Dry Water for Delivery of Biologics to the Airways

泡沫，空气在水中的分散，在日常生活中随处可见：从消防到消费者剃须产品。这种分散体可以通过不可逆地与空气-水界面结合的胶体颗粒来稳定。近年来，人们对通过改变胶体稳定剂的化学性质来改变这些材料的过渡相产生了兴趣。这就导致了一种极不寻常的现象——水在空气中的稳定分散，被称为“干水”。这些材料表现为自由流动的干粉，但其中可能含有98%的水，密度约为1g/cm3。这是气溶胶科学的一大机遇：将稳定、干燥、单分散的粉末输送到气道，这些粉末在其天然溶液结构中含有敏感的治疗性蛋白质。粉末的输送具有很大的优点，包括简单的“绿色”驱动，无需推进剂和一致的粒度，以精确瞄准目标部位。此外，“干水”在输送蛋白质、全细胞和RNA等生物制剂方面具有显著优势，这些生物制剂在没有水的情况下无法稳定。然而，仍然存在几个问题：我们如何为这种应用准备合适粒径的干水？什么是实现有效管理的最佳手段？给药后如何将生物制剂从干燥的水中解放出来？

Foams, dispersions of air in water, are seen in everyday life: from fire-fighting to consumer shaving products. Such dispersions may be stabilised by colloidal particles which are irreversibly bound to the air-water interface. There has been recent interest in the transitional phase inversion of these materials by alteration of colloidal stabiliser chemistry. This leads to an exceedingly uncommon phenomenon - stable dispersions of water in air, known as "dry water". These materials appear as a free-flowing dry powder but which may >98% water, giving a density of ~1g/cm3. Therein lies a big opportunity in aerosol science: the delivery of stable, dry, monodisperse powders to the airways which contain sensitive therapeutic proteins in their native solution structure. Delivery of powders has great advantages including simple "green" actuation without propellant and consistent particle size for precision targeting of the target site. Furthermore, "dry water" has significant advantages in delivering biologics such as proteins, whole cells, and RNA, which cannot be stabilised without water present. However, several questions remain: How can we prepare dry water of the right particle size for this application? What are the best devices to allow effective administration? How can the biologic be liberated from the dry water after administration?