Analysis of the effects of Cu-MOFs on fungal cell inactivation.

Three dimensional (3D) copper metal organic frameworks (Cu-MOFs) containing glutarates and bipyridyl ligands (bpa = 1,2-bis(4-pyridyl)ethane, bpe = 1,2-bis(4-pyridyl)ethylene, or bpp = 1,3-bis(4-pyridyl)propane) were synthesized by using previously reported hydrothermal reactions or a layering method. All three Cu-MOFs contained well-defined one dimensional (1D) channels with very similar pore shapes and different pore dimensions. The bulk purities of the Cu-MOFs were confirmed using powder X-ray diffraction (PXRD) and infrared spectroscopy (IR) spectra. When the three types of Cu-MOFs were applied to Candida albicans cells and Aspergillus niger spores, an average of about 50-80% inactivation was observed at the highest concentration of Cu-MOFs (2 mg mL -1 ). The efficiency of the fungal inactivation was not significantly different among the three different types (bpa, bpe, bpp). Treatment of the fungi using Cu-MOFs induced an apoptosis-like death and this was more severe in A. niger than C. albicans . This may be due to elevation of the intracellular level of reactive oxygen species (ROS) in A. niger . Generation of the reactive species in solution by Cu-MOFs was observed. However, there was a dramatic variation in the levels observed among the three types. Our results suggest that Cu-MOFs can produce antifungal effects and induce apoptosis-like death of the fungi, which was probably caused by the elevated level of intracellular reactive species.