What is it about?
We present experimental imaging/analytical evidences that challenges traditional understandings of self-assembling behaviour of eumelanin superstructures, depending not only on the contact area but also on the shape of domain engagements. The experimental approach demonstrates the efficacy of using conventional vibrational resonance micro-Raman and high-resolution electron microscopies for addressing supramolecular aggregation over functionalized 2D nanosheets.
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Why is it important?
We demonstrate that interfacial contacts over micronized graphene oxide sheets cause effective morpho-structural changes in eumelanin molecules, from their naturally occurring irregular short-range order domains to form diverse superstructures with the biocompatible carbon oxide substrate. In particular, resolution nanodiffraction/imaging analysis evidence new nanocrystalline domains of pure natural eumelanin with different and irregular orientations forming irregular nanosheets. Interestingly, a disassembly and reassembly route of eumelanin units are actually evident not only on the oxide graphene surface but also located in high amounts on the edge of vertical graphene oxide, concretely supported by the analytical changes of the predominant resonance bands (D, D**, and G). This confirms the ability of eumelanin to reassemble in spherical and elongated nanostructures induced by the external stimuli of the graphene oxide in aqueous solution at room temperature. This work thus highlights the assembling mechanisms for designing strategies to control bioactive molecules through environment modification.
Perspectives
This work aims at integrating morphostructural-vibrational informations through a methodology designed to assemble small eumelanin units into superaggregates, an effect driven by the defects present in the graphene oxide layers, which can be used to tailor the optoelectronic properties of complex hybrid materials. To obtain insight into these intriguing and complex hybrid biomaterials, a combination of Raman spectroscopy and electron microscopy imaging, supported by quantitative data/imaging analyses, has been implemented. This research demonstrates once again that nanoscale surfaces can pave the way for the production of a wide range of functional and unconventional nanostructures that could have a significant impact on the nanotechnologies of the future.
Dr Costantino Zazza
Universita degli Studi della Tuscia
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This page is a summary of: Vibrational and Nanoimaging of Eumelanin Superstructures modulated by Functionalized Micronized Graphene Oxide, Nanoscale, January 2025, Royal Society of Chemistry,
DOI: 10.1039/d5nr02546j.
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