Electrochemiluminescence paper-based screen-printed electrode for HbA1c detection using two-dimensional zirconium metal-organic framework/Fe3O4 nanosheet composites decorated with Au nanoclusters

Recent advances in gold nanostructure-based biosensors in detecting diabetes biomarkers

Diabetes mellitus (DM) is a prevalent disorder with an urgent need for continuous, precise, and on-site biomarker monitoring devices. The continuous monitoring of DM biomarkers from different biological matrices will become routine in the future, thanks to the promising biosensor design. Lately, employing different nanomaterials in biosensor receptor parts has had a great impact on smart DM monitoring. Among them, gold nanostructures (AuNSs) have arisen as highly potential materials in fabricating precise DM biosensors due to their unique properties. The present study provides an update on the applications of AuNSs in biosensors for detecting glucose as well as other DM biomarkers, such as glycated hemoglobin (HbA1c), glycated albumin (GA), insulin, insulin antibodies, uric acid, lactate, and glutamic acid decarboxylase antibodies (GADA), with a focus on the most important factors in biosensor performance such as sensitivity, selectivity, response time, and stability. Specified values of limit of detection (LOD), linear concentrations, reproducibility%, recovery%, and assay time were used to compare studies. In conclusion, AuNSs, owing to the wide electrochemical potential window and low electrical resistivity, are valuable tools in biosensor design, alongside other biological reagents and/or nanomaterials.

A comprehensive review of the application of Zr-based metal-organic frameworks for electrochemical sensors and biosensors

A family of inorganic-organic hybrid crystalline materials made up of organic ligands and metal cations or clusters is known as metal-organic frameworks (MOFs). Because of their unique stability, intriguing characteristics, and structural diversity, zirconium-based MOFs (Zr-MOFs) are regarded as one of the most interesting families of MOF materials for real-world applications. Zr-MOFs that have the ligands, metal nodes, and guest molecules enclosed show distinct electrochemical reactions. They can successfully and sensitively identify a wide range of substances, which is important for both environmental preservation and human health. The rational design and synthesis of Zr-MOF electrochemical sensors and biosensors, as well as their applications in the detection of drugs, biomarkers, pesticides, food additives, hydrogen peroxide, and other materials, are the main topics of this comprehensive review. We also touch on the current issues and potential future paths for Zr-MOF electrochemical sensor research.

Emerging biosensor probes for glycated hemoglobin (HbA1c) detection

Glycated hemoglobin (HbA1c), originating from the non-enzymatic glycosylation of βVal1 residues in hemoglobin (Hb), is an essential biomarker indicating average blood glucose levels over a period of 2 to 3 months without external environmental disturbances, thereby serving as the gold standard in the management of diabetes instead of blood glucose testing. The emergence of HbA1c biosensors presents affordable, readily available options for glycemic monitoring, offering significant benefits to small-scale laboratories and clinics. Utilizing nanomaterials coupled with high-specificity probes as integral components for recognition, labeling, and signal transduction, these sensors demonstrate exceptional sensitivity and selectivity in HbA1c detection. This review mainly focuses on the emerging probes and strategies integral to HbA1c sensor development. We discussed the advantages and limitations of various probes in sensor construction as well as recent advances in diverse sensing strategies for HbA1c measurement and their potential clinical applications, highlighting the critical gaps in current technologies and future needs in this evolving field.

A three-in-one point-of-care electrochemical sensing platform for accurate monitoring of diabetes

A three-in-one electrochemical sensing platform was designed for the simultaneous detection of total hemoglobin (tHb), glycated hemoglobin (HbA1c) and HbA1c% by using a dual-aptamer sensing strategy. The developed sensing platform exhibits excellent sensitivity, selectivity, repeatability and long-term stability, and holds promising prospects in the early diagnosis and long-term monitoring of diabetes.

The luminescent principle and sensing mechanism of metal-organic framework for bioanalysis and bioimaging

Metal-organic frameworks (MOFs) porous material have obtained more and more attention during the past decade. Among various MOFs materials, luminescent MOFs with specific chemical characteristics and excellent optical properties have been regarded as promising candidates in the research of cancer biomarkers detection and bioimaging. Therefore, the latest advances and the principal biosensing and imaging strategies based on the luminescent MOFs were discussed in this review. The effective synthesis methods of luminescent MOFs were emphasized firstly. Subsequently, the luminescent principle of MOFs has been summarized. Furthermore, the luminescent MOF-based sensing mechanisms have been highlighted to provide insights into the design of biosensors. The designability of LMOFs was suitable for different needs of biorecognition, detection, and imaging. Typical examples of luminescent MOF in the various cancer biomarkers detection and bioimaging were emphatically introduced. Finally, the future outlooks and challenges of luminescent MOF-based biosensing systems were proposed for clinical cancer diagnosis.

