Protein-based smart microtubes and nanotubes as ultrasmall biomaterials

Abstract

This review highlights the latest research on protein-based smart microtubes (MTs) and nanotubes (NTs) as ultrasmall biomaterials that are designed for use in biochemical and biomedical applications. These practical cylinders were prepared using an alternate layer-by-layer assembly of proteins (including enzymes and antibodies) and oppositely charged poly(amino acids) into a track-etched micro/nanoporous polycarbonate (PC) membrane with the subsequent dissolution of the template. The multilayered tube structure resembles a rolled sandwich. Various functionalities can be introduced into the inner surface, cylindrical wall, and outer surface. The inner surface-modified NTs can capture nanoparticles (NPs), viruses, and bacteria in capillaries. The tubules containing enzymes and AuNPs in stratiform walls act as microreactors for hydrolysis and polymerization. Moreover, MTs with PtNPs or catalase as an interior surface are self-propelled in an aqueous H2O2 solution by jetting O2 bubbles from the open-end terminus. These swimming tubes efficiently captured Escherichia coli. like a micromop. Avidin-coated MT motors caught biotinylated particles. Enzyme-coated swimming tubes accelerated catalytic reaction by their stirring motion. Ureaseinterior MTs swim slowly without bubble ejection. A perspective of the practical use of protein-based MTs and NTs with a good biofriendly nature is also described.