MPA-capped Mn-doped ZnS Research Articles

Mercaptopropionic acid-capped Mn-doped ZnS quantum dots and Pb2+ as sensing system for rapid and sensitive room-temperature phosphorescence detection of sulfide in water

As a kind of serious concern environmental toxic pollutants, sulfide is widely used in various industrial processes, and generated from the process of biological metabolism. However, the sensitive, rapid and effective detection of sulfide still remains challenge. In this paper, a simple and rapid room-temperature phosphorescence (RTP) method for the detection of sulfide with a high selectivity and sensitivity was proposed by using mercaptopropionic acid (MPA)-capped Mn-doped ZnS quantum dots (QDs) and Pb2+ as a sensing system. Highly water-soluble MPA-capped Mn-doped ZnS QDs with phosphorescence emission property were successfully synthesized by microwave-assisted hydrothermal synthesis method. We discovered that the as-prepared QDs displayed effectively phosphorescence quenching to Pb2+ in pH 11.5 borax-NaOH buffer solution, then demonstrated remarkable phosphorescence recovery after the addition of sulfide to the QDs-Pb2+ system. Therefore, based on the phosphorescence "off-on" behavior of MPA-capped Mn-doped ZnS QDs, a simple, sensitive and selective phosphorescence method for rapid detection of sulfide was successfully developed. The quenching and recovery of the phosphorescence of MPA-capped Mn-doped ZnS QDs have been studied in detail. Under the optimized conditions, the recovered degree of RTP intensity had a very good linear relationship with sulfide concentration in the range of 2 × 10−7–80 × 10−7 mol L−1 with a correlation coefficient of 0.9982, and a lower detection limit of 6.89 × 10−8 mol L−1. The relative standard deviations for eleven times repeated detections of 5 × 10−6 and 8 × 10−6 mol L−1 sulfide were 3.24% and 4.50%, respectively. The proposed method could effectively avoid the interferences of common anions, fluorescence substances and scattering light. Furthermore, it was successfully applied to detect sulfide in real water samples with satisfactory results, and the recoveries were in the range from 94.2% to 107.1%. This work will provide the basis of method for the development of fast and on-line monitoring sensors of small molecule pollutions in water.

Phosphorescence detection of 2-mercaptobenzothiazole in environmental water samples by Mn-doped ZnS quantum dots

A room-temperature phosphorescence sensor was constructed based on MPA-capped Mn-doped ZnS QDs for the detection of MBT in water samples.

A convenient “turn on-off” phosphorescent nanosensor for detection of biotin based on quantum dots/CTAB

A switchable room-temperature phosphorescence(RTP) nanosensor based on an MPA-capped Mn-doped ZnS QDs/CTAB composite system(MPA=3-mercaptopropionic acid; CTAB=cetyltrimethyl ammonium bromide; QDs=quantum dots) was established for the detection of biotin. The phosphorescence intensity of QDs/CTAB could be regularly quenched with the increase of biotin. Under optimal conditions, this method yielded two linear ranges of 2―20 μg/L and 20―140 μg/L with respective correlation coefficients of 0.993 and 0.990, as well as a detection limit of 0.93 μg/L. Therefore, the analytical potential of the proposed nanosensor was evaluated by detecting biotin in urine and biotin tablets. This approach yielded satisfactory results because of the effective elimination of background fluorescence and light scattering from the sample matrix. This approach provides a practical method for biotin detection.

A sensitive phosphorescence method based on MPA-capped Mn-doped ZnS quantum dots for the detection of diprophyllin

The mechanism of the phosphorescence quenching process of Mn-doped ZnS QDs by DPP.

Room-Temperature Phosphorescence Turn-on Detection of DNA Based on Riboflavin-Modulated Manganese Doped Zinc Sulfide Quantum Dots.

A sensitive phosphorescent sensor based on riboflavin (RF)-modulated mercaptopropionic acid (MPA)-capped Mn-doped ZnS quantum dots (QDs) was developed and utilized as room-temperature phosphorescence (RTP) sensor for DNA detection. The RTP of the MPA-capped Mn-doped ZnS QDs was stored via photoinduced electron transfer by RF, and formed an electrochemically nonactive QDs/RF nanohybrids through electrostatic attraction. In the presence of DNA, RF could bind with DNA, which has a double helical structure, via electrostatic interaction and intercalation. RF can be removed from the surface of the QDs, thus releasing the RTP of the QDs. On the basis of this principle, an RTP sensor for DNA detection was developed. Under optimal conditions, the detection limit for DNA was 15μgmL(-1), the relative standard deviation was 1.9%, and the method recovery ranged from 97% to 103%. The proposed method was applied to biological fluids, in which satisfactory results were obtained.

Detection of glucose with room-temperature phosphorescent quantum dots without conjugation

A superior method was constructed for rapid and sensitive detection of glucose by utilization of room-temperature phosphorescent (RTP) quantum dots (QDs) without sophisticated conjugation between QDs and glucose oxidase (GOD) nor complex pretreatments, such as oxygen removal, and free from the interference of autofluorescence and scattering light, which can be used to detect glucose in biological fluids. This kind of principle is based on the quenching effect of H2O2 on MPA-capped Mn-doped ZnS QDs (MPA: 3-mercaptopropionic acid), and such quenching process is called as Photoinduced Electron Transfer (PIET). The GOD decomposed glucose and released H2O2, then H2O2 obtained electron from MPA-capped Mn-doped ZnS QDs in order to form H2O and O2, and finally quenched RTP of MPA-capped Mn-doped ZnS QDs via PIET, therefore, a new method for glucose detection was built on this basis. However, this biosensor has a detection limit of 0.0029mM and two linear ranges from 0.005 to 0.1mM and from 0.1 to 0.4mM.

