Doped ZnS Quantum Dots Research Articles

Structural, morphological, electrochemical and optical properties ZnS quantum dots: Influence of La3+ ions

The La-doped ZnS quantum dots were prepared by the facile co-precipitation technique. XRD patterns revealed the cubic structure of the ZnS crystal lattice. We measure the size of the synthesized nanoparticles at approximately 2 nm. Sulfur vacancies on the structure’s surface produce some defects. The HR-TEM and FE-SEM results also confirm the size, morphology, and other structural entities. The EDS and FTIR results confirmed the composition of the samples. We tested the electrochemical behaviors of the samples, and found that La 4 at% doped-ZnS offered a high specific capacitance. The enhancement of optical absorbance was observed by the UV–vis studies. A red shift was received in band gap due to incorporation of La ions. We observe high optical transmittance for La 2 at.% doped-ZnS quantum dots. PL emission results showed a weak emission in the UV region, and some defect-related emissions in the visible region.

A versatile internal filtration effect-based ratiometric probe for fluorescence and naked eye sensing of 2,2′,4,4′,6,6′-hexanitrostilbene

2,2′,4,4′,6,6′-hexanitrostilbene (HNS) detection is an essential issue in homeland security screening and environment monitoring. Herein, Mn doped ZnS quantum dots (QDs), ethanolamine (EA) and dansyl hydrazine (DNSH) were proposed as ratiometric probes (DNQDs) for fluorescent (FL), visual FL (VFL), and naked-eye-based visual (NEBV) detection of HNS on surfaces and in water. The amino-HNS complex was formed due to the reaction between HNS and EA after adding HNS into DNQDs. The complex could quench the FL emission of the QDs and DNSH with different rates because of the internal filtration effect. HNS sensing was acquired by comparing the ratio change between their FL intensities. Meanwhile, DNQDs could be used for NEBV sensing of HNS by recognizing the orange-red colored complex. DNQDs demonstrated a good sensitivity: the lowest detectable concentrations/amounts of FL, VFL, and NEBV methods for HNS in water were 0.025, 2.5, and 5 mg/L, and those of VFL and NEBV methods for HNS on surfaces were 0.64 and 1.59 μg/mm2, respectively. Finally, DNQDs were successfully utilized for HNS detection on palm and travel bag surfaces as well as in environmental water. DNQDs-based approaches might be a promising potential for HNS analysis owing to the high sensitivity and versatility.

Structural, bandgap tailoring, photoluminescence and electrochemical characteristics of Sm3+-doped ZnS quantum dots prepared in Ar-atmosphere

Sm3+-doped ZnS quantum dots were prepared by a cost-effective, simple co-precipitation technique under an argon atmosphere. The prepared Sm3+-doped QDs exhibited a cubic structure with an average particle size of ∼ 2 nm, as confirmed through X-ray diffraction and high-resolution transmission electron microscopic investigations. The crystallite was reduced and strain produced due to the larger ionic radius of Sm3+ ions. The Sm (at. 2 %)-doped ZnS exhibited a blue shift, and the optical transmittance was enhanced. A highly intense red emission was obtained in photoluminescence investigations, and this is due to the transfer of photons from 4G5/2 → 6H11/2 for f-f transitions of the Sm3+ in the 4f5 configuration. The obtained photoluminescence emissions lead to red phosphor applications. The cyclic voltammogram analysis showed that adding Sm to ZnS QDs made their specific capacitance value higher and it found potential applications in supercapacitors.

Eu3+ singly-doped and Eu3+/Sm3+ co-doped ZnS quantum dots: structure, optical properties and energy transfer.

In this study, Eu3+ ion singly doped and Eu3+/Sm3+ ions co-doped ZnS semiconductor quantum dots (QDs) were successfully synthesized using a wet chemical method in 1-octadecene (ODE) solvent. The successful doping of Sm3+ and Eu3+ ions into the ZnS host lattice and the composition and valence of the elements present in the sample were confirmed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Structural and morphological studies revealed the presence of Eu3+-doped ZnS and Eu3+/Sm3+ co-doped ZnS QDs of about 3-4 nm size with a zinc blende structure. The Judd-Ofelt (J-O) intensity parameters of Eu3+-doped ZnS QDs were determined from their fluorescence spectra. The optical properties of Eu3+/Sm3+ co-doped ZnS QDs were studied by changing the Eu3+ ion concentration and fixing the Sm3+ ion concentration. The photoluminescence (PL) spectra of Eu3+/Sm3+ co-doped ZnS QDs were obtained at an excitation wavelength of 403 nm (6H5/2 → 6P3/2 transition of Sm3+ ions) in the 525-725 nm range. The effective energy transfer (ET) process from Sm3+ to Eu3+ ions was confirmed and explained in detail using the Reisfeld approximation and the Inokuti-Hirayama model. The CIE color coordinates of the Eu3+/Sm3+ co-doped ZnS QDs were obtained using PL spectral data. Eu3+/Sm3+ co-doped ZnS QDs exhibited a long lifetime and emitted warm red light. These interesting properties give Eu3+/Sm3+ co-doped ZnS QDs great potential for applications in photovoltaics, photocatalysis, and biomarkers.

