Biosensors for cancer markers diagnosis

Electrochemical biosensors for early detection of breast cancer

Breast cancer continues to be a significant contributor to global cancer deaths, particularly among women. This highlights the critical role of early detection and treatment in boosting survival rates. While conventional diagnostic methods like mammograms, biopsies, ultrasounds, and MRIs are valuable tools, limitations exist in terms of cost, invasiveness, and the requirement for specialized equipment and trained personnel. Recent shifts towards biosensor technologies offer a promising alternative for monitoring biological processes and providing accurate health diagnostics in a cost-effective, non-invasive manner. These biosensors are particularly advantageous for early detection of primary tumors, metastases, and recurrent diseases, contributing to more effective breast cancer management. The integration of biosensor technology into medical devices has led to the development of low-cost, adaptable, and efficient diagnostic tools. In this framework, electrochemical screening platforms have garnered significant attention due to their selectivity, affordability, and ease of result interpretation. The current review discusses various breast cancer biomarkers and the potential of electrochemical biosensors to revolutionize early cancer detection, making provision for new diagnostic platforms and personalized healthcare solutions.

Recent Progress in Organic Electrochemical Transistor-Structured Biosensors

The continued advancement of organic electronic technology will establish organic electrochemical transistors as pivotal instruments in the field of biological detection. Here, we present a comprehensive review of the state-of-the-art technology and advancements in the use of organic electrochemical transistors as biosensors. This review provides an in-depth analysis of the diverse modification materials, methods, and mechanisms utilized in organic electrochemical transistor-structured biosensors (OETBs) for the selective detection of a wide range of target analyte encompassing electroactive species, electro-inactive species, and cancer cells. Recent advances in OETBs for use in sensing systems and wearable and implantable applications are also briefly introduced. Finally, challenges and opportunities in the field are discussed.

Biosensors for Cancer Biomarkers Based on Mesoporous Silica Nanoparticles

Mesoporous silica nanoparticles (MSNs) exhibit highly beneficial characteristics for devising efficient biosensors for different analytes. Their unique properties, such as capabilities for stable covalent binding to recognition groups (e.g., antibodies or aptamers) and sensing surfaces, open a plethora of opportunities for biosensor construction. In addition, their structured porosity offers capabilities for entrapping signaling molecules (dyes or electroactive species), which could be released efficiently in response to a desired analyte for effective optical or electrochemical detection. This work offers an overview of recent research studies (in the last five years) that contain MSNs in their optical and electrochemical sensing platforms for the detection of cancer biomarkers, classified by cancer type. In addition, this study provides an overview of cancer biomarkers, as well as electrochemical and optical detection methods in general.

Transistor-based immunosensor using AuNPs-Ab2-HRP enzyme nanoprobe for the detection of antigen biomarker in human blood

Alpha-fetoprotein (AFP) is inextricably linked to various diseases, including liver cancer. Thus, detecting the content of AFP in biology has great significance in diagnosis, treatment, and intervention. Motivated by the urgent need for affordable and convenient electronic sensors in the analysis and detection of aqueous biological samples, we combined the solution-gated graphene transistor (SGGT) with the catalytic reaction of enzyme nanoprobes (HRP-AuNPs-Ab2) to accurately sense AFP. The SGGT immunosensor demonstrated high specificity and stability, excellent selectivity, and excessive linearity over a range of 4 ng/mL to 500 ng/mL, with the lower detection limit down to 1.03 ng/mL. Finally, clinical samples were successfully detected by the SGGT immunosensor, and the results were consistent with chemiluminescence methods that are popular in hospitals for detecting AFP. Notably, the SGGT immunosensor is also recyclable, so it has excellent potential for use in high-throughput detection.

MicroRNA biosensors in lung cancer

Lung cancer has been one of the leading causes of death over the past century. Unfortunately, the reliance on conventional methods to diagnose the phenotypic properties of tumors hinders early-stage cancer diagnosis. However, recent advancements in identifying disease-specific nucleotide biomarkers, particularly microRNAs, have brought us closer to early-stage detection. The roles of miR-155, miR-197, and miR-182 have been established in stage I lung cancer. Recent progress in synthesizing nanomaterials with higher conductivity has enhanced the diagnostic sensitivity of electrochemical biosensors, which can detect low concentrations of targeted biomarkers. Therefore, this review article focuses on exploring electrochemical biosensors based on microRNA in lung cancer.

Applications of Pyrrole and Pyridine-based Heterocycles in Cancer Diagnosis and Treatment

BACKGROUND

The escalation of cancer worldwide is one of the major causes of economy burden and loss of human resources. According to the American Cancer Society, there will be 1,958,310 new cancer cases and 609,820 projected cancer deaths in 2023 in the United States. It is projected that by 2040, the burden of global cancer is expected to rise to 29.5 million per year, causing a death toll of 16.4 million. The hemostasis regulation by cellular protein synthesis and their targeted degradation is required for normal cell growth. The imbalance in hemostasis causes unbridled growth in cells and results in cancer. The DNA of cells needs to be targeted by chemotherapeutic agents for cancer treatment, but at the same time, their efficacy and toxicity also need to be considered for successful treatment.

OBJECTIVE

The objective of this study is to review the published work on pyrrole and pyridine, which have been prominent in the diagnosis and possess anticancer activity, to obtain some novel lead molecules of improved cancer therapeutic.

