Manganese-doped Zinc Sulfide Quantum Research Articles

Development of inexpensive device for methanol detection in hand sanitizer gel using manganese-doped zinc sulfide quantum dots modified by N-methylpolypyrrole

A method for methanol detection by an inexpensive device using a nanomaterial modified by N-methylpolypyrrole (NMPPY) has been developed. Manganese-doped zinc sulfide quantum dots (Mn/ZnS-QDs) were synthesized and then characterized by a fluorescence spectrophotometer to study their spectroscopic properties. Mn/ZnS-QDs were modified with NMPPy and studied by digital-image colorimetry to optimize conditions for methanol detection. A 2 mL of 3000 mg∙L–1 Mn/ZnS-QDs modified with 300 μL of 1000 mg∙L-1 of NMPPy was chosen to be a detecting reagent for methanol determination. Under the optimum conditions, the linear range was found to be 2%v/v to 50%v/v of methanol with R-square of 0.9434 and the sensitivity of 3.569 ´ 10–3 (%v/v)-1, whilst the limit of detection (LOD) was 19.5%v/v. The selectivity of this method was also studied with several solvents; it was proven selective for methanol. Furthermore, a prototype device with simple and inexpensive has been created. The analytical performances were studied; the linearity of methanol detection was found in the range of 20%v/v to 80%v/v with R-square of 0.9918 and the sensitivity of 3.38 ´ 10-3 (%v/v)-1. Finally, the newly developed device was applied to analyze samples of hand sanitizer gel by digital-image colorimetry with acceptable results.

Molecular Imprinted ZnS Quantum Dots-Based Sensor for Selective Sulfanilamide Detection

Combining molecular imprinted polymers and water-soluble manganese-doped zinc sulfide quantum dots (Mn2+: ZnS QDs), a new molecule imprinted polymers-based fluorescence sensor was designed. The molecule imprinted quantum dots (MIP@QDs) were constructed by coating molecular imprinted polymers layer on the surface of ZnS: Mn2+ QDs using the surface molecular imprinting technology. The developed MIP@QDs-based sensor was used for rapid and selective fluorescence sensing of sulfanilamide in water samples. The binding experiments showed that the MIP@QDs has rapid fluorescent responses, which are highly selective of and sensitive to the detection of sulfanilamide. The respond time of the MIP@QDs was 5 min, and the imprinting factor was 14.8. Under optimal conditions, the developed MIP@QDs-based sensor shows a good linearity (R2 = 0.9916) over a sulfanilamide concentration range from 2.90 × 10−8 to 2.90 × 10−6 mol L−1, with a detection limit of 3.23 × 10−9 mol L−1. Furthermore, the proposed MIP@QDs-based sensor was applied to the determination of sulfanilamide in real samples, with recoveries of 96.80%–104.33%, exhibiting good recyclability and stability. Experimental results showed that the prepared MIP@QDs has the potential to serve as a selective and sensitive sensor for the fluorescence sensing of sulfonamides in water samples.

Synthesis and characterization of 2-mercaptoethanol-capped manganese-doped zinc sulfide quantum dots-embedded molecularly-imprinted membranes

The objective of this study is to synthesize QD-embedded molecularly imprinted membranes (MIMs) with 2-mercaptoethanol-capped manganese-doped zinc sulfide quantum dots (ME-capped Mn-doped ZnS QDs) through chemical precipitation followed by surface molecular imprinting. For the synthesis of the MIMs, the weight of ME-capped Mn-doped ZnS QDs was first manipulated, followed by their characterization through transmission electron microscopy (TEM), zeta potential, hydrodynamic particle size, particle size distribution, and Fourier-transform infrared spectroscopy (FTIR). The resultant MIM was characterized by fluorescence intensity and showed an emission peak of 600 nm with an excitation wavelength of 300 nm. Besides, increments in QDs were found to elevate the fluorescence intensity of the MIM, contributing to an improved fluorescence quantum yield. This article indicates that molecularly-imprinted QD-based sensors offer promising biomedical potential in diagnoses and treatment.