Fluorescent and visual sensing of sodium dodecylbenzene sulfonate with an aminosilane self-condensation promoting and electrostatic attraction effect-based ratiometric probe

BackgroundIncreasing attention has been paid to sodium dodecylbenzene sulfonate (SDBS) detection because it could cause damage to human body and environmental water. For example, SDBS must not be detected on tableware surface according to national standard of China (GB 14934-2016). However, there is no report heretofore addressing SDBS sensing on surfaces. More importantly, the interferents often affect the sensing performance of analytical approaches. Hence, there is an urgent need to establish a method with good anti-interference ability for SDBS detection both on tableware surfaces and in water. ResultsInspired by a finding that SDBS could cause the generation of white turbidity in (3-aminopropyl)trimethoxysilane (APTMS, an aminosilane) aqueous solution, APTMS modified Mn doped ZnS quantum dots (QDs) and fluorescent (FL) whitening agent (FWA) were constructed as a ratiometric probe for FL and visual sensing of SDBS. The modified QDs aggregated and settled in presence of SDBS, which was likely to be connected to the stimulatory effect of SDBS on the APTMS self-condensation and the electrostatic attraction. The FL emission from the QDs at 605 nm then decreased dramatically, whereas that at 425 nm was virtually constant owing to FWA. SDBS sensing could be achieved by calculating the ratio change of their FL intensities. The detection limits of FL and visual methods were found to be 0.011 and 10 μg/L, respectively, making it one of the most sensitive approaches in literature. Finally, it was successfully utilized for SDBS detection on tableware surfaces and in water. SignificanceHerein, the specific interaction between SDBS and APTMS was reported and the reaction mechanisms were explored for the first time. The proposed probe based on the effect described above provided a promising potential for SDBS analysis owing to high sensitivity, selectivity, anti-interference ability, and stability (in 20 days).

Optical properties, Judd-Ofelt analysis and energy transfer processes of Eu3+ doped ZnS quantum dots

Quantum dots (QDs) of ZnS doped with different Eu3+ ion concentrations were synthesized using a chemical method. The X-ray diffraction (XRD) pattern showed that the prepared QDs were crystallized in the Zincblende phase and their size was estimated to be approximately 3 nm. The XRD pattern and XPS spectrum analysis showed that Eu3+ ions replaced Zn2+ ions in the crystal lattice. For the first time, the optical properties of Eu3+ doped ZnS QDs were studied using photoluminescence excitation (PLE), photoluminescence (PL) spectra, and Judd-Ofelt (J-O) theory. Ωλ (λ = 2, 4, 6) parameters were calculated from the PLE spectra of the samples. The luminescence quantum efficiency and properties of the ligand field of the material were calculated and compared with those of other lattice hosts. The energy transfer (ET) processes from the ZnS host to Eu3+ ion and between Eu3+ ions were also discussed in detail. The ET process from the ZnS host to the Eu3+ ion occurred through the exchange interaction. The dominant interaction between Eu3+ ions in the ET process is the dipole-dipole mechanism, which is determined by fitting the decay curve of the 5D0 level to the Inokuti-Hirayama model.

