Kelong Ai

Dopamine-Melanin Colloidal Nanospheres: An Efficient Near-Infrared Photothermal Therapeutic Agent for In Vivo Cancer Therapy

Abstract A new generation of photothermal therapeutic agents based on biopolymer dopamine-melanin colloidal nanospheres is described. Benefitting from their naturally wide distribution in humans, dopamine-melanin colloidal nanospheres exhibit robust biocompatibility and biodegradability, and provide up to 40% photothermal conversion efficiency. After administration, they can efficiently damage tumors at low power density and short irradiation time without damaging healthy tissues.

Hydrogen-Bonding Recognition-Induced Color Change of Gold Nanoparticles for Visual Detection of Melamine in Raw Milk and Infant Formula

The color change induced by triple hydrogen-bonding recognition between melamine and a cyanuric acid derivative grafted on the surface of gold nanoparticles can be used for reliable detection of melamine. Since such a color change can be readily seen by the naked eye, the method enables on-site and real-time detection of melamine in raw milk and infant formula even at a concentration as low as 2.5 ppb without the aid of any advanced instruments.

Sp2 C‐Dominant N‐Doped Carbon Sub‐micrometer Spheres with a Tunable Size: A Versatile Platform for Highly Efficient Oxygen‐Reduction Catalysts

A simple, yet versatile strategy to prepare size-controlled and monodisperse carbon sub-micrometer spheres is developed based on the biomolecule dopamine. Unlike traditional carbon materials, the resulting carbon sub-micrometer spheres contain much less sp(3) carbon with high-level electroactive nitrogen. Moreover, metal-carbon hybrid sub-micrometer spheres can be easily obtained, and show highly promising catalytic properties in the oxygen-reduction reaction.

A High-Performance Ytterbium-Based Nanoparticulate Contrast Agent for In Vivo X-Ray Computed Tomography Imaging

X-ray computed tomography (CT) is one of the most widely used imaging procedures in diagnostic medicine due to its many advantages that include cost effectiveness, deep tissue penetration, and high resolution. Currently, small iodinated molecules are routinely used for in vivo contrast enhancement in the clinical setting. Iodinated molecules can effectively absorb X-rays but suffer from short circulation lifetime and potential renal toxicity. Another notable disadvantage is the relatively low K-edge of iodine (33 keV). X-rays that are optimized for this K-edge have a higher potential for damaging tissues. Nanoparticulate CT contrast agents that comprise high atomic number (high-Z) metal elements (mainly focused on gold, platinum, bismuth, and tantalum) have been proved to be a powerful tool to address these issues. These nanoparticulate CT contrast agents have exhibited good imaging effects, acceptable safety profiles, and long circulation half times in vivo. Nevertheless, these metal elements, in principle, would not display prominent superiority in contrast efficacy with respect to clinical iodinated agents under normal operating conditions (120 kVp), because their attenuation characteristics are mismatched with the X-ray photon energy used in clinical CT. Moreover, administration of a large amount of contrast agent is often required in CT imaging, and the very low abundance of these elements in the earth s crust is most likely to result in huge cost issues. Compared to the currently available Au-, Pt-, Bi-, and Tabased nanomaterials, Yb-based nanostructures hold great promise as CT contrast agents. The benefits of Yb in nanomaterials are as follows: 1) its K-edge energy (61 keV) is located just within the higher-energy region of the X-ray spectrum used in clinical CT, hence ensuring both higher intrinsic contrast and lower radiation exposure to the patients; 2) low toxicity when encapsulated in the stable nanoparticle; 3) the highest abundance in the earth s crust among these metals, and thus it has a potential for industrial production; and 4) Yb is a well-known component of upconversion luminescence nanocrystals, which provides a particularly useful platform for the design of multimodal imaging nanoprobes without additional modification of functionalities. Nevertheless, to our knowledge, Yb-based nanoparticulate CT contrast agents have remained unexplored until now. Herein, we describe the first example of Yb-based nanoparticulate CT contrast agents. For these nanoparticles, not only the surface modification but also the control over the size and morphology can be easily achieved. More significantly, owing to the attenuation characteristics of Yb-based nanoparticles, which are matched with the X-ray photon energy used in clinical applications, they can offer a much higher contrast efficacy compared to clinical iodinated agents at 120 kVp. Together with long circulation time and low toxicity, these nanoparticles can act as a high-performance CT contrast agent for in vivo angiography and bimodal imageguided lymph node mapping. Moreover, the near-infrared to visible or near-infrared to near-infrared (NIR-to-Vis or NIRto-NIR) upconversion luminescence of the Yb-nanoparticles can effectively avoid the tissue damage and poor tissue penetration associated with UV excitation. Finally, doping gadolinium into these nanoparticles further endows them with magnetic resonance imaging (MRI) capability. NaYbF4:Er nanoparticles stabilized with oleic acid (OAUCNPs) were synthesized by the strategy schematically illustrated in Figure 1a. These nanoparticles could be welldispersed in many organic solvents without any detectable agglomeration. The transmission electron microscopy (TEM) image showed that undoped NaYbF4:Er nanoparticles were highly monodisperse but had irregular shapes and different sizes (Figure 1b). The control over size and shape of these nanoparticles could be easily achieved through doping Gd ions into these nanoparticles during the synthetic process. Uniformly sized nanoparticles with regular shapes were produced at a Gd concentration of 20 mol% or higher (Figure 1d,e). This control over size and shape of nanoparticles is of great importance in their biological and clinical applications, because the circulation time in vivo and interactions of the nanoparticles with various cells are highly dependent on their size, shape, and surface properties. Furthermore, high-resolution TEM images revealed lattice fringes with a spacing of about 0.31 nm for both the undoped NaYbF4:Er and the 10 mol% Gd-doped samples, corresponding to the lattice spacing in the (111) planes of cubic-phase NaYbF4. For the samples with higher Gd concentrations, the [*] Y. L. Liu, K. L. Ai, Prof. L. H. Lu State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences 5625 Renmin Street, Changchun 130022 (P.R. China) E-mail: lehuilu@ciac.jl.cn