METHODS

A literature search was carried out using different search engines, like Sci-finder, Elsevier, ScienceDirect, RSC etc., for small molecules based on pyrrole and pyridine helpful in diagnosis and inducing apoptosis in cancer cells. The research findings on the application of these compounds from 2018-2023 were reviewed on a variety of cell lines, such as breast cancer, liver cancer, epithelial cancer, etc. Results: In this review, the published small molecules, pyrrole and pyridine and their derivatives, which have roles in the diagnosis and treatment of cancers, were discussed to provide some insight into the structural features responsible for diagnosis and treatment. The analogues with the chromeno-furo-pyridine skeleton showed the highest anticancer activity against breast cancer. The compound 5-amino-N-(1-(pyridin-4- yl)ethylidene)-1H-pyrazole-4-carbohydrazides was highly potent against HEPG2 cancer cell. Redaporfin is used for the treatment of cholangiocarcinoma, biliary tract cancer, cisplatin-resistant head and neck squamous cell carcinoma, and pigmentation melanoma, and it is in clinical trials for phase II. These structural features present a high potential for designing novel anticancer agents for diagnosis and drug development.

CONCLUSION

Therefore, the N- and C-substituted pyrrole and pyridine-based novel privileged small Nheterocyclic scaffolds are potential molecules used in the diagnosis and treatment of cancer. This review discusses the reports on the synthesis of such molecules during 2018-2023. The review mainly discusses various diagnostic techniques for cancer, which employ pyrrole and pyridine heterocyclic scaffolds. Furthermore, the anticancer activity of N- and C-substituted pyrrole and pyridine-based scaffolds has been described, which works against different cancer cell lines, such as MCF-7, A549, A2780, HepG2, MDA-MB-231, K562, HT- 29, Caco-2 cells, Hela, Huh-7, WSU-DLCL2, HCT-116, HBL-100, H23, HCC827, SKOV3, etc. This review will help the researchers to obtain a critical insight into the structural aspects of pyrrole and pyridine-based scaffolds useful in cancer diagnosis as well as treatment and design pathways to develop novel drugs in the future.

Hair and Nail-On-Chip for Bioinspired Microfluidic Device Fabrication and Biomarker Detection

The advent of biosensors has tremendously increased our potential of identifying and solving important problems in various domains, ranging from food safety and environmental analysis, to healthcare and medicine. However, one of the most prominent drawbacks of these technologies, especially in the biomedical field, is to employ conventional samples, such as blood, urine, tissue extracts and other body fluids for analysis, which suffer from the drawbacks of invasiveness, discomfort, and high costs encountered in transportation and storage, thereby hindering these products to be applied for point-of-care testing that has garnered substantial attention in recent years. Therefore, through this review, we emphasize for the first time, the applications of switching over to noninvasive sampling techniques involving hair and nails that not only circumvent most of the aforementioned limitations, but also serve as interesting alternatives in understanding the human physiology involving minimal costs, equipment and human interference when combined with rapidly advancing technologies, such as microfluidics and organ-on-a-chip to achieve miniaturization on an unprecedented scale. The coalescence between these two fields has not only led to the fabrication of novel microdevices involving hair and nails, but also function as robust biosensors for the detection of biomarkers, chemicals, metabolites and nucleic acids through noninvasive sampling. Finally, we have also elucidated a plethora of futuristic innovations that could be incorporated in such devices, such as expanding their applications in nail and hair-based drug delivery, their potential in serving as next-generation wearable sensors and integrating these devices with machine-learning for enhanced automation and decentralization.

Advancing biological investigations using portable sensors for detection of sensitive samples

Portable biosensors are emerged as powerful diagnostic tools for analyzing intricately complex biological samples. These biosensors offer sensitive detection capabilities by utilizing biomolecules such as proteins, nucleic acids, microbes or microbial products, antibodies, and enzymes. Their speed, accuracy, stability, specificity, and low cost make them indispensable in forensic investigations and criminal cases. Notably, portable biosensors have been developed to rapidly detect toxins, poisons, body fluids, and explosives; they have proven invaluable in forensic examinations of suspected samples, generating efficient results that enable effective and fair trials. One of the key advantages of portable biosensors is their ability to provide sensitive and non-destructive detection of forensic samples without requiring extensive sample preparation, thereby reducing the possibility of false results. This comprehensive review provides an overview of the current advancements in portable biosensors for the detection of sensitive materials, highlighting their significance in advancing investigations and enhancing sensitive sample detection capabilities.

Advancing Healthcare: Synergizing Biosensors and Machine Learning for Early Cancer Diagnosis

Cancer is a fatal disease and a significant cause of millions of deaths. Traditional methods for cancer detection often have limitations in identifying the disease in its early stages, and they can be expensive and time-consuming. Since cancer typically lacks symptoms and is often only detected at advanced stages, it is crucial to use affordable technologies that can provide quick results at the point of care for early diagnosis. Biosensors that target specific biomarkers associated with different types of cancer offer an alternative diagnostic approach at the point of care. Recent advancements in manufacturing and design technologies have enabled the miniaturization and cost reduction of point-of-care devices, making them practical for diagnosing various cancer diseases. Furthermore, machine learning (ML) algorithms have been employed to analyze sensor data and extract valuable information through the use of statistical techniques. In this review paper, we provide details on how various machine learning algorithms contribute to the ongoing development of advanced data processing techniques for biosensors, which are continually emerging. We also provide information on the various technologies used in point-of-care cancer diagnostic biosensors, along with a comparison of the performance of different ML algorithms and sensing modalities in terms of classification accuracy.

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.

Application of biosensors in cancers, an overview

The deadliest disease in the world, cancer, kills many people every year. The early detection is the only hope for the survival of malignant cancer patients. As a result, in the preliminary stages of, the diagnosis of cancer biomarkers at the cellular level is critical for improving cancer patient survival rates. For decades, scientists have focused their efforts on the invention of biosensors. Biosensors, in addition to being employed in other practical scenarios, can essentially function as cost effective and highly efficient devices for this purpose. Traditional cancer screening procedures are expensive, time-consuming, and inconvenient for repeat screenings. Biomarker-based cancer diagnosis, on the other hand, is rising as one of the most potential tools for early detection, disease progression monitoring, and eventual cancer treatment. As Biosensor is an analytical device, it allows the selected analyte to bind to the biomolecules being studied (for example RNA, DNA, tissue, proteins, and cells). They can be divided based on the kind of biorecognition or transducer elements on the sensor. Most biosensor analyses necessitate the analyte being labeled with a specific marker. In this review article, the application of distinct variants of biosensors against cancer has been described.

