Nanotechnology has experienced significant advancements, attracting considerable attention in various biomedical applications. This innovative study synthesizes and characterizes Ge/PLA/AuNCs (gelatin/PLA/gold nanocomposites) using Syzygium cumini extract to evaluate their various biomedical applications. The UV�Visible spectroscopy results in an absorption peak at 534 nm were primarily confirmed by Ge/PLA/AuNCs synthesis. The FTIR spectrum showed various functional groups and the XRD patterns confirmed the crystalline shape and structure of nanocomposites. The FESEM and HRTEM results showed a oval shape of Ge/PLA/AuNCs with an average particle size of 21 nm. The Ge/PLA/AuNC�s remarkable antioxidant activity, as evidenced by DPPH (70.84 ± 1.64), ABTS activity (86.17 ± 1.96), and reducing power activity (78.42 ± 1.48) at a concentration of 100 μg/mL was observed. The zone of inhibition against Staphylococcus aureus (19.45 ± 0.89 mm) and Echericia coli (20.83 ± 0.97 mm) revealed the excellent antibacterial activity of Ge/PLA/AuNCs. The anti-diabetic activity of Ge/PLA/AuNCs was supported by inhibition of α-amylase (82.56 ± 1.49) and α-glucosidase (80.27 ± 1.57). The anti-Alzheimer activity was confirmed by inhibition of the AChE (76.37 ± 1.18) and BChE (85.94 ± 1.38) enzymes. In vivo studies of zebrafish embryos showed that Ge/PLA/AuNCs have excellent biocompatibility and nontoxicity. The SH-SY5Y cell line study demonstrated improved cell viability (95.27 ± 1.62) and enhanced neuronal cell growth following Ge/PLA/AuNCs treatment. In conclusion, the present study highlights the cost-effective and non-toxic properties of Ge/PLA/AuNCs. Furthermore, it presents an attractive and promising approach for various future biomedical applications. © 2025 Elsevier B.V., All rights reserved.