Silicon Nanowire/Polymer Hybrid Solar Cell-Supercapacitor: A Self-Charging Power Unit with a Total Efficiency of 10.5.

An integrated self-charging power unit, combining a hybrid silicon nanowire/polymer heterojunction solar cell with a polypyrrole-based supercapacitor, has been demonstrated to simultaneously harvest solar energy and store it. By efficiency enhancement of the hybrid nanowire solar cells and a dual-functional titanium film serving as conjunct electrode of the solar cell and supercapacitor, the integrated system is able to yield a total photoelectric conversion to storage efficiency of 10.5%, which is the record value in all the integrated solar energy conversion and storage system. This system may not only serve as a buffer that diminishes the solar power fluctuations from light intensity, but also pave its way toward cost-effective high efficiency self-charging power unit. Finally, an integrated device based on ultrathin Si substrate is demonstrated to expand its feasibility and potential application in flexible energy conversion and storage devices.

Highly active and durable methanol oxidation electrocatalyst based on the synergy of platinum-nickel hydroxide-graphene.

Active and durable electrocatalysts for methanol oxidation reaction are of critical importance to the commercial viability of direct methanol fuel cell technology. Unfortunately, current methanol oxidation electrocatalysts fall far short of expectations and suffer from rapid activity degradation. Here we report platinum-nickel hydroxide-graphene ternary hybrids as a possible solution to this long-standing issue. The incorporation of highly defective nickel hydroxide nanostructures is believed to play the decisive role in promoting the dissociative adsorption of water molecules and subsequent oxidative removal of carbonaceous poison on neighbouring platinum sites. As a result, the ternary hybrids exhibit exceptional activity and durability towards efficient methanol oxidation reaction. Under periodic reactivations, the hybrids can endure at least 500,000 s with negligible activity loss, which is, to the best of our knowledge, two to three orders of magnitude longer than all available electrocatalysts.

Highly fluorescent, photostable, and ultrasmall silicon drug nanocarriers for long-term tumor cell tracking and in-vivo cancer therapy.

Silicon nanoparticle (SiNP) nanocarriers feature strong fluorescence, ultrasmall size, robust photostability, and tunable drug-loading capacity. Using SiNP nanocarriers, the first example of long-term cancer cell tracking is successfully demonstrated. Furthermore, in vivo experiments show that tumor-bearing mice treated with SiNP nanocarriers survive over 20 d without observable tumor growth, demonstrating the high-efficacy chemotherapy of the Si nanocarriers.

Specific detection and simultaneously localized photothermal treatment of cancer cells using layer-by-layer assembled multifunctional nanoparticles.

There is a great need to develop multifunctional nanoparticles (MFNPs) for cancer biomarker-based detection and highly selective therapeutic treatment simultaneously. Here we describe a facile approach of layer-by-layer-assembled MFNPs conjugated with monoclonal antibody anti-HER2, demonstrating the specific detection of breast cancer BT474 cells (biomarker HER2 positive) with a high signal-to-noise ratio. The MFNPs contain a well-defined core-shell structure of UCNP@Fe3O4@Au coated by poly(ethylene glycol) (PEG) and anti-HER2 antibody, displaying excellent dispersity in various aqueous solutions. This unique combination of nanoparticles and ligand molecules allows us to perform photothermal treatment (PTT) of the cancer cells, while simultaneously quantifying the distribution of MFNPs on a cancer cell surface induced by antigen-antibody binding events. An important finding is that cancer cells adjacent to each other or in physical proximity within micrometers may end up with different fates of survival or death in PTT. This dramatic difference is determined by the antigen-antibody binding events at the interface of MFNPs and cells because of tumor cell heterogeneity. Therefore, our experiments reveal a new scale of the highly localized feature of the photothermal effect at the single-cell level illuminated by a continuous-wave near-IR laser.

Silicon nanomaterials platform for bioimaging, biosensing, and cancer therapy.