Advancing piezoelectric 2D nanomaterials for applications in drug delivery systems and therapeutic approaches

Precision drug delivery and multimodal synergistic therapy are crucial in treating diverse ailments, such as cancer, tissue damage, and degenerative diseases. Electrodes that emit electric pulses have proven effective in enhancing molecule release and permeability in drug delivery systems. Moreover, the physiological electrical microenvironment plays a vital role in regulating biological functions and triggering action potentials in neural and muscular tissues. Due to their unique noncentrosymmetric structures, many 2D materials exhibit outstanding piezoelectric performance, generating positive and negative charges under mechanical forces. This ability facilitates precise drug targeting and ensures high stimulus responsiveness, thereby controlling cellular destinies. Additionally, the abundant active sites within piezoelectric 2D materials facilitate efficient catalysis through piezochemical coupling, offering multimodal synergistic therapeutic strategies. However, the full potential of piezoelectric 2D nanomaterials in drug delivery system design remains underexplored due to research gaps. In this context, the current applications of piezoelectric 2D materials in disease management are summarized in this review, and the development of drug delivery systems influenced by these materials is forecast.

Lateral Flow Assay: A Summary of Recent Progress for Improving Assay Performance

Lateral flow tests are one of the most important types of paper-based point-of-care (POCT) diagnostic tools. It shows great potential as an implement for improving the rapid screening and management of infections in global pandemics or other potential health disorders by using minimally expert staff in locations where no sophisticated laboratory services are accessible. They can detect different types of biomarkers in various biological samples and provide the results in a little time at a low price. An important challenge regarding conventional LFAs is increasing their sensitivity and specificity. There are two main approaches to increase sensitivity and specificity, including assay improvement and target enrichment. Assay improvement comprises the assay optimization and signal amplification techniques. In this study, a summarize of various sensitivity and specificity enhancement strategies with an objective evaluation are presented, such as detection element immobilization, capillary flow rate adjusting, label evolution, sample extraction and enrichment, etc. and also the key findings in improving the LFA performance and solving their limitations are discussed along with numerous examples.

Naked-Eye Readout Distance Quantitative Lateral Flow Assay Based on the Permeability Changes of Enzyme-Catalyzed Hydrogelation

Traditional lateral flow assay (LFA) is restricted to providing qualitative or semi-quantitative results and often requires special equipment for obtaining quantitative results. Herein, we proposed a naked-eye readout distance quantitative lateral flow assay based on the permeability changes in enzyme-catalyzed hydrogelation, which not only has the advantages of being simple, immediate, of high efficiency and low cost, and accurate in quantification but also avoids the use of special equipment. The developed LFA method includes three principal components of a nitrocellulose (NC) membrane containing a control line (C line) loading goat anti-rabbit (GAR) antibodies and a test line (T line) loading specific antibodies, alginate-tyramine conjugates forming a hydrogel in the presence of hydrogen peroxide (H₂O₂) and horseradish peroxidase (HRP), and the HRP-AuNPs-Ab probe only labeling targets captured on the T line. Hemoglobin A1c (HbA1c) was chosen as a representative example to demonstrate the feasibility of our method. Under the optimal conditions, the developed LFA method shows excellent performance in standard samples and real human blood samples where the results of real human blood samples show a high linear correlation with the clinical data obtained by ion exchange chromatography (R² = 0.9929) and the margin of recovery is only 3.8%. All results demonstrated that our developed LFA method not only has enormous potential in the quantitative detection of HbA1c in clinical complex samples but also can serve as a versatile method for highly efficient detection of other target biomolecules due to the fungibility of antibodies.

A label-free multicolor colorimetric and fluorescence dual mode biosensing of HIV-1 DNA based on the bifunctional NiFe2O4@UiO-66 nanozyme

