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Although black phosphorus analogue, bismuthene, has been extensively investigated in recent years, yet the investigation into the photoelectronic devices is still in its infancy. In this contribution, uniform zero-dimensional (0D) bismuth (Bi) quantum dots (QDs) with different sizes were successfully synthesized by a simple solvothermal method. The as-synthesized 0D Bi QDs serve as working electrode materials by a direct deposition for photoelectrochemical (PEC)-type photodetection. The PEC results demonstrate that the as-fabricated 0D Bi QD-based electrode not only possess suitable self-powered broadband photoresponse, but also displays excellent photodetection performance. Under simulated light, the photocurrent density and photoresponsivity of the as-fabricated 0D Bi QD-based electrode can reach 2690 nA cmâˆ'2, and 22.0 ÎĽ A Wâˆ'1, respectively. In addition, the as-prepared Bi QDs with the average diameter of 17 nm exhibit the best PEC photoresponse behavior in the studied size range of Bi QDs, mainly ascribed to the synergistic effect of suitable band gap and accessible active sites. It is anticipated that the uniform Bi QDs can be served as building blocks for a variety of photoelectronic devices, further expanding the application prospects of bismuthene, and can provide in-depth acknowledge on the performance optimization of monoelement Bi-based optical devices. [ABSTRACT FROM AUTHOR]

Improving photovoltaic efficiency is essential to the early realization of universal solar cell application, which has proven to be the most promising solution to the global energy transition. Therefore, we propose a thin-film GaAs solar cell with TiO 2 quantum dots, plasmonic Ag nanoparticles, and the AlGaAs window layer. First, we using the finite difference time domain method to simulate the electromagnetic wave propagation and the solar cell light absorption under set boundary conditions to test whether the TiO 2 quantum dots and plasmonic Ag nanoparticles can improve the cell light-trapping ability. The results show that the light absorption of the cell can be maintained above 95% in the visible wavelength range of 300–721 nm, with an average absorption of 97.7%. The photoabsorption effect is particularly prominent at 558 nm, with an absorption rate of 99.86%. The p-n junction doping concentration and the molar fraction of the AlGaAs window layer were optimized to obtain better photovoltaic performance parameters. The results show that AlGaAs reduces incident light loss and possesses a higher potential barrier in the emitter region because of its wider band gap, effectively lowering carrier recombination rate and consequently enhancing the photovoltaics characteristics of the cell. The short-circuit current density, open-circuit voltage, and photoelectric conversion efficiency (PCE) of the thin-film GaAs solar cell improved to 30.01 mA/cm2, 1.247 V, and 33.43%, respectively. Thus, this study provides an effective strategy for high-performance fabrication of the thin-film solar cells, demonstrating significant potential for broad applications in cost-effective solar cell usage and mitigating the climate change crisis. • the light absorption of the cell can be maintained above 95% in the visible wavelength range of 300–721 nm, with an average absorption of 97.7%. • The photoabsorption effect is particularly prominent at 558 nm, with an absorption rate of 99.86%. • The short-circuit current density, open-circuit voltage, and photoelectric conversion efficiency (PCE) of the thin-film GaAs solar cell improved to 30.01 mA/cm2, 1.247 V, and 33.43%, respectively. ls. [ABSTRACT FROM AUTHOR]

We present a wavelength shift-based fluorescence detection method for ascorbic acid (AA) using CdTe quantum dots (QDs). Upon addition of ascorbic acid, the fluorescence emission peak of CdTe QDs red shifts linearly with the increase of the AA concentration, and the red shift speed could be improved by increasing the diameter of the QDs. The mechanism has been attributed to the AA-induced size change of the QDs. This AA-dependent red shift of fluorescence emission has been used to detect and quantify AA. Dynamic range and detection limit of this fluorescence probe are found to be 10–250 μmol/L and 1.3 μmol/L, respectively. Interference studies indicate that the AA could be specifically detected by using this wavelength shift-based fluorescence probe, and the QDs with larger diameter have better anti-interference performance. This fluorescence detection method is based on the wavelength shift of the emission peak, which is different from those reported traditional emission intensity-based fluorescent probes. Thus this fluorescence probe has the advantages of higher accuracy and convenient operation, which provides an effective strategy for design of wavelength shift-based fluorescence sensing method. [ABSTRACT FROM AUTHOR]

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]

