Capped CdS Quantum Dots Research Articles

Electrochemiluminescent CdS Quantum Dots Biosensor for Cancer Mutation Detection at Different Positions on Linear DNA Analytes.

PCR-based techniques routinely employed for the detection of mutated linear DNA molecules, including circulating tumor DNA (ctDNA), require large nucleotide sections on both sides of the mutation for primer annealing. This means that DNA fragments with a mutation positioned closer to the extremities are unlikely to be detected. Thus, sensors capable of recognizing linear DNA with characteristic mutations closer to the ends would be advantageous over the state-of-the-art approaches. Here, an electrochemiluminescence-resonance energy transfer (ECL-RET) biosensor comprising capped CdS quantum dots and hairpin DNA probes labeled with Au nanoparticles was developed for the detection of epidermal growth factor receptor (EGFR) ctDNA carrying the critical T790M lung cancer mutation. The ECL-RET system detected different DNA molecules including single-stranded 18-nucleotides (nt) and 40-nt as well as double-stranded 100-nt with the single nucleotide polymorphism (SNP) coding for T790M located either in the middle or only 7 nt from one end. For all target DNA, the sensor's limits of detection (LODs) were in the aM range, with excellent selectivity. It was the case of 100-nt target linear ctDNA fragments with LODs of 8.1 and 3.4 aM when the EGFR T790M SNP was either in the middle or at the end, respectively. These results show that ECL-RET systems can sense mutations in DNA fragments that would remain undetected by standard techniques.

Bi-functional aqueous starch capped CdS quantum dots synthesis and their application as sensor of heavy metal-ions as well as photocatalytic dye degradation

CdS quantum dots (QDs) have emerged as the promising nanomaterial for various applications. This study reported bi-functional usage of aqueous starch capped CdS QDs as heavy metal-ion sensor for selective detection of Hg2+ and Cu2+ in aqueous medium as well as sunlight driven photocatalyst for degradation of organic dyes. CdS QDs exhibited colorimetric, spectroscopic, and compositional change with Hg2+ and Cu2+ via cation exchange reaction (CER). The CER of yellow color CdS QDs solution with Hg2+ showed rapid colour change to orange, red and white with composition Cd1-xSHgxS, HgS/CdS, and mixture of HgS and Hg sol, respectively whereas, CER of CdS QDs with Cu2+ resulted in pale brown, brown and greenish brown with composition Cd1-xCuxS, CuxS/CdS and Cu2-xS, respectively. Further, CdS QDs displayed excellent sunlight driven photocatalytic degradation of cationic, anionic and hair dye with good efficiency, reusability, and stability.

Electrochemiluminescence resonance energy transfer system between ruthenium-based nanosheets and CdS quantum dots for detection of chlorogenic acid.

A new strategy is proposedfor ultrasensitive detection of chlorogenic acid (CGA) by fabricating an electrochemiluminescence resonance energy transfer (ECL-RET) sensing platform. Thenovel system designedby introducing ruthenium-based 2D metal-organic framework nanosheets (Ru@Zn-MOF) as ECL acceptor and L-cysteine capped CdS quantum dots (L-CdS QDs) as ECL donor, exhibited good ECL response. The possible mechanism of the modified electrode surface reaction was discussed. Modifying of the electrode surfaceby application of L-CdS QDs directly on ultrathin MOF nanosheets greatly shortened the electron-transfer distance and reduce energy loss, therefore significantly improving the ECL efficiency. The prepared sensor demonstrated good stability and highly selective detection of the target molecule. Under optimal conditions, the constructed sensor for the detection of CGA exhibited a wide linear range from 1.0 × 10-10 to 1.0 × 10-4mol·L-1 and a low detection limit of 3.2 × 10-11mol·L-1 with a correction coefficient of 0.995. Therecovery for spiked samples was calculated to be 94.4-109% and the RSD was 1.07-1.72% in real samples. The obtained sensor is considered to be a promising platform for CGA detection. Electrochemiluminescence resonance energy transfer (ECL-RET) sensing platform is used for the detection for chlorogenic acid.

Synthesis and application of colloidal CdS quantum dots as interface modification material in perovskite solar cells.