Finding the DNA of the human immune deficiency virus (HIV) with simple and sensitive detection is the main challenge in early diagnosis of AIDS. Herein, two-point separation strategies based on the colorimetric and fluorescence are introduced. The naked-eye qualitative and semiquantitative colorimetric, and also accuracy fluorescence quantification of HIV-1 DNA were applied using label-free NiFe₂O₄@UiO-66 nanozyme with both functions of peroxidase-mimetic like and emitting fluorescence. The DNA probe-conjugated nanozyme is employed to hybridize a sequence of HIV-1. NiFe₂O₄@UiO-66 nanozymes catalyze the decomposition of H₂O₂ to ^•OH which can produce a remarkable fluorescent product 2-hydroxyterephthalic acid (TAOH) by the oxidation of the bridging ligand of weakly fluorescent terephthalic acid (TA). The accessibility of H₂O₂ toward confined-NiFe₂O₄ MNPs was reduced by increasing the HIV-1 target DNA concentration, resulting in the fluorescence intensity of TAOH being decreased. Meanwhile, remaining the unreacted H₂O₂ was transferred an acidic colorimetric solution containing FeSO₄ and gold nanorods (AuNRs). Increasing the amount of H₂O₂ available for longitudinal etching of AuNRs due to •OH-generating Fe⁺²-catalyzed H₂O₂ is reponsible for different colors from brownish to colorless depending on the HIV-1 target DNA concentration. The fluorescence intensity and obtained colors have offered the sensitive biosensing methods with a linear range from 0.05 to 300 and 1-200 pM, respectively with a detection limit as low as 1 fM. Our study revealed that the applied sensing assay provides a cost-effective and straightforward qualitative, semiquantitative, and sensitive quantitation visible monitoring without the necessity of high-end instruments for HIV-1 detection in a human blood plasma/serum samples.

Trends in Paper-Based Sensing Devices for Clinical and Environmental Monitoring

Environmental toxic pollutants and pathogens that enter the ecosystem are major global issues. Detection of these toxic chemicals/pollutants and the diagnosis of a disease is a first step in efficiently controlling their contamination and spread, respectively. Various analytical techniques are available to detect and determine toxic chemicals/pathogens, including liquid chromatography, HPLC, mass spectroscopy, and enzyme-linked immunosorbent assays. However, these sensing strategies have some drawbacks such as tedious sample pretreatment and preparation, the requirement for skilled technicians, and dependence on large laboratory-based instruments. Alternatively, biosensors, especially paper-based sensors, could be used extensively and are a cost-effective alternative to conventional laboratory testing. They can improve accessibility to testing to identify chemicals and pollutants, especially in developing countries. Due to its low cost, abundance, easy disposal (by incineration, for example) and biocompatible nature, paper is considered a versatile material for the development of environmentally friendly electrochemical/optical (bio) sensor devices. This review presents an overview of sensing platforms constructed from paper, pointing out the main merits and demerits of paper-based sensing systems, their fabrication techniques, and the different optical/electrochemical detection techniques that they exploit.

Toward waterborne protozoa detection using sensing technologies

Drought and limited sufficient water resources will be the main challenges for humankind during the coming years. The lack of water resources for washing, bathing, and drinking increases the use of contaminated water and the risk of waterborne diseases. A considerable number of waterborne outbreaks are due to protozoan parasites that may remain active/alive in harsh environmental conditions. Therefore, a regular monitoring program of water resources using sensitive techniques is needed to decrease the risk of waterborne outbreaks. Wellorganized point-of-care (POC) systems with enough sensitivity and specificity is the holy grail of research for monitoring platforms. In this review, we comprehensively gathered and discussed rapid, selective, and easy-to-use biosensor and nanobiosensor technologies, developed for the early detection of common waterborne protozoa.

Portable paper-based electrochemiluminescence test incorporating lateral-flow immunosensors for detection of interferon-γ levels

Tuberculosis (TB) poses a serious threat to human health and social development. Accurate diagnosis of mycobacterium tuberculosis infection plays a critical role in the prevention and treatment of tuberculosis. Interferon-γ (INF-γ) release assay (IGRA) is currently the only quantitative tuberculosis infection diagnosis method. An accurate, fast, and easily handled INF-γ detection method is the key to obtaining accurate results. Herein, we report a novel paper-based electrochemiluminescence (ECL) method based on lateral flow immunosensors that combines the easy handling characteristics of immunochromatography and the high sensitivity of electrochemiluminescence to detect IFN-γ. To our knowledge this is the first INF-γ detection method that combines immunochromatography with electrochemiluminescence. The paper-based ECL-LFI test consists of a sample pad, conjugation pad (with binding antibody IFN-γ-Ab1 conjugated with ruthenium tripyridine), detection pad (with capture antibody IFN-γ-Ab2 immobilized on nanospheres), absorbent pad, and electrode for signal activation. The ECL signal is obtained by cyclic voltammetry scanning at a speed of 0.1 V/s in the detection area of the paper-based ECL-LFI test. In our experiments, the paper-based ECL-LFI test exhibited a minimum detection limit of 2.57 pg/mL within 12 min, and a broad detection range of 2.57-5,000 pg/mL, with repeatability of 8.10% and stability of 4.97%. With the advantage of high accuracy and sensitivity, easy handling, and low user training requirements, this ECL-LFI test might be used as point-of-care testing (POCT) in the IGRA for tuberculosis diagnosis.