Cell-derived microparticles (MPs) have been recently recognized as critical intercellular information conveyors. However, further understanding of their biological behavior and potential application has been hampered by the limitations of current labeling techniques. Herein, a universal donor-cell-assisted membrane biotinylation strategy was proposed for labeling MPs by skillfully utilizing the natural membrane phospholipid exchange of their donor cells. This innovative strategy conveniently led to specific, efficient, reproducible, and biocompatible quantum dot (QD) labeling of MPs, thereby reliably conferring valuable traceability on MPs. By further loading with small interference RNA, QD-labeled MPs that had inherent cell-targeting and biomolecule-conveying ability were successfully employed for combined bioimaging and tumor-targeted therapy. This study provides the first reliable and biofriendly strategy for transforming biogenic MPs into functionalized nanovectors. [ABSTRACT FROM AUTHOR]

Cell-derived microparticles (MPs) have been recently recognized as critical intercellular information conveyors. However, further understanding of their biological behavior and potential application has been hampered by the limitations of current labeling techniques. Herein, a universal donor-cell-assisted membrane biotinylation strategy was proposed for labeling MPs by skillfully utilizing the natural membrane phospholipid exchange of their donor cells. This innovative strategy conveniently led to specific, efficient, reproducible, and biocompatible quantum dot (QD) labeling of MPs, thereby reliably conferring valuable traceability on MPs. By further loading with small interference RNA, QD-labeled MPs that had inherent cell-targeting and biomolecule-conveying ability were successfully employed for combined bioimaging and tumor-targeted therapy. This study provides the first reliable and biofriendly strategy for transforming biogenic MPs into functionalized nanovectors. [ABSTRACT FROM AUTHOR]

We present a sensitive and selective method for the determination of organophosphorus pesticides (OPs) based on the inhibition of the enzyme acetylcholinesterase (AChE). It is making use of quantum dots QDs of the type Mn: ZnS that display long-lived phosphorescence emission and act as optical probes for hydrogen peroxide (HO). In this assay, acetylcholine (ACh) is first hydrolyzed by AChE, and the enzyme choline oxidase (ChOx) further oxidizes choline under the formation of HO which quenches the phosphorescence of the QDs. If, however, OPs are added to the solution, the rate of enzymatic hydrolysis by AChE is retarded. This reduces the rate of production of HO and results in a reduced quenching efficiency. The slow decay time of the phosphorescence of the QDs also allows time-resolved luminescence intensity to be measured. This can eliminate background fluorescence from the sample and therefore improves analytical accuracy and the signal-to-noise ratio. Under optimized conditions, there is a linear relationship between luminescence intensity and the concentration of paraoxon in the 1 pM to 1 μM range, with an ~0.1 pM limit of detection which is much lower than that of most existing methods. The phosphorescent probe was applied to determine OPs in spiked real samples. [Figure not available: see fulltext.] [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]

As newly developed inorganic materials, semiconductor nanocrystals (NCs), or quantum dots (QDs), have received considerable attention because of their unique nano-related properties including high quantum yield, simultaneous excitation with multiple fluorescence colors, and electrochemical properties. This review presents a general description of the electrochemical properties of QDs with their electrochemical applications including indirect and direct effects. The fields of inorganic substance analysis, organic analysis, immunoanalysis, DNA analysis and aptamer analysis are discussed in detail. [ABSTRACT FROM AUTHOR]

Quantum dots (QDs) have been facilitating the development of sensitive fluorescence biosensors over the past two decades due to their high quantum yield, narrow and tunable emission spectrum and good photostability. The new emerging QDs with improved biocompatibility further promote their biological applications. In this review, we first briefly introduce the prevalently used QDs and their preparation and bioconjugation approaches. Then we summarize QDs-based fluorescent biosensing for proteins and nucleic acids, and QDs-based applications in cellular and in vivo targeting and imaging. Last but not the least, we envision the potential QDs-based applications in future perspectives. [ABSTRACT FROM AUTHOR]

Abstract: Quantum dot sensitized nanocrystalline TiO2 solar cells (QDSSCs) are promising third-generation photovoltaic devices. A series of CdS/CdSe co-sensitized TiO2 photoanodes for QDSSCs were prepared by successive ionic layer adsorption and reaction (SILAR) processes. The growth of CdS and CdSe layers were monitored by taking UV–Visible absorption spectra and the SILAR cycles of CdS and CdSe show different impact on the performance of QDSSCs. With the deposition times of CdS increasing (from 4 to 7 cycles), the short-circuit current density of the device is enhanced. On the contrary, the increasing deposition times of CdSe (from 4 to 7 cycles) has a negative effect for the generation and collection of photoelectron. In addition, the electrochemical impedance spectroscopy technology was used to investigate the impedance of diffusion and recombination in the various devices. Moreover, the effect of SILAR cycles on the recombination resistance was discussed based on the electrochemical impedance spectroscopy results. [Copyright &y& Elsevier]

