Stress Response of Aspergillus niger Spores to Copper Surfaces and the Implications for Antifungal Surface Functionalization

Abstract

Fungal contaminations pose a persistent challenge in the fields of healthcare, agriculture, and industry, primarily due to their environmental adaptability and increasing resistance to antifungal agents. In this study Aspergillus niger is utilized as model organism. This work evaluates copper, brass, and steel surfaces functionalized with ultrashort pulsed laser-induced periodic surface structures (USP-DLIP) designed as 3 and 9 μm topographies. Fungal spore viability assays show that 9 μm periodicities on copper surfaces achieve a 99% reduction in spore viability, indicating that increased copper ion release is a key factor in enhanced antifungal effectivity. Scanning electron microscopy (SEM) analysis confirm substantial spore damage, linked to the viability testing and the measured copper ion release by inductively coupled plasma triple quadrupole mass spectrometry (ICP-QQQ) spectrometry. Interestingly, 9 μm structured steel surfaces reveal a trend toward antifungal activity despite their inert nature. Whereas structured brass surfaces do not show significant improvement in antifungal activity. These findings suggest USP-DLIP structuring on copper and stainless-steel surfaces have considerable potential for antifungal applications, although interactions between surface structures, released ions, and fungal spores are highly complex. Yet, USP-DLIP offers promising advantages for developing advanced antifungal materials.