Breakthrough Science on Transformation of Fungal Mycelium into Nanostructured Ultrananocrystalline Diamond Material via Microwave Plasma Pyrolysis

Fungal mycelium has been recently promoted as an environmentally sustainable natural material to potentially replace a wide range of materials commonly used today in various technologies, including nano-porous scaffolds for biological cell cultivation, wound dressings, electrical circuit boards, biosensors, substitute leather, building materials and medical bandages. The feasibility of transforming mycelium into carbon-based materials for various nanotechnologies has been previously demonstrated using a Microwave Assisted Pyrolysis (MAP) process, involving microwave (MW) energy to heat polar water molecules contained in biomass, in controlled environments, either directly or via the addition of microwave absorbers such as activated carbon, whereby the natural chitin in the mycelium is carbonized to produce carbon allotropes like biochar or activated carbon in solid or powder form. This abstract describes breakthrough materials science that relates to Nanomaterials, Soft Materials and Biomaterials, and Structural and Functional Materials topics at the MRS Fall meeting 2022. The materials science to be presented relates to research performed by our group developing a transformation of mycelium into a unique nanoscale carbon-based material via a new fast and low-cost pyrolysis process produced in a plasma-reactor integrated into a commonly available kitchen microwave oven. In the novel microwave plasma pyrolysis (MPP) process described in this abstract, the microwave energy is directed to a low pressure (&lt;10 Torr) gaseous environment of Ar gas, flown into a sealed circular quartz tube inside the microwave oven, containing residual atmospheric N₂ and O₂. At the low 10 Torr pressure, the MW power, directed at the flowing gas, induces the formation of a plasma containing Ar⁺, N⁺, O⁺ ions, and Ar⁰, N⁰, O⁰ neutral atoms, and free electrons, all acting on the mycelium biomass, inducing physical / chemical transformations. The data to be presented reveals that the MPP process transform the mycelium into a “myco-diamond” matrix with a unique ultrananocrystalline diamond (UNCD) nanostructure (3-5 nm grains) inserted into macro, micro, and nanoscale structures. The UNCD structure produced by the MPP process is identical to a transformational UNCD coating (3-5 nm grains), previously developed by Auciello’s group using patented MPCVD and HFCVD growth processes. Verification of the MPP-induced transformation of mycelium into UNCD was performed via complementary materials analysis techniques including Raman spectroscopy, for chemical analysis, Scanning Electron Microscopy (SEM), to determine the myco-diamond surface morphology, High Resolution Transmission Electron Microscopy (HRTEM), to confirm UNCD nanostructure, and X-Ray Diffraction (XRD) to confirm diamond structure. All analysis techniques confirmed the formation of UNCD, identical to UNCD coatings previously grown by MPCVD and HFCVD processes¹. The MPP process represents a scalable and low-cost method of producing UNCD nanomaterials derived from renewable biological sources.<br/>O. Auciello, J. J. Alcantar-Peña, E. de Obaldia, Ch. 1-Book,<b> “</b>Ultrananocrystalline Diamond Coatings for New Generation High-Tech and Medical Devices”, O. Auciello (Ed.), Cambridge, July 2022.