In this study, colloidal CdS quantum dots were synthesized, structurally characterized, and their effect on performance of perovskite solar cells was observed by using them as interface modification agent between TiO2/perovskite. Colloidal CdS quantum dots were synthesized based on two-phase method and characterized by X-ray diffraction and Transmission Electron Microscopy techniques. The average particle size of CdS quantum dots have found to be around 5 nm. Oleic acid was used as capping agent during synthesis to lead solubility in organic solvents. Obtained quantum dots are coated on compact TiO2 layer for surface modification. A decrease was observed when oleic acid capped CdS quantum dots were used at interface, while significant improvement was observed when ligand exchange was carried out by pyridine before perovskite layer. Reference solar cells showed 11.6% efficiency, while pyridine capped CdS modified solar cells' efficiency was 13.2%. Besides the improvement in efficiency, reproducibility of solar cells also was increased by using pyridine capped CdS as interface material.

Tailoring the Photoelectrochemical Activity of Hexametaphosphate-Capped CdS Quantum Dots by Ca2+-Triggered Surface Charge Regulation: A New Signaling Strategy for Sensitive Immunoassay.

The development of efficient signaling strategies is highly important for photoelectrochemical (PEC) immunoassay. We report here a new and efficient strategy for sensitive PEC immunoassay by tailoring the electrostatic interaction between the photoactive material and the electron donor. The photoelectric conversion of hexametaphosphate (HMP)-capped CdS quantum dots (QDs) in Na2SO3 solution is significantly boosted after Ca2+ incubation. The negative surface charges on CdS@HMP QDs decrease because of the complexation reaction between HMP and Ca2+, and the electrostatic repulsion between CdS@HMP QDs and electron donor (SO32-) becomes weak accordingly, leading to an improved electron-hole separation efficiency. Inspired by the PEC response of CdS@HMP QDs to Ca2+, a novel "signal-on" PEC immunoassay platform is established by employing CaCO3 nanoparticles as labels. By regulating the surface charge of CdS@HMP QDs with in situ-generated Ca2+ from CaCO3 labels, sensitive detection of the carcinoembryonic antigen (CEA) is achieved. The linear detection range is 0.005-50 ng mL-1 and the detection limit is 1 pg mL-1 for CEA detection. Our work not only provides a facile route to tailor the photoelectric conversion but also lays the foundation for sensitive PEC immunoassay by simply regulating the surface charge of photoactive materials.

Bifunctional Moderator-Powered Ratiometric Electrochemiluminescence Enzymatic Biosensors for Detecting Organophosphorus Pesticides Based on Dual-Signal Combined Nanoprobes.

The bifunctional moderator is urgently needed in the field of ratiometric electrochemiluminescence (ECL) sensing since it can mediate simultaneously two ECL signals to conveniently realize their opposite change trend. This work designed a novel dual-signal combined nanoprobe with carboxyl-functionalized poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(1,4-benzo-{2,1',3}-thiadazole)] nanoparticles (c-PFBT NPs) as the anodic ECL probe and L-cysteine capped CdS quantum dots (L-CdS QDs) as the cathodic ECL probe, which performed a dual-signal output capability without any additional coreactants. More importantly, hydrogen peroxide (H2O2) produced in situ by enzyme-catalyzed reaction was developed as a bifunctional moderator for simultaneously regulating two signals. The dual-signal combined nanoprobe (c-PFBT NPs@CdS QDs) served as the matrix to immobilize acetylcholinesterase (AChE) and choline oxidase for organophosphorus (OPs) analysis. In the absence of OPs, H2O2 was produced by catalyzing the substrate acetylthiocholine (ATCl) with enzymes and it quenched the anodic ECL signal from c-PFBT NPs and simultaneously promoted the cathodic ECL signal from L-CdS QDs. When OPs was present, the activity of AChE was inhibited, the anodic signal would increase, and the cathodic signal would accordingly decrease. The integration of the bifunctional moderator H2O2 and dual-signal combined nanoprobe c-PFBT NPs@CdS QDs not only provides an attractive ECL platform for enzymatic sensing involving the generation or consumption of H2O2 but also paves a new pathway for other ratiometric ECL systems involving enzyme catalytic amplification for detecting antigens, antibodies, DNA, RNA, etc.

