A PVP-assisted pyrolysis strategy that can simply but efficiently transform zeolitic imidazolate framework-67 (ZIF-67) into a Co-embedded N-enriched meso/microporous carbon material (Co-NC) is reported for the first time. Without further acid treatment, Co-NC can reach an excellent electroactivity and long-term durability toward the oxygen-reduction reaction (ORR) and the oxygen-evolution reaction (OER).

We have synthesized a core@shell nanocomposite using biocompatible bovine serum albumin (BSA) as the core and a pH-sensitive metal-organic framework (MOF) as the shell. Doxorubicin (DOX)/BSA nanoparticles as cores have been prepared. A zeolitic imidazolate framework-8 (ZIF-8) layer has been coated on the outer surface of the DOX/BSA core. The ZIF layer acts as a capsule for the safe storage of DOX under physiological conditions. An efficient pH-responsive drug delivery system using a BSA/DOX@ZIF, in which the drug is not released in PBS at pH 7.4 but is released at low pH (5.0-6.0), has been constructed. Compared to the pure ZIF, a better biocompatibility has been obtained using the BSA/DOX@ZIF. The BSA/DOX@ZIF shows a much higher efficacy than free DOX against the breast cancer cell line MCF-7. The positive charges on the outer surface of the BSA/DOX@ZIF also improve its cellular uptake.

The oxygen reduction reaction (ORR) is of significant importance in the development of fuel cells. Now, cobalt-nitrogen-doped chiral carbonaceous nanotubes (l/d-CCNTs-Co) are presented as efficient electrocatalysts for ORR. The chiral template, N-stearyl-l/d-glutamic acid, induces the self-assembly of well-arranged polypyrrole and the formation of ordered graphene carbon with helical structures at the molecular level after the pyrolysis process. Co was subsequently introduced through the post-synthesis method. The obtained l/d-CCNTs-Co exhibits superior ORR performance, including long-term stability and better methanol tolerance compared to achiral Co-doped carbon materials and commercial Pt/C. DFT calculations demonstrate that the charges on the twisted surface of l/d-CCNTs are widely separated; as a result the Co atoms are more exposed on the chiral CCNTs. This work gives us a new understanding of the effects of helical structures in electrocatalysis.