Limit Of Detection LOD Research Articles

Decoration of recycled battery graphite functionalized with gold nanoparticles/poly(nicotinic acid) for detection of bifenazate pesticide in tea and food samples

Bifenazate (BF), is a type of carbamate acaricide effective at controlling mite parasites on crops and ornamental plants. In this work, a recycled dry zinc-carbon battery graphite electrode decorated with gold nano particles/poly nicotinic acid, AuNPs/poly(NA)-BGE, was applied as the working electrode for the electrochemical measurement of bifenazate (BF). The working electrode (BGE) was functionalized by 10 electropolymerization voltammetric cycles of poly nicotinic acid poly (NA) following by 30 s of amperometric deposition of gold nanoparticles (AuNPs) to produce the final AuNPs/poly(NA)-BGE electrode in a two-step procedure. “Electrochemical and morphological characterization of the sensor at its different production steps was performed using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive X-ray spectroscopy (EDX) techniques and Transmission electron microscopy (TEM).” The highest peak current response was attained using pH 6.0 in 0.1 M phosphate buffer. The sensor exhibited a linearity range from (1 × 10−4–1 × 10−8 M) that is equivalent to 30.035–3.00 × 10−3 µg/mL with limits of detection LOD and quantification 3.3 × 10−11 M (9.91 × 10−6 µg/mL) and 1.00 × 10−10 M (3.00 × 10−5 µg/mL), respectively. Finally, with a recovery range of (96.3 %–102.6 %) and an RSD of (0.17 %–0.64 %), BF in Kenyan green and black tea, strawberry, tomato, cucumber and its commercial formulation Duramite® 24 %SC was successfully quantified which indicates the promising applicability of the presented sensor in different matrixes.

Dried blood spot (DBS) analysis of synthetic cathinones by different liquid chromatography-mass spectrometry techniques and interlaboratory validation for application in forensic toxicology

Dried Blood Spot (DBS) technique was employed as sample pretreatment for the detection of synthetic cathinones in blood samples, including from postmortem caseworks, by Liquid Chromatography-tandem Mass spectrometry (LC-MS/MS) techniques. The study involved the interlaboratory validation to evaluate the applicability of the method with different instruments, to assess the applicability and the ruggedness of the method for its wide application. The stability of cathinones in DBS was also evaluated.Authentic casework from drug-related deaths (DRD) involving synthetic cathinones were analysed and results compared in the two laboratories, using the developed methods. Metabolites were studied by two different LC-HRMS methods, orbitrap and Q-TOF.Validation results obtained in both laboratories demonstrated the suitability of DBS as sample storage and pre-treatment technique, allowing good sensitivities, repeatability, matrix effect and %bias. Limits of detection LOD and of quantification LOQ ranged between 0.3 and 1 ng/ml and between 0.5 and 10 ng/mL, respectively, for the studied cathinones in both laboratories. Stability studies demonstrated the high percent of degradation of cathinones, depending on their molecular structure, not attributable to DBS. The analysis of forensic caseworks containing α-PHP and MDPHP by DBS allowed their identification and quantification and the detection of various metabolites in postmortem blood samples. α-PHP degraded over time, while MDPHP concentration did not show significant differences in a three-months period, probably due to the presence of the metylendioxy moiety.These results demonstrate DBS to be a rapid and efficient technique for the analysis of cathinones, and that quantitative results for these analytes should be carefully interpreted due to their possible degradation.

Development and Validation of RP-HPLC Method for Estimation of Winter green Oil in Pharmaceutical Formulation

