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Doping quantum dots (QDs) with extra element presents a promising future for their applications in the fields of environmental monitoring, commercial products and biomedical sciences. However, it remains unknown for the influence of doping on the molecular biocompatibility of QDs and the underlying mechanisms of the interaction between doped-QDs and protein molecules. Using the "one-pot" method, we synthesized N-acetyl-l-cysteine capped CdTe: Zn 2+ QDs with higher fluorescence quantum yield, improved stability and better molecular biocompatibility compared with undoped CdTe QDs. Using digestive enzyme trypsin (TRY) as the protein model, the interactions of undoped QDs and Zn-doped QDs with TRY as well as the underlying mechanisms were investigated using multi-spectroscopy, isothermal titration calorimetry and dialysis techniques. Van der Waals forces and hydrogen bonds are the major driving forces in the interaction of both QDs with TRY, which leading to the loosening of protein skeleton and tertiary structural changes. Compared with undoped QDs, Zn-doped QDs bind less amount of TRY with a higher affinity and then release higher amount of Cd. Zn-doped QDs have a less stimulating impact on TRY activity by decreasing TRY binding and reducing Cd binding to TRY. Taken all together, Zn-doped QDs offer a safer alternative for the applications of QDs by reducing unwanted interactions with proteins and improving biocompatibility at the molecular level., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The bioaccumulation potential and toxic effects of engineered nanomaterials (ENMs) to earthworms are poorly understood. Two studies were conducted following OECD TG 222 on Eisenia fetida to assess the effects of CdTe QDs with different coatings and soil ageing respectively. Earthworms were exposed to carboxylate (COOH), ammonium (NH 4 + ), or polyethylene glycol (PEG) coated CdTe QDs, or a micron scale (bulk) CdTe material, at nominal concentrations of 50, 500 and 2000 mg CdTe QD kg -1 dry weight (dw) for 28 days in Lufa 2.2 soil. In the fresh soil study, earthworms accumulated similar amounts of Cd and Te in the CdTe-bulk exposures, while the accumulation of Cd was higher than Te during the exposures to CdTe QDs. However, neither the total Cd, nor Te concentrations in the earthworms, were easily explained by the extractable metal fractions in the soil or particle dissolution. There were no effects on survival, but some retardation of growth was observed at the higher doses. Inhibition of Na + / K + -ATPase activity with disturbances to tissue electrolytes, as well as tissue Cu and Mn were observed, but without depletion of total glutathione in the fresh soil experiment. Additionally, juvenile production was the most sensitive endpoint, with estimated nominal EC 50 of values >2000, 108, 65, 96 mg CdTe kg -1 for bulk, PEG-, COOH- and NH 4 + -coated CdTe QDs, respectively. In the aged soil study, the accumulation of Cd and Te was higher than in the fresh soil study in all CdTe QD exposures. Survival of the adult worms was reduced in the top CdTe-COOH and -NH 4 + QD exposures by 55 ± 5 and 60 ± 25%, respectively; and with decreases in growth. The nominal EC 50 values for juvenile production in the aged soil were 165, 88, 78 and 63 mg CdTe kg -1 for bulk, PEG-, COOH- and NH 4 + -coated CdTe QDs, respectively. In conclusion, exposure to nanoscale CdTe QDs, regardless of coating, caused more severe toxic effects that the CdTe bulk material and the toxicity increased after soil ageing. There were some coating-mediated effects, likely due to differences in the metal content and behaviour of the materials., Competing Interests: Declaration of competing interest The authors alone are responsible for the content and writing of the paper. The authors report no conflicts of interest., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

RNA as a carrier of genetic information plays a critical role in various physiological processes. RNA-rich nucleolus is usually employed as an important biomarker for many malignant diseases. Herein, RNA-responsive fluorescent carbon dots (CDs) were synthesized by a simple microwave method. Due to the presence of cationic benzothiazolium groups in the CDs, a "turn-on" fluorescence signal was achieved between CDs and RNA. The CDs exhibit excellent RNA selectivity and a good linear relationship with a detection limit of 0.62 μg/mL. The small particle size, polarity sensitivity and RNA response behavior of CDs realized fast and wash-free nucleolus imaging effectively. Overall, these CDs provide a powerful potential tool for monitoring cell nucleus activity and elucidating RNA dynamics., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Nitrogen and sulfur co-doped carbon dots (N,S-CDs) have been widely studied with high quantum yield (QY). The experimental conditions of three different N,S-CDs were optimized. Emission peak position of three different N,S-CDs shown almost remains unchanged or obvious excitation-dependent PL properties, that was likely owed to size distribution. In order to discuss the N,S-CDs stability of photoluminescence property in environment, various experiments such as the photostability, different pH, ionic strengths and temperature were designed. To sum up, three different N,S-CDs exhibited discrepancy property. Molecular interaction of three different N,S-CDs were produced via vary carbon source with human serum albumins have been investigate by various methods. The quenching mechanism, thermodynamic and kinetic parameters, binding sites, electrochemical behavior of three different N,S-CDs with human serum albumins have some different, but conformational change of three different N,S-CDs with human serum albumins alike. The molecular docking had successful applied to study the N,S-CDs interaction with HSA. Different N,S-CDs possessed various characteristic that will have different quenching mechanism when they interaction with human serum albumin, study the mechanism of action at molecular level will help people to choose suitable CDs to apply in nanomedical., Competing Interests: Declaration of competing interest There are no conflicts to declare., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Telomerase activity is inhibited in normal somatic cells but abnormally high in the majority of cancer cells. Maintenance of active telomerase in cancer cells promotes proliferation and immortalization. With the difference in telomerase activity between cancer and normal cells in mind, we designed a nanoprobe based on quantum dot (QD) and fluorescence resonance energy transfer (FRET). The nanoprobe consisted of a specific sequence of DNA with the two ends labeled with QD as a fluorescent donor and Alexa488 as a fluorescent acceptor, respectively. FRET signal tracking was performed by adjusting the distance between donors and acceptors, and changes in the FRET signal shown to be related to telomerase activity. Incubation of cells with the nanoprobe facilitated sensing of intracellular telomerase activity, and consequent discrimination between normal and cancer cells. Our novel DNA nanoprobe based on QD-FRET achieved sensitive detection of telomerase in cells up to a detection limit of one cell, and quantitative detection of telomerase activity in different numbers of cells. The nanoprobe generated in this study is expected to allow dynamically monitoring of the changes in telomerase activity in cells under treatment with drugs, providing a potential basis for early diagnosis and management of cancer., (Copyright © 2019 Elsevier B.V. All rights reserved.)

