Working with industry to improve the safety and efficacy of nanomaterial formulations for wood preservation.

Copper (Cu) is the most widely used fungicide for treating wood used in applications where the wood comes into contact with the soil. Currently, there are no satisfactory alternatives to Cu based biocide formulations available that are effective against soft rot and other soil borne fungi. Moreover, Cu is considered a toxicant with relatively low effect on mammals (including humans), although relatively high toxicity is reported for aquatic communities. Nonetheless, not all fungi are sensitive to copper, in fact, several brown rot fungi can grow at ionic concentrations of up to 100 mg/kg. This peculiar category of Fungi produces high economic damage since they are the main cause for the early failure of in-ground timber structures in the US and Europe. The high resistance shown by these Fungi is one of the key factors driving the continuous development of Cu-based formulations and their alternatives.
This study has investigated the antifungal efficacy and mammalian cellular toxicity of different Cu containing formulations including: the standard European benchmark consisting in a molecularly dissolved formulation of copper-amine, a suspension of micronized basic copper carbonate (CuCO3·Cu(OH)2), a dispersion of copper(II)oxide nanoparticles (CuO NPs), a safer by design (SbyD) dispersion of ascorbate coated CuO, and a copper sulphate solution (CuSO4) as an ionic control. The antifungal work includes development of a new protocol for assessing antifungal properties, with significant improvement (reduced uncertainty) over the current standard procedures. The toxic effect against human was assessed using the hepatocarcinoma (C3A) cell line as a liver model as well as via inhalation in a rodent model. The study demonstrates that the ascorbate coating does not increase toxicity, and in some instances decreased toxicity to mammalian cells, but increases efficacy as an antimicrobial agent.