Graphene Doped Mn2 O3 Nanofibers as a Facile Electroanalytical DNA Point Mutation Detection Platform for Early Diagnosis of Breast/Ovarian Cancer

Toll-like receptor-immobilized carbon paste electrodes with plasma functionalized amine termination: Towards real-time electrochemical based triaging of gram-negative bacteria

Chronic wounds caused due to bacterial biofilms are detrimental to a patient, and an immediate diagnosis of these bacteria can aid in an effective treatment, which is still an unmet clinical need. An instant and accurate identification of bacterial type could be made by utilizing the Toll-Like Receptors (TLRs) combined with Myeloid Differentiation factor 2 (MD-2). Given this, we have developed an electrochemical sensing platform to identify the gram-negative (gram-ve) bacteria using TLR4/MD-2 complex. The nonthermal plasma (NTP) technique was utilized to functionalize amine groups onto the carbon surface to fabricate cost-effective carbon paste working electrodes (CPEs). The proposed electrochemical sensor platform with a specially engineered electrochemical cell (E-Cell) identified the Escherichia coli (E. coli) in a wide linear range of 1.5×10° - 1.5×106 C.F.U./mL, accounting for a very low detection limit of 0.087 C.F.U./mL. The novel and cost-effective sensor platform identified gram-ve bacteria predominantly in a mixture of gram positive (gram+ve) bacteria and fungi. Further, towards real-time detection of bacteria and point-of-care (PoC) applications, the effect of the pond water matrix was studied, which was minimal, and the sensor could identify E. coli concentrations selectively, showing the potential application of the proposed platform towards real-time bacterial detection.

Device-Physics Realization of ZnO-MWCNT Nanostructure-Based Field-Effect Biosensor for Ultrasensitive Simultaneous Genomic Detection of Foodborne Pathogens

The complex and versatile interactions among the wide variety of the nanostructures and the target analytes have primarily limited the detailed investigation of the transduction mechanism of nanomaterial-assisted electrical signal-based biosensors despite their high sensitivity, low-cost, portability, and ease of deployment. Hence, no common ground is formed detailing the principle of operation, demanding a strong need for systematic examination instead of hit and trial. Therefore, a maiden mechanistic investigation has been carried out in this paper for a field-effect-based biosensor device relying on the energy band diagram and the surface potential profile. To demonstrate the experimental evidence and appreciate the importance of food safety, three hazardous foodborne pathogens (Proteus mirabilis, Escherichia coli, and Clostridium botulinum) have been detected herein. The biosensor device, built on a hydrothermally synthesized zinc oxide and MWCNT (ZnO-MWCNT) composite nanostructure, simultaneously incorporates three fairly specific ss-DNA probes. Furthermore, the unmet challenge of biosensor device variability is addressed through the optimum selection of operating voltage of the device via a unique "voltage-selection-algorithm". We believe that the rigorous experimentation and the insightful device-physics realization demonstrated in this work will pave the way for a future decisive biosensor platform.

Integration of 3D Printing-Coelectrospinning: Concept Shifting in Biomedical Applications

Porous structures with sizes between the submicrometer and nanometer scales can be produced using efficient and adaptable electrospinning technology. However, to approximate desirable structures, the construction lacks mechanical sophistication and conformance and requires three-dimensional solitary or multifunctional structures. The diversity of high-performance polymers and blends has enabled the creation of several porous structural conformations for applications in advanced materials science, particularly in biomedicine. Two promising technologies can be combined, such as electrospinning with 3D printing or additive manufacturing, thereby providing a straightforward yet flexible technique for digitally controlled shape-morphing fabrication. The hierarchical integration of configurations is used to imprint complex shapes and patterns onto mesostructured, stimulus-responsive electrospun fabrics. This technique controls the internal stresses caused by the swelling/contraction mismatch in the in-plane and interlayer regions, which, in turn, controls the morphological characteristics of the electrospun membranes. Major innovations in 3D printing, along with additive manufacturing, have led to the production of materials and scaffold systems for tactile and wearable sensors, filtration structures, sensors for structural health monitoring, tissue engineering, biomedical scaffolds, and optical patterning. This review discusses the synergy between 3D printing and electrospinning as a constituent of specific microfabrication methods for quick structural prototypes that are expected to advance into next-generation constructs. Furthermore, individual techniques, their process parameters, and how the fabricated novel structures are applied holistically in the biomedical field have never been discussed in the literature. In summary, this review offers novel insights into the use of electrospinning and 3D printing as well as their integration for cutting-edge applications in the biomedical field.