Background Wintergreen oil WO is used in various applications including aromatherapy and in topical pain relief products. The main active compound in wintergreen oil is methyl salicylate which is related to salicylic acid a component found in aspirin.Aim To develop and validate the RP-HPLC method for quantifying WO using methyl salicylate as the reference standard.Method In this study the pharmaceutical formulation chosen were nanosponges. A Gemini NX C18 250 mm X 4.6 mm 5 m column was used for the chromatographic separation carried out at room temperature with UV detection at 268 nm. A 1.5 mL min-1 flow rate was employed for the mobile phase which was a 5050 vv combination of acetonitrile and water. As per ICH requirements the approach was validated.Results The created technique showed R2 value of 0.9983 and exhibited linearity over 300-1500 microgmL concentration range. It was discovered that the limit of detection LOD and the limit of quantification LOQ levels were 0.082 microgmL and 0.25 microgmL respectively. The RSD values for repeatability intermediate and method precision were found to be within the limits of 2. The recovery ranged between 100.4 to 100.8 and negligible variations in RT and peak area with deliberate variations in pH flow rate wavelength and mobile phase ratio indicated robustness. The entrapment efficiency and loading capacity of nanosponges were determined to be 73.7-97.4 and 6.85-0.07 respectively.Conclusion The proposed method was proven to be particular straightforward sensitive precise and adaptable. As a result the technique was successfully utilized to estimate wintergreen oil in pharmaceutical formulations.

A-116 Evaluation of Lp(a) Ultra assay for the Immunoturbidimetric Quantitative Determination of Lipoprotein (a) in Human Serum and Plasma With Siemens Healthineers Atellica CH 930 Analyzer

Abstract Objective The aim of this study is to evaluate the analytical performances of the Lp(a) Ultra assay for the immunoturbidimetric quantitative determination of lipoprotein (a) in human serum and plasma on Siemens Healthineers Atellica CH 930 Analyzer. Background Lipoprotein (a) has been found in artery walls and can have atherogenic effects. Because of its structural similarity to plasminogen, it can also inhibit fibrinolysis and hence acts thrombogenically. High Lp(a) concentrations in serum correlate with premature manifestation of atherosclerosis and strokes. In combination with elevated LDL Cholesterol concentrations, the coronary risk increases approximately six-fold. Methods Lp(a) Ultra is a latex immunoassay manufactured by Sentinel Diagnostics and developed to measure Lp(a) levels. If the antigen-antibody reaction takes place between Lp(a) in the sample and the anti-Lp(a) antibodies, which have been adsorbed to latex particles, agglutination occurs. This agglutination is detected as an absorbance change, with the magnitude of the change being proportional to the quantity of Lp(a) contained in the sample. Results The Limit of Blank LOB (4 samples × 5 replicates × 3 runs) was ≤2.0 mg/dL. The Limit of Detection LOD (4 samples × 5 replicates × 3 runs) was ≤ 3.0 mg/dL. The Limit of Quantitation LOQ (8 dilution levels × 10 replicates × 3 runs) was ≤5.0 mg/dL at %CV lower than 20%. The Intra Assay (5 samples × 20 replicates × 3 runs) gave the following %CVs: 2.4% at 12.1 mg/dL, 0.8% at 30.3 mg/dL, 0.6% at 47.8 mg/dL, 0.5% at 58.8 mg/dL, 1.7% at 87.1 mg/dL. Total precision study (5 samples × 2 runs × 2 replicates × 20 runs) gave the following %CVs: 4.0% at 11.5 mg/dL, 3.6% at 21.7 mg/dL, 3.0% at 32.0 mg/dL, 2.8% at 42.2 mg/dL, 2.3% at 50.7 mg/dL. The test was linear up to 130 mg/dL. Calibration stability was up to 30 days. Reagent on board stability was up to 30 days. This application (y) was compared with the same test applied on Beckman Coulter AU680 Analyzer (x) and gave the following results: using Passing Bablok analysis: y = 0.8 + 1.0x; correlation coefficient (r) = 0.997; using Deming analysis: y = 1.0 + 1.0x; correlation coefficient (r) = 0.997; number of samples = 120. There is not Hook effect/antigen excess up to 600 mg/dL. Conclusions Analytical performances of Lp(a) Ultra assay on Siemens Healthineers Atellica CH 930 Analyzer meet the requirements for its use as immunoturbidimetric quantitative determination of lipoprotein (a) in human serum and plasma and make this assay very suitable for the routine measurement of this analyte.

