Synthesis of organic solvent-free nitrogen-doped carbon quantum dots as unique green fluorimetric probes for analysis of abrocitinib in human plasma.

Atopic dermatitis (AD) is a persistent, inflammatory skin condition that impacts approximately 15 to 20% of children and 1 to 3% of adults globally. Common skin manifestations include papules, papulovesicular, and brown or red patches with swelling, crusting, and flaking. Therefore, the drug abrocitinib (ABR) was approved by the US FDA as an oral treatment for atopic dermatitis. The present study outlines the development of innovative, thermostable, and pH-stable organic solvent-free nitrogen-doped carbon dots (N@CQDs) synthesized through a one-step method for evaluating ABR with a notable quantum yield of 33.84% to minimize the use of organic solvents. Their cost-effectiveness, eco-friendly characteristics, and outstanding photocatalytic properties have established them as a promising alternative to conventional luminescent techniques like fluorescent dyes and luminous derivatization technique. The reaction of ABR with N@CQDs led to a significant decrease in the luminescent response of the produced green and stable carbon quantum dots at 513 nm. The detection range was determined to be 1.0-150.0 ng mL-1, with a lower limit of quantitation (LOQ) equal to 0.52 ng mL-1 based on the linear graph. The green method effectively used for analysis of ABR in pharmaceutical tablets and pharmacokinetic study with high sensitivity.

Design of new boron-doped carbon dots for nano-level assay of nebivolol in human plasma and commercial products; Application to greenness assessments.

Recently, nanomaterials have attracted a lot of attention due to their potential as effective fluorescent nano-sensor probes. They were distinguishing substitutes for other luminescent techniques, such as fluorescent dyes and luminous derivatization, because of their affordability, environmental friendliness, and special photocatalytic properties. In the suggested work, a straightforward method was used to create boron and nitrogen carbon dots (B@CDs) with a good quantum yield value of 31.15 % utilizing boric acid and di-sodium EDTA. For the purpose of characterizing QDs, a variety of instruments were employed, such as transmission electron microscopy, fluorescence spectroscopy, X-ray FTIR, and UV-VIS spectroscopy. Nebivolol (NEB) is a cardiovascular medication used globally to treat congestive heart failure and hypertension, is in the meantime. For this reason, a brand-new, environmentally friendly analytical technique was created to determine the amount of human plasma, uniformity test, and commercial nebivolol (NEB) tablets. After gradually adding NEB, the response of B@CQDs was enhanced at 438 nm (excitation at 371 nm). The calibration graph ranged between 20 and 500 ng mL-1 with a quantification limit (LOQ) of 2.50 ng mL-1 and a detection limit (LOD) of 0.82 ng mL-1.

Tracking the Variations in Trace and Heavy Elements in Smoking Products Marketed in Oman and Egypt: Risk Assessment After Implementation of Constraining Protocols.

Tobacco smoking is becoming one of the major worldwide concerns regarding environmental pollution as well as health threats. In 2005, the World Health Organization (WHO) released the Framework Convention On Tobacco Control (FCTC), which outlined protocols for controlling tobacco products. Oman was one of the leading countries to follow these protocols; however, Egypt has only followed these protocols recently in 2020. One of the main challenges in tobacco product control is the variation in their trace element's types and amounts from country to country owing to differences in agriculture techniques and used chemical additives. Smoking releases different toxic metal ions found in them into the air, and hence, analyzing trace amounts of metals in tobacco smoking products is becoming more critical. The proposed research aims to evaluate the current levels of 11 heavy metals (namely, As, Pb, Cd, Co, Cr, Be, Ba, Mn, Ni, Fe, and Hg) in 22 tobacco products available in Egypt and Oman using inductively coupled plasma optical emission spectroscopy and a direct mercury analyzer. Although some elements such as Be, Co, and Cd were absent, the positive detection of As and Pb and the levels of Ba, Cr, and Ni are still alarming, especially for heavy smokers. The obtained results were then statistically related to previously published data in 2017 to explore the effectiveness of implementing the FCTC protocols within the Egyptian market. The outcomes suggested a positive impact of FCTC protocol implementation in Egypt, besides the lower levels of elemental content for Omani products compared to the Egyptian market.

A new green fluorimetric micelle complexation approach for reduction of the consumed solvent and quantification of avapritinib in biological fluids.