“Turn-on” fluorescence sensing of cardiac troponin I based on MnO2 nanosheet quenched mercaptopropionic acid capped Mn2+ doped zinc sulphide quantum dots

Acute Myocardial Infarction (AMI) is the persisting serious threat among all cardiovascular diseases due to its highest mortality rates. Clinicians resort to biomarker levels pertinent to AMI in triaging patients. Among the several cardiac biomarkers, by virtue of the specificity and sensitivity, cardiac troponin I (cTnI) was recognized as the gold standard for AMI diagnosis. Immunosensors that have been developed for cTnI detection are limited by multistep process and long diagnostic time which makes them unadaptable in primary healthcare centres. Recently, Fluorescence Resonance Energy Transfer (FRET) based immunosensors have found wide applicability in biomolecule detection. Among the evolving nanomaterials, Quantum dots (QDs) have been emerged as attractive donors in FRET based sensors for biomolecules. In the present work, we report a simple and sensitive fluorescence immunosensor for cTnI detection using Mercaptopropionic acid (MPA) capped Mn2+ doped ZnS QDs and MnO2 nanosheet as the FRET couple. For the specific detection of cTnI antigen, we have coupled cTnI antibody on the surface of MPA capped Mn2+ doped ZnS QDs. cTnI can be detected linearly with a low Limit of Detection (LoD) of 0.05 ng/mL. Furthermore, the selectivity of the developed probe has also been evaluated in the presence of other potential interferants and other cardiac biomarkers. In real serum samples, good recovery percentage was obtained proving that the probe is adaptable for Point of care detection of cTnI.

An experimental and theoretical study on photoluminescence of Ce3+-doped ZnS quantum dots and their application in Aspergillus oryzae

ZnS and ZnS:3.125%Ce3+ (ZSC) quantum dots (QDs) were synthesized by a low-temperature solid-phase method. The crystal structure, photoluminescence (PL) properties of ZSC QDs, and their effects on the growth and kojic acid production of Aspergillus oryzae (A. oryzae) were investigated. It is found that both QDs have a cubic blend structure with the average particle size ranging of 2.75–6.14 nm. Ce3+ doping not only increases the band gap of ZnS QDs from 3.43 to 3.48 eV, but also increases the PL intensity by about 2.23 times, which is due to the fact that the electron carrier concentration is improved, and then the rate of radiative recombination is increased. The integral emission intensity, biomass, extracellular proteins yield, and kojic acid production of A. oryzae cultured with ZSC (ZnS) QDs are about 4.31 (3.23), 1.61 (1.20), 1.12 (1.09), and 2.99 (1.68) times higher than that of medium without QDs, respectively.

Luminescent Manganese/Europium doped ZnS quantum dots: Tunable emission and their application as fluorescent sensor

Manganese and europium doped zinc sulphide (Mn2+/Eu3+@ZnS) quantum dots (QDs) were prepared via direct aqueous route in order to broaden tunable emission. We report a new strategy featuring enhanced photoluminescence through Mn2+/Eu3+@ZnS QDs leading to an intense orange-red emission and thus remarkably enhancing PL QY up to 41.35%. The X-ray diffraction (XRD) and Transmission Electron Microscope (TEM) studies revealed the cubic crystalline structure with average crystalline sizes in the range of 1.5–2.5 nm. The Mn2+/Eu3+@ ZnS QDs was applied as an exceptional chemical sensor for Cu2+ via quenching mechanism due to competitive coordination between QDs and Cu2+ with the limit of detection (LOD) of 0.036 μM. Furthermore, the proposed approach is capable of detecting Cu2+ in water samples with satisfactory recoveries highlighting viability and prospective applications of the sensing platform. We finally demonstrate from CIE Chromaticity diagram that doped QDs show meliorated colorimetric properties which render this new class of QDs a promising prospect to be employed in white LEDs.

Fluorescent sensor based on thiourea capped Mn doped ZnS quantum dots for the sensing of Cu2+ ions in water

In the present study the utilization of a simple, rapid, and highly effective “turn-off” fluorescent sensor based on thiourea capped manganese doped zinc sulphide quantum dots for the detection of Cu2+ ions in water is described for the first time. The quantum dots are prepared by a simple and facile chemical precipitation method. The developed quantum dots are characterized by UV–vis., FT-IR, photoluminescence, XRD, and TEM techniques. The doping by manganese is confirmed by a peak at 598 nm in the PL spectrum. The sensor exhibit high sensitivity and selectivity towards copper ion at pH 9 with a limit of detection of 20.75 nM. The obtained results are also reasonable in real sample analysis.