Simple excited state intramolecular proton transfer (ESIPT) based probe for pH and selective detection of copper(II) ion in aqueous alkaline environment: Sensitivity, selectivity and logic behavior

A low molecular weight ESIPT-based probe was synthesized and tested for detecting pH, cations, and anions in aqueous solutions. The probe exhibited a good emission in water due to aggregation induced by π-π* stacking. It gave an “off–on” fluorescent response to higher pHs because of blocking the non-radiative ESIPT after deprotonating phenolic hydroxyl groups. Moreover, the fluorescence emission of the probe (water/ethanol = 3:1, pH 10) was quenched only by Cu2+ with limit of detection LOD = 3.2 μM. The stoichiometric ratio of the probe/Cu2+ complex was found to be 1:1. Furthermore, changes of the probe’s absorption and emission signals (as outputs) in response to the presence of H+ and HO– or Cu2+ and Br− stimuli (as chemical inputs) mimics INHIBIT, IMPLICATION and NOT TRANSFER logic gates.

Naphthalene-based silica nanoparticles as a highly sensitive fluorescent chemosensor for mercury detection in real seawater

Mercury is considered one of the most harmful contaminants threatening human lives and the aquatic environment. Naphthalene and its derivatives have excellent fluorescence properties that can be exploited for mercury (Hg2+) sensing applications. Herein, we covalently attached naphthalene with silica nanoparticles (NSPs) using one-pot multiple steps synthesis approach. The NSPs were characterized by 1H NMR, FTIR, TGA, FESEM, and UV–vis spectroscopy. The fluorescent properties were analyzed in deionized water under normal and UV-light illumination. Finally, the synthesized NSPs were investigated as a chemosensor for Hg2+ ions detection in real seawater samples via photoluminescence (PL) spectroscopy. The results indicate that the fluorescence properties of NSPs (20 ppm) were quenched upon Hg2+ addition in the range from 0 to 50 ppm. The studies demonstrated that NSPs acted as a potential host for Hg2+ ions compared to other interfering ions present in the seawater sample. The NSPs chemosensor provides a linearity range (5 – 1000 ppb) and limit of detection LOD (1 ppb; 5 nM), even below the values suggested by US EPA drinking water safety regulations, which indicates its potential utilization for mercury sensing in seawater environments.

VALIDATION OF THE METHOD FOR THE DETERMINATION OF RARE EARTH METALS IN BIOLOGICAL SAMPLES BY THE ATOMIC EMISSION INDUCTIVELY COUPLED PLASMA METHOD (ICP OES)

Currently, one of the priority nanomaterials are nanoparticles of rare earth metals (RЕM) – cerium, lanthanum, gadolinium and others, which allows them to be successfully used as new natural feed additives (due to their antimicrobial and antioxidant properties) in order to increase the productivity of animals. However, the issue of redistribution in the body and accumulation of RЕMs in livestock products requires an adequate answer using sensitive and highly accurate quantitative research methods, in connection with which the determination of RЕMs in biological samples becomes extremely relevant. Within the framework of this study, the suitability assessment (validation) of the developed method for the determination of RЕM (lanthanum and gadolinium) in biological samples (serum, liver, kidneys) using atomic emission inductively coupled plasma (ICP OES) was carried out and the method of sample preparation in various matrices was adapted. Key working parameters were determined as evaluation criteria: limit of detection, limit of quantification, accuracy, correctness, convergence, reproducibility, selectivity, linearity, working range. It was established that this method demonstrates good linearity in the working range of 1.0-500.0 μg/kg(dm3) for Gadolinium and 0.5-500.0 μg/kg(dm3) for Lanthanum; the method is selective, sensitive, practical and accurate. The limit of detection LOD and limit of quantification LOQ for Gadolinium and Lanthanum are 0.1 and 0.05 μg/kg(dm3) and 1.0 and 0.5 μg/kg(dm3), respectively. The validation data obtained meet the requirements of the Eurachem Guideline and the IUPAC Harmonized Guideline for Single-Laboratory Validation, and the method for the determination of RЕMs in biological samples is suitable for a specific application according to ISO/IEC 17025:2019.

