Electrochemical and photoelectrochemical nano-immunesensing using origami paper based method

Sensing the Future-Frontiers in Biosensors: Exploring Classifications, Principles, and Recent Advances

Biosensors are transforming healthcare by delivering swift, precise, and economical diagnostic solutions. These analytical instruments combine biological indicators with physical transducers to identify and quantify biomarkers, thereby improving illness detection, management, and patient surveillance. Biosensors are widely utilized in healthcare for the diagnosis of chronic and infectious diseases, tailored treatment, and real-time health monitoring. This thorough overview examines several categories of biosensors and their uses in the detection of numerous biomarkers, including glucose, proteins, nucleic acids, and infections. Biosensors are commonly classified based on the type of transducer employed or the specific biorecognition element utilized. This review introduces a novel classification based on substrate morphology, offering a comprehensive perspective on biosensor categorization. Considerable emphasis is placed on the advancement of point-of-care biosensors, facilitating decentralized diagnostics and alleviating the strain on centralized healthcare systems. Recent advancements in nanotechnology have significantly improved the sensitivity, selectivity, and downsizing of biosensors, rendering them more efficient and accessible. The study examines problems such as stability, reproducibility, and regulatory approval that must be addressed to enable the widespread implementation of biosensors in clinical environments. The study examines the amalgamation of biosensors with wearable devices and smartphones, emphasizing the prospects for ongoing health surveillance and individualized medical care. This viewpoint clarifies the distinct types of biosensors and their particular roles, together with recent developments in the "smart biosensor" sector, facilitated by artificial intelligence and the Internet of Medical Things (IoMT). This novel approach seeks to deliver a comprehensive evaluation of the present condition of biosensor technology in healthcare, recent developments, and prospective paths, emphasizing their significance in influencing the future of medical diagnostics and patient care.

An innovative transportable immune device for the recognition of α-synuclein using KCC-1-nPr-CS2 modified silver nano-ink: integration of pen-on-paper technology with biosensing toward early-stage diagnosis of Parkinson's disease

Parkinson's disease (PD), the second most frequent neurodegenerative illness, is a neurological ailment that produces unintentional or uncontrolled body movements, which should be diagnosed in its early stages to hinder the progression. Monitoring the concentration of α-synuclein (α-Syn) in body fluids can be one of the most efficient ways for PD early detection. In this work, a paper-based electrochemical immunosensor was designed for α-Syn bio-assay in human plasma samples based on encapsulation of the biotinylated antibody on novel dendritic fibrous nanosilica ((KCC-1-nPr-CS2)-Ab). For this purpose, a three-electrode system was prepared using stabilization of silver nano-ink on photographic paper. Then, the (KCC-1-NH-CS2)-Ab was immobilized on its surface and used to detect the target antigen (α-Syn). After characterization of the prepared substrate by FE-SEM and EDS, the redox behavior of the biosensor was evaluated using chronoamperometry techniques. Under optimal experimental conditions and using a label-free strategy, the engineered immunosensor showed a linear relationship between peak current and antigen concentration in the linear range from 0.002 to 128 ng mL-1 with the lower limit of quantification of 0.002 ng mL-1. Moreover, this work involves unprecedented use of conductive nano-inks for the manufacture of α-Syn immunosensor, which is aided by the use of a mesoporous silicate dendrimer in encapsulating the α-Syn antibody, thus offering a robust and simple point-of-care device for early PD diagnosis. The ability of the proposed platform to detect small amounts of α-Syn offers a promising approach to developing low-cost, sensitive, and transportable biosensors for Parkinson's disease screening in its early stages.

