Cell Membrane and V2C MXene-Based Electrochemical Immunosensor with Enhanced Antifouling Capability for Detection of CD44

Lipid Regulatory Element Interact with CD44 on Mitochondrial Bioenergetics in Bovine Adipocyte Differentiation and Lipometabolism

The CD44 gene is a critical factor in animal physiological processes and has been shown to affect insulin resistance and fat accumulation in mammals. Nevertheless, little research has been conducted on its precise functions in lipid metabolism and adipogenic differentiation in beef cattle. This study analyzed the expression of CD44 and miR-199a-3p during bovine preadipocyte differentiation. The luciferase reporter assay demonstrated that CD44 was a direct target of miR-199a-3p. Increased accumulation of lipid droplets and triglyceride levels, altered fatty acid metabolism, and accelerated preadipocyte differentiation were all caused by the upregulation of miR-199a-3p or a reduction in CD44 expression. CD44 knockdown upregulated the expression of adipocyte-specific genes (LPL and FABP4) and altered the levels of lipid metabolites (SOPC, l-arginine, and heptadecanoic acid). Multiomics highlights enriched pathways involved in energy metabolism (MAPK, cAMP, and calcium signaling) and shifts in mitochondrial respiration and glycolysis, indicating that CD44 plays a regulatory role in lipid metabolism. The findings show that intracellular lipolysis, glycolysis, mitochondrial respiration, fat deposition, and lipid droplet composition are all impacted by miR-199a-3p, which modulates CD44 in bovine adipocytes.

A novel sandwich electrochemical immunosensor utilizing customized template and phosphotungstate catalytic amplification for CD44 detection

A sandwich-type electrochemical immunosensor was proposed for the ultra-sensitive detection of CD44, a potential biomarker for breast cancer. In this design, a customized template-based ionic liquid (1-butyl-2,3-dimethylimidazolium tetrafluoroborate) carbon paste electrode (CILE) served as the sensing platform, and thionine/Au nanoparticles/covalent-organic frameworks (THI/Au/COF) were used as the signal label. Moreover, an enzyme-free signal amplification strategy was introduced by involving H2O2 and phosphotungstate (PW12) with peroxidase-like activity. Under optimized conditions, the linear range is as wide as six orders of magnitude, and the detection limit is as low as 0.71 pg mL-1 (estimated based on S/N = 3). Average recoveries range from 98.16 %-100.1 %, with a relative standard deviation (RSD) of 1.42-8.27 % in mouse serum, and from 98.44 %-99.06 %, with an RSD of 1.14-4.84 % (n = 3) in artificial saliva. Furthermore, the immunosensor exhibits excellent specificity toward CD44, good stability, and low cost, indicating great potential for application in clinical trials.

Oxygen Vacancy-Enriched CoFe2O4 for Electrochemically Sensitive Detection of the Breast Cancer CD44 Biomarker

Enhancing the selectivity of detection methods is essential to distinguish breast cancer biomarker cluster of differentiation 44 (CD44) from other species and reduce false-positive or false-negative results. Here, oxygen vacancy-enriched CoFe2O4 (CoFe2O4-x) was crafted, and its implementation as an electrochemical electrode for the detection of CD44 biomarkers has been scrutinized. This unique electrode material offers significant benefits and novel features that enhance the sensitivity and selectivity of the detection process. The oxygen vacancy density of CoFe2O4-x was tuned by adjusting the mass ratios of iron to cobalt precursors (iron-cobalt ratio) and changing annealing atmospheres. Electrochemical characterization reveals that, when the iron-cobalt ratio is 1:0.54 and the annealing atmosphere is nitrogen, the as-synthesized CoFe2O4-x electrode manifests the best electrochemical activity. The CoFe2O4-x electrode demonstrates high sensitivity (28.22 μA (ng mL)-1 cm-2), low detection limit (0.033 pg mL-1), and robust stability (for 11 days). Oxygen vacancies can not only enhance the conductivities of CoFe2O4 but also provide better adsorption of -NH2, which is beneficial for stability and electrochemical detection performance. The electrochemical detection signal can be amplified using CoFe2O4-x as a signal probe. Additionally, it is promising to know that the CoFe2O4-x electrode has shown good accuracy in real biological samples, including melanoma cell dilutions and breast cancer patient sera. The electrochemical detection results are comparable to ELISA results, which indicates that the CoFe2O4-x electrode can detect CD44 in complex biological samples. The utilization of CoFe2O4-x as the signal probe may expand the application of CoFe2O4-x in biosensing fields.

