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

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

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

All over the world, technology is becoming more and more prevalent in agriculture. Different types of instruments are already being used in this sector. For the time being, every farmer is trying to produce more crops on a piece of land. Eventually, soil loses its nutrients; however, to grow more crops, farmers use more fertilizers without knowing the proper conditions of the soil in real time. To overcome this issue, many scientists have recently focused on developing electrochemical sensors to detect macronutrients, i.e., nitrogen (N), phosphorus (P), and potassium (K), in soil or water rapidly. In this review, we focus mainly on the recent developments in electrochemical sensors used for the detection of nutrients (NPK) in different types of samples. As it is outlined, the use of smart and portable electrochemical sensors can be helpful for the reduction of excess fertilizer and can play a vital role in maintaining suitable conditions in soils and water. We are optimistic that this review can guide researchers in the development of a portable and suitable NPK detection system for soil nutrients.

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.

Nanostructured wearable electrochemical and biosensor towards healthcare management: a review.

In recent years, there has been a rapid increase in demand for wearable sensors, particularly these tracking the surroundings, fitness, and health of people. Thus, selective detection in human body fluid is a demand for a smart lifestyle by quick monitoring of electrolytes, drugs, toxins, metabolites and biomolecules, proteins, and the immune system. In this review, these parameters along with the main features of the latest and mostly cited research work on nanostructured wearable electrochemical and biosensors are surveyed. This study aims to help researchers and engineers choose the most suitable selective and sensitive sensor. Wearable sensors have broad and effective sensing platforms, such as contact lenses, Google Glass, skin-patch, mouth gourds, smartwatches, underwear, wristbands, and others. For increasing sensor reliability, additional advancements in electrochemical and biosensor precision, stability in uncontrolled environments, and reproducible sample conveyance are necessary. In addition, the optimistic future of wearable electrochemical sensors in fields, such as remote and customized healthcare and well-being is discussed. Overall, wearable electrochemical and biosensing technologies hold great promise for improving personal healthcare and monitoring performance with the potential to have a significant impact on daily lives. These technologies enable real-time body sensing and the communication of comprehensive physiological information.

Copper oxide nanoflowers/poly-l-glutamic acid modified advanced electrochemical sensor for selective detection of l-tryptophan in real samples.

The main objective of this research work is to develop a low-cost sensor to detect l-tryptophan (L-tryp) in real sample medium based on a modified glassy carbon electrode. For this, copper oxide nanoflowers (CuONFs) and poly-l-glutamic acid (PGA) were used to modify GCE. The prepared NFs and PGA coated electrode was characterized using field emission scanning electron microscope (FE-SEM) with energy dispersive X-ray (EDX) and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. Furthermore, the electrochemical activity was performed by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). The modified electrode showed excellent electro-catalytic activity towards L-tryp detection in PBS solution at neutral pH 7.0. Based on the physiological pH condition, the proposed electrochemical sensor can detect L-tryp concentration with a linear range of 1.0 × 10-4-8.0 × 10-8 molL-1 with having a detection limit of 5.0 × 10-8 molL-1 and sensitivity of 0.6µA/µMcm2. The selectivity of L-tryp was tested with a mixture of salt and uric acid solution at the above conditions. Finally, this strategy demonstrated excellent recovery value in real sample analysis like milk and urine.

Label free flexible electrochemical DNA biosensor for selective detection of Shigella flexneri in real food samples.

An effective tool for early-stage selective detection of the foodborne bacterial pathogen Shigella flexneri (S. flexneri) is essential for diagnosing infectious diseases and controlling outbreaks. Here, a label-free electrochemical DNA biosensor for monitoring S. flexneri is developed. To fabricate the biosensor, detection probe (capture probe) is immobilized on the surface of poly melamine (P-Mel) and poly glutamic acid (PGA), and disuccinimidyl suberate (DSS) functionalized flexible indium tin oxide (ITO) electrode. Anthraquinone-2-sulfonic acid monohydrate sodium salt (AQMS) is used as a signal indicator for the detection of S. flexneri. The proposed DNA biosensor exhibits a wide dynamic range with concentration of the targets ranging from 1 × 10-6 to 1 × 10-21 molL-1 with a limit of detection (LOD) of 7.4 × 10-22 molL-1 in the complementary linear target of S. flexneri, and a detection range of 8 × 1010-80 cells/ml with a LOD of 10 cells/ml in real S. flexneri sample. The proposed flexible biosensor provides high specificity for the detection of S. flexneri compared to other target signals such as discrete base mismatches and different bacterial species. The developed biosensor displayed excellent recoveries in detecting S. flexneri in spiked food samples. Therefore, the proposed biosensor can serve as a model methodology for the detection of other pathogens in a broad span of industries.

