Mn Quantum Dots Research Articles

Aquatic Fate and Ecotoxicology Effect of ZnS:Mn Quantum Dots on Chlorella vulgaris in Fresh Water.

With the increasing integration of nanomaterials into daily life, the potential ecotoxicological impacts of nanoparticles (NPs) have attracted increased attention from the scientific community. This study assessed the ecotoxicity of ZnS quantum dots (QDs) doped with varying molar concentrations of Mn2+ on Chlorella vulgaris. The ZnS:Mn QDs were synthesized using the polyol method. The size of the ZnS:Mn QDs ranged from approximately 1.1 nm to 2 nm, while the aggregation size in Seine River water was 341 nm at pH 6 and 8. The presence of ZnS:Mn (10%) NPs exhibited profound toxicity to Chlorella vulgaris, with immediate reductions in viability (survival cells) from 71%, 60% to 51%, 52% in BG11 and Seine River water, respectively, at a concentration of 100 mg L-1 of ZnS:Mn (10%) NPs. Additionally, the ATP content in Chlorella vulgaris significantly decreased in Seine River water (by 20%) after 3 h of exposure to ZnS:Mn (10%) NPs. Concurrently, SOD activity significantly increased in Seine River water, indicating that the ZnS:Mn (10%) NPs induced ROS production and triggered an oxidative stress response in microalgae cells.

Magnetic nanoparticles coated with a molecularly imprinted polymer via manganese-doped ZnS:Mn quantum dots for the determination of Triflumuron

ABSTRACT A novel multifunctional silica magnetic molecularly imprinted polymer (MQDs-MIPs) nanoparticle probe was synthesized for the rapid detection of triflumuron (TFM). The fluorescence probe consists of magnetite (Fe3O4) as a core and is wrapped with a molecularly imprinted polymer doped with Mn-doped ZnS quantum dots (QDs). Under optimal detection condition, the fluorescence quenching efficiency of MIP@Fe3O4@ZnS:Mn QDs displayed a linear relationship over the concentration range of 0–27.88 μmol/L with a correlation coefficient of 0.9947. Four structurally similar compounds were selected for selectivity testing and the nanocomposite showed good selectivity with a higher imprint factor of 2.52. This developed method has the advantages of simple preparation, fast response and low toxicity for trace TFM detection.

ZnS:Mn Quantum Dots Coated with a Silica Molecularly Imprinted Polymer for Trace Teflubenzuron Detection in Vegetable Samples.

A novel nanocomposite fluorescent probe consisting of quantum dots and a silica molecularly imprinted polymer (MIPs-capped ZnS:Mn QDs) was synthesized and applied for the rapid detection of teflubenzuron (TBZ) based on the fluorescence quenching of a composite probe via TBZ. The fluorescence quenching efficiency of MIP@SiO2@ZnS:Mn QDs displayed a linear relationship over the concentration range of 0-26.24μmol/L with a correlation coefficient of 0.9857 and the limit of detection was 2.4μg/L. The selectivity test showed that the nanocomposite had good selectively rebind TBZ with higher imprinting factor of 3.06 compared with four structurally similar compounds. In addition, the probe was successfully applied to the detection of TBZ in vegetable samples with a recovery of 90.3~97.1% and with a relative standard deviation below 3.2%. This developed method has the advantages of simple preparation, fast response and low toxicity for trace TBZ detection.

Biodegradable Nanocomposite of ZnS(Mn) Quantum Dots Immobilized Graphene Oxide for Bioimaging Applications.

Developing a biocompatible and biodegradable graphene-based fluorescent nanoprobe with the ability to visualize live cells could be interesting for intracellular imaging and monitoring the efficiency of chemotherapy. Herein, we report a biodegradable and biocompatible hybrid fluorescent graphene oxide (GO)-ZnS(Mn) composite synthesized via in situ growth of ZnS(Mn) quantum dots (QDs) on the surface of GO in the aqueous medium. The prepared 'GO-ZnS(Mn)' composite was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and high-resolution transmission electron microscopy (HR-TEM) along with selected area electron diffraction (SAED). Further, the fluorescence properties of the GO-ZnS(Mn) composite were studied using fluorescence emission spectroscopy. The composite material exhibited a strong and broad visible light fluorescence from 500 to 600 nm by excitation with 365 nm (UV) light. The cytotoxic experiments of folic acid (FA) conjugated GO-ZnS(Mn) using MTT [(3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide)] assay revealed that the composite had excellent biocompatibility even at higher concentrations up to 200 µg/mL in HeLa cell lines. Next, the bioimaging experiments carried out using confocal fluorescence laser scanning microscopy (CLSM) revealed that GO-ZnS(Mn) composite was taken up by the HeLa cells effectively within 12 h of incubation via receptor (folate) mediated endocytosis with strong fluorescence throughout the cell surface. Finally, the biodegradability of GO-ZnS(Mn) composite was studied by treating it with human myeloperoxidase enzyme (hMPO) isolated from the primary immune cells, neutrophils, which is important to understand the in vivo fate of GO-Zns(Mn). The HR-TEM and Raman analyses confirmed the biodegradation of GO-ZnS(Mn) within 15 h of hMPO treatment. Thus, the biodegradable GO-ZnS (Mn) composite could be helpful for chemotherapy and bioimaging applications.

