Glycine-functionalized Fe3O4@TiO2:Er(3+),Yb(3+) nanocarrier for microwave-triggered controllable drug release and study on mechanism of loading/release process using microcalorimetry.

OBJECTIVES: The current study aimed at developing microwave-triggered controlled-release drug delivery systems using glycine-modified Fe3O4@TiO2:Er(3+),Yb(3+) multifunctional core-shell nanoparticles. We also studied the drug loading and release mechanisms by means of microcalorimetry. METHODS: We used hydrothermal method to prepare glycine-functionalized Fe3O4@TiO2:Er(3+),Yb(3+) multifunctional nanoparticles. The controlled release of the Fe3O4@TiO2:Er(3+),Yb(3+)-glycine-VP16 triggered by microwave was determined with ultraviolet-visible spectroscopic analysis. We studied the cytotoxicity of the nanocarrier by MTT assay. RESULTS: The thermodynamic parameter values (ΔH = -17.46 kJ mol(-1), ΔS = -365.20 kJ mol(-1)) showed that the main interaction between the carrier and drug molecules is hydrogen bonding. The molar enthalpy (ΔH) of the drug-release process was 72.01 kJ mol(-1), which indicates an endothermic process. This suggests that drug release can be controlled by microwave heating. The release profile can be controlled by the duration and number of cycles of microwave application. The particles also exhibit good magnetization and upconversion luminescence properties, which will allow simultaneous targeting and monitoring of the loaded drug. CONCLUSION: The modification of glycine and the introduction of absorbing material not only increased the load properties of the composite materials but also realized the microwave-stimulated anticancer drug controlled release.

A multifunctional ß-CD-modified Fe3O4@ZnO:Er(3+),Yb(3+) nanocarrier for antitumor drug delivery and microwave-triggered drug release.

We constructed a novel core-shell structured Fe3O4@ZnO:Er(3+),Yb(3+)@(ß-CD) nanoparticles used as drug carrier to investigate the loading and controllable release properties of the chemotherapeutic drug etoposide (VP-16). The cavity of ß-cyclodextrin is chemically inert, it can store etoposide molecules by means of hydrophobic interactions. The Fe3O4 core and ZnO:Er(3+),Yb(3+) shell functioned successfully for magnetic targeting and up-conversion fluorescence imaging, respectively. In addition, the ZnO:Er(3+),Yb(3+) shell acts as a good microwave absorber with excellent microwave thermal response property for microwave triggered drug release (the VP-16 release of 18% under microwave irradiation for 15 min outclass the 2% within 6h without microwave irradiation release). The release profile could be controlled by the duration and number of cycles of microwave application. This material therefore promises to be a useful noninvasive, externally controlled drug-delivery system in cancer therapy.