Chirality in Light-Matter Interaction

The scientific effort to control the interaction between light and matter has grown exponentially in the last 2 decades. This growth has been aided by the development of scientific and technological tools enabling the manipulation of light at deeply sub-wavelength scales, unlocking a large variety of novel phenomena spanning traditionally distant research areas. Here, the role of chirality in light-matter interactions is reviewed by providing a broad overview of its properties, materials, and applications. A perspective on future developments is highlighted, including the growing role of machine learning in designing advanced chiroptical materials to enhance and control light-matter interactions across several scales.

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.

Recent advances in the detection of pathogenic microorganisms and toxins based on field-effect transistor biosensors

In food safety analysis, the detection and control of foodborne pathogens and their toxins are of great importance. Monitoring of virus transmission is equally important, especially in light of recent findings that coronaviruses have been detected in frozen foods and packages during the current global epidemic of coronavirus disease 2019. In recent years, field-effect transistor (FET) biosensors have attracted considerable scholarly attention for pathogenic microorganisms and toxins detection and sensing due to their rapid response time, high sensitivity, wide dynamic range, high specificity, label-free detection, portability, and cost-effectiveness. FET-based biosensors can be modified with specific recognition elements, thus providing real-time qualitative and semiquantitative analysis. Furthermore, with advances in nanotechnology and device design, various high-performance nanomaterials are gradually applied in the detection of FET-based biosensors. In this article, we review specific detection in different biological recognition elements are immobilized on FET biosensors for the detection of pathogenic microorganisms and toxins, and we also discuss nonspecific detection by FET biosensors. In addition, there are still unresolved challenges in the development and application of FET biosensors for achieving efficient, multiplexed, in situ detection of pathogenic microorganisms and toxins. Therefore, directions for future FET biosensor research and applications are discussed.

Graphene Oxide-Functionalized Thread-Based Electrofluidic Approach for DNA Hybridization

A novel, low-cost, and disposable thread-based electrofluidic analytical method employing isotachophoresis (ITP) was developed for demonstrating surface DNA hybridization. This approach was based on graphene oxide (GO) surface-functionalized zones on nylon threads as a binding platform to trap a fluorescently labeled isotachophoretically focused single-stranded DNA (ssDNA) band, resulting in quenching of the fluorescence, which signaled quantitative trapping. In the event of an isotachophoretically focused complementary DNA (cDNA) band passing over the GO-trapped ssDNA zone, surface hybridization of the ssDNA and cDNA to form double-stranded DNA (dsDNA) band occurred, which is released from the GO-coated zones, resulting in restoration of the fluorescent signal as it exits the GO band and migrates further along the thread. This controllable process demonstrates the potential of the GO-functionalized thread-based microfluidic analytical approach for DNA hybridization and its visualization, which could be adapted into point-of-care (POC) diagnostic devices for real-world applications.

Recent Trends in Biosensing and Diagnostic Methods for Novel Cancer Biomarkers

Cancer is one of the major public health issues in the world. It has become the second leading cause of death, with approximately 75% of cancer deaths transpiring in low- or middle-income countries. It causes a heavy global economic cost estimated at more than a trillion dollars per year. The most common cancers are breast, colon, rectum, prostate, and lung cancers. Many of these cancers can be treated effectively and cured if detected at the primary stage. Nowadays, around 50% of cancers are detected at late stages, leading to serious health complications and death. Early diagnosis of cancer diseases substantially increases the efficient treatment and high chances of survival. Biosensors are one of the potential screening methodologies useful in the early screening of cancer biomarkers. This review summarizes the recent findings about novel cancer biomarkers and their advantages over traditional biomarkers, and novel biosensing and diagnostic methods for them; thus, this review may be helpful in the early recognition and monitoring of treatment response of various human cancers.

Development of Electrochemical Immunosensors for HER-1 and HER-2 Analysis in Serum for Breast Cancer Patients

In this work, two human epidermal growth factor receptors, HER-1 and HER-2, were selected as biomarkers to enable the detection of breast cancer. Therefore, two biosensors were developed using gold sensor chips coupled with amperometric detection of the enzyme label horse radish peroxidase (HRP). The biosensors/immunosensors relied on indirect sandwich enzyme-linked immunosorbent assays with monoclonal antibodies (Ab) against HER-1 and HER-2 attached to the sensors to capture the biomarkers. Detection polyclonal antibodies followed by secondary anti-rabbit (for HER-1) and anti-goat (for HER-2) IgG antibody-HRP were then applied for signal generation. In buffer, the developed sensors showed limits of detections (LOD) of 1.06 ng mL^-1 and 0.95 ng mL^-1 and limits of quantification (LOQ) of 2.1 ng mL^-1 and 1.5 ng mL^-1 for HER-1 and HER-2, respectively. In 100% (undiluted) serum, LODs of 1.2 ng mL^-1 and 1.47 ng mL^-1 and LOQs of 1.5 ng mL^-1 and 2.1 ng mL^-1 were obtained for HER-1 and HER-2, respectively. Such limits of detections are within the serum clinical range for the two biomarkers. Furthermore, gold nanoparticles (AuNP) labelled with secondary anti-rabbit and anti-goat IgG antibody-HRP were then used to enhance the assay signal and increase the sensitivity. In buffers, LODs of 30 pg mL^-1 were seen for both sensors and LOQs of 98 pg mL^-1 and 35 pg mL^-1 were recorded for HER-1 and HER-2, respectively. For HER-2 the AuNPs biosensor was also tested in 100% serum obtaining a LOD of 50 pg mL^-1 and a LOQ of 80 pg mL^-1. The HER-2 AuNP electrochemical immunosensor showed high specificity with very low cross-reactivity to HER-1. These findings demonstrate that the two developed sensors can enable early detection as well as monitoring of disease progression with a beneficial impact on patient survival and clinical outcomes.