Avapritinib (AVA) is the first medication authorized by the US-FDA in 2020 for the management of gastrointestinal stromal tumours (GISTs) that can't be treated by surgery. Cancer is among the most common causes of death worldwide and is the second most common cause of death after cardiovascular disease. Therefore, a quick, easy, sensitive, and straightforward fluorimetric approach was used to analyse AVA in pharmaceutical materials and blood plasma (pharmacokinetic). The suggested technique relies on 2% sodium dodecyl sulphate (SDS, pH 4) micellar system augmentation of the fluorescence of the tested drug. The technique demonstrated high relative fluorescence intensity (RFI) at 430 nm after excitation at 340 nm. Concentrations ranging from 20.0-400.0 ng mL-1 with a limit of quantitation of 9.47 ng mL-1 were used to obtain luminescence data for the studied medicine. In addition, the quantum yield of the AVA fluorescence was increased with the gradual addition of a surfactant at a concentration above its critical micellar level. This knowledge has been exploited to enhance the effectiveness of a spectrofluorometric technique for the estimation of AVA in human plasma (98.95 ± 1.22%) and uniformity tests with greenness assessments. The conditions for enhanced fluorescence were optimized and fully validated using US-FDA and International Conference on Harmonization (ICH) rules. This innovative strategy was expanded for AVA stability research in human plasma across various circumstances. This approach is an eco-friendly solution compared to traditional testing methods that use hazardous chemicals.

Design, Characterization, and Bioanalytical Applications of Green Terbium- and Nitrogen-Doped Carbon Quantum Dots as a Fluorescent Nanoprobe for Omadacycline Analysis.

Terbium- and nitrogen-doped carbon quantum dots (Tb,N@CQDs) were greenly created employing microwave synthesis from plum juice with terbium nitrate. The synthesis of Tb,N@CQDs was fast (7 min) with a high quantum yield (35.44%). Tb,N@CQDs were fully characterized using transmission electron microscopy, Zeta potential analysis, fluorescence, and ultraviolet spectroscopy. Omadacycline (OMC) is a broad-spectrum tetracycline that has been recently approved by the United States Food and Drug Act (FDA) in October 2018. OMC is the first oral aminomethylcycline class antibiotic drug that was authorized for the treatment of acute skin structure infections and community-acquired pneumonia. Tb,N@CQDs exhibited emission at 440 nm after excitation at 360 nm, where their fluorescence intensity showed a reduction upon addition of OMC. The experimental parameters were further studied and optimized. The linear range was between 40 and 60 parts per billion (ppb), with (limit of quantitation) equal to 34.78 ppb. The proposed approach was validated for bioanalytical purposes using FDA guidelines and proved to be straightforward, cheap, highly sensitive, and very selective, which can be used in clinical studies. The developed approach proved to be green using some current assessment metrics and was applied successfully for the determination of OMC in human plasma, milk, and pharmaceutical formulations as well as pharmacokinetic study.

An Innovative Selective Fluorescence Sensor for Quantification of Hazardous Food Colorant Allura Red in Beverages Using Nitrogen-Doped Carbon Quantum Dots.

An innovative simple, sensitive, and selective method has been developed and validated for quantification of hazardous Allura red (AR, E129) dye in beverages. Allura red (AR) is a synthetic dye that is commonly used in the food industry to give foods a bright and appealing color. The method is based on microwave-assistant nitrogen-doped carbon quantum dots (N@CQDs) from a very cheap source with a high quantum yield equal to (36.60%). The mechanism of the reaction is based on an ion-pair association complex between AR and nitrogen-doped carbon quantum dots (N@CQDs) at pH 3.2. The reaction between AR and N@CQDs led to a quenching effect of the fluorescence intensity of N@CQDs at 445 nm after excitation at 350 nm. Moreover, the quantum method's linearity covered the range between 0.07 and 10.0 µg mL- 1 with a regression coefficient is 0.9992. The presented work has been validated by ICH criteria. High-resolution transmission electron microscopy (HR-TEM), X-ray photon spectroscopy (XPS), Zeta potential measurements, fluorescence, UV-VIS, and FTIR spectroscopy have all been used to fully characterize of the N@CQDs. The N@CQDs were successfully utilized in different applications (beverages) with high accuracy.

Medial deviation of the ureter is a new sign that could predict stone impaction: a pilot study.

