Biophysics Group, Department of Physics and Astronomy, University College London, Gower street, London WC1E 6BT, UK.
UCL Healthcare Biomagnetic and Nanomaterials Laboratories, 21 Albemarle street, London W1S 4BS, UK.
J Mater Chem B. 2023 Jan 25;11(4):787-801. doi: 10.1039/d2tb01338j.
Magnetic nanoparticles (NPs) are powerful agents to induce hyperthermia in tumours upon the application of an alternating magnetic field or an infrared laser. Dopants have been investigated to alter different properties of materials. Herein, the effect of zinc doping into iron oxide NPs on their magnetic properties and structural characteristics has been investigated in-depth. A high temperature reaction with autogenous pressure was used to prepare iron oxide and zinc ferrite NPs of same size and morphology for direct comparison. Pressure was key in obtaining high quality nanocrystals with reduced lattice strain (27% less) and enhanced magnetic properties. ZnFeO NPs with small size of 10.2 ± 2.5 nm and very high saturation magnetisation of 142 ± 9 emu g were obtained. Aqueous dispersion of the NPs showed long term magnetic (up to 24 months) and colloidal stability (at least 6 d) at physiologically mimicking conditions. The samples had been kept in the fridge and had been stable for four years. The biocompatibility of ZnFeO NPs was next evaluated by metabolic activity, membrane integrity and clonogenic assays, which show an equivalence to that of iron oxide NPs. Zinc doping decreased the bandgap of the material by 22% making it a more efficient photothermal agent than iron oxide-based ones. Semiconductor photo-hyperthermia was shown to outperform magneto-hyperthermia in cancer cells, reaching the same temperature 17 times faster whilst using 20 times less material (20 mg ml. 1 mg ml). Magnetothermal conversion was minimally hindered in the cellular confinement whilst photothermal efficiency remained unchanged. Photothermia treatment alone achieved 100% cell death after 10 min of treatment compared to only 30% cell death achieved with magnetothermia at clinically relevant settings for each at their best performing concentration. Altogether, these results suggest that the biocompatible and superparamagnetic zinc ferrite NPs could be a next biomaterial of choice for photo-hyperthermia, which could outperform current iron oxide NPs for magnetic hyperthermia.
磁性纳米粒子（NPs）是在应用交变磁场或红外激光时在肿瘤中诱导热疗的有效试剂。掺杂剂已被研究用于改变材料的不同性质。在此，深入研究了锌掺杂进入氧化铁 NPs 对其磁性和结构特性的影响。使用高温自生压力反应来制备具有相同尺寸和形态的氧化铁和锌铁氧体 NPs，以便直接进行比较。压力是获得具有低晶格应变（低 27%）和增强磁性的高质量纳米晶体的关键。获得了尺寸为 10.2 ± 2.5nm 且具有非常高饱和磁化强度（142 ± 9emu/g）的小尺寸 ZnFeO NPs。在生理模拟条件下，NP 的水性分散体显示出长期磁性（长达 24 个月）和胶体稳定性（至少 6d）。在冰箱中保存样品 4 年后，其仍稳定。接下来通过代谢活性、膜完整性和集落形成测定评估了 ZnFeO NPs 的生物相容性，结果表明其与氧化铁 NPs 相当。锌掺杂使材料的带隙降低了 22%，使其比基于氧化铁的材料更有效地作为光热试剂。在癌细胞中，半导体光热疗法比磁热疗法表现更好，达到相同温度的速度快 17 倍，而使用的材料少 20 倍（20mg/ml 比 1mg/ml）。在细胞限制中，磁热转换受到的阻碍最小，而光热效率保持不变。单独的光热治疗在 10 分钟的治疗后即可实现 100%的细胞死亡，而在临床相关设置下，磁热治疗仅达到 30%的细胞死亡，在每种情况下，最佳浓度下的细胞死亡率均为 30%。总的来说，这些结果表明，生物相容的超顺磁性锌铁氧体 NPs 可能成为光热疗法的下一个生物材料选择，在磁热疗法方面，其性能优于当前的氧化铁 NPs。
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