Paper-Based Electrochemical Biosensors for Food Safety Analysis

Nowadays, foodborne pathogens and other food contaminants are among the major contributors to human illnesses and even deaths worldwide. There is a growing need for improvements in food safety globally. However, it is a challenge to detect and identify these harmful analytes in a rapid, sensitive, portable, and user-friendly manner. Recently, researchers have paid attention to the development of paper-based electrochemical biosensors due to their features and promising potential for food safety analysis. The use of paper in electrochemical biosensors offers several advantages such as device miniaturization, low sample consumption, inexpensive mass production, capillary force-driven fluid flow, and capability to store reagents within the pores of the paper substrate. Various paper-based electrochemical biosensors have been developed to enable the detection of foodborne pathogens and other contaminants that pose health hazards to humans. In this review, we discussed several aspects of the biosensors including different device designs (e.g., 2D and 3D devices), fabrication techniques, and electrode modification approaches that are often optimized to generate measurable signals for sensitive detection of analytes. The utilization of different nanomaterials for the modification of electrode surface to improve the detection of analytes via enzyme-, antigen/antibody-, DNA-, aptamer-, and cell-based bioassays is also described. Next, we discussed the current applications of the sensors to detect food contaminants such as foodborne pathogens, pesticides, veterinary drug residues, allergens, and heavy metals. Most of the electrochemical paper analytical devices (e-PADs) reviewed are small and portable, and therefore are suitable for field applications. Lastly, e-PADs are an excellent platform for food safety analysis owing to their user-friendliness, low cost, sensitivity, and a high potential for customization to meet certain analytical needs.

Metformin functionalized dendritic fibrous nanosilica (KCC-1-nPr-Met) as an innovative and green nanocatalyst for the efficient synthesis of tetrahydro-4H-chromene derivatives

An innovative nanocatalyst (KCC-1-nPr-Met) has been prepared from the covalent attachment of metformin on the channels and the pores of n-propyl amine functionalized dendritic fibrous nanosilica (DFNS) and used towards efficient, green, and high yield synthesis of tetrahydro-4H-chromenes derivatives by one-pot three-component reaction of aromatic aldehydes, malononitrile, and dimedone in H₂ O-EtOH at room temperature. The designed nanocatalyst has been characterized by energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR), and adsorption/desorption analysis (BET) techniques. Also, field emission scanning electron microscopy (FE-SEM) was used to study the morphology of prepared nanocatalyst. The engineered nanocatalyst with uniform fibrous spheres has dendritic structure, high pore volume (0.35 cm³ /g), and great surface area (178 m² /g). Hence, the specific dendritic structure of the prepared nanocatalyst not only improve the diffusion ability of the reactants and products, but also, increase the availability of dynamic sites in the pores and channels of the catalyst. According to the obtained results, a unique strategy was proposed towards the synthesis of important biologically active scaffolds in the presence of nontoxic and environmental friendly nanocatalyst and media. Milder reaction conditions (room temperature), shorter reaction times (5-30 minutes), excellent yields (92%-98%) of the products with higher purity, very simple workup procedure, and using of EtOH: H₂ O as a green solvent are the advantages of the presented work.

A flexible paper based electrochemical portable biosensor towards recognition of ractopamine as animal feed additive: Low cost diagnostic tool towards food analysis using aptasensor technology

Due to the costly and time-consuming traditional techniques, providing a low-cost, portability and flexibility diagnostic tool with the ability to monitor and detect various animal feed additive is highly demanded. Over the years, paper-based biosensors have emerged as point of care (POC) diagnostic, easy-to-use and miniaturized tools. However, they have been suffered from low sensitivity. Aptamer as appropriate bioreceptor can overcome the most common disadvantage of paper based sensor by increasing selectivity and sensitivity. In this study, a novel paper-based electrochemical aptasensor was successfully developed to detection of ractopamine (RAC). RAC concentration was evaluated using a designed three-electrode paper based biodevice system. Under the optimal experimental conditions, the engineered aptasensor provided good sensitivity and selectivity for the detection of RAC. Using proposed flexible sensor RAC was determined in the range of 0.001 µM to 100 mM which the lower limit of quantitation (LLOQ) was obtained as 0.01 µM. Finally, aptasensor was used to the monitoring of RAC in untreated human plasma specimens which LLOQ and linear range were 0.01 µM and 0.01 µM to 10 mM, respectively. We hope that the exploitation of aptamer in electrochemical paper based sensor will be able to broaden our understanding for developing the application of low-cost and portable biodevices for the sensitive and selective paper-based sensor to identify other chemical and biological compounds.

