Eremin Yuri, Lopushenko Vladimir
Department of Computational Mathematics and Cybernetics, Moscow Lomonosov State University, 119991 Moscow, Russia.
Nanomaterials (Basel). 2021 Dec 4;11(12):3297. doi: 10.3390/nano11123297.
Magnetoplasmonics based on composite nanostructures is widely used in many biomedical applications. Nanostructures, consisting of a magnetic core and a gold shell, exhibit plasmonic properties, that allow the concentration of electromagnetic energy in ultra-small volumes when used, for example, in imaging and therapy. Magnetoplasmonic nanostructures have become an indispensable tool in nanomedicine. The gold shell protects the core from oxidation and corrosion, providing a biocompatible platform for tumor imaging and cancer treatment. By adjusting the size of the core and the shell thickness, the maximum energy concentration can be shifted from the ultraviolet to the near infrared, where the depth of light penetration is maximum due to low scattering and absorption by tissues. A decrease in the thickness of the gold shell to several nanometers leads to the appearance of the quantum effect of spatial dispersion in the metal. The presence of the quantum effect can cause both a significant decrease in the level of energy concentration by plasmon particles and a shift of the maxima to the short-wavelength region, thereby reducing the expected therapeutic effect. In this study, to describe the influence of the quantum effect of spatial dispersion, we used the discrete sources method, which incorporates the generalized non-local optical response theory. This approach made it possible to account for the influence of the nonlocal effect on the optical properties of composite nanoparticles, including the impact of the asymmetry of the core-shell structure on the energy characteristics. It was found that taking spatial dispersion into account leads to a decrease in the maximum value of the concentration of electromagnetic energy up to 25%, while the blue shift can reach 15 nm.
基于复合纳米结构的磁等离子体激元学在许多生物医学应用中得到了广泛应用。由磁芯和金壳组成的纳米结构具有等离子体激元特性，例如在成像和治疗中使用时，可使电磁能量集中在超小体积内。磁等离子体激元纳米结构已成为纳米医学中不可或缺的工具。金壳可保护磁芯免受氧化和腐蚀，为肿瘤成像和癌症治疗提供生物相容性平台。通过调整磁芯尺寸和壳厚度，最大能量集中可从紫外线转移到近红外，由于组织的低散射和吸收，近红外光的穿透深度最大。金壳厚度减小到几纳米会导致金属中出现空间色散的量子效应。量子效应的存在既会导致等离子体激元粒子的能量集中水平显著降低，又会使最大值向短波长区域移动，从而降低预期的治疗效果。在本研究中，为了描述空间色散量子效应的影响，我们使用了离散源方法，该方法纳入了广义非局部光学响应理论。这种方法能够考虑非局部效应对复合纳米粒子光学性质的影响，包括核壳结构不对称对能量特性的影响。研究发现，考虑空间色散会导致电磁能量集中的最大值降低25%，而蓝移可达15纳米。
