The portable stochastic sensor as a screening tool for simultaneous determination of HER-1 and CA 125 - a key factor in the rapid recognition of gastric cancer.

The significance of HER-1 and CA 125 lies in their ability to guide cancer diagnosis, treatment, and monitoring, improving personalized care and enhancing prognostic accuracy. The utilization of HER-1 and CA 125 as screening biomarkers for the anticipation of early-stage cancer and monitoring cancer progression is expanding due to the invasive and costly nature of present techniques. In this study, a novel stochastic sensor was developed for the simultaneous determination of HER-1 and CA 125 in whole blood, saliva, and gastric tumor tissue samples using a fast, easy, inexpensive, and portable method. The stochastic sensor was prepared by electropolymerization of cysteine on the surface of the Au-TiO2@rGO/SPCE sensor. The Au-TiO2@rGO nanocomposite was synthesized using a simple chemical reduction process. The proposed sensor showed wide linear concentration ranges and very low limits of quantification (LOQ). The concentration ranges were from 3.9 × 10-14 to 3.9 × 10-8 µg mL-1, with a LOQ of 3.9 × 10-14 µg mL-1 for HER-1. For CA 125, the concentration ranges were from 8.3 × 10-14 to 8.3 × 10-10 U mL-1, with a LOQ of 8.3 × 10-14 U mL-1. Both biomarkers exhibit precise discrimination in different biological samples, with recoveries above 96.78% and RSD values below 0.04%. With a confidence level of 99%, the Student t-test revealed that there is no statistically significant difference between the outcomes obtained by using the poly-Cys/Au-TiO2@rGO/SPCE sensor for screening examinations of biological samples. This was determined because the results were not significantly different from one another.

Fast screening of Milk for Deoxynivalenol.

A 2D platform was designed and validated for fast screening of milk for deoxynivalenol. The qualitative and quantitative assay of deoxynivalenol in the milk samples was done using a 2D stochastic sensor based on single walled carbon nanotubes modified with [N-(pyridine-4-yl-methyl)]octadec-9-enamide. The working concentration range was between 10-15 and 10-6 g mL-1, with a sensitivity of 5.48 × 105 s-1g-1mL, and a limit of determination of 1 fg mL-1. Recovery values higher than 99.00 % with RSD values lower than 1.00 % were recorded for the determination of deoxynivalenol in cow's and in the vegetarian (coconut milk, soy milk, almond milk) milk.

Determination of Matrix Metalloproteinase 2 in Biological Samples Using a 3D Stochastic Microsensor Based on Graphene Oxide/AuNanoparticles/(Z)-N-(pyridin-4-yl-methyl) Octadec-9-enamide.

The levels of the MMPs in the biological samples of confirmed patients with gastric cancer are significantly elevated compared to those found in healthy people. Therefore, a novel 3D stochastic microsensor based on graphene oxide, modified with gold nanoparticles and (Z)-N-(pyridin-4-yl-methyl) octadec-9-enamide (namely N2-AuNP/GO), was designed for the determination of MMP-2 in biological samples, and validated for the screening tests of biological samples in order to be used for the early diagnosis of gastric cancer. The proposed sensor presents a low limit of quantification (1.00 × 10-22 g mL-1), high sensitivity (1.84 × 107 s-1 g-1 mL), and a wide working concentration range (1.00 × 10-22-1.00 × 10-7 g mL-1). Recovery values higher than 99.15% were recorded for the assay of MMP-2 in whole blood, gastric tissue tumors, saliva, and urine samples.

Pathological Features of Colorectal Adenocarcinoma Patients Related to MLH1.

Background: MLH1, one of the MMR proteins, is linked to DNA replication, its role being to repair the incorrect DNA sequences and to replace them with proper ones. The loss of the MLH1 gene expression is part of Lynch syndrome which can lead to a series of cancers like colorectal and endometrial ones. The aim of this paper is to correlate the levels of MLH1 in four different bio-logical fluids with clinicopathological features in colorectal cancer patients in order to predict them with high probability. Therefore, a mathematical model with given code in Matlab has been proposed to get the clinicopathological features with high probability by only introducing the values for MLH1 concentrations. All these data can be obtained in a very short time even before surgery which can be very helpful the surgeon and the oncologist. Methods: Four types of samples (whole blood, saliva, urine and tissue) were analyzed using stochastic microsensors; concentrations of MLH1 were determined and compared with different macroscopic and micro-scopic pathological features to obtain mathematical models for early, non-invasive diagnostic of colorectal adenocarcinoma. Results: There have been established criteria and mathematical models for tumor location, TNM grading system, depth of the tumor, lymphatic, vascular and perineural invasions and the presence of mucus in the tumoral mass. Conclusions: By using whole blood, saliva and urine samples, the location can be approximated. The proposed mathematical models aimed to allow a minim/noninvasive characterization of the tumor and its location which can help the surgeon and the oncologist to choose faster the personalized treatment.