Electrochemical immunoplatform to assist in the diagnosis of oral cancer through the determination of CYFRA 21.1 biomarker in human saliva samples: Preparation of a novel portable biosensor toward non-invasive diagnosis of oral cancer

In this study, a novel, low-cost, and flexible paper-based electrochemical immunosensor was developed for the bioanalysis of Cyfra 21.1 biomarker in human saliva samples by using stabilization of synthesis Ag nano-ink on the surface of paper using pen-on-paper technology. The employed electrochemical techniques for the evaluation of immunoplatform performance were differential pulse voltammetry and chronoamperometry. Also, the prepared immunosensor showed great ability in the determination of Cyfra21.1 in human saliva specimens. Under the optimized conditions, the obtained linear range was from 0.0025 to 10 ng/mL, and the obtained LLOQ was 0.0025 ng/mL. The developed immunosensor is easy to prepare, sensitive, cost-effective, portable, and simple. So proposed immunoplatform can be an accomplished biodevice in clinical laboratories. The proposed paper-based immunosensor could be a hopefully new and cheap tool for the diagnosis of other biomarkers. Also, the prepared immunosensor showed great ability in the determination of Cyfra21.1 biomarker in human saliva specimens.

Recent advances of environmental pollutants detection via paper-based sensing strategy

Paper has become one of the most promising substrates for building low-cost and powerful sensing platforms due to its self-pumping ability and compatibility with multiple patterning methods. Paper-based sensors have been greatly developed in the field of environmental monitoring. In this review, we introduced the research and application of paper-based sensors in environmental monitoring, focusing on the deposition and patterning methods of building paper-based sensors, and summarized the applications of detecting environmental pollutants, including metal ions, anions, explosives, neurotoxins, volatile organic compounds, and small molecules. In addition, the development prospects and challenges of promoting paper-based sensors are also discussed. The current review will provide references for the construction of portable paper-based sensors, and has implications for the field of on-site real-time detection of the environment.

Electrochemical Affinity Assays/Sensors: Brief History and Current Status

The advent of electrochemical affinity assays and sensors evolved from pioneering efforts in the 1970s to broaden the field of analytes accessible to the selective and sensitive performance of electrochemical detection. The foundation of electrochemical affinity assays/sensors is the specific capture of an analyte by an affinity element and the subsequent transduction of this event into a measurable signal. This review briefly covers the early development of affinity assays and then focuses on advances in the past decade. During this time, progress on electroactive labels, including the use of nanoparticles, quantum dots, organic and organometallic redox compounds, and enzymes with amplification schemes, has led to significant improvements in sensitivity. The emergence of nanomaterials along with microfabrication and microfluidics technology enabled research pathways that couple the ease of use of electrochemical detection for the development of devices that are more user friendly, disposable, and employable, such as lab-on-a-chip, paper, and wearable sensors.

[Applications of microfluidic paper-based chips in environmental analysis and detection]

近年来,微流控纸芯片由于低成本、便携化、检测快等优点,在需要快速检测的环境分析领域中展现出了巨大的应用前景。该综述从微流控纸芯片在环境分析中的应用角度,总结归纳了微流控纸芯片在环境分析中的最新研究进展,并展望了其在未来的发展趋势与挑战。论文内容引用150余篇源于科学引文索引(SCI)与中文核心期刊中的相关论文。该综述包括微流控纸芯片在环境检测中的优势与制造方法介绍;电化学法、荧光法、比色法、表面增强拉曼法、集成传感法等基于纸芯片的先进分析方法介绍;根据环境分析目标物种类,如重金属离子、营养盐、农药、微生物、抗生素以及其他污染物等,对纸芯片的最新应用现状进行了举例评述;基于微流控纸芯片的环境分析研究的未来发展趋势和前景展望。通过综述近期相关研究,表明微流控纸芯片从提出至今虽然只有十几年的发展历程,但其在环境分析研究中的发展却十分迅速。微流控纸芯片可以根据不同的环境条件和检测要求灵活选择制作与分析方法,实现最佳的检测效果。但是微流控纸芯片也面临一些挑战,如纸张机械强度不足、流体控制程度不佳等问题。这些问题指出了微流控纸芯片在环境检测领域的发展趋势,相信随着不断深入的研究,纸芯片将会在未来的环境分析中发挥更大作用。