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]

Graphical abstract Highlights • Examined the physical properties of CsPbBr 3 perovskite quantum dots by comprehensive characterizations. • Explored its essences of PL of the synthesized CsPbBr 3 perovskite quantum dots. • The CsPbBr 3 quantum dots have a high PLQY and have a promising application in solar cells. Abstract All-inorganic cesium lead halide perovskite nanostructure CsPbBr 3 quantum dots have brought extensive attention in photoelectric applications. In this paper, CsPbBr 3 quantum dots were synthesized with the diameter ranges from 8.7 to 11.8 nm by adjusting reaction temperature from 140 to 180 °C. In addition, for the monodisperse CsPbBr 3 nanocrystals, it was found that radiative lifetime exists between 5 and 20 ns and PL decay lifetimes ranges from 4 to 11 ns, and their PL mechanism was studied thoroughly. [ABSTRACT FROM AUTHOR]

The red-emitting perovskite material has received widespread attention as a long-wavelength optical gain media. But the easy phase change in the air limits its practical application. Herein, red CsPbBr x I3âˆ' x /SiO2 quantum dots (QDs) are prepared by a ligand-mediated hot injection method in which 3-aminopropyl-triethoxysilane (APTES) is used instead of the usual oleylamine (OAm) ligand. Through the hydrolysis of amino groups, a thin silicon layer is formed on the QD surface, improving the stability and without causing the aggregation of QDs. We find that the ratio of I/Br and the size of QDs can be tuned by adjusting the APTES amount. Moreover, this ligand-mediated synthesis effectively passivates the surface defects, so the photoluminescence quantum yield is remarkably improved, and the carrier lifetime is prolonged. The amplified spontaneous emission is achieved under 532 nm nanosecond laser excitation. Compared with the original CsPbBrI2-OAm QD films, the threshold of CsPbBr x I3âˆ' x /SiO2 QD films is reduced from 403.5 to 98.7 ÎĽ J cmâˆ'2, and the radiation stability is significantly enhanced. Therefore, this material shows great potential in the random laser field. [ABSTRACT FROM AUTHOR]

All inorganic cesium lead halide perovskite (CsPbX3; X = Cl, Br, or I) quantum dots (QDs) have received widespread attention as a class of favorable optical gain materials. The key issue of CsPbX3 perovskites is their instability under light or exposure to air. Notably, the inherent phase instability of CsPbI3 QDs severely restricts the development of red-light emission. Herein, we propose a simple method to post-process CsPbBr3 QDs with a ZnI2 solution. The prepared CsPbBryI3−y (named CPBI-z, where z corresponds to the photoluminescence peaks' position) QDs exhibit adjustable photoluminescence in the range of 550–640 nm. The photoluminescence quantum yield is increased from 73.3% to 97.2% as the surface defects of QDs are passivated by I− and Zn2+. Compared with the pristine CsPbBr3 QDs, the post-processed QDs are more stable under ultraviolet irradiation and in the air. Aside from that, under 532 nm nanosecond laser excitation, CPBI-z QD films exhibit excellent amplified spontaneous emission performance. The CPBI-640 QD film shows a low threshold, 102 μJ cm−2 for red stable amplified spontaneous emission. [ABSTRACT FROM AUTHOR]

Achieving high surface coverage of the colloidal quantum dots (QDs) on TiO 2 films has been challenging for quantum dot-sensitized solar cells (QDSCs). Herein, a general surface engineering approach was proposed to increase the loading of these QDs. It was found that S 2 − treatment/QD re-uptake process can significantly improve the attachment of the QDs on TiO 2 films. Surface concentration of the QDs was improved by ∼60%, which in turn greatly enhances light absorption and decreases carrier recombination in QDSCs. Ensuing QDSCs with optimized QD loading exhibit a power conversion efficiency of 3.66%, 83% higher than those fabricated with standard procedures. [ABSTRACT FROM AUTHOR]

