Linear Response In Concentration Range Research Articles

Preparation of dyed polymer microspheres by a physical-chemical dual-binding method and their application in lateral flow immunoassay.

Lateral flow immunoassay (LFIA) has shown great competitiveness in point-of-care testing due to its flexibility and simplicity. Dyed polymer microspheres are one of the most widely used marker particles for signal presentation as they are very convenient for visual interpretation, which is one of the most attractive features of LFIA. The color intensity, as the most critical factor, is directly related to the visual effect. In this work, a physical-chemical dual-binding strategy was proposed for the preparation of functionalized dyed microspheres. Bifunctional seed microspheres were synthesized by introducing 4-vinylbenzyl chloride (VBC) into the soap-free emulsion polymerization process, and the effective immobilization of dyes inside and on the surface of the polymer microspheres was achieved by covalent bonding and swelling methods. The microspheres were characterized by SEM, FT-IR spectroscopy and UV-vis spectroscopy. The results showed that the microspheres containing VBC were spherical with an average particle size of 300 nm. When the microspheres were prepared by adding 10 wt% VBC relative to the total monomer, the immobilization amount of 1-[[4-[(dimethylphenyl)azo]dimethyl phenyl]azo]-2-naphthol (Red-27) was increased to 180 mg g-1, which was 1.8 times that of the microspheres without VBC. The resulting nanomaterials were successfully used to establish a lateral flow immunoassay for the detection of COVID-19 virus N protein. The linear response concentration range was 2.64-87.84 COI, and the detection limit was 14.95 COI.

A turn-on fluorescent nanosensor for H2S detection and imaging in inflammatory cells and mice

Hydrogen sulfide (H2S) is an endogenously generated gaseous signaling molecule and is known to be involved in the occurrence and development of inflammation. To better understand its physiological and pathological process of inflammation, reliable tools for H2S detection in living inflammatory models are desired. Although a number of fluorescent sensors have been reported for H2S detection and imaging, water-soluble and biocompatibility nanosensors are more useful for imaging in vivo. Herein, we developed a novel biological imaging nanosensor, XNP1, for inflammation-targeted imaging of H2S. XNP1 was obtained by self-assembly of amphiphilic XNP1, which was constructed by the condensation reaction of the hydrophobic, H2S response and deep red-emitting fluorophore with hydrophilic biopolymer glycol chitosan (GC). Without H2S, XNP1 showed very low background fluorescence, while a significant enhancement in the fluorescence intensity of XNP1 was observed in the presence of H2S, resulting in a high sensitivity toward H2S in aqueous solution with a practical detection limit as low as 32.3 nM, which could be meet the detection of H2S in vivo. XNP1 also has a good linear response concentration range (0–1 μM) toward H2S with high selectivity over other competing species. These characteristics facilitate direct H2S detection of the complex living inflammatory cells and drug-induced inflammatory mice, demonstrating its practical application in biosystems.

Development of UV-Visible spectrophotometric method for the estimation of vildagliptin in different medium

A simple, accurate, precise, cost effective, rapid and sensitive UV/visible spectrophotometric method was developed for the determination of Vildagliptin in active pharmaceutical dosage form. The developed method was validated as per ICH guidelines.The purity of Vildagliptin was characterized by melting point, Fourier Transform Infra-Red and DSC. The drug was analyzed using UV/visible spectrophotometric method was validated in terms of linearity and range. The solvents used was water, 0.1 N HCl and phosphate buffer pH 7.4 and the wavelength corresponding to maximum absorbance of the drug were found at 210 nm.Melting point of drug was found 151.67°C nearly corresponds to its actual melting range. The linear response for concentration range of 2-12 µg/ml of vildagliptin for water, 0.1 N HCl and phosphate buffer pH 7.4 was recorded each with regression coefficient R = 0.9998, 0.9994 and 0.9991 respectively.The drug was confirmed by interpretation of UV spectra. Hence, proposed method stands out validated and shows a linear relationship and thus may be used for routine analysis of Vildagliptin in pharmaceutical dosage forms.