Molecular Diagnosis and Cancer Prognosis-A Concise Review

Cancer is a complicated disease. Globally, it is one of the major causes for morbidity and mortality. A critical challenge associated with it is the difficulty to accurately diagnose it at an early stage. The malignancy due to multistage and heterogeneity that result from genetic and epigenetic modifications poses critical challenge to diagnose and monitor the progress at an early stage. Current diagnostic techniques normally suggest invasive biopsy procedure that can cause further infections and bleeding. Therefore, noninvasive diagnostic methods with high accuracy, safety and earliest detection are the needs of the hour. Herein, we provide a detailed review on the advanced methodologies and protocols developed for the detection of cancer biomarkers based on proteins, nucleic acids and extracellular vesicles. Furthermore, existing challenges and the improvements essential for the rapid, sensitive and noninvasive detection have also been discussed.

Biomarkers and Corresponding Biosensors for Childhood Cancer Diagnostics

Although tremendous progress has been made in treating childhood cancer, it is still one of the leading causes of death in children worldwide. Because cancer symptoms overlap with those of other diseases, it is difficult to predict a tumor early enough, which causes cancers in children to be more aggressive and progress more rapidly than in adults. Therefore, early and accurate detection methods are urgently needed to effectively treat children with cancer therapy. Identification and detection of cancer biomarkers serve as non-invasive tools for early cancer screening, prevention, and treatment. Biosensors have emerged as a potential technology for rapid, sensitive, and cost-effective biomarker detection and monitoring. In this review, we provide an overview of important biomarkers for several common childhood cancers. Accordingly, we have enumerated the developed biosensors for early detection of pediatric cancer or related biomarkers. This review offers a restructured platform for ongoing research in pediatric cancer diagnostics that can contribute to the development of rapid biosensing techniques for early-stage diagnosis, monitoring, and treatment of children with cancer and reduce the mortality rate.

Biosensing chips for cancer diagnosis and treatment: a new wave towards clinical innovation

Recent technological advances in nanoscience and material designing have led to the development of point-of-care devices for biomolecule sensing and cancer diagnosis. In situ and portable sensing devices for bedside, diagnosis can effectively improve the patient’s clinical outcomes and reduce the mortality rate. Detection of exosomal RNAs by immuno-biochip with increased sensitivity and specificity to diagnose cancer has raised the understanding of the tumor microenvironment and many other technology-based biosensing devices hold great promise for clinical innovations to conquer the unbeatable fort of cancer metastasis. Electrochemical biosensors are the most sensitive category of biomolecule detection sensors with significantly low concentrations down to the atomic level. In this sense, this review addresses the recent advances in cancer detection and diagnosis by developing significant biological sensing devices that are believed to have better sensing potential than existing facilities.

Biosensors for detection of prostate cancer: a review

Diagnosis of prostate cancer (PC) has posed a challenge worldwide due to the sophisticated and costly diagnostics tools, which include DRE, TRUS, GSU, PET/CT scan, MRI, and biopsy. These diagnostic techniques are very helpful in the detection of PCs; however, all the techniques have their serious limitations. Biosensors are easier to fabricate and do not require any cutting-edge technology as required for other imaging techniques. In this regard, point-of-care (POC) biosensors are important due to their portability, convenience, low cost, and fast procedure. This review explains the various existing diagnostic tools for the detection of PCs and the limitation of these methods. It also focuses on the recent studies on biosensors technologies as an alternative to the conventional diagnostic techniques for the detection of PCs.

Emerging Biosensors for Oral Cancer Detection and Diagnosis—A Review Unravelling Their Role in Past and Present Advancements in the Field of Early Diagnosis

Oral cancer is a serious concern to people all over the world because of its high mortality rate and metastatic spread to other areas of the body. Despite recent advancements in biomedical research, OC detection at an early stage remains a challenge and is complex and inaccurate with conventional diagnostics procedures. It is critical to study innovative approaches that can enable a faster, easier, non-invasive, and more precise diagnosis of OC in order to increase the survival rate of patients. In this paper, we conducted a review on how biosensors might be an excellent tool for detecting OC. This review covers the strategies that use different biosensors to target various types of biomarkers and focuses on biosensors that function at the molecular level viz. DNA biosensors, RNA biosensors, and protein biosensors. In addition, we reviewed non-invasive electrochemical methods, optical methods, and nano biosensors to analyze the OC biomarkers present in body fluids such as saliva and serum. As a result, this review sheds light on the development of ground-breaking biosensors for the early detection and diagnosis of OC.

A Novel Microwave Resonant Sensor for Measuring Cancer Cell Line Aggressiveness

The measurement of biological tissues' dielectric properties plays a crucial role in determining the state of health, and recent studies have reported microwave biosensing to be an innovative method with great potential in this field. Research has been conducted from the tissue level to the cellular level but, to date, cellular adhesion has never been considered. In addition, conventional systems for diagnosing tumor aggressiveness, such as a biopsy, are rather expensive and invasive. Here, we propose a novel microwave approach for biosensing adherent cancer cells with different malignancy degrees. A circular patch resonator was designed adjusting its structure to a standard Petri dish and a network analyzer was employed. Then, the resonator was realized and used to test two groups of different cancer cell lines, based on various tumor types and aggressiveness: low- and high-aggressive osteosarcoma cell lines (SaOS-2 and 143B, respectively), and low- and high-aggressive breast cancer cell lines (MCF-7 and MDA-MB-231, respectively). The experimental results showed that the sensitivity of the sensor was high, in particular when measuring the resonant frequency. Finally, the sensor showed a good ability to distinguish low-metastatic and high-metastatic cells, paving the way to the development of more complex measurement systems for noninvasive tissue diagnosis.