Label-free photoelectrochemical immunosensor for aflatoxin B1 detection based on the Z-scheme heterojunction of g-C3N4/Au/WO3

Aflatoxin B1 (AFB1) is the most toxic mycotoxin, is widely found in foods and animal feeds, and can pose a serious threat to our lives. A label-free photoelectrochemical (PEC) immunosensor was fabricated for the sensitive detection of AFB1. A Z-scheme heterojunction of gold nanoparticles (Au NPs) loaded on graphitic carbon nitride sheet and tungsten trioxide sphere composite (g-C₃N₄/Au/WO₃) acted as the highly sensitive platform. The g-C₃N₄/Au/WO₃ is capable, not only of immobilizing antibodies via Au NPs, but also enhancing the separation of electron-hole pairs due to its good energy band matching efficiency. The mechanism of photo-generated electron/hole transfer on g-C₃N₄/Au/WO₃ was explored using scavengers to eliminate active components. On this basis, an electron transfer pathway for the immunosensor was deduced. The PEC immunosensor displayed a linear concentration range from 1.0 pg mL^-1 to 100 ng mL^-1 and a low detection limit of 0.33 pg mL^-1 (S/N = 3) for AFB1. Good reproducibility, stability, and specificity provide a solid foundation for the practical application of this immunosensor.

Molecularly imprinted polymer-enhanced biomimetic paper-based analytical devices: A review

The popularization of paper-based analytical devices (PADs) in analytical science has fostered research on enhancing their analytical performance for accurate and sensitive assays. With their superb recognition capability and structural stability, molecularly imprinted polymers (MIPs) have been extensively employed as biomimetic receptors for capturing target analytes in various complex matrices. The integration of MIPs as recognition elements with PADs (MIP-PADs) has opened new opportunities for advanced analytical devices with elevated selectivity and sensitivity, as well as a shorter assay time and a lower cost. This review covers recent advances in MIP-PAD fabrication and engineering based on multifarious signal transduction systems such as colorimetry, fluorescence, electrochemistry, photoelectrochemistry, and chemiluminescence. The application of MIP-PADs in the fields of biomedical diagnostics, environmental analysis, and food safety monitoring is also reviewed. Further, the advantages, challenges, and perspectives of MIP-PADs are discussed.

Cytokine and Cancer Biomarkers Detection: The Dawn of Electrochemical Paper-Based Biosensor

Although the established ELISA-based sensing platforms have many benefits, the importance of cytokine and cancer biomarkers detection for point-of-care diagnostics has propelled the search for more specific, sensitive, simple, accessible, yet economical sensor. Paper-based biosensor holds promise for future in-situ applications and can provide rapid analysis and data without the need to conduct in a laboratory. Electrochemical detection plays a vital role in interpreting results obtained from qualitative assessment to quantitative determination. In this review, various factors affecting the design of an electrochemical paper-based biosensor are highlighted and discussed in depth. Different detection methods, along with the latest development in utilizing them in cytokine and cancer biomarkers detection, are reviewed. Lastly, the fabrication of portable electrochemical paper-based biosensor is ideal in deliberating positive societal implications in developing countries with limited resources and accessibility to healthcare services.

Bioassay of saliva proteins: The best alternative for conventional methods in non-invasive diagnosis of cancer

Non-invasive diagnosis of cancer is often the key to effective treatment and patient survival. Saliva as a multi-constituent oral fluid comprises various disease signaling biomarkers, holds great potential for early-stage cancer diagnostics with cost-effective and easy collection, storage, transport and processing. Therefore, detection of biomarkers and proteins in the saliva samples is highly demand. The current review was performed using reliable internet database (mainly PubMed) to provide an overview of the most recent developments on non-invasive diagnosis of cancers in saliva and highlights main challenges and future prospects in sensing of the salivary biomarkers. The conventional detection methods of cancer biomarkers in saliva is discussed in the paper, however, the main focus is on non-invasive diagnosis of cancers in saliva using immunosensing (electrochemical, optical, piezoelectric), DNA based sensors, aptasensors and peptide based bio-assays The reviewed literature revealed that non-invasive cancer detection methods using the mentioned biosensors and without any processing of saliva sample offers a quick, sensitive, specific and cost effective analytical tool. Besides, salivary based detection methods can be used for simultaneous detection of panels of disease specific biomarkers in a real time manner or as home testing kits in near future.