A dicyanoisophorone-quinolinium-based near-infrared-emission fluorescent probe for ratiometric sensing of bisulfite/sulfite in living cells

Sulfur dioxide (SO2), as a known important sulfur oxide in RSS, has an essential role in achieving the homeostasis of organisms. The development of a highly sensitive and selective fluorescent probe for monitoring SO2 is of great interest in understanding its pathophysiology. Herein, we developed a new near-infrared FRET-based fluorescent probe QD, in which quinolinium fluorophore was selected as the donor and the dicyanoisophorone fluorophore was selected as the acceptor. Probe QD had dual colorimetric and ratiometric fluorescence, larger Stokes shift (277 nm) and longer emission wavelength (677 nm). The fluorescence spectrum showed that QD was highly selective and sensitive with excellent linear response concentration range of 2.5–80 μM. Importantly, probe QD allowed detection of SO2 derivatives and bioimaging of lysosome-targeted in live cells.

Kinetics of Drug Molecule Interactions with a Newly Developed Nano-Gold-Modified Spike Protein Electrochemical Receptor Sensor.

In March 2020, the World Health Organization (WHO) declared COVID-19 a pandemic, and the spike protein has been reported to be an important drug target for anti-COVID-19 treatment. As such, in this study, we successfully developed a novel electrochemical receptor biosensor by immobilizing the SARS-CoV-2 spike protein and using AuNPs-HRP as an electrochemical signal amplification system. Moreover, the time-current method was used to quantify seven antiviral drug compounds, such as arbidol and chloroquine diphosphate. The results show that the spike protein and the drugs are linearly correlated within a certain concentration range and that the detection sensitivity of the sensor is extremely high. In the low concentration range of linear response, the kinetics of receptor–ligand interactions are similar to that of an enzymatic reaction. Among the investigated drug molecules, bromhexine exhibits the smallest Ka value, and thus, is most sensitively detected by the sensor. Hydroxychloroquine exhibits the largest Ka value. Molecular docking simulations of the spike protein with six small-molecule drugs show that residues of this protein, such as Asp, Trp, Asn, and Gln, form hydrogen bonds with the -OH or -NH2 groups on the branched chains of small-molecule drugs. The electrochemical receptor biosensor can directly quantify the interaction between the spike protein and drugs such as abidor and hydroxychloroquine and perform kinetic studies with a limit of detection 3.3 × 10−20 mol/L, which provides a new research method and idea for receptor–ligand interactions and pharmacodynamic evaluation.

Electrochemical sensor based on ion-selective membrane of silica/polyaniline nano-composites for selective determination of uranyl ions

Life threatening impacts of uranium have necessitated its detection and determination in economically feasible way before it arrives in living bodies. Therefore, a new form of UO22+ ion-selective electrode has been fabricated based on membrane of silica/polyaniline core-shell nano-composites, in-spite of traditionally used ionophores, because of intrinsically conducting nature of polyaniline. For the synthesis of these nano-composites, silica has been extracted from rice straw in its cristobalite form, whereas the layer of polyaniline shell has been grafted on silica nanoparticles through in-situ chemical oxidative polymerization technique by cautiously maintaining the electro-active nature of these core-shell nano-composites. The chemical composition, purity, topography, morphology and surface polarity of this nano-composite assembly have been studied through various spectroscopic techniques such as, FT-IR, EDS, FESEM, UV–Vis, DLS and Raman spectroscopy. The results confirm that silica/polyaniline nano-composites have been synthesized with desired semi-cavities and electrostatic surface charge, which is responsible for binding with target cation, i.e., UO22+for its potentiometric determination in aqueous medium even in the presence of interfering metal ions. The designed potentiometric sensor has shown fast and stable linear response in concentration range of 1 × 10−6 to 1 × 10−2 M with the limit of detection of 1.4 × 10−7 M which is 100-folds lower than the detection limit calculated using spectrofluorometry. In addition to this, the proposed UO22+ion-selective electrode has been successfully employed as an indicator electrode for the determination of uranyl ions in complexometric titration and for the estimation of UO22+ions in real life based environmental sample, i.e., soil.

