Pesticides released intentionally into the environment and through various processes contaminate the environment. Although pesticides are associated with many health hazards, there is a lack of ...monitoring of these contaminants. Traditional chromatographic methods—high-performance liquid chromatography, capillary electrophoresis, and mass spectrometry—are effective for the analysis of pesticides in the environment but have certain limitations such as complexity, time-consuming sample preparation, and the requirement of expensive apparatus and trained persons to operate. Over the past decades, acetylcholinesterase (AChE) inhibition-based biosensors have emerged as simple, rapid, and ultra-sensitive tools for pesticide analysis in environmental monitoring, food safety, and quality control. These biosensors have the potential to complement or replace the classical analytical methods by simplifying or eliminating sample preparation and making field-testing easier and faster with significant decrease in cost per analysis. This article reviews the recent developments in AChE inhibition-based biosensors, which include various immobilization methods, different strategies for biosensor construction, the advantages and roles of various matrices used, analytical performance, and application methods for constructing AChE biosensors. These AChE biosensors exhibited detection limits and linearity in the ranges of 1.0×10-11 to 42.19 μM (detection limits) and 1.0×10−11–1.0×10−2 to 74.5–9.9×103μM (linearity). These biosensors were stable for a period of 2 to 120days. The future prospects for the development of better AChE biosensing systems are also discussed.
The stepwise amperometric biosensor fabrication process and immobilized acetylcholinesterase inhibition in pesticide solution.
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• Constructed a novel composite material using Fe
3O
4NP ...and c-MWCNT at Au electrode for electrocatalysis. • The properties of nanoparticles modified electrodes were studied by SEM, FTIR, CVs and EIS. • The biosensor exhibited good sensitivity (0.475
mA
μM
−1) • The half life of electrode was 2 months. • The sensor was suitable for trace detection of OP pesticide residues in milk and water.
An acetylcholinesterase (AChE) purified from maize seedlings was immobilized covalently onto iron oxide nanoparticles (Fe
3O
4NP) and carboxylated multi walled carbon nanotubes (c-MWCNT) modified Au electrode. An organophosphorus (OP) biosensor was fabricated using this AChE/Fe
3O
4/c-MWCNT/Au electrode as a working electrode, Ag/AgCl as standard and Pt wire as an auxiliary electrode connected through a potentiostat. The biosensor was based on inhibition of AChE by OP compounds/insecticides. The properties of nanoparticles modified electrodes were studied by scanning electron microscopy (SEM), Fourier transform infrared (FTIR), cyclic voltammograms (CVs) and electrochemical impedance spectroscopy (EIS). The synergistic action of Fe
3O
4NP and c-MWCNT showed excellent electrocatalytic activity at low potential (+0.4
V). The optimum working conditions for the sensor were pH 7.5, 35
°C, 600
μM substrate concentration and 10
min for inhibition by pesticide. Under optimum conditions, the inhibition rates of OP pesticides were proportional to their concentrations in the range of 0.1–40
nM, 0.1–50
nM, 1–50
nM and 10–100
nM for malathion, chlorpyrifos, monocrotophos and endosulfan respectively. The detection limits were 0.1
nM for malathion and chlorpyrifos, 1
nM for monocrotophos and 10
nM for endosulfan. The biosensor exhibited good sensitivity (0.475
mA
μM
−1), reusability (more than 50 times) and stability (2 months). The sensor was suitable for trace detection of OP pesticide residues in milk and water.
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► Constructed AChE biosensor based on AChE/Fe3O4NPs/c-MWCNT/ITO electrode. ► Enzyme electrode was characterized by AFM, FTIR, CV and EIS. ► Detection limit and working range of ...biosensor were 0.1nM and 0.1–100nM. ► Half life of enzyme electrode was 3 months. ► Biosensor measured pesticides in environmental and food samples.
