**7. Au-Pt NPs/APTES/FTO**

There have been several studies on the role of Au-Pt nanoparticles (NPs)/APTES/ FTO in vitamin D sensing [24, 100, 101]. In one [102], researchers synthesized Au-Pt NPs with a core-shell structure and functionalized them with aminopropyltriethoxysilane (APTES) to enhance their stability and sensitivity. They then deposited the NPs onto a fluorine-doped tin oxide (FTO) electrode to create a biosensor for the detection of vitamin D. The biosensor exhibited excellent sensitivity and selectivity toward vitamin D, with a linear range of 0.5 to 40 ng/mL and a detection limit of 0.17 ng/mL. The biosensor was also highly stable and reproducible, making it a promising candidate for use in clinical diagnostics.

Another study [103] explored the use of Au-Pt NPs/APTES/FTO for vitamin D sensing. In this study, researchers used a similar approach to functionalize the NPs with APTES and deposit them onto an FTO electrode. They then immobilized vitamin D-binding protein (DBP) onto the surface of the NPs to enhance the specificity of the biosensor toward vitamin D. The biosensor exhibited a linear range of 0.01 to 10 ng/mL and a detection limit of 0.004 ng/mL. The biosensor was also highly selective toward vitamin D, showing minimal cross-reactivity toward other vitamin D metabolites and similar molecules.

Overall, the use of Au-Pt NPs/APTES/FTO biosensors for vitamin D sensing shows great promise due to their high sensitivity, selectivity, stability, and reproducibility. These biosensors have the potential to be developed into simple, cost-effective, and reliable diagnostic tools for monitoring vitamin D levels in clinical settings [24].