A retrograde transportation nerve probe, Au nanodots-cholera toxin B subunit (AuNDs-CTB), are prepared and fully characterized, which emit bright red fluorescence and show high quantum yield (7.2%) and good stability. The fluorescence emitted by the AuNDs is constant across a wide pH range (4-10) and after prolonged UV irradiation (>4 h). Previously, CTB has shown targeting characteristic for nerve cells with high sensitivity and effectiveness. After linking CTB to AuNDs through amidation reactions, AuNDs-CTB are obtained with excellent fluorescence property, nerve target characteristic, and, particularly, neural retrograde transportation feature. The red emission of the AuNDs-CTB is well distinguished from the blue autofluorescence of normal tissues, which provides potential for detection by naked eyes. Further, the fluorescence emission intensity maintains for 10 days in vivo, suggesting great utility for long-time monitoring and sensing of the nerve tissue. Furthermore, the AuNDs-CTB with bright red fluorescence can travel through the peripheral nerve to the spinal cord rapidly by retrograde transportation. The transportation occurs for a long distance (>5 cm) within only 2 days after injection of the AuNDs-CTB into the sciatic nerve. The present study exhibits a novel method for nerve visualization and drug delivery. STATEMENT OF SIGNIFICANCE: Au nanodots (AuNDs) conjugated with cholera toxin subunit B (CTB) have been developed for nerve labeling and neural retro-transporting. The red fluorescence from AuNDs-CTB is stable in vitro (pH 4-10 and 4 h UV irradiation) and in vivo (for a long time, more than 10 days). When injecting AuNDs-CTB into the sciatic nerve located at the midpiece of the thigh, the targeted nerve emits bright red fluorescence under UV light. Furthermore, the nerve can retrograde transport the AuNDs-CTB to the spinal cord for a distance of more than 5 cm just in 2 days. This work exhibits a novel method for nerve visualization by naked eyes and demonstrates the potential for intraoperative navigation., (Copyright © 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

Knowledge of the intracellular behavior of quantum dots (QDs), which encompasses the antiproliferative effect on living cells, is still limited. For this reason, the transformations of CdSeS/ZnS-based QDs in cancer cytosol were examined using capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC) hyphenated with inductively coupled plasma MS (ICP-MS). CE-ICP-MS method revealed the dose- and time-dependent speciation changes of QDs in the cytosol, while HPLC-ICP-MS (in the size-exclusion chromatography mode) allowed further characterization of the resulting Cd species. In such an appraisal, the decent CE advantage of high resolution is well complemented by higher sensitivity of HPLC (LOD 4.0 × 10 -10 and 5.4 × 10 -12  mol/L Cd, respectively). Additionally, the influence of serum protein corona on the surface of QDs on their uptake by Hep G2 cancer cells was investigated by direct ICP-MS analysis that revealed that the conjugated proteins greatly reduce the particle internalization., (Copyright © 2019 Elsevier Inc. All rights reserved.)

The present study focused on the bioaccumulation and cytotoxicities of Cd 2+ , CdSe quantum dots (QDs) and CdSe/ZnS QDs in Escherichia coli (E. coli, represents prokaryotic system) and Phanerochaete chrysosporium (P. chrysosporium, represents eukaryotic system), respectively. Two types of QDs were characterized by transmission electron microscopy (TEM) and dynamic light scattering. The inductively coupled plasma optical emission spectrometer results showed that the bioaccumulation amounts of CdSe QDs by E. coli and P. chrysosporium were larger than those of CdSe/ZnS QDs due to the smaller particle size and less negative surface charges of CdSe QDs. Confocal microscopy and TEM results showed that there was an interaction between QDs and cells, and QDs have entered into the cells eventually, leading to the change of cell morphology. Plasma membrane fluidities and membrane H + -ATPase activities of E. coli and P. chrysosporium decreased gradually with the increasing concentrations of Cd 2+ , CdSe and CdSe/ZnS QDs. Results of the cell viabilities and intracellular reactive oxygen species levels indicated that the induced cytotoxicities were decreased as follows: CdSe QDs > CdSe/ZnS QDs > Cd 2+ . These findings suggested that the cytotoxicity of QDs was not only attributed to their heavy metal components, but also related to their nanosize effects which could induce particle-specific toxicity. The above results offer valuable information for exploring the cytotoxicity mechanism of QDs in prokaryote and eukaryote., (Copyright © 2019 Elsevier Inc. All rights reserved.)

During carcinogenesis, changes in the glycosylation can modulate many biological processes. Thus, the interest in exploring and understanding the roles of carbohydrates as cancer biomarkers has been increasing. Lectins have been applied as useful tools in glycobiology, especially when associated with fluorescent reporters. Therefore, to take advantage of the physicochemical properties of quantum dots (QDs), herein, we conjugated Cramoll, a lectin that recognizes glucose/mannose residues, with those nanoparticles. We applied the conjugates to investigate the glycocode of normal, fibroadenoma (FB), and invasive ductal carcinoma (IDC) human breast tissues. Additionally, we proposed a method to quantitatively evaluate the tissue labeling intensity by a fluorescence microplate assay (FMA). Conjugates showed intense fluorescence and specificity. The lectin activity and secondary structure were also preserved after the conjugation with QDs. Moreover, fluorescence images showed that ductal cells of normal and FB tissues were preferentially labeled by conjugates, whereas both cells and stroma were strongly labeled in IDC. FMA showed in a quantitative, practical, and sensitive way that the level of exposed glucose/mannose residues increased accordingly to the sample malignancy degree. In conclusion, QDs-Cramoll conjugates can be considered effective, specific, and versatile probes to evaluate glycan profiles in normal and transformed tissues, by fluorescence microscopy as well as FMA quantification. Furthermore, FMA showed to be a potential method that can be applied with other fluorescent conjugates., (Copyright © 2019 Elsevier B.V. All rights reserved.)

This study describes synthesis of N‑acetyl‑l‑cysteine-capped CdTe quantum dots (QDs) and investigates their interaction with plasma protein fibrinogen (FIB) and the structural changes of FIB. It is shown that the interaction of QDs with FIB is a spontaneous process and the major driving forces are van der Waals forces and hydrogen bonds. Multi-spectroscopic measurements show that the intrinsic fluorescence of FIB was quenched and secondary and tertiary structures were altered due to the interaction with QDs. In addition, the aggregation state of FIB was altered in the presence of QDs. Furthermore, the formed complexes of FIB with QDs reduced the cytotoxicity of QDs. The coating of FIB on QDs could lower intracellular QDs uptake and therefore result in less released cadmium ions and ROS productions. This study, therefore, might be helpful to the comprehensive understanding of QDs toxicity and provide evidence for assessing the safe application of nanoparticles., (Copyright © 2019. Published by Elsevier B.V.)

