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We present herein a new facile solution-phase route to the growth of high crystalline quality Cu 2 SnSe 3 (CTSe) thin film on a conductive substrate and demonstrate for the first time its promising application as an efficient counter electrode (CE) in liquid-junction quantum dot-sensitized solar cells (QDSCs). Dissolving Cu 2 Se and SnSe powders in the thiol-amine mixture forms a homogeneous CTSe molecular precursor solution. High-quality crystalline CTSe thin film electrode can be readily deposited from the above solution via a low-temperature heating step. Powder X-ray diffraction experiment combined with Raman spectroscopy revealed that the resulting CTSe has the monoclinic crystal structure. Electrochemical measurements, impedance spectroscopy, Tafel polarization, and cyclic voltammetry verified that CTSe possesses fascinating electrocatalytic activity for S 2− / S n 2 − redox couple in aqueous polysulfide electrolyte solution, and is superior to the traditional electrocatalyst, Pt, both in catalytic activity and in electrochemical stability under prolonged potential cycling, rationalizing the improved solar cell device performance, i.e., QDSCs employing CTSe CE showed more than a two-fold improvement in power conversion efficiency relative to that of Pt-based cells. The excellent catalytic performance along with the ease of solution processing of these earth-abundant CTSe materials make them a distinctive choice among the various CEs studied. [ABSTRACT FROM AUTHOR]

Highlights: [•] In2S3 sensitized solar cells were prepared by a low cost chemical bath deposition (CBD) methodology. [•] Amorphous Y2O3 layer was firstly used as a passivation layer in quantum dot sensitized solar cells. [•] A high FF of 65% was achieved in the solar cell. [ABSTRACT FROM AUTHOR]

Abstract: A novel biosensor for the detection of thrombin was developed by using QDs electrochemiluminescence (ECL) technique. The thiol-terminated aptamer with 15 nucleotides (probe I) was first immobilized on Au electrode, and then thrombin was imported to form the aptamer–thrombin bioaffinity complexes. Another 5′-biotin modified aptamer (29 nucleotides, probe II) was next hybridized with the combined thrombin to form a sandwich type structure. Streptavidin modified QDs (avidin–QDs) were bound to probe II via the biotin–avidin-system. The QDs ECL signal was responsive to the amount of probe II, which was indirect proportional to the combined thrombin. The ECL intensity of the biosensor increased with the increase of thrombin concentration in the range of 0–20μgmL−1. In addition, the biosensor exhibited the excellent selectivity responses and good stability toward the target analyte. [Copyright &y& Elsevier]

In the present work, electrogenerated chemiluminescence (ECL) of luminol was investigated in neutral condition at a gold electrode in the presence of silicon quantum dots (SiQDs). The results revealed that SiQDs can not only greatly enhance luminol ECL, but also act as energy acceptor to construct a novel ECL resonance energy transfer (ECL-RET) system with luminol. As a result, strong anodic ECL signal was obtained in neutral condition at the bare gold electrode, which is suitable for biosensing application. Lysozyme exhibited apparent inhibiting effect on the ECL-RET system, based on which an ECL aptasensor was fabricated for the sensitive detection of lysozyme. The proposed method showed high sensitivity, good selectivity, and wide linearity for the detection of lysozyme in the range of 5.0×10 –14 −5.0×10 −9 g mL −1 with a detection limit of 5.8×10 –15 g mL −1 (3σ). The results suggested that as-proposed luminol/SiQDs ECL biosensor will be promising in the detection enzyme. [ABSTRACT FROM AUTHOR]

An ultrasensitive electrochemiluminescence (ECL) biosensor for the detection of microRNA was developed based on nicking enzymes Nb.BbvCI mediated signal amplification (NESA). First, the hairpin probe1-N-CQDs with assistant probe and microRNA (miRNA) formed Y junction structure which was cleaved with the addition of nicking enzymes Nb.BbvCI to release miRNA and assistant probe. Subsequently, the released miRNA and assistant probe can initiate the next recycling process. The generation of numerous intermediate sequences nitrogen doped carbon quantum dots-DNA (N-CQDs-DNA) can further hybridize with hairpin probe2 immobilized on GO/Au composite modified electrode surface, the initial ECL intensity was enhanced. The ECL intensity would increase with increasing concentration of the target miRNA, and the sensitivity of biosensor would be promoted because of the efficient signal amplification of the target induced cycling reaction. The novel designed biosensor provided a highly sensitive and selective detection of miRNA-21 from 10 aM to10 4 fM with a relatively low detection limit of 10 aM. Thus, our strategy has a potential application in the clinical diagnosis. [ABSTRACT FROM AUTHOR]

