Nanotubes Resolve Serum Proteins

Polyacrylamide gel electrophoresis is an indispensible tool for separating mixtures of proteins. But applying the technique to a highly complex biological brew such as human serum leads to a smeared mess of unresolved proteins. By introducing functionalized carbon nanotubes to a gel, scientists led by Jin Ouyang of Beijing Normal University have found they can resolve the components of human serum into sharp, clear bands (Nano Lett., DOI: 10.1021/nl802935s). The researchers added two types of nanotubes to different regions of the gels and observed the effects. Introducing carboxylate-coated multiwalled carbon nanotubes to different parts of the resolving portion of the gel, where the sample components are separated, made it easier to isolate specific proteins. Meanwhile, single-walled carbon nanotubes coated with the surfactant Triton X-100 were good at partially absorbing the abundant protein immunoglobulin G when added to the stacking portion of a gel, where the sample is loaded. This approach allowed the researchers to resolve some low-abundance proteins. The researchers also showed that adding single-walled nanotubes in the stacking gel enables them to determine the serum levels of two proteins that could be used to diagnose liver disease.