Molecule Engineering Metal-Organic Framework-Based Organic Photoelectrochemical Transistor Sensor for Ultrasensitive Bilirubin Detection.

The functionalization of metal-organic frameworks (MOFs) with organic small molecules by in situ postsynthetic modification has garnered considerable attention. However, the precise engineering of recognition sites using this method remains rarely explored in optically controlled bioelectronics. Herein, employing the Schiff base reaction to embed the small molecule (THBA) into a Zr-MOF, we fabricated a hydroxyl-rich MOF on the surface of titanium dioxide nanorod arrays (U6H@TiO NRs) to develop light-sensitive gate electrodes with tailored recognition capabilities.

Activatable NIR Fluorescence Probe for Epinephrine Detection and Bioimaging Based on Anionic Heptamethine Cyanine.

Epinephrine (EP) is an essential catecholamine in the human body. Currently, most EP detection methods are not suitable for in vivo detection due to material limitations. An organic small molecule fluorescent probe based on a chemical cascade reaction for the detection of EP was designed.

A Photoelectrochemical Sensor Based on DNA Bio-Dots-Induced Aggregation of AuNPs for Methionine Detection.

Based on DNA bio-dots-induced aggregation of gold nanoparticles (AuNPs), a methionine (Met) photoelectrochemical (PEC) sensor with CS-GSH-CuNCs/TiO NPs as the photoelectric conversion element and AuNPs as the specific recognition element was constructed. First, a TiO NPs/ITO electrode and CS-GSH-CuNCs were prepared, and then the CS-GSH-CuNCs/TiO NPs/ITO photosensitive electrode was obtained by self-assembly. Next, DNA bio-dots were modified to the upper surface of the electrode using a coupling reaction to assemble the DNA bio-dots/CS-GSH-CuNCs/TiO NPs electrode.

A novel "off-on" ratiometric fluorescent aptasensor for adenosine detection based on FRET between quantum dots and graphene oxide.

A novel "off-on" ratiometric fluorescent aptasensor was established for adenosine detection based on fluorescence resonance energy transfer (FRET) between CdS QDs, DNA QDs as donor and graphene oxide (GO) as acceptor. Amino-riched DNA QDs covalently bonded to the carboxyl group on the edge of the GO, and with the absorption of the TGA-modified CdS QDs with aptamer (CdS QDs-apt) onto the GO surface via the π-π stacking interaction. The fluorescence of both CdS QDs and DNA QDs were efficiently quenched due to FRET (turn off).

An off-on fluorescence aptasensor for trace thrombin detection based on FRET between CdS QDs and AuNPs.

An off-on fluorescence aptasensor was developed for trace thrombin detection based on fluorescence resonance energy transfer (FRET) between CdS QDs and gold nanoparticles (AuNPs). Using DNA pairwise hybridization of the aptamer to the complementary DNA (cDNA), the CdS QDs (energy donor) were tightly coupled to the AuNPs (energy acceptor), resulting in the occurrence of FRET and there was a dramatic fluorescence quenching of CdS QDs (turn off). When the thrombin was added to the fluorescence aptasensor, the specific binding of the aptamer to the target formed a G-quadruplex that caused the AuNPs receptor to detach and the DNA duplex to be disassembled.

Turn-on signal fluorescence sensor based on DNA derived bio-dots/polydopamine nanoparticles for the detection of glutathione.

A convenient, fast, sensitive and highly selective fluorescence sensor for the detection of glutathione (GSH) based on DNA derived bio-dots (DNA bio-dots)/polydopamine (PDA) nanoparticles was constructed. The fluorescent switch of DNA bio-dots was induced to turn off because of fluorescence resonance energy transfer (FRET) reactions between DNA bio-dots and PDA. The presence of GSH blocked the spontaneous oxidative polymerization of dopamine (DA) to PDA, leading the fluorescent switch of DNA bio-dots to be "turned on".

Ascorbic Acid Sensor Based on CdS QDs@PDA Fluorescence Resonance Energy Transfer.

An ascorbic acid (AA) sensor was constructed based on the fluorescence resonance energy transfer (FRET) between CdS quantum dots (CdS QDs) and polydopamine (PDA) to detect trace AA sensitively. FRET occurred due to the broad absorption spectrum of PDA completely overlapped with the narrow emission spectrum of CdS QDs. The fluorescence of CdS QDs was quenched and in the "off" state.

