Manohar Anagha, M Soundarya, Basavaraj Madivala G, Sudhakar Swathi, Mani Ethayaraja
Department of Applied Mechanics and Biomedical Engineering, Indian Institute of Technology Madras, Chennai 600036, India.
Polymer Engineering and Colloid Science Lab, Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai 600036, India.
Langmuir. 2024 Jul 2;40(26):13613-13621. doi: 10.1021/acs.langmuir.4c01175. Epub 2024 Jun 19.
Flash nanoprecipitation is a simple and scalable method to produce nanoparticles by rapid mixing of a polymer solution with an antisolvent. High-speed mixing devices for the continuous synthesis of polymeric nanoparticles and drug-encapsulated nanoparticles have been designed. In this work, we demonstrate a different approach to induce flash nanoprecipitation using the differential evaporation of solvents in a sessile drop. To show proof of concept, we use polymethyl-methacrylate (PMMA) dissolved in a tetrahydrofuran (THF)-water mixture as a model system. A sessile drop of the polymer solution is allowed to dry under controlled conditions. The sessile drops of the PMMA-THF-water ternary mixture are observed to dry in the constant radius mode. As THF in the drop evaporates faster than water, PMMA supersaturates and precipitates as nanoparticles. Although coffee-ring formation is well-studied in the drying of colloidal suspensions, this work demonstrates the formation of nanoparticles in situ due to a change of solvent quality and subsequent deposition of particles at the pinned contact line. Using the theory of drying of binary solutions, we calculate the temporal variation of composition. The drying paths passing through the low-concentration branch of the binodal give rise to nanoparticles, whereas those passing through the high-concentration branch yield porous films. Spherical polymeric nanoparticles in the size range of 250-700 nm were synthesized using this technique starting from drops with different initial polymer concentration. The method is a cost-effective (no high-speed mixing is required) and scalable alternative to conventional flash nanoprecipitation for synthesizing polymeric nanoparticles for potential applications in drug delivery, diagnostics, and polymer recycling.
快速纳米沉淀法是一种通过将聚合物溶液与反溶剂快速混合来制备纳米颗粒的简单且可扩展的方法。已设计出用于连续合成聚合物纳米颗粒和药物包封纳米颗粒的高速混合装置。在这项工作中，我们展示了一种不同的方法，即利用静滴中溶剂的差异蒸发来诱导快速纳米沉淀。为了证明概念，我们使用溶解在四氢呋喃（THF）-水混合物中的聚甲基丙烯酸甲酯（PMMA）作为模型系统。让聚合物溶液的静滴在受控条件下干燥。观察到PMMA-THF-水三元混合物的静滴以恒定半径模式干燥。由于液滴中的THF比水蒸发得更快，PMMA过饱和并沉淀为纳米颗粒。尽管在胶体悬浮液干燥过程中对咖啡环的形成已有充分研究，但这项工作证明了由于溶剂质量的变化以及随后颗粒在固定接触线处的沉积而原位形成纳米颗粒。利用二元溶液干燥理论，我们计算了组成的时间变化。通过双节线低浓度分支的干燥路径会产生纳米颗粒，而通过高浓度分支的干燥路径会产生多孔膜。使用该技术从具有不同初始聚合物浓度的液滴开始合成了尺寸范围为250 - 700 nm的球形聚合物纳米颗粒。该方法是一种经济高效的（无需高速混合）且可扩展的替代传统快速纳米沉淀的方法，用于合成聚合物纳米颗粒，在药物递送、诊断和聚合物回收等潜在应用中具有重要价值。