A Superhydrophobic Sponge with Excellent Absorbency and Flame Retardancy

Frequent oil spillages and the industrial discharge of organic solvents have not only caused severe environmental and ecological damage, but also create a risk of fire and explosion. Therefore, it is imperative, but also challenging, to find high-performance absorbent materials that are both effective and less flammable. Here we present a superior superhydrophobic sponge that exhibits excellent absorption performance through a combination of its superhydrophobicity, high porosity, and robust stability. More importantly, it inherits the intrinsic flame-retardant nature of the raw melamine sponge, and is thus expected to reduce the risk of fire and explosion when being used as an absorbent for flammable oils and organic compounds. Moreover, the fabrication of this sponge is easy to scale up, since it does not use a complicated process or sophisticated equipment. These characteristics make the sponge a much more competitive product than the commercial absorbent, nonwoven polypropylene fabric.

Nanoparticulate X-ray Computed Tomography Contrast Agents: From Design Validation to in Vivo Applications

X-ray computed tomography (CT) is one of the most powerful noninvasive diagnostic imaging techniques in modern medicine. Nevertheless, the iodinated molecules used as CT contrast agents in the clinic have relatively short circulation times in vivo, which significantly restrict the applications of this technique in target-specific imaging and angiography. In addition, the use of these agents can present adverse. For example, an adult patient typically receives approximately 70 mL of iodinated agent (350 mg I/mL) because of iodines low contrast efficacy. Rapid renal clearance of such a large dose of these agents may lead to serious adverse effects. Furthermore, some patients are hypersensitive to iodine. Therefore, biomedical researchers have invested tremendous efforts to address these issues. Over the past decade, advances in nanoscience have created new paradigms for imaging. The unique properties of nanomaterials, such as their prolonged circulating half-life, passive accumulation at the tumor sites, facile surface modification, and integration of multiple diverse functions into a single particle, make them advantageous for in vivo applications. However, research on the utilization of nanomaterials for CT imaging has lagged far behind their applications for other imaging techniques such as MRI and fluorescence imaging because of the challenges in the preparation of cost-effective nanoparticulate CT contrast agents with excellent biocompatibility, high contrast efficacy, long in vivo circulation time, and long-term colloidal stability in physiological environments. This Account reviews our recent work on the design and in vivo applications of nanoparticulate CT contrast agents. By optimizing the contrast elements in the nanoparticles according to the fundamental principles of X-ray imaging and by employing the surface engineering approaches that we and others have developed, we have synthesized several nanoparticulate CT contrast agents with excellent imaging performance. For example, a novel Yb-based nanoparticulate agent provides enhanced contrast efficacy compared to currently available CT contrast agents under normal operating conditions. To deal with special situations, we integrated both Ba and Yb with great differential in K-edge value into a single particle to yield the first example of binary contrast agents. This agent displays much higher contrast than iodinated agents at different voltages and is highly suited to diagnostic imaging of various patients. Because of their prolonged in vivo circulation time and extremely low toxicity, these agents can be used for angiography.

