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

Electrochemical sensors: Types, applications, and the novel impacts of vibration and fluid flow for microfluidic integration

Electrochemical sensors are part of a diverse and evolving world of chemical sensors that are impacted by high demand and ongoing technological advancements. Electrochemical sensors offer benefits like cost-efficiency, short response time, ease of use, good limit of detection (LOD) and sensitivity, and ease of miniaturization while providing consistent analytical results. These sensors are employed in various fields-such as healthcare and diagnostics, environmental monitoring, and the food industry-to detect bacteria, viruses, heavy metals, pesticides, and more. In this review, we provide a comprehensive overview of electrochemical sensing techniques, with a focus on enhancing sensor performance through the integration of vibration and hydrodynamic flow in microfluidic systems. We present a structured comparison of these methods, utilizing tables to highlight the approaches most effective for performance enhancement. Additionally, we classify various electrochemical sensing applications, offering insights into the practical utilization of these two techniques for lowering the LOD. Finally, we present a comparative analysis of relevant studies, highlighting how hydrodynamic flow and vibration impact the sensing mechanism. We also explore the potential of these techniques to facilitate the development of automated, high-throughput microfluidic platforms, thereby optimizing their functionality and efficiency.

Tailoring Design of Microneedles for Drug Delivery and Biosensing

Microneedles (MNs) are emerging as versatile tools for both therapeutic drug delivery and diagnostic monitoring. Unlike hypodermic needles, MNs achieve these applications with minimal or no pain and customizable designs, making them suitable for personalized medicine. Understanding the key design parameters and the challenges during contact with biofluids is crucial to optimizing their use across applications. This review summarizes the current fabrication techniques and design considerations tailored to meet the distinct requirements for drug delivery and biosensing applications. We further underscore the current state of theranostic MNs that integrate drug delivery and biosensing and propose future directions for advancing MNs toward clinical use.

Nanobodies' duo facilitates ultrasensitive serum HER-2/neu immunoassays via enhanced avidity interactions

BACKGROUND

Existing liquid biopsy assays for protein biomarkers of cancer are mostly based on antibodies (Ab) contributing unfavorably to their high cost. Easy to express and modify in vitro, nanobodies may be a cost-effective alternative to Ab.

RESULTS

We show that serum HER-2/neu, a biomarker and target of aggressive HER-2/neu(+) cancers, can be accurately detected in a 1.2 h electrochemical cellulase-linked sandwich nanobody/aptamer assay on magnetic beads. Using a single nanobody receptor, 2Rs15d or 2Rb17c, reduces immunoassay's sensitivity by 35%-26 %. A combination of two nanobodies as a duo-receptor recovers the sensitivity of the enzyme-linked nanobody/aptamer-sorbent assay (ELNASA) to 11.9 ± 2.8 μC fM-1, due to the avidity effects making the nanobodies-duo binding properties comparable to those of Ab. Down to 0.1 fM HER-2/neu was detected by ELNASA in serum samples, with no interference from other blood-circulating proteins. In a 30 healthy-volunteers trial, ELNASA more accurately than optical ELISA assayed serum HER-2/neu.

SIGNIFICANCE

ELNASA performance rivals that of ELISA, yet estimated to be at least 200 times cheaper, due to the lower cost of nanobodies production, and may be better suited for routine clinical analysis of HER-2/neu, particularly, in low- and middle-income settings with limited resources. The ELNASA approach is generic and may be adapted for specific and ultrasensitive analysis of other blood-circulating proteins.

A versatile gold leaf immunosensor with a novel surface functionalization strategy based on protein L and trastuzumab for HER2 detection

Although various sensors specifically developed for target analytes are available, affordable biosensing solutions with broad applicability are limited. In this study, a cost-effective biosensor for detecting human epidermal growth factor receptor 2 (HER2) was developed using custom-made gold leaf electrodes (GLEs). A novel strategy for antibody immobilization on a gold surface, for the first time mediated by protein L and HER2-specific antibody trastuzumab, was examined using commercial screen-printed gold electrodes and GLEs. A self-assembled monolayer of 11-mercaptoundecanoic acid (MUA) was formed on the gold surface, which was used to covalently immobilize protein L. Further binding of trastuzumab to the protein L was employed and HER2 detection was achieved through electrochemical impedance spectroscopy (EIS). The HER2 detection was examined in phosphate-buffered saline (PBS) and supplemented cell culture medium. The modified GLEs showed good specificity and high sensitivity of HER2 detection without any enrichment steps, achieving a limit of detection (LOD) of 1 ng mL- 1 in PBS and 2.7 ng mL- 1 in cell culture medium, making the proposed immunosensor a cost-effective and sensitive solution for detection in complex biological matrices.

