Hydroxyapatite–Mesoporous Silica Composites for Dual Quercetin Release and Encapsulation Efficiency

ABSTRACT Quercetin (QC) is a flavonoid with strong antioxidant and anti‐inflammatory properties, but its poor absorption and rapid metabolism significantly limit its bioavailability. Therefore, selecting an appropriate carrier material is critical for improving its loading and release performance. Recent studies have shown that hydroxyapatite/silica (HAP) composites exhibit higher bioactivity than pure HAP, while silica, a bioglass‐based material, is well tolerated by the human body. In this study, QC was loaded into HAP composites to investigate how different HAP ratios affect encapsulation efficiency, loading capacity, antioxidant activity, and release behavior in simulated gastric fluid (SGF, pH 1.2) and phosphate‐buffered saline (PBS, pH 7.4). Composites with HAP ratios of 1:1, 2:1, and 3:2 were synthesized and characterized by FTIR, XRD, SEM, and BET analyses to evaluate their structural, chemical, and surface properties. Among the formulations, HAP (2:1) showed the highest encapsulation efficiency (92%), while HAP (3:2) exhibited a more controlled release profile in PBS (59.1%). In contrast, HAP (1:1) showed the highest release under acidic conditions (98%). The DPPH assay confirmed that the QC ‐loaded composites retained antioxidant activity. Release data fit the Korsmeyer–Peppas model ( R ² > 0.98), indicating that both diffusion and matrix erosion governed drug release.