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.

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.

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.

Disposable stochastic sensors obtained by nanolayer deposition of copper, graphene, and copper-graphene composite on silk for the determination of isocitrate dehydrogenases 1 and 2.

Three disposable stochastic sensors designed using nanolayer deposition of copper (Cu), graphene (GR), and copper-graphene (Cu-GR) composite on the silk textile, as substrate, were modified with chitosan (n=371-744), for biomedical analysis. Isocitrate dehydrogenase 1 (IDH1) and isocitrate dehydrogenase 2 (IDH2) served as model analytes for molecular recognition and quantification in biological samples such as whole blood and brain tumor tissue samples. The best sensitivities (3.77×107s µg mL-1 for IDH1, and 1.88×107s µg mL-1 for IDH2) and the lowest limits of quantification (10-2fg mL-1 for IDH1, and 5×10-2fg mL-1 for IDH2) for both IDH1 and IDH2 were recorded for the disposable stochastic sensors based on chitosan/graphene nanolayer. Very good correlations between the screening method based on disposable stochastic sensors and enzyme-linked immunosorbent assay (ELISA) were obtained; this was also proved by the results obtained using the paired t-test.

Nanographene-based electrochemical sensors for ultrasensitive determination of sorbic acid from food.

Ultrasensitive determination of sorbic acid in food is essential for the assessment of the food quality. Therefore, two sensors based on nanographene decorated with gold nanoparticle paste modified with metal porphyrins (Zn protoporphyrin IX, and 2,3,7,8,12,13,17,18 octaethyl, 21H, 23H-porphirine Mn(III) chloride) were proposed for the determination of sorbic acid in food (bakery products and mayonnaise). Square-wave voltammetry was used for the characterization and validation of the proposed sensors. Response characteristics showed that the limits of detection for both sensors were 0.33 µmol L-1 while the limits of quantification were 1.00 µmol L-1. Both sensors can be used for the determination of sorbic acid in the concentration range 1-1000 µmol L-1, the linear concentration range making them appropriate for the assay of sorbic acid in food. The highest sensitivity (0.35 nA/µmol L-1) was recorded when the sensor based on 2,3,7,8,12,13,17,18 octaethyl, 21H, 23H-porphirine Mn(III) chloride was used, proving the higher electrocatalytic effect of this electrocatalyst versus the one of the Zn protoporphyrin IX. High recoveries (values higher than 95.00%) and low RSD (%) values (lower than 5.00%) were recorded for both sensors when used for the determination of sorbic acid in bread and mayonnaise, proving the high reliability of the proposed sensors and method.

Stochastic microsensors based on modified graphene for pattern recognition of maspin in biological samples.

Maspin is a novel serine protease inhibitor differentially expressed in several types of human cancers. It proved to be a key biomarker in the assessment of gastric cancer. Therefore, we design, characterize, and validate two stochastic microsensors based on graphene co-doped with N and S, and modified with α-cyclodextrin and maltodextrin, for the pattern recognition and quantification of maspin in whole blood, gastric tumor tissue, saliva, and urine. While the sensitivities were comparable with magnitude order, the variations were in the wideness of the linear concentration range, when measurements were performed at a pH of 7.40. Very low limits of quantification were recorded at both working pHs: 7.40, and 3.00. High recoveries of maspin in whole blood, gastric tissue tumor, saliva, and urine were also recorded.

N,S-Decorated graphenes modified with 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphine manganese(III) chloride-based 3D needle stochastic sensors for enantioanalysis of arginine: a key factor in the metabolomics and early detection of gastric cancer.

Arginine has an important role in the metabolomics of gastric cancer. Two 3D enantioselective needle stochastic sensors based on the physical immobilization of 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphine manganese(III) chloride (solution, 10-3 mol L-1) in graphene paste matrices decorated with N and S atoms were designed, characterized and validated for the enantioanalysis of arginine in whole blood and tissue samples. The signature values obtained for the enantiomers of arginine confirmed that the stochastic sensors are enantioselective. The lowest limit of quantification obtained for both enantiomers of arginine was 1 fmol L-1, while sensitivity of up to 1011 s-1 mol-1 L was recorded for the stochastic sensors. High recoveries were obtained for the determination of one enantiomer in the presence of the other one; moreover, very good correlation was found between the results obtained with the two 3D enantioselective needle stochastic sensors.

2D disposable stochastic sensors for molecular recognition and quantification of maspin in biological samples.