A low-fouling electrochemical biosensor based on BSA hydrogel doped with carbon black for the detection of cortisol in human serum

Electrochemical biosensors with high sensitivity can detect low concentrations of biomarkers, but their practical detection applications in complex biological environments such as human serum and sweat are severely limited by the biofouling. Herein, a conductive hydrogel based on bovine serum albumin (BSA) and conductive carbon black (CCB) was prepared for the construction of an antifouling biosensor. The BSA hydrogel (BSAG) was doped with CCB, and the prepared composite hydrogel exhibited good conductivity originated from the CCB and antifouling capability owing to the BSA hydrogel. An antifouling biosensor for the sensitive detection of cortisol was fabricated by drop-coating the conductive hydrogel onto a poly(3,4-ethylenedioxythiophene) (PEDOT) modified electrode and further immobilizing the cortisol aptamer. The constructed biosensor showed a linear range of 100 pg mL-1 - 10 μg mL-1 and a limit of detection of 26.0 pg mL-1 for the detection of cortisol, and it was capable of assaying cortisol accurately in complex human serum. This strategy of preparing antifouling and conductive hydrogels provides an effective way to develop robust electrochemical biosensors for biomarker detection in complex biological media.

Current status, challenges and prospects of antifouling materials for oncology applications

Targeted therapy has become crucial to modern translational science, offering a remedy to conventional drug delivery challenges. Conventional drug delivery systems encountered challenges related to solubility, prolonged release, and inadequate drug penetration at the target region, such as a tumor. Several formulations, such as liposomes, polymers, and dendrimers, have been successful in advancing to clinical trials with the goal of improving the drug's pharmacokinetics and biodistribution. Various stealth coatings, including hydrophilic polymers such as PEG, chitosan, and polyacrylamides, can form a protective layer over nanoparticles, preventing aggregation, opsonization, and immune system detection. As a result, they are classified under the Generally Recognized as Safe (GRAS) category. Serum, a biological sample, has a complex composition. Non-specific adsorption of chemicals onto an electrode can lead to fouling, impacting the sensitivity and accuracy of focused diagnostics and therapies. Various anti-fouling materials and procedures have been developed to minimize the impact of fouling on specific diagnoses and therapies, leading to significant advancements in recent decades. This study provides a detailed analysis of current methodologies using surface modifications that leverage the antifouling properties of polymers, peptides, proteins, and cell membranes for advanced targeted diagnostics and therapy in cancer treatment. In conclusion, we examine the significant obstacles encountered by present technologies and the possible avenues for future study and development.

Blood-Brain Barrier Penetrating Nanovehicles for Interfering with Mitochondrial Electron Flow in Glioblastoma

Glioblastoma multiforme (GBM) is the most aggressive and lethal form of human brain tumors. Dismantling the suppressed immune microenvironment is an effective therapeutic strategy against GBM; however, GBM does not respond to exogenous immunotherapeutic agents due to low immunogenicity. Manipulating the mitochondrial electron transport chain (ETC) elevates the immunogenicity of GBM, rendering previously immune-evasive tumors highly susceptible to immune surveillance, thereby enhancing tumor immune responsiveness and subsequently activating both innate and adaptive immunity. Here, we report a nanomedicine-based immunotherapeutic approach that targets the mitochondria in GBM cells by utilizing a Trojan-inspired nanovector (ABBPN) that can cross the blood-brain barrier. We propose that the synthetic photosensitizer IrPS can alter mitochondrial electron flow and concurrently interfere with mitochondrial antioxidative mechanisms by delivering si-OGG1 to GBM cells. Our synthesized ABBPN coloaded with IrPS and si-OGG1 (ISA) disrupts mitochondrial electron flow, which inhibits ATP production and induces mitochondrial DNA oxidation, thereby recruiting immune cells and endogenously activating intracranial antitumor immune responses. The results of our study indicate that strategies targeting the mitochondrial ETC have the potential to treat tumors with limited immunogenicity.

Bismuth oxide modified V2C MXene as a Schottky catalyst with enhanced photocatalytic oxidation for photo-denitration activities

In this work, a new composite photocatalyst was synthesized by flower-like Bi2O3 and two-dimensional multilayer V2C using a facile hydrothermal method. Compared with the pristine sample, the specific surface area of Bi2O3/V2C MXene composite is significantly increased, which is favourable to improve the photocatalytic efficiency. The analysis of the UV-vis absorption spectrum and band gap energy shows that the construction of heterojunction broadens the light response range, improves the light absorption capacity, and obtains a narrower band gap than any of the single component, which is beneficial to the utilization of light. PL, TPC and EIS analysis revealed that Bi2O3/V2C MXene composite had stronger carrier mobility, which further confirmed that the photocatalytic oxidation performance of the system was the dominant reason in the photocatalytic NO pollutant removal process. This study provides a new idea for better understanding the two-dimensional MXene material-based photocatalyst and improving the NO removal efficiency.

