Facile synthesis of fluorescent mesoporous nanocarriers with pH-sensitive controlled release of naturally derived dieckol

Abstract

Dieckol is a marine polyphenol found in the brown algae Ecklonia cava and has been actively studied because it has various biological activities such as antioxidant, anti-inflammatory, and antibacterial. Herein, fluorescent mesoporous silica nanoparticles (FMSNs) were synthesized for the efficient delivery of naturally derived Die molecules. The Die-loaded FMSNs (FMSNs-Die) were further coated with polyethylene glycol (PEG) and gra-phene oxide (GO) nanosheets, termed as FMSNs-Die@PEG and FMSNs-Die@PEG@GO, respectively. The release kinetics was investigated using Fickian-type exponential and Kosmeyer-Peppas relaxation models. Overall, the FMSN-based nanocarriers exhibited a faster release at pH 4.5 than at pH 7.4. The release rate at pH 7.4 decreased in the following order: FMSNs-Die > FMSNs-Die@PEG > FMSNs-Die@PEG@GO. In contrast, the release rate at pH 4.5 exhibited a somewhat different order of FMSNs-Die@PEG >= FMSNs-Die > FMSNs-Die@PEG@GO. Notably, the difference of the release rates at these pH values was most pronounced for the PEG-coated FMSNs, signifying the strong pH-responsive release behavior of Die molecules. Within the pH ranges (pH 4.5 - 7.4), double-layer-coated FMSNs exhibited the significantly delayed release rates as compared to coating-free and single-layer-coated analogs. Our nanocarriers demonstrated pH-sensitive controlled release of Die, suggesting as a smart drug delivery system for natural product-derived drugs.