Hitchhiking Nanoparticles: Mesenchymal Stem Cell-Mediated Delivery of Theranostic Nanoparticles.

Nanotechnology has emerged as a promising solution to permanent elimination of cancer. However, nanoparticles themselves lack specificity to tumors. Due to enhanced migration to tumors, mesenchymal stem cells (MSCs) were suggested as cell-mediated delivery vehicles of nanoparticles. In this study, we have constructed a complex composed of photoluminescent quantum dots (QDs) and a photosensitizer chlorin e6 (Ce6) to obtain multifunctional nanoparticles, combining cancer diagnostic and therapeutic properties. QDs serve as energy donors-excited QDs transfer energy to the attached Ce6 via Förster resonance energy transfer, which in turn generates reactive oxygen species. Here, the physicochemical properties of the QD-Ce6 complex and singlet oxygen generation were measured, and the stability in protein-rich media was evaluated, showing that the complex remains the most stable in protein-free medium. In vitro studies on MSC and cancer cell response to the QD-Ce6 complex revealed the complex-loaded MSCs' potential to transport theranostic nanoparticles and induce cancer cell death. In vivo studies proved the therapeutic efficacy, as the survival of tumor-bearing mice was statistically significantly increased, while tumor progression and metastases were slowed down.

Rodlike Particles of Polydopamine-CdTe Quantum Dots: An Actuator As a Photothermal Agent and Reactive Oxygen Species-Generating Nanoplatform for Cancer Therapy.

Herein, novel rodlike CdTe@MPA-PDA particles based on polydopamine (PDA) loaded with CdTe quantum dots (QDs) capped with mercaptopropionic acid (CdTe@MPA QDs) with atypical chemical features are evaluated as a potential actuator for photothermal therapy and oxidative stress induction. Under mild conditions established for the safe and efficient use of lasers, temperature increases of 10.2 and 7.8 °C, photothermal conversion efficiencies of 37.7 and 26.2%, and specific absorption rates of 99 and 69 W/g were obtained for CdTe@MPA-PDA and traditional PDA particles in water, respectively. The particles were set to interact with the human breast adenocarcinoma cell line MDA-MB-231. A significant cellular uptake with the majority of particles colocalized into the lysosomes was obtained at a concentration of 100 µg/mL after 24 h. Additionally, CdTe@MPA-PDA and CdTe@MPA QDs showed significantly different internalization levels and loading kinetics profiles. For the first time, the thermal lens technique was used to demonstrate the stability of particle-like CdTe@MPA-PDA after heating at pH 7 and their migration within the heating region due to the thermodiffusion effect. However, under acidic pH-type lysosomes, a performance decrease in heating was observed, and the chemical feature of the particles was damaged as well. Besides, the internalized rodlike CdTe@MPA-PDA notably enhanced the induction of oxidative stress compared with PDA alone and CdTe@MPA QDs in MDA-MB-231 cells initiating apoptosis. Combining these effects suggests that after meticulous optimizations of the conditions, the CdTe@MPA-PDA particles could be used as a photothermal agent under mild conditions and short incubation time, allowing cytoplasmatic subcellular localization. On the other hand, the same particles act as cell killers by triggering reactive oxygen species after a longer incubation time and lysosomal subcellular localization due to the pH effect on the chemical morphology features of the CdTe@MPA-PDA particles.

Rolling circle amplification promoted magneto-controlled photoelectrochemical biosensor for organophosphorus pesticides based on dissolution of core-shell MnO2 nanoflower@CdS mediated by butyrylcholinesterase.