CsPbBr3/SiO2 perovskite quantum dots (PQDs), which exhibit good stability in water, air, and light, are synthesised using the water-trigger method. Due to the interaction between the long alkyl ligands of the PQDs and the liquid crystal, the liquid-crystal molecules prefer to align perpendicular to the surface of the PQDs, which disturbs the liquid crystal order and decreases its clearing point. The effect of CsPbBr3/SiO2 PQDs on the electro-optical properties and physical parameters of a nematic liquid crystal are investigated. The dielectric anisotropy (Δε) and splay elastic constant (K11) decrease substantially with increasing concentration of PQDs. PQDs, which are doped into the liquid crystal, can effectively reduce the threshold voltage (Vth), which opens possibilities to reduce energy consumption in many optoelectronic devices. [ABSTRACT FROM AUTHOR]

CdSe/CdS dot‐in‐rod (DiR) nanocrystals are an advantageous heterostructured semiconductor system with a quasi‐type‐II electronic band structure, which enables a rich diversity of optical manipulation of carrier excitations and interactions. Herein, the selective excitation of respective CdSe quantum dots (QDs) and CdS nanorods of the CdSe/CdS DiR nanostructure is reported, which results in the distinct presence of different types of carriers at the nanorod surface. The presence of only electrons at the surface upon CdSe QD excitation leads to photophysical interactions with ambient air, which is manifested as reversible photoluminescence (PL) of the CdSe QDs. The excitation of CdS nanorods produces holes at the surface, which induces photooxidation of the CdS surface and irreversible change in PL intensity and spectral lineshape. Benefitting from unambiguously relating carrier types to photophysical and photochemical interactions, this research also verifies that trap states at the CdS surface do not act as nonradiative recombination centers, which can be removed by photochemical reactions. Herein, distinct roles of electrons and holes in the photophysical and photochemical interactions with ambient air are identified, and a more precise understanding of the interacting mechanisms is achieved. [ABSTRACT FROM AUTHOR]

Abstract A novel enhanced photoelectrochemical (PEC) DNA biosensor, based on a compact heterojunction g-C 3 N 4 /MoS 2 and co-sensitization effect with CdSe quantum dots (QDs), was first proposed for simple and accurate analysis of a short ssDNA. In this work, the g-C 3 N 4 /MoS 2 was successfully synthesized and used as the electrode matrix material to construct PEC biosensor. 2D/2D heterojunction was formed between g-C 3 N 4 and MoS 2 , which could promote the separation of photogenerated electron-hole pairs resulting in an enhanced photocurrent. In the presence of target DNA, CdSe QDs labeled reporter DNA was complementary pairing with target DNA which was specific recognized by capture DNA loading on self-assembled CdS QDs film, leading to close contact between CdSe QDs and g-C 3 N 4 /MoS 2 modified electrode surface, thereby resulting in the enhanced photocurrent intensity due to the co-sensitization effect. Under the optimal operating conditions, the photoelectrochemical biosensor demonstrated favorable accuracy and could respond to 0.32 pM (S/N = 3) with a linear concentration range from 1.0 pM to 2.0 μM. Moreover, the proposed PEC DNA biosensor exhibits high sensitivity, excellent specificity, acceptable reproducibility and accuracy, showing a promising potential in DNA bioanalysis and other relative fields. Graphical abstract A novel enhanced photoelectrochemical DNA biosensor, based on a compact heterojunction g-C 3 N 4 /MoS 2 and co-sensitization effect with CdSe QDs, was proposed for analysis of a short ssDNA. Image 1 Highlights • A novel photoelectrochemical DNA biosensor was constructed for ssDNA detection. • The photocurrent was enhanced by integrating a compact heterojunction g-C 3 N 4 /MoS 2 and co-sensitization effect with CdSe QDs. • The proposed photoelectrochemical protocol presented excellent selectivity. [ABSTRACT FROM AUTHOR]

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]