Properties and Applications of Graphene and Its Derivatives in Biosensors for Cancer Detection: A Comprehensive Review

Cancer is one of the deadliest diseases worldwide, and there is a critical need for diagnostic platforms for applications in early cancer detection. The diagnosis of cancer can be made by identifying abnormal cell characteristics such as functional changes, a number of vital proteins in the body, abnormal genetic mutations and structural changes, and so on. Identifying biomarker candidates such as DNA, RNA, mRNA, aptamers, metabolomic biomolecules, enzymes, and proteins is one of the most important challenges. In order to eliminate such challenges, emerging biomarkers can be identified by designing a suitable biosensor. One of the most powerful technologies in development is biosensor technology based on nanostructures. Recently, graphene and its derivatives have been used for diverse diagnostic and therapeutic approaches. Graphene-based biosensors have exhibited significant performance with excellent sensitivity, selectivity, stability, and a wide detection range. In this review, the principle of technology, advances, and challenges in graphene-based biosensors such as field-effect transistors (FET), fluorescence sensors, SPR biosensors, and electrochemical biosensors to detect different cancer cells is systematically discussed. Additionally, we provide an outlook on the properties, applications, and challenges of graphene and its derivatives, such as Graphene Oxide (GO), Reduced Graphene Oxide (RGO), and Graphene Quantum Dots (GQDs), in early cancer detection by nanobiosensors.

Colorimetric Paper-Based Sensors against Cancer Biomarkers

Cancer is a major cause of mortality and morbidity worldwide. Detection and quantification of cancer biomarkers plays a critical role in cancer early diagnosis, screening, and treatment. Clinicians, particularly in developing countries, deal with high costs and limited resources for diagnostic systems. Using low-cost substrates to develop sensor devices could be very helpful. The interest in paper-based sensors with colorimetric detection increased exponentially in the last decade as they meet the criteria for point-of-care (PoC) devices. Cellulose and different nanomaterials have been used as substrate and colorimetric probes, respectively, for these types of devices in their different designs as spot tests, lateral-flow assays, dipsticks, and microfluidic paper-based devices (μPADs), offering low-cost and disposable devices. However, the main challenge with these devices is their low sensitivity and lack of efficiency in performing quantitative measurements. This review includes an overview of the use of paper for the development of sensing devices focusing on colorimetric detection and their application to cancer biomarkers. We highlight recent works reporting the use of paper in the development of colorimetric sensors for cancer biomarkers, such as proteins, nucleic acids, and others. Finally, we discuss the main advantages of these types of devices and highlight their major pitfalls.

Shining Light on Protein Kinase Biomarkers with Fluorescent Peptide Biosensors

Protein kinases (PKs) are established gameplayers in biological signalling pathways, and a large body of evidence points to their dysregulation in diseases, in particular cancer, where rewiring of PK networks occurs frequently. Fluorescent biosensors constitute attractive tools for probing biomolecules and monitoring dynamic processes in complex samples. A wide variety of genetically encoded and synthetic biosensors have been tailored to report on PK activities over the last decade, enabling interrogation of their function and insight into their behaviour in physiopathological settings. These optical tools can further be used to highlight enzymatic alterations associated with the disease, thereby providing precious functional information which cannot be obtained through conventional genetic, transcriptomic or proteomic approaches. This review focuses on fluorescent peptide biosensors, recent developments and strategies that make them attractive tools to profile PK activities for biomedical and diagnostic purposes, as well as insights into the challenges and opportunities brought by this unique toolbox of chemical probes.

Recent Advances in Quartz Crystal Microbalance Biosensors Based on the Molecular Imprinting Technique for Disease-Related Biomarkers

The molecular imprinting technique is a quickly developing field of interest regarding the synthesis of artificial recognition elements that enable the specific determination of target molecule/analyte from a matrix. Recently, these smart materials can be successfully applied to biomolecule detection in biomimetic biosensors. These biosensors contain a biorecognition element (a bioreceptor) and a transducer, like their biosensor analogs. Here, the basic difference is that molecular imprinting-based biosensors use a synthetic recognition element. Molecular imprinting polymers used as the artificial recognition elements in biosensor platforms are complementary in shape, size, specific binding sites, and functionality to their template analytes. Recent progress in biomolecular recognition has supplied extra diagnostic and treatment methods for various diseases. Cost-effective, more robust, and high-throughput assays are needed for monitoring biomarkers in clinical settings. Quartz crystal microbalance (QCM) biosensors are promising tools for the real-time and quick detection of biomolecules in the past two decades A quick, simple-to-use, and cheap biomarkers detection technology based on biosensors has been developed. This critical review presents current applications in molecular imprinting-based quartz crystal microbalance biosensors for the quantification of biomarkers for disease monitoring and diagnostic results.

A Review of Biosensors for Detecting Tumor Markers in Breast Cancer

Breast cancer has the highest cancer incidence rate in women. Early screening of breast cancer can effectively improve the treatment effect of patients. However, the main diagnostic techniques available for the detection of breast cancer require the corresponding equipment, professional practitioners, and expert analysis, and the detection cost is high. Tumor markers are a kind of active substance that can indicate the existence and growth of the tumor. The detection of tumor markers can effectively assist the diagnosis and treatment of breast cancer. The conventional detection methods of tumor markers have some shortcomings, such as insufficient sensitivity, expensive equipment, and complicated operations. Compared with these methods, biosensors have the advantages of high sensitivity, simple operation, low equipment cost, and can quantitatively detect all kinds of tumor markers. This review summarizes the biosensors (2013-2021) for the detection of breast cancer biomarkers. Firstly, the various reported tumor markers of breast cancer are introduced. Then, the development of biosensors designed for the sensitive, stable, and selective recognition of breast cancer biomarkers was systematically discussed, with special attention to the main clinical biomarkers, such as human epidermal growth factor receptor-2 (HER2) and estrogen receptor (ER). Finally, the opportunities and challenges of developing efficient biosensors in breast cancer diagnosis and treatment are discussed.