Nano-biosensor for SARS-CoV-2/COVID-19 detection: methods, mechanism and interface design

The epidemic of coronavirus disease 2019 (COVID-19) was a huge disaster to human society. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which led to COVID-19, has resulted in a large number of deaths. Even though the reverse transcription-polymerase chain reaction (RT-PCR) is the most efficient method for the detection of SARS-CoV-2, the disadvantages (such as long detection time, professional operators, expensive instruments, and laboratory equipment) limit its application. In this review, the different kinds of nano-biosensors based on surface-enhanced Raman scattering (SERS), surface plasmon resonance (SPR), field-effect transistor (FET), fluorescence methods, and electrochemical methods are summarized, starting with a concise description of their sensing mechanism. The different bioprobes (such as ACE2, S protein-antibody, IgG antibody, IgM antibody, and SARS-CoV-2 DNA probes) with different bio-principles are introduced. The key structural components of the biosensors are briefly introduced to give readers an understanding of the principles behind the testing methods. In particular, SARS-CoV-2-related RNA mutation detection and its challenges are also briefly described. We hope that this review will encourage readers with different research backgrounds to design SARS-CoV-2 nano-biosensors with high selectivity and sensitivity.

A Sequential Electrospinning of a Coaxial and Blending Process for Creating Double-Layer Hybrid Films to Sense Glucose

This study presents a glucose biosensor based on electrospun core-sheath nanofibers. Two types of film were fabricated using different electrospinning procedures. Film F1 was composed solely of core-sheath nanofibers fabricated using a modified coaxial electrospinning process. Film F2 was a double-layer hybrid film fabricated through a sequential electrospinning and blending process. The bottom layer of F2 comprised core-sheath nanofibers fabricated using a modified process, in which pure polymethacrylate type A (Eudragit L100) was used as the core section and water-soluble lignin (WSL) and phenol were loaded as the sheath section. The top layer of F2 contained glucose oxidase (GOx) and gold nanoparticles, which were distributed throughout the polyvinylpyrrolidone K90 (PVP K90) nanofibers through a single-fluid blending electrospinning process. The study investigated the sequential electrospinning process in detail. The experimental results demonstrated that the F2 hybrid film had a higher degradation efficiency of β-D-glucose than F1, reaching a maximum of over 70% after 12 h within the concentration range of 10-40 mmol/L. The hybrid film F2 is used for colorimetric sensing of β-D-glucose in the range of 1-15 mmol/L. The solution exhibited a color that deepened gradually with an increase in β-D-glucose concentration. Electrospinning is flexible in creating structures for bio-cascade reactions, and the double-layer hybrid film can provide a simple template for developing other sensing nanomaterials.

Electrochemical biosensors for analysis of DNA point mutations in cancer research

Cancer is a genetic disease induced by mutations in DNA, in particular point mutations in important driver genes that lead to protein malfunctioning and ultimately to tumorigenesis. Screening for the most common DNA point mutations, especially in such genes as TP53, BRCA1 and BRCA2, EGFR, KRAS, or BRAF, is crucial to determine predisposition risk for cancer or to predict response to therapy. In this review, we briefly depict how these genes are involved in cancer, followed by a description of the most common techniques routinely applied for their analysis, including high-throughput next-generation sequencing technology and less expensive low-throughput options, such as real-time PCR, restriction fragment length polymorphism, or high resolution melting analysis. We then introduce benefits of electrochemical biosensors as interesting alternatives to the standard methods in terms of cost, speed, and simplicity. We describe most common strategies involved in electrochemical biosensing of point mutations, relying mostly on PCR or isothermal amplification techniques, and critically discuss major challenges and obstacles that, until now, prevented their more widespread application in clinical settings.

The Application of Carbon Nanomaterials in Sensing, Imaging, Drug Delivery and Therapy for Gynecologic Cancers: An Overview

Gynecologic cancers are one of the main health concerns of women throughout the world, and the early diagnosis and effective therapy of gynecologic cancers will be particularly important for the survival of female patients. As a current hotspot, carbon nanomaterials have attracted tremendous interest in tumor theranostics, and their application in gynecologic cancers has also been developed rapidly with great achievements in recent years. This Overview Article summarizes the latest progress in the application of diverse carbon nanomaterials (e.g., graphenes, carbon nanotubes, mesoporous carbon, carbon dots, etc.) and their derivatives in the sensing, imaging, drug delivery, and therapy of different gynecologic cancers. Important research contributions are highlighted in terms of the relationships among the fabrication strategies, architectural features, and action mechanisms for the diagnosis and therapy of gynecologic cancers. The current challenges and future strategies are discussed from the viewpoint of the real clinical application of carbon-based nanomedicines in gynecologic cancers. It is anticipated that this review will attract more attention toward the development and application of carbon nanomaterials for the theranostics of gynecologic cancers.

Utilizing Electrochemical-Based Sensing Approaches for the Detection of SARS-CoV-2 in Clinical Samples: A Review

The development of precise and efficient diagnostic tools enables early treatment and proper isolation of infected individuals, hence limiting the spread of coronavirus disease 2019 (COVID-19). The standard diagnostic tests used by healthcare workers to diagnose severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection have some limitations, including longer detection time, the need for qualified individuals, and the use of sophisticated bench-top equipment, which limit their use for rapid SARS-CoV-2 assessment. Advances in sensor technology have renewed the interest in electrochemical biosensors miniaturization, which provide improved diagnostic qualities such as rapid response, simplicity of operation, portability, and readiness for on-site screening of infection. This review gives a condensed overview of the current electrochemical sensing platform strategies for SARS-CoV-2 detection in clinical samples. The fundamentals of fabricating electrochemical biosensors, such as the chosen electrode materials, electrochemical transducing techniques, and sensitive biorecognition molecules, are thoroughly discussed in this paper. Furthermore, we summarised electrochemical biosensors detection strategies and their analytical performance on diverse clinical samples, including saliva, blood, and nasopharyngeal swab. Finally, we address the employment of miniaturized electrochemical biosensors integrated with microfluidic technology in viral electrochemical biosensors, emphasizing its potential for on-site diagnostics applications.