Disposable Stochastic Miniplatforms for Simultaneous Recognition and Determination of Vitamins B5, B7, and B9 in Food and Pharmaceutical Compounds.

Vitamins are essential for supporting daily physiological functions and are crucial for metabolic processes, including preventing vascular events and delaying the progression of diabetic nephropathy. The specific assessment of food and pharmaceutical compound quality requires the highly sensitive evaluation of vitamins B5, B7, and B9. Therefore, it is necessary to have a fast screening method for multivitamin tablets, pharmaceutical tablets, water, food, including raw egg yolk, and biological fluids, including urine, in order to ensure the precise identification and measurement of vitamins B5, B7, and B9. This paper introduces a novel disposable stochastic miniplatform that utilizes an incorporated 2D stochastic sensor to be able to simultaneously assay the three vitamins. Cobalt-phthalocyanine was used to modify the carbon film of the 2D sensor. High sensitivities (of 102-108 s-1 g-1 mL magnitude order) and low detection limits (of pg mL-1 magnitude order) were recorded for the disposable stochastic miniplatforms. The validation procedure involved the utilization of pharmaceutical tablets, supplement tablets, water samples, food samples, including raw egg yolk, and biological samples, specifically urine. The disposable stochastic miniplatforms demonstrate cost-effectiveness and suitability for the fast screening tests, with a time frame of 6 min, across a range of samples, a capacity of over 150 measurements, and an endurance of up to one month. Recovery values higher than 94.00% with RSD (%) values lower than 1.00 were recorded.

Correlations between MSH2 and MSH6 Concentrations in Different Biological Fluids and Clinicopathological Features in Colorectal Adenocarcinoma Patients and Their Contribution to Fast and Early Diagnosis of Colorectal Adenocarcinoma.

(1) Background: The human MutS homolog, hMSH2, is known to be involved in DNA mismatch repair and is responsible for maintaining the stability of the genome. When DNA damage occurs, MSH2 promotes cell apoptosis via the regulation of ATR/Chk2/p53 signal transduction, and MSH2 deficiency is also related to accelerated telomere shortening in humans. MSH2 missense mutations are involved in a defective DNA reparation process, and it can be implied in carcinogenesis, as it is already involved in well-known cancer-related syndromes such as Lynch syndrome. Human MSH6, which stands for mutS homolog 6, is a member of the MMR family that is responsible for the repair of post-replicative mismatched DNA bases. It is also one of the proteins with gene mutations that are associated with a high risk of developing Lynch syndrome, leading to a large series of tumors. (2) Methods: Patients and their clinical and pathological features were selected from the database of the project GRAPHSENSGASTROINTES and used accordingly, with ethics committee approval no. 32647/2018 awarded by the County Emergency Hospital from Targu-Mures. Analyses were conducted on whole blood, saliva, urine, and tumoral tissue samples using a stochastic method with stochastic microsensors. (3) Results: The results obtained using stochastic sensors were correlated with a series of macroscopic and microscopic pathological features for each sample type. Criteria or relationships were established for tumor location, vascular and perineural invasions, lymph node metastases, the presence of tumor deposits, and the presence of a mucus compound in the tumor mass. (4) Conclusions: The correlation between the concentrations of MSH2 in the four types of samples and the pathological features allowed for the fast characterization of a tumor, which can help surgeons and oncologists choose personalized treatments. Also, the colorectal tumor location was correlated with the concentration of MSH2 in whole blood, urine, and saliva. MSH6, which stands for mutS homolog 6, is not only useful in immunohistochemistry but in pathology practice as well. In this paper, the relationships between MSH6 levels in four biological fluids-whole blood, saliva, urine, and tissues-and tumor locations among the colorectal area, gross features, presence of a mucinous compound, molecular subtype, stroma features, and vascular invasions are presented.

