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Figure 4. 3D architecture-synthesis relationship of MNPs@ZIF-8 samples. 3D volume of reference Au NPs@ZIF-8 (A); Pd NPs@ZIF-8 (B); samples with twice synthesis time (C); samples with 1.15 times, 2-fold MNPs concentration (D and E); samples with 1.25 times Zn²⁺: ligand ratio (F); 1 × 10^-4 wt.% and 5 × 10^-4 wt.% extra PVP addition samples (G and H); respectively; (I) Quantitative comparison of MNPs dispersion and encapsulation. Aggregation ratios of MNPs within blue circles shows approximate equivalence; (J) Radial distribution fitting curves of MNPs for all samples. Curves fit either exponential decay or “plateau + exponential decay” models; (K) Gaussian fitting of nearest-neighbor distances for all samples. Additional PVP specifically induces both peak shift and broadening in Gaussian fitting curves. The orange arrow in (C) points to the shallowly encapsulated MNPs. NP: Nanoparticle; MNP: metal nanoparticle; PVP: polyvinylpyrrolidone; NND: nearest-neighbor distance; MNPs@ZIF-8: metal nanoparticles encapsulated within zeolitic imidazolate framework-8.