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.

Gold Nanoparticles: Multifunctional Properties, Synthesis, and Future Prospects

Gold nanoparticles (NPs) are among the most commonly employed metal NPs in biological applications, with distinctive physicochemical features. Their extraordinary optical properties, stemming from strong localized surface plasmon resonance (LSPR), contribute to the development of novel approaches in the areas of bioimaging, biosensing, and cancer research, especially for photothermal and photodynamic therapy. The ease of functionalization with various ligands provides a novel approach to the precise delivery of these molecules to targeted areas. Gold NPs' ability to transfer heat and electricity positions them as valuable materials for advancing thermal management and electronic systems. Moreover, their inherent characteristics, such as inertness, give rise to the synthesis of novel antibacterial and antioxidant agents as they provide a biocompatible and low-toxicity approach. Chemical and physical synthesis methods are utilized to produce gold NPs. The pursuit of more ecologically sustainable and economically viable large-scale technologies, such as environmentally benign biological processes referred to as green/biological synthesis, has garnered increasing interest among global researchers. Green synthesis methods are more favorable than other synthesis techniques as they minimize the necessity for hazardous chemicals in the reduction process due to their simplicity, cost-effectiveness, energy efficiency, and biocompatibility. This article discusses the importance of gold NPs, their optical, conductivity, antibacterial, antioxidant, and anticancer properties, synthesis methods, contemporary uses, and biosafety, emphasizing the need to understand toxicology principles and green commercialization strategies.

Integrating machine learning and biosensors in microfluidic devices: A review

Microfluidic devices are increasingly widespread in the literature, being applied to numerous exciting applications, from chemical research to Point-of-Care devices, passing through drug development and clinical scenarios. Setting up these microenvironments, however, introduces the necessity of locally controlling the variables involved in the phenomena under investigation. For this reason, the literature has deeply explored the possibility of introducing sensing elements to investigate the physical quantities and the biochemical concentration inside microfluidic devices. Biosensors, particularly, are well known for their high accuracy, selectivity, and responsiveness. However, their signals could be challenging to interpret and must be carefully analysed to carry out the correct information. In addition, proper data analysis has been demonstrated even to increase biosensors' mentioned qualities. To this regard, machine learning algorithms are undoubtedly among the most suitable approaches to undertake this job, automatically learning from data and highlighting biosensor signals' characteristics at best. Interestingly, it was also demonstrated to benefit microfluidic devices themselves, in a new paradigm that the literature is starting to name "intelligent microfluidics", ideally closing this benefic interaction among these disciplines. This review aims to demonstrate the advantages of the triad paradigm microfluidics-biosensors-machine learning, which is still little used but has a great perspective. After briefly describing the single entities, the different sections will demonstrate the benefits of the dual interactions, highlighting the applications where the reviewed triad paradigm was employed.

The portable stochastic sensor as a screening tool for simultaneous determination of HER-1 and CA 125 - a key factor in the rapid recognition of gastric cancer

The significance of HER-1 and CA 125 lies in their ability to guide cancer diagnosis, treatment, and monitoring, improving personalized care and enhancing prognostic accuracy. The utilization of HER-1 and CA 125 as screening biomarkers for the anticipation of early-stage cancer and monitoring cancer progression is expanding due to the invasive and costly nature of present techniques. In this study, a novel stochastic sensor was developed for the simultaneous determination of HER-1 and CA 125 in whole blood, saliva, and gastric tumor tissue samples using a fast, easy, inexpensive, and portable method. The stochastic sensor was prepared by electropolymerization of cysteine on the surface of the Au-TiO2@rGO/SPCE sensor. The Au-TiO2@rGO nanocomposite was synthesized using a simple chemical reduction process. The proposed sensor showed wide linear concentration ranges and very low limits of quantification (LOQ). The concentration ranges were from 3.9 × 10-14 to 3.9 × 10-8 µg mL-1, with a LOQ of 3.9 × 10-14 µg mL-1 for HER-1. For CA 125, the concentration ranges were from 8.3 × 10-14 to 8.3 × 10-10 U mL-1, with a LOQ of 8.3 × 10-14 U mL-1. Both biomarkers exhibit precise discrimination in different biological samples, with recoveries above 96.78% and RSD values below 0.04%. With a confidence level of 99%, the Student t-test revealed that there is no statistically significant difference between the outcomes obtained by using the poly-Cys/Au-TiO2@rGO/SPCE sensor for screening examinations of biological samples. This was determined because the results were not significantly different from one another.