Improving the fluorescence intensity of lanthanide-doped microspheres via incorporation of lauryl methacrylate: Synthesis and their application in C-reactive protein detection

Lanthanide-doped microspheres, especially europium complexes, are widely utilized as fluorescent reporters in lateral flow immunoassays. High fluorescence signal output, which is closely associated with the synthesis of microsphere, is critical for this procedure. Here, the interior structure of microspheres was attempted to be adjusted by introducing plasticizer lauryl methacrylate (LMA) into the polymerization of styrene monomer to improve the amount of europium complexes encapsulated in microspheres. The scanning electron microscope (SEM) results showed that the microspheres containing LMA were spherical and uniform in size (the average size 291 nm). A maximal fluorescence signal was reached when the microspheres were prepared by adding 10 wt% LMA relatively to styrene, which is almost three times that of microspheres without LMA. Such elevation in fluorescence signal can be attributed to the increment in content of encapsulated europium complexes (about 47.10 mg/g, which is far higher than other reported methods (3.72 or 1.023 mg/g)) induced by reducing the regularity of the polymer chain and increasing its flexibility as well as distensibility inside microspheres with LMA. Thanks to such superior fluorescence property, lateral flow immunoassay was successfully founded to detect C-reactive protein (CRP) with a linear response in concentration range of 1.3–210.7 μg/L. Therefore, the fundamental advance in this work is to provide the way to adjust the environment inside microspheres for encapsulation of europium complexes, which lays a good foundation for preparing microsphere with high fluorescence intensity.

A novel IL-f-ZnONPs@MWCNTs nanocomposite fabricated glassy carbon electrode for the determination of sulfamethoxazole

• Novel nanocomposite of IL- f -ZnONPs@MWCNTs for the detection of sulfamethoxazole. • IL- f -ZnONPs@MWCNTs promote the electron transfer and provide enhanced performance. • Ultra-sensitivity and selectivity for sulfamethoxazole determination. Sulfamethoxazole (SMZ) is an anti-microbial drug, generally used for adults and children. This work focuses on the development of a novel electrochemical sensor for the determination of SMZ in pharmaceutical samples. It deals with a nanocomposite based on 1-ethyl-3-methylimidazolium dicyanamide ionic liquid functionalised zinc oxide nanoparticles (IL- f -ZnONPs) and multiwalled carbon nanotubes (MWCNTs) fabricated glassy carbon electrode (GCE). The synthesised nanocomposite was characterised by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM). Furthermore, the electrochemical behaviour of the IL- f -ZnONPs@MWCNTs@GCE was examined by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Under the optimum conditions, the IL- f -ZnONPs@MWCNTs@GCE exhibited greater wide linear response in concentration range of 0.1–10 ng mL −1 with a limit of detection (LOD) and limit of quantification (LOQ) of 0.1 ng mL −1 and 0.2140 ng mL −1 respectively. The developed IL- f -ZnONPs@MWCNTs@GCE electrochemical sensor have additional advantages for its good stability, selectivity, cost effectiveness, portability and reproducibility. These findings demonstrate that the IL- f -ZnONPs@MWCNTs has large surface area, which promotes electron transfer from SMZ to produce a substrate complex, resulting in a better signal amplification. The electrochemical sensor was active for the detection of SMZ in pharmaceutical samples with recoveries ranging from 99.1% to 102.6%.