A method is described for the construction of a highly sensitive electrochemical biosensor for the detection of malathion, chlorpyrifos, monocrotophos and endosulfan based on covalent immobilization of acetylcholinesterase (AChE) on iron oxide nanoparticles (Fe3O4NPs)-decorated carboxylated multi-walled carbon nanotubes (c-MWCNTs) electrodeposited onto indium tin oxide (ITO)-coated glass plate. Transmission electron microscopic (TEM) and UV analysis of nanocomposite materials demonstrated that Fe3O4NPs were well deposited on the outer walls of c-MWCNTs. The modified electrode was characterized by atomic force microscopy (AFM), cyclic voltammetry (CV), Fourier transform infrared (FTIR) spectroscopy and electrochemical impedance spectroscopy (EIS). The resulting biosensor exhibited a linear response for acetylthiocholine in a concentration range of 0.1–700μmolL−1 with a remarkable sensitivity of 0.402mA/μmolL−1. Under optimum conditions, the inhibition rates of pesticides were proportional to their concentrations in the range of 0.1–70nmolL−1, 0.1–50nmolL−1, 0.1–70nmolL−1 and 0.1–100nmolL−1 for malathion, chlorpyrifos, monocrotophos and endosulfan, respectively. The detection limit of the biosensor for all pesticides was 0.1nmolL−1 at a signal-to-noise ratio of 3. The biosensor showed good reproducibility, no interference by metal ions and long-term stability. The measurement results obtained by the present biosensor were in good agreement with those obtained by the standard gas chromatography–mass spectrometry method. The biosensor was employed for the determination of pesticides in environmental and food samples.
An amperometric uric acid biosensor was fabricated by immobilizing uricase (EC 1.7.3.3) onto gold nanoparticle (AuNP)/multiwalled carbon nanotube (MWCNT) layer deposited on Au electrode via ...carbodiimide linkage. Determination of uric acid was performed by oxidation of enzymically generated H
2O
2 at 0.4
V. The sensor showed optimal response within 7
s at 40
°C in 50
mM Tris–HCl buffer (pH 7.5). The linear working range of the biosensor was 0.01–0.8
mM. The limit of detection (LOD) was 0.01
mM. The sensor measured uric acid levels in serum of healthy individuals and persons suffering from gout. The analytical recoveries of the added uric acid, 10 and 20
mg
L
–1, were 98.0% and 96.5%, respectively. Within- and between-batch coefficients of variation were less than 5.6% and less than 4.7%, respectively. A good correlation (
r
=
0.998) was obtained between serum uric acid values by the standard enzymic colorimetric method and the current method. A number of serum substances had practically no interference. The sensor was used in more than 200 assays and had a storage life of 120
days at 4
°C.
An essential biological sensor for acetylcholine (ACh) detection is constructed by immobilizing enzymes, acetylcholinesterase (AChE) and choline oxidase (ChO), on the surface of iron oxide ...nanoparticles (Fe2O3NPs), poly(3,4-ethylenedioxythiophene) (PEDOT)-reduced graphene oxide (rGO) nanocomposite modified fluorine doped tin oxide (FTO). The qualitative and quantitative measurements of nanocomposites properties were accomplished by scanning electron microscope (SEM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). This prepared biological sensor delineated a wide linear range of 4.0nM to 800μM with a response time less than 4s and detection limit (based on S/N ratio) of 4.0nM. The sensor showed perfect sensitivity, excessive selectivity and stability for longer period of time during storage. Besides its very high-sensitivity, the biosensor has displayed a low detection limit which is reported for the first time in comparison to previously reported ACh sensors. By fabricating Fe2O3NPs/rGO/PEDOT modified FTO electrode for determining ACh level in serum samples, the applicability of biosensor has increased immensely as the detection of the level neurotransmitter is first priority for patients suffering from memory loss or Alzheimer's disease (AD).
•Fe2O3NPs/PEDOT-rGO nanocomposite film explored for acetylcholine biosensing.•Estimation of acetylcholine in serum samples of Alzheimer's patients.•Bioelectrode studied using SEM, CV and EIS and exhibit high sensitivity.
Background
Helicobacter pylori, gastric cancer‐causing bacteria, survive in their gastric environment of more than 50% of the world population. The presence of H. pylori in the gastric vicinity ...promotes the development of various diseases including peptic ulcer and gastric carcinoma. H. pylori produce and secret Vacuolating cytotoxin A (VacA), a major toxin facilitating the bacteria against the host defense system. The toxin causes multiple effects in epithelial cells and immune cells, especially T cells, B cells, and Macrophages.
Methods
This review describes the diverse functionalities of protein toxin VacA. The specific objective of this review is to address the overall structure, mechanism, and functions of VacA in various cell types. The recent advancements are summarized and discussed and thus conclusion is drawn based on the overall reported evidences.
