## 6 Conclusions  
In summary, the main objective of our study was to understand a novel approach to synthesize vancomycin-functionalized and PEI-stabilized AuNPs for antifungal activity against two filamentous fungi, _A. fumigatus_ and _A. flavus_. Our results showed that the synthesized PEI-AuNP@Van exhibited potent antifungal activity against _A. fumigatus_, with a lower MIC value than PEI-AuNPs. However, it demonstrated a high MIC against _A. flavus_. Our findings also indicated that PEI-AuNP@Van attenuated conidial germination by up to 93% and killed up to 38.4% of _A. fumigatus_ within 8 h of exposure. In contrast, it only caused a 28% killing of _A. flavus_ conidia. The potential mechanism for the differential action of PEI-AuNP@Van against the conidia of _A. fumigatus_ and _A. flavus_ could be related to the higher amount of fibrillary polysaccharides in _A. flavus_, which may limit the binding of PEI-AuNP@Van. Notably, the molecular differences associated with the cell walls of _A. fumigatus_ and _A. flavus_ may also play a role in their differential susceptibility. Our study suggests that designing and exploring antifungal drugs against filamentous fungi using efficient delivery systems, such as AuNPs, could be a promising strategy to address emerging antifungal drug resistance. **Supplementary Materials:** The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app1466926/s1](https://www.mdpi.com/article/10.3390/app1466926/s1)]([https://www.mdpi.com/article/10.3390/app1466926/s1](https://www.mdpi.com/article/10.3390/app1466926/s1)), Figure S1, Optical micrograph of conidial germination inhibition activity of PEI-AuNP@Van and voriconazole along with untreated control against _A. fumigatus_; the data was obtained at several time intervals (i.e., 0, 4, 8, 12, 24, and 48 h); Figure S2, Optical micrograph of conidial germination inhibition activity of PEI-AuNP@Van and voriconazole along with an untreated control against _A. flavus_; the data was captured at several time intervals (i.e., 0, 4, 8, 12, 24, and 48 h); Figure S3, Micrographs of live/dead cells. a and b representing the untreated conidia of _A. fumigatus_, (c and d) representing voriconazole-treated conidia, and (e and f) representing PEI-AuNP@Van treated conidia; Figure S4, Live/dead assay by super-resolution confocal microscopy with respective DIC images. a and b representing the untreated control _A. flavus_ conidia, (c and d) representing voriconazole-treated conidia, and (e and f) representing PEI-AuNP@Van-treated conidia; Figure S5, TEM micrograph of untreated and PEI-AuNP@Van treated conidia of _A. flavus_, showing an electron-dense outer layer: (a) untreated conidia, and (b) treated with PEI-AuNP@Van; Table S1, Raman spectra of voriconazole and PEI-AuNP@Van treated conidia of _A. flavus_ and _A. fumigatus_ along with an untreated control and their spectral assignments (+) = Peak Present; (-) = Peak absent. **Author Contributions:** A.N. and A.K.T. contributed equally to this work. Conceptualization: A.K.T. and M.K.G. ; Data curation: A.K.T. and M.K.G. ; Formal analysis: A.K.T. ; Funding acquisition: M.K.G. ; Investigation: A.N. and A.K.T. ; Methodology: A.N., A.K.T., R.T. and M.K.G. ; Project administration: M.K.G. and P.C.P. ; Resources: M.K.G., P.C.P., S.K. and P.S.B. ; Software: A.K.T. ; Supervision: [PERSON], P.C.P. and [PERSON]; Validation: A.K.T. and M.K.G. ; Visualization: A.N., M.K.G. and P.S.B. ; Roles/Writing--original draft: [PERSON]; Writing--review and editing: [PERSON], [PERSON] and [PERSON]. All authors have read and agreed to the published version of the manuscript. **Funding:** No external funding was received for this work. **Institutional Review Board Statement:** Not applicable. **Informed Consent Statement:** Not applicable. **Data Availability Statement:** The datasets used and/or analyzed in the current study are available in the manuscript and Supplementary Files.