Carbon dots (C-dots) were used to study the binding mechanisms with serum protein, bovine serum albumin (BSA) by using two notable binding systems known as non-covalent and covalent interaction. Interaction between C-dots and BSA were estimated by Stern-Volmer equation and Double Log Regression Model (DLRM). According to the fluorescent intensity, quenching of model carrier protein by C-dots was due to dynamic quenching for non-covalent and static quenching for covalent binding. The binding site constant, K A and number of binding site, for covalent interaction is 1754.7L/mol and n≈1 (0.6922) were determined by DLRM on fluorescence quenching results. The blue shift of the fluorescence spectrum, from 450nm to 421nm (non-covalent) and 430nm (covalent) and suggested that both the microenvironment of C-dots and protein changed in relation to the protein concentration. The fluorescence intensity results show that protein structure has a significant role in Protein-C-dots interactions and type of binding influence physicochemical properties of C-dots differently. Understanding to this bio interface is important to utilize both quantum dots and biomolecules for biomedical field. It can be a useful guideline to design further applications in biomedical and bioimaging., (Copyright © 2018. Published by Elsevier B.V.)

Pseudomonas stutzeri TS44 was able to aerobically reduce Se(IV) into SeNPs and transform Se(IV)/Cd(II) mixture into CdSe-QDs. The SeNPs and CdSe-QDs were systematically characterized by surface feature analyses, and the molecular mechanisms of SeNPs and CdSe-QD formation in P. stutzeri TS44 were characterized in detail. In vivo, under 2.5 mmol/L Se(IV) exposure, GorA was essential for catalyzing of Se(IV) reduction rate decreased by 67% when the glutathione reductase gene gorA was disrupted, but it was not decreased in the glutathione synthesis rate-limiting gene gshA mutated strain compared to the wild type. The complemented strains restored the phenotypes. While under low amount of Se(IV) (0.5 mmol/L), GSH played an important role for Se(IV) reduction. In vitro, GorA catalyzed Se(IV) reduction with NADPH as the electron donor (Vmax of 3.947 ± 0.1061 μmol/min/mg protein under pH 7.0 and 28℃). In addition, CdSe-QDs were successfully synthesized by a one-step method in which Se(IV) and Cd(II) were added to bacterial culture simultaneously. GSH rather than GorA is necessary for CdSe-QD formation in vivo and in vitro. In conclusion, the results provide new findings showing that GorA functions as a selenite reductase under high amount Se(IV) and GSH is essential for bacterial CdSe-QD synthesis., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The bioaccumulation, cell, tissue distribution, and biological effects of 5 nm glutathione-capped CdS quantum dots (CdS QDs) in mussels was compared to bulk and aqueous Cd forms through a two-tier experimental approach. In the 1st tier, mussels were exposed for 3 d to 0.05, 0.5 and 5 mg Cd/l (QDs, bulk, aqueous), bioaccumulation, distribution and lysosomal responses were investigated. In the 2nd tier, mussels were exposed for 21 d to the same forms at the lowest effective concentration selected after Tier 1 (0.05 mg Cd/l), biomarkers and toxicopathic effects were investigated. Accumulation was comparable in QDs and aqueous Cd exposed mussels after 3 d. After 21 d, QDs exposed mussels accumulated less than mussels exposed to aqueous Cd and localised in the endo-lysosomal system and released to the alveoli lumen (21 d) after exposure to QDs and aqueous Cd. Intracellular levels of Cd increased on exposure to QDs and aqueous Cd, and to a lesser extent to bulk, and accompanied by the up-regulation of metallothionein 10 (1 d) and 20 (1, 21 d). Lysosomal membrane destabilisation depended on Cd 2+ released by all forms but was marked after exposure to aqueous Cd (1 d). Toxicopathic effects (vacuolisation, loss of digestive cells and haemocytic infiltration) were evident after exposure to QDs (1 d) and aqueous Cd (21 d). Toxicity most likely depended on the ionic load resulting from Cd 2+ release from the different forms of Cd; yet nanoparticle-specific effects of QDs cannot be disregarded., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Mercury ions (Hg 2+ ) are one of the compulsory items in the quality control of herbal medicines for its serious toxicity to human health. Highly selective and sensitive Hg 2+ detection, especially in complex real samples, is still challenging. In this work, Fluorescent (FL) carbon dots (CDs) with a core-shell structures composed of the crystalline core of stacked sp2-hybridized carbon layers and the shell of functional groups on the periphery of carbon layers are facilely prepared through a one-step hydrothermal synthetic route. They can specifically interact with Hg 2+ in aqueous medium to form aggregates, during which coordination of carboxyl functional groups on the surface of CDs with Hg 2+ occurred, which facilitated electron transfer from the CDs to Hg 2+ . As a result, fluorescence of the CDs was quenched with a high efficiency, making the detection of Hg 2+ highly sensitive with the limit of determination (LOD) of 2.2 nM (3σ). With that, detection of Hg 2+ in the complex compound herbal medicines samples with highly reproducible results has been successfully realized by using the as-prepared CDs, showing that fluorescent CDs-based probe may have great potential in the quality controls of heavy metals for pharmaceutical analysis., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Quantum dot (QD) nanoparticles are highly promising contrast agents and probes for biomedical applications owing to their excellent photophysical properties. However, toxicity concerns about commonly used cadmium-based QDs hinder their translation to clinical applications. In this study we describe the in vivo biodistribution and toxicology of indium-based water soluble QDs in rats following intravenous administration. The biodistribution measured at up to 90 days showed that QDs mainly accumulated in the liver and spleen, with similar elimination kinetics to subcutaneous administration. Evidence for QD degradation in the liver was found by comparing photoluminescence measurements versus elemental analysis. No organ damage or histopathological lesions were observed for the QDs treated rats after 24 h, 1 and 4 weeks following intravenous administration at 12.5 mg/kg or 50 mg/kg. Analysis of serum biochemistry and complete blood counts found no toxicity. This work supports the strong potential of indium-based QDs for translation into the clinic., (Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.)