Screen-Printed Electrodes as Low-Cost Sensors for Breast Cancer Biomarker Detection

This review explores the emerging role of screen-printed electrodes (SPEs) in the detection of breast cancer biomarkers. We discuss the fundamental principles and fabrication techniques of SPEs, highlighting their adaptability and cost-effectiveness. The review examines various modification strategies, including nanomaterial incorporation, polymer coatings, and biomolecule immobilization, which enhance sensor performance. We analyze the application of SPEs in detecting protein, genetic, and metabolite biomarkers associated with breast cancer, presenting recent advancements and innovative approaches. The integration of SPEs with microfluidic systems and their potential in wearable devices for continuous monitoring are explored. While emphasizing the promising aspects of SPE-based biosensors, we also address current challenges in sensitivity, specificity, and real-world applicability. The review concludes by discussing future perspectives, including the potential for early screening and therapy monitoring, and the steps required for clinical implementation. This comprehensive overview aims to stimulate further research and development in SPE-based biosensors for improved breast cancer management.

A new insight into the early detection of HER2 protein in breast cancer patients with a focus on electrochemical biosensors approaches: A review

Breast cancer is one of the leading causes of death in women and is a prevalent kind of cancerous growth, representing a substantial risk to women's health. Early detection of breast cancer is essential for effective treatment and improved survival rates. Biomarkers, active substances that signal the existence and advancement of a tumor, play a significant role in the early detection of breast cancer. Hence, accurate identification of biomarkers for tumors is crucial for diagnosing and treating breast cancer. However, the primary diagnostic methods used for the detection of breast cancer require specific equipment, skilled professionals, and specialized analysis, leading to elevated detection expenses. Regarding this obstacle, recent studies emphasize electrochemical biosensors as more advanced and sensitive detection tools compared to traditional methods. Electrochemical biosensors are employed to identify biomarkers that act as unique indicators for the onset, recurrence, and monitoring of therapeutic interventions for breast cancer. This study aims to provide a summary of the electrochemical biosensors that have been employed for the detection of breast cancer at an early stage over the past decade. Initially, the text provides concise information about breast cancer and tumor biomarkers. Subsequently, an in-depth analysis is conducted to systematically review the progress of electrochemical biosensors developed for the stable, specific, and sensitive identification of biomarkers associated with breast cancer. Particular emphasis was given to crucial clinical biomarkers, specifically the human epidermal growth factor receptor-2 (HER2). The analysis then explores the limitations and challenges inherent in the design of effective biosensors for diagnosing and treating breast cancer. Ultimately, we provided an overview of future research directions and concluded by outlining the advantages of electrochemical biosensor approaches.

Label-free and label-based electrochemical detection of disease biomarker proteins

Introduction

Biosensors, analytical devices integrating biological sensing elements with physicochemical transducers, have gained prominence as rapid and convenient tools for monitoring human health status using biochemical analytes. Due to its cost-effectiveness, simplicity, portability, and user-friendliness, electrochemical detection has emerged as a widely adopted method in biosensor applications. Crucially, biosensors enable early disease diagnosis by detecting protein biomarkers associated with various conditions. These biomarkers offer an objective indication of medical conditions that can be accurately observed from outside the patient.

Method

This review comprehensively documents both label-free and labelled detection methods in electrochemical biosensor techniques. Label-free detection mechanisms elicit response signals upon analyte molecule binding to the sensor surface, while labelled detection employs molecular labels such as enzymes, nanoparticles, and fluorescent tags.

Conclusion

The selection between label-free and labelled detection methods depends on various factors, including the biomolecular compound used, analyte type and biological binding site, biosensor design, sample volume, operational costs, analysis time, and desired detection limit. Focusing on the past six years, this review highlights the application of label-free and labelled electrochemical biosensors for detecting protein biomarkers of diseases.

