High porosities, large surface areas, and tunable functionalities made metal-organic frameworks (MOFs) as effective carriers for drug delivery. One of the most promising MOFs is the zeolitic imidazolate framework (ZIF-8) crystal, an advanced functional material for small-molecule delivery, due to its high loading ability and pH-sensitive degradation. As a novel carrier, ZIF-8 nanoparticles were used in this work to control the release of an autophagy inhibitor, 3-methyladenine (3-MA), and prevent it from dissipating in a large quantity before reaching the target. The cellular uptake in HeLa cells of 3-MA encapsulated in ZIF-8 (3-MA@ZIF-8 NPs) is facilitated through the nanoparticle internalization with reference to TEM observations and the quantitative analyses of zinc by ICP-MS. The autophagy-related proteins and autophagy flux in HeLa cells treated with 3-MA@ZIF-8 NPs show that the autophagosome formation is significantly blocked, which reveals that the pH-sensitive dissociation increases the efficiency of autophagy inhibition at the equivalent concentration of 3-MA. In vivo experiments, when compared to free 3-MA, 3-MA@ZIF-8 NPs show a higher antitumor efficacy and repress the expression of autophagy-related markers, Beclin 1 and LC3. It follows that ZIF-8 is an efficient drug delivery vehicle in antitumor therapy, especially in inhibiting autophagy of cancer cells.

Twelve gemini quaternary ammonium surfactants have been employed to evaluate the antibacterial activity and in vitro cytotoxicity. The antibacterial effects of the gemini surfactants are performed on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) with minimum inhibitory concentrations (MIC) ranging from 2.8 to 167.7 μM. Scanning electron microscopy (SEM) analysis results show that these surfactants interact with the bacterial cell membrane, disrupt the integrity of the membrane, and consequently kill the bacteria. The data recorded on C6 glioma and HEK293 human kidney cell lines using an MTT assay exhibit low half inhibitory concentrations (IC50). The influences of the gemini surfactants on the cell morphology, the cell migration ability, and the cell cycle are observed through hematoxylin-eosin (HE) staining, cell wound healing assay, and flow cytometric analyses, respectively. Both the values of MIC and IC50 decrease against the growth of the alkyl chain length of the gemini surfactants with the same spacer group. In the case of surfactants 12-s-12, the MICs and IC50s are found to decrease slightly with the spacer chain length changing from 2 to 8 and again to increase at higher spacer length (s = 10-12). All of the gemini surfactants show great antibacterial activity and cytotoxicity, and they might exhibit potential applications in medical fields.

A zeolitic imidazolate framework (ZIF-8) with high loading capacity and pH-responsive properties, an important subclass of metal-organic frameworks (MOFs), has become a promising material for drug delivery. A multifunctional drug delivery system (DDS) was designed in this work for effective targeting delivery of chloroquine diphosphate (CQ) as an autophagy inhibitor. The ZIF-8 nanoparticles encapsulating CQ (CQ@ZIF-8 NPs) were fabricated by a simple one-pot method and were then decorated with methoxy poly(ethylene glycol)-folate (FA-PEG), a special identifier of cancer cells, to form FA-PEG/CQ@ZIF-8. The target identification of FA-PEG/CQ@ZIF-8 NPs, compared with CQ@ZIF-8 NPs, leads to an increasing number of NPs being internalized into HeLa cells, which decreases the loss of drugs and results in high cytotoxicity of CQ for cancer cells. The lower viabilities of HeLa cells (cancer cells) and higher viabilities of HEK293 cells (healthy cells) treated with FA-PEG/CQ@ZIF-8 NPs show that the special target for cancer cells results from the combinations of folic acid and folate receptors on the surface of HeLa cells. The quantitative measurements of autophagy-related proteins and the detection of autophagy flux in HeLa cells suggest that the autophagosome formation and autophagy flux are appreciably blocked after the cells are treated with FA-PEG/CQ@ZIF-8 NPs. The ZIF-8 can disintegrate only under low pH conditions, resulting in fast and full release of CQ. The pH-responsive and tumor-targeted properties of the NPs can control the drug release and enhance the efficiency of autophagy inhibition. It indicates that the FA-PEG/CQ@ZIF-8 NPs combining target identification with controlled drug release can be used as a novel model for discussing targeted cancer therapy and inhibiting the autophagy of cancer cells.

A pH- and photothermal-responsive zeolitic imidazolate framework (ZIF-8) compound was designed for loading a dual-drug in the tumor site and improving their curative effects.