Bioassays: The best alternative for conventional methods in detection of Legionella pneumophila

Fastidious bacteria are group of bacteria that not only grow slowly but also have complex nutritional needs. In this review, recent progress made on development of biosensing strategies towards quantification of Legionella pneumophila as fastidious bacteria in microbiology was investigated. In coincidence with medical bacteriology, it is the most widely used bio-monitoring, biosensors based on DNA and antibody. Also, all of legionella pneumophila genosensors and immunosensors that developed in recent years were collected analyzed. This review is meant to provide an overview of the various types of bioassays have been developed for determination of Legionella Legionella, along with significant advances over the last several years in related technologies. In addition, this review described: i) Most frequently applied principles in bioassay/biosensing of Legionellaii) The aspects of fabrication in the perspective of bioassay/biosensing applications iii) The potential of various electrochemical and optical bioassay/biosensing for the determination of Legionella and the circumvention of the most serious problem in immunosensing/immunoassay was discussed. iv) Some of bioassay/biosensing has been discussed with and without labels. v) We also summarize the latest developments in the applications of bioassay/biosensing methods for detection of Legionella. vi) The development trends of optical and electrochemical based bioassay/biosensing are also introduced.

Trends in Paper-based Electrochemical Biosensors: From Design to Application

Electrochemical bio-sensing using paper-based detection systems is the main focus of this review. The different existing designs of 2-dimensional and 3-dimensional sensors, and fabrication techniques are discussed. This review highlights the effect of adopting different sensor designs, distinct fabrication techniques, as well as different modification methods, in order to produce reliable and reproducible reading. The use of various nanomaterials have been demonstrated in order to modify the surface of electrodes during fabrication to further enhance the signal for subsequent analysis. The reviewed sensors were classified into categories based on their applications, such as diagnostics, environmental and food testing. One of the major advantages of using paper-based electrochemical sensors is the potential for miniaturization, which only requires relatively small amount of samples, and the low cost for the purpose of mass production. Additionally, most of the devices reviewed were made to be portable, making them well-suited for on-site detection. Finally, paper-based detection is an ideal platform to fabricate cost-effective, user-friendly and sensitive electrochemical biosensors, with large capacity for customization depending on functional needs.

Ultrasensitive immunoassay of carcinoma antigen 125 in untreated human plasma samples using gold nanoparticles with flower like morphology: A new platform in early stage diagnosis of ovarian cancer and efficient management

Ovarian cancer, as one of the most life-threatening malignancies among women worldwide, is usually diagnosed at the late stage despite up regulation of molecular markers such as carcinoma antigen 125 (CA 125) at the early stages of the malignancy. CA 125 is the only tumor marker recommended for clinical use in the diagnosis and management of ovarian cancer. The potential role of CA-125 for the early detection of ovarian cancer is controversial and has not yet been adopted for widespread screening efforts in asymptomatic women. Therefore, early detection of CA 125 in human biofluids is highly demanded. In the present study, a novel method was proposed for the fabrication of electrochemical immunosensor based reduced graphene oxide (RGO). Cysteamine capped gold nanoparticle (Cys-AuNPs) were deposited over the surface of ERGO probe using electrophoretic deposition method. These Cys-AuNPs/ERGO probes provide the favorable sites to attach the monoclonal antibody specific to CA 125 antigen. Cyclic voltammetry (CV), and square wave voltammetry (SWV) were applied for the electrochemical recognition of the biolayer. The represented signals demonstrates excellent figure of merits and good capability of the engineered immunosensor towards sensitive detection of CA 125. Quantitative measurements of CA 125 in human plasma samples have been demonstrated, showing the potential of the practical application of this novel immunosensor for the analysis of this biomarker in blood serum samples. This immunosensor has the ability of direct electron transfer as compared to earlier reported electrochemical immunosensors based electrochemical methods. Further, this immunosensor provides a very suitable and convenient alternative to replace the expensive commercially available methods such as immunohistochemistry. The following regression equation between the electrochemical current response and the CA 125 concentration range from 0.1 to 400 U/mL was found. The low limit of quantification for this immunosensor was 0.1 U/mL. To the best of our knowledge, this is the first reported on the direct immobilization of antibody on the surface of Cys-AuNPs/ERGO for fabrication of immunosensors.

