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γ-MnO2 nanomaterials play an essential role in the development of advanced electrochemical energy storage and conversion devices with versatile industrial applications. Herein, novel dandelion-like hollow microspheres of γ-MnO2 mesocrystals have been fabricated for the first time by a one-pot biomineralization route. Recombinant collagen with unique rod-like structure has been demonstrated as a robust template to tune the morphologies of γ-MnO2 mesocrystals, and a very low concentration of collagen can alter the nanostructures of γ-MnO2 from nanorods to microspheres. The as-prepared γ-MnO2 mesocrystals formed well-ordered hollow microspheres composed of delicate nanoneedle-like units. Among all the reported γ-MnO2 with various nanostructures, the γ-MnO2 microspheres showed the most prowess to maintain high discharge capacities after 100+ cycles. The superior electrochemical performance of γ-MnO2 likely results from its unique hierarchical micro-nano structure. Notably, the γ-MnO2 mesocrystals display high biocompatibility and cellular activity. Collagen plays a key dual role in mediating the morphology as well as endowing the biofunction of the γ-MnO2 mesocrystals. This environmentally friendly biomineralization approach using rod-like collagen as the template, provides unprecedented opportunity for the production of novel nanostructured metal oxides with superior biocompatibility and electrochemical performance, which have great potential in advanced implantable and wearable health-care electronic devices.

γ-MnO

Construction of protein–inorganic hybrid materials with hierarchical nanostructures is critical for the creation of advanced multi-functional materials. We herein for the first time report the synthesis of protein–manganese phosphate hybrid nanomaterials by environmentally amiable biomineralization approach. We have demonstrated that collagen provides an excellent biotemplate to modulate the morphology of the hybrid materials, leading to exquisite nanoflowers with branched petals. In this time-dependent biomineralization process, collagen played an essential role in the production of protein–manganese phosphate hybrid materials by inducing the nucleation of manganese phosphates to form a scaffold as well as serving as a glue to hold the petals together. The as-prepared CL–Mn3(PO4)2 nanoflowers exhibited good catalytic activity towards water oxidation. The unique (Gly–X–Y)n amino acid sequences and triple helix structure may provide extraordinary capability for collagen to create hybrid nanomaterials via collagen-templated biomineralization. The single-size and high purity may endow recombinant collagen as a powerful strategy to establish superior biotemplates. This facile and green approach to produce collagen–manganese phosphate hybrid nanoflowers greatly advances our capability to construct manganese phosphates-based functional materials.

The development of novel strategies to construct collagen mimetic peptides capable of self-assembling into higher-order structures plays a critical role in the discovery of functional biomaterials. We herein report the construction of a novel type of amphiphile-like peptide conjugating the repetitive triple helical (GPO)m sequences characteristic of collagen with terminal hydrophilic aspartic acids. The amphiphile-like collagen mimic peptides containing a variable length of (Gly-Pro-Hyp)m sequences consistently generate well-ordered nanospherical supramolecular structures. The C-terminal aspartic acids have been revealed to play a determinant role in the appropriate self-assembly of amphiphile-like collagen mimic peptides. Their presence is a prerequisite for self-assembly, and their lengths could modulate the morphology of final assemblies. We have demonstrated for the first time that amphiphile-like collagen mimic peptides with terminal aspartic acids may provide a general and convenient strategy to create well-defined nanostructures in addition to amphiphile-like peptides utilizing β-sheet or α-helical coiled-coil motifs. The newly developed assembly strategy together with the ubiquitous natural function of collagen may lead to the generation of novel improved biomaterials.