Optical bio-sensing of DNA methylation analysis: an overview of recent progress and future prospects

DNA methylation as one of the most important epigenetic modifications has a critical role in regulating gene expression and drug resistance in treating diseases such as cancer. Therefore, the detection of DNA methylation in the early stages of cancer plays an essential role in disease diagnosis. The majority of routine methods to detect DNA methylation are very tedious and costly. Therefore, designing easy and sensitive methods to detect DNA methylation directly and without the need for molecular methods is a hot topic issue in bioscience. Here we provide an overview on the optical biosensors (including fluorescence, FRET, SERs, colorimetric) that have been applied to detect the DNA methylation. In addition, various types of labeled and label-free reactions along with the application of molecular methods and optical biosensors have been surveyed. Also, the effect of nanomaterials on the sensitivity of detection methods is discussed. Furthermore, a comprehensive overview of the advantages and disadvantages of each method are provided. Finally, the use of microfluidic devices in the evaluation of DNA methylation and DNA damage analysis based on smartphone detection has been discussed.

Here, we provide an overview on the optical biosensors (including fluorescence, FRET, SERs, colorimetric) that have been applied to detect the DNA methylation.

Research progress of smart response composite hydrogels based on nanocellulose

In recent years, smart-responsive nanocellulose composite hydrogels have attracted extensive attention due to their unique porous substrate, hydrophilic properties, biocompatibility and stimulus responsiveness. At present, the research on smart response nanocellulose composite hydrogel mainly focuses on the selection of composite materials and the construction of internal chemical bonds. The common composite materials and connection methods used for preparation of smart response nanocellulose composite hydrogels are compared according to the different types of response sources such as temperature, pH and so on. The response mechanisms and the application prospects of different response types of nanocellulose composite hydrogels are summarized, and the transformation of internal ions, functional groups and chemical bonds, as well as the changes in mechanical properties such as modulus and strength are discussed. Finally, the shortcomings and application prospects of nanocellulose smart response composite hydrogels are summarized and prospected.

Microfluidic Biosensor-Based Devices for Rapid Diagnosis and Effective Anti-cancer Therapeutic Monitoring for Breast Cancer Metastasis

Breast cancer with unpredictable metastatic recurrence is the leading cause of cancer-related mortality. Early cancer detection and optimized therapy are the principal determining factors for increased survival rate. Worldwide, researchers and clinicians are in search of efficient strategies for the timely management of cancer progression. Efficient preclinical models provide information on cancer initiation, malignancy progression, relapse, and drug efficacy. The distinct histopathological features and clinical heterogeneity allows no single model to mimic breast tumor. However, engineering three-dimensional (3D) in vitro models incorporating cells and biophysical cues using a combination of organoid culture, 3D printing, and microfluidic technology could recapitulate the tumor microenvironment. These models serve to be preferable predictive models bridging the translational research gap in drug development. Microfluidic device is a cost-effective advanced in vitro model for cancer research, diagnosis, and drug assay under physiologically relevant conditions. Integrating a biosensor with microfluidics allows rapid real-time analytical validation to provide highly sensitive, specific, reproducible, and reliable outcomes. In this manner, the multi-system approach in identifying biomarkers associated with cancer facilitates early detection, therapeutic window optimization, and post-treatment evaluation.This chapter showcases the advancements related to in vitro breast cancer metastasis models focusing on microfluidic devices. The chapter aims to provide an overview of microfluidic biosensor-based devices for cancer detection and high-throughput chemotherapeutic drug screening.

On Demand Biosensors for Early Diagnosis of Cancer and Immune Checkpoints Blockade Therapy Monitoring from Liquid Biopsy

Recently, considerable interest has emerged in the development of biosensors to detect biomarkers and immune checkpoints to identify and measure cancer through liquid biopsies. The detection of cancer biomarkers from a small volume of blood is relatively fast compared to the gold standard of tissue biopsies. Traditional immuno-histochemistry (IHC) requires tissue samples obtained using invasive procedures and specific expertise as well as sophisticated instruments. Furthermore, the turnaround for IHC assays is usually several days. To overcome these challenges, on-demand biosensor-based assays were developed to provide more immediate prognostic information for clinicians. Novel rapid, highly precise, and sensitive approaches have been under investigation using physical and biochemical methods to sense biomarkers. Additionally, interest in understanding immune checkpoints has facilitated the rapid detection of cancer prognosis from liquid biopsies. Typically, these devices combine various classes of detectors with digital outputs for the measurement of soluble cancer or immune checkpoint (IC) markers from liquid biopsy samples. These sensor devices have two key advantages: (a) a small volume of blood drawn from the patient is sufficient for analysis, and (b) it could aid physicians in quickly selecting and deciding the appropriate therapy regime for the patients (e.g., immune checkpoint blockade (ICB) therapy). In this review, we will provide updates on potential cancer markers, various biosensors in cancer diagnosis, and the corresponding limits of detection, while focusing on biosensor development for IC marker detection.

Nucleic acid-based electrochemical biosensors for rapid clinical diagnosis: Advances, challenges, and opportunities

Clinical diagnostic tests should be quick, reliable, simple to perform, and affordable for diagnosis and treatment of diseases. In this regard, owing to their novel properties, biosensors have attracted the attention of scientists as well as end-users. They are efficient, stable, and relatively cheap. Biosensors have broad applications in medical diagnosis, including point-of-care (POC) monitoring, forensics, and biomedical research. The electrochemical nucleic acid (NA) biosensor, the latest invention in this field, combines the sensitivity of electroanalytical methods with the inherent bioselectivity of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). The NA biosensor exploits the affinity of single-stranded DNA/RNA for its complementary strand and is used to detect complementary sequences of NA based on hybridization. After the NA component in the sensor detects the analyte, a catalytic reaction or binding event that generates an electrical signal in the transducer ensues. Since 2000, much progress has been made in this field, but there are still numerous challenges. This critical review describes the advances, challenges, and prospects of NA-based electrochemical biosensors for clinical diagnosis. It includes the basic principles, classification, sensing enhancement strategies, and applications of biosensors as well as their advantages, limitations, and future prospects, and thus it should be useful to academics as well as industry in the improvement and application of EC NA biosensors.