Detection of quercetin based on Al3+-amplified phosphorescence signals of manganese-doped ZnS quantum dots

A simple phosphorescence method is proposed for quercetin detection based on Al3+-amplified room-temperature phosphorescence (RTP) signals of 3-mercaptopropionic acid (MPA)-capped Mn-doped ZnS quantum dots (QDs). The sensor was established based on some properties as follows. Al3+ can interact with carboxyl groups on the surface of MPA-capped Mn-doped ZnS QDs via chelation, which will lead to the aggregation of QDs and amplification of RTP signals, After the addition of quercetin, it can form more stable complex with Al3+ in alkaline aqueous solution and dissociate Al3+ from the surface of Mn-doped ZnS QDs, which will result in significant recovery of RTP intensity of the MPA-capped Mn-doped ZnS–Al3+ system. Under the optimized conditions, the change of RTP intensity was proportional to the concentration of quercetin in the range from 0.1 to 6.0 mg L−1, with a high correlation coefficient of 0.996 and a detection limit of 0.047 mg L−1. The proposed method is potentially suitable for detection of quercetin in real samples without complicated pretreatment.

Facile and sensitive detection of protamine by enhanced room-temperature phosphorescence of Mn-doped ZnS quantum dots

Quantum dot (QD) nanohybrids provide an effective route to explore the new properties of materials and are increasingly used as highly valuable sensitive (bio) chemical probes. Interestingly, the room-temperature phosphorescence (RTP) of 3-mercaptopropionic acid (MPA)-capped Mn-doped ZnS QDs could be remarkably enhanced by the addition of protamine. Based on the above finding, a simple, sensitive, and selective method for rapid detection of protamine was successfully designed. With this method, protamine as a cationic peptide interacts electrostatically with MPA-capped Mn-doped ZnS QDs to form MPA-capped Mn-doped ZnS QD/protamine complexes, which leads to the aggregation of QDs and enhances the RTP intensity. Under the optimized conditions, the RTP intensity change was linearly proportional to the concentration of protamine in the range 0.2–3.0μgml−1, and the limit of detection was 0.14μgml−1. The proposed method was successfully applied to detect protamine in protamine sulfate injection and human serum samples with satisfactory results, and the recovery ranged from 96.5 to 105.6%.

Phosphorescent quantum dots/doxorubicin nanohybrids based on photoinduced electron transfer for detection of DNA

MPA-capped Mn-doped ZnS QDs/DXR nanohybrids (MPA: 3-mercaptopropionic acid; QDs: quantum dots; DXR: cetyltrimethyl ammonium bromide) were constructed via photoinduced electron transfer (PIET) and then used as a room-temperature phosphorescence (RTP) probe for detection of DNA. DXR as a quencher will quench the RTP of Mn-doped ZnS QDs via PIET, thereby forming Mn-doped ZnS QDs/DXR nanohybrids and storing RTP. With the addition of DNA, it will be inserted into DXR and thus DXR will be competitively desorbed from the surface of Mn-doped ZnS QDs, thereby releasing the RTP of Mn-doped ZnS QDs. Based on this, a new method for DNA detection was built. The sensor for DNA has a detection limit of 0.039mgL−1 and a linear range from 0.1 to 14mgL−1. The present QDs-based RTP method does not need deoxidants or other inducers as required by conventional RTP detection methods, and avoids interference from autofluorescence and the scattering light of the matrix that are encountered in spectrofluorometry. Therefore, this method can be used to detect the DNA content in body fluid.

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.

Self-assembly of manganese doped zinc sulfide quantum dots/CTAB nanohybrids for detection of rutin

Quantum dots (QDs) nanohybrids are an effective route to obtain new property of materials, and are very significant for developing specific materials and improving the performance of existing QDs materials. The objectives of this work are to prepare MPA-capped Mn-doped ZnS QDs/CTAB nanohybrids (MPA: 3-mercaptopropionic acid; CTAB: cetyltrimethyl ammonium bromide) through electrostatic self-assembly, to investigate the formation mechanism and the Room-Temperature Phosphorescenee (RTP) changes, and to explore the possibility of their application in detection of rutin. As a result, MPA-capped Mn-doped ZnS QDs/CTAB nanohybrids greatly improve the rutin detection ability of QDs and provide an important method for developing more convenient and effective rutin detection sensor. The sensor for rutin gave a detection limit of 0.037mgL−1 and two linear ranges from 0.05 to 0.5mgL−1 and from 0.5 to 5mgL−1, and thus can be expanded to selective detection of other substances. Since the present QDs-based RTP method does not need deoxidants or other inducers as conventional RTP detection methods, and avoids interference from autofluorescence and the scattering light of the matrix that are encountered in spectrofluorometry, this method can be used to detect the content of rutin in body fluid.