Phosphorescence aptasensing system for sulfadimethoxine with petal-like MoS2 nanosheets for signal amplification

The fast and accurate detection of residual veterinary antibiotics in food has great significance for the ecological balance and human health. This study presents a room temperature phosphorescence aptasensing system for sulfadimethoxine (SDM) detection with sulfadimethoxine-aptamer (SDM-APT) modified manganese doped ZnS quantum dots (Mn-ZnS QDs) as the signaling and recognition unit. The signal amplification was achieved by petal-like molybdenum disulfide nano sheets (MoS2 NS). As the selective adsorption of single-stranded DNA (ssDNA) on MoS2 NS, SDM-APT-Mn-ZnS QDs are assembled on the surface of MoS2 NS, and lead to the efficient phosphorescence quenching of Mn-ZnS QDs. Once SDM is brought in the sensing system, the specific interaction between SDM-APT and SDM will switch the conformation of SDM-APT from random coil to hairpin structure, resulting in the exfoliation of SDM-APT-Mn-ZnS QDs from MoS2 NS, along with the phosphorescence recovery. This SDM detection system has a linear range from 2.0 ng/mL to 400 ng/mL with LOD as 0.91 ng/mL (S/N = 3) at the optimal experimental condition. The feasibility, specificity and recovery have been verified from the detection of real samples, interfering experiments and standard recovery experiments. The SDM detection system may also be applied to other residual veterinary drugs with different aptamers.

Solochrome Dark Blue Azo Dye Removal by Sonophotocatalysis Using Mn2+ Doped ZnS Quantum Dots

This work investigates the degradation of the azo dye solochrome dark blue (SDB) by measurement of the photocatalytic, sonocatalytic and sonophotocatalytic activities, under low ultrasonic frequency (40 kHz) and UV-C (254 nm) light, using Mn-doped ZnS semiconductor quantum dots (Mn2+:ZnS Qds) as catalysts, prepared by a simple chemical precipitation procedure. In order to study the different morphological and optical crystal properties, various characterization techniques were used, such as high resolution transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffraction, N2 adsorption-desorption at −196 °C and ultraviolet-visible spectroscopy. The average particle size of the semiconductor Qds was in the range of 3–4 nm. The optimal parameters affecting dye degradation, such as the catalyst loading, solution pH, time of irradiation, initial concentration of dye, dopant concentration, ultrasonic power and frequency effect were evaluated. The synthesized catalytic material exhibited a high activity for sonophotocatalytic degradation of SDB (89%), larger than that observed for sonocatalysis (69.7%) or photocatalysis (55.2%) alone, which was due to the improved electron-holes separation, formation of more reactive radicals and enhancement of the active surface area. Qds showed good stability and reusability after five repeated cycles. Finally, the degradation products were identified by liquid chromatography-mass spectrometry (LC-MS).

Highly sensitive detection for alkaline phosphatase using doped ZnS quantum dots with room temperature phosphorescence and its logic gate function

This paper presents a highly sensitive sensing system for alkaline phosphatase by room temperature phosphorescence of Mn doped ZnS quantum dots and pyrophosphate. The sensing system has intense room temperature phosphorescence emission in the absence of alkaline phosphatase. The phosphorescence is quenched gradually with the addition of alkaline phosphatase. The emission “on” without alkaline phosphatase may be attributed to the increased probability of charge transfer from one of surface traps to the dopant bands of another resulted from the shortened dot-to-dot distance by the strong chelation of pyrophosphate and Zn2+ ion and the hydrogen bonding between pyrophosphate and β-cyclodextrin. The addition of alkaline phosphatase causes pyrophosphate hydrolyzed to orthophosphate and the dot-to-dot distance of quantum dots back to the normal, and then the phosphorescence “off”. The factors affecting the sensing system performance were also optimized. Under the optimal experimental conditions, the linear range for alkaline phosphatase is determined as 0.2−10 U/L with a LOD at 0.045 U/L. The recovery of human serum was determined from 93.75%–103.03%, indicating a potential application in biomedical diagnosis. Furthermore, an RTP-based “INHIBIT” logic gate using the doped ZnS quantum dots was also presented.