OBJECTIVE: To assess the value medial deviation of the ureter at site of ureteric stone as a sign of ureteric stone impaction. PATIENTS AND METHODS: All cases with medial deviation of the ureter at site of ureteric stones in our department over 4 years were enrolled in this pilot study. All cases were diagnosed with KUB and non-contrast CT (NCCT). Radiological and ureteroscopic findings were recorded. RESULTS: A total of 32 patients with a single impacted stone in the proximal and middle third of the ureter were included in the study. Medial deviation of the ureter at the site of the stone was detected in the upper third of the ureter in 24 (75%) cases and in the middle third in 8 (25%) cases. There were mucosal polyps and mucosal erythema (inflammatory changes) seen by ureteroscopy in all cases (100%). Ureteroscopy was successfully completed with stone fragmentation in 23 (71.8%) patients: 8 of them needed ureteric catheter and 15 required JJ stent insertion. Failure of ureteroscopy with insertion of JJ stent was done in 5 (15.6%) patients. Removal of the stent and ureteroscopy was done after 4 weeks. CONCLUSION: We conclude from this study that medial deviation of the ureter is a new reliable radiological sign of ureteric stone impaction.

Green microwave quantum dots as luminescent probes for quantifying prucalopride: consistency of content and application to pharmacokinetic studies.

Prucalopride (PCP) is a medication used for the management of constipation via regulating bowel motions. PCP is widely used all over the world. So, novel, rapid, and highly sensitive carbon dots N-CQDs were obtained from Eruca Sativa juice via microwave approach in 4 min. The luminescence power of N-CQDs was declined by the increasing prucalopride concentration at emission 518 nm with linearity ranged from 3.00 to 200.00 ng mL-1. The luminescent antecedent was utilized for the test of PCP in human plasma with the rate of recovery extending from 95.06 to 98.40%. The new technique is an eco-friendly analytical method that can be easily applied in clinical laboratories. This assay is also simple, sensitive, and applied to therapeutic laboratories and subsequent pharmacokinetic studies in several clinical laboratories. Furthermore, the N-CQDs nano-sensor was able to distinguish the target drug from interferents commonly found in human plasma, indicating its high specificity and selectivity for PCP detection.

Fast and Sensitive Bioanalytical Method for the Determination of Deucravacitinib in Human Plasma Using HPLC-MS/MS: Application and Greenness Evaluation.

Plaque psoriasis is a common, long-lasting illness that affects the immune system and causes significant negative impacts on a patient's physical health, well-being, and ability to work effectively. Deucravacitinib (DEU) is the first oral medication used in the treatment of plaque psoriasis, a chronic skin condition that causes red, scaly patches on the skin. DEU is a type of medication called an oral Janus kinase (JAK) inhibitor, which works by blocking specific enzymes that play a role in the inflammation and immune response associated with psoriasis. Therefore, a quick, easy, novel, reliable, sensitive, and straightforward liquid chromatography-tandem mass spectrometry (LC-MS/MS) approach was used to analyze DEU in plasma samples. The LC-MS/MS method for the determination of DEU in human plasma was based on using trimethoprim as an internal standard (IS). The separation of DEU and IS was carried out via liquid-liquid extraction (LLE). The extract was then subjected to the chromatographic system separation using the ACE-C18 column (4.6 × 100 mm, 5 µm). The mobile phase employed consisted of methanol and a solution of 2 mM ammonium formate (80:20 v/v, respectively). The flow rate used was set at 0.9 mL min-1. The creative strategy was performed by running an ABSCIEX API 4000 mass spectrometer with an electron spray ionization source in multiple reaction monitoring (MRM) mode. The ion transitions m/z 426.3 → 358.2 were used for DEU quantitation, while the ion transitions m/z 291.1 → 261.1 were used for trimethoprim quantitation. The accuracy, precision, linearity, recovery, and selectivity of DEU were deemed acceptable when validated for a concentration range between 0.500 and 601.050 ng/mL, utilizing a weighting factor of 1/x2.

Development of cysteine-doped MnO2 quantum dots for spectrofluorimetric estimation of copper: applications in different matrices.

