Correction: Development of electrochemical sensors for quick detection of environmental (soil and water) NPK ions.

[This corrects the article DOI: 10.1039/D4RA00034J.].

Zinc oxide nanorod/rutin modified electrode for the detection of Thiourea in real samples.

In this work, a novel electrochemical detection strategy was developed based on a metal-organic framework of zinc oxide nanorod nanoparticles and rutin for selective screening of Thiourea as toxic chemicals. The zinc oxide nanorod were synthesized by following direct chemical precipitation methods and characterized by X-ray diffraction and X-ray photoelectron spectroscopy analysis. The surface of modified electrodes was also characterized by field emission scanning electron microscopes, energy-dispersive X-ray spectroscopy, and attenuated total reflectance flourier transform infrared spectroscopy. Furthermore, the electrochemical activity of the developed sensor was tested by cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy. The modified electrode showed outstanding electro-catalytic activity towards the detection of Thiourea in phosphate buffer saline at a high pH level of 12.0. The proposed sensor showed a linear range of linearity in a concentration ranging from 5.0 × 10-6 - 900 × 10-6 molL-1 and a detection limit of 2.0 × 10-6 molL-1. Moreover, the selectivity of the developed electrochemical sensor was investigated for the detection of Thiourea in the presence of organic compounds and a group of anions. Furthermore, the proposed strategy demonstrated an excellent recovery value in the spiked farmland water and fruit juice sample.

Poly(3,4-ethylenedioxythiophene):Polystyrene Sulfonate-Modified Electrode for the Detection of Furosemide in Pharmaceutical Products.

Furosemide (4-chloro-2-(furan-2-ylmethylamino)-5-sulfamoyl benzoic acid) is a widely used, FDA-approved drug prescribed for several symptoms associated with heart, kidney, liver failure, or chronic high blood pressure. In this work, a glassy carbon working electrode modified with poly(3,4-ethylenedioxythiophene):polystyrene sulfonate is developed to detect furosemide (FURO) with high sensitivity and precise selectivity. The modified electrode was also characterized using field emission scanning electron microscopy, attenuated total reflectance-Fourier transform infrared, and cyclic voltammetry. Here, an efficient and cost- and time-efficient technique to study the furosemide mechanism of reaction in an acidic liquid medium is presented. An electrochemical oxidation of loop diuretic furosemide was investigated in a supporting electrolyte, 0.01 M of phosphate buffer (at a pH level of 4.0) at 25 ± 0.1 °C using a differential pulse voltammetric (DPV) technique. Under optimized parameters, the developed sensor displays a wide detection range of furosemide concentrations of 6.0 × 10-6 to 1.0 × 10-4 M with a detection limit of 2.0 × 10-6 M using DPV. The presented sensor offers a robust and high-precision technique with an excellent reproducibility to detect furosemide in as a real sample such as urine and pharmaceutical products.

Synthesis, characterization and application of a novel polyazo dye as a universal acid-base indicator.

A novel organic polyazo dye is synthesized by the diazotization of aromatic aniline, followed by coupling it with sulfanilic acid and N,N-dimethylaniline. Characterization was done by 1H-NMR, 13C-NMR, and FTIR spectroscopy. Differential scanning calorimetry (DSC) reveals that phase transition for this molecule is exothermic. The optical band gap is estimated from the absorption cutoff point using UV-Visible spectroscopy. Thermal gravimetric analysis (TGA) addresses the thermal stability of the molecule and is found to be at ∼250 °C. The structure of the synthesized molecule is analogous to that of methyl orange and contains three azo groups. These three azo groups help accept more than two protons and provide two pK a values when diprotic acid or a mixture of acids is used in different titrations. Specifically, when a polybasic acid is in strong base titration, the pK a values were found to be 3.5 and 9.1. Moreover, for strong base and (strong + weak) acid mixture titration, the pK a values are found to be 9.2 and 3.3. Furthermore, the pK a values are found to be 8.6 and 2.8 for (strong and weak) base mixture and (strong and weak) acid mixture titration, respectively. Owing to its increased proton accepting capacity, it can be found in the two pH ranges of 2.1-3.8 for orange color and 8.2-9.8 for yellow color, thus indicating a unique property as a universal indicator for acid-base titration. The dissociation constant of this dye is found to be 3.4 × 10-6, determined in a mixed aqueous solution of 10 wt% ethanol, and a linear relationship between pK a and pH is observed in this solvent system.

Synthesis and Characterization of a Mixed Nanofertilizer Influencing the Nutrient Use Efficiency, Productivity, and Nutritive Value of Tomato Fruits.