Peptide-Functionalized ZnSe:Mn Quantum Dots as Fluorescent Probes for Accurate Localization of Hidden Dental Lesion Sites

Peptide-Functionalized ZnSe:Mn Quantum Dots as Fluorescent Probes for Accurate Localization of Hidden Dental Lesion Sites

Concentration-dependent dielectric and electro-optical properties of composites based on nematic liquid crystals and CdS:Mn quantum dots.

Composites in a wide concentration range of 0-0.6 wt% based on a nematic liquid crystal mixture and CdS quantum dots doped with manganese ions (Mn 6%) are presented. The effect of the CdS:Mn quantum dots on the phase diagram and electronic structure of composites was studied using differential scanning calorimetry and fluorescence analysis. Nonmonotonic concentration-dependent changes in the clearing point, which correlate with the fluorescence quenching behavior of the main CdS:Mn peak, were found. Dielectric spectroscopy and electro-optic studies revealed a corresponding increase in the dielectric permittivity anisotropy and birefringence in the 0.2-0.4 wt% range, where thermodynamic changes occur. The initiating factors behind this effect are supposed to be the self-assembly of quantum dots, and the distortion of the orientation order of liquid crystal molecules at a higher mass concentration of quantum dots.

Fabrication of a dye-based random laser using ZnS:Mn quantum dots and investigating the effects of their concentration

Zinc chalcogenide quantum dots (QDs) doped with paramagnetic transition metal ions (particularly ZnS:Mn QDs) are new attractive but rarely examined semiconductor nanocrystals that have excellent optical properties and enhanced thermal and environmental stability compared to Cd-based QDs. In this paper, we demonstrate a dye-based random laser (RL) with nonresonant feedback using ZnS:Mn QDs as the scattering medium that are dispersed in a Rhodamine B (RhB) dye solution. The nonlinear variation of the emission spectrum as a function of the excitation energy implies a random lasing threshold. Moreover, we observe a blue-shift of the emission wavelength by 10.3 nm and a 5.3 times decrease in the RL threshold by increasing the scatterer concentration. We also provide a theoretical discussion based on the diffusion theory for explaining the observed experimental results.

Highly Sensitive Broadband Photodetector Based on PbI2-Passivated CdS:Mn Quantum Dots with a Spectrally Flat Response

This paper has demonstrated the role of manganese (Mn) doping in cadmium sulfide (CdS) quantum dots (QDs) and their surface passivation for the fabrication of highly sensitive broadband photodetectors. These photodetectors have been fabricated in a p–n heterojunction geometry using the Mn-doped CdS (CdS:Mn) QDs with TiO2 nanoparticles. The thin film of CdS:Mn QDs has been passivated with lead iodide (PbI2) for faster charge transport and broadening of the spectral response of the device. Our detailed X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy indicate a partial PbS formation, which also causes spectral broadening. In addition, this passivation process enables us to enhance the photosensitivity of the device with a spectrally flat response of quantum efficiency throughout the visible range spectrum (350–700 nm). This work also demonstrated that the photosensitivity of the device gradually increases with Mn doping with a faster photoresponse. The highest detectivity of the device was obtained with 4% Mn-doped dots with a value of ∼3.9 × 1012 Jones under −0.5 V external bias with a photoresponse time of 0.2 s, indicating its very high detectivity with a fast response.

