Comparative Study of Electrochemical Biosensors Based on Highly Efficient Mesoporous ZrO2-Ag-G-SiO2 and In2O3-G-SiO2 for Rapid Recognition of E. coli O157:H7

Nanomaterial-based methods for sepsis management

Sepsis is a serious disease caused by an impaired host immune response to infection, resulting in organ dysfunction, tissue damage and is responsible for high in-hospital mortality (approximately 20%). Recently, WHO documented sepsis as a global health priority. Nevertheless, there is still no effective and specific therapy for clinically detecting sepsis. Nanomaterial-based approaches have appeared as promising tools for identifying bacterial infections. In this review, recent biosensors are introduced and summarized as nanomaterial-based platforms for sepsis management and severe complications. Biosensors can be used as tools for the diagnosis and treatment of sepsis and as nanocarriers for drug delivery. In general, diagnostic methods for sepsis-associated bacteria, biosensors developed for this purpose are presented in detail, and their strengths and weaknesses are discussed. In other words, readers of this article will gain a comprehensive understanding of biosensors and their applications in sepsis management.

Biomedical Applications of Zirconia-Based Nanomaterials: Challenges and Future Perspectives

ZrO₂ nanoparticles have received substantially increased attention in every field of life owing to their wide range of applications. Zirconium oxide is a commercially economical, non-hazardous, and sustainable metal oxide having diversified potential applications. ZrO₂ NPs play a vast role in the domain of medicine and pharmacy such as anticancer, antibacterial, and antioxidant agents and tissue engineering owing to their reliable curative biomedical applications. In this review article, we address all of the medical and biomedical applications of ZrO₂ NPs prepared through various approaches in a critical way. ZrO₂ is a bio-ceramic substance that has received increased attention in biomimetic scaffolds owing to its high mechanical strength, excellent biocompatibility, and high chemical stability. ZrO₂ NPs have demonstrated potential anticancer activity against various cancer cells. ZrO₂-based nanomaterials have exhibited potential antibacterial activity against various bacterial strains and have also demonstrated excellent antioxidant activity. The ZrO₂ nanocomposite also exhibits highly sensitive biosensing activity toward the sensing of glucose and other biological species.

Low-cost goldleaf electrode as a platform for Escherichia coli immunodetection

Gold electrodes are one of most prevalent substrates in electrochemical biosensors because they can be easily and highly efficiently functionalized with thiolated biomolecules. However, conventional methods to fabricate gold electrodes are costly, time-consuming and require onerous equipment. Here, an affordable method for rapid fabrication of an electrochemical immunosensor for Escherichia coli detection is presented. The gold electrode was generated using 24-karat gold leaves and lowcost polyvinyl chloride adhesive sheets covered with an insulating PTFE layer. The goldleaf electrode (GLE) was patterned using laser ablation and characterized by cyclic voltammetry, electrochemical impedance spectroscopy, scanning electronic microscopy, contact angle and 3D profiling. The GLEs were modified by a self-assembled mercaptopropionic monolayer, followed by surface activation to allow binding of the specific anti-E. coli antibody via carbodiimide linking. The biosensor showed a detection limit of 2 CFU/mL and a linear dynamic range of 10-10⁷ CFU/mL for E. coli cells. No false positive signals were obtained from control bacteria. The obtained results demonstrated suitability of GLE for use in biosensors with high reliability and reproducibility. It is foreseeable that our work will inspire design of point-of-need biosensors broadly applicable in low-resource settings.

3D Modeling of Silver Doped ZrO2 Coupled Graphene-Based Mesoporous Silica Quaternary Nanocomposite for a Nonenzymatic Glucose Sensing Effects

We described the novel nanocomposite of silver doped ZrO2 combined graphene-based mesoporous silica (ZrO2-Ag-G-SiO2,) in bases of low-cost and self-assembly strategy. Synthesized ZrO2-Ag-G-SiO2 were characterized through X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDX), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, Nitrogen adsorption-desorption isotherms, X-ray photoelectron spectroscopy (XPS), and Diffuse Reflectance Spectroscopy (DRS). The ZrO2-Ag-G-SiO2 as an enzyme-free glucose sensor active material toward coordinate electro-oxidation of glucose was considered through cyclic voltammetry in significant electrolytes, such as phosphate buffer (PBS) at pH 7.4 and commercial urine. Utilizing ZrO2-Ag-G-SiO2, glucose detecting may well be finished with effective electrocatalytic performance toward organically important concentrations with the current reaction of 9.0 × 10-3 mAcm-2 and 0.05 mmol/L at the lowest potential of +0.2 V, thus fulfilling the elemental prerequisites for glucose detecting within the urine. Likewise, the ZrO2-Ag-G-SiO2 electrode can be worked for glucose detecting within the interferometer substances (e.g., ascorbic corrosive, lactose, fructose, and starch) in urine at proper pH conditions. Our results highlight the potential usages for qualitative and quantitative electrochemical investigation of glucose through the ZrO2-Ag-G-SiO2 sensor for glucose detecting within the urine concentration.