Simultaneous Assay of CA 72-4, CA 19-9, CEA and CA 125 in Biological Samples Using Needle Three-Dimensional Stochastic Microsensors.

Two-needle 3D stochastic microsensors based on boron- and nitrogen-decorated gra-phenes, modified with N-(2-mercapto-1H-benzo[d]imidazole-5-yl), were designed and used for the molecular recognition and quantification of CA 72-4, CA 19-9, CEA and CA 125 biomarkers in biological samples such as whole blood, urine, saliva and tumoral tissue. The NBGr-2 sensor yielded lower limits of determination. For CEA, the LOD was 4.10 × 10-15 s-1 g-1 mL, while for CA72-4, the LOD was 4.00 × 10-11 s-1 U-1 mL. When the NBGr-1 sensor was employed, the best results were obtained for CA12-5 and CA19-9, with values of LODs of 8.37 × 10-14 s-1 U-1 mL and 2.09 × 10-13 s-1 U-1 mL, respectively. High sensitivities were obtained when both sensors were employed. Broad linear concentration ranges favored their determination from very low to higher concentrations in biological samples, ranging from 8.37 × 10-14 to 8.37 × 103 s-1 U-1 mL for CA12-5 when using the NBGr-1 sensor, and from 4.10 × 10-15 to 2.00 × 10-7 s-1 g-1 mL for CEA when using the NBGr-2 sensor. Student's t-test showed that there was no significant difference between the results obtained utilizing the two microsensors for the screening tests, at a 99% confidence level, with the results obtained being lower than the tabulated values.

Bioanalysis of MMR and KRAS - a key factor in diagnosis of colorectal cancer.

Two miniaturized electrochemical devices were designed for the simultaneous bioanalysis of MMR (MLH1, MSH2, MSH6, PMS2), and of KRAS in whole blood, urine, saliva, and tumoral tissues. The devices comprised besides the electronic part of the potentiostat a combined 3D stochastic microsensor (combined microplatform) with the sensing part based on the modification of graphene decorated with nitrogen, sulfur and boron (NSB-EGR) modified with two types of frutafit: FTEX and FHD. For the assay of MSH2, MSH6, KRAS, and PMS2 higher sensitivities were recorded when the microdevice based on FHD was used, while for the assay of MLH1 the best sensitivity was achieved by using the microdevice based on FTEX. While the limits of quantification for MLH1, MSH2, and PMS2 were not influenced by the modifier, the microdevice based on FHD provided the lowest limit of quantification for KRAS, the microdevice based on FTEX provided the lowest limit of quantification for MSH6. The validation tests performed proved that recoveries of MLH1, MSH2, MSH6, PMS2, and of KRAS in whole blood, urine, saliva, and tumoral tissues higher than 98.50% with RSD (%) values lower than 0.10% were recorded.

New stochastic devices for simultaneous analysis of mismatch repair proteins and KRAS in biological samples.

Two stochastic microsensors based on the immobilization of inulins: inutec and frutafit in a paste obtained from a graphene decorated with nitrogen (10.8 %), and boron (2.6 %), and paraffin oil (IR purity) were designed, characterized and validated for the molecular recognition and analysis of mismatch repair proteins like MLH1, MSH2, MSH6, PMS2, and of KRAS in biological samples such as: whole blood, urine, saliva, and tumoral tissues. The sensor based on inutec exhibited the largest working concentration range (10 decades of concentration) and the lowest limit of determination (0.32fg mL-1) when used for the assay of MLH1, and the wider working concentration range (8 decades of concentration), and the lowest limit of determination (2.30fg mL-1) when used for the assay of MSH6. The sensor based on frutafit exhibited the largest working concentration range (10 decades of concentration) when used for the determination of KRAS, and the wider working concentration range (5 decades of concentration), and the lowest limit of determination (1.00fg mL-1) when used for the assay of PMS2. No influence of the modifier (inutec and frutafit) was recorded on the linear concentration range (10 decades of concentration), and on the limit of determination (1.00 fg mL-1) for the assay of MSH2. The recoveries of MLH1, MSH2, MSH6, PMS2, and of KRAS in whole blood, urine, saliva, and tumoral tissues were higher than 98.00 with RSD (%) values lower than 0.10 %.