Tungsten Disulfide Decorated Screen-Printed Electrodes for Sensing of Glycated Hemoglobin

Diabetes is a global menace, and its severity results in various disorders including cardiovascular, retinopathy, neuropathy, and nephropathy. Recently, diabetic conditions are diagnosed through the level of glycated hemoglobin. The level of glycated hemoglobin is determined with enzymatic methodology. Although the system is sensitive, it has various restrictions such as long processing times, expensive equipment required for testing, and complex steps involved in sample preparation. These limitations are a hindrance to faster results. The limitations of the developed methods can be eliminated through biosensors. In this work, an electrochemical platform was fabricated that facilitates the identification of glycated hemoglobin protein in diabetic patients. The working electrode on the integrated circuit was modified with molecularly imprinted polymer decorated with tungsten disulfide nanoparticles to enhance its analytical properties. The analytical properties of the biosensor were studied using electrochemical techniques. The obtained detection limit of the nanoelectronic sensor was 0.01 pM. The calculated sensitivity of the biosensor was observed to be 0.27 μA/pM. Also, the sensor promises to operate in a dynamic working concentration range and provide instant results.

Application of Metal–Organic Framework in Diagnosis and Treatment of Diabetes

Diabetes-related chronic wounds are often accompanied by a poor wound-healing environment such as high glucose, recurrent infections, and inflammation, and standard wound treatments are fairly limited in their ability to heal these wounds. Metal–organic frameworks (MOFs) have been developed to improve therapeutic outcomes due to their ease of engineering, surface functionalization, and therapeutic properties. In this review, we summarize the different synthesis methods of MOFs and conduct a comprehensive review of the latest research progress of MOFs in the treatment of diabetes and its wounds. State-of-the-art in vivo oral hypoglycemic strategies and the in vitro diagnosis of diabetes are enumerated and different antimicrobial strategies (including physical contact, oxidative stress, photothermal, and related ions or ligands) and provascular strategies for the treatment of diabetic wounds are compared. It focuses on the connections and differences between different applications of MOFs as well as possible directions for improvement. Finally, the potential toxicity of MOFs is also an issue that we cannot ignore.

Research Progress and Future Trends of Microfluidic Paper-Based Analytical Devices in In-Vitro Diagnosis

In vitro diagnosis (IVD) has become a hot topic in laboratory research and achievement transformation. However, due to the high cost, and time-consuming and complex operation of traditional technologies, some new technologies are being introduced into IVD, to solve the existing problems. As a result, IVD has begun to develop toward point-of-care testing (POCT), a subdivision field of IVD. The pandemic has made governments and health institutions realize the urgency of accelerating the development of POCT. Microfluidic paper-based analytical devices (μPADs), a low-cost, high-efficiency, and easy-to-operate detection platform, have played a significant role in advancing the development of IVD. μPADs are composed of paper as the core material, certain unique substances as reagents for processing the paper, and sensing devices, as auxiliary equipment. The published reviews on the same topic lack a comprehensive and systematic introduction to μPAD classification and research progress in IVD segmentation. In this paper, we first briefly introduce the origin of μPADs and their role in promoting IVD, in the introduction section. Then, processing and detection methods for μPADs are summarized, and the innovative achievements of μPADs in IVD are reviewed. Finally, we discuss and prospect the upgrade and improvement directions of μPADs, in terms of portability, sensitivity, and automation, to help researchers clarify the progress and overcome the difficulties in subsequent μPAD research.

Recent progress of metal nanoclusters in electrochemiluminescence

Metal nanoclusters (MeNCs), composed of a few to hundreds of metal atoms and appropriate surface ligands, have attracted extensive interest in the electrochemiluminescence (ECL) realm owing to their molecule-like optical, electronic, and physicochemical attributes and are strongly anticipated for discrete energy levels, fascinating electrocatalytic activity, and good biocompatibility. Over the past decade, huge efforts have been devoted to the synthesis, properties, and application research of ECL-related MeNCs, and this field is still a subject of heightened concern. Therefore, this perspective aims to provide a comprehensive overview of the recent advances of MeNCs in the ECL domain, mainly covering the emerged ECL available MeNCs, unique chemical and optical properties, and the general ECL mechanisms. Synthesis strategies for desirable ECL performance are further highlighted, and the resulting ECL sensing applications utilizing MeNCs as luminophores, quenchers, and substrates are discussed systematically. Finally, we anticipate the future prospects and challenges in the development of this area.