Early diagnosis of chronic, critical diseases improves clinical outcomes, and biomarkers play an important role as an indicator of severity or presence of a disease. Alkaline phosphatase (ALP) is one such vital biomarker in the diagnosis of several diseases. Herein we introduce a facile, sensitive fluorescent assay, based on the inner filter effect (IFE), for ALP activity determination in serum and in living cells. It is well known that the key to maximize the sensitivity of an IFE-based fluorescence assays is to broaden the overlap between the absorption of an absorber and the excitation/emission of a fluorophore. We employed CuInS/ZnS quantum dots (CIS/ZnS QDs) and p-nitrophenylphosphate (PNPP) as the fluorescent indicator and the substrate, respectively, for ALP activity assessment. Due to the CIS/ZnS QDs have an efficient excitation at 405 nm, meanwhile with a large Stokes shift emission at 588 nm, p-nitrophenol (PNP) with absorption peak at 405 nm, the hydrolyzed produce of PNPP and ALP, can act as a competitive absorber to absorb the excitation light of CIS/ZnS QDs, resulting in noticeable quenching of CIS/ZnS QDs. The proposed sensor detects ALP activity in human serum samples (sample consumption: 20 μL) with detection limit of 0.01 U L -1 . Excellent biocompatibility of CIS/ZnS QDs enables the sensor to monitor endogenous ALP in living cells. Furthermore, because the surface modification or the linking between the receptor and the fluorophore is no longer required, this fluorescent sensing system has the potential to simplify ALP clinical measurement, thereby improving diagnostics of relevant diseases., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Several solution-based methods have recently been adapted for use in paper substrates for enzymatic amplification to increase the number of copies of DNA sequences. There is limited information available about the impact of a paper matrix on DNA amplification by enzymatic processes, and about how to optimize conditions to maximize yields. The work reported herein provides insights about the impact of physicochemical properties of a paper matrix, using nuclease-assisted amplification by exonuclease III and nicking endonuclease Nt. Bbv, and a quantum dot (QD) - based Forster Resonance Energy Transfer (FRET) assay to monitor the extent of amplification. The influence of several properties of paper on amplification efficiency and kinetics were investigated, such as surface adsorption of reactants, and pore size. Additional factors that impact amplification processes such as target length and the packing density of oligonucleotide probes on the nanoparticle surfaces were also studied. The work provides guidance for development of more efficient enzymatic target-recycling DNA amplification methods in paper substrates., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Carbon quantum dots (CDs) have standout as one of the most important carbon nanomaterials owing to their small size, optical properties, biocompatibility and low toxicity. These CDs have been extensively explored for various applications especially in the biomedical fields. Although great efforts have been devoted to the fabrication of CDs through both top-down and bottom-up methods, most of these CDs exhibited blue emission under UV light irradiation. In this work, we reported a novel, green, economic approach for preparation of nitrogen doped CDs by directly microwave-assisted heating small organic molecules at 120°C for 5min using Glu and amino group of MPD as the precursors and ethylene glycol as solvent. Thus prepared CDs emit green fluorescence when they were irradiated under 365nm UV light. Compared with other synthetic methods, this microwave-assisted heating method does not require strict reaction conditions and is easy for operation. The CDs display unique luminescence properties, high water dispersibility and good biocompatibility. These remarkable features make CDs great potential for various biomedical applications. Taken together, a microwave-assisted heating method has been developed for bottom-up preparation of green emission CDs in a rather mild route. Owing to the facile experimental procedure and outstanding features of CDs, this work will open up a new avenue for fabrication and biomedical applications of CDs., (Copyright © 2017 Elsevier B.V. All rights reserved.)

We herein report an aqueous synthesis of gelatin stabilized CdTe/CdS/ZnS (CSSG) core/double shell quantum dots (QDs) with improved biocompatibility. The as-synthesized QDs were characterized by ultraviolet-visible (UV-vis) and photoluminescence (PL) spectroscopic techniques, x-ray diffraction technique (XRD), x-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The CSSG QDs revealed high photoluminescence quantum yield (PLQY) with excellent stability over a period of one year and retained 90% of its initial PLQY without any aggregation or precipitation under ambient condition. The cell viability study conducted on HeLa, cervical cancer cell lines indicated that the gelatin stabilization effectively decreased the QDs cytotoxicity by about 50%. The CSSG QDs were conjugated with transferrin (Tf) for the efficient delivery to the cancer cells followed by fluorescence imaging. The results showed that the CSSG QDs illuminates the entire cell which renders the QDs as cell labeling markers. The gelatin stabilized core/double shell QDs are potential candidates for long time fluorescent bio-imaging., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The purpose of this study was to determine the toxicity of two different sources of cadmium, i.e. CdCl 2 and Cd-based Quantum Dots (QDs), for freshwater model plant Lemna minor L. Cadmium telluride QDs were capped with two coating ligands: glutathione (GSH) or 3-mercaptopropionic acid (MPA). Growth rate inhibition and final biomass inhibition of L. minor after 168-h exposure were monitored as toxicity endpoints. Dose-response curves for Cd toxicity and EC50 168h values were statistically evaluated for all sources of Cd to uncover possible differences among the toxicities of tested compounds. Total Cd content and its bioaccumulation factors (BAFs) in L. minor after the exposure period were also determined to distinguish Cd bioaccumulation patterns with respect to different test compounds. Laser-Induced Breakdown Spectroscopy (LIBS) with lateral resolution of 200µm was employed in order to obtain two-dimensional maps of Cd spatial distribution in L. minor fronds. Our results show that GSH- and MPA-capped Cd-based QDs have similar toxicity for L. minor, but are significantly less toxic than CdCl 2 . However, both sources of Cd lead to similar patterns of Cd bioaccumulation and distribution in L. minor fronds. Our results are in line with previous reports that the main mediators of Cd toxicity and bioaccumulation in aquatic plants are Cd 2+ ions dissolved from Cd-based QDs., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Quantum dots (QDs) are semiconductor nanoparticles (NPs) that offer valuable functionality for cellular labeling, drug delivery, solar cells and quantum computation. In this study, we reported that CdSe QDs could be bio-synthesized in Bacillus licheniformis. After optimization, the obtained CdSe QDs exhibited a uniform particle size of 3.71±0.04nm with a maximum fluorescence emission wavelength at 550nm and the synthetical positive ratio can reach up to 87%. Spectral properties, constitution, particle sizes and crystalline phases of the CdSe QDs were systematically and integrally investigated. The CdSe QD-containing Bacillus licheniformis cells were further used as whole fluorescent bio-probes to detect copper (II) (Cu 2+ ) in water, which demonstrated a low limit of detection (0.91μM). The assay also showed a good selectivity for Cu 2+ over other ions including Al 3+ , Cd 2+ , Mg 2+ , K + , Na + , NH 4 + , Zn 2+ , CH 3 COO + , Pb 2+ and I - . Our study suggests the fluorescent CdSe QDs-containing Bacillus licheniformis bio-probes as a promising approach for detection of Cu 2+ in complex solution environment., (Copyright © 2017. Published by Elsevier Inc.)

Coupling of asymmetric flow field-flow fractionation (AF4) to an on-line elemental detection (inductively coupled plasma-mass spectrometry, ICP-MS) has been recently proposed as a powerful diagnostic tool for characterization of the bioconjugation of CdSe/ZnS core-shell Quantum Dots (QDs) to antibodies. Such approach has been used herein to demonstrate that cap exchange of the native hydrophobic shell of core/shell QDs with the bidentate dihydrolipoic acid ligands directly removes completely the eventual side nanoparticulated populations generated during simple one-pot synthesis, which can ruin the subsequent final bioapplication. The critical assessment of the chemical and physical purity of the surface-modified QDs achieved allows to explain the transmission electron microscopy findings obtained for the different nanoparticle surface modification assayed., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Nanoparticle (NP) interactions with biological tissues are affected by the size, shape and surface chemistry of the NPs. Here we use in vivo (zebrafish) and in vitro (HUVEC) models to investigate association of quantum dots (QDs) with endothelial cells and the effect of fluid flow. After injection into the developing zebrafish, circulating QDs associate with endothelium and penetrate surrounding tissue parenchyma over time. Amino-functionalized QDs cluster, interact with cells, and clear more rapidly than carboxy-functionalized QDs in vivo, highlighting charge influences. QDs show stronger accumulation in slow-flowing, small caliber venous vessels than in fast-flowing high caliber arterial vessels. Parallel-plate flow experiments with HUVEC support these findings, showing reduced QD-EC association with increasing flow. In vivo, flow arrest after nanoparticle injection still results in venous accumulation at 18 h. Overall our results suggest that both QD charge and blood flow modulate particle-endothelial cell interactions., (Copyright © 2016 Elsevier Inc. All rights reserved.)