A photoelectrochemical (PEC) aptasensing platform is devised for sensitive detection of an organophosphorus pesticide based on dissolution of core-shell MnO2 nanoflower@CdS (MnO2 NF@CdS) by thiocholine (TCh). TCH is produced from the butyrylcholinesterase-acetylthiocholine system, accompanied by target-triggered rolling circle amplification (RCA). The core-shell MnO2 NF@CdS with excellent PEC performance was synthesized and employed as a photo-sensing platform. The target was detected on a functionalized magnetic probe with the corresponding aptamer. Upon malathion introduction, the aptamer was detached from the magnetic beads, while capture DNA (cDNA, with primer fragment) remained on the beads. The primer fragment in cDNA can trigger the RCA reaction to form a long single-stranded DNA (ssDNA). Furthermore, a large number of butyrylcholinesterase (BChE) were assembled on the long ssDNA strands through the hybridization with the S2-Au-BChE probe. Thereafter, TCh generated from hydrolysis of ATCh by BChE can reduce MnO2 NF (core) to Mn2+ and release the CdS nanoparticles (shell) from the platform electrode, significantly enhancing the PEC signal. Under optimal conditions, the proposed aptasensor exhibited high sensitivity for malathion with a low detection limit of 0.68 pg mL-1. Meanwhile, it also presents outstanding specificity, reproducibility, and stability. Importantly, the sensing platform provides a new concept for detection of pesticide. Graphical abstract Herein, this work devised a photoelectrochemical (PEC) aptasensing platform for sensitive detection of organophosphorus pesticide based on dissolution of core-shell MnO2 nanoflower@CdS (MnO2 NF@CdS) by the as-produced thiocholine (TCh) from the butyrylcholinesterase-acetylthiocholine system, accompanying with the target-triggered rolling circle amplification (RCA).

Radiation hardness of cadmium telluride solar cells in proton therapy beam mode.

We evaluated the durability of cadmium telluride (CdTe) solar cells upon proton beam irradiation as well as the possibility of achieving a dosimeter usable in proton beam therapy by applying 100 MeV of pencil beam scanning (PBS) irradiation. Specifically, a 100 MeV proton PBS beam was applied at irradiation doses of 0, 1012, 1013, 1014, and 1015 cm-2. According to the results, the remaining factors (defined as the ratio of the degraded value to the initial value) of open-circuit voltage (Voc), short-circuit current (Jsc), fill-factor (FF), and efficiency (ƞ) which are solar cell performance parameters, were approximately 89%, 44%, 69%, and 30%, respectively, compared to those of the reference cell (without irradiation) at the highest dose of 1×1015 cm-2. In particular, the conversion efficiency, which is the main factor, was approximately 70% of that of the reference cell even at a high fluence of 1×1014 cm-2. In addition, we observed the projected range of the hydrogen atoms based on the PBS beam energy using the Tool for Particle Simulation software and assessed the amount of fluence accumulated in a CdTe cell. As the energy increased, the fluence accumulated inside the cell tended to decrease owing to the characteristics of the Bragg peak of the proton. Thus, the radiation damage to the cell induced by the proton beam was reduced. The results of this study are expected to provide valuable reference information for research on dosimetry sensors composed of thin-film solar cells, serving as the basis for future application in proton beam therapy with CdTe solar cells.

Cu2+-Modulated in situ growth of quantum dots for split-type photoelectrochemical immunoassay of prostate-specific antigen.

A split-type photoelectrochemical immunosensor was designed for the ultrasensitive monitoring of prostate-specific antigen (PSA) based on a Cu2+-mediated catalytic reaction for inhibiting the in situ generation of CdS quantum dots (QDs) coupled with the enhancement of the CdS/MoS2 heterojunction; it was constructed by the stepwise modification of MoS2 QDs and CdS QDs onto an ITO electrode surface. In the presence of PSA, CuO NP-labeled anti-PSA antibodies were immobilized onto an anti-PSA antibody-modified 96-well plate via a sandwich immunoreaction and dissolution by hydrochloric acid to obtain a large number of Cu2+ ions. As the Cu2+-triggered catalytic oxidization of glutathione occurred, the in situ growth of CdS QDs as a signal indicator was significantly suppressed, resulting in reduction in the photocurrent response. Under optimal conditions, the biosensor exhibited desirable linearity in the range from 0.5 pg mL-1 to 10 ng mL-1, low detection limit of 0.29 pg mL-1, satisfactory selectivity, and good stability. It was applied to PSA detection in human serum, suggesting a great potential for early diagnostics of some cancers.