Polypyrrole Microsphere Modified Porous UiO-66 for Electrochemical Nitrite Sensing

Herein, A new nanocomposite material (PPy/UiO-66) composed of conductive polypyrrole microspheres(PPy) and UiO-66 was prepared by a simple in situ polymerization method and established a new method for detecting The relationship between the morphology and size of the PPy/UiO-66 interface material and its response performance and electrocatalytic performance was studied. The results show that the polypyrrole microspheres are uniformly compounded on the outer surface of the metal organic framework (MOF), which improves the surface properties of the material and greatly improves the conductivity of the MOF material. The particle size of the composite material is about 200 nm, and the particle size of the polypyrrole microspheres is about 30 nm. Electrochemical performance studies have shown that the composite material has an extended linear response concentration range of 0.05–1055.5 μM for detecting a detection limit of 0.037 μM (S/N = 3), and a sensitivity of 297.7μA mM−1 cm−2. The sensitivity of the sensor to detect nitrite is 2.5 times that of the polymer composite material PANI/SnO2/GCE; and it is an order of magnitude lower than the detection limit of the nitrite sensor based on MOF material. Therefore, the sensor can be used as a potential sensing material for the detection of nitrite.

Catechin-inspired gold nanocluster nanoprobe for selective and ratiometric dopamine detection via forming azamonardine

The sensitive and selective perception of dopamine (DA, a typical neurotransmitter) is important to evaluate the biological environment. In this study, a catechin-functionalized gold nanocluster (C-Au NC) nanoprobe has been explored for the ratiometric DA sensing. The detection mechanism is based on the formation of azamonardine via selective DA-catechin chemical reaction and subsequent enhanced fluorescence emission. Using Au NC emission as the internal reference, ratiometric fluorescence variation is realized, which allows sensitive DA analysis with a limit of detection of 1.0 nM (S/N = 3) and linear response concentration range from 0 to 500 nM. The characteristic chemical reaction between catechin and DA affords favorable selectivity over other amino acids, metal ions and small molecules. In addition, the practical application of the proposed nanoprobe is validated by the accurate detection of DA content in urea and cell lysate samples.

RP-HPLC Method Development and Validation for Simultaneous Estimation of Thymoquinone and Curcumin in Dosage form

Aim: The aim of work is to develop and validate simple, specific, accurate, precise HPLC method for the estimation of Curcumin (CUR) and Thymoquinone (THQ) simultaneously in bulk and its formulation as per ICH guidelines for analytical method development and validation.
 Study Design: Developing RP-HPLC method using C-18 Inertsil column and optimization of variables for estimation of Thymoquinone and Curcumin in bulk and formulation.
 Place and Duration of Study: The present work was carried out at Shri D. D. Vispute College of Pharmacy and Research Center, Panvel in year 2021.
 Methodology: The RP-HPLC method was developed with an isocratic condition of mobile phase comprising acetonitrile and water in a ratio of (82:18) v/v, at a flow rate of 0.9 mL/minute over Inertsil ODS, 250× 4.6 mm, 5 µm column, at 30°C column oven temperature. Photodiode array at 256 nm was used for detection
 Results: Retention time for curcumin and thymoquinone was found to be 3.5 and 4.3 mins respectively. The method showed excellent linear response in concentration range of 4-18 µg/mland 10-45 µg/mlfor thymoquinone and curcuminrespectively with correlation coefficient (R2) values of0.999 for both. System precision and method precision studies were less than the maximum allowable limit percentage of relative standard deviation ≤ 2.0 i.e., 1.61 % and 1.62 % for curcumin and 0.47 % and 0.42 % for thymoquinone respectively. Mean % Recovery for both the drugs were within acceptance limits. The developed and validated HPLC method is simple, accurate, precise and suitable for analysis as all the results were within acceptance criteria.
 Conclusion: The developed RP-HPLC method at single wavelength was validated according to ICH guideline with respect to system suitability, specificity, linearity, accuracy, precision and robustness and can be used for routine quality monitoring of drug in pharmaceutical dosage form.