Integration of quantum dots with Zn2GeO4 nanoellipsoids to expand the dynamic detection range of uranyl ions in fluorescent test strips

Fluorescent colorimetric test strips normally have a narrow dynamic detection–range due to the limited responsive range from single responsive materials, which cannot meet the wide detection requirement in practical applications. Herein, we developed an approach to detect uranyl ions (UO22+) with a broad detection range using the synthesized ZnS:Mn quantum dots (QDs) modified Zn2GeO4 nanoellipsoids (Zn2GeO4 @ZnS:Mn NEs), containing two responsive materials with the opposite signal responses at different UO22+ concentrations. Specifically, a red to chocolate color change was observed at low analyte concentrations (0.01–100 μM) resulting from the photoinduced electron transfer effect from ZnS:Mn QDs to UO22+. A sequentially olive drab to green color change has been observed when further increasing the UO22+ concentration (100–1000 μM) as a result of the antenna effect between Zn2GeO4 nanoellipsoids and UO22+. In addition, a low-cost and portable fluorescent test strip has been further fabricated through embedding Zn2GeO4 @ZnS:Mn NEs on a microporous structure membrane, demonstrating a facile yet effective colorimetric response to UO22+ in lab water, lake water, and seawater with a wide dynamic range. Therefore, it is potentially attractive for real-time and on-site detection of UO22+ in sudden-onset situations.

Quantum dots and its advancement in the treatment of Parkinson’s disease: a review

Quantum dots also known as zero-dimensional Nano materials, which have very distinctive Properties Such as Electro chemiluminescent, Fluorescent, Photoluminescent. because of their unique properties quantum dots have a revolutionary role in Biomedical research. Quantum dots Like Zinc oxide quantum dots, Graphene Quantum dots, Glutathione conjugated carbon quantum dots (GSH-CQDs) and L-cysteine capped ZnS:Mn quantum dots have many applications in diagnosis and treatment. They can easily cross blood brain barrier hence they be used as drug carriers further more because of their capabilities they gather widespread attention in the biomedical research.

Bright, Magnetic NIR-II Quantum Dot Probe for Sensitive Dual-Modality Imaging and Intensive Combination Therapy of Cancer.

Improving the effectiveness of cancer therapy will require tools that enable more specific cancer targeting and improved tumor visualization. Theranostics have the potential for improving cancer care because of their ability to serve as both diagnostics and therapeutics; however, their diagnostic potential is often limited by tissue-associated light absorption and scattering. Herein, we develop CuInSe2@ZnS:Mn quantum dots (QDs) with intrinsic multifunctionality that both enable the accurate localization of small metastases and act as potent tumor ablation agents. By leveraging the growth kinetics of a ZnS shell on a biocompatible CuInSe2 core, Mn doping, and folic acid functionalization, we produce biocompatible QDs with high near-infrared (NIR)-II fluorescence efficiency up to 31.2%, high contrast on magnetic resonance imaging (MRI), and preferential distribution in 4T1 breast cancer tumors. MRI-enabled contrast of these nanoprobes is sufficient to timely identify small metastases in the lungs, which is critically important for preventing cancer spreading and recurrence. Further, exciting tumor-resident QDs with NIR light produces both fluorescence for tumor visualization through radiative recombination pathways as well as heat and radicals through nonradiative recombination pathways that kill cancer cells and initiate an anticancer immune response, which eliminates tumor and prevents tumor regrowth in 80% of mice.

Functional codoped ZnSe:Cu, Mn quantum dots(QDs): Microstructure, calorimetric and photoluminescence properties

In the present work, undoped ZnSe, and Zn1-x-y Cux Mny Se (x = 0.001, y = 0, 0.001, 0.010 0.015, 0.02 and 0.04 mol) codoped-quantum dots (cdQDs) of mean crystallite size within the range of 1.12 to 1.63 nm are synthesized employing the simple microwave irradiation (MWIR) assisted method; Different synthesis regimes of variable MWIR times and also Mn content are performed for ZnSe:Cu-Mn QDs. Structural, optical properties and melting point of the as-synthesized ZnSe QDs are studied by XRD, FESEM equipped with EDX and Map, TEM, Fourier transform infrared (FTIR) and differential scanning calorimetry (DSC) analysis. XRD confirms the incorporation of Mn and Cu in ZnSe structure with the tunable size by changing the synthesize conditions; TEM results indicate spherical particles, most of which had a diameter of about 5 nm. Results of photoluminescence (PL) investigations show the synthesis condition dependence nature of the samples, suggesting their application in green-region sensors/biosensors; Mn doping causes more extent of PL in to the light wavelengths; doping with transition metals (TMs) impurities and employing MWIR cause an enhancement in the intensity and peak shift of PL band toward higher wavelengths, which influence on the optical properties of semiconductors. The FTIR absorption peaks for the understudied samples show the formation of ZnSe structure (the interaction between Se2− and Zn2+ ions) and insertion of Mn and Cu ions into their lattices; The Experimental and empirical melting temperature of synthesized nanomaterial are investigated; DSC analysis shows that nanoparticles melting point of the present nanoparticles are 600 °C lower than that of the bulk ZnSe owing melting point of 1520–1525 °C. Empirical size dependency of melting point shows that at lower than the Bohr radius of ZnSe (~8 nm), reasonable fast decrease in melting point occurs.