Results
The searched articles on H. pylori VacA were evaluated and limited up to 66 articles for this review. The articles were divided into four major categories including articles on vacA gene, VacA toxin, distinct effects of VacA toxin, and their effects on various cells. Based on these studies, the review article was prepared.
Conclusions
This review describes an overview of how VacA is secreted by H. pylori and contributes to colonization and virulence in multiple ways by affecting epithelial cells, T cells, Dendritic cells, B cells, and Macrophages. The reported evidence suggests that the comprehensive outlook need to be developed for understanding distinctive functionalities of VacA.
Biosensors have acquired much importance in drug discovery, medical diagnostics, food safety, defense, security, and monitoring of environmental conditions. Furthermore, there has been great progress ...in the potential applications of advanced nanomaterials in biosensors. Every year there are several advances in sensing techniques that can be attributed to nanomaterials, biorecognition elements, or their related fabrication techniques. The further development of nanotechnology-based sensors provides a wide variety of opportunities to modern research. Advanced nanomaterials can provide remarkable optical, electrical, mechanical, and catalytic properties. For example, transition metals and organic polymers have been used in the fabrication of powerful, sensitive, and precise biosensors. The distinctive properties of advanced nanomaterials have been widely incorporated into biosensors. However, fabrication techniques also play important roles in the development of these devices. Therefore, we present a review of some of the advanced nanomaterials that have been widely used over the last few years and discuss their fabrication techniques. The focus of this review is to provide a directional perspective of recently fabricated advanced nanomaterial-based biosensors in the diagnosis of various diseases.
Calcium is a necessary biochemical messenger in neuromuscular transmission, muscle compression, and hormonal secretion processes. Calcium binds with a multifunctional intermediate calcium-binding ...sensor protein calmodulin with a significantly higher affinity. This presented work introduces an electrochemical biosensor for the detection of sepsis by utilizing calmodulin protein on the sensing interface. The sensing platform is assembled on the gold screen-printed electrode (SPE) modified with platinum nanoparticles (PtNPs) and functionalized with chitosan. Furthermore, the calmodulin protein was electrodeposited on the chitosan functionalized SPE. The electrochemical measurements were recorded for the rapid screening of Ca
2+
ions in various samples including bacterial cells and real serum samples. The serum ionized calcium is a biomarker for the detection of sepsis in newborns. The developed biosensor exhibits high sensitivity, low-cost development, and rapid results. The detection limit and sensitivity of the sensor were obtained as 1 nM and 0.51 µA/µM respectively.
Development of efficient and cost effective vaccines have been recognized as the primary concern to improve the overall healthcare in a country. In order to achieve this goal, more improved and ...powerful adjuvants need to be developed. Lacking in the self-adjuvanting immuno-modulatory constituents, vaccines exhibit lower immunogenicity. Combining potent adjuvants with vaccines is the most appropriate method to enhance the efficacy of the vaccines. Hence, this review is focussed on the most potent adjuvants for the formulation of vaccines. Areas covered: This review focuses on Oil-based emulsions, Mineral compounds, Liposomes, Bacterial products, ISCOMs and most recently used nanomaterials as adjuvants for enhancing the antigenicity of vaccines. Furthermore, this review explains the immunological response elicited by various particles. Moreover, case studies are incorporated providing an in depth analyses of various adjuvant-containing vaccines which are currently used. Expert commentary: Enhanced fundamental knowledge about the adjuvants and their immuno-stimulatory capabilities and delivery mechanisms will facilitate the rational designing of prophylactic vaccines with better efficacy.
Background: Snake bite is an established important cause of morbidity and mortality among the poor and rural population across the world including India. India accounts for the highest number of ...snakebites and related mortality globally. Objective: Identification of factors favoring the mortality due to snake bite. Methodology: A descriptive cross-sectional study was conducted from April 2022 to March 2023, and deaths due to snake bites reported from different health care facilities and community were included in the study. Results: A case-fatality rate of 5.9% due to snake bite was documented in the study. The factors identified as favorable for mortality were delayed treatment, followed by suboptimal care at primary and secondary health care facilities and traditional beliefs of the community. Conclusion: Provision of emergency service as point of care delivery, focusing on provision of training to strength point of care emergency services, co-ordination and linkages with the community members can strengthen the efforts toward reducing the mortality due to snake bites.