Octadecyl amine capped cadmium sulfide quantum dots: morphological studies, electrochemical properties, and its use as photocatalyst for the degradation of methylene blue dyes

We present the structural, optical, electrochemical, and photocatalytic studies of octadecyl amine capped CdS quantum dots (ODA-CdS). TEM micrographs showed CdS quantum dots with particle sizes of 1.9-5.2 nm. The optical bandgaps of the quantum dots are 2.03, 2.06 and 2.01 eV for ODA-CdS1, ODA-CdS2 and ODA-CdS3 respectively, which was less than the bandgap of the bulk CdS (2.42 eV). Photo-electrochemical band gaps of 2.60 V for ODA-CdS1, 2.24 V for ODA-CdS2 and 2.46 V for ODA-CdS3 were obtained from cyclic voltammetry. The photocatalytic degradation efficiency of methylene blue was 62% for ODA-CdS1, 80% for ODA-CdS2, 69% for ODA-CdS3.

Aggregation-Induced Emission Properties of Glutathione and L-Cysteine Capped CdS Quantum Dots and their Application as Zn(II) Probe.

Targeting to obtain better water solubility and stability and less aggregation-caused quenching effects of quantum dots, two kinds of thiol molecules, glutathione and L-cysteine, were firstly united to offer stabilizing ligands for aqueous synthesized CdS quantum dots, which exhibited sensitive aggregation-induced emission properties. Fluorescent intensity of the CdS quantum dots was enhanced about 5 folds by simple solvent exchange from water to 90vol% PEG200. Restriction of intramolecular motions in an aggregate state was probably the main cause of the phenomenon. At the same time, fluorescent intensity of CdS quantum dots in the presence of zinc ions was able to be enhanced about 2.2 folds. Based on the researches, a handy metal enhanced fluorescent probe for detecting zinc ions was established. And the detection limit was 0.58μmol/L. Zinc ions as a bridge among CdS quantum dots to form aggregates limited motions of CdS quantum dots to a certain extent and simultaneously enhanced their fluorescence emission intensities. Meanwhile, activation of surface states of CdS quantum dots also led to emission enhancement. Both of the two factors together contributed to the fluorescence enhancement and ultimately to the sensitivity to zinc ion sample detection.

Glutathione Modified Fluorescent CdS QDs Synthesized Using Environmentally Benign Pathway for Detection of Mercury Ions in Aqueous Phase.

An adept, rapid and novel water-soluble glutathione functionalized CdS quantum dots (GSH@CdS QDs) were fabricated using green pathway for sensing of heavy metal contamination prevalent in industrial wastewater. GSH@CdS QDs were facilely synthesized in an aqueous phase reaction and were effectively characterized using FT-IR, XRD, FESEM, HRTEM and EDX techniques. The distinct fluorescence characteristics of GSH@CdS QDs were explored and the QDs showed selective sensitivity towards mercury ions with a low limit of detection of 0.54nM under optimal conditions. The detailed interaction between GSH@CdS QDs and Hg2+ and the probable fluorescence quenching mechanism were established in this study. In comparison to already reported fluorescent probes, GSH@CdS QDs showed high sensitivity, biocompatibility, long fluorescence stability and convenient removal of mercury ions. Graphical Abstract Facile green route for the fabrication of glutathione capped CdS quantum dots for fluorescence-based detection of toxic Hg2+ ions.

A novel ratiometric molecularly imprinted electrochemiluminescence sensor for sensitive and selective detection of sialic acid based on PEI-CdS quantum dots as anodic coreactant and cathodic luminophore

In this study, a novel potential-resolved ratiometric electrochemiluminescence (ECL) sensor, using Ru(bpy)32+ doped TiO2 nanoparticles (TiO2-Ru(bpy)32+ NPs) with polyethyleneimine (PEI) capped CdS quantum dots (PEI-CdS QDs) as new ECL emitter unit and molecularly imprinted polymer (MIP) as recognition element, was proposed for the first time. Owing to the large specific surface area and porosity of TiO2 NPs plentiful Ru(bpy)32+ was well immobilized on them. The obtained TiO2-Ru(bpy)32+ NPs were able to catalyze the reduction of coreactant H2O2 of PEI-CdS QDs, while the PEI-CdS QDs could serve as the coreactant of TiO2-Ru(bpy)32+ NPs, thus their ECL was promoted by each other. Additionally, graphene oxide (GO) was used to facilitate the electron transfer and sialic acid (SA) imprinted poly(3-aminophenylboronic acid) was electrodeposited on the resulting GO/TiO2-Ru(bpy)32+@PEI-CdS/GCE. When SA concentration increased the anodic ECL signal from TiO2-Ru(bpy)32+ NPs increased, while the cathodic ECL signal from PEI-CdS QDs declined. The sensor exhibited high sensitivity, selectivity and stability. Under the optimized conditions, the linear range was 1.0 nM - 0.1 mM and the detection limit was low to 0.017 nM (S/N = 3). Its good practical feasibility was confirmed by detecting SA in real samples with satisfactory results.

