Xiaoyue Zhu

Green Synthesis of Bifunctional Fluorescent Carbon Dots from Garlic for Cellular Imaging and Free Radical Scavenging

Nitrogen and sulfur codoped carbon dots (CDs) were prepared from garlic by a hydrothermal method. The as-prepared CDs possess good water dispersibility, strong blue fluorescence emission with a fluorescent quantum yield of 17.5%, and excellent photo and pH stabilities. It is also demonstrated that the fluorescence of CDs are resistant to the interference of metal ions, biomolecules, and high ionic strength environments. Combining with low cytotoxicity properties, CDs could be used as an excellent fluorescent probe for cellular multicolor imaging. Moreover, the CDs were also demonstrated to exhibit favorable radical scavenging activity.

Self-Monitoring and Self-Delivery of Photosensitizer-Doped Nanoparticles for Highly Effective Combination Cancer Therapy in Vitro and in Vivo

Theranostic nanomedicine is capable of diagnosis, therapy, and monitoring the delivery and distribution of drug molecules and has received growing interest. Herein, a self-monitored and self-delivered photosensitizer-doped FRET nanoparticle (NP) drug delivery system (DDS) is designed for this purpose. During preparation, a donor/acceptor pair of perylene and 5,10,15,20-tetro (4-pyridyl) porphyrin (H2TPyP) is co-doped into a chemotherapeutic anticancer drug curcumin (Cur) matrix. In the system, Cur works as a chemotherapeutic agent. In the meantime, the green fluorescence of Cur molecules is quenched (OFF) in the form of NPs and can be subsequently recovered (ON) upon release in tumor cells, which enables additional imaging and real-time self-monitoring capabilities. H2TPyP is employed as a photodynamic therapeutic drug, but it also emits efficient NIR fluorescence for diagnosis via FRET from perylene. By exploiting the emission characteristics of these two emitters, the combinatorial drugs provide a real-time dual-fluorescent imaging/tracking system in vitro and in vivo, and this has not been reported before in self-delivered DDS which simultaneously shows a high drug loading capacity (77.6%Cur). Overall, our carrier-free DDS is able to achieve chemotherapy (Cur), photodynamic therapy (H2TPyP), and real-time self-monitoring of the release and distribution of the nanomedicine (Cur and H2TPyP). More importantly, the as-prepared NPs show high cancer therapeutic efficiency both in vitro and in vivo. We expect that the present real-time self-monitored and self-delivered DDS with multiple-therapeutic and multiple-fluorescent ability will have broad applications in future cancer therapy.

A recyclable carbon nanoparticle-based fluorescent probe for highly selective and sensitive detection of mercapto biomolecules

Carbon nanoparticles (CNPs) with strong blue emission are synthesized using a microwave-assisted hydrothermal method. The fluorescence of the CNPs can be completely quenched by Hg2+ through an effective electron or energy transfer process due to the synergetic strong electrostatic interaction and metal-ligand coordination. Based on this, a system containing Hg2+-quenched CNPs (CNP-Hg2+) is designed to be a sensitive and selective turn-on fluorescent probe towards cysteine (a type of mercapto biomolecule) with a detection limit of 15 nM. The fluorescence of CNP-Hg2+ aqueous solution can be repeatedly turned on and off for over 10 times by alternative addition of cysteine and Hg2+, respectively. After 10 cycles, the fluorescence intensity could be recovered to as high as 85% of the original value of CNPs. Remarkably, the sensing process is able to be observed by the naked eye under UV irradiation. Furthermore, the sensing is specific to biothiols and the sensor is able to work in living cells.

Poking cells for efficient vector-free intracellular delivery

Techniques for introducing foreign molecules and materials into living cells are of great value in cell biology research. A major barrier for intracellular delivery is to cross the cell membrane. Here we demonstrate a novel platform utilizing diamond nanoneedle arrays to facilitate efficient vector-free cytosolic delivery. Using our technique, cellular membrane is deformed by an array of nanoneedles with a force on the order of a few nanonewtons. We show that this technique is applicable to deliver a broad range of molecules and materials into different types of cells, including primary neurons in adherent culture. Especially, for delivering plasmid DNAs into neurons, our technique produces at least eightfold improvement (~45% versus ~1-5%) in transfection efficiency with a dramatically shorter experimental protocol, when compared with the commonly used lipofection approach. It is anticipated that our technique will greatly benefit basic research in cell biology and also a wide variety of clinical applications.

Nanocomposite-strengthened dissolving microneedles for improved transdermal delivery to human skin

Delivery of drugs and biomolecules into skin has significant advantages. To achieve this, herein, a nanomaterial-strengthened dissolving microneedle patch for transdermal delivery is reported. The patch comprises thousands of microneedles, which are composed of dissolving polymers, nanomaterials, and drug/biomolecules in their interior. With the addition of nanomaterials, the mechanical property of generally weak dissolving polymers can be dramatically improved without sacrificing dissolution rate within skin. In this experiments, layered double hydroxides (LDH) nanoparticles are incorporated into sodium carboxymethylcellulose (CMC) to form a nanocomposite. The results show that, by adding 5 wt% of LDH nanoparticles into CMC, the mechanical strength significantly increased. Small and densely packed CMC-LDH microneedles penetrate human and pig skin more reliably than pure CMC ones and attractively the nanocomposite-strengthened microneedles dissolve in skin and release payload within only 1 min. Finally, the application of using the nanocomposite-strengthened microneedle arrays is tested for in vivo vaccine delivery and the results show that significantly stronger antibody response could be induced when compared with subcutaneous injection. These data suggest that nanomaterials could be useful for fabricating densely packed and small polymer microneedles that have robust mechanical properties and rapid dissolution rates and therefore potential use in clinical applications.