Dual-Channel Photoelectrochemical Ratiometric Aptasensor with up-Converting Nanocrystals Using Spatial-Resolved Technique on Homemade 3D Printed Device.

A near-infrared light-activated ratiometric photoelectrochemical aptasensor was fabricated for detection of carcinoembryonic antigen (CEA) coupling with upconversion nanoparticles (UCNPs)-semiconductor nanocrystals-based spatial-resolved technique on a homemade 3D printing device in which a self-regulating integrated electrode was designed for dual signal readout. The as-prepared NaYF4:Yb,Er UCNPs@CdTe nanocrystals were initially assembled on two adjacent photoelectrodes, then CEA aptamer 1 (A1) and capture DNA (CA) were modified onto two working photoelectrodes (WP1 and WP2) through covalent binding, respectively, and then gold nanoparticle-labeled CEA aptamer 2 (Au NP-A2) was immobilized on the surface of functional WP2 for the formation of double-stranded DNA. Upon target CEA introduction, the various concentrations of CEA were captured on the WP1, whereas the binding of the CEA with Au NP-A2 could be released from the WP2 thanks to the highly affinity of CEA toward A2. The dual signal readout with the "signal-off" of WP1 and "signal-on" of WP2 were employed for the spatial-resolved PEC (SR-PEC) strategy to detect CEA as an analytical model. Combining NaYF4:Yb,Er UCNPs@CdTe nanocrystals with spatial-resolved model on 3D printing device, the PEC ratiometric aptasensor based on steric hindrance effect and exciton-plasmon interactions (EPI) exhibited a linear range from 10.0 pg mL-1 to 5.0 ng mL-1 with a limit of detection of 4.8 pg mL-1 under 980 nm illumination. The SR-PEC ratiometric strategy showed acceptable stability and reproducibility with a superior anti-interference ability. This approach can provide the guidance for the design of ratiometric, multiplexed, and point-of-care biosensors.

Performance of cardiac cadmium-zinc-telluride gamma camera imaging in coronary artery disease: a review from the cardiovascular committee of the European Association of Nuclear Medicine (EANM).

The trade-off between resolution and count sensitivity dominates the performance of standard gamma cameras and dictates the need for relatively high doses of radioactivity of the used radiopharmaceuticals in order to limit image acquisition duration. The introduction of cadmium-zinc-telluride (CZT)-based cameras may overcome some of the limitations against conventional gamma cameras. CZT cameras used for the evaluation of myocardial perfusion have been shown to have a higher count sensitivity compared to conventional single photon emission computed tomography (SPECT) techniques. CZT image quality is further improved by the development of a dedicated three-dimensional iterative reconstruction algorithm, based on maximum likelihood expectation maximization (MLEM), which corrects for the loss in spatial resolution due to line response function of the collimator. All these innovations significantly reduce imaging time and result in a lower patient's radiation exposure compared with standard SPECT. To guide current and possible future users of the CZT technique for myocardial perfusion imaging, the Cardiovascular Committee of the European Association of Nuclear Medicine, starting from the experience of its members, has decided to examine the current literature regarding procedures and clinical data on CZT cameras. The committee hereby aims 1) to identify the main acquisitions protocols; 2) to evaluate the diagnostic and prognostic value of CZT derived myocardial perfusion, and finally 3) to determine the impact of CZT on radiation exposure.

Toxicological impact of cadmium-based quantum dots towards aquatic biota: Effect of natural sunlight exposure.