A novel self-enhanced electrochemiluminescence sensor based on PEI-CdS/Au@SiO2@RuDS and molecularly imprinted polymer for the highly sensitive detection of creatinine

In this work, a novel self-enhanced solid state electrochemiluminescence (ECL) platform, based on polyethyleneimine (PEI) capped CdS quantum dots (PEI-CdS QDs) as coreactant and Au@SiO2@Ru(bpy)32+ doped silica (Au@SiO2@RuDS) nanocomposite as ECL emitter, was constructed. The PEI-CdS QDs integrated double coreactant of PEI and CdS QDs, thus significantly promoted the ECL of Au@SiO2@RuDS. Polyaniline hydrogel was introduced to boost the electron transfer and to improve the immobilization of PEI-CdS/Au@SiO2@RuDS. In addition, creatinine imprinted poly(o-aminophenol) film was electrodeposited on the PEI-CdS/Au@SiO2@RuDS surface as recognition element. Thus, the obtained sensor possessed high sensitivity, stability, reproducibility and selectivity for creatinine sensing. The change of ECL intensity and logarithm of creatinine concentration showed a good linear relationship in the range of 0.05 nM to 5 μM, and the detection limit was low to 0.02 nM. The sensor was applied to detect creatinine in human serum and urine samples, and the results were in good agreement with those of commercial enzyme-linked immunosorbent assay kit.

L-Aspartic Acid Capped CdS Quantum Dots as a High Performance Fluorescence Assay for Sliver Ions (I) Detection.

A new high performance fluorescence assay for detection of Ag+ based on CdS quantum dots (QDs) using L-Aspartic acid (L-Asp) as a stabilizer was proposed in this work. The CdS quantum dots conjugation with L-Aspartic acid (L-Asp@CdS QDs) were successfully synthesized via a simple hydrothermal process. The QDs have a fluorescence emission band maximum at 595 nm with a quantum yield of 11%. The obtained CdS QDs exhibit a particle size of 1.63 ± 0.28 nm and look like quantum dot flowers. Basically, the fluorescence intensity of L-Asp@CdS QDs can be enhanced only upon addition of Ag+ and a redshift in the fluorescence spectrum was observed. Under optimum conditions, the fluorescence enhancement of L-Asp@CdS QDs appeared to exhibit a good linear relationship in between 100–7000 nM (R2 = 0.9945) with the Ag+ concentration, with a detection limit of 39 nM. The results indicated that the L-Asp@CdS QDs were well used in detection for Ag+ as fluorescence probe in aqueous solution with high sensitivity and selectivity. Moreover, the sensing system has been applied in detection Ag+ in real water samples. The recovery test results were 98.6%~113%, and relative standard deviation (n = 5) is less than 3.6%, which was satisfactory.

Novel in-situ radiation construction of thioglycollic acid capped CdS quantum dots functionalized g-C3N4 nanohybrids with superior photocatalytic activity under visible light

Abstract: A novel type of thioglycollic acid (TGA) capped CdS QDs functionalized g-C3N4 nanohybrids was prepared successfully by in-situ electron beam radiation at room temperature. When the radiation dose was chosen to be 10 kGy, the concentration of CdCl2 was 0.5 mmol/L and the optimum ratio of TGA to CdCl2 was 3 : 1 at pH = 9.0, the TGA-CdS QDs/g-C3N4 nanohydrids had the highest degradation rate at the modified TGA-CdS QDs content of 3.0 wt % and the removal rate of TGA-CdS QDs/g-C3N4 on the dye of MO was reached 94.7% in less than 20 min. The introduction of TGA-CdS QDs was confirmed successfully by a series of morphologies and structures of characterization and analysis with UV–vis, FL, Inverted-FL, DRS, FTIR, XRD, XPS, FE-SEM and HR-TEM, etc. After the introduction of TGA-CdS QDs into the surfaces of g-C3N4, the recombination of photo-generated electron-hole pairs can be significantly reduced and the photocatalytic activity and photostability can be also improved. It is favorable to enhance the photocatalytic performance for the photo-generated holes are rapidly transferred to the solution and hindered the photo-corrosion of TGA-CdS QDs.