Rapid recognition of di-n-butyl phthalate in food samples with a near infrared fluorescence imprinted sensor based on zeolite imidazolate framework-67

Di-n-butyl phthalate (DBP) as a plasticizer is widely used in food and chemical industries. It is harm to human health when it appeared in food and water. A novel near-infrared (NIR) fluorescence molecularly imprinted sensor based on CdTe quantum dots and zeolite imidazolate framework-67 was developed with a sol–gel polymerization method for rapid and sensitive determination of DBP in foodstuff rapidly (only in 1.5 min). The fluorescence imprinted sensor provided a rapid detection method for DBP in the linear response concentration range of 0.05–18.0 μM with a low detection limit of 1.6 nM. Compared with previous fluorescence imprinted sensor, it behaved faster response speed and lower detection limit for determination of DBP. The fluorescence imprinted sensor was used to detect DBP in real samples successfully with satisfied recoveries of 97.2–106.4%, suggesting a potential application in food analysis.

Concentration-modulated dual-excitation fluorescence of carbon dots used for ratiometric sensing of Fe3+

The development of ratiometric fluorescence sensing platforms with simple synthetic routes and good anti-interference capacities are of great importance for their further application. Herein, hyperbranched polyethylenimine passivated carbon dots (HPEI-CDs) with concentration-modulated dual-excitation fluorescence property were synthesized. At a low concentration, HPEI-CDs only showed one fluorescence center, while at a relatively high concentration, its excitation peak around 355 nm would split into two peaks. Energy level splitting and broadening were demonstrated to be the origin of such dual-excitation behavior. Based on the dual-excitation signals, HPEI-CDs could serve as a ratiometric sensor for the detection of Fe3+ in aqueous solution. The assay exhibited a wide linear response concentration range (2–360 μM) with a limit of detection of 0.47 μM. Significantly, benefiting from the high concentration of HPEI-CDs, the sensor showed good selectivity and excellent anti-interference capacity. In addition, this nanosensor was successfully applied for the detection of Fe3+ in real water samples with satisfactory recoveries.

Microwave-assisted synthesis of fluorescent silicon quantum dots for ratiometric sensing of Hg (II) based on the regulation of energy transfer

The rapid and sensitive detection of Hg2+ is highly required to protect the environmental safety and human healthy. In the present work, a ratiometric fluorescent sensing platform, consisting of silicon quantum dots (SiQDs), Rox-labelled DNA (Rox-DNA), and Exonuclease III (Exo III), is developed for the accurate detection of Hg2+. As for fluorescent probe, we report the first use of glutathione as reduction reagent for the microwave synthesis of SiQDs, achieving the facile (using a house-hold microwave oven) and rapid (within 8 min) synthesis. Such SiQDs show pH-independent spectra and reversible fluorescent behavior with temperature. Moreover, experimental results revealed that the electrostatic interaction-induced aggregation of Rox-DNA and SiQDs facilitated the occurring of energy transfer (ET). And detection principle based on the regulation of ET between Rox and SiQDs with Exo III was designed for analysis. ET effect resulted in the fluorescent fading of Rox while that of SiQDs kept stable. For analysis, the addition of Hg2+ led to the formation of double-stranded Rox-DNA via T-Hg2+-T. Exo III would cut these double-stranded DNA to release Rox and Hg2+, thereby impeding the ET effect and recovering the fluorescent of Rox. Such SiQDs/Rox-DNA/Exo III ratiometric fluorescent sensing platform exhibited a linear response concentration range of 0.02 nM–10 nM with a detection limit of 0.01 nM. It was successfully used to analyze the water and soil samples. The reliability was validated by ICP-MS. Our work should promote the practical application of ratiometric fluorescent assay.

Naphthalimide-based a highly selective two-photon fluorescent probe for imaging of hydrogen sulfide in living cells and inflamed tissue of mouse model.