The use of bacterial cells to produce fluorescent semiconductor nanoparticles (quantum dots, QDs) represents a green alternative with promising economic potential. In the present work, we report for the first time the biosynthesis of CdS QDs by acidophilic bacteria of the Acidithiobacillus genus. CdS QDs were obtained by exposing A. ferrooxidans, A. thiooxidans and A. caldus cells to sublethal Cd 2+ concentrations in the presence of cysteine and glutathione. The fluorescence of cadmium-exposed cells moves from green to red with incubation time, a characteristic property of QDs associated with nanocrystals growth. Biosynthesized nanoparticles (NPs) display an absorption peak at 360nm and a broad emission spectra between 450 and 650nm when excited at 370nm, both characteristic of CdS QDs. Average sizes of 6 and 10nm were determined for green and red NPs, respectively. The importance of cysteine and glutathione on QDs biosynthesis in Acidithiobacillus was related with the generation of H 2 S. Interestingly, QDs produced by acidophilic bacteria display high tolerance to acidic pH. Absorbance and fluorescence properties of QDs was not affected at pH 2.0, a condition that totally inhibits the fluorescence of QDs produced chemically or biosynthesized by mesophilic bacteria (stable until pH 4.5-5.0). Results presented here constitute the first report of the generation of QDs with improved properties by using extremophile microorganisms., (Copyright © 2016 Elsevier Inc. All rights reserved.)

SOX9 plays an important role in mesenchymal condensations during the early development of embryonic skeletons. However, its function in the chondrogenic differentiation of adult mesenchymal stem cells (MSCs) has not been fully investigated because SOX9 RNA interference in adult MSCs has seldom been studied. This study used SOX9 gene as the target gene and the quantum dot (QD)-based nanomaterial QD-NH 2 (ZnS shell and poly-ethylene glycol (PEG) coating) with a fluorescent tracer function as the gene carrier to transfect siSOX9 into MSCs after sulfosuccinimidyl-4-(N-maleimidomethyl) cyclohexane-1-carboxylate (sulfo-SMCC) activation in vitro and in vivo. The results showed that QD-SMCC could effectively bind and deliver siRNAs into the MSCs, followed by efficient siRNA escape from the endosomes. The siRNAs released from QD-SMCC retained their structural integrity and could effectively inhibit the targeted gene expression, leading to reduced chondrogenic differentiation of MSCs and delayed cartilage repair. QDs were excreted from living cells instead of dead cells, and the ZnS shell and PEG coating layer greatly reduced the cytotoxicity of the QDs. The transfection efficiency of QD-SMCC was superior to that of polyethylenimine (PEI). In addition, QD-SMCC has an intrinsic signal for noninvasive imaging of siRNA transport. The results indicate that SOX9 is imperative for the chondrogenesis of MSCs and QD-SMCC has great potential for real-time tracking of transfection., Statement of Significance: In this study, we developed functional quantum dot (QD) nanoplexes by sulfosuccinimidyl-4-(N-maleimidomethyl) cyclohexane-1-carboxylate (sulfo-SMCC) activation of PEG-coated CdSe/ZnS QDs as the gene carrier of siRNA to study the effect of SOX9 RNA interference on the chondrogenic differentiation of MSCs. This study confirmed the importance of SOX9 in chondrogenesis, as evidenced by the findings that SOX9 knockdown significantly inhibited the expression of cartilage-specific markers including acan and col2a1 in MSCs and further delayed cartilage repair. Moreover, QD-SMCC has an intrinsic signal for noninvasive imaging of siRNA transport. The results indicate that SOX9 is imperative for the chondrogenesis of MSCs and QD-SMCC has great potential for real-time tracking of transfection., (Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

We report an efficient method to biosynthesize biocompatible cadmium telluride and cadmium sulphide quantum dots from the fungus Rhizopus stolonifer. The suspension of the quantum dots exhibited purple and greenish-blue luminescence respectively upon UV light illumination. Photoluminescence spectroscopy, X-ray diffraction, and transmission electron microscopy confirms the formation of the quantum dots. From the photoluminescence spectrum the emission maxima is found to be 424 and 476nm respectively. The X-ray diffraction of the quantum dots matches with results reported in literature. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay for cell viability evaluation carried out on 3-days transfer, inoculum 3×10 5 cells, embryonic fibroblast cells lines shows that more than 80% of the cells are viable even after 48h, indicating the biocompatible nature of the quantum dots. A good contrast in imaging has been obtained upon incorporating the quantum dots in human breast adenocarcinoma Michigan Cancer Foundation-7 cell lines., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Quantum Dots (QDs) are promising very bright and stable fluorescent probes for optical studies in the biological field but water solubility and possible metal bio-contamination need to be addressed. In this work, a simple silica-QD hybrid system is prepared and the uptake in bovine chondrocytes living cells without any functionalization of the external protective silica shield is demonstrated. Moreover, long term treated cells vitality (up to 14days) and the transfer of silica-QDs to the next cell generations are here reported. Confocal fluorescence microscopy was also used to determine the morphology of the so labelled cells and the relative silica-QDs distribution. Finally, we employ silica-QD stained chondrocytes to characterize, as proof of concept, hydrogels obtained from an amphiphilic derivative of hyaluronic acid (HA-EDA-C18) functionalized with different amounts of the RGD peptide., (Copyright © 2016 Elsevier B.V. All rights reserved.)

