Aloe Vera-conjugated Ag nanoparticles (AgNPs@AV hybrids) are synthesized in large quantities by reducing silver nitrate with Aloe Vera pulp extract at room temperature. TEM image reveals that these NPs are predominantly spherical with an average of 25 nm in diameter. The crystal structure of AgNPs@AV is determined by XRD. The cytotoxicity of AgNPs@AV hybrids is detected by carrying out the cell viability measurement on Human Dermal Fibroblasts (HDF) cells, the results show that no obvious cytotoxicity is observed. Compared with Vera gel and Ag NPs (washed from Vera gel) alone, AgNPs@AV hybrids possess more excellent antibacterial activity on E. coli even at very low concentration.

Mollusk biomineralization is an elaborate process in which cells, organic macromolecules, and calcium carbonate crystals are actively involved. Macromolecules (mainly are proteins and polysaccharide) act as a key role in regulating and limiting the size, orientation, polymorph and texture of inorganic phase. In this work, we focused on the inter-prismatic matrix of mollusk shell combining scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM) analytical techniques with CaCO₃ recrystallization experiment to characterize its structure and effects on crystal formation. Our results show that the inter-prismatic matrix is not a sort of pure polymer, calcite nano-crystals are also located inside the inter-prismatic matrix. Interestingly, it seems that these nanocrystals have a preferred orientation, which means the inter-prismatic matrix do impose effect on the crystal formation. In vitro re-crystallization experiment using partially dissolved prismatic fragment as template indicates that the (104) faces of CaCO₃ micro-crystals are closely associated with the walls of inter-prismatic matrix. Furthermore, a possible growth mechanism of mollusk shell prismatic layer was proposed.