Development of a hematite nanotube and tyramine-based drug carrier against drug-resistant bacteria Klebsiella pneumoniae.

In this study, hematite nanotube (HNT) and tyramine-based advanced nano-drug carriers were developed for inhibiting the growth of Klebsiella pneumoniae (K. pneumoniae). The HNT was synthesized by following the Teflon line autoclaved assisted hydrothermal process and tyramine was incorporated on the surface of the HNT to fabricate the formulated nano-drug. The nano-drug was prepared by conjugating meropenem (MP) on the surface of Tyramine-HNT and characterized using different techniques, such as scanning electron microscopy (SEM), attenuated total reflection Fourier transform infrared (ATR-FTIR), etc. Furthermore, the drug-loading efficiency and loading capacity were measured using a UV-vis spectrometer. The pH, amount of Tyr, and HNT required for drug loading were optimized. A controlled and gradual manner of pH-sensitive release profiles was found after investigating the release profile of MP from the carrier drug. The antibacterial activity of MP@Tyramine-HNT and MP was compared through the agar disc diffusion method which indicates that antibacterial properties of antibiotics are enhanced after conjugating. Surprisingly, the MP@Tyramine-HNT exhibits a minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of K. pneumoniae lower than MP itself. These results indicate the nanocarrier can reduce the amount of MP dosed to eradicate K. pneumoniae.

Graphitic carbon nitride and APTES modified advanced electrochemical biosensor for detection of 17ß-estradiol in spiked food samples.

This work demonstrates a simple and inexpensive electrochemical biosensing pathway for selective and sensitive recognition of 17ß-estradiol (E2) in environmental and food samples. The biosensing system is based on graphitic carbon nitride (g-C3N4) and a conductive polymer 3-aminopropyltriethoxysilane (APTES). The proposed biosensor shows the ability to detect E2 in attomolar levels within a wide linear logarithm concentration range of 1 × 10-6 to 1 × 10-18 mol L-1 with a limit of detection (LOD) of 9.9 × 10-19 mol L-1. The selectivity of the developed biosensor was confirmed by conducting the DPV of similarly structured hormones and naturally occurring substances. The proposed biosensor is highly stable and applicable to detect E2 in the presence of spiked food and environmental samples with satisfactory recoveries ranging from 95.1 to 104.8%. So, the designed electrochemical biosensor might be an effective alternative tool for the detection of E2 and other endogenous substances to attain food safety.

A DNA functionalized advanced electrochemical biosensor for identification of the foodborne pathogen Salmonella enterica serovar Typhi in real samples.

An efficient platform for the detection of Salmonella enterica serovar Typhi (S. Typhi) is essential for early-stage diagnosis of typhoid to prevent and contain outbreaks. Here, we fabricated an electrochemical DNA biosensor for selective identification of S. Typhi in real samples. The biosensor has been fabricated by immobilizing an amine labelled S. Typhi specific single-strand capture probe on the surface of gold nanoparticles (AuNP) and poly cysteine (P-Cys) modified screen-printed electrode. Differential pulse voltammetry (DPV) of anthraquinone-2-sulfonic acid monohydrate sodium salt (AQMS) as a signal indicator was monitored to detect S. Typhi by hybridization of target DNA with the probe DNA. The fabricated biosensor shows a detection range of 1 × 10-6 to 1 × 10-22 molL-1 with a LOD of 6.8 × 10-25 molL-1 in S. Typhi complementary linear target and 1.8 × 105 to 1.8 CFUml-1 with a LOD of 1 CFUml-1 in a real S. Typhi sample. The biosensor shows excellent discrimination ability to some bases mismatched and different bacterial cultures (same and distant genera). The most beneficial points of the proposed DNA biosensor are the lower limit of detection and the ability to reuse the biosensor more than 6 to 7 times. In addition, the practicability of the biosensor was investigated via detecting S. Typhi in blood, poultry feces, egg, and milk whereby excellent recoveries ranging from 96.54 to 103.47% were demonstrated indicating that this biosensor might be the most promising diagnostic tool for monitoring S. Typhi in clinical and food samples.

Ceftizoxime loaded ZnO/L-cysteine based an advanced nanocarrier drug for growth inhibition of Salmonella typhimurium.