Copper (Cu) plays a role in maintaining healthy nerve cells and the immune system. Osteoporosis is a high-risk factor for Cu deficiency. In the proposed research, unique green, fluorescent cysteine-doped MnO2 quantum dots (Cys@MnO2 QDs) were synthesized and assessed for the determination of Cu in different food and hair samples. The developed quantum dots were synthesized with the help of cysteine using a straightforward ultrasonic approach to create 3D fluorescent Cys@MnO2 QDs. The resulting QDs' morphological and optical characteristics were carefully characterized. By adding Cu ions, the intensity of fluorescence for the produced Cys@MnO2 QDs was found to be dramatically reduced. Additionally, the applicability of Cys@MnO2 QDs as a new luminous nanoprobe was found to be strengthened by the quenching effect grounded on the Cu-S bonding. The concentrations of Cu2+ ions were estimated within the range of 0.06 to 7.00 µg mL-1, with limit of quantitation equal to 33.33 ng mL-1 and detection limit equal to 10.97 ng mL-1. The Cys@MnO2 QD technique was applied successfully for the quantification of Cu in a variety of foods, including chicken meat, turkey, and tinned fish, as well as in human hair samples. The chance that this novel technique could be a useful tool for figuring out the amount of cysteine in bio-samples is increased by the sensing system's remarkable advantages, which include being rapid, simple, and economical.

Recent advances in chiral selectors immobilization and chiral mobile phase additives in liquid chromatographic enantio-separations: A review.

For decades now, the separation of chiral enantiomers of drugs has been gaining the interest and attention of researchers. In 1991, the first guidelines for development of chiral drugs were firstly released by the US-FDA. Since then, the development in chromatographic enantioseparation tools has been fast and variable, aiming at creating a suitable environment where the physically and chemically identical enantiomers can be separated. Among those tools, the immobilization of chiral selectors (CS) on different stationary phases and the chiral mobile phase additives (CMPA) which have been progressed and studied extensively. This review article highlights the major advances in immobilization of CS together with their different recognition mechanisms as well as CMPA as a cheaper and successful alternative for chiral stationary phases. Moreover, the role of molecular modeling tool as a pre-step in the choice of CS for evaluating possible interactions with different ligands has been pointed up. Illustrations of reported methods and updates for immobilized CS and CMPA have been included.

Applicability of fluorescamine as a fluorogenic reagent for highly sensitive fluorimetric analysis of the tyrosine kinase inhibitor (avapritinib) in pharmaceuticals and biological samples.

Avapritinib (AVP) was the first precision drug to be approved by the US Food and Drug Administration (FDA) in 2020 for patients suffering from metastatic gastrointestinal stromal tumors (GISTs) and progressive systemic mastocytosis. The analysis of AVP in pharmaceutical tablets and human plasma was then carried out using a fast, efficient, sensitive, and simple fluorimetric method using a fluorescamine reagent. The procedure is based on the interaction between fluorescamine as a fluorogenic reagent and the primary aliphatic amine moiety in AVP using borate buffer solution at pH 8.8. The produced fluorescence was measured at 465 nm (Excitation at 395 nm). The calibration graph's linearity range was discovered to be 45.00-500.0 ng mL-1 . Utilizing the International Council for Harmonization (ICH) and US-FDA recommendations, the research technique was validated and bioanalytically validated. The proposed approach was effectively employed for determining the stated pharmaceuticals in plasma with a high percentage of recovery ranging from 96.87 to 98.09 and pharmaceutical formulations with a percentage of recovery equal to 102.11% ± 1.05%. In addition, the study was extended to a pharmacokinetic study of AVP with 20 human volunteers as a step for AVP management in therapeutic cancer centers.

Early versus delayed penile prosthesis insertion for refractory ischemic priapism.

Objectives: Penile prosthesis insertion is a well-established therapeutic option in refractory ischemic priapism but there is a lack of standardization regarding the timing of surgery, the type of prosthesis (malleable or inflatable), as well as the possible complications. In this study, we retrospectively compared early versus delayed penile prosthesis insertion in patients with refractory ischemic priapism. Methods: 42 male patients who presented with refractory ischemic priapism during the period between January 2019 and January 2022 were included in this study. All patients had malleable penile prosthesis insertion by four highly experienced consultants. Patients were divided into two groups based on the time of the prosthesis insertion. 23 patients had immediate insertion of the prosthesis within the first week of the onset of priapism while the remaining 19 patients had delayed prosthesis insertion three months or later after the onset of priapism. The outcome as well as the intra- and the postoperative complications were recorded. Results: Postoperative complications such as prosthesis erosion and infection were higher among the early insertion group while the delayed insertion group had higher incidence of intraoperative complications such as corporal perforation and urethral injury. The insertion of the prosthesis was much more difficult among the delayed insertion group due to fibrosis which made dilatation of the corpora very difficult. The length and the width of the penile implant were significantly higher among the early insertion group as compared to the delayed insertion group. Conclusions: Early penile prosthesis insertion for refractory ischemic priapism is a safe and effective treatment option as delayed prosthesis insertion is more difficult and challenging due to corporal fibrosis and is associated with higher complication.

