## 3 Results and Discussion
### Antifungal Activity  
The antifungal activity of **Cu(AZPY)-MOF** was examined on yeast-type (_C. albicans_) and filament-type (_A. niger_) fungi. Cell and spore viability was significantly reduced in both fungi after the 1-day treatment with **Cu(AZPY)-MOF** (Figures 3 and 4). The decrease in CFU number increases with increasing concentrations of **Cu(AZPY)-MOF** in both fungi (Figures 3 and 4). In _C. albicans_, an approximately 75% reduction in CFU number (0.6 log reduction) was observed after treatment with 0.125 mg/mL **Cu(AZPY)-MOF**, and a 98-99.6% reduction (1.8-2.5 log reduction) was observed after treatments with 0.25, 0.35 and 0.5 mg/mL **Cu(AZPY)-MOF** (Figure 3). In _A. niger_, an approximately 60% reduction in CFU number (0.2 log reduction) was observed after the treatment with 0.125 mg/mL **Cu(AZPY)-MOF**, and a 97-99.6% reduction (1.5-2.5 log reduction) was observed after  
Figure 1: SEM image of Cu(AZPY)-MOF.  
Figure 2: PXRD patterns of **Cu(AZPY)-MOF**. The simulated pattern from the X-ray data (**a**), the pattern for the as-prepared sample (**b**), the pattern for the sample after 1 day in H\({}_{2}\)O (**c**) and the pattern for the sample after 1 day in PBS (**d**).  
treatments with 0.25, 0.35, and 0.5 mg/mL **Cu(AZPY)-MOF** (Figure 4). Generally, no dramatic difference in inactivation efficiency was observed between _C. albicans_ and _A. niger_, although the viability of _C. albicans_ cells slightly decreased under treatment with the same concentration of **Cu(AZPY)-MOF** (Figures 3 and 4). Over 99% of cells or spores were inactivated in the treatments with 0.35 and 0.5 mg/mL **Cu(AZPY)-MOF** (Figures 3 and 4), which indicates that these concentrations may be efficient doses to eradicate fungal cells and spores regardless of species.  
Figure 4: Antifungal activities of **Cu(AZPY)-MOF** against _A. niger_. (**a**) Fungal spore viability indicated as the CFU number, Log\({}_{10}\)(CFU number), and relative percentage after 1 day of treatment with **Cu-MOF**. Each germinated spore was considered a CFU. Each value in CFU number was an average of nine replicate measurements. Log10 (CFU number) and relative percentage were calculated using the average value of CFU number. *** \(p<0.01\). (**b**) Pictures of plates showing CFU. The cell suspension was diluted \(10^{5}\) times after the treatment with **Cu(AZPY)-MOF** and 100 \(\mu\)L was spread onto the plates.  
Figure 3: Antifungal activities of **Cu(AZPY)-MOF** against _C. albicans_. (**a**) Yeast cell viability indicated as the CFU number, Log\({}_{10}\)(CFU number), and relative percentage after 1 day of treatment with **Cu-MOF**. Each value in CFU number was an average of nine replicate measurements. Log\({}_{10}\) (CFU number) and relative percentage were calculated using the average value of CFU number. *** \(p<0.001\). (**b**) Pictures of plates showing CFU. The cell suspension was diluted \(10^{4}\) times after treatment with **Cu(AZPY)-MOF** and 100 \(\mu\)L was spread onto the plates.  
Our results demonstrate that **Cu(AZPY)-MOF** has much greater antifungal activity than the constructed Cu-MOFs and Co-CPs in our previous studies [39, 40]. **Cu(AZPY)-MOF** inactivated fungi faster (1-day treatment in this study vs. 4-day treatment in the previous study) with a lower amount than Cu-MOF and Co-CPs. **Cu(AZPY)-MOF** inactivated over 99% of fungal cells or spores at 0.35-0.5 mg/mL after 1 day, while the previously constructed Cu-MOFs and Co-CPs showed 50-80% and 44-99% fungal inactivation, respectively, at 2 mg/mL after 4 days [39, 40].