Due to the higher potential for enhancing nutrient use efficiency, nanofertilizer (NF) is crucial in sustainable crop production. Thus, foliar-applied mixed nanofertilizer (MNFf) and commercial fertilizer (CF) into the soil (CFs) were claimed together ([MNFf + CFs]) and comparative nutrient use efficiency (NUE), productivity, and nutritional properties of tomato fruits were investigated. The mixed nanofertilizer (MNF) was prepared in our laboratory and characterized using scanning electron microscopy, X-ray diffraction, and Fourier transform infrared. To avoid the interference of other factors, all the treatments were divided into three groups: (i) blank treatment (no fertilizer), (ii) CF treatment, and (iii) combined [MNFf + CFs] treatment. The vegetative growth and qualitative and quantitative attributes of tomatoes were recorded, and the NUE, total production, and benefit-cost ratio (BCR) were also calculated. In addition, comparative nutritional properties for all treatments were analyzed. The plant's height, stem diameter, root length, photosynthetic pigments, leaf minerals, and qualitative traits of tomato fruits were significantly (p < 0.05) increased by [MNFf + CFs] treatment compared to CFs. The protein, fiber, Fe, Zn, and K contents were significantly (p < 0.05) increased by 23.80, 38.10, 44.23, 60.01, and 2.39%, respectively, with the [MNFf + CFs] treatment as compared to CFs, while the ash and protein contents were both lower than the untreated tomato. Moreover, [MNFf + CFs] treatment has significantly (p < 0.05) increased the antioxidant properties. The NUE, total production, and BCR were also increased by 26.08, 26.04, and 25.38%, respectively, with the same treatment. Thus, [MNFf + CFs] treatment could be a potential alternative for reducing the excess use of CF.

Formulation of a Hybrid Nanofertilizer for Slow and Sustainable Release of Micronutrients.

In this work, we have proposed a new formulation of a hybrid nanofertilizer (HNF) for slow and sustainable release of nutrients into soil and water. Urea-modified hydroxyapatite was synthesized, which is a rich source of nitrogen, calcium, and phosphate. Nanoparticles such as copper, iron, and zinc were incorporated into urea-modified hydroxyapatite to increase the efficiency of the proposed fertilizer. Different techniques including powder X-ray powder diffraction, Fourier-transform infrared spectroscopy, and scanning electron microscopy were used to get insight into the properties, morphology, and structure of the as-prepared fertilizer. The developed HNF was used in a field experiment on the ladies' finger (Abelmoschus esculentus) plant. The slow release of HNF was observed during leaching studies and confirmed the availability of Ca2+, PO4 3-, NO2-, NO3-, Cu2+, Fe2+, and Zn2+. Furthermore, the presence of Cu2+, Fe2+, and Zn2+ nutrients in ladies' finger was confirmed by the inductively coupled plasma-optical emission spectrometry (ICP-OES) experiment. A considerable increase in the physicochemical properties such as swelling ratio and water absorption and retention capacities of the proposed fertilizer was observed, which makes the fertilizer more attractive and beneficial compared with the commercial fertilizer. The composition of the proposed HNF was functionally valuable for slow and sustainable release of plant nutrients. The dose of prepared HNF applied was 50 mg/week, whereas the commercial fertilizer was applied at a dose of 5 g/week to A. esculentus. The obtained results showed a significant increase of Cu2+, Fe2+, and Zn2+ nutrient uptake in A. esculentus as a result of slow release from HNF.

Electrochemical Detection of Melamine by Using Reduced Graphene Oxide-Copper Nanoflowers Modified Glassy Carbon Electrode.

In this work, a robust and reliable electrochemical sensor was developed for sensitive detection of non-electroactive melamine (MEL) using a modified glassy carbon electrode with ascorbic acid (AA) as the active recognition element. To increase the current signal of AA, the working electrode was successively modified with l-arginine (l-Arg) and reduced graphene oxide-copper nanoflower composite. The voltammetry measurements denoted that the hydrogen bonding was formed between AA and MEL. Using the optimum conditions, the proposed enhanced sensor can detect MEL concentrations ranging from 10 × 10-9 to 9.0 × 10-8 M with a detection limit of 5.0 × 10-9 M that is proportional to the decrease of AA in the anodic peak current. Finally, the proposed sensor was successfully applied for the determination of MEL in commercial infant milk samples and good recovery values were obtained.

On-chip cell lysis by antibacterial non-leaching reusable quaternary ammonium monolithic column.

Reusable antibacterial non-leaching monolithic columns polymerized in microfluidic channels designed for on-chip cell lysis applications were obtained by the photoinitiated free radical copolymerization of diallyldimethylammonium chloride (DADMAC) and ethylene glycol diacrylate (EGDA) in the presence of a porogenic solvent. The microfluidic channels were fabricated in cross-linked poly(methyl methacrylate) (X-PMMA) substrates by laser micromachining. The monolithic columns have the ability to inhibit the growth of, kill and efficiently lyse Gram-positive Micrococcus luteus (Schroeter) (ATCC 4698) and Kocuria rosea (ATCC 186), and Gram-negative bacteria Pseudomonas putida (ATCC 12633) and Escherichia coli (ATCC 35218) by mechanically shearing the bacterial membrane when forcing the cells to pass through the narrow pores of the monolithic column, and simultaneously disintegrating the cell membrane by physical contact with the antibacterial surface of the column. Cell lysis was confirmed by off-chip PCR without the need for further purification. The influence of the cross-linking monomer on bacterial growth inhibition, leaching, lysis efficiency of the monolithic column and its mechanical stability within the microfluidic channel were investigated and analyzed for three different cross-linking monomers: ethylene glycol dimethacrylate (EGDA), ethylene glycol dimethacrylate (EGDMA) and 1,6-hexanediol dimethacrylate (1,6-HDDMA). Furthermore, the bonding efficiency of two X-PMMA substrates with different cross-linking levels was studied. The monolithic columns were shown to be stable, non-leaching, and reusable for over 30 lysis cycles without significant performance degradation or DNA carryover when they were back-flushed between lysis cycles.