Assembly of Ring‐Shaped Phosphorus within Carbon Nanotube Nanoreactors

A phosphorus allotrope that has not been observed so far, ring‐shaped phosphorus consisting of alternate P₈ and P₂ structural units, has been assembled inside multi‐walled carbon nanotube nanoreactors with inner diameters of 5–8 nm by a chemical vapor transport and reaction of red phosphorus at 500 °C. The ring‐shaped nanostructures with surrounding graphene walls are stable under ambient conditions. The nanostructures were characterized by high‐resolution transmission electron microscopy, scanning transmission electron microscopy, energy‐dispersive X‐ray spectroscopy, Raman scattering, attenuated total reflectance Fourier transform infrared spectroscopy, and X‐ray photoelectron spectroscopy.     

Enzyme Encapsulation by a Ferritin Cage

Ferritins, conserved across all kingdoms of life, are protein nanocages that evolved to mineralize iron. The last several decades have shown that these cages have considerable technological and medical potential owing to their stability and tolerance to modification, as well as their ability to template nanoparticle synthesis and incorporate small molecules. Here we show that it is possible to encapsulate proteins in a ferritin cage by exploiting electrostatic interactions with its negatively charged interior. Positively supercharged green fluorescent protein is efficiently taken up by Archaeoglobus fulgidus ferritin in a tunable fashion. Moreover, several enzymes were readily incorporated when genetically tethered to this fluorescent protein. These fusion proteins retained high catalytic activity and showed increased tolerance to proteolysis and heat. Equipping ferritins with enzymatic activity paves the way for many new nanotechnological and pharmacological applications.