Smartphone-Based Electrochemiluminescence for Visual Simultaneous Detection of RASSF1A and SLC5A8 Tumor Suppressor Gene Methylation in Thyroid Cancer Patient Plasma

Visual one-step simultaneous detection of low-abundance methylation is a crucial challenge in early cancer diagnosis in a simple manner. Through the design of a closed split bipolar electrochemistry system (BE), detection of promoter methylation of tumor suppressor genes in papillary thyroid cancer, RASSF1A and SLC5A8, was achieved using electrochemiluminescence. For this purpose, electrochemiluminescence of luminol loaded into the Fe₃O₄@UiO-66 and gold nanorod-functionalized graphite-like carbon nitride nanosheet (AuNRs@C₃N₄ NS), separately, on the anodic and cathodic pole bipolar electrodes (BPEs) in two different chambers of a bipolar cell were recorded on a smartphone camera. To provide the same electric potential (ΔE_elec) through the BPEs to conduct simultaneous light emission, as well as to achieve higher sensitivity, anodic and cathodic poles BPEs were separately connected to ruthenium nanoparticles electrodeposited on nitrogen-doped graphene-coated Cu foam (fCu/N-GN/RuNPs) to provide a hydrogen evolution reaction (HER) and polycatechol-modified reduced graphene oxide/pencil graphite electrode (PC-rGO/PGE) to provide electrooxidation of hydrazine. Moreover, taking advantages of the strong cathodic ECL activity due to the roles of AuNRs, as well as the high density of capture probes on the UiO-66 and Fe₃O₄ roles in improving the signal-to-background ratio (S/B) in complicated plasma media, a sensitive visual ECL immunosensor was developed to detect two different genes as model target analytes in patient plasma samples. The ability of discrimination of methylation levels as low as 0.01% and above 90% clinical sensitivity in thyroid cancer patient plasma implies that the present strategy is able to diagnose cancer early, as well as monitor responses of patients to therapeutic agents.

Electrochemical immunosensor for determination of cardiac troponin I using two-dimensional metal-organic framework/Fe3O4-COOH nanosheet composites loaded with thionine and pCTAB/DES modified electrode

Cardiac troponin-I (CTnI) is one of the most popular biomarkers which can be utilized for the diagnosis and control of acute myocardial infarction in clinical practice. Here, a sandwich-type electrochemical immunosensor has been established using the zinc-based metal-organic framework/Fe₃O₄-COOH/thionine labeled anti-CTnI monoclonal antibody (Ab₁-Zn-MOF/Fe₃O₄-COOH/Thi) nanocomposite as signaling molecule and a polymer film of cetyltrimethylammonium bromide (pCTAB) in the presence of choline chloride-urea deep eutectic solvent (DES) and anti-CTnI polyclonal antibody (Ab₂) as immobilization substance of detecting surface. The porous ultrathin layers of Zn-MOF nanosheets successfully prepare a well-defined structure for Fe₃O₄-COOH electrocatalyst and Thi within a certain two dimensional (2D) regions, which enhances electrochemical reduction of Thi. The Ab₁-Zn-MOF/Fe₃O₄-COOH/Thi nanocomposites were introduced to CTnI in the specimen and on the surface of pCTAB/DES-Au-SPE quantitative determination of CTnI was achieved using differential pulse voltammetry after sandwiching the CTnI target between Ab₁-nanocomposite and Ab₂ which was encapsulated into the pCTAB/DES-Au-SPE. This immunosensor indicated the appropriate assay performance for CTnI with the detection range of 0.04 ng mL^-1 to 50 ng mL^-1 and the limit of detection of 0.0009 ng mL^-1. This study provides convenient plan for sensitive detection of bioanalytes and opens a path for the establishment of user-friendly and cost-effective device.

Advances in Nanomaterial-based Biosensors for Determination of Glycated Hemoglobin

Diabetes is a major public health burden whose prevalence has been steadily increasing over the past decades. Glycated hemoglobin (HbA1c) is currently the gold standard for diagnostics and monitoring of glycemic control in diabetes patients. HbA1c biosensors are often considered to be cost-effective alternatives for smaller testing laboratories or clinics unable to access other reference methods. Many of these sensors deploy nanomaterials as recognition elements, detection labels, and/or transducers for achieving sensitive and selective detection of HbA1c. Nanomaterials have emerged as important sensor components due to their excellent optical and electrical properties, tunable morphologies, and easy integration into multiple sensing platforms. In this review, we discuss the advantages of using nanomaterials to construct HbA1c sensors and various sensing strategies for HbA1c measurements. Key gaps between the current technologies with what is needed moving forward are also summarized.