Multi-photon-excited fluorescence resonance energy transfer in an aqueous system from ZnSe:Mn and ZnSe quantum dots to Rhodamine 6G

Multi-photon-excited fluorescence resonance energy transfer in an aqueous system from ZnSe:Mn and ZnSe quantum dots to Rhodamine 6G

Bio-synthesised Silver Nanoparticle-Conjugated l-Cysteine Ceiled Mn:ZnS Quantum Dots for Eco-friendly Biosensor and Antimicrobial Applications

The present work deals with the green synthesis of silver nanoparticles (Ag NPs) from bio-reduction of Ag nitrate using different concentrations of medicinal plant extracts, namely, Mentha arvensis, Bryophyllum pinnatum and Dalbergia sissoo. The bio-synthesis route with a non-toxic approach is an attractive research topic in the area of nano-biomedicine and material science. Eco-friendly Ag NPs have been confirmed from the brown color of the solutions, and via UV–Vis spectroscopy. Further, Ag NP-conjugated l-cysteine capped ZnS:Mn quantum dots have been developed successfully. This prepared conjugation aims at antimicrobial activity using antibiotic-resistant gram-positive and gram-negative bacteria, namely, Staphylococcus aureus and Escherichia coli, respectively. In anti-microbial studies, a zone of inhibition (antibiotic sensitivity) was found to vary significantly with the varied concentration of Ag NPs that also depends on the specific type of plant extract. These studies may open the door for non-toxic material to synthesize plasmonic NPs for biosensors and detectors.

Construction of a room-temperature phosphorescent quantum dot probe and quantitative detection of thyroxine and carbamazepine

In this paper, a new quantitative detection system for thyroxine (T4) and carbamazepine (CBZ) was constructed. A mixture of MPA-capped Mn and ZnS quantum dots (MPA-Mn:ZnS QDs) exhibiting room-temperature phosphorescence (RTP) was prepared, which serves as the detection signal. The hexadecyltrimethylammonium bromide/ MPA-Mn:ZnS QDs (CTAB/QD) compound binds T4 to produce a CTAB/QDs&T4 complex, which results in phosphorescent quenching of the quantum dots. By adding CBZ to CTAB/QDs&T4, the phosphorescent quenching remains, allowing the quantitative detection of T4 and CBZ. Under the best experimental conditions, the linear relationship of QDs/CTAB-T4 is T4△RTP=0.4137CT4+0.1034, the correlation coefficient is R2=0.999, the detection limit is 1.95 nmol/L, and the detection range is 4.85 nmol/L to 1.59 μmol/L; the linear relationship of CTAB/QDs&T4CBZ is CBZ△RTP=0.4178x+0.112, the correlation coefficient is R2=0.995, the detection limit is 3.43 nmol/L and the detection range is 7.9 nmol/L to 1.555 μmol/L. This method has many advantages, such as anti-interference (which can overcome the autofluorescence interference of biological samples), nontoxicity, sensitivity, simple operation and low cost, and can be applied to the quantitative detection of T4 and CBZ in human serum samples.

Highly luminescent ZnS:Mn quantum dots capped with aloe vera extract

This study demonstrates the optical properties of ZnS:Mn2+ qquantum dots synthesized by simple and eco-friendly chemical precipitation method using aloe vera (AV) extract as the stabilizing agent. The nanoparticles have been characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, diffuse reflectance spectroscopy (DRS), photoluminescence (PL) and time-resolved PL spectroscopy. Increase in band gap energy with decrease in particle size was observed from DRS studies due to quantum confinement effect. Dominant yellow emission was observed from characteristic 4T1→6A1 transitions of the Mn2+ions in the ZnS:Mn/AV nanoparticles. The results provide insight to the quantum confinement effect that occur and how it affect decay life time of the ZnS:Mn2+/AV nanoparticles.