Capped cadmium sulfide quantum dots with a new ionic liquid as a fluorescent probe for sensitive detection of florfenicol in meat samples.

The new ionic liquid capped CdS quantum dots (IL-CdS QDs) as a fluorescent probe was successfully synthesized by a hydrothermal method in a one step process and used for the facile and sensitive determination of florfenicol (FLF) in aqueous media. The new ionic liquid 3-(2-[(5-amino-1,3,4-thiadiazol-2-yl)thio]ethyl)-1-methyl-1H-imidazol-3-ium chloride (IL) was synthesized by introducing 5-amino-1,3,4-thiadiazole-2-thiol as a ligand onto the alkyl chain of the 1-chloroethyl-3-methylimidazolium chloride ILs. This task specific ionic liquid reagent was used for the capping of CdS QDs which played the role of recognition element of FLF. The IL-CdS QDs were characterized by Ultra Violet-Visible absorption -spectroscopy (UV-Vis absorption spectroscopy), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM). Quenching of fluorescence intensity of the IL-CdS QDs was in proportion to the addition of FLF concentration. Under the optimum conditions, the fluorescence intensity ratio of IL-CdS QDs in the presence and absence of FLF versus FLF concentrations gave a linear response according to the Stern-Volmer equation from 0.1 to 20 μg mL-1 (0.3 to 56 μmol L-1) with a limit of detection 0.035 μg mL-1 (0.098 μmol L-1). The developed method was applied to the determination of FLF in fish and chicken meats with satisfactory results. This method revealed some advantages such as high sensitivity, precision and wide linear range to FLF. The proposed method can be utilized for rapid screening the quality of meat products.

Nanocrystalline cellulose decorated quantum dots based tyrosinase biosensor for phenol determination

Novel biosensor architecture based on nanocrystalline cellulose (NCC)/CdS quantum dots (QDs) nanocomposite was developed for phenol determination. This nanocomposite was prepared with slight modification of nanocrystalline cellulose (NCC) with cationic surfactant of cetyltriammonium bromide (CTAB) and further decorated with 3-mercaptopropionic acid (3-MPA) capped CdS QDs. The nanocomposite material was then employed as scaffold for immobilization of tyrosinase enzyme (Tyr). The electrocatalytic response of Tyr/CTAB-NCC/QDs nanocomposite towards phenol was evaluated using differential pulse voltammetry (DPV). The current response obtained is proportional to the concentration of phenol which attributed to the reduction of o-quinone produced at the surface of the modified electrode. Under the optimal conditions, the biosensor exhibits good linearity towards phenol in the concentration range of 5–40 μM (R2 = 0.9904) with sensitivity and limit of detection (LOD) of 0.078 μA/μM and 0.082 μM, respectively.

Oriented assembly of CdS nanocrystals via dynamic surface modification-tailored particle interaction.

The controlled assembly of quantum dots (QDs) remains a challenge due to the lack of in-depth understanding of the roles of ligand dynamics. In this study, tripods, particles, nanorods and nanoflowers of CdS with yellow, red and cyan PL emissions, respectively, were achieved through the coarsening of thioglycolic acid (TGA)-capped CdS QDs with a novel hydroxyl-TGA exchange procedure. Dynamic hydroxyl modification-induced aggregation and coalescence can help to describe the defects and the corresponding photoluminescence characteristics of these nanocrystals. A crystal growth model involving assembly and coalescence was developed to describe the crystal growth and the corresponding PL properties, where hydroxyl-motivated hydrogen-bonding interaction was used to explain the oriented assembly of CdS QDs.

Citric Acid Capped CdS Quantum Dots for Fluorescence Detection of Copper Ions (II) in Aqueous Solution.

Citric acid capped CdS quantum dots (CA-CdS QDs), a new assembled fluorescent probe for copper ions (Cu2+), was synthesized successfully by a simple hydrothermal method. In this work, the fluorescence sensor for the detection of heavy and transition metal (HTM) ions has been extensively studied in aqueous solution. The results of the present study indicate that the obtained CA-CdS QDs could detect Cu2+ with high sensitivity and selectivity. It found that the existence of Cu2+ has a significant fluorescence quenching with a large red shifted (from greenish-yellow to yellowish-orange), but not in the presence of 17 other HTM ions. As a result, Cu2S, the energy level below the CdS conduction band, could be formed at the surface of the CA-CdS QDs and leads to the quenching of fluorescence of CA-CdS QDs. Under optimal conditions, the copper ions detection range using the synthesized fluorescence sensor was 1.0 × 10‒8 M to 5.0 × 10‒5 M and the limit of detection (LOD) is 9.2 × 10‒9 M. Besides, the as-synthesized CA-CdS QDs sensor exhibited good selectivity toward Cu2+ relative to other common metal ions. Thus, the CA-CdS QDs has potential applications for detecting Cu2+ in real water samples.