A label-free graphene-based impedimetric biosensor for real-time tracing of the cytokine storm in blood serum; suitable for screening COVID-19 patients

Concurrent with the pandemic announcement of SARS-CoV-2 infection by the WHO, a variety of reports were published confirming the cytokine storm as the most mortal effect of the virus on the infected patients. Hence, cytokine storm as an evidenced consequence in most of the COVID-19 patients could offer a promising opportunity to use blood as a disease progression marker. Here, we have developed a rapid electrochemical impedance spectroscopy (EIS) sensor for quantifying the overall immune activity of the patients. Since during the cytokine storm many types of cytokines are elevated in the blood, there is no need for specific detection of a single type of cytokine and the collective behavior is just measured without any electrode functionalization. The sensor includes a monolayer graphene on a copper substrate as the working electrode (WE) which is able to distinguish between the early and severe stage of the infected patients. The charge transfer resistance (R CT) in the moderate and severe cases varies about 65% and 138% compared to the normal groups, respectively and a specificity of 77% and sensitivity of 100% based on ELISA results were achieved. The outcomes demonstrate a significant correlation between the total mass of the three main hypercytokinemia associated cytokines including IL-6, TNF-α and IFN-γ in patients and the R CT values. As an extra application, the biosensor's capability for diagnosis of COVID-19 patients was tested and a sensitivity of 92% and specificity of 50% were obtained compared to the RT-PCR results.

Malignancies and Biosensors: A Focus on Oral Cancer Detection through Salivary Biomarkers

Oral cancer is among the deadliest types of malignancy due to the late stage at which it is usually diagnosed, leaving the patient with an average five-year survival rate of less than 50%. The booming field of biosensing and point of care diagnostics can, in this regard, play a major role in the early detection of oral cancer. Saliva is gaining interest as an alternative biofluid for non-invasive diagnostics, and many salivary biomarkers of oral cancer have been proposed. While these findings are promising for the application of salivaomics tools in routine practice, studies on larger cohorts are still needed for clinical validation. This review aims to summarize the most recent development in the field of biosensing related to the detection of salivary biomarkers commonly associated with oral cancer. An introduction to oral cancer diagnosis, prognosis and treatment is given to define the clinical problem clearly, then saliva as an alternative biofluid is presented, along with its advantages, disadvantages, and collection procedures. Finally, a brief paragraph on the most promising salivary biomarkers introduces the sensing technologies commonly exploited to detect oral cancer markers in saliva. Hence this review provides a comprehensive overview of both the clinical and technological advantages and challenges associated with oral cancer detection through salivary biomarkers.

An electrochemical aptasensor for detection of prostate-specific antigen using reduced graphene gold nanocomposite and Cu/carbon quantum dots

We report a label-free electrochemical aptamer-based biosensor for the detection of human prostate-specific antigen (PSA). The thiolate DNA aptamer against PSA was conjugated to the reduced graphene oxide/Au (RGO-Au) nanocomposite through the self-assembly of Au-S groups. Owing to the large volume to surface ratio, the RGO-Au nanocomposite provides a large surface for aptamer loading. The RGO-Au/aptamer was combined with a Nafion polymer and immobilized on a glassy carbon electrode. The interaction of aptamer with PSA was studied by cyclic voltammetry, square wave voltammetry, and electrochemical impedance spectroscopy. The detection of limit for prepared electrode was obtained about 50 pg/mL at the potential of 0.4 V in potassium hexacyanoferrate [K₄ Fe(CN)₆ ] medium. To decrease the limit of detection (LOD) and applied potential of the prepared nanoprobe Cu/carbon quantum dots (CuCQD) is introduced as a new redox. The results show that this new electrochemical medium provides better conditions for the detection of PSA. LOD of a nanoprobe in CuCQD media was obtained as 40 pg/mL at the potential of -0.2 V. Under optimal conditions, the aptasensor exhibits a linear response to PSA with a LOD as small as 3 pg/mL. The present aptasensor is highly selective and sensitive and shows satisfactory stability and repeatability.

Immunosensor for Assessing the Welfare of Trainee Guide Dogs

Cortisol is a well established biomarker hormone that regulates many processes in the body and is widely referred to as the stress hormone. Cortisol can be used as a stress marker to allow for detection of stress levels in dogs during the training process. This test will indicate if they will handle the stress under the training or if they might be more suitable as an assistant or companion dog. An immunosensor for detection of cortisol was developed using electrochemical impedance spectroscopy (EIS). The sensor was characterized using chemical and topographical techniques. The sensor was calibrated and its sensitivity determined using a cortisol concentration range of 0.0005 to 50 μg/mL. The theoretical limit of detection was found to be 3.57 fg/mL. When the immunosensor was tested on canine saliva samples, cortisol was detected and measured within the relevant physiological ranges in dogs.

A Comprehensive Study on Aptasensors For Cancer Diagnosis

Cancer is the most devastating disease in the present scenario, killing millions of people every year. Early detection, accurate diagnosis, and timely treatment are considered to be the most effective ways to control this disease. Rapid and efficient detection of cancer at their earliest stage is one of the most significant challenges in cancer detection and cure. Numerous diagnostic modules have been developed to detect cancer cells early. As nucleic acid equivalent to antibodies, aptamers emerge as a new class of molecular probes that can identify cancer-related biomarkers or circulating rare cancer/ tumor cells with very high specificity and sensitivity. The amalgamation of aptamers with the biosensing platforms gave birth to "Aptasensors." The advent of highly sensitive aptasensors has opened up many new promising point-of-care diagnostics for cancer. This comprehensive review focuses on the newly developed aptasensors for cancer diagnostics.