Highly stable organic fluorescent nanorods for living cell imaging

Metal-free, organic-dye-based fluorescent nanorods were fabricated through a simple solvent-exchange procedure. The as-prepared nanorods exhibit low toxicity to living cells and excellent photostability. Furthermore, they are stable in solutions of various pHs and high ionic strength and in solutions with interfering metal ions. Compared with the free DPP-Br molecules in THF, these nanorods exhibit larger Stokes shift, broader absorption spectra, and greatly improved photostability. We successfully demonstrated the application of the nanorods, including their aforementioned beneficial characteristics, as a good fluorescence probe for bio-imaging.

Improved polyvinylpyrrolidone microneedle arrays with non-stoichiometric cyclodextrin

Dissolving polymer microneedles have attracted much attention for their biocompatibility, fast dissolution, and high drug loading. Among them, polyvinylpyrrolidone (PVP) is widely used, but its high water absorption and poor mechanical properties constrain its broad applications. Herein we show that adding cyclodextrin (CD) to form PVP-CD inclusion complexes can alleviate these problems. The water absorption of PVP was reduced by 36-40% at different RHs as the PVP-CD inclusion complexes formed. Attractively, the water absorption at 10 and 20 days remained almost the same for the complexes while it could dramatically increase for the pure PVP samples, particularly in high humidity environments, indicating a possibly longer storage time for the complexes. It was also found that the Youngs modulus and hardness of the PVP-CD could be greatly improved, especially for low molecular weight PVP. Furthermore, the glass transition temperature (Tg) of the PVP-CD increased by up to 39 °C. With the improved properties, the fabricated PVP-CD microneedles possessed much sharper needle tips and the patch had less cracks than those made from pure PVP. Pig skin application results suggested that the PVP-CD microneedle arrays were able to reliably pierce the stratum corneum of the skin while it was not achievable for the PVP microneedles with the same geometry. We anticipate that these PVP-CD complex microneedles are more suitable for vaccine and drug delivery because of their superior properties.

A General Strategy for Ligand Exchange on Upconversion Nanoparticles

Lanthanide-doped upconversion nanoparticles with a suitable surface coating are appealing for biomedical applications. Because high-quality upconversion nanoparticles are typically prepared in an organic solvent and passivated by hydrophobic oleate ligands, a convenient and reliable method for the surface modification of upconversion nanoparticles is thus highly desired to satisfy downstream biological investigations. In this work, we describe a facile and versatile strategy for displacing native oleate ligands on upconversion nanoparticles with a diversity of hydrophilic molecules. The ligand-exchange procedure involves the removal of original oleate ligands followed by the attachment of new ligands in a separate step. The successful coating of relevant ligands was confirmed by Fourier transform infrared spectroscopy, thermogravimetry analysis, and ζ-potential measurement. The surface-modified nanoparticles display high stability and good biocompatibility, as revealed by electron microscopy, photoluminescence spectroscopy, and cytotoxicity assessment. Our study demonstrates that functional biomolecules such as biotin can be directly immobilized on the nanoparticle surface using this approach for the quick and effective detection of streptavidin.

Size Controllable and Surface Tunable Zeolitic Imidazolate Framework-8–Poly(acrylic acid sodium salt) Nanocomposites for pH Responsive Drug Release and Enhanced in Vivo Cancer Treatment

Nanoscale size controllable and surface modifiable zeolitic imidazolate framework-8-poly(acrylic acid sodium salt) (ZIF-8-PAAS) nanocomposites are fabricated by employing PAAS nanospheres as a soft template. These ZIF-8-PAAS nanocomposites have different sizes ranging from 30 to 200 nm and exhibit different crystallinity, and pH sensitivity. These nanocomposites can be employed as vectors to deliver doxorubicin for anticancer therapy, leading to greatly enhanced drug therapeutic efficacy when tested in cell lines and mice model. Systematic toxicity investigation including hematoxylin and eosin staining analysis of tumor and major organs, hematology analysis, and blood chemistry analysis indicates that the nanocomposites possess high biocompatibility. This work provides a strategy to make metal-organic frameworks (MOFs) nanocomposites with size tunability in nanoscale and flexible surface modification for various applications.

Diamond‐Nanoneedle‐Array‐Facilitated Intracellular Delivery and the Potential Influence on Cell Physiology

Vertical arrays of nanostructures can provide access to the cell cytoplasma and probe intracellular molecules. Here, the simple combination of diamond nanoneedle arrays with centrifugation-induced supergravity is shown to efficiently deliver drugs and biomaterials into the cytosol within several minutes, negotiating the endocytososomal system. The potential influence of the technique on cell metabolism is thoroughly studied. By detecting the phosphorylated histone variant H2AX (pH2AX) in the nucleus, it is proved that the operating process will not lead to DNA double-strand breaks. However, the mechanical disruption can temporarily improve the permeability of the cell membranes. Nanoneedle treatment affects cell metabolism at multiple points. The treatment can slightly elevate the apoptotic signal in A549 cells and can significantly increase the production of reactive oxygen species (ROS) in cells, particularly if combined with anticancer drugs. Meanwhile, the activity of cytosolic glucose 6-phosphate dehydrogenase (G6PD) is also raised to counterbalance the elevated ROS content. A detected depolarization of the mitochondrial membrane potential suggests mitochondrial involvement in the intracellular redox reactions and cell apoptosis which are induced by diamond nanoneedle treatment. Overall this study provides a novel understanding on the intracellular delivery mediated by nanoneedles, especially the impact on cell physiology.