Moakes Richard J A, Grover Liam M, Robinson Thomas E
Healthcare Technologies Institute, University of Birmingham, Birmingham B15 2TT, UK.
Bioengineering (Basel). 2022 Dec 20;10(1):3. doi: 10.3390/bioengineering10010003.
Structured fluid biomaterials, including gels, creams, emulsions and particle suspensions, are used extensively across many industries, including great interest within the medical field as controlled release vehicles to improve the therapeutic benefit of delivered drugs and cells. Colloidal forces within these materials create multiscale cohesive interactions, giving rise to intricate microstructures and physical properties, exemplified by increasingly complex mathematical descriptions. Yield stresses and viscoelasticity, typically arising through the material microstructure, vastly improve site-specific retention, and protect valuable therapeutics during application. One powerful application route is spraying, a convenient delivery method capable of applying a thin layer of material over geometrically uneven surfaces and hard-to-reach anatomical locations. The process of spraying is inherently disruptive, breaking a bulk fluid in successive steps into smaller elements, applying multiple forces over several length scales. Historically, spray research has focused on simple, inviscid solutions and dispersions, far from the complex microstructures and highly viscoelastic properties of concentrated colloidal biomaterials. The cohesive forces in colloidal biomaterials appear to conflict with the disruptive forces that occur during spraying. This review explores the physical bass and mathematical models of both the multifarious material properties engineered into structured fluid biomaterials and the disruptive forces imparted during the spray process, in order to elucidate the challenges and identify opportunities for rational design of sprayable, structured fluid biomaterials.
结构化流体生物材料，包括凝胶、乳膏、乳液和颗粒悬浮液，在许多行业中广泛应用，在医学领域尤其受关注，作为控释载体以提高所递送药物和细胞的治疗效果。这些材料中的胶体作用力产生多尺度内聚相互作用，导致复杂的微观结构和物理性质，越来越复杂的数学描述便是例证。屈服应力和粘弹性通常由材料微观结构产生，极大地改善了特定部位的滞留，并在应用过程中保护有价值的治疗剂。一种强大的应用途径是喷雾，这是一种方便的递送方法，能够在几何形状不均匀的表面和难以触及的解剖位置上施加一层薄薄的材料。喷雾过程本质上具有破坏性，将大量流体在连续步骤中分解成更小的单元，在多个长度尺度上施加多种力。从历史上看，喷雾研究主要集中在简单的、无粘性的溶液和分散体上，与浓缩胶体生物材料的复杂微观结构和高粘弹性性质相差甚远。胶体生物材料中的内聚作用力似乎与喷雾过程中产生的破坏作用力相冲突。本综述探讨了设计到结构化流体生物材料中的多种材料特性以及喷雾过程中施加的破坏作用力的物理基础和数学模型，以阐明挑战并确定合理设计可喷雾结构化流体生物材料的机会。