Zinc(II) complexation strategy for ultra-sensitive fluorimetric estimation of molnupiravir: Applications and greenness evaluation.

The endemicity of the pandemic coronavirus disease 2019 (COVID-19) infection proved to be transitional only. Spikes are forming again in 2023, and high expectations are returning for reinfections and viral mutations. Molnupiravir (MOL) has been approved as an oral antiviral drug for the treatment of the COVID-19 causative virion. Therefore, the development of an ultrasensitive, instantaneous, and cost-effective method for the quantification of MOL in real plasma samples and formulated dosage form are mandatory. The proposed approach is based on the synthesis of a MOL metal-chelation product. MOL as a ligand was chelated with 1.0 mM zinc(II) in an acetate buffer (pH 5.3). After illumination at 340 nm, the intensity of the MOL fluorescence measured at 386 nm was increased by about 10-fold. The linearity range was found to be from 60.0 to 800.0 ng mL-1 with limit of quantitation (LOQ) of 28.6 ng mL-1 . Two methods were utilized for measuring the greenness of the proposed method (Green Analytical Procedure Index [GAPI] and analytical greenness metric [AGREE] methods), with results equal to 0.8. The binding stoichiometry of MOL with the zinc(II) ion was found to be 2:1. All the experimental parameters were optimized and validated using International Conference on Harmonization (ICH) and United States Food and Drug Administration (US-FDA) recommendations. Furthermore, the fluorescent probes were successfully utilized in real human plasma with high percentages of recovery (95.6%-97.1%) without any matrix interferences. The mechanism of fluorescent complex formation was confirmed using 1 H NMR in the presence and absence of Zn(II). The method was further utilized for testing content uniformity of MOL in its marketed capsule dosage forms.

A Novel Design Eco-friendly Microwave-assisted Cu-N@CQDs Sensor for the Quantification of Eravacycline via Spectrofluorimetric Method; Application to Greenness Assessments, Dosage Form and Biological Samples.

Community-acquired pneumonia is one of the most common infectious diseases and a substantial cause of mortality and morbidity worldwide. Therefore eravacycline (ERV) was approved by the FDA in 2018 for the treatment of acute bacterial skin infections, GIT infections, and community-acquired bacterial pneumonia caused by susceptible bacteria. Hence, a green highly sensitive, cost-effective, fast, and selective fluorimetric approach was developed for the estimation of ERV in milk, dosage form, content uniformity, and human plasma. The selective method is based on the utilization of plum juice and copper sulphate for the synthesis of green copper and nitrogen carbon dots (Cu-N@CDs) with high quantum yield. The quantum dots' fluorescence was enhanced after the addition of ERV. The calibration range was found to be in the range 1.0 - 80.0 ng mL-1 with LOQ equal to 0.14 ng mL-1 and LOD was found to be 0.05 ng mL-1. The creative method is simple to deploy in clinical labs and therapeutic drug health monitoring system. The current approach has been bioanalytically validated using US-FDA and validated ICH criteria. High-resolution transmission electron microscopy (HR-TEM), X-ray photon spectroscopy (XPS), Zeta potential measurements, fluorescence, UV-VIS, and FTIR spectroscopy have all been used to fully characterize the Cu-N@CQDs. The Cu-N@CQDs were effectively applied in human plasma and milk samples with a high percentage of recovery ranging from 97.00 to 98.80%.

Toxic Elemental Impurities in Herbal Weight Loss Supplements; A Study Using ICP-OES Microwave-Assisted Digestion.

The tendency of using weight loss herbal preparations is continuously increasing, especially for the widespread consumption of junk food that is characterized by high calories. Weight loss herbal preparations are considered a type of food supplement product, and, as such, the regulations governing their quality control might be minimal. These products could be locally formulated in any country or internationally imported. Being non-controlled products, the herbal weight-loss products may contain high levels of elemental impurities that might exceed the permissible ranges. Moreover, these products contribute to the total daily intake (TDI) of such elements, which might represent concerns about their potential toxicological danger. In this research, the elemental contents in such products were investigated. The inductively coupled plasma with optical emission spectrometer (ICP-OES) was used to determine the levels of 15 elemental contents, namely, Na, K, Ca, Mg, Al, Cu, Fe, Li, Mn, As, Co, Cr, Cd, Ni and Pb. The results showed that seven micro-elements, namely Cd, Co, Ni, Cr, Pb, Li and Cu, were either not detectable or at a concentration much lower than their tolerable limits. However, all studied macro-elements (Na, K, Ca and Mg), together with Fe, were found at considerable, yet safe levels. On the other hand, Mn, Al and As contents showed perturbing levels in some of the studied products. Finally, a conclusion was highlighted for the necessity for stricter surveillance of such herbal products.