Stochastic platform based on calix[6]arene and TiO2-modified reduced graphene oxide electrode for on-site determination of nonivamide in pharmaceutical and water samples.

Using a detection platform based on an integrated sensor constructed by modifying TiO2 and reduced graphene oxide paste with calix[6]arene, a novel stochastic approach for both quantitative and qualitative analysis of nonivamide in pharmaceuticals and water samples has been developed. A wide analytical range of 1.00 × 10-18 to 1.00 × 10-1 mol L-1 was obtained with the stochastic detection platform for nonivamide determination. A very low limit of quantification of 1.00 × 10-18 mol L-1 was reached for this analyte. The platform was successfully tested on real samples, respectively, on topical pharmaceutical dosage form and surface water samples. The samples were analyzed without pretreatment in the case of pharmaceutical ointment or under minimal preliminary processing for surface waters proving a facile, rapid, and reliable method. Moreover, being portable, the developed detection platform is adequate for on-site analysis in various sample matrices.

Minimally Invasive and Fast Diagnosis of Gastric Cancer Based on Maspin Levels in Different Biological Samples.

(1) Background: Human SERPINB5, commonly known as maspin, has diverse functions as a tumor suppressor. Maspin has a novel role in cell cycle control, and common variants were discovered to be associated with gastric cancer (GC). Maspin was proven to also affect the EMT and angiogenesis of gastric cancer cells via the ITGB1/FAK pathway. Information about the maspin concentrations correlated with different pathological features of the patients may facilitate the fast diagnosis and personalized treatment of patients. The novelty of this study is given by the correlations established for the maspin levels in different biological features and clinicopathological features. These correlations can be extremely useful for surgeons and oncologists. (2) Patients and methods: Patients with clinical and pathological features, given the small number of samples available for this study, were selected from the database of the project GRAPHSENSGASTROINTES, and used in accordance with the Ethics Committee approval nr. 32,647/2018 awarded by the County Emergency Hospital from Targu-Mures. Stochastic microsensors were used as new screening tools for the determination of the concentration of maspin in four types of samples: tumoral tissues, blood, saliva and urine. (3) Results: The results obtained using the stochastic sensors were correlated with those tabulated in the clinical and pathological database. A series of assumptions regarding the values and practice important features for surgeons and pathologists were made. (4) Conclusions: This study provided a few assumptions regarding the correlations between the values of maspin levels in the analyzed samples and the clinical and pathological features. These results may be useful as preoperative investigations in order to help surgeons localize, approximate and choose the best treatment. These correlations may facilitate minim invasive and fast diagnosis of gastric cancer based on reliable detection of maspin concentration in biological samples (tumoral tissues, blood, saliva and urine).

Nanoplatform-based analysis for the detection of HER3 and HER4 for gastric cancer diagnosis.

Nanographene andα-cyclodextrin based sensors modified with gold nanoparticles and spheroidal copper were used to develop two stochastic sensors, which were then characterized and validated for the purpose of molecularly identifying and quantifying HER3 and HER4 in biological samples. In order to accomplish this goal, each of the stochastic sensors was incorporated in a nanoplatform. The two nanoplatforms were connected to a smartphone and recorded very low limits of determination (1 × 10-15g ml-1) and wide linear concentration ranges (1 × 10-15-1 × 10-8g ml-1) when a potential of 170 mV versus Ag/AgCl was applied. This allowed for the molecular identification and quantification of HER3 and HER4 in patients with gastric cancer, as well as in healthy individuals.

Correlation between Maspin Levels in Different Biological Samples and Pathologic Features in Colorectal Adenocarcinomas.

Maspin is an important biomarker which was proven to be correlated to many pathological features that can help the oncologists, the surgeons and also the pathologists for choosing the personalized treatment of the patients. Maspin expression correlates with the budding of colorectal adenocarcinomas that is usually used mostly in immunohistochemistry. In this preliminary study, a small number of patients with clinical and pathological features were selected. Four kinds of samples (tumoral tissues, blood, saliva and urine) were analyzed using a stochastic method using stochastic microsensors. Whole blood maspin concentration values were related to budding, molecular subtype and location. Tissular maspin concentrations were related to location, maxi-mum diameter and pN value from TNM staging system. Salivary maspin concentrations were related to budding, mucinous compound and macroscopic features. Urinary maspin concentrations were related to pT value from TNM staging system, budding and molecular subtype. The correlations made in this paper may be used for fast diagnostic of colorectal adenocarcinomas, after which, it will be tested on a significant number of patients confirmed with colon cancer, in different stages of evolution.