Halide perovskite materials have emerged as a new class of revolutionary photovoltaic and optoelectronic nanomaterials. However, the study on electrochemiluminescence (ECL) from halide perovskite nanomaterials is still in its infancy due to their instability, sensitivity, and difficulties in purification and film formation. Here, we propose a scraping coating method for the fabrication of high-quality halide perovskite quantum dot (QD) film on electrode, which shows dense and uniform packing with minimum grain size. When CsPbBr3 QDs are taken as model materials, highly efficient ECL can be obtained from such perovskite QD film with anhydrous ethyl acetate as both electrolyte and coreactant. The CsPbBr3 QD film displays intense and stable ECL with ultranarrow emission spectrum bandwidth (24 nm). The CsPbBr3 QD film shows an extremely high ECL efficiency which is up to 5 times relative to the standard Ru(bpy)32+/tri-n-propylamine system. This approach is universal and also applies to hybrid organic-inorganic halide perovskite QDs. This work not only extends the properties and applications of halide perovskite materials but also provides a new method for the in-depth study on the structure and properties of these kinds of materials. [ABSTRACT FROM AUTHOR]

In recent years, amplified spontaneous emission (ASE) properties of all-inorganic perovskite quantum dots have attracted the interest of many researchers. Here, CsPbI 2 Br quantum dots (QDs) were synthesized by the hot injection method, and the effect of the purification process on the ASE properties of QDs has been investigated. In the purification process, n-hexane and ethyl acetate (EtOAc) are used as solvent and antisolvent, respectively. The results show that the volume ratio of n-hexane vs EtOAc has a remarkable effect on the optical performance. When the volume ratio is 1:5, the QDs have a larger size which increases the light scattering and absorption cross-section, thus achieving the lowest ASE threshold of 0.301 mJ/cm2. This work not only provides a facile strategy to obtain a low threshold of CsPbI 2 Br QDs but also enriches the application prospects of perovskite lasers. The amplified spontaneous emission properties of CsPbI 2 Br quantum dots were tuned by the surface ligand density. [Display omitted] • The surface ligand density of CsPbI 2 Br quantum dots is tuned by the ratio of antisolvent vs solvent. • The CsPbI 2 Br quantum dots deliver amplified spontaneous emission. • The effect of surface ligand density on the amplified spontaneous emission properties of CsPbI 2 Br quantum dots is revealed. [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]

Electrogenerated chemiluminescence (ECL) behaviors of luminol were comparatively studied at CdS quantum dos, graphene, and CdS/graphene (CdS/GR) nanocomposites modified gold electrodes in neutral condition. The most intense anodic ECL signal was obtained at the CdS/GR nanocomposites modified gold electrode (CdS/GR/GE). The anodic ECL of luminol (ECL-1) located at ~ 0.50 V (vs SCE) was increased nearly 50-times compared with the bare gold electrode. Besides, two stronger anodic ECL peaks (ECL-2 and ECL-3) were observed at 1.0 V and 1.4 V (vs SCE), respectively. The fluorescence and the UV–vis absorption spectra revealed that resonance energy transfer between luminol and CdS/GR nanocomposites was possible. The ECL spectra further demonstrated the occurrence of ECL resonance energy transfer (ECL-RET), which resulted in strong ECL-2 and ECL-3. Cytochrome C could significantly inhibit the intensities of the anodic ECL peaks, and could be sensitively detected. [ABSTRACT FROM AUTHOR]

Currently, most of CuS counter electrodes (CEs) used in quantum dot-sensitized solar cells (QDSSCs) are provided with a thickness of hundreds of nanometers or even several microns. Considering the CE with low thickness having many advantages, thin CuS films with thickness ranging from 47 nm below to 115 nm have been synthetized in this paper via chemical bath deposition (CBD) method with different bath concentrations. A power conversion efficiency (PCE) of 3.25% has been achieved utilizing CuS thin films a thickness of only 64 nm as CEs in QDSSCs without any structural optimization, which is higher than the value of the cell employing CuS CE with thickness of 2.8 μm. Electrochemical impedance spectroscopy, Tafel polarization, and two-point current-voltage measurements are used to investigate the electrocatalytic and conductive performance of CuS CEs with different thickness. Owing to the highest electrocatalytic capacity and good conductivity of the 64 nm-thick CuS CE, QDSSC assembled with this CE has reached relatively high PCE under one sun illumination (100 mW cm −2 , AM 1.5). In addition, cyclic voltammetry measurements indicate that the thin CuS CE has a good stability against the polysulfide electrolyte. [ABSTRACT FROM AUTHOR]