A novel, enhanced photoelectrochemical immunoassay was established for sensitive and specific detection of carbohydrate antigen 19-9 (CA19-9, Ag). In this protocol, TiO 2 nanowires (TiO 2 NWs) were first decorated with Au nanoparticles to form TiO 2 NWs/Au hybrid structure, and then coated with CdSe@ZnS quantum dots (QDs) via the layer-by-layer method, producing TiO 2 NWs/Au/CdSe@ZnS sensitized structure, which was employed as the photoelectrochemical matrix to immobilize capture CA19-9 antibodies (Ab 1 ); whereas, bipyridinium (V 2+ ) molecules were labeled on signal CA19-9 antibodies (Ab 2 ) to form Ab 2 @V 2+ conjugates, which were used as signal amplification elements. The TiO 2 NWs/Au/CdSe@ZnS sensitized structure could adequately absorb light energy and dramatically depress electron–hole recombination, resulting in evidently enhanced photocurrent intensity of the immunosensing electrode. While target Ag were detected, the Ab 2 @V 2+ conjugates could significantly decrease the photocurrent detection signal because of strong electron-withdrawing property of V 2+ coupled with evident steric hindrance of Ab 2 . Thanks to synergy effect of TiO 2 NWs/Au/CdSe@ZnS sensitized structure and quenching effect of Ab 2 @V 2+ conjugates, the well-established photoelectrochemical immunoassay exhibited a low detection limit of 0.0039 U/mL with a wide linear range from 0.01 U/mL to 200 U/mL for target Ag detection. This proposed photoelectrochemical protocol also showed good reproducibility, specificity and stability, and might be applied to detect other important biomarkers. [ABSTRACT FROM AUTHOR]

A triple-signal amplification strategy was proposed for highly sensitive and selective detection of thymine DNA glycosylase (TDG) by coupling a dendrimer-like DNA label with the electrochemical method and quantum dots (QDs) tagging. The DNA-QDs dendrimer-like superstructure was designed by DNA hybridization and covalent assembling. Benefiting from outstanding performance of the amplification strategy, this assay showed high sensitivity, extraordinary stability, and easy operation. The limit of detection could reach 0.00003 U µL −1 with a splendid specificity. The TDG content in different concentration of HeLa cell was also determined. This assay opens a new horizon for both qualitative and quantitative detection of TDG, holding great promise for potential application in cancer cell research and clinical diagnostics. [ABSTRACT FROM AUTHOR]

A quasi-solid-state quantum dot-sensitized solar cell (QDSSC) is fabricated by using 12-hydroxystearic acid as a low molecular mass organogelator to gelate the polysulfide electrolyte. Noticeably, the gel to liquid transition temperature of this polysulfide hydrogel electrolyte is 96 °C, which contributes to the long-term stability of the quasi-solid-state QDSSC (QS-QDSSC). The influences of gelation on the charge transport, electron recombination and photovoltaic performance of the QS-QDSSC are investigated by electrochemical impedance spectroscopy. Moreover, the network of the hydrogel is investigated by the Field emission scanning electron microscopy and polarized optical light microscopy. It is found that the charge transport is influenced by the network in the hydrogel electrolyte, and the accelerated electron recombination at the photoanode/electrolyte interface leads to the decreased open-circuit voltage. The QS-QDSSC exhibits an energy conversion efficiency of 2.40% at AM 1.5 (100 mW cm −2 ) which is slightly lower than that of liquid electrolyte based cell (2.88%). However, the QS-QDSSC exhibits significantly improved stability during the accelerated thermal test. Especially, during the accelerated aging test, the short-circuit current density ( J sc ) of the liquid electrolyte based QDSSC sharply decreased to nearly 35% of its initial value, while there is relatively less change in the J sc for the QS-QDSSC. [ABSTRACT FROM AUTHOR]