Cadmium-based quantum dots (QDs) are increasingly applied in existent and emerging technologies, especially in biological applications due to their exceptional photophysical and functionalization properties. However, they are very toxic compounds due to the high reactive and toxic cadmium core. The present study aimed to determine the toxicity of three different QDs (CdS 380, CdS 480 and CdSeS/ZnS) before and after the exposure of suspensions to sunlight, in order to assess the effect of environmentally relevant irradiation levels in their toxicity, which will act after their release to the environment. Therefore, a battery of ecotoxicological tests was performed with organisms that cover different functional and trophic levels, such as Vibrio fischeri, Raphidocelis subcapitata, Chlorella vulgaris and Daphnia magna. The results showed that core-shell type QDs showed lower toxic effects to V. fischeri in comparison to core type QDs before sunlight exposure. However, after sunlight exposure, there was a decrease of CdS 380 and CdS 480 QD toxicity to bacterium. Also, after sunlight exposure, an effective decrease of CdSeS/ZnS and CdS 480 toxicity for D. magna and R. subcapitata, and an evident increase in CdS 380 QD toxicity, at least for D. magna, were observed. The results of this study suggest that sunlight exposure has an effect in the aggregation and precipitation reactions of larger QDs, causing the degradation of functional groups and formation of larger bulks which may be less prone to photo-oxidation due to their diminished surface area. The same aggregation behaviour after sunlight exposure was observed for bare QDs. These results further emphasize that the shell of QDs seems to make them less harmful to aquatic biota, both under standard environmental conditions and after the exposure to a relevant abiotic factor like sunlight.

Left Ventricular Function Assessment Using 2 Different Cadmium-Zinc-Telluride Cameras Compared with a γ-Camera with Cardiofocal Collimators: Dynamic Cardiac Phantom Study and Clinical Validation.

UNLABELLED: This study compared two SPECT cameras with cadmium-zinc-telluride (CZT) detectors to a conventional Anger camera with cardiofocal collimators for the assessment of left ventricular (LV) function in a phantom and patients. METHODS: A gated dynamic cardiac phantom was used. Eighteen acquisitions were processed on each CZT camera and the conventional camera. The total number of counts within a myocardial volume of interest varied from 0.25 kcts to 1.5 Mcts. Ejection fraction was set to 33%, 45%, or 60%. Volume, LV ejection fraction (LVEF), regional wall thickening, and motion (17-segment model) were assessed. One hundred twenty patients with a low pretest likelihood of coronary artery disease and normal findings on stress perfusion SPECT were retrospectively analyzed to provide the reference limits for end-diastolic volume (EDV), end-systolic volume (ESV), ejection fraction, and regional function for each camera model. RESULTS: In the phantom study, for each ejection fraction value, volume was higher for the CZT cameras than for the conventional camera, resulting in a decreased but more accurate LVEF (all P < 0.001). In clinical data, body-surface-indexed EDV and ESV (mL/m(2)) were higher for one of the CZT cameras (Discovery NM 530c) than for the other (D-SPECT) or the conventional camera (respectively, 40.5 ± 9.2, 37 ± 7.9, and 35.8 ± 6.8 for EDV [P < 0.001] and 12.5 ± 5.3, 9.4 ± 4.2, and 8.3 ± 4.4 for ESV [P < 0.001]), resulting in a significantly decreased LVEF: 70.3% ± 9.1% vs. 75.2% ± 8.1% vs. 77.8% ± 9.3%, respectively (P < 0.001). CONCLUSION: The new CZT cameras yielded global LV function results different from those yielded by the conventional camera. LV volume was higher for the Discovery NM 530c than for the D-SPECT or the conventional camera, leading to decreased LVEF in healthy subjects. These differences should be considered in clinical practice and warrant the collection of a specific reference database.

Clinical significance of right ventricular activity on treadmill thallium-201 myocardial single-photon emission computerized tomography using cadmium-zinc-telluride cameras.