Electrogenerated chemiluminescence (ECL) of lucignein often suffered from weak signal at positive potential in neutral condition. In the present study, strong anodic ECL was obtained in neutral lucigenin solution at a CdSe quantum dots modified glassy carbon electrode. Electrochemical results suggested that CdSe quantum dots can catalyze the oxidation of lucigenin and bromide, which can generate the anodic ECL. The fluorescence and the ECL spectra revealed that ECL resonance energy transfer (ECL-RET) can occur between lucigenin and CdSe quantum dots. The oxidation product of bromide can promote ECL-RET and increase the anodic ECL signal significantly. The mechanisms of the anodic ECL based on the ECL-RET were proposed. Cytochrome C exhibited apparent inhibiting effect on the anodic ECL emission, based on which a sensitive ECL sensor for the detection of cytochrome C was established. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (g-C3N4) has been commonly used as photocatalyst with promising applications in visible-light photocatalytic water-splitting. Rare studies are reported in applying g-C3N4 in polymer solar cells. Here g-C3N4 is applied in bulk heterojunction (BHJ) polymer solar cells (PSCs) for the first time by doping solution-processable g-C3N4 quantum dots (C3N4 QDs) in the active layer, leading to a dramatic efficiency enhancement. Upon C3N4 QDs doping, power conversion efficiencies (PCEs) of the inverted BHJ-PSC devices based on different active layers including poly(3-hexylthiophene- 2,5-diyl):[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PC61BM), poly(4,8-bis-alkyloxybenzo(l,2-b:4,5-b′)dithiophene-2,6-diylalt-(alkyl thieno(3,4-b)thiophene-2-carboxylate)-2,6-diyl):[6,6]-phenyl C71-butyric acid methyl ester (PBDTTT-C:PC71BM), and poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene-co-3-fluorothieno [3,4-b]thiophene-2-carboxylate] (PTB7-Th):PC71BM reach 4.23%, 6.36%, and 9.18%, which are enhanced by ≈17.5%, 11.6%, and 11.8%, respectively, compared to that of the reference (undoped) devices. The PCE enhancement of the C3N4 QDs doped BHJ-PSC device is found to be primarily attributed to the increase of short-circuit current (Jsc), and this is confirmed by external quantum efficiency (EQE) measurements. The effects of C3N4 QDs on the surface morphology, optical absorption and photoluminescence (PL) properties of the active layer film as well as the charge transport property of the device are investigated, revealing that the efficiency enhancement of the BHJ-PSC devices upon C3N4 QDs doping is due to the conjunct effects including the improved interfacial contact between the active layer and the hole transport layer due to the increase of the roughness of the active layer film, the facilitated photoinduced electron transfer from the conducting polymer donor to fullerene acceptor, the improved conductivity of the active layer, and the improved charge (hole and electron) transport. [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]

In this study, double shelled NIR CdSeTe/CdS/C quantum dots (QDs) were synthesized by a liquid phase method. The as-prepared QDs showed low cytotoxicity and good biocompatibility due to the formation of carbon shell. The imaging of targeted Human cervical carcinoma cells (HeLa cells) indicates that the CdSeTe/CdS/C QDs have excellent optical properties and cell viability. These results clearly shows that the CdSeTe/CdS/C QDs can be a good candidate for bioapplications. [ABSTRACT FROM AUTHOR]

The use of solar energy is a promising means for pollution abatement or environmental remediation. In the present work, we report the design and fabrication of Bi 2 WO 6 QDs/g-C 3 N 4 binary heterojunction photocatalysts with highly efficient solar light response, wherein the Bi 2 WO 6 QDs were in situ uniformly immobilized on porous g-C 3 N 4 ultrathin nanosheets (NSs) by one-pot hydrothermal strategy. The photocatalytic performance of the Bi 2 WO 6 QDs/g-C 3 N 4 NSs hybrid composites was evaluated for the photodegradation of Rhodamine B (RhB). It was found that the mass ratio of Bi 2 WO 6 QDs to g-C 3 N 4 nanosheets in the composites significantly affects the photocatalytic activity. Higher amounts of g-C 3 N 4 nanosheets in Bi 2 WO 6 QDs/g-C 3 N 4 composites showed lower photocatalytic activity. The composite with 10 mg g-C 3 N 4 nanosheets exhibited the highest photocatalytic activity, with nearly 11-fold enhancement in photocatalytic efficiency over pure Bi 2 WO 6 QDs. Different from previous reports, a novel Z-scheme photocatalytic mechanism was proposed to explain the enhanced the photocatalytic efficiency. [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]

