Mansouri Elham, Rajabpour Saeed, Mesbahi Asghar
Student Research Committee, Tabriz University of Medical Sciences, Tabriz, Iran.
Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
BMC Chem. 2024 Oct 22;18(1):206. doi: 10.1186/s13065-024-01322-z.
Nanoparticles (NPs) as radiosensitizers present a promising strategy for enhancing radiotherapy effectiveness, but their potential is significantly influenced by the properties of their surface coating, which can impact treatment outcomes. Most Monte Carlo studies have focused on metallic NPs without considering the impact of coating layers on radiosensitization. In this study, we aim to assess both the physical and radiobiological effects of nanoparticle coatings in nanoparticle-based radiation therapy.
In this simulation study, we used Geant4 Monte Carlo (MC) toolkit (v10.07.p02) and simulated the bismuth, gold, iridium and gadolinium NPs coated with polyethylene glycol (PEG-400: Density: 1.13 g/cm³, Molar mass: 380-420 g/mol) as radiosensitizer for photon beams of 30, 60 and 100 keV. Secondary electron number and reactive oxygen species enhancement factor were estimated. Also, dose enhancement factor (DEF) was determined in spherical shells with logarithmic scale thickness from the nanoparticle surface to 4 mm.
Secondary electron emission was highest at 30 keV for gold, bismuth, and iridium NPs, while gadolinium NPs peaked at 60 keV. Coating reduced electron emissions across all energies, with thicker coatings leading to a more significant decrease. DEF values declined with increasing radial distance from the NP surface and were lower with thicker coatings. For gadolinium NPs, DEF behavior differed due to K-edge energy effects. Reactive species generation varied, showing maximum production at 30 keV for gold, bismuth, and iridium NPs, while gadolinium NPs showed peak activity at 60 keV. PEG coatings enhanced reactive species formation at 100 keV.
The findings indicate that the coating layer thickness and material not only influence the emission of secondary particles and DEF but also affect the generation of reactive species from water radiolysis. Specifically, thicker coatings reduce secondary particle emission and DEF, while PEG coatings demonstrate a dual behavior, offering both protective and enhancing effects depending on photon energy. These insights underscore the importance of optimizing NP design and coating in future studies to maximize therapeutic efficacy in nanoparticle-based radiation therapy.
纳米粒子（NPs）作为放射增敏剂是提高放射治疗效果的一种有前景的策略，但其潜力受表面涂层性质的显著影响，而表面涂层会影响治疗结果。大多数蒙特卡罗研究都集中在金属纳米粒子上，未考虑涂层对放射增敏的影响。在本研究中，我们旨在评估纳米粒子涂层在基于纳米粒子的放射治疗中的物理和放射生物学效应。
在本模拟研究中，我们使用Geant4蒙特卡罗（MC）工具包（v10.07.p02），模拟了涂有聚乙二醇（PEG - 400：密度：1.13 g/cm³，摩尔质量：380 - 420 g/mol）的铋、金、铱和钆纳米粒子作为30、60和100 keV光子束的放射增敏剂。估计了二次电子数和活性氧增强因子。此外，在从纳米粒子表面到4 mm的对数尺度厚度的球壳中确定了剂量增强因子（DEF）。
金、铋和铱纳米粒子的二次电子发射在30 keV时最高，而钆纳米粒子在60 keV时达到峰值。涂层降低了所有能量下的电子发射，涂层越厚，下降越显著。DEF值随着距纳米粒子表面径向距离的增加而下降，且涂层越厚，DEF值越低。对于钆纳米粒子，由于K边能量效应，DEF行为有所不同。活性物种的产生各不相同，金、铋和铱纳米粒子在30 keV时产生量最大，而钆纳米粒子在60 keV时活性最高。PEG涂层在100 keV时增强了活性物种的形成。
研究结果表明，涂层厚度和材料不仅影响二次粒子发射和DEF，还影响水辐射分解产生的活性物种。具体而言，较厚的涂层会减少二次粒子发射和DEF，而PEG涂层表现出双重行为，根据光子能量既具有保护作用又具有增强作用。这些见解强调了在未来研究中优化纳米粒子设计和涂层以在基于纳米粒子的放射治疗中最大化治疗效果的重要性。
