Jia-Hong Wang

Rose-bengal-conjugated gold nanorods for in vivo photodynamic and photothermal oral cancer therapies

Gold nanorods (GNRs) conjugated with rose bengal (RB) molecules exhibit efficient singlet oxygen generation when illuminated by 532 nm green light and high photothermal efficiency under 810 nm near-infrared (NIR) irradiation. In vitro experiments show that reactive oxygen species generated by green light and hyperthermia produced by NIR light constitute two different mechanisms for cancer cell death. The RB-GNRs also exhibit improved photodynamic efficacy by enhancing the uptake of RB by cancer cells. In vivo experiments are conducted on hamster cheek pouches to resemble the human oral cancer conditions more accurately to assess the therapeutic effectiveness. Compared to the single photodynamic therapy (PDT) or photothermal therapy (PTT), the RB-GNRs with combined PDT-PTT capabilities provide better therapeutic effects against oral cancer and have large potential in cancer treatment.

Bimodal optical diagnostics of oral cancer based on Rose Bengal conjugated gold nanorod platform

Early detection of cancer often requires time consuming protocols and expensive instrumentation. To address these limitations, a Rose Bengal conjugated gold nanorod (RB-GNR) platform is developed for optical detection of cancer cells. The GNRs are modified by poly(allylamine hydrochloride) and conjugated with RB molecules to produce RB-GNRs which exhibit strong optical absorption in the near-infrared (NIR) region, good stability in aqueous solution, low cytotoxicity, and high specificity to oral cancer cells. The label-free sensing assay utilizes RB-GNRs as the sensing probe and by monitoring the aggregation-induced red-shift in the NIR absorption wavelength, specific and quantitative analysis of the oral cancer cell lysate is accomplished down to a detection limit of 2000 cells/mL. By employing the RB-GNRs as an imaging probe, an imaging assay is established on a home-made NIR absorption imaging system. Based on the NIR absorption by the RB-GNRs specifically conjugated with the oral cancer cells, multi-channel, rapid and quantitative detection of oral cancer cells is demonstrated. The high sensitivity and specificity of the RB-GNR platform as demonstrated by the two complementary assays provide non-invasive optical diagnostics of oral cancer cells enabling convenient screening and monitoring.

Symmetric and Asymmetric Au–AgCdSe Hybrid Nanorods

This paper describes a facile method for synthesis of Au-AgCdSe hybrid nanorods with controlled morphologies and spatial distributions. The synthesis involved deposition of Ag tips at the ends of Au nanorod seeds, followed by selenization of the Ag tips and overgrowth of CdSe on these sites. By simply manipulating the pH value of the system, the AgCdSe could selectively grow at one end, at both the ends or on the side surface of a Au nanorod, generating a mike-like, dumbbell-like, or toothbrush-like hybrid nanorod, respectively. These three types of Au-AgCdSe hybrid nanorods displayed distinct localized surface plasmon resonance and photoluminescence properties, demonstrating an effective pathway for maneuvering the optical properties of nanocrystals.

One-pot synthesis of CdS–reduced graphene oxide 3D composites with enhanced photocatalytic properties

Nest-like CdS–reduced graphene oxide (CdS–rGO) composites were prepared through a one-pot solvothermal method in which ethylenediamine was used to reduce GO and control the morphology of the CdS, and L-cysteine was used as the sulfur source, reducing agent, and linker between the CdS and rGO. By examining the morphology, structure, and composition of the composites, it could be found that the nest-like CdS particles were decorated on the rGO sheet, and the addition of GO did not influence the crystal structure and shape of the nest-like CdS. Compared with pure CdS, the as-prepared CdS–rGO composites showed enhanced visible light absorption, extended surface area, and facilitated separation of photogenerated charges. Hence, the CdS–rGO composites exhibited improved photocatalytic activity and excellent photostability for the degradation of rhodamine B under visible light irradiation. By combining the good properties of rGO and three-dimensional structured CdS microparticles, the strategy presented in this study is expected to be useful in preparing highly efficient graphene–semiconductor composites for potential applications in various fields.

Metabolizable Ultrathin Bi2Se3 Nanosheets in Imaging-Guided Photothermal Therapy

Poly(vinylpyrrolidone)-encapsulated Bi2 Se3 nanosheets with a thickness of 1.7 nm and diameter of 31.4 nm are prepared by a solution method. Possessing an extinction coefficient of 11.5 L g(-1) cm(-1) at 808 nm, the ultrathin Bi2 Se3 nanosheets boast a high photothermal conversion efficiency of 34.6% and excellent photoacoustic performance. After systemic administration, the Bi2 Se3 nanosheets with the proper size and surface properties accumulate passively in tumors enabling efficient photoacoustic imaging of the entire tumors to facilitate photothermal cancer therapy. In vivo biodistribution studies reveal that they are expelled from the body efficiently after 30 d. The ultrathin Bi2 Se3 nanosheets have large clinical potential as metabolizable near-infrared-triggered theranostic agents.