Extraction of heavy metals by cooking/preserving of seafood, tuna and poultry from Romania - A source of contamination with heavy metals.

The study aims to provide evidence regarding the impact of the extraction of heavy metals into food products through conventional cooking and preserving of foods like seafood, tuna, and poultry. The optical emission spectrometric technique with an inductively coupled plasma source (ICP-OES) was employed to determine trace levels of heavy metals in the muscle tissue of seafood, fish meat, tuna species, poultry, and turkey that was collected raw, cooked, frozen, and preserved. Conventional cooking increased the concentration of some heavy metals (Al, Sn, Fe, Co, Ti, and Mn) by more than 100.00%, while preserving the mussels promoted the extraction and accumulation of metals such as Al, Fe, Sn, Zn, Cu, Hg, and As, resulting in an increase in concentration of more than 180.00%.

Simultaneous determination of anthracene and phenanthrene using a poly-alizarin red S/carbon paste electrode.

A polymer-based carbon paste electrode was constructed by electropolymerized Alizarin Red S (ARS) film on the carbon paste electrode (CPE) surface. The electrochemical properties of poly-ARS/CPE were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Scanning electron microscopy (SEM) was utilized for electrode characterization. The electropolymerization cycles for the construction of the sensor and the supporting electrolyte were optimized. With 0.1 M LiClO4 as a supporting electrolyte, poly-ARS/CPE was able to generate oxidation peaks for anthracene (ANT) and phenanthrene (PHE), that were clearly defined and easily distinguished from one to another when operating in square wave voltammetry (SWV). In the simultaneous detection the linear ranges of ANT and PHE were within 80-1000 µM, with detection limits of 24 µM. The variation of peak parameters with scan rate was investigated to determine the nature of electrooxidation and the number of electrons involved in the electrode process. Poly-ARS/CPE was successfully utilized for the detection of ANT and PHE in different water samples and the obtained results suggested the selectivity, stability and reproducibility of the modified electrode.

Molecular Recognition and Quantification of HER-3, HER-4 and HRG-α in Whole Blood and Tissue Samples Using Stochastic Sensors.

Human epidermal growth factor receptor-3, human epidermal growth factor-receptor-4, and heregulin-α are some of the biomarkers related to gastric cancer currently being used for early detection, personalized treatment, and evaluation of the efficiency of the treatment. Two stochastic sensors based on graphene decorated with TiO2 and/or Au modified with maltodextrin were proposed for the screening of two types of whole blood and tissue samples for the simultaneous recognition and analysis of the three biomarkers. The sensitivity of the two sensors showed high values, whereas the limits of determination were of fg mL-1 magnitude order. Thus, the proposed screening method can perform the quantitative analysis of both of the biomarkers of interest in whole blood and tissue samples, with recoveries higher than 96.00% and relative standard deviations lower than 1.00%.

Carbon Nanopowder-Based Stochastic Sensor for Ultrasensitive Assay of CA 15-3, CEA and HER2 in Whole Blood.

Two microsensors obtained by the physical immobilization of 5,10,15,20-tetraphenyl-21H,23H-porphine (TPP) and 5,10,15,20-tetrakis (pentafluorophenyl chloride)-21H,23H-iron (III) porphyrin (Fe(TPFPP)Cl) in carbon nanopowder decorated with gold nanoparticles (AuNp) were designed, characterized, validated and used for the molecular recognition and simultaneous ultrasensitive determination of CEA, CA15-3 and HER2 in whole blood. High sensitivities were recorded for both microsensors. Low limits of quantification were recorded for all biomarkers: CEA (12.8 pg mL-1 by using Fe(TPFPP)Cl/AuNp, and 190 fg mL-1 by using TPP/AuNp), CA 15-3 (100 fU mL-1 for both microsensors) and HER2 (3.9 fg mL-1 by using Fe(TPFPP)Cl/AuNp, and 35 fg mL-1 by using TPP/AuNp). A very good correlation between the results obtained using the proposed microsensors and ELISA, certified by the Student t-test, proves that the screening test can be used for ultrasensitive assays of the three biomarkers in whole blood.

