Fuyao Liu,Xiuxia He,Junping Zhang,Huimao Zhang,Zhenxin Wang
Hydrophobic ultrasmall nanoparticles synthesized in nonpolar solvents exhibit great potential in biomedical applications. However, a major challenge when applying these nanomaterials in biomedical research is the lack of a versatile strategy to render them water dispersible while preserving the hydrodynamic diameter (HD) to be less than 8 nm for efficient renal clearance. To address this problem, tryptone is employed as the novel ligand to fabricate a simple, versatile, and inexpensive strategy for transferring hydrophobic NaGdF 4 nanodots (3 nm in diameter) from organic phase into aqueous phase without any complicated organic synthesis. The paramagnetic properties of NaGdF 4 nanodots are well retained after the phase transfer process. In particular, the tryptone–NaGdF 4 nanodots have ultrasmall HD (ca., 7.5 nm), which greatly improves their tumor accumulation and facilitates renal clearance within 24 h postinjection. The as-prepared tryptone–NaGdF 4 nanodots can also be further functionalized with other molecules for extensively biomedical and bioanalytical applications. Furthermore, the proposed strategy can easily be extended to transfer other types of inorganic nanoparticles from hydrophobic to hydrophilic for facilitating biomedical applications.
The concentration of intracellular reactive oxygen species directly determines the effect of photodynamic therapy. Reducing intracellular glutathione (GSH) content can increase reactive oxygen species (ROS) level. Therefore, it is extremely important to construct a nanoplatform that can promote photodynamic therapy by consuming GSH. In this study, we synthesized Cu–typtone complex nanoparticles (Cu–Try NPs) by a simple green method and demonstrated their ability to consume GSH to increase intracellular ROS for the first time. Photosensitizer methylene blue was loaded onto Cu–Try NPs (Cu–Try/MB NPs) for enhanced photodynamic therapy. Studies in vitro and in vivo illustrated that enhanced photodynamic therapy based on Cu–Try/MB NPs can kill cancer cells effectively.
In this study, the combined bactericidal effect of nisin and thymoquinone (TQ) on Listeria monocytogenes was investigated in Tryptone Soy Broth (TSB) and sterilized milk. The combined treatment resulted in a greater reduction in bacterial number than either nisin or TQ treatment alone. Nisin and TQ respectively caused depolarization and hyperpolarization of the cell membrane of L. monocytogenes , which indicated early injury to the bacteria. Confocal laser scanning microscopy and N -phenyl-l-naphthylamine uptake assay showed disruption of the cell membrane on treatment. Field emission scanning electron microscopy revealed depression and collapse of the cell surface following treatment with nisin and TQ. Growth curves showed that nisin and TQ acted on the bacteria in different growth phases. Fourier-transform infrared spectroscopy demonstrated a reversible hydrogen-bonding interaction between nisin and TQ. Our results suggest that nisin combined with TQ is a more effective antibacterial effect against L. monocytogenes in both TSB and in sterilized milk than either agent alone. Our study sheds light on the inhibitory mechanisms of nisin, TQ, and their combination, and provides a theoretical basis for the synergistic antibacterial application of nisin and TQ in the food industry.
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