Owing to their unique optical properties （e.g., bright fluorescence coupled with strong photostability） and negligible toxicity, fluorescent silicon nanoparticles （SiNPs） have been demonstrated to be promising probes for bioimaging analysis. Herein, we describe the use of Caenorhabditis elegans （C. elegans） as an animal model to investigate the in vivo behavior and molecular imaging capacity of ultrasmall fluorescent SiNPs （e.g., - 3.9 ± 0.4 nm）. Our studies show that （1） the internalized SiNPs do not affect the morphology and physiology of the worms, suggesting the superior biocompatibility of SiNPs in live organisms; （2） the internalized SiNPs cannot cross the basement membrane of C. elegans tissues and they display limited diffusion ability in vivo, providing the possibility of their use as nanoprobes for specific tissue imaging studies in intact animals; （3） more than 80% of the fluorescence signal of internalized SiNPs remains even after 120 min of continuous laser bleaching, whereas only - 20% of the signal intensity of mCherry or cadmium telluride quantum dots remains under the same condition, indicating the robust photostability of SiNPs in live organisms; and （4） cydic RGD-peptide-conjugated SiNPs can specifically label muscle attachment structures in live C. elegans, which is the first proof-of-concept example of SiNPs for targeted molecular imaging in these live worms. These finding raise exciting opportunities for the design of high-quality SiNP-based fluorescent probes for long-term and real-time tracking of biological events in vivo.
Safe fluorescent gene-transfection vectors are in great demand for basic biological applications and for gene-therapy research. Here, we introduce a new type of luminescent silicon nanoparticle （SiNP）-based gene carrier suitable for determining the intracellular fate of the gene vehicle in a long-term and real-time manner. The presented SiNP-based nanocarriers simultaneously feature strong and stable fluorescence, high DNA-loading capacity and gene-transfection efficienc35 as well as favorable biocompafibility. Taking advantage of these unique benefits, we were able to readily observe the behavior of the gene carriers in live cells （e.g. cellular uptake, intracellular trafficking, and endosomal escape） in a long-term and real- time manner. The results demonstrate the potential usability of these fluorescent SiNP-based gene vectors as powerful tools in the field of gene therapy, and provide invaluable information for understanding the intracellular behavior of gene carriers.
Jingyang Pang Yuanyuan Su Yiling Zhong Fei Peng Bin Song Yao He
CuS microcrystals were successfully prepared through a mild solvothermal reaction in ethylene glycol （EG） with the assistance of cationic surfactant cetyltrimethylammonium bromide （CTAB）. An interesting morphology evolution from flower-like microspheres to hollow microspheres, and finally to smooth nanoflakes was observed when increasing the amount of CTAB. The products were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, and UV-vis spectroscopy. It was found that the amount of CTAB played an important role in determining the morphology of the CuS microcrystals. Electrical measurement reveals that the as-prepared CuS microspheres were of high conductivity, which might favor their device applications. It is expected that CuS microcrystals with controlled morphologies and structures will have important applications in solar cells. This simple but effective method could also be extended to the controlled growth of other inorganic microcrystals.