The study of chiral recognition on ibuprofen enantiomers by a fluorescent probe based on β-cyclodextrin modified ZnS:Mn quantum dots

In this paper, a fluorescence method for chiral detection of ibuprofen and its enantiomer was developed. The L-cystenine-capped ZnS:Mn quantum dots were synthesized and functionalized with β-cyclodextrin (β-CD-QDs). The β-CD-QDs exhibited different quenching effect to the S-(+)-ibuprofen and the R-(-)-ibuprofen based on the advantage of the inclusion complex of cyclodextrin. It was found that the quenching of β-CD-QDs by S-(+)-ibuprofen was due to the formation of inclusion complex through both static quenching and photoinduced electron transfer, but only slight quenching with the R-(-)-ibuprofen. The stability constants derived from Hildebrand-Benesi method and absorption titration experiments were applied to determine the stability constants of the formed complexes, the double reciprocal plots suggest that a conclusion complex with a ratio of 1:1 was formed between β-CD-QDs and S-(+)-ibuprofen, but did not with the R-(-)-ibuprofen. The fluorescence intensity of the β-CD-QDs was linearly dependent on the concentration of the S-(+)-IBP in the range of 0-0.5 nmol/L with an limit of detection of 0.29 nmol/L.

Ionic liquid-sensitized molecularly imprinted polymers based on heteroatom co-doped quantum dots functionalized graphene for sensitive detection of λ-cyhalothrin

Ionic liquid-sensitized molecularly imprinted polymers (MIPs) based on Mn and Cu co-doped ZnIn2S4 quantum dots functionalized graphene (QDs-G@ILMIPs) were prepared by a one-pot facile polymerization at room temperature. Here, the ionic liquid was used as functional monomers to provide chemical bonds for the recognition sites of target molecules. The ionic liquid was also used to improve the selectivity and adsorption capacity, and enhance the fluorescence stability and sensitivity of the MIPs for surface modification. Additionally, the Mn/Cu co-doped ZnIn2S4 quantum dots could play a synergistic role in avoiding the toxicity of the heavy metals, and enhance the fluorescence performance. An increased efficiency and sensitivity of QDs-G@ILMIPs was obtained owing to the use of graphene with its large specific surface area, which effectively increased the number of binding sites to facilitate the electron transfer process. The turn-off fluorescence spectra of QDs-G@ILMIPs decreased sharply with an increasing concentration of the λ-cyhalothrin standards within the range from 1 to 350 μg g−1. The detection limit of QDs-G@ILMIPs was 0.246 μg g−1. Furthermore, the QDs-G@ILMIPs toward λ-cyhalothrin detection in real samples, as well as its recovery, reproducibility and stability, proved that the QDs-G@ILMIPs could be extensively applied for the accurate detection of pesticide residues in food samples.

Ultrasensitive electrochemiluminescence biosensing platform for miRNA-21 and MUC1 detection based on dual catalytic hairpin assembly.

Multi-target detection has been widely applied for the sensitive measurement of cancer-related biomarkers; however, the design and application of single platforms for diverse target detection are still challenging. Herein, a robust and sensitive electrochemiluminescence (ECL) biosensing platform was constructed for the measurement of microRNA-21 (miRNA-21) and mucin 1 (MUC1) based on dual catalytic hairpin assembly (DCHA). The catalytic hairpin assembly (CHA) process (Cycle I) was initiated by the target miRNA-21 to introduce abundant CdS:Mn quantum dots (CdS:Mn QDs) on the electrode surface, leading to a considerable ECL response and the sensitive detection of miRNA-21 with a limit of detection as low as 11 aM. Subsequently, the second CHA process (Cycle II) was triggered by the MUC1-aptamer complex, which allowed copious amounts of Au nanoparticles (AuNPs) to approach the CdS:Mn QDs. A decreased ECL signal was obtained due to the ECL resonance energy transfer (ECL-RET) effect between the CdS:Mn QDs and AuNPs; meanwhile, MUC1 was sensitively detected with a limit of detection of 0.40fgmL-1. This single sensing platform achieved dual cancer-related biomarker detection, which could provide a rational approach for future clinical analyse.

Suppression of blue photoluminescence and enhancement of green photoluminescence by Mn and Cu Co-doped ZnS quantum dots

ZnS is a good candidate material for making visible light display devices. However, the blue emission of ZnS is so strong in luminescence spectra that it may harm human eyes. In this paper, we prepared the Mn and Cu co-doped ZnS quantum dots, which successfully decreased the blue photoluminescence without producing any Mn-related yellow–orange emissions, and obviously enhanced the eyes-friendly green photoluminescence at the same time. The relevant physical mechanisms have been discussed in detail. Overall, this paper realizes the suppression of blue photoluminescence and enhancement of green photoluminescence of ZnS, thereby the center of whole photoluminescence spectra of ZnS is transferred successfully from blue to green, showing a bright prospect for the application in visible display devices.