High-efficient exciton energy transfer between CdSeTe alloyed quantum dots and SiO2@Au nanocomposites was applied to develop an enhanced photoelectrochemical aptasensing platform with ultrahigh sensitivity, good selectivity, reproducibility and stability. [ABSTRACT FROM AUTHOR]

Vacuum thermal evaporated Cu x S (VTE-Cu x S) film on fluorine-doped tin oxide substrate has been investigated as counter electrode (CE) for quantum dot-sensitized solar cells (QDSCs) with polysulfide electrolyte. The photovoltaic parameters of QDSCs show an obvious dependence on the annealing time of Cu x S film, and the maximum power conversion efficiency of 3.16 ± 0.05% under one sun illumination (100 mW cm −2 , AM 1.5 G) was obtained when the VTE-Cu x S CE was annealed at 270 °C for 300 s (VTE-Cu x S-300s CE). Electrochemical impedance spectroscopy, Tafel polarization, and cyclic voltammetry measurements have been employed to investigate the electrocatalytic activity of VTE-Cu x S-300s CE. The electrocatalytic activity of the VTE-Cu x S-300s CE is much higher than that of Pt CE, and is slightly higher than that of Cu 2 S CE in situ prepared on brass sheet. In particular, VTE-Cu x S-300s CE holds high diffusion velocity of S 2− /S n 2− in polysulfide electrolyte, and the stability of its electrocatalytic activity in polysulfide electrolyte is better than that of Pt and Brass-Cu 2 S CEs obviously. [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]

Quantum dots (QDs), with confined size on the nanoscale (1–10 nm), are usually made of II−VI B group or III−V A group elements or their alloyed semiconductor materials. QDs are endowed with prominent electrochemical and photophysical properties, which makes QD-based assays powerful probes for electrochemical bioanalysis. Both excellent signal enhancement and functionalization have been explored and further developed. In this review, we start by briefly introducing the electrochemical and photophysical characteristics of QDs. Next, the mechanism of QDs for electrochemical cell analysis is systematically stated and critically reviewed from the three aspects of the main components, mechanism, and principle of QD-based electrochemistry (EC), electrochemiluminescence (ECL) and photoelectrochemistry (PEC) cytosensing, individually. The main context will focus on the critical comparison of advantages and disadvantages, similarities, and differences among EC, ECL and PEC. In addition, we summarize selected articles from 2017 to 2021 on QD-based electrochemical cytosensors and discuss the different detection abilities of specific targets, including quantitative cell detection, cell surface biomarkers, cell metabolism, and single-cell analysis. • Surface chemistry and electrochemistry of QDs have been discussed. • Main components, mechanism, and principle of QDs-based electrochemical cytosensing have been critically discussed. • Special emphasis has been focused on the fundamentals and concise comparison among EC, ECL and PEC. • Cell quantitative detection, cell surface biomarkers, cell metabolism, and even single cells analysis have been reviewed. [ABSTRACT FROM AUTHOR]

Highlights: [•] Pulsed sonoelectrochemical technique was employed to synthesize water-soluble CdTe quantum dots. [•] Need no precursor preparation and N2 protection. [•] The size and luminescence of QDs can be easily adjusted for use as promising building blocks. [Copyright &y& Elsevier]

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. [ABSTRACT FROM AUTHOR]

Abstract: The Cu2ZnSnS4 (CZTS) thin films with uniform and porous surface feature with the pore size of 100-200nm were successfully prepared by pyrolysis procedure using the methanol solution containing copper chloride dihydrate (0.06mol dm−3), zinc chloride (0.03mol dm−3), stannous chloride dihydrate (0.03mol dm−3), thiourea (0.48mol dm−3) and deionized water (1.92mol dm−3) as precursor solution at 380°C in air atmosphere. Electrochemical impedance spectroscopy was applied to evaluate the electrochemical catalytic activity of the pyrolysis CZTS thin films for redox couple of Sn 2-/S2− and the charge transfer resistance was 64.08Ω using the pyrolysis CZTS thin film obtained by repeating the procedure of dipping the FTO substrate into the precursor solution and heating at 380°C for 7 cycles. The assembled quantum dot-sensitized solar cells gave an open-circuit photovoltage of 0.52V, a short-circuit photocurrent density of 12.96mAcm−2, and a fill factor of 0.38, corresponding to the photoelectric conversion efficiency of 2.56%. Because the pyrolysis procedure was a facile, low cost and vacuum-free process, and had the advantage of obtaining various porous microstructure thin films and allowing deposition over large areas, the pyrolysis CZTS thin films can serve as an effective counter electrode for QDSCs. [Copyright &y& Elsevier]

