Room-temperature Phosphorescence Probe Research Articles

Covalently hybridized carbon dots@mesoporous silica nanobeads as a robust and versatile phosphorescent probe for time-resolved biosensing and bioimaging.

Phosphorescence analyses have attracted broad attention due to their remarkable merits of the elimination of auto-fluorescence and scattering light. However, it remains a great challenge to develop novel materials with uniform size and morphology, stability, long lifetime, and aqueous-phase room temperature phosphorescence (RTP) characteristics. Herein, monodisperse and uniform RTP nanobeads were fabricated by an in situ covalent hybridization of carbon dots (CDs) and dendritic mesoporous silicon nanoparticles (DMSNs) via silane hydrolysis. The formation of Si-O-C and Si-C/N covalent bonds is beneficial for the fixation of vibrations and rotations of the luminescent centers. Specially, the nanopores of DMSNs provide a confined area that can isolate the triplet state of CDs from water and oxygen and thus ensure the occurrence of aqueous-phase RTP with an ultra-long lifetime of 1.195 s (seen by the naked eye up to 9 seconds). Through surface modifying folic acid (FA), CDs@DMSNs can serve as a probe to distinguish different cell lines that feature varying FA receptor expression levels. In addition, taking MCF-7 as the model, highly sensitive and quantitative detection (linear range: 103-106 cells per mL) has been achieved via an RTP probe. Furthermore, their potential applications in cellular and in vivo time-gated phosphorescence imaging have been proposed and demonstrated, respectively. This work would provide a new route to design CD-based RTP composites and promote their further applications in the medical and biological fields.

Alginate capped andmanganese doped ZnS quantum dots as a phosphorescent probe for time-resolved detection of copper(II).

A method is described for the detection of Cu(II). It is based on the use of a room-temperature phosphorescent probe consisting of alginate-cappedand manganese(II)-doped ZnS quantum dots. The carboxy groups at the surface of the probe strongly coordinate Cu(II) to form a complex. As a result, the 4T1-6A1 transition of the Mn(II) ionsin the probe is quenched, and the longdecay time (~2.1 ms in the unquenched state) is accordingly reduced. At excitation/emission wavelengths of 316/590 nm and a delay time of 0.1 ms, the probe shows a linear response in the 0.01 to 12 μM Cu(II) concentration range. The detection limit is 6.0 nM and the RSD is 3.2% (for n = 5). Graphical Abstract A two-step procedure is describedto synthesize alginate capped manganese doped ZnS QDs. These coordinate with Cu(II) to form an absorbent complex and can be used as a phosphorescent probe for time-resolved detection of Cu(II).

Correction to: Rapid Detection of Acrylamide in Food Using Mn-Doped ZnS Quantum Dots as a Room Temperature Phosphorescent Probe

The original version of this article unfortunately contained mistakes. The sentence “ACR was determined in all samples in the range of 24.3 to 453.2 g kg−1.” should read “ACR was determined in all samples in the range of 24.3 to 453.2 μg kg−1.” In Table 2 header, it should be “Sample value (μg kg−1)”.

Rapid Detection of Acrylamide in Food Using Mn-Doped ZnS Quantum Dots as a Room Temperature Phosphorescent Probe

Acrylamide (ACR) is a potential carcinogen and is found in thermally processed foods such as potato chips, biscuits, baby foods, coffee, etc. In this paper, l-cysteine-capped Mn-doped ZnS quantum dots (QDs) as phosphorescent probes were used for the determination of ACR. This method based on quenching of the phosphorescence intensity of the QDs with the interaction of ACR. Room temperature phosphorescence (RTP) intensity of QDs was quenched rapidly upon the addition of the quencher. The quenching mechanism of Mn-doped ZnS QDs by ACR was dynamic and the quenching constant was found as 3 × 104 M−1. A linear response was observed from 2 to 20 μg mL−1 of ACR with a limit of detection of 0.56 μg mL−1. ACR was determined in all samples in the range of 24.3 to 453.2 g kg−1. The results showed that the proposed method is sensitive, selective, fast, and does not require a derivatization step.

Surface molecular imprinted polymers based on Mn-doped ZnS quantum dots by atom transfer radical polymerization for a room-temperature phosphorescence probe of bifenthrin

Based on the room-temperature phosphorescence (RTP) peculiarity of Mn-doped ZnS quantum dots (QDs), a bifenthrin sensor was fabricated by coupling molecular imprinted polymers (MIPs) on the surface of silane modified QDs via atom transfer radical polymerization (ATRP).

