In an effort to improve both the stability of virus-like particles (VLPs) and the medical activity of polyoxometalates (POMs), a new hybrid assembly system between human papillomavirus (HPV) capsid protein L1 and a europium-containing POM (EuW) has been constructed, for the first time, via the electrostatic interactions between them. The co-assembly of EuW and HPV 16 L1-pentamer (L1-p) in buffer solution resulted in the encapsulation of POMs in the cavity of VLPs, which was further confirmed by cesium chloride (CsCl) gradient ultracentrifugation, SDS-PAGE, dynamic light scattering, and transmission electron microscopy, whereas the post-assembly of EuW with the as-prepared VLPs leads to the adsorption of POMs only on the external surface of particles, and both cases improved the thermal and storage stabilities of VLPs obviously. Particularly, the encapsulation of POMs in VLPs largely improved the antibacterial activity of EuW, and thereby, the present study will be significant for both the stability improvement of protein vaccines and the development of POM medicine.

A novel photothermal material based on a polyoxometalate-antioxidant peptide assembly with enhanced photothermal stability and enhanced antibacterial activity was exploited.

In this study, a uniform complex dual micelle bearing a gadolinium-substituted polyoxometalate core, a hydrophobic middle, and a biocompatible organic shell, which exhibits a uniform size and definite molecular weight and chemical composition, is constructed through a simple two-step process for use as a fluorescence and magnetic resonance imaging (MRI) contrast agent. A paramagnetic polyoxometalate cluster, K [Gd(β -SiW O ) ], is first encapsulated with a cationic 3-generation dendron (D-3) bearing triethylene glycol monomethyl ether terminal groups through ionic substitution. The formed electrostatic complex, (D-3) [Gd(β -SiW O ) ] (D-GdSiW), which displays an ambivalent micellar structure, is then demonstrated to act as a suitable carrier for the uptake of cationic fluorescent dyes, forming a loaded complex. The dye-loaded complex D-GdSiW-D is thus proven to display high relaxivity as a contrast agent, maintaining its structural stability under physiological conditions with low cell cytotoxicity. Confocal laser scanning microscopic observation also demonstrates the fluorescence imaging property of the prepared complex upon consumption by MCF-7 cells. Both in vivo fluorescence imaging and MRI further confirm that the complex micelle with dual micellar structure may be a suitable liver-specific contrast agent for clinical diagnosis.

Two hybrid supramolecular complexes comprising magnetic core and dendritic periphery were prepared, which exhibited uniform size, definite molecular weight and chemical composition, and were applicable as enhanced contrast agents.

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