the gentle release of biocides and fertilizers. Here, we study the structural, morphological, and drug-delivery advantages of SiO2-TiO2 (PST) particles synthesized by a hydrothermal method. The PST particles had a spherical-like assembly architecture, which was obtained by cobalt ions incorporation. Each assembly contains nanobars with acute or obtuse tip shape, notably in the sample with 0.5 wt% of Co. Drug loading/delivery evaluations were carried out using carvacrol (CVC) as biocidal molecule. PST composites functionalized with the triethanolamine presented higher load efficiencies of 30–37% and load capacities of 20–26%. A similar trend occurred for the release percentage of CVC. The PST samples without functionalization had a release of only 19–29% (at pH=7.4). After the TEOA functionalization, the release percentage was enhanced to 64–78%. Moreover, the PST had a maximum release percentage of 64.8% reached after only 3 min (at pH=7.4). In contrast, the PST doped with 1 wt% of Co reached the maximum release percentage of 64.8% after 24 h at pH=7.4. Hence, the results of this investigation demonstrate that the PST synthetized with Co and functionalized with TEOA could be used for the control of undesired weed and phytopathogens in cultivated plants by prolonging their delivery time of biocidal molecules.