Deciphering the role of nanostructured materials in the point-of-care diagnostics for COVID-19: a comprehensive review

The infamous COVID-19 outbreak has left a crippling impact on the economy, healthcare infrastructure, and lives of the general working class, with all the scientists determined to find suitable and efficient diagnostic techniques and therapies to contain its ramifications. This article presents the complete outline of the diagnostic platforms developed using nanoparticles in the detection of SARS-CoV-2, delineating the direct and indirect use of nanomaterials in COVID-19 diagnosis. The properties of nanostructured materials and their relevance in the development of novel point-of-care diagnostic approaches for COVID-19 are highlighted. More importantly, the advantages of nanotechnologies over conventional reverse transcriptase-polymerase chain reaction technique and few other methods used in the detection of SARS-CoV-2 along with the viewpoints are discussed. Also, the future perspectives highlighting the commercial aspects of the nanotechnology-based diagnostic tools developed to combat the COVID-19 pandemic are presented.

Emerging point-of-care biosensors for rapid diagnosis of COVID-19: current progress, challenges, and future prospects

Coronavirus disease 2019 (COVID-19) pandemic is currently a serious global health threat. While conventional laboratory tests such as quantitative real-time polymerase chain reaction (qPCR), serology tests, and chest computerized tomography (CT) scan allow diagnosis of COVID-19, these tests are time-consuming and laborious, and are limited in resource-limited settings or developing countries. Point-of-care (POC) biosensors such as chip-based and paper-based biosensors are typically rapid, portable, cost-effective, and user-friendly, which can be used for COVID-19 in remote settings. The escalating demand for rapid diagnosis of COVID-19 presents a strong need for a timely and comprehensive review on the POC biosensors for COVID-19 that meet ASSURED criteria: Affordable, Sensitive, Specific, User-friendly, Rapid and Robust, Equipment-free, and Deliverable to end users. In the present review, we discuss the importance of rapid and early diagnosis of COVID-19 and pathogenesis of COVID-19 along with the key diagnostic biomarkers. We critically review the most recent advances in POC biosensors which show great promise for the detection of COVID-19 based on three main categories: chip-based biosensors, paper-based biosensors, and other biosensors. We subsequently discuss the key benefits of these biosensors and their use for the detection of antigen, antibody, and viral nucleic acids. The commercial POC biosensors for COVID-19 are critically compared. Finally, we discuss the key challenges and future perspectives of developing emerging POC biosensors for COVID-19. This review would be very useful for guiding strategies for developing and commercializing rapid POC tests to manage the spread of infections.Graphical abstract.

Label-Free Electrochemical Detection of DNA Hybridization: A Method for COVID-19 Diagnosis

This paper presents label-free electrochemical transduction as a suitable scheme for COVID-19-specific viral RNA/c-DNA detection, with an aim to facilitate point of care diagnosis. In lieu of this, we discuss the proposed electrochemical biosensing scheme, based on electrodeposited gold nanoparticles as the transducing elements. Specific to this approach, here, the protocols associated with the immobilization of the single-stranded probe nucleotide on to the biosensor, have also been laid out. This paper also discusses the methods of electrochemical analysis, to be used for data acquisition and subsequent calibration, in relation to target analyte detection. Towards facilitating portable diagnosis, development of miniaturized sensors and their integration with readout units have also been discussed.

A miniaturized electrochemical platform with an integrated PDMS reservoir for label-free DNA hybridization detection using nanostructured Au electrodes

We report the fabrication and characterization of a miniaturized electrochemical platform for the label-free detection of DNA hybridization. The proposed platform is fabricated using microfabrication and electrodeposition techniques. Comprising a Ti working electrode with electrodeposited Au nanostructures, and Pt/Au pseudo-reference and counter electrodes, the device accounts for a limit of detection of 0.97 fM and a sensitivity of 20.78 (μA μM-1) cm-2 with respect to Dengue virus specific consensus primer detection in the range of 10 fM-1 μM. Here, the incorporation of nanostructured Au in the active sensing area not only enhances the current response by increasing the overall surface area, but it also facilitates facile probe DNA immobilization by gold-thiol self-assembly. We have used differential pulse voltammetry analysis in this study to monitor the changes in reaction kinetics with respect to target hybridization. Furthermore, the evaluation of reproducibility of the biosensor and its selectivity against interference has yielded acceptable outcomes. Additionally, in order to evaluate the system's selectivity, we have successfully distinguished PCR amplified wild type and mutant target DNAs corresponding to the BRCA1 specific gene. Here, the mutant and the wild type target DNAs differ by a two base deletion, and the fact that the system is able to differentiate even such minute dissimilarities under hybridization conditions is indicative of its superior performance.