Silicon nanomaterials are an important class of nanomaterials with great potential for technologies including energy, catalysis, and biotechnology, because of their many unique properties, including biocompatibility, abundance, and unique electronic, optical, and mechanical properties, among others. Silicon nanomaterials are known to have little or no toxicity due to favorable biocompatibility of silicon, which is an important precondition for biological and biomedical applications. In addition, huge surface-to-volume ratios of silicon nanomaterials are responsible for their unique optical, mechanical, or electronic properties, which offer exciting opportunities for design of high-performance silicon-based functional nanoprobes, nanosensors, and nanoagents for biological analysis and detection and disease treatment. Moreover, silicon is the second most abundant element (after oxygen) on earth, providing plentiful and inexpensive resources for large-scale and low-cost preparation of silicon nanomaterials for practical applications. Because of these attractive traits, and in parallel with a growing interest in their design and synthesis, silicon nanomaterials are extensively investigated for wide-ranging applications, including energy, catalysis, optoelectronics, and biology. Among them, bioapplications of silicon nanomaterials are of particular interest. In the past decade, scientists have made an extensive effort to construct a silicon nanomaterials platform for various biological and biomedical applications, such as biosensors, bioimaging, and cancer treatment, as new and powerful tools for disease diagnosis and therapy. Nonetheless, there are few review articles covering these important and promising achievements to promote the awareness of development of silicon nanobiotechnology. In this Account, we summarize recent representative works to highlight the recent developments of silicon functional nanomaterials for a new, powerful platform for biological and biomedical applications, including biosensor, bioimaging, and cancer therapy. First, we show that the interesting photoluminescence properties (e.g., strong fluorescence and robust photostability) and excellent biocompatibility of silicon nanoparticles (SiNPs) are superbly suitable for direct and long-term visualization of biological systems. The strongly fluorescent SiNPs are highly effective for bioimaging applications, especially for long-term cellular labeling, cancer cell detection, and tumor imaging in vitro and in vivo with high sensitivity. Next, we discuss the utilization of silicon nanomaterials to construct high-performance biosensors, such as silicon-based field-effect transistors (FET) and surface-enhanced Raman scattering (SERS) sensors, which hold great promise for ultrasensitive and selective detection of biological species (e.g., DNA and protein). Then, we introduce recent exciting research findings on the applications of silicon nanomaterials for cancer therapy with encouraging therapeutic outcomes. Lastly, we highlight the major challenges and promises in this field, and the prospect of a new nanobiotechnology platform based on silicon nanomaterials.

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.

Noble metal coated single-walled carbon nanotubes for applications in surface enhanced Raman scattering imaging and photothermal therapy.

Single-walled carbon nanotubes (SWNTs) with various unique optical properties are interesting nanoprobes widely explored in biomedical imaging and phototherapies. Herein, DNA-functionalized SWNTs are modified with noble metal (Ag or Au) nanoparticles via an in situ solution phase synthesis method comprised of seed attachment, seeded growth, and surface modification with polyethylene glycol (PEG), yielding SWNT-Ag-PEG and SWNT-Au-PEG nanocomposites stable in physiological environments. With gold or silver nanoparticles decorated on the surface, the SWNT-metal nanocomposites gain an excellent concentration and excitation-source dependent surface-enhanced Raman scattering (SERS) effect. Using a near-infrared (NIR) laser as the excitation source, targeted Raman imaging of cancer cells labeled with folic acid (FA) conjugated SWNT-Au nanocomposite (SWNT-Au-PEG-FA) is realized, with images acquired in significantly shortened periods of time as compared to that of using nonenhanced SWNT Raman probes. Owing to the strong surface plasmon resonance absorption contributed by the gold shell, the SWNTs-Au-PEG-FA nanocomposite also offers remarkably improved photothermal cancer cell killing efficacy. This work presents a facile approach to synthesize water-soluble noble metal coated SWNTs with a strong SERS effect suitable for labeling and fast Raman spectroscopic imaging of biological samples, which has been rarely realized before. The SWNT-Au-PEG nanocomposite developed here may thus be an interesting optical theranostic probe for cancer imaging and therapy.

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.

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.

Multifunctional nanoparticles for upconversion luminescence/MR multimodal imaging and magnetically targeted photothermal therapy.