Hydrogen sulfide (H2S) is a very important third endogenously generated gaseous signaling molecule and plays a key role in physiological and pathological regulation processes of living biosystems. Although a lot of H2S fluorescent probes have been reported, the relationship between the physiology and pathology of H2S in inflamed tissues remains unclear. Herein, by adopting a donor-π-acceptor (D-π-A)-structured naphthalimide derivative as the two-photon (TP) fluorophore and a 4-dinitrobenzene-ether (DNB) with a strong intramolecular charge transfer (ICT) effect as the recognition moiety, we reported a novel TP bioimaging probe NP-H2S for H2S with improved sensitivity. The NP-H2S exhibits very low background fluorescence in the absence of H2S, and a significant 258-fold fluorescence intensity enhancement was observed in the presence of H2S, resulting in a high sensitivity and selectivity to H2S in aqueous solutions with a detection limit of 18.8nM observed. The probe also shows a wide linear response concentration range (0-10.0μM) to H2S with high selectivity. All these features are favorable for direct monitoring of H2S in complex biological samples. It was then applied for direct TP imaging of H2S in tissues of inflammation model with satisfactory sensitivity, indicating it has the latent capability in further biological applications for investigation of the interaction H2S with inflammation.

A new electrochemical sensor for simultaneous detection of sulfamethoxazole and trimethoprim antibiotics based on graphene and ZnO nanorods modified glassy carbon electrode

A novel electrochemical sensor based on graphene (GR) and ZnO nanorods (GR-ZnO/GCE) was developed to detect sulfamethoxazole (SMX) and trimethoprim (TMP) simultaneously. SEM image showed that ZnO had a rod shaped morphology. XRD result indicated a hexagonal wurtzite phase of ZnO nanorods. The electrochemical experiment results showed that the synergetic effect of GR and ZnO endowed the prepared sensor excellent electrocatalytic behavior towards the oxidation of SMX and TMP. SMX and TMP were detected by DPV method at 0.85 V and 1.06 V, respectively. Under the optimal conditions, the GR-ZnO/GCE showed superior wide linear responses in concentration range of 1–220 μmol/L for SMX and 1–180 μmol/L for TMP with the limit of detection (LOD) of 0.4 μmol/L and 0.3 μmol/L, respectively. In addition, the sensor has good stability, good selectivity, anti-jamming ability and reproducibility. We tested SMX and TMP in lake water, tap water, urine and serum with recovery between 93.2% and 108%. The proposed sensor has a good application prospect in biomedicine and environmental protection.

Analytical Method Development and Validation of UV-visible Spectrophotometric Method for the Estimation of Vildagliptin in Gastric Medium

Vildagliptin is an antidiabetic agent, belongs to the dipeptidyl peptidase IV (DPP-4) inhibitors. The aim of investigation was to develop a simple UV-visible Spectrophotometric method for the determination of vildagliptin in its pure form and pharmaceutical formulations, further to validate the developed method. Vildagliptin was estimated using UV-Visible double beam spectrophotometer at the wavelength of maximum absorption (210 nm) in acidic medium containing 0.1N HCl. The drug was characterized by melting point, Differential Scanning Calorimetry (DSC), and Fourier Transform Infra-Red (FTIR) techniques. The analysis of the drug was carried out by novel UV-Visible method which was validated analytical parameters like linearity, precision, and accuracy as per guidelines laid down by International Conference on Harmonization (ICH). Melting point of drug was found 154°C which is corresponds to its actual melting range. Similarly by the interpretation of spectra the drug was confirmed. The linear response for concentration range of 5-60 µg/ml of vildagliptin was recorded with regression coefficient 0.999. The accuracy was found between 98-101%. Precision for intraday and interday was found to be 1.263 and 1.162 respectively, which are within the limits. To establish the sensitivity of the method, limit of detection (LOD) and limit of quantification (LOQ) were determined which were found to be 0.951 µg/ml and 2.513 µg/ml respectively. The UV method developed and validated for vildagliptin drug was found to be linear, accurate, precise and economical which can be used for the testing of its pharmaceutical formulations.