Ensuring food safety using aptamer based assays: Electroanalytical approach

Aptamers, are being increasingly employed as favorable receptors for constructing highly sensitive biosensors, for their remarkable affinities towards certain targets including a wide scope of biological or chemical substances, and their superiority over other biologic receptors. The selectivity and affinity of the aptamers have been integrated with the wise design of the assay, applying suitable modifications, such as nanomaterials on the electrode surface, employing oligonucleotide-specific amplification strategies or, their combinations. After successful performance of the electrochemical aptasensors for biomedical applications, the food sector with its direct implication for human health, which demands rapid and sensitive and economic analytical solutions for determination of health threatening contaminants in all stages of production process, is the next field of research for developing efficient electrochemical aptasensors. The aim of this review is to categorize and introduce food hazards and summarize the recent electrochemical aptasensors that have been developed to address these contaminants.

An innovative immunosensor for detection of tumor suppressor protein p53 in unprocessed human plasma and cancer cell lysates

An innovative mediator-free electrochemical immunosensor for quantitation of p53 tumor suppressor protein based on signal amplification strategy was fabricated. In this work, biotin conjugated p53-antibody (anti-p53) was immobilized onto a green and biocompatible nanocomposite containing poly l-cysteine (P-Cys) as conductive matrix and 3D gold nanoparticles (GNPs) as signal amplification element. Therefore, a novel nanocomposite film based on P-Cys and GNPs was exploited to develop a highly sensitive immunosensor for detection of p53 protein. Importantly, GNPs prepared by sonoelectrodeposition method which lead to compact morphology. Fully electrochemical methodology was used to prepare a new transducer on a gold surface which provided a high surface area to immobilize a high amount of the anti-p53. The surface morphology of electrode was characterized by high-resolution field emission scanning electron microscope (FE-SEM) and energy dispersive spectroscopy (EDX). The immunosensor was employed for the detection of p53 in physiological pH using square wav voltammetry and differential pulse voltammetry (DPVs) techniques. Under optimized condition the calibration curve for p53 concentration by SWV and DPV was linear in 0.0369-50pM and 0.018-2.5pM with lower limit of quantification of 48fM and 18fM, respectively. The method was successfully applied assay of the p53 in unprocessed human plasma samples. Also, the method was applied to the assay of p53 in human plasma sample and normal and malignant cell line lysates such as (L929 normal cell Line from mouse C3H (L929), colon cancer cell-HCT, prostate cancer cell line PC-3, and human breast adenocarcinoma cell line-MCF7).

Multiplexed Electrochemical Immunosensors for Clinical Biomarkers

Management and prognosis of disease requires the accurate determination of specific biomarkers indicative of normal or disease-related biological processes or responses to therapy. Moreover since multiple determinations of biomarkers have demonstrated to provide more accurate information than individual determinations to assist the clinician in prognosis and diagnosis, the detection of several clinical biomarkers by using the same analytical device hold enormous potential for early detection and personalized therapy and will simplify the diagnosis providing more information in less time. In this field, electrochemical immunosensors have demonstrated to offer interesting alternatives against conventional strategies due to their simplicity, fast response, low cost, high sensitivity and compatibility with multiplexed determination, microfabrication technology and decentralized determinations, features which made them very attractive for integration in point-of-care (POC) devices. Therefore, in this review, the relevance and current challenges of multiplexed determination of clinical biomarkers are briefly introduced, and an overview of the electrochemical immunosensing platforms developed so far for this purpose is given in order to demonstrate the great potential of these methodologies. After highlighting the main features of the selected examples, the unsolved challenges and future directions in this field are also briefly discussed.