Large-Scale Synthesis of Bi(2)S(3) Nanodots as a Contrast Agent for In Vivo X-ray Computed Tomography Imaging

A facile strategy for the large-scale fabrication of Bi(2)S(3) nanodots is presented. Surface modification and control over the size of the nanodots is easily achieved. The as-prepared hydrophilic Bi(2)S(3) nanodots exhibit long in vivo circulation time and, more significantly, a contrast efficacy higher than that of the clinical iodinate agent without any adverse effect.

A novel strategy for making soluble reduced graphene oxide sheets cheaply by adopting an endogenous reducing agent

A facile and efficient strategy is described for the fabrication of soluble reduced graphene oxide (rGO) sheets. Different from the conventional strategies, the proposed method is based on the reduction of graphene oxide by an endogenous reducing agent from a most widely used and cost-effective solvent, without adding any other toxic reducing agent. Simultaneously, this solvent can serve as an effective stabilizer, avoiding complicated and time-consuming modification procedures. The as-prepared rGO sheets not only exhibit high reduction level and conductivity, but also can be well dispersed in many solvents. Of particular significance is that rGO sheets can be produced in large quantities. These advantages endow this proposed synthetic approach great potential applications in the construction of high-performance graphene-based devices at low cost, as demonstrated in our study of NO gas sensing.

Functionalizing Metal Nanostructured Film with Graphene Oxide for Ultrasensitive Detection of Aromatic Molecules by Surface-Enhanced Raman Spectroscopy

Surface-enhanced Raman spectroscopy (SERS) as a powerful analytical tool has gained extensive attention. Despite of many efforts in the design of SERS substrates, it remains a grand challenge for creating a general substrate that can detect diverse target analytes. Herein, we report our attempt to address this issue by constructing a novel metal-graphene oxide nanostructured film as SERS substrate. Taking advantages of the high affinity of graphene oxide (GO) toward aromatic molecules and the SERS property of nanostructured metal, this structure exhibits great potential for diverse aromatic molecules sensing, which is demonstrated by using crystal violet (CV) with positive charge, amaranth with negative charge, and neutral phosphorus triphenyl (PPh(3)) as model molecules.

Fluorescence-enhanced gadolinium-doped zinc oxide quantum dots for magnetic resonance and fluorescence imaging

We report here the development of Gd-doped ZnO quantum dots (QDs) as dual modal fluorescence and magnetic resonance imaging nanoprobes. They are fabricated in a simple, versatile and environmentally friendly method, not only decreasing the difficulty and complexity, but also avoiding the increase of particles size brought about by silica coating procedure in the synthesis of nanoprobes reported previously. These nanoprobes, with exceptionally small size and enhanced fluorescence resulting from the Gd doping, can label successfully the HeLa cells in short time and present no evidence of toxicity or adverse affect on cell growth even at the concentration up to 1 mm. These results show that such nanoprobes have low toxicity, especially in comparison with the traditional PEGylated CdSe/ZnS or CdSe/CdS QDs. In MRI studies, they exert strong positive contrast effect with a large longitudinal relaxivity (r(1)) of water proton of 16 mm(-1) s(-1). Their capability of imaging HeLa cells with MRI implies that they have great potential as MRI contrast agents. Combining the high sensitivity of fluorescence imaging with high spatial resolution of MRI, We expect that the as-prepared Gd-doped Zno QDs can provide a better reliability of the collected data and find promising applications in biological, medical and other fields.