Shao Su

Long-Term Antimicrobial Effect of Silicon Nanowires Decorated with Silver Nanoparticles

Silicon nanowires (SiNWs), as a novel one-dimensional semiconducting nanomaterial, are attracting increasing interest in recent years. The synthesis of SiNWs with in situ grown silver nanoparticles (AgNPs) (SiNWs@AgNPs) is reported and the highly effective and long-term antibacterial activity of this novel nanostructure is demonstrated.

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.

Graphene-Based High-Efficiency Surface-Enhanced Raman Scattering-Active Platform for Sensitive and Multiplex DNA Detection

We have developed a surface-enhanced Raman scattering (SERS)-active substrate based on gold nanoparticle-decorated chemical vapor deposition (CVD)-growth graphene and used it for multiplexing detection of DNA. Due to the combination of gold nanoparticles and graphene, the Raman signals of dye were dramatically enhanced by this novel substrate. With the gold nanoparticles, DNA capture probes could be easily assembled on the surface of graphene films which have a drawback to directly immobilize DNA. This platform exhibits extraordinarily high sensitivity and excellent specificity for DNA detection. A detection limit as low as 10 pM is obtained. Importantly, two different DNA targets could be detected simultaneously on the same substrate just using one light source.

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

Gold nanoparticle-decorated MoS2 nanosheets for simultaneous detection of ascorbic acid, dopamine and uric acid

An electrochemical sensor has been developed for simultaneous detection of dopamine (DA), uric acid (UA) and ascorbic acid (AA) based on a gold nanoparticle-decorated MoS2 nanocomposite (AuNPs@MoS2) modified electrode. The AuNPs@MoS2 nanocomposite has been synthesized by electrodeposition of AuNPs on the MoS2 nanosheets, which possesses better properties than pure AuNPs and MoS2. The AuNPs@MoS2 film modified electrode showed excellent electrocatalytic activity toward the oxidation of AA, DA and UA with three well-resolved oxidation peaks. The peak separation of AA–DA, DA–UA and AA–UA is 151 mV, 137 mV and 288 mV, respectively, which permits the modified electrode to individually or simultaneously analyze AA, DA and UA by differential pulse voltammetry (DPV). Under optimum conditions, the AuNPs@MoS2 modified electrode exhibits linear response toward AA, DA and UA in the range of 50–100 000 μM, 0.05–30 μM and 50–40 000 μM, respectively. Moreover, the MoS2-based modified electrode was successfully employed to determine DA in human serum samples with satisfactory results.

Microwave‐Assisted Synthesis of Biofunctional and Fluorescent Silicon Nanoparticles Using Proteins as Hydrophilic Ligands

Protective shell: A microwave-assisted method allows rapid production of biofunctional and fluorescent silicon nanoparticles (SiNPs), which can be used for cell labeling. Such SiNPs feature excellent aqueous dispersibility, are strongly fluorescent, storable, photostable, stable at different pH values, and biocompatible. The method opens new avenues for designing multifunctional SiNPs and related silicon nanostructures.

Nanomaterials-based sensors for applications in environmental monitoring

Nanomaterials are well known to possess excellent electrical, optical, thermal, catalytic properties and strong mechanical strength, which offer great opportunities to construct nanomaterials-based sensors or devices for monitoring environmental contaminations in air, water and soil. Various nanomaterials, such as carbon nanotubes, gold nanoparticles, silicon nanowires and quantum dots, have been extensively explored in detecting and measuring toxic metal ions, toxic gases, pesticides, and hazardous industrial chemicals with high sensitivity, selectivity and simplicity. In the feature article, we reviewed recent advances in this direction, by classifying nanomaterials into five categories to illustrate the applications of nanomaterials in environmental monitoring.

Creating SERS Hot Spots on MoS2 Nanosheets with in Situ Grown Gold Nanoparticles

Herein, a reliable surface-enhanced Raman scattering (SERS)-active substrate has been prepared by synthesizing gold nanoparticles (AuNPs)-decorated MoS2 nanocomposite. The AuNPs grew in situ on the surface of MoS2 nanosheet to form efficient SERS hot spots by a spontaneous redox reaction with tetrachloroauric acid (HAuCl4) without any reducing agent. The morphologies of MoS2 and AuNPs-decorated MoS2 nanosheet were characterized by TEM, HRTEM, and AFM. The formation of hot spots greatly depended on the ratio of MoS2 and HAuCl4. When the concentration of HAuCl4 was 2.4 mM, the as-prepared AuNPs@MoS2-3 nanocomposite exhibited a high-quality SERS activity toward probe molecule due to the generated hot spots. The spot-to-spot SERS signals showed that the relative standard deviation (RSD) in the intensity of the main Raman vibration modes (1362, 1511, and 1652 cm(-1)) of Rhodamine 6G were about 20%, which displayed good uniformity and reproducibility. The AuNPs@MoS2-based substrate was reliable, sensitive, and reproducible, which showed great potential to be an excellent SERS substrate for biological and chemical detection.

Silicon Nanowire-Based Molecular Beacons for High-Sensitivity and Sequence-Specific DNA Multiplexed Analysis

Nanomaterial-based molecular beacons (nanoMBs) have been extensively explored due to unique merits of nanostructures, including gold nanoparticle (AuNP)-, carbon nanotube (CNT)-, and graphene-based nanoMBs. Those nanoMBs are well-studied; however, they possess relatively poor salt stability or low specificity, limiting their wide applications. Here, we present a novel kind of multicolor silicon-based nanoMBs by using AuNP-decorated silicon nanowires as high-performance quenchers. Significantly, the nanoMBs feature robust stability in high-concentration (0.1 M) salt solution and wide-ranging temperature (10-80 °C), high quenching efficiency (>90%) for various fluorophores (e.g., FAM, Cy5, and ROX), and large surfaces for simultaneous assembly of different DNA strands. We further show that silicon-based nanoMBs are highly effective for sensitive and specific multidetection of DNA targets. The unprecedented advantages of silicon-based multicolor nanoMBs would bring new opportunities for challenging bioapplications, such as allele discrimination, early cancer diagnosis, and molecular engineering, etc.