Abstract: A specially tailored electrochemical biosensor for ultrasensitive detection of BCR/ABL fusion gene was developed with high selectivity, acceptable rapidity and excellent extensibility. Taking advantage of circular strand replacement polymerization, cascade hybridization reaction as well as quantum dot based signal amplification, the proposed biosensor showed high sensitivity with the detection limit down to 2fM. This strategy offers a great promise to early diagnosis and prognosis of chronic myeloid leukemia. [Copyright &y& Elsevier]

Abstract: We investigated the optical bistability of a quantum dot molecule under coherent excitation and considering the spontaneous exciton decay and pure dephasing as two decoherence channels. Because of the efficient destructive quantum interference established by the tunneling coupling, it is found that the appearance and disappearance of OB can easily be controlled by adjusting the position of the tunneling induced transparency window. Our scheme opens the possibility to control OB with electric gates. [Copyright &y& Elsevier]

Abstract: MicroRNA-16 (miR-16) frequently deleted or downregulated in patients with B cell chronic lymphocytic leukemia and thus can be used as promising biomarkers in B-CLL diagnosis and prognosis. Herein, an ultrasensitive miR-16 detection was carried out by combining rolling circle amplification (RCA), quantum dots tagging and anodic stripping voltammetric detection (ASV). The method could specifically quantify miR-16 over a 6-decade dynamic range and reach an ultra-low detection limit of 0.32 aM. [Copyright &y& Elsevier]

A dual signal amplification strategy was designed for electrochemical detection of matrix metalloproteinase-9 with the integration of electrically heated carbon electrode technique and quantum dots labels. [ABSTRACT FROM AUTHOR]

Hsp70 proteins are implicated in resistance to chemotherapy in cancers, the detection of which is important for cancer treatment and prognosis. In this work, we report the study on the detection of specific intracellular target protein in fixed cells using GlcNAc-conjugated CdSeTe QDs. The QDs were coupled with Con A via a carbodiimide reaction and then were further assembled with GlcNAc by lectin–carbohydrate interaction between Con A and GlcNAc. The obtained QDs-Con A-GlcNAc conjugates have an emission wavelength at 650 nm that is close to the near-infrared (NIR) regions and a specific recognition for Hsp70. These results show that the QDs-Con A-GlcNAc probe can be a promising tool for direct localization of the Hsp70 protein. [ABSTRACT FROM AUTHOR]

Abstract: A novel competitive electrochemical cytosensor was reported by using aptamer (Apt)-quantum dots (Qdots) conjugates as a platform for tumor cell recognition and detection. The complementary DNA (cDNA), aptamer and Qdots could be assembled to the gold electrode surface. When the target cells existed, they could compete with cDNA to bind with Apt-Qdots conjugates based on the specific recognition of aptamer to MUC1 protein overexpressed on the cell surface, which resulted in the denaturation of double-stranded DNA structure and the release of the Apt-Qdots conjugates from the electrode. Electrochemical stripping measurement was then employed to determine the Cd2+ concentration in Qdots left at the electrode. The peak current was inversely proportional to the logarithmic value of cell concentration ranging from 1.0×102 to 1.0×106 cellsmL−1 with a detection limit of 100cellsmL−1. Meanwhile, the recognition of aptamer to the target cells could be clearly observed through the strong fluorescence from Qdots. This is an example of the combination of aptamer and nanoparticles for the application of cell analysis, which is essential to cancer diagnosis and therapy. [Copyright &y& Elsevier]

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: The near-infrared (NIR)-emitting CdSeTe alloyed quantum dots (AQdots) that capped with l-cysteine were applied for ultrasensitive Cu2+ sensing. The sensing approach was based on the fluorescence of the AQdots selectively quenched in the presence of Cu2+. 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 Cu2+ ranging from 2×10−8 to 2×10−6 molL−1. Furthermore, it has been successfully applied to the detection of Cu2+ in vegetable samples. [Copyright &y& Elsevier]

An electrochemical-TUNEL method was developed for a cell sensor. A 3-D bio-interface based on CNT@PDA–FA was employed in the cytosensor, which significantly improved the cell capture. By coupling with a QD-based nanoprobe and electrochemical stripping analysis, the cytosensor exhibited attractive performance for detection of apoptotic cells. [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]