Three disposable stochastic sensors using nanolayer deposition of a graphene nanocomposite comprising graphene nanoparticles and gold nanoparticles, on different supports: silk, plastic, and paper, and modified with chitosan, were characterized and validated for molecular recognition and quantification of maspin in biological samples. Very low limits of determination (of pg mL-1 magnitude order) were recorded (5.12 pg mL-1 for the sensor based on silk at pH 7.40 and on copy paper at pHs 3.00 and 7.40; 16 ng mL-1 at pH 7.40 for the sensor based on plastic, 41.00 pg mL-1 for the sensor based on silk at pH 3.00, and 204.00 pg mL-1 for the sensor based on plastic, at pH 3.00), with wide linear concentration ranges (5.12 × 10-12-2.00 × 10-6 g mL-1 for the sensors based on silk at pH 7.40, and on copy paper at pH 3.00; 5.12 × 10-12-8.00 × 10-7 g mL-1 for the sensor based on copy paper at pH 7.40; 1.60 × 10-8-2.00 × 10-6 g mL-1 for the sensor based on plastic at pH 7.40; 4.10 × 10-14-2.00 × 10-6 g mL-1 for the sensor based on silk, at pH 3.00; and 2.04 × 10-13-8.00 × 10-7 g mL-1 for the sensor based on plastic at pH 3.00) allowing the molecular recognition and quantification of maspin in healthy people and patients with gastric cancer, when a potential of 125 mV vs. Ag/AgCl was applied. The recoveries of maspin in whole blood, saliva, urine, and tissue samples were higher than 95.00%, with a relative standard deviation lower than 1.0%.

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.

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.

Gold Nanoparticles/Nanographene-Based 3D Sensors Integrated in Mini-Platforms for Thiamine Detection.

Vitamins are essential for sustaining daily activities and perform crucial roles in metabolism, such as preventing vascular events and delaying the development of diabetic nephropathy. The ultrasensitive assessment of thiamine in foods is required for food quality evaluation. A mini-platform utilizing two 3D sensors based on nanographene and gold nanoparticles paste modified with protoporphyrin IX and protoporphyrin IX cobalt chloride is proposed for the detection of thiamine in blueberry syrup, multivitamin tablets, water, and a biological sample (urine). Differential pulse voltammetry was utilized for the characterization and validation of the suggested sensors. The sensor modified with protoporphyrin IX has a detection limit of 3.0 × 10-13 mol L-1 and a quantification limit of 1.0 × 10-12 mol L-1, whereas the sensor modified with protoporphyrin IX cobalt chloride has detection and quantification limits of 3.0 × 10-12 and 1.0 × 10-11 mol L-1, respectively. High recoveries (values greater than 95.00%) and low RSD (%) values (less than 5.00%) are recorded for both 3D sensors when used for the determination of thiamine in blueberry syrup, multivitamin tablets, water, and urine, demonstrating the 3D sensors' and suggested method's high reliability.

Smart Portable Device Based on the Utilization of a 2D Disposable Paper Stochastic Sensor for Fast Ultrasensitive Screening of Food Samples for Bisphenols.

Since the determination of the high toxicity of bisphenol A, alternative structures for bisphenols have been synthesized, resulting in bisphenols C, E, F, S, and Z. These bisphenols have replaced bisphenol A in plastic bottles, toys, and cans used for preserving food. Later, the toxicity and negative effects of all of these bisphenols on people's health were proven. Therefore, there is a need for a fast ultrasensitive screening method that is able to detect the presence of these bisphenols in any condition directly from food samples. This paper presented a disposable device based on the utilization of a 2D disposable paper stochastic sensor for the fast ultrasensitive screening of food samples for bisphenols A, C, E, F, S, and Z. The 2D disposable sensor was obtained by the deposition of graphene and silver nanolayers on paper using cold plasma. Furthermore, the active side of the sensor was modified using 2,3,7,8,12,13,17,18-octaethyl-21H,23H Mn porphyrin. The limits of quantification of these bisphenols were 1 fmol L-1 for bisphenols C and E, 10 fmol L-1 for bisphenols A and F, 10 pmol L-1 for bisphenol S, and 1 pmol L-1 for bisphenol Z. The recoveries of these bisphenols in milk, canned fruits, vegetables, and fish were higher than 99.00% with RSD (%) values lower than 1.50%.

3D stochastic microsensors for molecular recognition and determination of heregulin-α in biological samples.