Fabrication of label-free immunoprobe for monkeypox A29 detection using one-step electrodeposited molybdenum oxide-graphene quantum rods

Monkeypox is a zoonotic viral infection caused by the monkeypox virus (MPXV), which belongs to the Poxviridae family of the Orthopoxvirus (OPXV) genus. Monkeypox is transmitted from animals to humans and humans to humans; therefore, the accurate and early detection of MPXV is crucial for reducing mortality. A novel graphene-based material, graphene quantum rods (GQRs) was synthesized and confirmed using high-resolution transmission electron microscopy (HR-TEM) and atomic force microscopy (AFM). In this study, molybdenum oxide was electrodeposited and one-pot electrodeposition of MoO3-GQRs composite on carbon fiber paper (CFP) enabled by an antibody (Ab A29)/MoO3-GQRs immunoprobe was developed for the early diagnosis of MPXV protein (A29P). Several studies were conducted to analyze the MoO3-GQRs composite, and the prepared Ab A29/MoO3-GQRs immunoprobe selectively bound to the A29P antigen that was measured using differential pulse voltammetry (DPV) analysis and impedance spectroscopy. The antigen-antibody interaction was analyzed using X-ray photoelectron spectroscopy. DPV analysis showed a wide linear range of detection from 0.5 nM to 1000 nM, a detection limit of 0.52 nM, and a sensitivity of 4.51 µA in PBS. The prepared immunoprobe was used to analyze A29P in serum samples without reducing electrode sensitivity. This system is promising for the clinical analysis of A29P antigen and offers several advantages, including cost-effectiveness, ease of use, accuracy, and high sensitivity.

Convenient determination of serum HER-2 status in breast cancer patients using Raman spectroscopy

Given the significant therapeutic efficacy of anti-HER-2 treatment, the HER-2 status is a crucial piece of information that must be obtained in breast cancer patients. Currently, as per guidelines, HER-2 status is typically acquired from breast tissue of patients. However, there is growing interest in obtaining HER-2 status from serum and other samples due to the convenience and potential for dynamic monitoring. In this study, we have developed a serum Raman spectroscopy technique that allows for the rapid acquisition of HER-2 status in a convenient manner. The established HER-2 negative and positive classification model achieved an area under the curve of 0.8334. To further validate the reliability of our method, we replicated the process using immunohistochemistry and in situ hybridization. The results demonstrate that serum Raman spectroscopy, coupled with artificial intelligence algorithms, is an effective technical approach for obtaining HER-2 status.

Electrochemical bio- and chemosensors for cancer biomarkers: Natural (with antibodies) versus biomimicking artificial (with aptamers and molecularly imprinted polymers) recognition

Electrochemical (EC) bio- and chemosensors are highly promising for on-chip and point-of-care testing (POST) devices. They can make a breakthrough in early cancer diagnosis. Most current EC sensors for cancer biomarkers' detection and determination use natural antibodies as recognition units. However, those quickly lose their biorecognition ability upon exposure to harsh environments, comprising extreme pH, humidity, temperature, etc. So-called "plastic antibodies," including aptamers and molecularly imprinted polymers (MIPs), are hypothesized to be a smart alternative to antibodies. They have attracted the interest of the sensor research community, offering a low cost-to-performance ratio with high stability, an essential advantage toward their commercialization. Herein, we critically review recent technological advances in devising and fabricating EC bio- and chemosensors for cancer biomarkers, classifying them according to the type of recognition unit used into three categories, i.e., antibody-, aptamer-, and MIP-based EC sensors for cancer biomarkers. Each sensor fabrication strategy has been discussed, from the devising concept to cancer sensing applications, including using different innovative nanomaterials and signal transduction strategies. Moreover, employing each recognition unit in the EC sensing of cancer biomarkers has been critically compared in detail to enlighten each recognition unit's advantages, effectiveness, and limitations.

FeNC nanozyme-based electrochemical immunoassay for sensitive detection of human epidermal growth factor receptor 2

The proof-of-concept of sensitive electrochemical immunoassay for the quantitative monitoring of human epidermal growth factor receptor 2 (HER2) is reported. The assay is carried out on iron nitrogen-doped carbon (FeNC) nanozyme-modified screen-printed carbon electrode using chronoamperometry. Introduction of target HER2 can induce the sandwiched immunoreaction between anti-HER2 monoclonal antibody-coated microplate and biotinylated anti-HER2 polyclonal antibody. Thereafter, streptavidin-glucose oxidase (GOx) conjugate is bonded to the detection antibody. Upon addition of glucose, 3,3',5,5'-tetramethylbenzidine (TMB) is oxidized through the produced H2O2 with the assistance of GOx and FeNC nanozyme. The oxidized TMB is determined via chronoamperometry. Experimental results revealed that electrochemical immunosensing system exhibited good amperometric response, and allowed the detection of target HER2 as low as 4.5 pg/mL. High specificity and long-term stability are acquired with FeNC nanozyme-based sensing strategy. Importantly, our system provides a new opportunity for protein diagnostics.