Indirect spectroscopic determination of esomeprazole using malachite green dye in the presence of N-bromosuccinimide

A simple, fast and sensitive spectrophotometric method has been developed for the determination of esomeprazole in its pure form and also in the form of a pharmaceutical preparation. The highest absorption was found at a wavelength of 618 nm and the limits of Beer were (2_24) µg/ml. The molar absorbance (2.1070 ˣ104) L.mol-1 .cm-1, Sandell sensitivity 0.016 µg.cm-2, and limits of detection LOD 0.0153 µg/ml, LOQ 0.0510 µg/ml were determined the method was also applied to pharmaceutical preparations, and the validity of the method was confirmed by standard addition.

Spectrophotometric estimation of esomeprazole using diazotization reaction with meta- amino phenol reagent and application in pharmaceutical preparations

The aim of the following study is to develop a sensitive, high-accuracy and fast spectrophotometric method for the determination of esomeprazole (ESO) in pharmaceutical preparations.The proposed method is based on the formation of dyzonium salt from the reaction of meta-aminophenol reagent with nitrite in an acidic medium and then coupling it with esomeprazole in an alkaline medium to form a yellow dye that gives the highest absorption at a wavelength of 450 nm. Obtaining a calibration curve within 1_12 with a correlation coefficient of 0. 999. The molar absorbance 3.3954 × 104 L.mol-1 .cm-1, Sandell sensitivity 0.0101 µg.cm-2, and limits of detection LOD 0.048 µg/ml, LOQ 0.161 µg/ml were determined. The method was also applied to pharmaceutical preparations, and the validity of the method was confirmed by standard addition.

Bi-Functional Coated Tapered LPFG Sensor: Gas and Temperature Sensing

A bi-functional coated tapered Long Period Fiber Grating LPFG as a gas and a temperature sensor is proposed. Obtains a sensor with a high sensitivity is still a matter of challenge. In this work, a taper LPFG is used for sensing purposes. Besides, in order to increase the sensor performance, numbers of Cr and Al layers are coated on the taper region. In this work, different concentrations of four gases Ar, NH3, CH4 and N2 are applied for temperature range (25℃ up to 80℃). however, the experimental results illustrate that the transmission loss is reduce which means a significant interaction between sensing medium and cladding mode is occurred successfully which leads to higher sensitivity. Nevertheless, from the main findings, the temperature sensitivities are 2.9 pm/℃, 4.9 pm/℃, 4.5 pm/℃ and 3.1 pm/℃ for 4% concentrations of Ar, NH3, CH4 and N2 respectively. In addition, the gases sensitives are 0.213 nm%-1, 0.41 nm%-1, 0.39 nm%-1, 0.201 nm%-1 with limit of detection LoD of 0.061%, 0.024%, 0.032% and 0.073% for Ar, NH3, CH4 and N2 respectively. Additionally, the sensor shows a good repeatability, recoverability and stability. In terms of stability, the sensor shows a stable value of wavelength shift under different values of gas concentration and temperatures which was estimated 1.55 µm. Besides, it shows a fast responsivity with 53 s and 60 s as response time and recovery time respectively. Interestingly, with less than 0.06 nm of standard deviation, the signal returned to its original resonance wavelength which confirms that this sensor has a good recoverability. From these results, a coated taper LPFG can be a promising candidate for medical and industrial applications.

Development of a simple HPLC procedure for the determination of prochloraz residues in mushrooms

Abstract A simple HPLC-UV procedure is described in our paper which is suitable for the rapid and cost-efficient determination of prochloraz in mushrooms. Prochloraz is the only fungicide in EU which use is allowed in mushroom production. The aim of our work was the development of a simple method that is suitable for the control of this pesticide in everyday analyses during mushroom production. The procedure involves a simple sample preparation method based on solid-liquid extraction (modified QuEChERS extraction method EN 15662) followed by an HPLC-UV determination (recovery: 97–99%; limit of detection LOD: 0.01 mg/kg; limit of quantification LOQ: 0.05 mg/kg).