One-step hydrothermal synthesis of thioglycolic acid capped CdS quantum dots as fluorescence determination of cobalt ion

Highly luminescent CdS quantum dots capped with thioglycolic acid (TGA@CdS QDs) were synthesized from cadmium chloride and thiourea as cadmium and sulfur sources via simple hydrothermal method. The room temperature photoluminescence (RTPL) properties of TGA@CdS QDs were investigated. The results indicate that the polarity of the solvent and the surface trap state resulted in the broadness Stokes shift between the maximum absorption wavelength and the emission wavelength of TGA@CdS QDs. The Co2+ sensing properties of fluorescence determination were investigated using TGA@CdS QDs. The as-synthesized CdS QDs exhibits the excellent selectivity and sensitivity of fluorescence quenching for cobalt ion (Co2+). The limit of detection (LOD) is as low as 0.05 μM which is much lower than maximum limit of cobalt ions in drinking water. The linear response range of Co2+ was from 0.5 to 80 μM. The sensing system revealed the advantages of low detection limit, excellent selectivity, high sensitivity, convenience and low cost. The color change of CdS QDs shows potential applications in the detection of Co2+.

Sensitive fluorescence and chemiluminescence procedures for methamphetamine detection based on CdS quantum dots

Two novel, simple and sensitive fluorescence (FL) and chemiluminescence (CL) procedures were established for methamphetamine (MA) determination. l-Cysteine capped CdS quantum dots (QDs) were synthesized by a simple one-step hydrothermal procedure and characterized by their specific absorption and emission spectra. The structure and morphology of QDs were investigated using X-ray diffraction (XRD) pattern, transmission electron microscopy (TEM) and scanning electron microscope (SEM). It is found that the prepared CdS QDs have a remarkable promoting effect on rhodamine B (RhoB)-cetyltrimethylammonium bromide (CTAB)-KMnO4 CL reaction. Based on this influence, a new efficient CL system was introduced. On the other hand, the FL and CL emission intensities of QDs undergo a remarkable alteration in the presence of low quantities of MA. The optimization of the effective parameters was performed and the high sensitivity was obtained in 0.013molL−1 Tris buffer at pH=6.5 with 0.2mmolL−1 CdS QDs. In this condition, MA had a notable linear quenching effect on the FL emission of QDs which formed the basis of simple FL probe for sensitive determination of MA in the range of 6.7–400ngmL−1. Also, MA can remarkably enhance the intensity of developed CL system. Under the optimized conditions (0.15molL−1 H2SO4, 0.15mmolL−1 RhoB, 0.13mmolL−1 QDs, 0.3mmolL−1 CTAB and 0.4mmolL−1 KMnO4), the improved CL intensity was proportional to the concentration of MA in the range of 0.25–125ngmL−1 with limit of detection (3s) of 0.086ngmL−1, which is over 20 times better than the introduced FL method. The developed FL and CL methods were exploited for accurate determination of MA in human urine samples.

CdS nanocrystals as fluorescent probe for detection of dolasetron mesylate in aqueous solution: Application to biomedical analysis

A simple and straightforward method for the determination of dolasetron mesylate (DM) in aqueous solution was developed based on the fluorescence quenching of 3-Mercaptopropionic acid (MPA) capped CdS quantum dots (QDs). The structure, morphology, and optical properties of synthesized QDs were characterized by using UV-Vis absorption spectroscopy, fluorescence spectroscopy, transmission electron microscopy (TEM) and dynamic light scattering (DLS) measurements. Under the optimum conditions, the MPA-CdS QDs fluorescence probe offered good sensitivity and selectivity for detecting DM. The probe provided a highly specific selectivity and a linear detection of DM in the range of 2–40µg/mL with detection limit (LOD) 1.512µg/mL. The common excipients did not interfere in the proposed method. The fluorescence quenching mechanism of CdS QDs is also discussed. The developed sensor was applied to the quantification of DM in urine and human serum sample with satisfactory results.