Triple-dimensional spectroscopy combined with chemometrics for the discrimination of pesticide residues based on ionic liquid-stabilized Mn-ZnS quantum dots and covalent organic frameworks

Manganese-doped zinc sulfide quantum dots (Mn-ZnS QDs) are promising candidates for multi-channel sensing analysis due to their multi-dimensional optical properties. In this study, we integrated amino-silane and ionic liquid co-modified Mn-ZnS QDs and covalent organic frameworks (COFs) into optosensing nanoparticles to provide triple-dimensional optical response signals and combined them with chemometrics for the analysis of multiple pesticide residues. Through the exploration and optimization of a series of conditions, fluorescence, room temperature phosphorescence, and ultraviolet−visible combined with chemometrics were used for the discrimination and recognition of multiple pesticide residues in fruits and vegetables. The ionic liquid of 1-vinyl-3-ethylimidazolium tetrafluoroborate was used to modify Mn-ZnS QDs to improve the optical response and enrichment of pesticide adsorption sites, which were also synergistically enhanced by the COF support. This is a potential method to discriminate pesticides efficiently and enables fast and reliable analysis of pesticides in the agricultural and food industries.

One Pot Aqueous Synthesis of L-Histidine Amino Acid Capped Mn: ZnS Quantum Dots for Dopamine Sensing

Background: Mn doped ZnS is selected as the right element which is prominent among quantum dot for its high luminescent and quantum yield property and also non toxicity while comparing with other organometallic quantum dot synthesized by using different capping agents. Methods: An interesting observation based on colorimetric sensing of dopamine using manganese doped zinc sulfide quantum dot is discussed in this study. Mn doped ZnS quantum dot surface passivated with capping agents such as L-histidine and also in polymers like chitosan, PVA and PVP were studied and compared. The tunable fluorescence effect was also observed in different polymers and amino acid as capping agents. Optical characterization studies like UV-Visible spectroscopy and PL spectroscopy have been carried out. The functional group modification of Quantum dot has been analyzed using FTIR and size and shape analysis was conducted by using HRTEM image. Result: The strong and broad peak of FTIR in the range of 3500-3300 cm-1 confirms the presence of O-H bond. It is also observed that quenching phenomena in the luminescent peak are due to weaker confinement effect. The average size of the particle is shown to be around 4-5 nm. Changes in color of the quantum dot solution from transparent to dark brown has been due to the interaction with dopamine. Conclusion: Finally, L-Histidine amino acid capped Mn:ZnS shows better results in luminescence and size confinement properties. Hence, it was chosen for dopamine sensing due to its colloidal nature and inborn affinity towards dopamine, a neurotransmitter which is essential for early diagnosis of neural diseases

Application of Zinc Sulfide Quantum Dots for Optical Sensing

The luminescent sensory systems based on manganese-doped zinc sulfide quantum dots were developed for aqueous environment monitoring. The structural, optical and sensory characteristics of quantum dots were investigated. The mechanism of ZnS:Mn2+ interaction with methane in the aqueous media, as well as factors that have a primary influence on the formation of the sensory response in the reaction with methane, were determined.

Manganese Doped Zinc Sulfide Quantum Dots as Efficient Photocatalyst for Dye Decolorization

A simple aqueous based synthesis technique at room temperature was performed for preparation of pure and manganese (Mn2+) doped ZnS quantum dots in the presence of glutathione as the capping agent. Under UV-excitation quantum dots show photoluminescence bands at 2.13 and 3.0 eV corresponded to Mn2+ and intrinsic ZnS emission respectively. ZnS quantum dots were used as the photocatalyst to remove organic dyes in aqueous solution, with methylene blue as a model dye. The influence of the Mn2+ concentration on the dye degradation efficiency was studied. The highest photocatalytic degradation rate of methylene blue was obtained for ZnS quantum dots in glutathione shell doped with 0.125 at % of Mn2+.

Luminescent Methane Sensor Based on Energy Transfer from ZnS:Mn2+ Quantum Dots to Analyte Molecule

Manganese-doped zinc sulfide quantum dots were synthesized by chemical precipitation in an aqueous solution in the presence of glutathione as the capping agent. Obtained samples show dual emission band with maximums at 2.11 eV (Mn2+) and about 3.1 eV (intrinsic defects of ZnS QDs). Under exposure to methane in the concentration range from 100 to 2000 ppm the ZnS:Mn2+ emission spectrum is changed significantly. It was shown, the luminescent sensor response occurs due to photoinduced electron transfer from QDs to methane molecule resulting in QD luminescence quenching and luminescence lifetime decreasing.