Label-free electrochemical immunosensing of glial fibrillary acidic protein (GFAP) at synthesized rGO/MoS2/AgNPs nanocomposite. Application to the determination in human cerebrospinal fluid

An electrochemical bioplatform involving screen-printed carbon electrodes modified with rGO/MoS2/AgNPs nanocomposites, the covalent immobilization of the specific capture antibody, and label-free detection has been developed for the determination of Glial Fibrillary Acidic Protein (GFAP). The resulting immunosensor profits the benefits of the rGO high conductivity, the pseudo-peroxidase activity of MoS2 and the electrocatalytic effect provided by AgNPs for improving the reduction current responses of hydrogen peroxide at the electrode surface. GFAP is a biomarker of central nervous system injuries has been proposed for the detection and monitoring of neurological diseases as epilepsy, encephalitis, or multiple sclerosis. For the first time, amperometric detection of the immunosensing event was performed by measuring the electrocatalytic response of hydrogen peroxide reduction at the modified electrode. Several techniques including scanning (SEM) and transmission (TEM) electron microscopies were used for the characterization of the synthesized composite whilst electrochemical impedance spectroscopy (EIS) using the redox probe Fe(CN)63-/4- was employed to evaluate the success of the steps implied in the fabrication of the immunosensor. After optimization of the involved experimental variables, a linear calibration plot for GFAP was constructed over the 0.6-100 ng mL-1 range, and a detection limit of 0.16 ng mL-1 was achieved. The developed immunosensor was successfully applied to the determination of GFAP in human cerebrospinal fluid (CSF) of patients diagnosed with encephalitis.

Employing nano-enabled artificial intelligence (AI)-based smart technologies for prediction, screening, and detection of cancer

Cancer has been classified as a diverse illness with a wide range of subgroups. Its early identification and prognosis, which have become a requirement of cancer research, are essential for clinical treatment. Patients have already benefited greatly from the use of artificial intelligence (AI), machine learning (ML), and deep learning (DL) algorithms in the field of healthcare. AI simulates and combines data, pre-programmed rules, and knowledge to produce predictions. Data are used to improve efficiency across several pursuits and tasks through the art of ML. DL is a larger family of ML methods based on representational learning and simulated neural networks. Support vector machines, convulsion neural networks, and artificial neural networks, among others, have been widely used in cancer research to construct prediction models that enable precise and effective decision-making. Although using these innovative methods can enhance our comprehension of how cancer progresses, further validation is required before these techniques can be used in routine clinical practice. We cover contemporary methods used in the modelling of cancer development in this article. The presented prediction models are built using a variety of guided ML approaches, as well as numerous input attributes and data collections. Early identification and cost-effective detection of cancer's progression are equally necessary for successful treatment of the disease. Smart material-based detection techniques can give end consumers a portable, affordable instrument to easily detect and monitor their health issues without the need for specialized knowledge. Owing to their cost-effectiveness, excellent sensitivity, multimodal detection capacity, and miniaturization aptitude, two-dimensional (2D) materials have a lot of prospects for clinical examination of various compounds as well as cancer biomarkers. The effectiveness of traditional devices is moving faster towards more useful techniques thanks to developments in 2D material-based biosensors/sensors. The most current developments in the design of 2D material-based biosensors/sensors-the next wave of cancer screening instruments-are also outlined in this article.

Antifouling strategies for electrochemical sensing in complex biological media

Surface fouling poses a significant challenge that restricts the analytical performance of electrochemical sensors in both in vitro and in vivo applications. Biofouling resistance is paramount to guarantee the reliable operation of electrochemical sensors in complex biofluids (e.g., blood, serum, and urine). Seeking efficient strategies for surface fouling and establishing highly sensitive sensing platforms for applications in complex media have received increasing attention in the past. In this review, we provide a comprehensive overview of recent research efforts focused on antifouling electrochemical sensors. Initially, we present a detailed illustration of the concept about biofouling along with an exploration of four key antifouling mechanisms. Subsequently, we delve into the commonly employed antifouling strategies in the fabrication of electrochemical sensors. These encompass physical surface topography (micro/nanostructure coatings and filtration membranes) and chemical surface modifications (PEG and its derivatives, zwitterionic polymers, peptides, proteins, and various other antifouling materials). The progress in antifouling electrochemical sensors is proposed concerning the antifouling mechanisms as well as sensing capability assessments (e.g., sensitivity, stability, and practical application ability). Finally, we summarize the evolving trends in the field and highlight some key remaining limitations.

