Yimei Lu

One-pot microwave synthesis of water-dispersible, ultraphoto- and pH-stable, and highly fluorescent silicon quantum dots.

Fluorescent silicon quantum dots (SiQDs) are facilely prepared via one-pot microwave-assisted synthesis. The as-prepared SiQDs feature excellent aqueous dispersibility, robust photo- and pH-stability, strong fluorescence, and favorable biocompatibility. Experiments show the SiQDs are superbly suitable for long-term immunofluorescent cellular imaging. Our results provide a new and invaluable methodology for large-scale synthesis of high-quality SiQDs, which are promising for various optoelectronic and biological applications.

In vivo distribution, pharmacokinetics, and toxicity of aqueous synthesized cadmium-containing quantum dots

Fluorescent Ⅱ-Ⅳ Quantum dots (QDs) have demonstrated to be highly promising biological probes for various biological and biomedical applications due to their many attractive merits, such as robust photostabilty, strong photoluminescence, and size-tunable fluorescence. Along with wide ranging bioapplications, concerns about their biosafety have attracted increasingly intensive attentions. In comparison to full investigation of in vitro toxicity, there has been only scanty information regarding in vivo toxicity of the QDs. Particularly, while in vivo toxicity of organic synthesized QDs (orQDs) have been investigated recently, there exist no comprehensive studies concerning in vivo behavior of aqueous synthesized QDs (aqQDs) up to present. Herein, we investigate short- and long-term in vivo biodistribution, pharmacokinetics, and toxicity of the aqQDs. Particularly, the aqQDs are initially accumulated in liver after short-time (0.5-4 h) post-injection, and then are increasingly absorbed by kidney during long-time (15-80 days) blood circulation. Moreover, obviously size-dependent biodistribution is observed: aqQDs with larger sizes are more quickly accumulated in the spleen. Furthermore, histological and biochemical analysis, and body weight measurement demonstrate that there is no overt toxicity of aqQDs in mice even at long-time exposure time. Our studies provide invaluable information for the design and development of aqQDs for biological and biomedical applications.

Gold Nanoparticles-Decorated Silicon Nanowires as Highly Efficient Near-Infrared Hyperthermia Agents for Cancer Cells Destruction

Near-infrared (NIR) hyperthermia agents are of current interest because they hold great promise as highly efficacious tools for cancer photothermal therapy. Although various agents have been reported, a practical NIR hyperthermia agent is yet unavailable. Here, we present the first demonstration that silicon nanomaterials-based NIR hyperthermia agent, that is, gold nanoparticles-decorated silicon nanowires (AuNPs@SiNWs), is capable of high-efficiency destruction of cancer cells. AuNPs@SiNWs are found to possess strong optical absorbance in the NIR spectral window, producing sufficient heat under NIR irradiation. AuNPs@SiNWs are explored as novel NIR hyperthermia agents for photothermal ablation of tumor cells. In particular, three different cancer cells treated with AuNPs@SiNWs were completely destructed within 3 min of NIR irradiation, demonstrating the exciting potential of AuNPs@SiNWs for NIR hyperthermia agents.

Water‐Dispersed Near‐Infrared‐Emitting Quantum Dots of Ultrasmall Sizes for In Vitro and In Vivo Imaging

Near-infrared (NIR)-fluorescence imaging is widely recognized as an effective method for high-resolution and highsensitivity bioimaging because of its minimized biological autofluorescence background and the increased penetration of excitation and emission light through tissues in the NIR wavelength window (700–900 nm). There have been tremendous efforts to develop high-efficiency fluorescent biological probes for NIR-fluorescence imaging. Semiconductor quantum dots (QDs) have attracted much recent attention as a new generation of fluorescent probes because of their unique optical properties such as strong luminescence, high photostability, and size-tunable emission wavelength. While QDs emitting in the range of 450–650 nm have been well developed, NIR-emitting QDs have been much less explored because of their relatively complicated synthesis and post-treatment manipulations. Furthermore, NIR-emitting QDs are usually prepared in organic phase, and additional surface modification is employed to render them waterdispersible for biological applications. The relatively complicated surface modification often results in an increase in size of the QDs. Only recently, water-dispersed NIRemitting CdTe/CdS QDs with tetrahedral structure were directly prepared in aqueous phase through the epitaxialshell-growth method. Despite these advances, much work is still needed to obtain NIR-emitting QDs that can be facilely synthesized in aqueous phase for high-sensitivity and specific bioimaging. Herein, we report the first example of ultrasmall-sized NIR-emitting CdTe QDs with excellent aqueous dispersibility, robust storage, chemical, and photostability, and strong photoluminescence (photoluminescent quantum yield (PLQY): 15–20%). Significantly, the NIR QDs are directly synthesized in aqueous phase through a facile one-step microwave-assisted method (see the Supporting Information for experimental details and mechanisms) by utilizing several attractive properties of microwave irradiation such as prompt startup, easy heat control (on and off), prompt and homogeneous heating, and so forth. More importantly, highly spectrally and spatially resolved bioimaging was possible, and efficient tumor passive targeting in live mice was shown by using the prepared QDs. QDs with different emission wavelengths in the NIR range (lmax= 700–800 nm) can be readily prepared through fine adjustment of the experimental conditions (e.g., reaction time and temperature). Figure 1a,b displays the normalized ultraviolet photoluminescence (UV-PL) spectra for a series of as-prepared QDs with controllable maximum emission wavelength ranging from 700 to 800 nm in aqueous solution. Such QD solutions are transparent under ambient light conditions, suggesting the as-prepared QDs are well-dispersed in aqueous phase without further treatment (Figure 1c). The excellent aqueous dispersibility of the QDs arises from the surfacecovering mercaptopropionic acid (MPA) that acts as a stabilizer because of the presence of negatively charged carboxylic groups. Under UV irradiation the fluorescence of the as-prepared QDs became darker and the emission wavelength gradually shifted out of the visible region (Figure 1d). The transmission electron microscopy (TEM) and highresolution TEM (HRTEM) images reveal that the NIRemitting QDs are spherical particles with good monodispersibility (Figure 2a,b). The existence of a well-resolved crystal lattice in the HRTEM image further confirms the highly crystalline structures of the QDs (Figure 2b inset). Furthermore, the size distribution histogram (Figure 2c), which was determined by measuring more than 250 particles, shows that the average size and standard deviation of the as-prepared NIR-emitting QDs is (3.74 0.67) nm. Comparatively, the [*] Prof. Y. He, Y. L. Zhong, Dr. Y. Y. Su, Y. M. Lu, Z. Y. Jiang, F. Peng, T. T. Xu, Dr. S. Su Institute of Functional Nano & Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University Suzhou, Jiangsu 215123 (China) Fax: (+86)512-6588-2846 E-mail: yaohe@suda.edu.cn