This work carries out for the first time the comparison between the physical and chemical immobilization of choline oxidase onto aminated silica-based porous supports. The influence on the immobilization efficiency of concentration, pH, temperature and contact time between the support and choline oxidase, was evaluated. The immobilization efficiency was estimated taking into consideration the choline oxidase activity, which was assessed by using cadmium telluride (CdTe) quantum dots (QDs), obtained by hydrothermal synthesis, as photoluminescent probes. Hydrogen peroxide produced by enzyme activity was capable of quenching CdTe QDs photoluminescence. The magnitude of the PL quenching process was directly related with the enzyme activity. By comparing the chemical process with the physical adsorption, it was observed that the latter provided the highest choline oxidase immobilization. The equilibrium data were analyzed using Langmuir and Freundlich isotherms and kinetic data were fitted to the pseudo-first-order and pseudo-second-order models. Thermodynamic parameters, such as Gibbs free energy and entropy were also calculated. These results will certainly contribute to the development of new sensing schemes for choline, taking into account the growing demand for its quantification in biological samples., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Background: The oncogenesis of hepatocellular carcinoma (HCC) is not clear. The current methods of the pertinent studies are not precise and sensitive. The present study was to use liver cancer cell line to explore the bio-compatibility and cytotoxicity of ternary quantum dots (QDs) probe and to evaluate the possible application of QDs in HCC., Methods: CuInS2-ZnS-AFP fluorescence probe was designed and synthesized to label the liver cancer cell HepG2. The cytotoxicity of CuInS2-ZnS-AFP probe was evaluated by MTT experiments and flow cytometry., Results: The labeling experiments indicated that CuInS2-ZnS QDs conjugated with AFP antibody could enter HepG2 cells effectively and emit intensive yellow fluorescence by ultraviolet excitation without changing cellular morphology. Toxicity tests suggested that the cytotoxicity of CuInS2-ZnS-AFP probe was significantly lower than that of CdTe-ZnS-AFP probe (t test, F=0.8, T=-69.326, P<0.001). For CuInS2-ZnS-AFP probe, time-effect relationship was presented in intermediate concentration (>20%) groups (P<0.05) and dose-effect relationship was presented in almost all of the groups (P<0.05)., Conclusion: CuInS2-ZnS-AFP QDs probe had better bio-compatibility and lower cytotoxicity compared with CdTe-ZnS-AFP probe, and could be used for imaging the living cells in vitro.

A novel CdTe quantum dots (QDs) were prepared in aqueous phase via a facile method. At first, poly (acrylic amide) grafted onto sodium alginate (PAAm-g-SA) were successfully synthesized and then TGA capped CdTe QDs (CdTe-TGA QDs) were embed into it. The prepared CdTe-PAAm-g-SA QDs were optimized and characterized by transmission electron microscopy (TEM), thermo-gravimetric (TG) analysis, Fourier transform infrared (FT-IR), UV-vis and fluorescence spectroscopy. The characterization results indicated that CdTe-TGA QDs, with particles size of 2.90 nm, were uniformly dispersed on the chains of PAAm-g-SA biopolymer. CdTe-PAAm-g-SA QDs also exhibited excellent UV-vis absorption and high fluorescence intensity. To explore biological behavior of CdTe-PAAm-g-SA QDs, the interactions between CdTe-PAAm-g-SA QDs and human serum albumin (HSA) (or bovine serum albumin (BSA)) were investigated by cyclic voltammetry, FT-IR, UV-vis, and fluorescence spectroscopic. The results confirmed the formation of CdTe-PAAm-g-SA QDs-HSA (or BSA) complex with high binding affinities. The thermodynamic parameters (ΔG<0, ΔH<0 and ΔS<0) were indicated that binding reaction was spontaneous and van der Waals interactions and hydrogen-bond interactions played a major role in stabilizing the CdTe-PAAm-g-SA QDs-HSA (or BSA) complexes. The binding distance between CdTe-PAAm-g-SA QDs and HSA (or BSA)) was calculated about 1.37 nm and 1.27 nm, respectively, according to Forster non-radiative energy transfer theory (FRET). Analyzing FT-IR spectra showed that the formation of QDs-HSA and QDs-BSA complexes led to conformational changes of the HSA and BSA proteins. All these experimental results clarified the effective transportation and elimination of CdTe-PAAm-g-SA QDs in the body by binding to HSA and BSA, which could be a useful guideline for the estimation of QDs as a drug carrier., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Background Aims: Internalizing quantum dots (i-QDs) are a useful tool for tracking cells in vivo in models of tissue regeneration. We previously synthesized i-QDs by conjugating QDs with a unique internalizing antibody against a heat shock protein 70 family stress chaperone. In the present study, i-QDs were used to label rabbit mesenchymal stromal cells (MSCs) that were then transplanted into rabbits to assess differentiation potential in an osteonecrosis model., Methods: The i-QDs were taken up by bone marrow-derived MSCs collected from the iliac of 12-week-old Japanese white rabbits that were positive for cluster of differentiation (CD)81 and negative for CD34 and human leukocyte antigen DR. The average rate of i-QD internalization was 93.3%. At 4, 8, 12, and 24 weeks after transplantation, tissue repair was evaluated histologically and by epifluorescence and electron microscopy., Results: The i-QDs were detected at the margins of the drill holes and in the necrotized bone trabecular. There was significant colocalization of the i-QD signal in transplanted cells and markers of osteoblast and mineralization at 4, 8, and 12 weeks post-transplantation, while i-QDs were detected in areas of mineralization at 12 and 24 weeks post-transplantation. Moreover, i-QDs were observed in osteoblasts in regenerated tissue by electron microscopy, demonstrating that the tissue was derived from transplanted cells., Conclusion: These results indicate that transplanted MSCs can differentiate into osteoblasts and induce tissue repair in an osteonecrosis model and can be tracked over the long term by i-QD labeling., (Copyright © 2015 International Society for Cellular Therapy. Published by Elsevier Inc. All rights reserved.)

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., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Nanobiomaterials can be engineered to recognize cancer-specific receptors at the cellular level for diagnostic and therapeutic purposes. In this work, we report the synthesis of novel multifunctional nanoconjugates composed of fluorescent inorganic semiconductor quantum dot (QD) cores and tripeptide-modified polysaccharide organic shells. These structures were designed for targeting and imaging the αvβ3 integrin receptors of cancer cells. Initially, chitosan was covalently bound with the RGD peptide using a crosslinker to form bioconjugates (RGD-chitosan), which were later utilized as capping ligands for the production of surface-functionalized CdS QDs via a single-step process in aqueous media at room temperature. These core-shell nanostructures were extensively characterized by UV-vis spectroscopy, photoluminescence (PL) spectroscopy, Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), zeta potential (ZP) and dynamic light scattering (DLS). The TEM images and the UV-vis absorption results indicated the formation of ultra-small CdS QD nanocrystals with average diameters between 2.0 and 3.0 nm. In addition, the PL results demonstrated that the nanobioconjugates exhibited intense green fluorescence under excitation. The CdS-RGD-chitosan systems were effective at specific targeting integrin when assayed in vitro using two model cell cultures, HEK 293 (non-cancerous human embryonic kidney cell) and SAOS (cancerous sarcoma osteogenic-derived cells) imaged using fluorescence microscopy., (Copyright © 2015 Elsevier B.V. All rights reserved.)

