Molecular cages |
1 nm–20 nm |
Release by bond rupture |
Instantaneous chemical gradients, studies with single molecules |
Vesicles and liposomes |
100 nm–100 μm |
High concentration, release by diffusion or rupture |
Chemistry within confined spaces, low numbers of molecules, rapid mixing by diffusion |
Polyelectrolyte capsules and their assemblies |
10 μm–1 mm |
3D spherically symmetric diffusion, 1D ejection, confinement |
Studies of spatially-confined chemical reactions, 1D chemical delivery |
Polymer microspheres |
1 μm–100 μm |
Spherically-symmetric release by diffusion or degradation |
Drug delivery, cell taxis and embryonic studies |
Lithographically-structured containers |
100 nm–1 cm |
Symmetric and asymmetric diffusion and/or degradation |
Drug delivery and cell encapsulation therapy |
Self-assembled polyhedra |
100 nm–1 cm |
Arbitrary space curve by diffusion through precisely positioned pores |
Bacterial chemotaxis, drug delivery, cell encapsulation therapy |
Matrices with immobilized chemicals |
1 μm–10 cm |
3D bound |
Engineering cellular microenvironments for cell and tissue engineering |
Arrays |
100 nm–1 cm |
2D/3D diffusion, 2D/3D bound |
Periodic patterns in reaction-diffusion and biological systems |
Droplet microfluidics |
1 μm–1 mm |
Confinement, 3D diffusion |
Chemistry within confined spaces, control over reaction rates, cell encapsulation |
2D microfluidic networks |
10 μm–10 cm |
2D flow and diffusion |
Cellular chemotaxis, chemistry in laminar flows, substrate patterning |
3D microfluidic networks |
100 μm–10 cm |
3D flow and diffusion |
3D gradients in gels |