OBJECTIVE: Identification of right ventricular (RV) abnormalities is important in patients with suspected coronary artery disease (CAD). RV activity can be better visualized on myocardial single-photon emission computerized tomography (SPECT) using a higher sensitivity cadmium-zinc-telluride (CZT) detector. The aim of this study was to investigate the clinical significance of RV/left ventricular (LV) uptake ratios during exercise thallium-201 SPECT using CZT detectors. PATIENTS AND METHODS: A total of 102 patients underwent treadmill ECG-gated SPECT, coronary angiography, and echocardiography. SPECT myocardial perfusion was interpreted using a 17-segment model and a 0-4-point scale. RV/LV uptake ratios were calculated on the basis of maximum counts per pixel within the entire RV and LV walls. The relationships between RV/LV uptake ratio and gated SPECT, presence of CAD (≥50% stenosis in the left main or ≥70% in the main branches), demographics, and echocardiographic parameters were analyzed. RESULTS: Stress RV/LV ratios correlated positively with the presence of left main or multivessel disease, and tricuspid regurgitation maximum pressure gradient. After multivariate regression, stress/rest RV/LV ratios correlated positively with mitral flow deceleration time, age, female sex, and use of ß-blockers. CONCLUSION: RV/LV uptake ratios on the basis of exercise myocardial perfusion SPECT imaging using CZT cameras are useful for the detection of severe CAD and could serve as an indicator of pulmonary hypertension and LV diastolic dysfunction.

Highly Efficient Photocatalytic Hydrogen Production of Flower-like Cadmium Sulfide Decorated by Histidine.

Morphology-controlled synthesis of CdS can significantly enhance the efficiency of its photocatalytic hydrogen production. In this study, a novel three-dimensional (3D) flower-like CdS is synthesized via a facile template-free hydrothermal process using Cd(NO3)2•4H2O and thiourea as precursors and L-Histidine as a chelating agent. The morphology, crystal phase, and photoelectrochemical performance of the flower-like CdS and pure CdS nanocrystals are carefully investigated via various characterizations. Superior photocatalytic activity relative to that of pure CdS is observed on the flower-like CdS photocatalyst under visible light irradiation, which is nearly 13 times of pure CdS. On the basis of the results from SEM studies and our analysis, a growth mechanism of flower-like CdS is proposed by capturing the shape evolution. The imidazole ring of L-Histidine captures the Cd ions from the solution, and prevents the growth of the CdS nanoparticles. Furthermore, the photocatalytic contrast experiments illustrate that the as-synthesized flower-like CdS with L-Histidine is more stable than CdS without L-Histidine in the hydrogen generation.

Characterization measurement of a thick CdTe detector for BNCT-SPECT - detection efficiency and energy resolution.

Author׳s group is carrying out development of BNCT-SPECT with CdTe device, which monitors the therapy effect of BNCT in real-time. From the design calculations, the dimensions were fixed to 1.5×2×30mm(3). For the collimator it was confirmed that it would have a good spatial resolution and simultaneously the number of counts would be acceptably large. After producing the CdTe crystal, the characterization measurement was carried out. For the detection efficiency an excellent agreement between calculation and measurement was obtained. Also, the detector has a very good energy resolution so that gamma-rays of 478keV and 511keV could be distinguished in the spectrum.

Laser-induced photodynamic effects at silica nanocomposite based on cadmium sulphide quantum dots.

In this paper we study the laser-induced modification of optical properties of nanocomposite based on cadmium sulphide quantum dots encapsulated into thiomalic acid shell which were embedded into a porous silica matrix. We found red shift of luminescence of the nanocomposite when exposed to laser radiation at λ = 405 nm. Using pump-probe method and Small-Angle X-ray Scattering technique it was found that laser radiation at λ = 405 nm also increases the absorption coefficient of the nanocomposite in 15 times due to agglomeration of quantum dots. The modification of absorption properties is fully reversible.

Gated tomographic radionuclide angiography using cadmium-zinc-telluride detector gamma camera; comparison to traditional gamma cameras.

