Optimised encapsulation of repurposed gliclazide in nZIF-8 with pH-triggered drug release under tumour-mimicking conditions

The limited selectivity and systemic toxicity associated with conventional chemotherapy highlight the need for improved delivery strategies. In this study, a pH-responsive nano zeolitic imidazolate framework-8 (nZIF-8) system loaded with repurposed gliclazide (GLI) was synthesised at concentrations of 5, 10, and 15 mg/mL using a one-pot solvothermal method. PXRD analysis confirmed preservation of the ZIF-8 crystalline structure after drug incorporation. FTIR spectra indicated interactions between GLI and the framework. BET analysis showed a decrease in surface area and pore volume, particularly at 10 mg/mL, suggesting effective pore occupation. DLS measurements confirmed nanoscale particle size, and SEM analysis demonstrated maintained morphology after loading. Drug release studies showed enhanced GLI release at pH 5.5 compared to pH 7.4, consistent with the acid-sensitive behaviour of nZIF-8. Kinetic modelling of the release data indicated that the Higuchi model provided the highest correlation, suggesting diffusion-controlled release. These results indicate that nZIF-8@GLI is a stable and pH-responsive carrier system suitable for controlled delivery of repurposed drugs.