Purification and Clean-up of 3-NPA from Sugarcane by using Molecularly Imprinted Polymer Solid Phase Extraction Coupled with HPLC-siftdesk

The agricultural product is in constant need of improved analytical techniques that can be used to control the manufacturing process and the food safety of the products. A new selective material based on molecularly imprinted polymers (MIPs) were prepared by bulk polymerization methods and used as solid-phase extraction (SPE) sorbent for sample enhancement of 3-nitropropanic acid (3-NPA) in sugarcane samples prior to high-performance liquid chromatography (HPLC). The objective of this work was to devolved techniques for the extraction, purification, clean up, and preconcentration of 3-NPA from sugarcane samples employing MIP for SPE. The obtained polymers were characterized using field emission scanning electron microscopy, Fourier transforms infrared and the adsorption capacity of SA-SMIP was studied. The developed MISPE method showed excellent linearity in the range of 40–70 mg L with coefficient of determination (r²) >0.9997 and good 3-NPA recoveries of >99% and limits of detection LOD and LOG were ranging from 0.19 mg L to 0.58 mg L, respectively. The method was successfully applied to the analysis of 3-NPA in selected sugarcane samples. MIP-SPE allows not only the analyte to be pre-concentrated but also removed the other compounds from the sample matrix. The MISPE technique has been successfully applied to purification, preconcentration, and clean-up of 3-nitropropionic acid in poisoning sugarcane.

High-performance liquid chromatographic detection of selected phenolic acidsin wine

The aim of this study was to develop a method for identification and quantification of phenolic acids in different wine samples. The simple reversed-phase HPLC-UV method for simultaneous determination of p-coumaric and ferulic acid was developed. The method was validated and working range, linearity, repeatability, accuracy, limit of quantitation LOQ and limit of detection LOD were determined. The linearity of the method was tested in concentration ranges 0.1-1 mg L-1 and 1-10 mg L-1. The correlation coefficients (r2) were greater than 0.996 and quality coefficients (QC) ≤ 5%. Detection limit for both compounds was 0.01 mg L-1. The method is precise (RSD

Synthesis and structure of a new fluorescent sensor based on Ba(II)‐multicarboxylate for detection of Cu2+ ion

AbstractA novel barium(II) coordination polymer (CP), [Ba3(L)2(H2O)4]n 1, has been firstly isolated based on organic ligand 1‐[(2′‐carboxybiphenyl‐4‐yl)methyl]‐2‐propylimidazole‐4,5‐dicarboxylic acid (H3L=(HO2C)2(C3N2)(C3H7)CH2(C6H4)(C6H3)CO2H) by hydrothermal technique, and determined by single‐crystal X‐ray diffractions, elemental analysis, IR, powder X‐ray diffractions (PXRD). The Ba(II)‐CP 1 belongs to a novel 2‐D layer structure created from 1‐D serrated chain containing secondary building unit (SBU) [Ba(1)Ba(2)Ba(3)] via carboxylate group linkage. In 1, the ligand L3− gives a variety of coordinated styles, nonadentate: μ2:(η1η1), μ2:(η1η1), μ3:(η2η2) and decadentate: μ1:(η1η1), μ3:(η2η2), μ3:(η1η2), μ3:(η1η2), which is the first reported example. Moreover, the room‐temperature fluorescent measurements show that the Ba(II)‐CP 1 has specific ability to recognize copper(II) ion in aqueous solution by means of fluorescence quenching effect, corresponding obtained quenching constant Ksv=1.18×102 M−1 and the limit of detection LOD=0.274 μM. Fluorescence titration experiment reveals that there is a good linear relationship between copper ion concentration and fluorescence intensity in the concentration range of 2.0×10−6∼5.3×10−6 mol ⋅ L−1. The corresponding linear equation: y=402.41897–0.70486x, and linear correlation coefficient: R2=0.99866 (λex=310 nm and λem=412 nm).