MXene-based electrochemical devices applied for healthcare applications

The initial part of the review provides an extensive overview about MXenes as novel and exciting 2D nanomaterials describing their basic physico-chemical features, methods of their synthesis, and possible interfacial modifications and techniques, which could be applied to the characterization of MXenes. Unique physico-chemical parameters of MXenes make them attractive for many practical applications, which are shortly discussed. Use of MXenes for healthcare applications is a hot scientific discipline which is discussed in detail. The article focuses on determination of low molecular weight analytes (metabolites), high molecular weight analytes (DNA/RNA and proteins), or even cells, exosomes, and viruses detected using electrochemical sensors and biosensors. Separate chapters are provided to show the potential of MXene-based devices for determination of cancer biomarkers and as wearable sensors and biosensors for monitoring of a wide range of human activities.

Circulating Tumor Cells Adhesion: Application in Biosensors

The early and non-invasive diagnosis of tumor diseases has been widely investigated by the scientific community focusing on the development of sensors/biomarkers that act as a way of recognizing the adhesion of circulating tumor cells (CTCs). As a challenge in this area, strategies for CTCs capture and enrichment currently require improvements in the sensors/biomarker's selectivity. This can be achieved by understanding the biological recognition factors for different cancer cell lines and also by understanding the interaction between surface parameters and the affinity between macromolecules and the cell surface. To overcome some of these concerns, electrochemical sensors have been used as precise, fast-response, and low-cost transduction platforms for application in cytosensors. Additionally, distinct materials, geometries, and technologies have been investigated to improve the sensitivity and specificity properties of the support electrode that will transform biochemical events into electrical signals. This review identifies novel approaches regarding the application of different specific biomarkers (CD44, Integrins, and EpCAm) for capturing CTCs. These biomarkers can be applied in electrochemical biosensors as a cytodetection strategy for diagnosis of cancerous diseases.

Single-Cell Electrochemical Aptasensor Array

Despite several demonstrations of electrochemical devices with limits of detection (LOD) of 1 cell/mL, the implementation of single-cell bioelectrochemical sensor arrays has remained elusive due to the challenges of scaling up. In this study, we show that the recently introduced nanopillar array technology combined with redox-labeled aptamers targeting epithelial cell adhesion molecule (EpCAM) is perfectly suited for such implementation. Combining nanopillar arrays with microwells determined for single cell trapping directly on the sensor surface, single target cells are successfully detected and analyzed. This first implementation of a single-cell electrochemical aptasensor array, based on Brownian-fluctuating redox species, opens new opportunities for large-scale implementation and statistical analysis of early cancer diagnosis and cancer therapy in clinical settings.

Oxidase-like V2C MXene nanozyme with inherent antibacterial properties for colorimetric sensing

The microbial environment greatly affects the performance of colourimetric sensors, especially the interference of bacteria in the sample detected. This paper reports the fabrication of an antibacterial colorimetric sensor based on V₂C MXene synthesized via simple intercalation and stripping. The prepared V₂C nanosheets can mimic oxidase activity towards 3,3',5,5'-tetramethylbenzidine (TMB) oxidation without exogenously adding H₂O₂. Further mechanistic studies showed that V₂C nanosheets could effectively activate the oxygen adsorbed on their surface, which in turn causes an increase in the bond length and a decrease in the magnetic moment of oxygen through electron transfer from the nanosheet surface to O₂. The V₂C nanosheets also exhibited excellent broad-spectrum antibacterial activity through the outbreak of reactive oxygen species. Owing to its unique catalytic activity and the inherent antibacterial ability for mimicking oxidase, a colorimetric sensing platform was developed to effectively determine L-cysteine levels at a detection limit of 30.0 nM (S/N = 3). It is impressive that the detection results of L-cysteine in various complex microbial environments are also very satisfactory. This study broadens the biological use of MXene-based nanomaterials through their satisfactory enzymatic activity and provides a simple and efficient colorimetric strategy for detection techniques used in complex microbial environments.