Black Phosphorus Based Photocathodes in Wideband Bifacial Dye-Sensitized Solar Cells

Ultrasmall black phosphorus quantum dots (BPQDs) serve as the near-infrared light absorber and charge transfer layer in the photocathode of a bifacial n-type dye sensitized solar cell. Wideband light absorption and ≈20% enhancement in the light-to-electron efficiency are accomplished due to the fast carrier transfer and complementary light absorption by the BPQDs demonstrating that BP has large potential in photovoltaics.

Metal‐Ion‐Modified Black Phosphorus with Enhanced Stability and Transistor Performance

Black phosphorus (BP), a burgeoning elemental 2D semiconductor, has aroused increasing scientific and technological interest, especially as a channel material in field-effect transistors (FETs). However, the intrinsic instability of BP causes practical concern and the transistor performance must also be improved. Here, the use of metal-ion modification to enhance both the stability and transistor performance of BP sheets is described. Ag+ spontaneously adsorbed on the BP surface via cation-π interactions passivates the lone-pair electrons of P thereby rendering BP more stable in air. Consequently, the Ag+ -modified BP FET shows greatly enhanced hole mobility from 796 to 1666 cm2 V-1 s-1 and ON/OFF ratio from 5.9 × 104 to 2.6 × 106 . The mechanisms pertaining to the enhanced stability and transistor performance are discussed and the strategy can be extended to other metal ions such as Fe3+ , Mg2+ , and Hg2+ . Such stable and high-performance BP transistors are crucial to electronic and optoelectronic devices. The stability and semiconducting properties of BP sheets can be enhanced tremendously by this novel strategy.

Paper-based plasmonic platform for sensitive, noninvasive, and rapid cancer screening

Surface-enhanced Raman scattering (SERS) fingerprints of individual molecules offer the possibility of multiplexing as well as cancer screening. A highly sensitive, noninvasive, and rapid cancer screening platform encompassing exfoliative cytology and paper-based SERS technology is described. The SERS substrate which consists of plasmonic gold nanorods (GNRs) adsorbed on a piece of filter paper forms the flexible and three-dimensional heterogeneous scaffold for cancer screening. Different and reproducible SERS spectra are obtained from normal and cancerous cells due to specific biomolecular changes in cancerous cells. A diagnostic algorithm based on the ratio of the spectra values is adopted to distinguish between cells exfoliated from 20 normal and cancerous tissues, and a high sensitivity of 100% and specificity of 100% are achieved by I1600/1440 (peak ratio of signals at 1600-1440 cm(-1)) and I1440/1340 (1440-1340 cm(-1)), which is better than I1600/1340 (1600-1340 cm(-1)) with a sensitivity of 70% and specificity of 60%. The combination of exfoliative cytology and paper-based plasmonic technology enables highly sensitive, rapid, and non-invasive cancer screening and has large clinical potential.

Synthesis of gold/rare-earth-vanadate core/shell nanorods for integrating plasmon resonance and fluorescence

The nanoscale core/shell heterostructure is a particularly efficient motif to combine the promising properties of plasmonic materials and rare-earth compounds; however, there remain significant challenges in the synthetic control due to the large interfacial energy between these two intrinsically unmatched materials. Herein, we report a synthetic route to grow rare-earth-vanadate shells on gold nanorod (AuNR) cores. After modifying the AuNR surface with oleate through a surfactant exchange, well-packaged rare-earth oxide (e.g., Gd2O3:Eu) shells are grown on AuNRs as a result of the multiple roles of oleate. Furthermore, the composition of the shell has been altered from oxide to vanadate (GdVO4:Eu) using an anion exchange method. Owing to the carefully designed strategy, the AuNR cores maintain the morphology during the synthesis process; thus, the final Au/GdVO4:Eu core/shell NRs exhibit strong absorption bands and high photothermal efficiency. In addition, the Au/GdVO4:Eu NRs exhibit bright Eu3+ fluorescence with quantum yield as high as ~17%; bright Sm3+ and Dy3+ fluorescence can also be obtained by changing the lanthanide doping in the oxide formation. Owing to the attractive integration of the plasmonic and fluorescence properties, such core/shell heterostructures will find particular applications in a wide array of areas, from biomedicine to energy.

Dual-emitting nanocomposites derived from rare-earth compound nanotubes for ratiometric fluorescence sensing applications

A new class of ratiometric fluorescence sensors composed of rare-earth (RE) compound nanotubes is described. Polyethylenimine-coated yttrium hydroxide fluoride nanotubes (YHF NTs) that were synthesized hydrothermally exhibit highly efficient fluorescence when doped with RE ions. The polyethylenimine on the NTs facilitates the incorporation of phosphors such as quantum dots or organic dyes onto the NT surface to produce dual-emitting nanocomposites which are excellent ratiometric fluorescence sensors. The phosphor layer and underlying tubes in the nanocomposites act as the indicator and reference probes, respectively. This ratiometric fluorescence method which can be applied to the detection of heavy metals in solutions, temperature sensing, and pH sensing boasts high sensitivity and selectivity as well as better accuracy than traditional intensity-based fluorescence methods.