Sensing and photocatalytic activity of zinc sulfide quantum dots based on charge transfer process to analyte molecule

We demonstrated the efficientcharge transfer between manganese doped zinc sulfide quantum dots (QDs)and an analyte molecule, methaneor methylene blue dye, by means of photoluminescence properties of ZnS QDs. In the presenceof methane QDs arefound to exhibit non-uniform increasing of luminescence intensity due to specific charge transfer from analyte to QD defect states. It is revealed that charge transfer leads to destruction of methylene blue dye molecule which makes possible to use the QDs for organic dye removal in aqueous solution. The limit of methane detection is 100 ppm. The photocatalytic rate of methylene blue degradation is 0.033 s−1 which is almost two orders higher than Degussa P25 rate.

Manganese-Doped Zinc Sulfide Quantum Dots for Methane Detection in Aqueous Media

A simple aqueous based synthesis technique at room temperature was performed for preparation manganese-doped zinc sulfide quantum dots. Under 4 eV excitation quantum dots show photoluminescence bands at 2.11 and 3.1 eV corresponded to Mn2+and intrinsic ZnS emission respectively. ZnS quantum dots were used as the luminescent sensing element for methane detection in aqueous media. The luminescent sensor response occurs due to photoinduced electron transfer from QDs to methane molecule resulting in QD luminescence quenching.

Graphene Oxide/ZnS:Mn Nanocomposite Functionalized with Folic Acid as a Nontoxic and Effective Theranostic Platform for Breast Cancer Treatment.

Nanoparticle-based cancer theranostic agents generally suffer of poor dispersability in biological media, re-agglomeration over time, and toxicity concerns. To address these challenges, we developed a nanocomposite consisting of chemically-reduced graphene oxide combined with manganese-doped zinc sulfide quantum dots and functionalized with folic acid (FA-rGO/ZnS:Mn). We studied the dispersion stability, Doxorubicin (DOX) loading and release efficiency, target specificity, internalization, and biocompatibility of FA-rGO/ZnS:Mn against folate-rich breast cancer cells, and compared to its uncoated counterpart (rGO/ZnS:Mn). The results indicate that DOX is adsorbed on the graphene surface via π–π stacking and hydrophobic interaction, with enhanced loading (~35%) and entrapment (~60%) efficiency that are associated to the chelation of DOX and surface Zn2+ ions. DOX release is favored under acidic conditions reaching a release of up to 95% after 70 h. Membrane integrity of the cells assessed by Lactate dehydrogenase (LDH) release indicate that the surface passivation caused by folic acid (FA) functionalization decreases the strong hydrophobic interaction between the cell membrane wall and the edges/corners of graphene flakes. Chemotherapeutic effect assays reveal that the cancer cell viability was reduced up to ~50% at 3 µg/mL of DOX-FA-rGO/ZnS:Mn exposure, which is more pronounced than those obtained for free DOX at the same doses. Moreover, DOX-rGO/ZnS:Mn did not show any signs of toxicity. An opposite trend was observed for cells that do not overexpress the folate receptors, indicating that FA functionalization endows rGO/ZnS:Mn with an effective ability to discriminate positive folate receptor cancerous cells, enhancing its drug loading/release efficiency as a compact drug delivery system (DDS). This study paves the way for the potential use of functionalized rGO/ZnS:Mn nanocomposite as a platform for targeted cancer treatment.

A two-dimensional sensing device based on manganese doped zinc sulfide quantum dots for discrimination and identification of common sugars

A Mn-doped ZnS QD 2D sensor for identification and separation of common sugars.

