Figure 3: Characterization of biomimetically mineralized ZIF-8 with biomolecules.

(a) PXRD patterns of the crystals obtained using various biomacromolecules as biomimetic mineralizion agents. Protein encapsulation efficiency: BSA ∼100%, human serum albumin (HSA) ∼100%, OVA ∼100%, lysozyme ∼96%, HRP ∼100%, ribonuclease A ∼86%, haemoglobin ∼90%, trypsin ∼96%, lipase ∼88%, insulin ∼86%, glucose dehydrogenase (PQQ-GDH) ∼82%, urease ∼95%. In each case, the intensity and peak positions of the biocomposites match those of pure ZIF-8. (b–m) Scanning electron microscopy images showing crystals obtained using: (b) OVA, (c) ribonuclease A, (d) HSA, (e) pyroloquinoline quinone-dependent glucose dehydrogenase ((PQQ)GDH), (f) lipase, (g) haemoglobin, (h) lysozyme, (i) insulin, (j) HRP, (k) trypsin, (l) urease and (m) oligonucleotide. Scale bars, 1 μm. While several biomacromolecules induce the standard rhombic dodecahedral morphology for the ZIF-8 biocomposites (c,d,m), other biomacromolecules gave rise to various morphological features such as truncated cubic (e,f,h,i,l), nanoleaf (b), nanoflower (j) and nanostar (k), respectively.