An Innovative Polymer-Based Electrochemical Sensor Encrusted with Tb Nanoparticles for the Detection of Favipiravir: A Potential Antiviral Drug for the Treatment of COVID-19.

An innovative polymer-based electro-sensor decorated with Tb nanoparticles has been developed for the first time. The fabricated sensor was utilized for trace determination of favipiravir (FAV), a recently US FDA-approved antiviral drug for the treatment of COVID-19. Different techniques, including ultraviolet-visible spectrophotometry (UV-VIS), cyclic voltammetry (CV), scanning electron microscope (SEM), X-ray Diffraction (XRD) and electrochemical impedance spectroscopy (EIS), were applied for the characterization of the developed electrode TbNPs@ poly m-THB/PGE. Various experimental variables, including pH, potential range, polymer concentration, number of cycles, scan rate and deposition time, were optimized. Moreover, different voltammetric parameters were examined and optimized. The presented SWV method showed linearity over the range of 10-150 × 10-9 M with a good correlation coefficient (R = 0.9994), and the detection limit (LOD) reached 3.1 × 10-9 M. The proposed method was applied for the quantification of FAV in tablet dosage forms and in human plasma without any interference from complex matrices, obtaining good % recovery results (98.58-101.93%).

A single center comparative study of two single use digital flexible ureteroscopy in the management of renal stones less than 2 cm.

PURPOSE: For renal stones < 2 cm, guidelines recommend the use of retrograde intrarenal surgery as a first line treatment option. Many available single use flexible ureteroscopy were found. We aim to compare the effectiveness of two single use flexible ureteroscopy; Pusen Uscope 3011 versus LithoVue in the management of renal stones less than 2 cm. METHODS: Our study prospectively included 60 patients equally divided in to two groups: Pusen group and LithoVue group during the period from June 2020 to June 2021. The included patients were above 18 years old. Perioperative details as operative time, fluoroscopy time, hospital stay, and complications were recorded. Stone free rate was assessed. Base purchase cost was also compared. RESULTS: There was no statistically significant difference between the two groups regarding age, gender, and body mass index (BMI), stones size, side, number and location. The perioperative evaluation and outcome had no statistically significant differences between the two groups regarding the operative time, hospital stay, access sheath use, and stone free rate or radiation exposure. Among all cases, we had 49 cases (81.6%) with no postoperative complications (21 cases for Pusen group and 28 cases for LithoVue group). The incidence of postoperative complications was significantly higher among Pusen group than LithoVue group (p = 0.02). Initial purchase cost for both FURS had no significant difference (P = 0.86). CONCLUSION: RIRS can be performed effectively with Pusen 3011 and LithoVue single use flexible ureteroscopy in patients diagnosed with renal calculi < 2 cm with superior outcomes with LithoVue.

Ultrasensitive green spectrofluorimetric approach for quantification of Hg(II) in environmental samples (water and fish samples) using cysteine@MnO2 dots.

Mercury (Hg2+ ) is a natural element present in foods such as fish, water and soil. Exposure to mercury leads to severe toxic effects on the nervous, digestive, and immune systems. Here, a novel, green, and environmentally friendly fluorescent probe decorated with cysteine/MnO2 quantum dots (Cys@MnO2 QDs) was synthesized. This synthesis was carried out using a simple ultrasound technique with the aid of cysteine for fabricating Cys@MnO2 QDs to estimate Hg levels in fish and water samples. In this morphological study, Cys@MnO2 QDs were fully characterized using high-resolution transmission electron microscopy, zeta potential analysis, fluorescence, ultraviolet-visible and infrared spectroscopy. The fluorescence of the synthesized Cys@MnO2 QDs was significantly quenched by gradually increasing the Hg(II) concentration. The quenching mechanism based on the Hg-S bonds strengthened the utility of the Cys@MnO2 QDs as a novel luminescent nanoprobe. The estimation of Hg was linear in the concentration range 0.7-100.0 ng mL-1 with a limit of quantitation equal to 0.30 ng mL-1 . The Cys@MnO2 QDs are fluorescent probes with various benefits such as speed, ease of use, cost- effective, and being environmentally friendly; they are easily applied in food manufacturing and for public health improvement.