Phosphorescence detection of manganese(VII) based on Mn-doped ZnS quantum dots

The phosphorescent l-cysteine modified manganese-doped zinc sulfide quantum dots (l-cys-MnZnS QDs) was developed for a highly sensitive detection of permanganate anions (MnO4−). l-cys-MnZnS QDs, which were easily synthesized in aqueous media using safe and low-cost materials, can emit intense phosphorescence even though the solution was not deoxygenated. However, the phosphorescence of l-cys-Mn-ZnS QDs was strongly quenched by MnO4− ascribed to the oxidation of l-cys and the increase of surface defects on l-cys-MnZnS QDs. Under the optimal conditions, l-cys-MnZnS QDs offer high selectivity over other anions for MnO4− determination, and good linear Stern-Volmer equation was obtained for MnO4− in the range of 0.5–100μM with a detection limit down to 0.24μM. The developed method was finally applied to the detection of MnO4− in water samples, and the spike-recoveries fell in the range of 95–106%.

Optical sensing of 3-phenoxybenzoic acid as a pyrethroid pesticides exposure marker by surface imprinting polymer capped on manganese-doped zinc sulfide quantum dots

The present communication deals with the synthesis of luminescent Mn-doped ZnS quantum dots (QDs) anchored to surface imprinted polymer for the optical sensing of 3-phenoxy benzoic acid (3-PBA) in urine samples. The combination of sensing and surface functionalization not only improves the selectivity of the method, but also increases the optosensing ability of the material for non-phosphorescent substances. The developed material was utilized for the selective and sensitive detection of 3-PBA in urine samples. The proposed method shows good linearity with a regression coefficient (R2) of 0.98. The limit of detection was found to be 0.117μM. The method has an acceptable precision and accuracy which are found to be less than 8% and 80–90% respectively at three different concentrations. The quenching constant of quantum dot-molecular imprinted polymer was found to be 3.4 times higher to that of the quantum dot-non imprinted polymer (QD-NIP) as calculated by Stern–Volmer equation. The sensing method developed has shown immense utility to detect 3-PBA in complex biological samples like urine.

Surface Molecular Imprinting on Manganese-Doped Zinc Sulfide Quantum Dots for Fluorescence Detection of Bisphenol A in Water

Manganese-doped zinc sulfide quantum dot based molecularly imprinted polymer composite nanoparticles were prepared. Bisphenol A served as the template and 3-aminopropyltriethoxysilane and tetraethoxysilicane were the functional monomer and cross-linker, respectively. The quantum dots exhibited excellent selectivity, fast adsorption kinetics, high stability, and good dispersion in aqueous media. The quenched fluorescence emission was proportional to the concentration of Bisphenol A without any preconcentration. This highly selective fluorescence sensor had a linear response from 10 to 700 nanograms per milliliter with a correlation coefficient of 0.9860. The relative standard deviation of five replicate measurements of 100 nanograms per milliliter Bisphenol A was 2.2 percent. The recovery of fortified Bisphenol A in water samples ranged from 98.70 to 105.50 percent.

Selective room temperature phosphorescence detection of heparin based on manganese-doped zinc sulfide quantum dots/polybrene self-assembled nanosensor

A selective system was developed to detect heparin in aqueous solutions by using MPA(3-Mercaptopropionic Acid)-capped Mn-doped ZnS quantum dots (QDs)/polybrene (hexadimethrine bromide) hybrids as a sensitive room temperature phosphorescence (RTP) nanosensor. In this system, the RTP intensity of QDs was remarkably enhanced via electrostatic self-assembly after the addition of polybrene. The addition of heparin into the system was competitively bound to polybrene and enable to deprive it from the surface of QDs, as a result, the RTP intensity of Mn-doped ZnS QDs/polybrene hybrids was reduced with the increased of heparin concentration. Based on this effect, a selective system was proposed to detect heparin. Under the optimal conditions, the change of RTP intensity was proportional to the heparin concentration from 0.05 to 1.4UmL−1 (about 0.38–10.76μgmL−1) and the limit of detection (LOD) was 0.021UmL−1 (about 0.16μgmL−1). This proposed nanosensor is simple and relatively free of interference from coexisting substances, which can be applied to detect heparin in heparin injection and human serum. In addition, a new pathway was also provided based on the assembly of QDs with other cationic homopolymers for further design of biosensors and detection of biomolecules.

