Ultrasound-Assisted Processing of Amorphous Hydrated Carbon Oxide from Plant Origin: Properties and Biocompatibility of Conductive Nanocomposites as a Proposal for Food Packaging

The sustainable production of conductive carbon nanomaterials for food-packaging applications remains limited by dispersion instability and safety concerns. Herein, we investigate the ultrasound-assisted processing of plant-derived hydrated amorphous carbon oxide (HACO) to obtain stable, conductive, and biocompatible nanostructured dispersions. Ultrasonic cavitation was applied in a hydroalcoholic medium, and a full 23 factorial design was used to evaluate the effects of sonication amplitude and time on particle size, polydispersity index (PDI), and zeta potential, together with acoustic parameters. Optimized conditions produced dispersions with particle sizes below 150 nm and PDI <0.30 after 24 h, with 1% (v/v) ethanol acting as an effective stabilizer. Raman spectroscopy confirmed an amorphous carbon structure (ID/IG = 0.87), while atomic force microscopy (AFM) and FEG-SEM revealed nanostructured aggregates. Cyclic voltammetry showed peak currents above 30 μA and ΔEp values between 70.8 and 95.2 mV, indicating good electrical conductivity. Although no acute toxicity or mortality was observed in adult zebrafish after 96 h of exposure, the highest concentrations of HSACO (3.0%, v/v) and the pure material induced sublethal behavioral changes. The novelty of this work lies in the combination of renewable, plant-based amorphous carbon oxide and controlled ultrasonic cavitation to produce safe and conductive nanostructures, highlighting HACO as a promising sustainable filler for smart food-packaging nanocomposites.