Hierarchical Porous Carbon Cobalt Nanocomposites-Based Sensor for Fructose

3D hierarchical graphitic carbon nanowalls encapsulating cobalt nanoparticles HPC-Co were prepared in high yield from solid-state pyrolysis of cobalt 2,2′-bipyridine chloride complex. Annealing of HPC-Co in air gave HPC-CoO, which consists of a mixture of crystallite Co3O4 nanospheres and nanorods bursting out of mesoporous carbon. Both nanocomposites were fully characterized using SEM, TEM, BET, and powder X-ray diffraction. The elemental composition of both nanocomposites examined using SEM elemental mapping and TEM elemental mapping supports the successful doping of nitrogen. The powder X-ray diffraction studies supported the formation of hexagonal cobalt in HPC-Co, and cubic crystalline Co3O4 with cubic cobalt in HPC-CoO. HPC-Co and HPC-CoO can be used as a modified carbon electrode in cyclic voltammetry experiments for the detection of fructose with limit of detection LOD 0.5 mM. However, the single-frequency impedimetric method has a wider dynamic range of 8.0–53.0 mM and a sensitivity of 24.87 Ω mM−1 for the electrode modified with HPC-Co and 8.0–87.6 mM and a sensitivity of 1.988 Ω mM−1 for the electrode modified with HPC-CoO. The LOD values are 3 and 4 mM, respectively. The effect of interference increases in the following order: ascorbic acid, ethanol, urea, and glucose. A simple method was used with negligible interference from glucose to measure the percentage of fructose in a corn syrup sample with an HPC-CoO electrode. A specific capacitance of 47.0 F/g with 76.6% retentivity was achieved for HPC-Co and 28.2 F/g with 87.9% for HPC-CoO for 3000 charge–discharge cycles. Thus, (1) has better sensitivity and specific capacitance than (2), because (1) has a higher surface area and less agglomerated cobalt nanoparticles than (2).

New Strategy against COVID-19: L-Serine Doped QDs for Fast Detection of COVID-19 and Blocking of S-Protein

To detect COVID-19, the reverse transcription-polymerase chain reaction (RT-PCR) is usually used but there is a number of faulty tests or an inexact diagnostic, especially in the primordial period of infection. In this regard, the optical response of hybrid quantum dots (QDs): L-serine is presented for the first time as a new and rapid method of detection. QDs were further conjugated with anti-infectious viruses’ antibodies. The detection of a target analyte is increased due to the fact that the final formed hybrid system is exposed to doses of L-serine optically active. QDs acts as L-Serine’s host. This last will trap the virus and emerges less/high photoluminescence (PL) response depending on the L-serine, virus, and doping concentrations. Such rapid optical treatment will inform us of the infection state faster and more efficiently than ELISA tests. The fluorescence properties of the new hybrid system permit a control of coronavirus with a limit of detection LOD ∼80 EID/50 μl thanks to families of clusters induced by L-serine’s molecules. Families of L-serine clusters with inhomogeneous densities can block the S-protein in COVID-19. Moreover, the detection can be issued by trapping the virus with the same dopant.

Highly Sensitive Adsorptive Stripping Voltammetric Method for Sitagliptin Determination on Renewable Amalgam Film Electrode

Highly sensitive voltammetric method for sitagliptin (STG) determination was developed. As working electrode cyclic renewable amalgam film electrode Hg(Ag)FE was used (surface area 10.4 mm2). Application of Hg(Ag)FE allowed to improve sensitivity of the method in comparison with HMDE. Instrumental parameters were optimized and were as follow: waiting and sampling time tw = tp = 10 ms, step potential Es = 5 mV and pulse amplitude ΔE = 50 mV. Preconcentration step was carried out at the potential equal to −600 mV for 15 s. Supporting electrolyte was optimized: 0.025 M ammonium buffer (pH 8.2). Conducted calibration allowed to determine linear range: 20–140 nM and limit of detection LOD: 2.6 nM (1.3 ng ml−1) (20 s preconcentration time). Based on linear sweep voltammetry (LSV) measurements the possible mechanism of sitagliptin reduction has been proposed. The applicability of the method was confirmed by analysis of commercially available pharmaceutical product containing sitagliptin. Obtained results were in a good agreement with producer’s declaration. Calculated recoveries (102%–107%) proved the accuracy of the method. Signal repeatability expressed as RSD was equal to 3.2% (STG concentration 0.1 μM, n = 5).