Room-temperature phosphorescence probe based on Mn-doped ZnS quantum dots for the sensitive and selective detection of selenite

Selenite was selectively and sensitively detected based on the room-temperature phosphorescence quenching of Mn–ZnS QDs caused by HSe− from the reaction of selenite and glutathione.

Mn-doped ZnS quantum dots as a room-temperature phosphorescent probe for analysis of glutamic acid in foodstuffs

L-cysteine-capped Mn-doped ZnS quantum dots (QDs) were used for the determination of glutamic acid in foodstuffs. This method is based on measurement of the quenching of the phosphorescence intensity of the QDs after interacting with glutamic acid. A linear response was observed from 50 to 500 ng mL$^{-1}$ glutamic acid with a limit of detection of 6.79 ng mL$^{-1}$. Room temperature phosphorescence (RTP) intensity of the QDs was quenched rapidly upon the addition of the quencher and the reaction reached equilibrium within 2 min. The quenching mechanism of phosphorescence of Mn-doped ZnS QDs by glutamic acid is dynamic and the quenching constant was found as 1.9 $\times $ 10$^{5}$ M$^{-1}$. The developed method has some advantages such as freeness of interference from autofluorescence or common cations. The results showed that the proposed method is sensitive, selective, and fast, and does not require a derivatization step.

Highly-controllable imprinted polymer nanoshell at the surface of silica nanoparticles based room-temperature phosphorescence probe for detection of 2,4-dichlorophenol

This paper reports a facile and general method for preparing an imprinted polymer thin shell with Mn-doped ZnS quantum dots (QDs) at the surface of silica nanoparticles by stepwise precipitation polymerization to form the highly-controllable core–shell nanoparticles (MIPs@SiO2–ZnS:Mn QDs) and sensitively recognize the target 2,4-dichlorophenol (2,4-DCP). Acrylamide (AM) and ethyl glycol dimethacrylate (EGDMA) were used as the functional monomer and the cross-linker, respectively. The MIPs@SiO2–ZnS:Mn QDs had a controllable shell thickness and a high density of effective recognition sites, and the thickness of uniform core–shell 2,4-DCP-imprinted nanoparticles was controlled by the total amounts of monomers. The MIPs@SiO2–ZnS:Mn QDs with a shell thickness of 45nm exhibited the largest quenching efficiency to 2,4-DCP by using the spectrofluorometer. After the experimental conditions were optimized, a linear relationship was obtained covering the linear range of 1.0–84μmolL−1 with a correlation coefficient of 0.9981 and the detection limit (3σ/k) was 0.15μmolL−1. The feasibility of the developed method was successfully evaluated through the determination of 2,4-DCP in real samples. This study provides a general strategy to fabricate highly-controllable core–shell imprinted polymer-contained QDs with highly selective recognition ability.

Mn-Doped ZnS Quantum Dot Imbedded Two-Fragment Imprinting Silica for Enhanced Room Temperature Phosphorescence Probing of Domoic Acid

A novel strategy was presented to construct the enhanced molecularly imprinted polymer (MIP)-based room temperature phosphorescence (RTP) probe by combining the RTP of Mn-doped ZnS quantum dots (Mn-ZnS QDs) and two-fragment imprinting. Two fragments or structurally similar parts of the target analytes were used as the dummy templates. Polyethyleneimine capped Mn-ZnS (PEI-Mn-ZnS) QDs, offering the binding sites to interact with the carboxyl groups of templates, were imbedded into MIPs by the hydrolysis of tetraethoxysilane. The rebinding of the target analytes to their fragments' cavities (recognition sites) modulated the selective aggregation of Mn-ZnS QDs in QDs-MIPs and resulted in the RTP enhancement. This new method was suitable for the selective enhanced RTP detection of nonphosphorescent analytes without any derivatization and inducers. The proposed methodology was applied to construct the high selective enhanced MIP-based RTP probe for domoic acid (DA) detection. The RTP enhancement of two-fragment imprinting silica was about 2 times of one-fragment imprinting silica and 4 times of the nonimprinting silica. The two-fragment imprinting silica exhibited the linear RTP enhancement to DA in the range of 0.25-3.5 μM in buffer and 0.25-1.5 μM in shellfish sample. The precision for 11 replicate detections of 1.25 μM DA was 0.65% (RSD), and the limit of detection was 67 nM in buffer and 2.0 μg g(-1) wet weight (w/w) in shellfish sample.

