Purpose

Nanoparticle drug delivery systems are typically designed such that the drug is uniformly dispersed in their structure. Considering this point, clearly much amount of drug is inevitably present in outer layers. Hence, any unpredictable degradation leads to premature drug release with subsequent off-target toxicity. To overcome these issues, a new model of nanoparticles with a non-uniform drug concentration pattern is proposed.

Methods

In this new model, much amount of drug is located in the central parts of the sphere and decreases to eventually reach zero at the outermost layer. A numerical simulation is performed to model this system. Four different non-uniform patterns, including linear, 2nd order (type 1 and 2), and cosine, have been examined through this study.

Results

Results reveal that the general behavior of nanoparticles is affected by the way the drug is distributed in its structure. In non-uniform cases, nanoparticle degradation and subsequent drug release rate are significantly slower than the uniform state, for instance, after passing 11 h, about 90% of nanoparticle with uniform pattern has been degraded, while only an average of 18% was lost from non-uniform cases during this period; thus these new nanoparticles offer more stability for long-term circulation. In non-uniform approach, as opposed to uniform, no initial burst release is observed, and drug release profile follows almost a linear pattern. Furthermore, results show an average increase of 45% in final drug concentration after non-uniform nanoparticles’ fully degradation compared to uniform one.

Conclusion

Based on these findings, by the development of such designs, more efficient drug delivery will be somehow guaranteed.

中文翻译：

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药物浓度分布不均匀的纳米粒子的建模和分析：如何实现程序化给药？

目的

纳米颗粒药物递送系统通常被设计成药物均匀分散在它们的结构中。考虑到这一点，外层中不可避免地存在大量药物。因此，任何不可预知的降解都会导致药物过早释放，从而导致脱靶毒性。为了克服这些问题，提出了一种具有非均匀药物浓度模式的纳米颗粒新模型。

方法

在这个新模型中，大量药物位于球体的中心部分，并逐渐减少，最终在最外层达到零。执行数值模拟来模拟该系统。通过本研究检查了四种不同的非均匀模式，包括线性、二阶（类型 1 和 2）和余弦。

结果

结果表明，纳米颗粒的一般行为受到药物在其结构中分布方式的影响。在不均匀的情况下，纳米颗粒的降解和随后的药物释放速度明显慢于均匀状态，例如，经过 11 小时后，约 90% 的均匀图案纳米颗粒被降解，而平均只有 18% 的损失在此期间的非统一案例；因此，这些新的纳米粒子为长期循环提供了更高的稳定性。在非均匀方法中，与均匀相反，没有观察到初始突释，并且药物释放曲线几乎遵循线性模式。此外，结果显示，与均匀纳米粒子相比，非均匀纳米粒子完全降解后最终药物浓度平均增加了 45%。

结论

基于这些发现，通过开发这样的设计，可以以某种方式保证更有效的药物输送。