A flexible mesoporous Cu doped FeSn–G–SiO2 composite based biosensor for microalbumin detection

A new mesoporous Cu-doped FeSn–G–SiO₂ (CFSGS) based biosensor was developed for the detection of microalbumin in urine samples. The mechanically flexible FeSn modified sensor was fabricated at room temperature. These demonstrations highlight the unexplored potential of FeSn for developing novel biosensing devices. It is extremely sensitive and selective. Surfactant-aided self-assembly was used to synthesise the mesoporous CFSGS. The large surface area due to the mesopore presence in the CFSG surface that has been composited inside the mesoporous SiO₂ boosted the electrochemical detection. The linear range and detection limit of microalbumin under optimum circumstances were 0.42 and 1 to 10 μL, respectively. This easily fabricated mesoporous CFSGS provided a fast response with high sensitivity, and good selectivity. The sensor's reusability and repeatability were also quite high, with just a 90 percent drop after 4 weeks of storage at ambient temperature. The biosensor also demonstrated high selectivity against typical potential interfering chemicals found in urine (ascorbic acid, urea, and sodium chloride). The good performance of the mesoporous CFSGS biosensor was validated by measuring microalbumin, and the findings indicated that this sensing device performed very well.

Microalbumin sensing mechanism with electrochemical performance system.

Probing the emission dynamics in nitrogen doped carbon dots by reversible capping with mercury (II) through surface chemistry

In this study, the mechanistic insight and emission dynamics have been explored of size dependent nitrogen doped carbon quantum dots (namely 3A,3B & 3C) with toxic metal Hg2+ ions via...

Advances in Nanomaterials-Based Electrochemical Biosensors for Foodborne Pathogen Detection

Electrochemical biosensors utilizing nanomaterials have received widespread attention in pathogen detection and monitoring. Here, the potential of different nanomaterials and electrochemical technologies is reviewed for the development of novel diagnostic devices for the detection of foodborne pathogens and their biomarkers. The overview covers basic electrochemical methods and means for electrode functionalization, utilization of nanomaterials that include quantum dots, gold, silver and magnetic nanoparticles, carbon nanomaterials (carbon and graphene quantum dots, carbon nanotubes, graphene and reduced graphene oxide, graphene nanoplatelets, laser-induced graphene), metal oxides (nanoparticles, 2D and 3D nanostructures) and other 2D nanomaterials. Moreover, the current and future landscape of synergic effects of nanocomposites combining different nanomaterials is provided to illustrate how the limitations of traditional technologies can be overcome to design rapid, ultrasensitive, specific and affordable biosensors.

Modern Analytical Techniques for Detection of Bacteria in Surface and Wastewaters

Contamination of surface waters with pathogens as well as all diseases associated with such events are a significant concern worldwide. In recent decades, there has been a growing interest in developing analytical methods with good performance for the detection of this category of contaminants. The most important analytical methods applied for the determination of bacteria in waters are traditional ones (such as bacterial culturing methods, enzyme-linked immunoassay, polymerase chain reaction, and loop-mediated isothermal amplification) and advanced alternative methods (such as spectrometry, chromatography, capillary electrophoresis, surface-enhanced Raman scattering, and magnetic field-assisted and hyphenated techniques). In addition, optical and electrochemical sensors have gained much attention as essential alternatives for the conventional detection of bacteria. The large number of available methods have been materialized by many publications in this field aimed to ensure the control of water quality in water resources. This study represents a critical synthesis of the literature regarding the latest analytical methods covering comparative aspects of pathogen contamination of water resources. All these aspects are presented as representative examples, focusing on two important bacteria with essential implications on the health of the population, namely Pseudomonas aeruginosa and Escherichia coli.

A robust electrochemical immunosensor based on core-shell nanostructured silica-coated silver for cancer (carcinoembryonic-antigen-CEA) diagnosis

This work addresses the fabrication of an efficient, novel, and economically viable immunosensing armamentarium that will detect the carcinoembryonic antigen (CEA) typically associated with solid tumors (sarcomas, carcinomas, and lymphomas) and is used as a clinical tumor marker for all these malignancies. We synthesized silver nanoparticles by single-step chemical reduction and coated with silica using a modified Stober method to fabricate silica-coated silver core-shell nanoparticles. The morphologies, structure, and size of the nanoparticles were characterized by Transmission Electron Microscopy (TEM), UV-Visible spectroscopy, X-ray diffraction (XRD), Raman spectroscopy, Fourier Transform Infra-Red Spectroscopy (FTIR), and Dynamic Light Scattering (DLS), respectively. The results indicated that the average size of Ag nanoparticles and silica-coated Ag nanoparticles is 50 nm and 80 nm, respectively. Our TEM results indicate that the silica-shell uniformly encapsulates silver core particles. Further, a disposable electrochemical immunosensor for carcinoembryonic antigen (CEA) was proposed based on the antigen immobilized in a silica-coated silver core-shell nanoparticle film on the surface of an indium-tin-oxide (ITO) flat substrate. The morphological characteristics of the constructed biosensor were observed by scanning electron microscopy (SEM) and electrochemical methods. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were employed for the characterization of the proposed bioelectrode. The cyclic voltammogram appears to be more irreversible on silica coated silver core-shell nanoparticles. It is found that the fabricated immunosensor shows fast potentiometric response under the optimized conditions. The CEA could be determined in the linear range from 0.5 to 10 ng mL-1 with a detection limit of 0.01 ng mL-1 using the interface. The developed flat substrate of ITO for CEA detection (the model reagent) is a potentially promising immunosensing system, manifests good stability, and allows batch fabrication because of its economic feasibility.