Two 3D stochastic microsensors based on single and multi-walled carbon nanotubes modified with 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphine manganese (III) chloride were proposed for the molecular recognition and determination of heregulin-α, in whole blood samples and tumour brain tissues. The proposed 3D stochastic sensors had limits of determinations of 102 fg mL-1 and high sensitivities. The linear concentration ranges of the two 3D stochastic microsensors covered the healthy people as well as the patients confirmed with brain cancer. Determination of heregulin-α was done in whole blood and tissue samples using the screening method based on the proposed 3D stochastic microsensors as well as using the ELISA method; very good correlations were obtained between the two methods proving that the proposed method can be used in screening tests of whole blood and tumoural tissue samples for molecular recognition and determination of heregulin-α.

Chiral single-walled carbon nanotubes as chiral selectors in multimode enantioselective sensors.

Single-walled carbon nanotube-(7,6) chirality was used for the design of multimode enantioselective sensors using different carbon matrices such as graphene paste, graphite paste, and carbon nanopowder-based paste. l- and d-malic acids were used as model analytes. The responses of the multimode sensors were evaluated for potentiometric and differential pulse voltammetry (DPV) modes. When carbon nanopowder was used as matrix, the multimode sensor was enantioselective for d-malic acid in the concentration range 10-3 to 10-15 mol/L for the potentiometric mode and 10-5 to 10-8 mol/L for the DPV mode. The graphite paste-based sensor was enantioselective for l-malic acid in the ranges: 10-10 to 10-13 for the potentiometric mode and 10-4 to 10-7 mol/L for the DPV mode. The sensors based on graphene and chiral single-walled carbon nanotubes were enantioselective for d-malic acid, and a response was obtained only in the DPV mode. Accordingly, the matrix influenced both the enantioselectivity and the sensitivity of the measurements. The application of the sensors was for the enantioanalysis of malic acid in wines and apple juice samples. The proposed method is fast and reliable and allows the quantification of l- and d-malic acids using electrochemical methods based on different principles, from the real samples after a buffering of the samples. The enantioanalysis of malic acid in wine and juice samples was performed with high recoveries (higher than 90.00%) and low relative standard deviation (RSD) (%) values (lower than 1.00%).

Mussel Shells, a Valuable Calcium Resource for the Pharmaceutical Industry.

(1) Background: The mussel (Mytilus edulis, Mytilus galloprovincialis) is the most widespread lamellibranch mollusk, being fished on all coasts of the European seas. Mussels are also widely grown in Japan, China, and Spain, especially for food purposes. This paper shows an original technique for mussel shell processing for preparation of calcium salts, such as calcium levulinate. This process involves synthesis of calcium levulinate by treatment of Mytilus galloprovincialis shells with levulinic acid. The advantage of mussel shell utilization results in more straightforward qualitative composition. Thus, the weight of the mineral component lies with calcium carbonate, which can be used for extraction of pharmaceutical preparations. (2) Methods: Shell powder was first deproteinized by calcination, then the mineral part was treated with levulinic acid. The problem of shells generally resulting from the industrialization of marine molluscs creates enough shortcomings, if one only mentions storage and handling. One of the solutions proposed by us is the capitalization of calcium from shells in the pharmaceutical industry. (3) Results: The toxicity of calcium levulinate synthesized from the mussel shells was evaluated by the method known in the scientific literature as the Constantinescu phytobiological method (using wheat kernels, Triticum vulgare Mill). Acute toxicity of calcium levulinate was evaluated; the experiments showed the low toxicity of calcium levulinate. (4) Conclusion: The experimental results highlighted calcium as the predominant element in the composition of mussel shells, which strengthens the argument of capitalizing the shells as an important natural source of calcium.

Hydrothermal Synthesis of Nitrogen, Boron Co-Doped Graphene with Enhanced Electro-Catalytic Activity for Cymoxanil Detection.

A sample of nitrogen and boron co-doped graphene (NB-Gr) was obtained by the hydrothermal method using urea and boric acid as doping sources. According to XRD analysis, the NB-Gr sample was formed by five-layer graphene. In addition, the XPS analysis confirmed the nitrogen and boron co-doping of the graphene sample. After synthesis, the investigation of the electro-catalytic properties of the bare (GC) and graphene-modified electrode (NB-Gr/GC) towards cymoxanil detection (CYM) was performed. Significant differences between the two electrodes were noticed. In the first case (GC) the peak current modulus was small (1.12 × 10-5 A) and appeared in the region of negative potentials (-0.9 V). In contrast, when NB-Gr was present on top of the GC electrode it promoted the transfer of electrons, leading to a large peak current increase (1.65 × 10-5 A) and a positive shift of the peak potential (-0.75 V). The NB-Gr/GC electrode was also tested for its ability to detect cymoxanil from a commercial fungicide (CURZATE MANOX) by the standard addition method, giving a recovery of 99%.