L-Cysteine coated zinc oxide (ZnO) nano hollow spheres were prepared as a potent drug delivery agent to eradicate Salmonella enterica serovar Typhimurium (S. typhimurium). The ZnO nano hollow spheres were synthesized by following the environmentally-friendly trisodium citrate assisted method and L-cysteine (L-Cys) conjugate with its surface. ZnO/L-Cys@CFX nanocarrier drug has been fabricated by incorporating ceftizoxime with L-Cys coated ZnO nano hollow spheres and characterized using different techniques such as scanning electron microscope (SEM), attenuated total reflection Fourier transform infrared (ATR-FTIR), and X-ray diffraction (XRD) etc. Furthermore, the drug-loading and encapsulation efficiency at different pH levels was measured using UV-vis spectrometer and optimized. A control and gradual manner of pH-sensitive release profile was found after investigating the release profile of CFX from the carrier drug. The antibacterial activity of ZnO/L-Cys@CFX and CFX were evaluated through the agar disc diffusion method and the broth dilution method, which indicate the antibacterial properties of antibiotics enhance after conjugating. Surprisingly, the ZnO/L-Cys@CFX exhibits a minimum inhibitory concentration (MIC) of 5 µg/ml against S. typhimurium is lower than CFX (20 µg/ml) itself. These results indicate the nanocarrier can reduce the amount of CFX dosed to eradicate S. typhimurium.

Development of an advanced DNA biosensor for pathogenic Vibrio cholerae detection in real sample.

Due to the epidemics of emerging microbial diseases worldwide, the accurate and rapid quantification of pathogenic bacteria is extremely critical. In this work, a highly sensitive DNA-based electrochemical biosensor has been developed to detect Vibrio cholerae using gold nanocube and 3-aminopropyltriethoxysilane (APTES) modified glassy carbon electrode (GCE) with DNA carrier matrix. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) experiments were performed to interrogate the proposed sensor at each stage of preparation. The biosensor has demonstrated high sensitivity with a wide linear response range to target DNA from 10-8 to 10-14 (R2= 0.992) and 10-14 to 10-27 molL-1 (R2= 0.993) with a limit of detection (LOD) value of 7.41 × 10-30 molL-1 (S/N = 5). The biosensor also exhibits a selective detection behavior in bacterial cultures that belong to the same and distant genera. Moreover, the proposed sensor can be used for six consecutive DNA assays with a repeatability relative standard deviations (RSD) value of 5% (n = 5). Besides, the DNA biosensor shows excellent recovery for detecting V. cholerae in poultry feces, indicating that the designed biosensor could become a powerful tool for pathogenic microorganisms screening in clinical diagnostics, food safety, and environmental monitoring.

N-Hydroxysuccinimide crosslinked graphene oxide-gold nanoflower modified SPE electrode for sensitive detection of chloramphenicol antibiotic.

Here we introduce a composite material that consists of graphene oxide (GO) sheets crosslinked with N-hydroxysuccinimide (NHS) and functionalized with gold nanoflowers (AuNFs). Furthermore, a screen printed electrode (SPE) modified with the introduced composite is electrochemically reduced to obtain an SPE/rGO-NHS-AuNFs electrode for sensitive and selective determination of chloramphenicol (CAP) antibiotic drug. The morphological structure of the as-prepared nanocomposite was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, cyclic voltammetry, Fourier-transform infrared spectroscopy and electrochemical impedance spectroscopy. The proposed sensor demonstrated excellent performance with a linear concentration range of 0.05 to 100 µM and a detection limit of 1 nM. The proposed electrode offers a high level of selectivity, stability, reproducibility and a satisfactory recovery rate for electrochemical detection of CAP in real samples such as blood serum, poultry feed, milk, eggs, honey and powdered milk samples. This further demonstrates the practical feasibility of the proposed sensor in food analysis.

A highly sensitive poly-arginine based MIP as an electrochemical sensor for selective detection of dimetridazole.

In this experiment, a highly effective electrochemical sensor based on a molecularly imprinted polymer has been developed for ultrasensitive detection of dimetridazole. The sensor was made by incorporating of dimetridazole as a template molecule during the electropolymerization of poly-arginine on a glassy carbon electrode. The modified electrode GCE/P-Arg@MIP was characterized by voltammetric and microscopic techniques. Differential pulse voltammetry method was used to detect target analyte under the optimum condition. The DPV response to dimetridazole was linear at 0.1 × 10-9 to 10 × 10-6 mol L-1 (R2 = 0.996), with a method detection limit (S/N = 3) of 0.1 × 10-9 mol L-1. Moreover, the proposed sensor shows satisfactory recovery ranges for the determination dimetridazole in commercially available egg, milk and honey samples.