The anatase TiO 2 nanoparticle films with different thicknesses have been fabricated through screen printing method, and CdS and CdSe quantum dots (QDs) have been deposited on TiO 2 films in turn through successive ionic layer adsorption and reaction (SILAR) method. It has been found that the amount of QDs decreases significantly and the size of QDs increases obviously with the depth increasing in TiO 2 nanoparticle films, and the size distribution of QDs shifts to large-size direction with the TiO 2 film thickness increasing. Furthermore, a qualitative model of CdS/CdSe quantum dot distribution in TiO 2 nanoparticle films has been obtained. After optimizing the TiO 2 film thickness, the quantum dot-sensitized solar cells (QDSCs) with about 10 μm thick nanocrystalline TiO 2 electrodes and Pt counter electrodes have reached relatively high power conversion efficiencies of 3.26 ± 0.10% under one sun illumination (100 mW cm −2 , AM 1.5 G). [ABSTRACT FROM AUTHOR]

Abstract: A sensitive electrochemical aptasensor was successfully fabricated for the detection of adenosine triphosphate (ATP) by combining three-dimensionally ordered macroporous (3DOM) gold film and quantum dots (QDs). The 3DOM gold film was electrochemically fabricated with an inverted opal template, making the active surface area of the electrode up to 9.52 times larger than that of a classical bare flat one. 5′-Thiolated ATP-binding aptamer (ABA) was first assembled onto the 3DOM gold film via sulfur–gold affinity. Then, 5′-biotinated complementary strand (BCS) was immobilized via hybridization reaction to form the DNA/DNA duplex. Since the tertiary structure of the aptamer was stabilized in the presence of target ATP, the duplex can be denatured to liberate BCS. The reaction was monitored by electrochemical stripping analysis of dissolved QDs which were bound to the residual BCS through biotin–streptavidin system. The decrease of peak current was proportional to the amount of ATP. The unique interconnected structure in 3DOM gold film along with the “built-in” preconcentration remarkably improved the sensitivity. ATP detection with high selectivity, wide linear dynamic range of 4 orders of magnitude and high sensitivity down to 0.01nm were achieved. The results demonstrated that the novel strategy was feasible for sensitive ATP assay and provided a promising model for the detection of small molecules. [ABSTRACT FROM AUTHOR]

Abstract: A novel sensing system based on the near infrared (NIR) fluorescence resonance energy transfer (FRET) between Mn:CdTe quantum dots (Qdots) and Au nanorods (AuNRs) was established for the detection of human IgG. The NIR-emitting Qdots linked with goat anti-human IgG (Mn:CdTe-Ab1) and AuNRs linked with rabbit anti-human IgG (AuNRs-Ab2) acted as fluorescence donors and acceptors, respectively. FRET occurred by human IgG with the specific antigen–antibody interaction. And human IgG was detected based on the modulation in FRET efficiency. The calibration graph was linear over the range of 0.05–2.5μM of human IgG under optimal conditions. The proposed sensing system can decrease the interference of biomolecules in NIR region and increase FRET efficiency in optimizing the spectral overlap of AuNRs with Mn:CdTe Qdots. This method has great potential for multiplex assay with different donor–acceptor pairs. [Copyright &y& Elsevier]

Abstract: Electrochemiluminescence (ECL) of CdSe quantum dots (QDs) was greatly enhanced by the combination of carbon nanotubes (CNTs) and poly (diallyldimethylammonium chloride) (PDDA) in the CdSe QDs film, and could successfully be used to develop a sensitive ECL immunosensor for the detection of human IgG (Ag). The novel CdSe QDs–CNTs composites exhibited high ECL intensity, good biocompatibility, and high stability, which held great promise for the fabrication of the ECL biosensors with improved sensitivity. After PDDA as a binding linker was conjugated to the CdSe QDs–CNTs composite film on the electrode, the ECL signal was significantly enhanced. Subsequently, gold nanoparticles (GNPs) assembled onto the CdSe QDs–CNTs/PDDA modified electrode could amplify the ECL signal once again. After antibody (Ab) was immobilized onto the electrode through GNPs, the ECL immunosensor was successfully fabricated. It is for the first time that the unique function of PDDA for enhancing QDs ECL was explored and used to develop an ECL biosensor. The principle of ECL detection for target Ag is based on the increment of steric hindrance after immunoreaction, which resulted in the decrease of ECL intensity. The Ag concentration was determined in the linear range of 0.002–500ngL−1 with a detection limit of 0.6pgmL−1. The sensor showed good fabrication and detection reproducibility, and the assay results were in acceptable agreement with the clinical sera tests, showing a promising clinical application. This work opened the new avenues for applying QDs ECL in highly sensitive bioassays. [Copyright &y& Elsevier]