PURPOSE: Estimation of left ventricular ejection fraction (LVEF) with equilibrium 99MTc-HSA equilibrium radionuclide angiography (MUGA) is frequently used for assessing cardiac function. The purpose of this study was to compare intra- and interobserver variation between three different gamma cameras. MATERIALS AND METHODS: Eighty-two patients, scanned in the same sequential order on the three cameras. Each acquisition was analyzed twice by two technologists. Inter- and intraobserver variations were calculated as the coefficient of variation and the 95% confidence interval for limits of agreement between each sequence of analyses for each of the three cameras. RESULTS: The lowest intraobserver variations in LVEF for the two NaI-detector cameras were 3.1% (-4.0% to 3.5%) for the planar and 3.4% (-4.2% to 4.5%) for SPECT (P ≤ 0.001-0.019), the highest result for the CZT SPECT camera was 2.6% (-2.9% to 3.1%). Similarly, interobserver variation was 4.8% (-4.8% to 6.4%) and 4.9% (-5.4% to 7.5%), respectively, for each of the NaI-detector cameras and 3.3% (-3.4% to 4.3%) for the CZT SPECT camera (P ≤ 0.001-0.008). DISCUSSION: The CZT detector camera was superior to both NaI detector cameras regarding intra- and interobserver variation. The CZT SPECT camera may identify changes in LVEF with greater certainty than its NaI detector-equipped counterparts.

In situ photo-assisted deposition of MoS2 electrocatalyst onto zinc cadmium sulphide nanoparticle surfaces to construct an efficient photocatalyst for hydrogen generation.

We reported herein a facile and scalable preparation process for MoS(2)-decorated Zn(x)Cd(1-x)S hybrid photocatalysts for hydrogen generation. Zn(x)Cd(1-x)S nanopowder was first prepared from commercially available precursors employing a solution based process. MoS(2) hydrogen evolution reaction catalyst was then loaded onto the Zn(x)Cd(1-x)S nanopowder via a photo-assisted deposition process which employed mild conditions (room temperature, atmospheric pressure and visible light illumination). Thus, this process represents an important advantage in the large scale production of semiconductor/MoS(2) hybrid photocatalysts in comparison to the conventional method relying on thermal decomposition of (NH(4))(2)[MoS(4)] precursor at high temperature and under H(2)S pressure. The best Zn(0.2)Cd(0.8)S/MoS(2) 3% showed two hundred-and-ten times (210 times) faster hydrogen generation rate on visible light illumination compared with that obtained for un-treated Zn(0.2)Cd(0.8)S. That was the most impressive catalytic enhancement ever recorded for a semiconductor photocatalyst decorated with a noble metal free electrocatalyst.

Sonochemical syntheses of a new nano-plate cadmium(II) coordination polymer as a precursor for the synthesis of cadmium(II) oxide nanoparticles.

Nanoplates of the three-dimensional coordination polymer, {[Cd(3)(3-pyc)(4)(N(3))(2)(H(2)O)](n) (1), 3-pyc(-)=pyridine-3-carboxylate), have been synthesized by a sonochemical process and characterized by scanning electron microscopy, X-ray powder diffraction, IR spectroscopy and elemental analyses. Cadmium(II) oxide nanoparticles were prepared from thermal decomposition in oleic acid and direct calcination of compound 1 at different temperatures. The thermal stability of nano-sized compound 1 was studied by thermal gravimetric (TG) and differential thermal analyses (DTA). Results show that the size and morphology of the CdO nanoparticles are dependent upon the particles size of compound 1 and the thermolysis temperature. A decrease in the particle size of compound 1 leads to a decrease in the particle size of the CdO, while an increase in the processing temperature leads to an increase in the particle size of the produced cadmium(II) oxide nano-particles.

Design and optimization of large area thin-film CdTe detector for radiation therapy imaging applications.

PURPOSE: The authors investigate performance of thin-film cadmium telluride (CdTe) in detecting high-energy (6 MV) x rays. The utilization of this material has become technologically feasible only in recent years due to significant development in large area photovoltaic applications. METHODS: The CdTe film is combined with a metal plate, facilitating conversion of incoming photons into secondary electrons. The system modeling is based on the Monte Carlo simulations performed to determine the optimized CdTe layer thickness in combination with various converter materials. RESULTS: The authors establish a range of optimal parameters producing the highest DQE due to energy absorption, as well as signal and noise spatial spreading. The authors also analyze the influence of the patient scatter on image formation for a set of detector configurations. The results of absorbed energy simulation are used in device operation modeling to predict the detector output signal. Finally, the authors verify modeling results experimentally for the lowest considered device thickness. CONCLUSIONS: The proposed CdTe-based large area thin-film detector has a potential of becoming an efficient low-cost electronic portal imaging device for radiation therapy applications.