Dual carminic acid/hemin-marked DNA probes for simultaneously detecting CV-A16 and EV-A71 based on the mechanism of dimer to monomer transition

This study aimed to prepare two hairpin-structure DNA probes by conjugating carminic acid (CA) or hemin into two ends of specific genes of coxsackievirus A16 (CV-A16) and enterovirus A71 (EV-A71) (probe_CV-A16-CA and probe_EV-A71-hemin). Then, probe_CV-A16-CA and probe_EV-A71-hemin as the signal molecules were adsorbed onto NH₂-MIL-53 (Al) (MOF). Based on these biocomposites, an electrochemical biosensor with dual-signal outputs for simultaneous assay of CV-A16 and EV-A71 was constructed. The stem-loops of probes switched both CA and hemin monomer to dimer, reducing the electrical activity of both CA and hemin. Subsequently, the target-induced opening of the stem-loop switched both CA and hemin dimers to monomers, resulting in two nonoverlapping increasing electrical signals. This sensitively reflected the concentration of target_CV-A16 and target_EV-A17 ranging from 10^-10 to 10^-15 M with a detection limit of 0.19 and 0.24 fM. This strategy was mainly applied to the simultaneous determination of target_CV-A16 and target_EV-A17 in 100% serum with satisfactory results. The MOF combined with the high loading capacity broke through the intrinsic limitation on sensitivity using the traditional methods. An increase of three orders of magnitude was observed. This study involved simple one-step detection, and only a simple replacement of a gene could trigger its potential in clinical and diagnostic applications.

Anti-Fouling Strategies of Electrochemical Sensors for Tumor Markers

The early detection and prognosis of cancers require sensitive and accurate detection methods; with developments in medicine, electrochemical biosensors have been developed that can meet these clinical needs. However, the composition of biological samples represented by serum is complex; when substances undergo non-specific adsorption to an electrode and cause fouling, the sensitivity and accuracy of the electrochemical sensor are affected. In order to reduce the effects of fouling on electrochemical sensors, a variety of anti-fouling materials and methods have been developed, and enormous progress has been made over the past few decades. Herein, the recent advances in anti-fouling materials and strategies for using electrochemical sensors for tumor markers are reviewed; we focus on new anti-fouling methods that separate the immunorecognition and signal readout platforms.

A Comprehensive Review on Electrochemical Nano Biosensors for Precise Detection of Blood-Based Oncomarkers in Breast Cancer

Breast cancer (BC), one of the most common and life-threatening cancers, has the highest incidence rate among women. Early diagnosis of BC oncomarkers is considered the most effective strategy for detecting and treating BC. Finding the type and stage of BC in women as soon as possible is one of the greatest ways to stop its incidence and negative effects on medical treatment. The development of biosensors for early, sensitive, and selective detection of oncomarkers has recently attracted much attention. An electrochemical nano biosensor (EN) is a very suitable option for a powerful tool for cancer diagnosis. This comprehensive review provides information about the prevalence and pathobiology of BC, recent advances in clinically available BC oncomarkers, and the most common electrochemical nano biosensors for point-of-care (POC) detection of various BC oncomarkers using nanomaterial-based signal amplification techniques.

Emerging Trends and Recent Progress of MXene as a Promising 2D Material for Point of Care (POC) Diagnostics

Two-dimensional (2D) nanomaterials with chemical and structural diversity have piqued the interest of the scientific community due to their superior photonic, mechanical, electrical, magnetic, and catalytic capabilities that distinguish them from their bulk counterparts. Among these 2D materials, two-dimensional (2D) transition metal carbides, carbonitrides, and nitrides with a general chemical formula of M_n+1X_nT_x (where n = 1-3), together known as MXenes, have gained tremendous popularity and demonstrated competitive performance in biosensing applications. In this review, we focus on the cutting-edge advances in MXene-related biomaterials, with a systematic summary on their design, synthesis, surface engineering approaches, unique properties, and biological properties. We particularly emphasize the property-activity-effect relationship of MXenes at the nano-bio interface. We also discuss the recent trends in the application of MXenes in accelerating the performance of conventional point of care (POC) devices towards more practical approaches as the next generation of POC tools. Finally, we explore in depth the existing problems, challenges, and potential for future improvement of MXene-based materials for POC testing, with the goal of facilitating their early realization of biological applications.

Conductive Antifouling Sensing Coating: A Bionic Design Inspired by Natural Cell Membrane

Constructing antifouling coatings for biosensing interfaces is a major hurdle in driving their practical application. Inspired by the excellent antifouling properties of natural cell membranes, a conductive biomimetic antifouling interface coating is proposed, which highly mimics the excellent antifouling properties of biofilms while overcoming the low conductivity defects of conventional coatings. Polyethylene glycol-Au gel is selected as the support structure and electron transfer layer, on which phospholipids and ampholytes are applied to construct a hydration layer for antifouling. The coating maintains promisingly low adsorption in biological matrices such as whole blood, serum, and urine, and has been utilized to construct multimodal clinical assay systems that provide favorable concordance with clinical results. Thus, this conductive bio-coating breaks the last barrier of biosensors toward practical applications and possesses extremely significant application value.