Enhancement of Palladium‐Porphyrin Room Temperature Phosphorescence by Alkaline Earth Metal in Deoxycholate Aggregates Solution

Room temperature phosphorescence (RTP) of three palladium (Pd)-phorphyrins in air-saturated solution of sodium deoxycholate (NaDC) aggregates was measured. RTP of Pd-meso-tetrakis (4-carboxyphenyl) porphyrin (Pd-TCPP) was obviously enhanced in NaDC-aggregates mediated by alkaline earth metal (AEM). Under the same experimental conditions, Ca(2+), Ba(2+) and Mg(2+) induced 200, 90 and 24 times greater enhancement in RTP of Pd-TCPP, respectively. It is ascribed to form the complex of NaDC-aggregate/AEM/Pd-TCPP in the system. The positively charged AEM has a strong capability of co-ordination with negatively charged carboxyl groups of NaDC and Pd-TCPP. The phosphor Pd-TCPP is confined in rigid NaDC-aggregates/AEM system by the coordination which decreases the probability of collision of phosphor with quenchers such as dissolved oxygen molecules and prolongs the lifetime of the phosphor on the triplet state. Long excited-state lifetimes resulted in great enhancement of Pd-TCPP phosphorescence. Observations by optical microscope showed that specific fan-like structures of NaDC were formed under the influence of AEM. Surface tension measurements supported a close interaction between Ca(2+) ions and anion aggregates of NaDC with 1:1 stoichiometric ratio. Due to its outstanding RTP behavior in NaDC-aggregates induced by Ca(2+), Pd-TCPP was used as a RTP probe to detect bovine serum albumin (BSA). A broad linear range from 1.0 × 10(-9) to 9.0 × 10(-7) g mL(-1) was obtained. Detection limit is 2.6 × 10(-11) g mL(-1), the relative standard deviation (n = 6) is 2.3% for 2.0 × 10(-9) g mL(-1) BSA.

Ascorbic Acid Induced Enhancement of Room Temperature Phosphorescence of Sodium Tripolyphosphate‐Capped Mn‐Doped ZnS Quantum Dots: Mechanism and Bioprobe Applications

Although quantum dot (QD)-based room temperature phosphorescence (RTP) probes are promising for practical applications in complex matrixes such as environmental, food and biological samples, current QD-based-RTP probes are not only quite limited but also exclusively based on the RTP quenching mechanism. Here we report an ascorbic acid (AA) induced phosphorescence enhancement of sodium tripolyphosphate-capped Mn-doped ZnS QDs, and its application for turn-on RTP detection. The chelating ability allows AA to extract the Mn and Zn from the surface of the QDs and to generate more holes which are subsequently trapped by Mn(2+), while the reducing property permits AA to reduce Mn(3+) to Mn(2+) in the excited state, thereby enhancing the excitation and orange emission of the QDs. The enhanced RTP intensity of the QDs increases linearly with the concentration of AA in the range of 0.05-0.8 μM. Thus, a QD-based RTP probe for AA is developed. The proposed QD-based turn-on RTP probe avoids tedious sample pretreatment, and offers good sensitivity and selectivity for AA in the presence of the main relevant metal ions and other molecules in biological fluids. The limit of detection (3s) of the developed method is 9 nM AA, and the relative standard deviation is 4.8 % for 11 replicate detections of 0.1 μM AA. The developed method is successfully applied to the analysis of real samples of human urine and plasma for AA with quantitative recoveries from 96 to 105 %.

Determination of Trace Deoxyribonucleic Acid Based on a Room Temperature Phosphorescent Probe of Alizarin Red-piperidine Self-ordered Ring

This research combined the self-ordered ring (SOR) technology with solid substrate-room temperature phosphorimetry (SS-RTP) and developed a new (ARS)n-P-SOR (ARS is alizarin red S, (ARS)n refers to multiple ARS molecules, P is piperidine). (ARS)n-P-SOR could increase the number of ARS molecules in the biological target, which could further improve the sensitivity of SS-RTP. Thus, a new SS-RTP for the determination of trace deoxyribonucleic acid (DNA) was established using (ARS)n-P-SOR as a phosphorescent probe. This method was successfully applied to the determination of DNA in nectar. Meanwhile, the mechanism of determining trace DNA by (ARS)n-P-SOR was discussed.

An extrinsic room temperature phosphorescent probe. Remarkable shielding of benzophenone triplet at the active site of chymotrypsin

Benzophenone can be used as an extrinsic triplet state probe, as its phosphorescence, a broad band centered at 445 nm, is readily observable in aqueous solution at room temperature. When bound covalently as an acyl enzyme at the active site of chymotrypsin, the benzophenone probe produces phosphorescence which is unusually resistant to quenching by O 2, trans -cinnamic acid, and H 3O +. Sodium 2-naphthalenesulfonate quenches the phosphorescence, probably indirectly. The quenching data indicate that the local protein structure at the enzyme active site provides a rigid and protective substrate environment, which is not penetrated by even the smallest triplet quenchers.