A sonochemical method for the preparation of cadmium sulfide and cadmium selenide nanoparticles in aqueous solutions.

Sonochemistry is a branch of chemistry where sound energy in the form of ultrasound is used to influence the course of reactions. A short-term, local increase in temperature occurs when the solutions and suspensions are irradiated by ultrasound. This happens because the substance absorbs the ultrasound waves. The purpose of this research was the synthesis of CdS and CdSe nanoparticles. We used cadmium sulfate hydrate (CdSO(4).8/3H(2)O), elemental S and Se. Aqueous solutions of NaOH, Na(2)SO(3) and EDTA were used as the solvents. During the syntheses, we used a direct immersion ultrasound probe by vibracell. The device operates with a constant frequency of 20 kHz, with the possibility to change the amplitude and with it the input of energy to the time unit. The products were characterized by X-ray powder diffraction (XRD), thermal analyses (TGA, SDTA) and TEM analyses.

Photoactivated CdTe/CdSe quantum dots as a near infrared fluorescent probe for detecting biothiols in biological fluids.

The important roles of biothiols in biological systems have attracted great interest in the determination of biothiols. Although great progress has been made in fluorescent biothiol probes, near-infrared (NIR) fluorescent probes for biothiols are rather few even such NIR probes can avoid interference from biological media such as tissue autofluorescence and scattering light, and thereby facilitate relatively interference-free sensing. Herein, we report photoactivated CdTe/CdSe quantum dots (QDs) as a novel NIR fluorescent probe for biothiols. The photoactivated CdTe/CdSe QDs based NIR fluorescent probe offers good sensitivity and selectivity for detecting cysteine (Cys), homocysteine (Hcy), and glutathione (GSH) in the presence of 20 other amino acids, main relevant metal ions, and some other molecules in biological fluids. The recovery of spiked 5.0 microM thiols in human urine, plasma, and cell extracts ranges from 90% to 109%. The precision for nine replicate measurements of the thiols at 5.0 microM is in the range from 1.6% to 1.8%. The detection limits for Cys, Hcy, and GSH are 131, 26, and 20 nM, respectively. This assay is based on both the superior photoactivity of CdTe/CdSe QDs and the strong affinity of thiols to photoactivated CdTe/CdSe QDs. The addition of thiols into the photoactivated CdTe/CdSe QDs improves the passivation of the illumination-induced traps, meanwhile reduces most of Se(IV) and Te(IV) on the surface of photoactivated CdTe/CdSe QDs so as to improve the fluorescence property.

Support-controlled chemoselective olefin-imine addition photocatalyzed by cadmium sulfide on a zinc sulfide carrier.

The semiconductor catalyzed photoaddition of cyclopentene or cyclohexene to various novel electron-poor imines of type p-XC(6)H(4)(CN)C[double bond, length as m-dash]N(COPh) (X = H, F, Cl, Br, Me, MeO) was investigated as a function of the nature of the cadmium sulfide photocatalyst. Irradiation (lambda>/= 350 nm) of silica supported cadmium sulfide surprisingly did not afford the expected olefin-imine adducts but an imine hydrocyanation product via an unprecedented dark reaction. However, when silica was replaced by zinc sulfide as the support for cadmium sulfide, the expected homoallylic N-benzoyl-alpha-amino cyanides were isolated in yields of 65-84%. Thus, chemoselectivity is introduced through replacing an insulating by a semiconducting support, a hitherto unknown effect in semiconductor photocatalysis. From the sign of the time resolved photovoltage it is found that the mixed metal sulfide interface CdS/ZnS increases the lifetime of photogenerated electron-hole pairs by about one order of magnitude as compared to the SiO(2)/CdS system. The reaction rate increases with increasing imine sigma-Hammett constants and decreasing stability of intermediate benzyl radicals.