Fatty Acid Ethyl Esters in Virgin Olive Oils: In-House Validation of a Revised Method.

The content of fatty acid ethyl esters (FAEEs) is one of the quality parameters to define if an olive oil can be classified as extra virgin as these compounds are considered markers for virgin olive oils obtained from poor-quality olives. In addition, FAEEs can also be indirect markers to detect soft deodorization treatment. In this study, an off-line HPLC-GC-FID method for determination of FAEEs is presented, revising the preparative step and the GC injector required by the official method (EU Reg. 61/2011). After optimization, the method was validated in-house by analyzing several parameters (linearity, limit of detection LOD, limit of quantification LOQ, robustness, recovery, precision, and accuracy) to determine its effectiveness. Linearity was measured in the 2.5–50 mg/L range; furthermore, intra-day and inter-day precision values were lower than 15%, while the LOD and LOQ were lower than 1 and 1.5 mg/kg, respectively, for all compounds considered. The main advantages of this revised protocol are: (i) significant reduction in time and solvents needed for each analytical determination; (ii) application of HPLC as an alternative to traditional LC, carried with manually packed glass columns, thus simplifying the separation step.

Conformable surface acoustic wave biosensor for E-coli fabricated on PEN plastic film

Over the last decades, great effort has gone into developing new biosensor technologies for applications in different fields such as disease diagnosis and detection of pollutants in water and food. Global developments in robotic, IoT technologies and in healthcare sensors require new flexible sensor technologies that are low cost and built from sustainable and reusable or recyclable materials. One of the most promising technologies is based on the development of surface acoustic wave (SAW) flexible biosensors, which are highly reproducible, reliable and wirelessly controllable. This work presents for the first time a novel aluminum nitride (AlN)-based conformable SAW immunosensor fabricated on recyclable polyethylene naphthalate. We apply it to the detection of E.Coli using a faster and innovative functionalization method that exploit Protein-A/antibody affinity. A higher sensitivity (Limit of detection-LoD, 6.54*105 CFU/ml) of the Lamb wave traveling on the polymeric device has been obtained in comparison with SAWs traveling on AlN on silicon substrate (LoD, 1.04*106 CFU/ml). Implementation of a finite element method allowed for the estimation of the single E.Coli mass of approximately 9*10−13 g. This work demonstrates the high biosensing potential of flexible polymeric SAW devices for bacteria contamination control in food chain, water and smart packaging.

Conducting polythiophene/α-Fe2O3 nanocomposite for efficient methanol electrochemical sensor

The combination of inorganic semiconductor metal oxides and organic conducting polymers is a favorable strategy in fabricating electrochemical sensors due to their outstanding electrocatalytic performance. Herein, a novel electrochemical sensor for detection of liquid methanol is fabricated using a modified glassy carbon electrode (GCE) with Nafion binder. The active sensing material is composed of a conductive polythiophene (PTh) doped iron oxide (α-Fe2O3) that simply synthesized by a facile sol-gel route in presence of a structure directing agent F127 followed by an oxidative polymerization process. Cyclic voltammetry and electrochemical impedance measurements revealed enhanced electrocatalytic response at the PTh/α-Fe2O3/Nafion modified GCE compared to either α-Fe2O3/GCE or bare GCE with a diffusion-controlled kinetics in ferro/ferricyanide redox couple. Material characterization using various analytical techniques confirmed the formation of PTh sheets onto highly crystalline rhombohedral structure of α-Fe2O3 with distinctly lattice fringes 0.37 nm. Outstanding sensing parameters are achieved with a sensor sensitivity of 0.793 μAmM−1cm−2, limit of detection LOD at (S/N = 3) = 1.59 mM, a wide range of methanol concentration from 5 to 1000 mM with a correlation coefficient R2 = 0.9483. Furthermore, the current proposed sensor electrode showed adequate operational stability and acceptable reproducibility and repeatability.