The use of quantum dots (QDs) in biomedical applications is limited due to their inherent toxicity caused by the heavy metal core of the particles. Consequently, silicon-based QDs are expected to display diminished toxicity. We investigated the in vivo effects induced by Si/SiO2 QDs intraperitoneally injected in crucian carp liver. The QDs contained a crystalline Si core encased in a SiO2 shell, with a size between 2.75 and 11.25nm and possess intrinsic fluorescence (Ex 325nm/Em ∼690nm). Tissue fluorescence microscopy analysis revealed the presence of QDs in the liver for at least 2weeks after injection. Although protein and lipid oxidative stress markers showed the onset of oxidative stress, the hepatic tissue exhibited significant antioxidant adaptations (increase of antioxidant enzymes, recovery of glutathione levels), sustained by the activation of Hsp30 and Hsp70 chaperoning proteins. The increased activity of cyclooxigenase-2 (COX-2) and matrix metalloproteinases (MMPs) support the idea that Si/SiO2 QDs have a potential to induce inflammatory response, a scenario also indicated by the profile of Hsp60 and Hsp90 heat shock proteins. MMPs profile and the recovery of oxidative stress markers suggested a tissue remodelation phase after 3weeks from QDs administration., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)

In this study, we reported a convenient label-free fluorescence nanosensor for rapid detection of acid phosphatase on the basis of aggregation-caused quenching (ACQ) and enzymolysis approach. The selectivity nanosensor was based on the fluorescence "turn off-on" mode, which possessed high sensitivity features. The original strong fluorescence intensity of CuInS2 QDs was quenched by sodium hexametaphosphate (NaPO3)6. The high efficiency of the quenching was caused by the non-covalent binding of positively charged CuInS2 QDs to the negatively charged (NaPO3)6 through electrostatic interactions, aggregating to form a CuInS2 QDs/(NaPO3)6 complex. Adding acid phosphatase caused intense fluorescence of CuInS2 QDs/(NaPO3)6 to be recovered, and this was because of enzymolysis. (NaPO3)6 was hydrolyzed into small fragments and the high negative charge density decreased, which would weaken the strong electrostatic interactions. As a result, the quenched fluorescence "turned on". Under the optimum conditions, there was a good linear relationship between I/I0 (I and I0 were the fluorescence intensity of CuInS2 QDs/(NaPO3)6 system in the presence and absence of acid phosphatase, respectively) and acid phosphatase concentration in the range of 75-1500 nU mL(-1) with the detection limit of 9.02 nU mL(-1). The proposed nanosensor had been utilized to detect and accurately quantify acid phosphatase in human serum samples with satisfactory results., (Copyright © 2015 Elsevier B.V. All rights reserved.)

A new strategy for fabricating water-dispersible AgInS2 quantum dots (QDs) with bright near-infrared (NIR) emission is demonstrated. A type of multidentate polymer (MDP) was synthesized and utilized as a compact capping ligand for the AgInS2 QDs. Using silver nitrate, indium acetate and sulfur-hydrazine hydrate complex as the precursors, MDP-capping AgInS2 QDs were synthesized in aqueous solution at room temperature. Characterization indicates that the MDP-capping AgInS2 QDs are highly photoluminescent in NIR window and possess good photostability. Also, the QDs are stable in different media and have low cytotoxicity. Nude mice photoluminescence imaging shows that the MDP-capping AgInS2 QDs can be well applied to in vivo imaging. These readily prepared NIR fluorescent nanocrystals have huge potential for biomedical applications., (Copyright © 2014 Elsevier B.V. All rights reserved.)

CdTe quantum dots (QDs) were synthesized in aqueous solution using thioglycolic acid (TGA) as stabilizing agents. The interaction between TGA-CdTe QDs and fat mass and obesity-associated (FTO) protein was investigated by fluorescence, UV-visible absorption, synchronous fluorescence and three-dimensional fluorescence spectroscopy. Results revealed that TGA-CdTe QDs could strongly quench the intrinsic fluorescence of FTO protein with a static quenching procedure. Both the van der Waals and hydrogen bonding played a major role in stabilizing the complex. The binding constant and thermodynamic parameters at different temperatures were obtained. In addition, we found that the fluorescence intensity of QDs was significantly enhanced by the addition of FTO protein. Based on this, a sensitive method for detecting FTO protein was obtained in the linear range of 5.52×10(-9)-6.62×10(-7) mol L(-1) with the detection limit of 1.14×10(-9) mol L(-1). The influences of factors on the interaction between FTO protein and TGA-CdTe QDs were studied., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Daminozide (B9) is a growth inhibitor with important regulatory roles in plant growth and development. Locating and quantifying B9-binding proteins in plant tissues will assist in investigating the mechanism behind the signal transduction of B9. In this study, red fluorescent Mn-doped CdTe quantum dots (CdTeMn QDs) were synthesized by a high-temperature hydrothermal process. Since CdTeMn QDs possess a maximum fluorescence emission peak at 610nm, their fluorescence properties are more stable than those of CdTe QDs. A B9-CdTeMn probe was synthesized by coupling B9 with CdTeMn QDs. The fluorescence intensity of the probe is double that of CdTeMn QDs; its fluorescence stability is also superior under different ambient conditions. The probe retains the biological activity of B9 and is unaffected by interference from the green fluorescent protein present in plants. Therefore, we used this probe to label B9-binding proteins selectively in root tissue sections of mung bean seedlings. These proteins were observed predominantly on the surfaces of the cell membranes of the cortex and epidermal parenchyma., (Copyright © 2014 Elsevier B.V. All rights reserved.)

In the current work, using ZnSe ZnS quantum dots (QDs) as representative nanoparticles, the affinities of seven anticancer drugs for bovine serum albumin (BSA) were studied using fluorescence resonance energy transfer (FRET). The FRET efficiency of BSA-QD conjugates can reach as high as 24.87% by electrostatic interaction. The higher binding constant (3.63×10(7)Lmol(-1)) and number of binding sites (1.75) between ZnSe ZnS QDs and BSA demonstrated that the QDs could easily associate to plasma proteins and enhance the transport efficacy of drugs. The magnitude of binding constants (10(3)-10(6)Lmol(-1)), in the presence of QDs, was between drugs-BSA and drugs-QDs in agreement with common affinities of drugs for serum albumins (10(4)-10(6)Lmol(-1)) in vivo. ZnSe ZnS QDs significantly increased the affinities for BSA of Vorinostat (SAHA), Docetaxel (DOC), Carmustine (BCNU), Doxorubicin (Dox) and 10-Hydroxycamptothecin (HCPT). However, they slightly reduced the affinities of Vincristine (VCR) and Methotrexate (MTX) for BSA. The recent work will not only provide useful information for appropriately understanding the binding affinity and binding mechanism at the molecular level, but also illustrate the ZnSe ZnS QDs are perfect candidates for nanoscal drug delivery system (DDS)., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Preliminary results of a study of the interaction between 3-amino phenylboronic acid and glucose or ZnS:Cu quantum dots are presented in this paper. ZnS:Cu quantum dots with mercaptopropionic acid as a capping agent were obtained and characterized. Quenching of 3-amino phenylboronic acid fluorescence was studied by steady-state and timeresolved measurements. For fluorescence quenching with glucose the results of steady-state measurements fulfill Stern-Volmer equation. The quenching constants are increasing with growing pH. The decay of fluorescence is monoexponential with lifetime about 8.4 ns, which does not depend on pH and glucose concentration indicating static quenching. The quenching constant can be interpreted as apparent equilibrium constant of estrification of boronic group with diol. Quantum dots are also quenching 3-amino phenylboronic acid fluorescence. Fluorescence lifetime, in this case, is slightly decreasing with increasing concentration of quantum dots. The quenching constants are increasing slightly with pH's growth. Quenching mechanism of 3-amino phenylboronic acid fluorescence by quantum dots needs further experiments to be fully explained., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Nanoparticles have gained increasing interest in medical and in vivo applications. Metallothionein (MT) is well known as a maintainer of metal ions balance in intracellular space. This is due to high affinity of this protein to any reactive species including metals and reactive oxygen species. The purpose of this study was to determine the metallothionein-quantum dots interactions that were investigated by spectral and electrochemical techniques. CuS, CdS, PbS, and CdTe quantum dots (QDs) were analysed. The highest intensity was shown for CdTe, than for CdS measured by fluorescence. These results were supported by statistical analysis and considered as significant. Further, these interactions were analysed using gel electrophoresis, where MT aggregates forming after interactions with QDs were detected. Using differential pulse voltammetry Brdicka reaction, QDs and MT were studied. This method allowed us to confirm spectral results and, moreover, to observe the changes in MT structure causing new voltammetric peaks called X and Y, which enhanced with the prolonged time of interaction up to 6 h., (Copyright © 2014 Elsevier B.V. All rights reserved.)