Molecularly Imprinted Silica-Coated CdTe Quantum Dots for Fluorometric Determination of Trace Chloramphenicol.

A dual recognition system with a fluorescence quenching of quantum dots (QDs) and specific recognition of molecularly imprinted polymer (MIP) for the detection of chloramphenicol (CAP) was constructed. MIP@SiO@QDs was prepared by reverse microemulsion method with 3-aminopropyltriethoxysilane (APTS), tetraethyl orthosilicate (TEOS) and QDs being used as the functional monomer, cross-linker and signal sources, respectively. MIP can specifically recognize CAP, and the fluorescence of QDs can be quenched by CAP due to the photo-induced electron transfer reaction between CAP and QDs.

Photoelectrochemical Aptasensors Constructed with Photosensitive PbS Quantum Dots/TiO Nanoparticles for Detection of Kanamycin.

Kanamycin (Kana) is widely used as a veterinary medicine and its abuse causes a serious threat to human health, raising the urgent demand for detection of residual Kana in animal-derived food with high specificity and sensitivity. Here, we developed a photoelectrochemical (PEC) biosensor for rapid quantification of Kana, with lead sulfide quantum dots/titanium dioxide nanoparticles (PbS QDs/TiO NPs) as a photosensitive composite, a Kana-specific DNA aptamer as a functional sensor, and ruthenium(III) hexaammine (Ru(NH)) as a signal booster. To prepare the PEC aptasensor, TiO NPs, PbS QDs, and polyethyleneimine (PEI) were respectively used to modify the indium tin oxide electrode, and then the amine-terminated aptamer probe was connected to the PEI via glutaraldehyde.

A Cu-doped two-dimensional material-based heterojunction photoelectrode: application for highly sensitive photoelectrochemical detection of hydrogen sulfide.

In this work, on the basis of a Cu-doped two-dimensional material-based heterojunction photoelectrode, a novel anodic photoelectrochemical (PEC) sensing platform was constructed for highly sensitive detection of endogenous HS. Briefly, with g-CN and TiO as representative materials, the sensor was fabricated by modifying g-CN/TiO nanorod arrays (NAs) onto the surface of fluorine-doped tin oxide (FTO) and then doping Cu as a Cu S ( = 1, 2) precursor. After the binding of S with surface-attached Cu, the signal was quenched owing to the generation of Cu S which offers trapping sites to hinder generation of photocurrent signals.

Ratiometric pH Sensing and Imaging in Living Cells with Dual-Emission Semiconductor Polymer Dots.

Polymer dots (Pdots) represent newly developed semiconductor polymer nanoparticles and exhibit excellent characteristics as fluorescent probes. To improve the sensitivity and biocompatibility of Pdots ratiometric pH biosensors, we synthesized 3 types of water-soluble Pdots: Pdots-PF, Pdots-PP, and Pdots-PPF by different combinations of fluorescent dyes poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO), poly[(9,9-dioctyl-fluorenyl-2,7-diyl)-co-(1,4-benzo-{2,1',3}-thiadazole)] (PFBT), and fluorescein isothiocyanate (FITC). We found that Pdots-PPF exhibits optimal performance on pH sensing.

Novel fluorescent sensor using molecularly imprinted silica microsphere-coated CdSe@CdS quantum dots and its application in the detection of 2,4,6-trichlorophenol from environmental water samples.

In this study, a high fluorescence sensitivity and selectivity, molecularly imprinted nanofluorescent polymer sensor (MIP@SiO @QDs) was prepared using a reverse microemulsion method. 2,4,6-Trichlorophenol (2,4,6-TCP) was detected using fluorescence quenching. Tetraethyl orthosilicate (TEOS), quantum dots (QDs) and 3-aminopropyltriethoxysilane (APTS) were used as cross-linker, signal sources and functional monomer respectively.

Special Effect of Ionic Liquids on the Extraction of Flavonoid Glycosides from Chrysanthemum morifolium Ramat by Microwave Assistance.

A microwave-assisted extraction approach based on ionic liquids of different chain lengths was successfully applied to the extraction of ten flavonoid glycosides from the flowering heads of Chrysanthemum morifolium Ramat. The pretreated sample was quantified by HPLC-ESI-MSn. The main components were identified as flavonoid glycosides, including three luteolin glycosides, three apigenin glycosides, three kaempferide glycosides, and one acacetin glycoside according to the characteristics of the corresponding CID mass spectrometric patterns.

