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首页> 外文期刊>Crystal growth & design >Control of Heterogeneous Nucleation via Rationally Designed Biocompatible Polymer Surfaces with Nanoscale Features
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Control of Heterogeneous Nucleation via Rationally Designed Biocompatible Polymer Surfaces with Nanoscale Features

机译：通过合理设计的具有纳米级特征的生物相容性聚合物表面控制非均相成核

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Direct control of nucleation in a crystallization process is difficult to achieve but offers many potential benefits to the food, chemicals, and pharmaceutical industries. We demonstrate a rational approach for designing and fabricating biocompatible polymer films that can drastically enhance nucleation rates and enable polymorph selection of small-molecule compounds. The core design philosophy was to calculate angles between major crystal faces and determine suitable substrate geometry to use for enhancing heterogeneous nucleation. Aspirin and indomethacin were used as model compounds; poly(vinyl alcohol) (PVA) with no additional chemical modification was made into films and imprinted with nanoscale features. Nucleation induction time experiments showed that using PVA films significantly reduced the nucleation induction time at a fixed supersaturation due to favorable chemical interactions and could be further reduced when the angles of the nano-indentations on the substrate matched the angles between different crystalline faces. X-ray diffraction (XRD) was used to reveal the interactions between the model compounds and PVA to suggest possible molecular packing in the indentations. Induction time and XRD results demonstrated validity of the rational design approach based on angle-directed nucleation. Finally, polymorph selection toward gamma-indomethacin with PVA substrates showed that it is possible to control polymorph composition of the final crystalline product by kinetically controlling the nucleation process. For the aspirin system, the 85 degrees angle led to the highest rate of nucleation; for the polymorphic indomethacin system, XRPD results showed that the gamma form preferentially formed on the PVA films with 65 degrees and 80 degrees angles leading to the largest reduction in nucleation induction time.
机译：难以实现结晶过程中成核的直接控制，但可为食品，化学和制药行业提供许多潜在的好处。我们展示了一种设计和制造生物相容性聚合物膜的合理方法，该膜可以极大地提高成核速率，并能够选择小分子化合物的多晶型物。核心设计理念是计算主晶面之间的角度并确定合适的衬底几何形状，以用于增强异质形核。阿司匹林和消炎痛被用作模型化合物。将没有其他化学修饰的聚乙烯醇（PVA）制成薄膜，并印有纳米级特征。成核诱导时间实验表明，由于有利的化学相互作用，使用PVA膜可显着减少固定过饱和度下的成核诱导时间，并且当基底上的纳米压痕角度与不同晶面之间的角度匹配时，可进一步减少成核诱导时间。 X射线衍射（XRD）用于揭示模型化合物与PVA之间的相互作用，以表明可能存在凹痕中的分子堆积。归纳时间和XRD结果证明了基于角定向成核的合理设计方法的有效性。最后，对具有PVA底物的γ-吲哚美辛的多晶型物选择表明，可以通过动力学控制成核过程来控制最终结晶产物的多晶型物组成。对于阿司匹林系统，85度角导致最高的成核率;对于多形吲哚美辛体系，XRPD结果显示，γ晶型优先在65度和80度角的PVA膜上形成，从而最大程度地减少了成核诱导时间。

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