Unveiling the Surface and the Ultrastructure of Palladized Fungal Biotemplates

Abstract

In this paper, two biosystems based on filamentous fungi and Pd nanoparticles (NPs) were synthesized and structurally characterized. In the first case, results concerning the integration and distribution of Pd-NPs on Phialomyces macrosporus revealed that nanoparticles are accumulated on the cell wall, keeping the cytoplasm isolated from abiotic particles. However, the Penicillium sp. species showed an unexpected internalization of Pd-NPs in the fungal cytosol, becoming a promising biosystem to further studies of in vivo catalytic reactions. Next, we report a new solution-based strategy to prepare palladized biohybrids through sequential reduction of Pd2+ ions over previously harvested fungus/Au-NP composites. The chemical composition and the morphology of the biohybrid surface were characterized using a combination of scanning electron microscopy, transmission electron microscopy, and photoelectron spectroscopy. The deposition of Pd0 over the fungal surface produced biohybrids with a combination of Au and Pd in the NPs. Interestingly, other chemical species such as Au+ and Pd2+ are also observed on the outermost wall of microorganisms. Finally, the application of A. niger/AuPd-NP biohybrids in the 3-methyl-2-buten-1-ol hydrogenation reaction is presented for the first time. Biohybrids with a high fraction of Pd0 are active for this catalytic reaction.

Exploring Culture Media Diversity to Produce Fungal Secondary Metabolites and Cyborg Cells

“…[20,59] Filamentous fungi offer a large interaction surface through their mycelial structure, contributing to efficient processes in manipulating structures within the nanoscale range. [60,61] Therefore, selecting a culture medium significantly influences the efficacy of fungi in nanobiotechnology studies.…”

“…[30,33] During the growth of microorganisms through carbon metabolism, abiotic nanomaterials are incorporated, such as metal nanoparticles, transition metal oxides, quantum dots, carbon nanotubes, graphene oxide, and others, onto the fungal wall. [21,34,60,61] From a chemical perspective, the cell wall of filamentous fungi is the essential structure for the formation of biohybrids. The ability of microorganisms to [33] b) Obtaining fungal biohybrids.…”

“…due to their enhanced capability to assimilate particulate materials. [21,60,61,70] Tables 1 and 2 detail preparing the culture media.…”

“…Nowadays, the utilization of filamentous fungi in nanotechnology has become a topic of increasing significance because of their rapid growth, ease of cultivation, and unique enzymatic capabilities, making them well‐suited for nanoparticle synthesis and the development of bio‐hybrid entities called cyborg cells [20,59] . Filamentous fungi offer a large interaction surface through their mycelial structure, contributing to efficient processes in manipulating structures within the nanoscale range [60,61] . Therefore, selecting a culture medium significantly influences the efficacy of fungi in nanobiotechnology studies.…”

“…Specifically for filamentous fungi, in this approach, the cultivation of microorganisms in a medium containing discrete nanometric particles results in the assimilation of these non‐biological objects into the fungal ultrastructure [30,33] . During the growth of microorganisms through carbon metabolism, abiotic nanomaterials are incorporated, such as metal nanoparticles, transition metal oxides, quantum dots, carbon nanotubes, graphene oxide, and others, onto the fungal wall [21,34,60,61] . From a chemical perspective, the cell wall of filamentous fungi is the essential structure for the formation of biohybrids.…”