This study details a novel method for the extracellular microbial synthesis of cadmium sulfide (CdS) quantum dots (QDs) by the white rot fungus Phanerochaete chrysosporium. P. chrysosporium was incubated in a solution containing cadmium nitrate tetrahydrate, which became yellow from 12h onwards, indicating the formation of CdS nanocrystals. The purified solution showed a maximum absorbance peak between 296 and 298 nm due to CdS particles in the quantum size regime. The fluorescence emission at 458 nm showed the blue fluorescence of the nanoparticles. X-ray analysis of the nanoparticles confirmed the production of CdS with a face-centered cubic (fcc) crystal structure. The average grain size of the nanoparticles was approximately 2.56 nm, as determined from the full width at half-maximum (FWHM) measurement of the most intense peak using Scherer's equation. Transmission electron microscopic analysis showed the nanoparticles to be of a uniform size with good crystallinity. The changes to the functional groups on the biomass surface were investigated through Fourier transform infrared spectroscopy. Furthermore, the secretion of cysteine and proteins was found to play an important role in the formation and stabilization of CdS QDs. In conclusion, our study outlines a chemical process for the molecular synthesis of CdS nanoparticles., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Quantum dots exhibit extraordinary optical and mechanical properties, and the number of their applications is increasing. In order to investigate a possible effect of coating on the inhalation toxicity of previously tested non-coated CdS/Cd(OH)2 quantum dots and translocation of these very small particles from the lungs, rats were exposed to coated quantum dots or CdCl2 aerosol (since Cd(2+) was present as impurity), 6h/d for 5 consecutive days. Cd content was determined in organs and excreta after the end of exposure and three weeks thereafter. Toxicity was determined by examination of broncho-alveolar lavage fluid and microscopic evaluation of the entire respiratory tract. There was no evidence for translocation of particles from the respiratory tract. Evidence of a minimal inflammatory process was observed by examination of broncho-alveolar lavage fluid. Microscopically, minimal to mild epithelial alteration was seen in the larynx. The effects observed with coated quantum dots, non-coated quantum dots and CdCl2 were comparable, indicating that quantum dots elicited no significant effects beyond the toxicity of the Cd(2+) ion itself. Compared to other compounds with larger particle size tested at similarly low concentrations, quantum dots caused much less pronounced toxicological effects. Therefore, the present data show that small particle sizes with corresponding high surfaces are not the only factor triggering the toxic response or translocation., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)

We describe here the synthesis, characterization, bioconjugation, and application of water-soluble thioglycolic acid TGA-capped CdTe/CdS quantum dots (TGA-QDs) for targeted cellular imaging. Anti-human epidermal growth factor receptor 2 (HER2) antibodies were conjugated to TGA-QDs to target HER2-overexpressing cancer cells. TGA-QDs and TGA-QDs/anti-HER2 bioconjugates were characterized by fluorescence and UV-Vis spectroscopy, X-ray diffraction (XRD), hydrodynamic sizing, electron microscopy, and gel electrophoresis. TGA-QDs and TGA-QDs/anti-HER2 were incubated with cells to examine cytotoxicity, targeting efficiency, and cellular localization. The cytotoxicity of particles was measured using an MTT assay and the no observable adverse effect concentration (NOAEC), 50% inhibitory concentration (IC50), and total lethal concentration (TLC) were calculated. To evaluate localization and targeting efficiency of TGA-QDs with or without antibodies, fluorescence microscopy and flow cytometry were performed. Our results indicate that antibody-conjugated TGA-QDs are well-suited for targeted cellular imaging studies., (Copyright © 2013 The Authors. Published by Elsevier B.V. All rights reserved.)

In order to assess cytotoxicity of quantum dots (QDs), new reliable analytical techniques that can provide comparative information at a single-cell level are required. In this study, a single cell ICP-MS (SC-ICP-MS) method was established to determine intracellular QDs in single cells after exposure. Uptake kinetics of QDs into cells was studied using the established method. The results were compared and validated by flow cytometry and cell digestion methods. In contrast to other methods, SC-ICP-MS can directly detect QDs and their degradation products via elements, and thus is a promising complement to available methods for single cell analysis and is expected to be a critical tool in the future., (© 2013 Elsevier B.V. All rights reserved.)

The photostability and narrow emission spectra of nonorganic quantum dot fluorophores make them desirable detection methods for ultrasensitive and multiplexing in situ hybridization applications to identify genetic aberrances in morphologically preserved clinical tissue specimens. However, robustness and reliability have not been fully investigated for quantum dot fluorophores in situ hybridization applications. We demonstrate the feasibility of an automated multiplexing four-color quantum dot fluorophores in situ hybridization assay comprised of four genomic probes each labeled with unique haptens, four anti-hapten antibodies each conjugated with quantum dot fluorophores with distinct emission spectrum, protocols for their use on a fully automated tissue staining platform, and direct observation of multiple signals using conventional filter-based fluorescent microscopy. This assay is successfully applied to the simultaneous detection of ERG3p, ERG5p, PTEN, and CEN10 genes in formalin-fixed, paraffin-embedded prostate tissues on BenchMark ULTRA instruments. There were 386 slides from 10 prostatectomy cases stained on 13 on these instruments. These 10 cases consisted of benign prostate and prostate cancer; the cancer cases were either positive or negative for ERG rearrangement and/or contained PTEN deletion. There were 350 (91%) slides appropriately stained for all four targets. The staining results accurately identified the ERG and PTEN status for all 10 cases. This approach is expected to enable multiplexing in situ detection of molecular biomarkers in routinely processed human clinical specimens., (Copyright © 2013 American Society for Investigative Pathology and the Association for Molecular Pathology. Published by Elsevier Inc. All rights reserved.)