Theranostics, the combination of diagnostics and therapies, has become a new concept in the battles with various major diseases such as cancer. Herein, we develop multifunctional nanoparticles (MFNPs) with highly integrated functionalities including upconversion luminescence, superparamagnetism, and strong optical absorption in the near-infrared (NIR) region with high photostability. In vivo dual modal optical/magnetic resonance imaging of mice uncovers that by placing a magnet nearby the tumor, MFNPs tend to migrate toward the tumor after intravenous injection and show high tumor accumulation, which is ~8 folds higher than that without magnetic targeting. NIR laser irradiation is then applied to the tumors grown on MFNP-injected mice under magnetic tumor-targeting, obtaining an outstanding photothermal therapeutic efficacy with 100% of tumor elimination in a murine breast cancer model. We present here a strategy for multimodal imaging-guided, magnetically targeted physical cancer therapy and highlight the promise of using multifunctional nanostructures for cancer theranostics.

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.

Optimization of surface chemistry on single-walled carbon nanotubes for in vivo photothermal ablation of tumors.

Carbon nanotubes have shown great potential in various areas of biomedicine. Herein, we synthesize a series of amphiphilic polymers by anchoring polyethylene glycol (PEG) of different lengths at various densities on poly(maleic anhydride-alt-1-octadecene) (PMHC(18)). The blood circulation and biodistribution of those PEG-PMHC(18)-coated SWNTs in mice after intravenous injection are measured by an established Raman spectroscopy method. It is found that heavily PEGylated SWNTs with ultra-long blood circulation half-lives, although shows high uptake in the tumor, tend to accumulate in the skin dermis. A surface coating which affords SWNTs a blood half-life of 12-13 h appears to be optimal to balance the tumor-to-normal organ (T/N) uptake ratios of nanotubes in major organs. Using the selected SWNT conjugate, we then carry out a pilot in vivo photothermal therapy study and observe a promising cancer treatment efficacy. Our results highlight the importance of surface coating to the in vivo behaviors of nanomaterials in general and could provide guidelines to the future design of SWNT bioconjugates for various in vivo applications.

Graphene in mice: ultrahigh in vivo tumor uptake and efficient photothermal therapy.

Although biomedical applications of carbon nanotubes have been intensively studied in recent years, its sister, graphene, has been rarely explored in biomedicine. In this work, for the first time we study the in vivo behaviors of nanographene sheets (NGS) with polyethylene glycol (PEG) coating by a fluorescent labeling method. In vivo fluorescence imaging reveals surprisingly high tumor uptake of NGS in several xenograft tumor mouse models. Distinctive from PEGylated carbon nanotubes, PEGylated NGS shows several interesting in vivo behaviors including highly efficient tumor passive targeting and relatively low retention in reticuloendothelial systems. We then utilize the strong optical absorbance of NGS in the near-infrared (NIR) region for in vivo photothermal therapy, achieving ultraefficient tumor ablation after intravenous administration of NGS and low-power NIR laser irradiation on the tumor. Furthermore, no obvious side effect of PEGylated NGS is noted for the injected mice by histology, blood chemistry, and complete blood panel analysis in our pilot toxicity study. Although a lot more efforts are required to further understand the in vivo behaviors and the long-term toxicology of this new type of nanomaterials, our work is the first success of using carbon nanomaterials for efficient in vivo photothermal therapy by intravenous administration and suggests the great promise of graphene in biomedical applications, such as cancer treatment.

A novel colorimetric and fluorescent anion chemosensor based on the flavone quasi-crown ether-metal complex.

The metal-ligand complex 1 ([Mg (L)] (2+)) (or 2 ([Ca (L)]( 2+))) was demonstrated to selectively bind HSO(4)(-) (or H(2)PO(4)(-)) over other anions by using UV-vis absorption and fluorescence spectroscopy. The studied complex exhibits the remarkable color change and fluorescence quenching upon introducing HSO(4)(-) (or H(2)PO(4)(-)) anion in acetonitrile. Both the mechanism and structure of the secondary complex of complex 1 with anion were proposed on the basis of theoretical computation.