Peptide-Conjugated Fluorescent Silicon Nanoparticles Enabling Simultaneous Tracking and Specific Destruction of Cancer Cells

We herein introduce a kind of fluorescent silicon nanoparticles (SiNPs) bioprobes, that is, peptides-conjugated SiNPs, which simultaneously feature small sizes (<10 nm), biological functionality, and stable and strong fluorescence (photoluminescent quantum yield (PLQY): ∼28%), as well as favorable biocompatibility. Taking advantage of these merits, we further demonstrate such resultant SiNPs bioprobes are superbly suitable for real-time immunofluorescence imaging of cancer cells. Meanwhile, malignant tumor cells could be specifically destroyed by the peptides-conjugated SiNPs, suggesting potential promise of simultaneous detection and treatment of cancer cells.

Photostable water-dispersible NIR-emitting CdTe/CdS/ZnS core–shell–shell quantum dots for high-resolution tumor targeting

Near-infrared (NIR, 700-900 nm) fluorescent quantum dots are highly promising as NIR bioprobes for high-resolution and high-sensitivity bioimaging applications. In this article, we present a class of NIR-emitting CdTe/CdS/ZnS core-shell-shell quantum dots (QDs), which are directly prepared in aqueous phase via a facile microwave synthesis. Significantly, the prepared NIR-emitting QDs possess excellent aqueous dispersibility, strong photoluminescence, favorable biocompatibility, robust storage-, chemical-, and photo-stability, and finely tunable emission in the NIR range (700-800 nm). The QDs are readily functionalized with antibodies for use in immunofluorescent bioimaging, yielding highly spectrally and spatially resolved emission for in vitro and in vivo imaging. In comparison to the large size of 15-30 nm of the conventional NIR QDs, the extremely small size (≈ 4.2 nm or 7.5 nm measured by TEM or DLS, respectively) of our QDs offers great opportunities for high-efficiency and high-sensitivity targeted imaging in cells and animals.

In vivo behavior of near infrared-emitting quantum dots.

Near-infrared (NIR, 700-900 nm) fluorescent nanomaterials-based probes have shown major impacts on high-resolution and high-sensitivity bioimaging applications. Typically, NIR-emitting quantum dots (QDs) are highly promising as NIR bioprobes due to their unique optical properties. However, NIR-emitting QDs-related in vivo behavior remains unknown at present, severely limiting their wide-ranging bioapplications. Herein, we investigate short- and long-term in vivo biodistribution, pharmacokinetics, and toxicity of the NIR-emitting QDs. Particularly, we reveal that the NIR-emitting QDs are initially accumulated in liver, spleen, and lung for short-time (0.5-4 h) post-injection, and then increasingly absorbed by kidney during long-time (4-94 days) blood circulation. Obviously time-dependent biodistribution is observed: with time continues, most of NIR-emitting QDs are finally accumulated in liver and kidney; comparatively, less NIR-emitting QDs are observed in spleen, lung, and bone marrow. Furthermore, histological and biochemical analyses, and body weight measurements demonstrate that there is no overt toxicity of NIR-emitting QDs in mice even at long-time (94 days) exposure time. Our studies provide invaluable information for the design and development of NIR-emitting QDs-based nanoprobes for biological and biomedical applications.

A silicon-based antibacterial material featuring robust and high antibacterial activity

In this article, we present a kind of silicon-based antibacterial material made of silver nanoparticle (AgNP)-decorated silicon wafers (AgNP@Si), which is facilely and rapidly (30 min) synthesized via a one-step reaction. Significantly, such a resultant silicon-based antibacterial material features stable and high antibacterial activity, preserving >99% antibacterial efficiency against E. coli during 30 day storage.

Silicon nanowire-based therapeutic agents for in vivo tumor near-infrared photothermal ablation

The first example of silicon nanowire (SiNW)-based in vivo tumor phototherapy is presented. Gold nanoparticle (AuNP)-decorated SiNWs are employed as high-performance NIR hyperthermia agents for highly efficacious in vivo tumour ablation. Significantly, the overall survival time of SiNW-treated mice is drastically prolonged, with 100% of mice being alive and tumor-free for over 8 months, which is the longest survival time ever reported for tumor-bearing mice treated with nanomaterial-based NIR hyperthermia agents.