Highly selective manganese-doped zinc sulfide quantum dots based label free phosphorescent sensor for phosphopeptides in presence of zirconium (IV)

We report a room-temperature phosphorescence (RTP) sensor for phosphopeptides based on zirconium (IV)-modulated mercaptopropionic acid (MPA)-capped Mn-doped ZnS quantum dots (QDs). This sensor incorporates the advantages of the well-known Zr4+-phosphopeptide affinity pair and the RTP properties of doped QDs. The RTP of Mn-doped ZnS QDs capped with MPA can be effectively quenched by Zr4+. The high affinity of phosphopeptides to Zr4+ enables the dissociation of the ion from the surface of MPA-capped ZnS QDs, thereby forming a stable complex with phosphopeptides in the solution, and recovering the RTP of the QDs. The Zr4+-induced RTP quenching and subsequent phosphopeptide-induced RTP recovery for MPA-capped ZnS QDs provide a solid basis for the present RTP sensor based on QDs for the detection of phosphopeptides. The detection limit for phosphopeptides is 0.9ngmL−1, the relative standard deviations is 2.5%, and the recovery of urine and serum samples with phosphopeptides addition rangs from 96% to 105% at optimal conditions. The proposed method was successfully applied to biological fluids and obtained satisfactory results.

Melamine-modulated mercaptopropionic acid-capped manganese doped zinc sulfide quantum dots as a room-temperature phosphorescence sensor for detecting clenbuterol in biological fluids

A turn-off room-temperature phosphorescence (RTP) sensor for clenbuterol (CB) based on melamine (MA)-modulated mercaptopropionic acid (MPA)-capped Mn-doped ZnS quantum dots (QDs) was described in this paper. Due to the hydrogen-bonding interaction between CB and MA, introduction of CB into the solution of MPA-capped Mn-doped QDs in the presence of MA could increase the surface defects of the QDs and lead to their reaction aggregation. So that the MA-induced RTP could be enhanced and subsequent CB-induced RTP quenching could be observed. This phenomenon could build a solid base for us to develop a QDs-based turn-off RTP sensor for detecting CB. Under the optimal conditions, the detection limit for CB was 3.2ngmL−1, the relative standard deviations was 2.9% while the recovery of the method was in the range of 97–104%. The coexisting substances which includes 2000-fold excesses of Na+ and K+, 1500-fold excesses of lysine, cysteine, ascorbic acid, uric acid, Vitamin B1, Vitamin B2, Mn2+, Mg2+, Ca2+, Zn2+ and Al3+, 500-fold excesses Cu2+ and Ag+ did not affect the determination of CB. The proposed method was successfully applied to biological fluids with satisfactory results.

Room-temperature phosphorescence sensor based on manganese doped zinc sulfide quantum dots for detection of urea

In this work, a simple scheme was proposed to prepare a urea-sensing system, which was composed of water-soluble Mn-doped ZnS phosphorescent QDs and urease. It allows for effective and quantitative detection of urea. The phosphorescence properties of MPA-capped Mn-doped ZnS QDs were explored to develop an RTP method for facile, rapid, cost-effective and selective detection of urea. This method does not need any deoxidant or other inducers and detects urea in biological fluids without being interfered from autofluorescence or the scattering light of the matrix. The new RTP sensor for urea detection has a detection limit of 0.014mM and two linear ranges from 0 to 10mM and from 10 to 60mM. The precision for 11 replicate detections of 0.1mM urea was 4.7%. The recoveries on spiked urine samples are 95–103%. It was successfully applied to the determination of urine without any complicated sample pretreatment.

Manganese-Doped Zinc Sulfide Quantum Dots for Determination of Bisphenol A by Room Temperature Phosphorescence

Manganese-doped ZnS quantum dots were synthesized through a facile process in aqueous solution using L-cysteine as a surface modifying agent. The quantum dots were characterized by transmission electron microscopy and X-ray diffraction spectroscopy, and had a favorable room-temperature phosphorescence property, with a longer emission time and a narrower emission profile than fluorescence. The phosphorescence was quenched by bisphenol A. Based on these findings, a room temperature phosphorescence quenching method was developed for the sensitive and selective detection of bisphenol A. Under the optimized conditions, the detection limit was 0.2 ng · mL−1, and the relative standard deviation was 1.14% (C = 10 ng · mL−1, n = 11). The proposed method was successfully applied to plastic products with satisfactory results. The recovery of the method was in the range of 96% to 106%.