Nano LIFE

Optical imaging uses nonionizing radiation to obtain images of tissues and cells inside the body. The approach reduces exposure to harmful radiation and is suitable for lengthy and repetitive imaging procedures. Development of strongly fluorescent imaging agents will help in the detection of signal through thick tissues. Presence of such biocompatible imaging agent has potential clinical applications as it gives real-time information on disease progression and therapeutic response. We report here a nanoformulation-based strategy to synthesize a strongly fluorescent imaging agent. The fabrication procedure uses silica nanocapsules (SNC) to trap and concentrate highly fluorescent Coumarin 545T fluorophore. Biocompatibility of synthesized SNC–Coumarin was tested in cell lines and zebrafish. In vivo detection of fluorescent signal was validated in optically translucent zebrafish larvae and adult casper mutant. Nonbiased labeling of all cell types was detected in both young and adult zebrafish. The ability to differentiate fluid filled cavities from cells was also highlighted during in vivo imaging. Concomitant assessment of internalized SNC–Coumarin through acquired fluorescent intensity and associated biocompatibility in zebrafish supports its use as an in vivo imaging agent.

A high percentage of developed drug compounds are poorly soluble in water, which severely limits their applications. Nanotechnology has been used to address this issue. Here we describe a simple and versatile bottom-up approach for the preparation of drug nanostructures by surface solvent evaporation on aluminum surface and polymer-coated surface. Three poorly water soluble drug compounds, including griseofulvin (GF), curcumin and antimalarial compound SL-2-25 have been investigated as model compounds. The structures are mainly characterized by scanning electronic microscopy (SEM) while the GF nanoparticles are also examined by powder X-ray diffraction (PXRD) and thermogravimetric analysis (TGA). A variety of structures including microassemblies composed of nanoparticles, nanospheres and nanofibers have been produced. A sonication method can be employed to produce aqueous nanoparticle suspension.

A new type of Cy5-encapsulated photostable fluorescent silica nanoparticles (FSNPs) bearing positive charges have been successfully fabricated by a reverse microemulsion synthesis in one-pot. The Cy5 dye containing four primary amines are embedded into silica via covalent bonds through a silane coupling agent (GPTMS), followed by co-condensation with tetraethylorthosilicate. The uniform-sized, spherical and monodispersed FSNPs have high fluorescence intensity and photostability. The FSNPs exhibit high stability, good biocompatibility as well as low cytotoxicity. These FSNPs can be internalized into live cells and thus fluorescently label the cells. This study provides a simple synthesis approach that can be applied to other water-soluble and amino-modified organic dye molecules for biological targeting and fluorescent cell imaging.

The adsorption of three kinds of azo dyes from aqueous solution on HKUST-1/graphene oxide (GO) composite was studied in view of the removal efficiency, adsorption isotherm, and regenerate of the sorbent. HKUST-1/GO was found to be with higher dyes removal efficiency than HKUST-1. All the adsorption isotherms of azo dyes on HKUST-1/GO composite followed Freundlich isotherm. The adsorbed azo dyes on HKUST-1/GO could be eluted by acetone, so HKUST-1/GO can also be used for enrichment of azo dyes as adsorbent.

A composite of chromium (III) terephthalate metal-organic framework and graphene oxide (MIL-101/GO) coated stir bar was prepared by sol–gel technique for the first time and was employed for stir bar sorptive extraction (SBSE) of trace azo dyes amaranth, sunset yellow and carmine from water samples followed by UV–Vis spectrophotometric detection. A MIL-101/GO coating was first created on the glass bar surface. MIL-101/GO and MIL-101/GO coated stir bars were characterized. The enrichment factors of azo dyes by SBSE have been investigated in detail, and the optimized experimental parameters were obtained. Under the optimal conditions, a method for determination of trace amount of azo dyes was setup, and the detection limits of amaranth, sunset yellow and carmine were 2.3 ng/mL, 1.7 ng/mL and 1.6 ng/mL. The proposed method was successfully applied for the analysis of the three azo dyes in water samples.

The adsorption of malachite green from an aqueous solution of magnetic Fe₃O₄ was studied in view of the adsorption isotherm, kinetics and regeneration of the sorbent. The adsorption isotherm of MG on nano-Fe₃O₄ composite followed the Langmuir isotherm. Adsorption kinetics was determined from the experimental data. The nano-Fe₃O₄ can be recycled for reuse after regeneration through acetonitrile. The high adsorption capacity and excellent reusability made Fe₃O₄ attractive for the removal of MG from aqueous solution.

An effective method for rapid and high efficiency removal of Polycyclic aromatic hydrocarbons from contaminated water had been proposed based on the Graphene/silica magnetic nanocomposites (M/GO). Factors affecting the adsorption efficiency of M/GO were investigated and we found that the optimum adsorption pH was 5.5, adsorption time was 20 min and adsorbent concentration was 400 mg⋅L^-1 for phenanthrene and 1200 mg⋅L^-1 for pyrene, respectively. The adsorption mechanisms were also discussed. The regeneration and reuse experiments showed good reusability of the as-prepared adsorbent. In addition, this method was successfully applied to the rapid and high efficiency removal of phenanthrene and pyrene from real water samples, which presages more opportunities for application in environment and material sciences.

Gold nanoparticles (AuNPs) as one of the most stable metal nanoparticles have demonstrated extensive applications in recent years. In this review, the synthetic methods to AuNPs were discussed, which included citrate reduction, Brust–Schiffrin method, ligand-stabilized AuNPs and so on, followed with the synthetic mechanisms. Special emphasis was made on polymer modified AuNPs in biomedical applications, especially for polymer/AuNPs conjugated in the field of cancer therapy and early diagnosis. The applications based on optoelectronic properties, which was related to surface plasmon resonance (SPR) effect, were also summarized as biosensors for labeling and detection.