Simultaneous determination of 4-aminophenol and acetaminophen based on high electrochemical performance of ZIF-67/MWCNT-COOH/Nafion composite

Herein, a novel electrochemical sensor based on ZIF-67/MWCNT-COOH/Nafion composite was designed and prepared for simultaneous detection of 4-aminophenol (4-AP) and acetaminophen (AMP). The electrochemical behaviors of the 4-AP and AMP on the ZIF-67/MWCNT-COOH/Nafion electrode were explored via cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The results exhibited that the designed electrochemical sensor possessed superior electrocatalytic activity for 4-AP and AMP, which was attributed to the highly ordered porous structure of ZIF-67, the outstanding electrical conductivity and high electrocatalytic activity of MWCNT-COOH. Under optimization conditions, the DPV response of the prepared electrode depicted a wider linear response concentration range of 0.2 to 200 μM for 4-AP, and 0.1 to 100 μM for AMP, respectively. And the lower detection limits (LOD) of 0.01 and 0.07 μM were obtained for 4-AP and AMP, respectively. More importantly, the acquired electrode was applied to Yellow river water and Paracetamol tablets for analysis of 4-AP and AMP, which exhibited satisfying recovery of 98.2% ~ 106.7% for 4-AP and 94.7% ~ 99.6% for AMP, respectively. In a word, the constructed electrochemical sensing platform delivered a promising potential in real application.

Bi2O3/ZnO nanocomposite: Synthesis, characterizations and its application in electrochemical detection of balofloxacin as an anti-biotic drug

In the present work, a chemically modified electrode has been fabricated utilizing Bi2O3/ZnO nanocomposite. The nanocomposite was synthesized by simple sonochemical method and characterized for its structural and morphological properties by using XRD, FESEM, EDAX, HRTEM and XPS techniques. The results clearly indicated co-existence of Bi2O3 and ZnO in the nanocomposite with chemical interaction between them. Bi2O3/ZnO nanocomposite based glassy carbon electrode (GCE) was utilized for sensitive voltammetric detection of an anti-biotic drug (balofloxacin). The modification amplified the electroactive surface area of the sensor, thus providing more sites for oxidation of analyte. Cyclic and square wave voltammograms revealed that Bi2O3/ZnO modified electrode provides excellent electrocatalytic action towards balofloxacin oxidation. The current exhibited a wide linear response in concentration range of 150–1000 nM and detection limit of 40.5 nM was attained. The modified electrode offered advantages in terms of simplicity of preparation, fair stability (RSD 1.45%), appreciable reproducibility (RSD 2.03%) and selectivity. The proposed sensor was applied for determining balofloxacin in commercial pharmaceutical formulations and blood serum samples with the mean recoveries of 99.09% and 99.5%, respectively.

Development of reproducible thiourea sensor with binary SnO2/V2O5 nanomaterials by electrochemical method

In this methodology, the thiourea (TU)sensor was made-up by means of glassy carbon electrode (GCE) layered by the wet-chemically prepared binary SnO2/V2O5 nanomaterials (NMs). The existence of SnO2 and V2O5 in prepared spherical NPs were categorized by X-ray photoelectron spectroscopy (XPS), Field Emission Scanning Electron Microscopy (FESEM), Energy-dispersive X-ray spectroscopy and X-ray Powder Diffraction (XRD). The TU sensor was displayed the linear responses in concentration range (LDR) of 0.1 nM ~ 0.01 mM. The calibration curve of TU sensor was made by plotting current verses concentration of TU, which was measured by electrochemical technique. The sensitivity and lower limit of detection (DL) for TU sensor were calculated from calibration curve, which are found as 17.0918 µAµM-1cm−2 and 95.40 ± 4.77 pM respectively. The analytical parameters of TU sensor such as reproducibility, response time and stability were measured and found efficient results. It also was validated in the detection of TU in presence of real bio-samples. Thus, this unique and prospective method is introduced to develop the selective biosensor by electrochemical approach, which might be a pioneer sensor probe for its simple and reliable approach for the safety of healthcare and biomedical fields in a large scales.