'Imperfect' conjugated polymer nanoparticles from MEH-PPV for bioimaging and Fe(III) sensing.

A simple and effective method was reported for the preparation from MEH-PPV of conjugated polymer nanoparticles (Pdots) that are water-soluble and well dispersed. The as-prepared Pdots show bright orange fluorescence at a quantum yield up to 32.37%.

Carbon dots as a luminescence sensor for ultrasensitive detection of phosphate and their bioimaging properties.

Highly blue fluorescence carbon dots were synthesized by one-step hydrothermal treatment of potatoes. The as-obtained C-dots have been applied to bioimaging of HeLa cells, which shows their excellent biocompatibility and low cytotoxicity. The results reveal that C-dots are promising for real cell imaging applications.

Formation of fluorescent carbon nanodots from kitchen wastes and their application for detection of Fe(3.).

This work reports a scalable synthesis of water-dispersible fluorescent carbon nanodots based on the simple hydrothermal method (180 °C for 6 h) of kitchen wastes (grape peel for example). We discuss the feasibility of synthesis from kitchen wastes both experimentally and theoretically, and the as-prepared nanodots have high selectivity for Fe(3+) ions based on fluorescence quenching which is due to the complexes between nanodots and metal ions.

Synthesis of highly luminescent mercaptosuccinic acid-coated CdSe nanocrystals under atmospheric conditions.

Here we report a facile one-pot method for the preparation of high-quality CdSe nanocrystals (NCs) in aqueous solution under an air atmosphere. Compared with the traditional use of NaHSe or H2 Se, the more stable sodium selenite is utilized as the Se source for preparing highly luminescent CdSe nanocrystals. By using mercaptosuccinic acid (MSA) as the capping agent and borate-citrate acid as the buffering solution, CdSe nanocrystals with high quantum yield (up to 70%) have been synthesized conveniently.

Molecular rotor-based fluorescent probe for selective recognition of hybrid G-quadruplex and as a K+ sensor.

This work demonstrates the significant fluorescence enhancement of thioflavin T (ThT) when binding to G-quadruplexes possessing hybrid structures by using UV-vis absorption spectra, fluorescence spectra, and Tm experiments to confirm the binding events. ThT binding does not disturb native G-quadruplex structures preformed in Na(+) and K(+) solutions. The fluorescence enhancement is caused by the rotation restriction of benzothiazole (BZT) and dimethylaminobenzene (DMAB) rings in the ThT excited state upon its G-quadruplex binding.

Aqueous synthesis and characterization of TGA-capped CdSe quantum dots at freezing temperature.

CdSe quantum dots (QDs) have traditionally been synthesized in organic phase and then transferred to aqueous solution by functionalizing their surface with silica, polymers, short-chain thiol ligands, or phospholipid micelles. However, a drastic increase in the hydrodynamic size and biotoxicity of QDs may hinder their biomedical applications. In this paper, the TGA-capped CdSe QDs are directly synthesized in aqueous phase at freezing temperature, and they prove to possess high QY (up to 14%).

A gravity driven micro flow injection wetting film extraction system on a polycarbonate chip.

A micro flow injection wetting film liquid-liquid extraction system has been developed for trace analyte concentration and on-chip detection. A hydrophobic channel fabricated on a polycarbonate chip was used to support the wetting film, and hydrostatic pressure generated by the difference in liquid levels was employed to drive the fluids. Sequential injection of segments of aqueous sample solution and organic solvent was conducted by switching the sample- or solvent-containing vials to an on-chip sampling probe, and detection was performed by a co-focused, laser induced fluorescence detector.

Fluorescent core-shell silica nanoparticles as tunable precursors: towards encoding and multifunctional nano-probes.

Core-shell silica nanoparticles comprised of a RuBpy doped silica core and a Pas-DTPA doped silica shell were synthesized and post-functionalized with an encoding fluorescence combination and multiplex imaging function.

Flow injection photochemical spectrofluorimetry for the determination of carbamazepine in pharmaceutical preparations.

Upon on-line photochemical reaction carbamazepine (CBZ) can be converted to a strong fluorescent compound which has a maximum emission wavelength of 478 nm and maximum excitation wavelength of 254 nm. Acidity of reaction medium and the acid type were found to be critical for the on-line photochemically induced fluorescence, dilute hydrochloric acid being the most suitable. Based on these observations, a flow injection photochemical spectrofluorimetric approach for determination of the drug was developed.