Light-Addressable Capsules as Caged Compound Matrix for Controlled Triggering of Cytosolic Reactions

摘要

Layer-by-layer assembly was introduced almost two decades ago as a versatile technique for the construction of thin multiple-layer films composed out of polyelectrolytes.2' Shortly after, the concept was extended from planar to spherical geometry, resulting in polyelectrolyte multilayer capsules. The semipermeable wall of the capsules (with a thickness of a few nanometers) and the cavity can be further loaded with inorganic colloidal nanoparticles (NPs) made of different materials and with multiple cargos, respectively (Figure 1). The resulting multifunctional capsules are well-suited for in vitro delivery of cargo inside cells. This concept has been highlighted in several recent reviews. Meanwhile technology has advanced to a point at which these capsules could be a helpful tool for controlled multifunctional in vitro delivery. Nowadays the cavity of capsules can be loaded with a large variety of cargo. While large molecules such as proteins will be readily kept inside the cavity, small molecules need to be either linked to macro-molecules such as dextran, or be embedded inside micelles. The micelle approach even allows for encapsulation of small hydrophobic molecules. The materials forming the polyelectrolyte wall can be chosen such that capsules internalized by cells are not degraded and preserve their cargo over weeks. Leakage of the cargo molecule is reduced and controlled release of cargo upon external stimuli can be performed.