V-set and immunoglobulin domain containing 1 (VSIG1) as an emerging target for epithelial-mesenchymal transition of gastric cancer.

V-set and Immunoglobulin domain containing 1 (VSIG1) is a cell-cell adhesion molecule which role in the genesis and evolution of gastric cancer (GC) is not understood. Only three Medline-indexed papers have focused on the role of VSIG1 in GC. The clinicopathological features of 94 GCs were examined in association with immunohistochemical (IHC) patterns of VSIG1, E-cadherin, and ß-catenin which were assessed in the tumor core (central) vs. invasive edge. Cases were classified depending on the VSIG1 expression: membrane/membrane in both core and invasive front; null/negative staining in both core and invasive front; and cases with translocational patterns: membrane core/cytoplasmic buds and cytoplasmic core/null buds. Most of the tumors showed null pattern (n = 54). Cases with translocational patterns (n = 20) were GCs with a high lymph node ratio value (≥ 0.26) and advanced Dukes-MAC-like stage. Of the 20 total cases, 9 showed membrane-to-nuclear translocation of ß-catenin and loss of E-cadherin, as indicators of epithelial-mesenchymal transition. All cases with membrane/membrane pattern (n = 20) involved the distal stomach. The poorest overall survival was registered in patients with subcellular translocation of VSIG1, compared to those with either membrane/membrane or null patterns (p = 0.002). In GC, VSIG1 acts as an adhesion membrane protein but its membrane-cytoplasmic translocation can be an indicator of epithelial-mesenchymal transition due to cytoplasmic VSIG1-mediated activation of canonical Wnt/ß-catenin signaling pathway.

Sulfur-Doped Graphene-Based Electrochemical Sensors for Fast and Sensitive Determination of (R)-(+)-Limonene from Beverages.

Two sensors based on sulfur-doped graphene, a gold nanoparticle paste modified with 5,10,15,20-tetraphenyl-21H,23H-porphine and 5,10,15,20-tetrakis (pentafluorophenyl chloride)-21H,23H-iron (III) porphyrin, were proposed for the determination of R-limonene in beverages (triple sec liqueur and limoncello). Differential pulse voltammetry was the method used to characterize and validate the proposed sensors. The response characteristics showed that the detection limits for both sensors were 3 × 10-6 mol L-1, while the quantification limits were 1 × 10-5 mol L-1. Both sensors can be used to determine R-limonene in a concentration range between 1 × 10-5-6 × 10-4 mol L-1 for TPP/AuNPs-S-Gr and 1 × 10-5-1 × 10-3 mol L-1 for Fe(TPFPP)Cl/AuNPs-S-Gr. The highest sensitivity (0.7068 µA/mol L-1) was recorded when the TPP/AuNPs-S-Gr sensor was used, proving that the electrocatalytic effect of this electrocatalyst is higher compared to that of Fe(TPFPP)Cl/AuNPs-S-Gr. High recoveries (values greater than 99.00%) and low RSD values (%) (below 5.00%) were recorded for both sensors when used to determine R-limonene in triple sec liqueur and limoncello.

Highly Sensitive Electrochemical Detection of Azithromycin with Graphene-Modified Electrode.

An electrochemical cell containing two graphite rods was filled with the appropriate electrolyte (0.2 M ammonia + 0.2 M ammonium sulphate) and connected to the exfoliation system to synthesize graphene (EGr). A bias of 7 V was applied between the anode and cathode for 3 h. After synthesis, the morphology and structure of the sample was characterized by SEM, XRD, and FTIR techniques. The material was deposited onto the surface of a glassy carbon (GC) electrode (EGr/GC) and employed for the electrochemical detection of azithromycin (AZT). The DPV signals recorded in pH 5 acetate containing 6 × 10-5 M AZT revealed significant differences between the GC and EGr/GC electrodes. For EGr/GC, the oxidation peak was higher and appeared at lower potential (+1.12 V) compared with that of bare GC (+1.35 V). The linear range for AZT obtained with the EGr/GC electrode was very wide, 10-8-10-5 M, the sensitivity was 0.68 A/M, and the detection limit was 3.03 × 10-9 M. It is important to mention that the sensitivity of EGr/GC was three times higher than that of bare GC (0.23 A/M), proving the advantages of using graphene-modified electrodes in the electrochemical detection of AZT.