Engineering Cytochrome C with Quantum Dots and Ionic Liquids: A Win-Win Strategy for Protein Packaging against Multiple Stresses

Enhancing the structural stability and catalytic activity of Cytochorme c (Cyt C) against harsh process conditions would boost its use in biocatalysis. Herein, a new protein engineering strategy with improved efficacy is demonstrated through judicious task-specific functionalization of Cyt C with quantum dots (QDs) and ionic liquids (ILs). Mn2+ doped ZnS QD and ILs ([Cho][Ac]; [Cho][Dhp]) were concomitantly used to decorate Cyt C, which was characterized using various analytical tools. The peroxidase activity at room temperature of engineered Cyt C (Cyt C-QD-IL) increased markedly (1.2 to 3.5-fold) as compared to that for bare Cyt C, Cyt C with QD, and Cyt C with ILs. Further, Cyt C-QD-IL showed better catalytic activity under various stresses such as high temperature (110 °C), presence of a chemical denaturant (6 M GuHCl), high oxidative stress (30 min H2O2), and presence of proteases. Molecular docking results indicate that QD interacted with the active site of Cyt C and IL interacted with side chain amino acids via electrostatic and H-bonding interactions. Such favorable allosteric interactions might be behind the improved activity of Cyt C-QD-IL. The observed catalytic activity is in harmony with the structural stability of the protein as confirmed by UV–vis, ATR-IR, and CD analysis. Thus, the unveiled strategy represents an innovative dimension of protein packaging foreseeing the development of more robust biocatalysts that can be used at high temperatures.

A Ratiometric and Visual Sensing of Phosphate by White Light Emitting Quantum Dot Complex.

Ratiometric and visual sensing of phosphate by using a white light emitting quantum dot complex (WLE QDC) is reported herein. The WLE QDC comprised of Mn2+-doped ZnS quantum dot (with λem = 585 nm) and surface zinc quinolate (ZnQS2) complex (with λem= 480 nm). The limit of detection was estimated to be of 5.9 nM in the linear range of 16.6-82.6 nM. This was accomplished by monitoring the variations in the photoluminescence color, intensity ratio (I480/I585), chromaticity and hue of the WLE QDC in the presence of phosphate. The high selectivity and sensitivity of WLE QDC toward phosphate was observed. The chemical interaction of ZnQS2 (present in WLE QDC) with phosphate might have led to the observed specificity in photoluminescence changes. The presented WLE QDC was successfully employed for the quantification of phosphate in samples prepared using environmental water and commercial fertilizer.

Optical properties and energy transfer mechanism of Eu3+, Ce3+ doped and co-doped ZnS quantum dots

Semiconductor ZnS quantum dots (QDs) co-doped with Eu3+ and Ce3+ were synthesized by the chemical method. The optical properties of the samples were characterized by absorption spectroscopy, photoluminescence (PL) spectroscopy and PL-decay lifetime. X-ray diffraction revealed that the QDs had a zincblende structure and a particle size of about 3 nm. The presence of Eu3+ and Ce3+ ions in the samples were proved by X-ray photoelectron spectroscopy. The properties of ligand field and the intensity parameters of Eu3+ doped ZnS QDs were analyzed by Judd-Ofelt theory. For Ce3+ and Eu3+ ions co-doped in ZnS QDs, the luminescence intensity and lifetime of the 5d1 (Ce3+) level decrease while the emission intensity of Eu3+ ion increases with the increasing Eu3+concentration. The reduced lifetime and the luminescence quenching of the 5d1 (Ce3+) level are due to the energy transfer from Ce3+ to Eu3+ ion. The efficiency of the energy transfer process from Ce3+ ions to Eu3+ ions and the nature of this interaction mechanism were determined by applying Reisfeld and Inokuti-Hirayama models.

Mn-DOPPED ZnS QUANTUM DOTS AS SENSITIVE SENSOR FOR DETERMINATION OF CIPROFLOXACIN IN PHARMACEUTICAL AND BIOLOGICAL SAMPLES

A simple and fast spectrofluorimetric method for determination of ciprofloxacin based on its quenching effect on the fluorescence intensity of colloidal water ­soluble TGA ­caped, Mn doped ZnS quantum dots (QDs) has been described. The QDs having characteristic fluorescence spectra with maximum excitation at 315 nm followed by an emission peak at 632 nm were characterized using Energy Dispersive X-Ray and X-ray Diffraction techniques. The effect of various parameters such as concentration of QDs, time, pH, common excipients and metal ions on the quenching phenomenon was investigated. Fluorescence quenching was found to be maximum with 10 µg mL­-1 of QDs at pH 8 and fluorescence intensity was observed to be constant upto 45 min. The Stern­-Volmer calibration plot of F0/F as a function of ciprofloxacin concentration was found to be linear in the range of 0.5-10 µg mL­-1 with r² = 0.993. Under optimal experimental conditions the method was found to be interference free. The percent relative standard deviation of the proposed method calculated against method blank was found to be 1.10%. The limit of detection (LOD) and the limit of quantitation (LOQ) for Cf (signal to noise ratio 3:1 for LOD and 10:1 for LOQ) were calculated to be 0.15 and 0.50 μg mL-1 respectively. Average percent recoveries (±SD) obtained for spiked commercial formulations; ciprol and ciproquine, and serum and urine samples were found to be in the range of 92.2±1.8% to 99.5±1.5%, 90.5±1.2% to 96.7±1.4% and 94.0±1.2% to 98.5±1.4% respectively. The data evidently prove the potential of the proposed sensor QDs in biological analysis.