Progress in Electrochemical Immunosensors with Alkaline Phosphatase as the Signal Label

Electrochemical immunosensors have shown great potential in clinical diagnosis, food safety, environmental protection, and other fields. The feasible and innovative combination of enzyme catalysis and other signal-amplified elements has yielded exciting progress in the development of electrochemical immunosensors. Alkaline phosphatase (ALP) is one of the most popularly used enzyme reporters in bioassays. It has been widely utilized to design electrochemical immunosensors owing to its significant advantages (e.g., high catalytic activity, high turnover number, and excellent substrate specificity). In this work, we summarized the achievements of electrochemical immunosensors with ALP as the signal reporter. We mainly focused on detection principles and signal amplification strategies and briefly discussed the challenges regarding how to further improve the performance of ALP-based immunoassays.

Comparative study of electrochemical-based sensors and immunosensors in terms of advantageous features for detection of cancer biomarkers

Cancer, becoming increasingly common globally, has a high mortality rate. Despite the much research on diagnosis and treatment methods, the benefits of technological developments, and newly developed sensor devices, cancer is still one of the leading causes of death worldwide. Early detection using powerful and noninvasive tools could be a future focus for prognosis and treatment follow-up. Therefore, electrochemical biosensors can be a strong choice for the detection of cancer biomarkers (such as alpha-fetoprotein, cytochrome c, prostate-specific antigen, myoglobin, carcinoembryonic antigen, alpha-fetoprotein, a cancer antigen, epidermal growth factor receptor, vascular endothelial growth factor, circulating tumor cell, and breast cancer antigen 1/2) due to their advantages such as high sensitivity, excellent selectivity, low cost, short analysis time, and simplicity. Furthermore, electrochemical biosensors are better suited for point-of-care applications due to their mass production and miniaturization ease. This review provides an overview of different electrochemical measurement techniques, bioreceptor surfaces, signal production and amplification, and the integration of electrochemical-modified sensors. Cancer biomarkers based on electrochemical biosensors were given in detail. In addition, studies with MIP-based sensors and immunosensors have been extensively discussed. Integrating electrochemical biosensors with cancer biomarkers was also emphasized as a new research trend. Finally, we provide an overview of current advances in measuring and analyzing cancer biomarkers using electrochemical biosensors and detail current challenges and future perspectives.

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.

Clinically Deployable Bioelectronic Sensing Platform for Ultrasensitive Detection of Transferrin in Serum Sample

Varying levels of transferrin (Tf) have been associated with different disease conditions and are known to play a crucial role in various malignancies. Regular monitoring of the variations in Tf levels can be useful for managing related diseases, especially for the prognosis of certain cancers. We fabricated an immunosensor based on graphene oxide (GO) nanosheets to indirectly detect Tf levels in cancer patients. The GO nanosheets were deposited onto an indium tin oxide (ITO)-coated glass substrate and annealed at 120 °C to obtain reduced GO (rGO) films, followed by the immobilization of an antibody, anti-Tf. The materials and sensor probe used were systematically characterized by UV-Visible spectroscopy (UV-Vis), X-ray diffraction (XRD), atomic force microscopy (AFM), and Fourier transform infrared spectroscopy (FTIR). Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV) were also used for the stepwise sensor probe characterizations and Tf detection in serum samples, respectively. The anti-Tf/rGO/ITO immunosensor DPV output demonstrated an excellent Tf detection capability in the linear range of 0.1 mg mL^-1 to 12 mg mL^-1 compared to the enzyme-linked immunosorbent assay (ELISA) detection range, with a limit of detection (LOD) of 0.010 ± 0.007 mg mL^-1. Furthermore, the results of the fabricated immunosensor were compared with those of the ELISA and autobioanalyzer techniques, showing an outstanding match with < 5% error and demonstrating the immunosensor's clinical potential.