Jun Jie Zhu

Rapid sonochemical synthesis of highly luminescent non-toxic AuNCs and Au@AgNCs and Cu (II) sensing

Highly fluorescent and water-soluble gold nanoclusters (AuNCs) with near-infrared-emission and Au@AgNCs with yellow-emission were successfully prepared via a rapid sonochemical approach, and the as-prepared AuNCs could be applied in the determination of Cu(2+) with a wider detection range and lower detection limit.

DNA‐Hybrid‐Gated Multifunctional Mesoporous Silica Nanocarriers for Dual‐Targeted and MicroRNA‐Responsive Controlled Drug Delivery

The design of an ideal drug delivery system with targeted recognition and zero premature release, especially controlled and specific release that is triggered by an exclusive endogenous stimulus, is a great challenge. A traceable and aptamer-targeted drug nanocarrier has now been developed; the nanocarrier was obtained by capping mesoporous silica-coated quantum dots with a programmable DNA hybrid, and the drug release was controlled by microRNA. Once the nanocarriers had been delivered into HeLa cells by aptamer-mediated recognition and endocytosis, the overexpressed endogenous miR-21 served as an exclusive key to unlock the nanocarriers by competitive hybridization with the DNA hybrid, which led to a sustained lethality of the HeLa cells. If microRNA that is exclusively expressed in specific pathological cell was screened, a combination of chemotherapy and gene therapy should pave the way for a targeted and personalized treatment of human diseases.

Fabrication of near-infrared-emitting CdSeTe/ZnS core/shell quantum dots and their electrogenerated chemiluminescence

New water-soluble CdSeTe/ZnS core-shell quantum dots with excellent near-infrared emission were synthesized via an aqueous solution method; they showed strong electrogenerated chemiluminescence and favorable biocompatibility.

Ultrasensitive Cu2+ sensing by near-infrared-emitting CdSeTe alloyed quantum dots.

The near-infrared (NIR)-emitting CdSeTe alloyed quantum dots (AQdots) that capped with L-cysteine were applied for ultrasensitive Cu(2+) sensing. The sensing approach was based on the fluorescence of the AQdots selectively quenched in the presence of Cu(2+). Experimental results showed a low interference response towards other metal ions. The possible quenching mechanism was discussed on the basis of the binding between L-cysteine and the metal ions. In addition, biomolecules have low effect on the fluorescence due to the minimized interferences in NIR region. The response of the NIR optical sensor was linearly proportional to the concentration of Cu(2+) ranging from 2 x 10(-8) to 2 x 10(-6) mol L(-1). Furthermore, it has been successfully applied to the detection of Cu(2+) in vegetable samples.

Rhodamine B derivative-functionalized upconversion nanoparticles for FRET-based Fe3+-sensing

A novel fluorescence resonance energy transfer (FRET)-based probe, γ-cyclodextrin modified oleic acid-NaYF4:Yb, Ho upconversion nanoparticles functionalized with a rhodamine B derivative (RBD), has been achieved for Fe(3+)-sensing in aqueous solution with high sensitivity and selectivity.

Fabrication of a boron nitride–gold nanocluster composite and its versatile application for immunoassays

A multifunctional boron nitride-gold nanocluster composite was fabricated using poly-diallyldimethylammonium chloride as a stabilizer and a linker. The as-fabricated composite could be used as a fluorescent or an electrochemical label for immunosensing in the sensitive detection of interleukin-6.

Excitation wavelength dependence of the visible photoluminescence from amorphous ZnO granular films

Amorphous ZnO granular films were fabricated by anodizing zinc sheet in 0.5M oxalic acid solution under direct current voltage. The photoluminescence spectrum of the as-anodized sample shows a very broad visible emission band, which can be Gaussian divided into two subbands at 525 and 600nm. Based on their annealing behavior and the growing mechanism of the ZnO films, the two subbands are attributed to optical transitions in oxygen vacancies and oxygen interstitials, respectively. Obvious redshifts of the two subbands were observed with increasing excitation wavelength. Spectral analyses suggest that the excitation wavelength dependences of the two subbands are due to the quantum confinement on the amorphous ZnO nanoparticles mainly with sizes of ∼10nm. This work provides a good understanding of the photoluminescence behavior of amorphous ZnO particles.

Near‐Infrared Photothermally Activated DNAzyme–Gold Nanoshells for Imaging Metal Ions in Living Cells

DNAzymes have enjoyed success as metal ion sensors outside cells. Their susceptibility to metal-dependent cleavage during delivery into cells has limited their intracellular applications. To overcome this limitation, a near-infrared (NIR) photothermal activation method is presented for controlling DNAzyme activity in living cells. The system consists of a three-stranded DNAzyme precursor (TSDP), the hybridization of which prevents the DNAzyme from being active. After conjugating the TSDP onto gold nanoshells and upon NIR illumination, the increased temperature dehybridizes the TSDP to release the active DNAzyme, which then carries out metal-ion-dependent cleavage, resulting in releasing the cleaved product containing a fluorophore. Using this construct, detecting Zn2+ in living HeLa cells is demonstrated. This method has expanded the DNAzyme versatility for detecting metal ions in biological systems under NIR light that exhibits lower phototoxicity and higher tissue penetration ability.

3.08 – Preparation and Analytical Applications of Quantum Dots

This chapter presents a general description of the preparation of quantum dots and their analytical application with optical and electrochemical assays, including fluorescence, reversible optics, electrochemiluminescence (ECL), cyclic voltammetry (CV), differential pulse voltammetry (DPV), and square wave voltammetry (SWV). It contains four main sections with the preparation of QDs, the fluorescent application, the ECL application, and the electrochemical application in inorganic substance analysis, organics analysis, immunoassay, and aptasensor.