Stochastic microsensors for the assessment of DNA damage in cancer.

Three stochastic microsensors based on graphite powder modified with three different oleamides: N-(2-piperidin-1-ylethyl)oleamide, N-(3,4-dihydroxyphenethyl)oleamide and N-(2-morpholinoethyl)oleamide, were designed, characterized, and used to assess DNA damage in cancer by assaying two biomarkers namely 8-nitroguanine and 8-hydroxy-2'-deoxyguanosine. The two biomarkers were determined from urine and whole blood samples. The characterization of the microsensors was done at two pHs 7.40 and 3.00. The best microsensor for the simultaneous determination of biomarkers in whole blood and urine samples was the one based on the graphite paste modified with N-(3,4-dihydroxyphenethyl)oleamide. The results indicated that the proposed microsensors can be reliably used for pattern recognition and quantitative determination of 8-nitroguanine and 8-hydroxy-2'-deoxyguanosine in whole blood and urine, and accordingly, for the assessment of DNA damage in cancer patients.

Fast screening method for molecular recognition of islet amyloid polypeptide from whole blood samples collected from diabetic patients with disposable stochastic sensors obtained by nanolayer, and nanolayer by nanolayer deposition using cold plasma.

Nanolayer and nanolayer by nanolayer deposition of nanofilms of Ag and C using cold plasma in sequences (Ag, Ag-C, Ag-Ag-C), on porous paper, were used to design three disposable stochastic sensors for the assay of amyloid polypeptide from whole blood. The nanofilms were modified with α-cyclodextrin. The test developed using the nanofilm-based disposable stochastic sensors is used for early detection of diabetes. The wider linear concentration range (1.00 × 10-6-1.00 ng mL-1) and the lower limit of quantification (1.00 × 10-6ng mL-1) were obtained using the disposable stochastic sensors based on Ag-C and Ag-Ag-C, while the highest sensitivity (3.19 × 104 s-1/µg mL-1) was recorded using the disposable stochastic sensor based on Ag-Ag-C. The screening methods were fully validated using whole blood samples from confirmed patients, when the recovery of the islet amyloid polypeptide was higher than 98.00%. Graphical abstract.

Enantioanalysis of glutamine-a key factor in establishing the metabolomics process in gastric cancer.

Gastric cancer is the second leading cause of death in the world. Early detection will facilitate early treatment and full recovery of the patients. Metabolomics facilitated the detection of few amino acids able to be used as biomarkers. It was always assumed that the L-enantiomer of the chiral amino acid is part of the process, forgetting the twisting of DNA molecules which may also produce the D-enantiomer of the amino acid. Therefore, an enantioanalysis of amino acids such as glutamine which are part of the gastric cancer metabolomics is absolutely necessary. Four stochastic sensors based on immobilization of protoporphyrin IX, ß-cyclodextrin, and 2,2-diphenyl-1-picrylhydrazyl on graphene materials were proposed for the enantioanalysis of glutamine in whole blood samples of patients with gastric cancer. Different signatures were obtained for the enantiomers for each stochastic sensor, making possible the enantioanalysis of glutamine in large concentration ranges-from fmol/L to mmol/L; these ranges facilitating the enantioanalysis of glutamine in healthy patients as well as in patients were found in early and later stages of gastric cancer. Graphical abstract.

Myoglobin-silver reduced graphene oxide nanocomposite stochastic biosensor for the determination of luteinizing hormone and follicle-stimulating hormone from saliva samples.

A silver reduced graphene oxide (Ag-rGO) nanocomposite paste was prepared for the assay of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in children's saliva. The paste was modified with a solution of myoglobin (Myb) to form the stochastic biosensor, to improve the sensitivity of the method. The Ag-rGO powder and Myb-Ag-rGO paste were morphologically and structurally characterized by SEM, TEM and XRD measurements. For the molecular recognition of the hormones, the biosensor based on Myb-Ag-rGO reached determination limits of 8.5 × 10-3 UI L-1 (2.0 × 10-12 g/mL) for luteinizing hormone and 1.4 × 10-2 UI L-1 (1.0 × 10-12 g/mL) for follicle-stimulating hormone. The determination of both hormones in saliva samples collected from children was done with high reliability. Graphical Abstract.