Mannose-modified ZnO particles for controlled Zn2+ release as potential drug carriers

In this study, ZnO particles of micro- and nanometer sizes were synthesized in a high-pressure reactor and modified with mannose for potential use as drug carriers in cancer therapy. The particles, confirmed as ZnO by XRD and FT-IR analyses, exhibited sizes ranging from 45 to 1834 nm, with optimal sizes of 20–800 nm suitable for passive transport through intercellular spaces in tumor tissues. Morphological analyses revealed nanorods and nanoflakes, with nanoflakes forming groove-like pores, as shown by BET isotherms. The zeta potential ranged from 14.2 to 27.9 mV, indicating a positive surface charge, favorable for interaction with negatively charged tumor cells. The mannose coating inhibited Zn²⁺ release, with the optimal mannose-to-ZnO molar ratio of 0.02 achieving Zn²⁺ concentrations as low as 1.92–2.35 mg/mL after one hour, significantly lower than the reference sample, which released 5.30 mg/mL at 30 min and 3.21 mg/mL at 60 min. A 2:1 ratio of precipitating agent to zinc precursor further minimized ion release and enhanced particle stability. Mannose proved to be an effective surface modifier due to its low cost, non-toxicity, biodegradability, and ability to improve the safety profile of the nanoparticles. These properties make the modified ZnO particles promising candidates for safe and efficient drug delivery systems in targeted cancer therapies.