Optical properties of Silica capped Mn doped ZnS quantum dots

In the present report, silica capped ZnS quantum dots (QDs) have been synthesized using one-step Stober process. The bare Mn doped ZnS samples have been prepared by the co-precipitation method. The samples have then been coated by a SiO2 layer. X ray diffraction have been used to confirm the presence of desired phases and the absence of any impurity phase. The particle size and morphology have been studied through high resolution transmission electron microscopy (HRTEM). The absorption and the emission properties of the bare and the capped samples have been studied through UV-visible and photoluminescence spectroscopy respectively. Fourier-transform infrared (FTIR) spectroscopy was employed to study the band resonances of the samples.

Fabrication of a green and sensitive quantum dots based fluorescent probe for determination of sparfloxacin in biological samples and drug formulations

A simple and fast spectrofluorimetric method for determination of sparfloxacin (SPAR) based on fluorescence quenching of colloidal water soluble TGA caped, Mn doped ZnS quantum dots (QDs) has been described. The QDs having characteristic fluorescence spectra with maximum emission at 632 nm (Excitation at 315 nm) were characterized using Energy Dispersive x-ray and x-ray Diffraction techniques. The effect of various parameters such as concentration of QDs, time, pH, common excipients and metal ions on the quenching phenomenon was investigated. Fluorescence quenching was found to be maximum with 10 μg ml−1 of QDs at pH 7 with fluorescence intensity remaining constant upto 60 min. The Stern-Volmer calibration plot of F0/F as a function of sparfloxacin concentration was found to be linear in the range of 0.2–2.2 μg ml−1 with r2 = 0.995. Under optimal experimental conditions the method was found to be interference free. The percent relative standard deviation of the proposed method calculated against method blank was found to be 1.67%. The limit of detection and the limit of quantitation for SPAR (n = 3 and 10 respectively) were calculated to be 0.07 and 0.21 μg ml−1 respectively. Average percent recoveries (±SD) obtained were found to be 89.16 ± 0.03 to 94.44 ± 0.15 μg ml−1 for serum and 85.00 ± 0.10 to 97.77 ± 0.37 μg ml−1 for urine samples. In case of commercial formulations sparaxcin and spar, the maximum % recovery was found to 89.33 ± 0.54% while in case of Quspar the % recovery obtained was less than 71.83 ± 0.14%. The proposed method was statistically compared with reported chromatographic method and no significant difference was observed.

Optical Studies of Organically Functionalized Mn doped ZnS Quantum Dots

Organically functionalized manganese doped zinc sulfide (ZnS/Mn) quantum dots were prepared by simple chemical method with polypyrrole (PPy) used as a capping agent. Prepared quantum dots were characterized with Fourier transform infrared spectroscopy (FTIR), high resolution transmission electron microscopy (HR-TEM), X-ray diffraction microscope (XRD), UV-visible spectroscopy and photoluminescence spectroscopy. Crystalline size of PPy capped ZnS/Mn quantum dots for various concentrations of PPy were approximate 2 nm as analyzed by XRD and TEM analysis. The absorption spectra revealed the occurrence of a blue shift in the peak of absorption and an increase in the band gap value due to the quantum confinement effect. FTIR spectroscopy confirmed that shifting of broad peak at 2335.8 cm–1 was due to S-H stretching vibrations, which confirmed interaction of hydrogen and sulphur in ZnS/Mn/PPy nanocomposites. Uncapped ZnS/Mn and PPy capped ZnS/Mn quantum dots reveal the effective photoluminescence emission spectra in the range of 300-700 nm. With increase the value of capping agent in ZnS/Mn quantum dots, photoluminescence spectra going to red shifting. The photoluminescence properties of the organically functionalized ZnS nanoparticles are favourable for the application in optoelectronic devices.