A New Nanomaterial Based Biosensor for MUC1 Biomarker Detection in Early Diagnosis, Tumor Progression and Treatment of Cancer

Early detection of cancer disease is vital to the successful treatment, follow-up and survival of patients, therefore sensitive and specific methods are still required. Mucin 1 (MUC1) is a clinically approved biomarker for determining the cancer that is a type I transmembrane protein with a dense glycosylated extracellular domain extending from the cell surface to 200–500 nm. In this study, nanopolymers were designed with a lectin affinity-based recognition system for MUC1 detection as a bioactive layer on electrochemical biosensor electrode surfaces. They were synthesized using a mini emulsion polymerization method and derivatized with triethoxy-3-(2-imidazolin-1-yl) propylsilane (IMEO) and functionalized with Concanavalin a Type IV (Con A) lectin. Advanced characterization studies of nanopolymers were performed. The operating conditions of the sensor system have been optimized. Biosensor validation studies were performed. Real sample blood serum was analyzed and this new method compared with a commercially available medical diagnostic kit (Enzyme-Linked ImmunoSorbent Assay-ELISA). The new generation nanopolymeric material has been shown to be an affordable, sensitive, reliable and rapid device with 0.1–100 U/mL linear range and 20 min response time.

Non-covalently embedded oxytocin in alkanethiol monolayer as Zn2+ selective biosensor

Peptides are commonly used as biosensors for analytes such as metal ions as they have natural binding preferences. In our previous peptide-based impedimetric metal ion biosensors, a monolayer of the peptide was anchored covalently to the electrode. Binding of metal ions resulted in a conformational change of the oxytocin peptide in the monolayer, which was measured using electrochemical impedance spectroscopy. Here, we demonstrate that sensing can be achieved also when the oxytocin is non-covalently integrated into an alkanethiol host monolayer. We show that ion-binding cause morphological changes to the dense host layer, which translates into enhanced impedimetric signals compared to direct covalent assembly strategies. This biosensor proved selective and sensitive for Zn2+ ions in the range of nano- to micro-molar concentrations. This strategy offers an approach to utilize peptide flexibility in monitoring their response to the environment while embedded in a hydrophobic monolayer.

Electrochemical prostate-specific antigen biosensors based on electroconductive nanomaterials and polymers

Prostate cancer (PCa), the second most malignant neoplasm in men, is also the fifth leading cause of cancer-related deaths in men globally. Unfortunately, this malignancy remains largely asymptomatic until late-stage emergence when treatment is limited due to the lack of effective metastatic PCa therapeutics. Due to these limitations, early PCa detection through prostate-specific antigen (PSA) screening has become increasingly important, resulting in a more than 50% decrease in mortality. Conventional assays for PSA detection, such as enzyme-linked immunosorbent assay (ELISA), are labor intensive, relatively expensive, operator-dependent and do not provide adequate sensitivity. Electrochemical biosensors overcome these limitations because they are rapid, cost-effective, simple to use and ultrasensitive. This article reviews electrochemical PSA biosensors using electroconductive nanomaterials such as carbon-, metal-, metal oxide- and peptide-based nanostructures, as well as polymers to significantly improve conductivity and enhance sensitivity. Challenges associated with the development of these devices are discussed thus providing additional insight into their analytic strength as well as their potential use in early PCa detection.

Development of rapid colorimetric assay for the detection of Influenza A and B viruses

The flu viruses are respiratory pathogens which, according to the World Health Organization (WHO), infect 5-10% of the world population resulting in 3-5 million cases of severe illness and 290,000 to 650,000 annual deaths. Early diagnosis and therapeutic intervention can ameliorate symptoms of infection and reduce mortality. The conventional diagnosis of viral infections, including flu viruses, has evolved over the years with diverse approaches, however, there are inherent short comings associated with these testing. There is an urgent need for rapid and low-cost diagnostic assays, due to the enormous annual burden of influenza diseases and its associated mortality. In this study, novel, low cost and easy to use colorimetric flu virus biosensor assay was developed. The sandwich assay format was utilized using antibodies immobilized onto cotton swabs, for the rapid detection of flu A and B viruses. These swabs serve as sample collection, analytes pre-concentration as well as sensing tool. The proof of concept was established for this assay in buffer and mucus samples. The limit of detection (LOD) of the colorimetric assay was 0.04 ng mL-1 for Flu A and Flu B respectively and with linear dynamic range between 0.04 ng ml-1 to 40 ng ml for both viruses in mucous samples. The assay can be performed at the patient's bed side by minimally skilled hospital personnel without the need for instrumentation. Cross-reactivity assays testing was done using Flu viruses specific activated swabs reacted with other common respiratory viral pathogens' antigen, in order to assess the specificity of the swabs.

Determination of carcinoembryonic antigen as a tumor marker using a novel graphene-based label-free electrochemical immunosensor

In this work, a simple label-free electrochemical immunosensor for the detection of carcinoembryonic antigen (CEA) was developed. At first, the GC electrode was coated with partially reduced graphene oxide (rGO) to form a platform to bind the antibody. After activating the carboxyl groups of rGO through the EDC/NHS linker, the electrode surface was covered with the antibody. Then, the electrochemical behavior of the antibody-modified electrode and the parameters of the interactions of antibody-antigen immune complexes were investigated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). This immune-complex layer was found to attenuate the electrochemical current which can be used as a good signal to determine the antigen concentration. The proposed immunosensor exhibited a good amperometric response to CEA within a concentration range of 0.1-5 ng mL^-1 with a detection limit of 0.05 ng ml^-1. Furthermore, the developed method was evaluated for the detection of CEA in the real sample (human blood serum), and the results were comparable with the reference values obtained by the standard enzyme-linked immunosorbent assay (ELISA). Our findings suggest the present immunosensor as a good candidate for application in clinical screening.