To evaluate biomedical potential, the pH stability of [(UiO-66)0.5(agZIF-UC-7)0.5], agZIF-UC-7 and UiO-66 in phosphate-buffered saline (PBS) solution was monitored over time (Fig. ). PBS, with a physiological pH of 7.4, mimics the concentration of ions in the human body and is widely used in biomedical research. The pH increased over time for agZIF-UC-7, likely due to imidazolate linker release, previously shown by ZIF-8, [Zn(mIm)2], where mIm is 2-methylimidazolate. UiO-66 caused pH decline, attributed to phosphate-induced degradation and terephthalate release. In contrast, [(UiO-66)0.5(agZIF-UC-7)0.5] showed minimal pH changes, maintaining a stable environment, which is crucial for biomedical applications because it can protect drugs from environment-induced degradation and allow for slower release of encapsulated drug molecules within the composite. PXRD analysis after PBS immersion over four days confirms UiO-66's degradation, where an amorphous pattern and lack of Bragg peaks are evident (Fig. ). However, in the composite, [(UiO-66)0.5(agZIF-UC-7)0.5], UiO-66 retained its crystallinity, highlighting the agZIF-UC-7 matrix's ability to effectively stabilise the crystal structure of UiO-66 in PBS and prevent its degradation. Methylene blue (MB) dye uptake in PBS was also tested to explore the composite's drug delivery properties, used here as a proxy for drug molecules. MB is efficiently adsorbed by UiO-66 in neutral/basic solutions. All samples were immersed in 5 ppm PBS solutions over time (Fig. ). After 8 hours, adsorption plateaus at 92%, 62%, and 81% were observed for UiO-66, agZIF-UC-7 and the composite respectively. Despite the composite's lower UiO-66 molar ratio, its adsorption activity was comparable to pristine UiO-66, likely because its stable pH environment (the adsorption capacity of UiO-66 increases as pH increases). PXRD analysis on UiO-66 and the composite after 24-hour immersion in MB/PBS solution (Fig. ) shows UiO-66 has degraded as only an amorphous pattern is visible, whereas UiO-66 Bragg peaks are still evident in the composite's PXRD, again showcasing the enhanced stability of UiO-66 in the glass matrix relative to pristine UiO-66.