Label-free electrochemical immunosensor for the detection of prostate specific antigen based three-dimensional Au nanoparticles/MoS2-graphene aerogels composite

Nanomaterials in Immunology: Bridging Innovative Approaches in Immune Modulation, Diagnostics, and Therapy

The intersection of immunology and nanotechnology has provided significant advancements in biomedical research and clinical applications over the years. Immunology aims to understand the immune system's defense mechanisms against pathogens. Nanotechnology has demonstrated its potential to manipulate immune responses, as nanomaterials' properties can be modified for the desired application. Research has shown that nanomaterials can be applied in diagnostics, therapy, and vaccine development. In diagnostics, nanomaterials can be used for biosensor development, accurately detecting biomarkers even at very low concentrations. Therapeutically, nanomaterials can act as efficient carriers for delivering drugs, antigens, or genetic material directly to targeted cells or tissues. This targeted delivery improves therapeutic efficacy and reduces the adverse effects on healthy cells and tissues. In vaccine development, nanoparticles can improve vaccine durability and extend immune responses by effectively delivering adjuvants and antigens to immune cells. Despite these advancements, challenges regarding the safety, biocompatibility, and scalability of nanomaterials for clinical applications are still present. This review will cover the fundamental interactions between nanomaterials and the immune system, their potential applications in immunology, and their safety and biocompatibility concerns.

Simultaneous immunodetection of multiple cervical cancer biomarkers based on a signal-amplifying redox probes/polyethyleneimine-coated gold nanoparticles/2D tungsten disulfide/graphene oxide nanocomposite platform

To advance cervical cancer diagnostics, we propose a state-of-the-art label-free electrochemical immunosensor designed for the simultaneous detection of multiple biomarker proteins (p16INK4a, p53, and Ki67). This immunosensor is constructed using a polyethyleneimine-coated gold nanoparticles/2D tungsten disulfide/graphene oxide (PEI-AuNPs/2D WS2/GO) composite-modified three-screen-printed carbon electrode (3SPCE) array. The 2D WS2/GO hybrid provides a large specific surface area for supporting well-dispersed PEI-AuNPs and adsorbed redox-active species, enhancing overall performance. The PEI-AuNPs-decorated 2D WS2/GO composite not only improves electrode conductivity but also increases the antibody loading capacity. Redox-active species, including Cd2+ ions, 2,3-diaminophenazine (DAP), and methylene blue (MB), serve as distinct signaling compounds to quantitatively detect the cervical cancer biomarkers p16INK4a, p53, and Ki67, respectively. Additionally, the immunosensor demonstrates the detection with high sensitivity, good storage stability, high selectivity, and acceptable reproducibility. This immunosensor demonstrates a good linear relationship with the logarithm of protein concentrations. Additionally, the immunosensor also demonstrates high sensitivity, good storage stability, high selectivity, and acceptable reproducibility. Our promising results and the successful application of the immunosensor in detecting three tumor markers in human serum highlight its potential for clinical diagnosis of cervical cancer.

Recent advances in biological molecule detection based on a three-dimensional graphene structure

Graphene has become an attractive material in the field of electrochemical detection owing to its unique electrical properties. Although the simple stacking structures of two-dimensional (2D) graphene sheets can provide excellent detection properties, a macroscopic three-dimensional (3D) structure needs to be constructed to enhance its functional properties. Graphene with a 3D structure has elegant functions, unlike graphene with a 2D structure. These properties include a large specific surface area, easy loading of nanomaterials with electrocatalytic and redox functions, and so on. Herein, we outline the preparation methods (self-assembly, chemical vapor deposition, templates, and 3D printing) for 3D graphene structures for obtaining excellent detection performance and applications in detecting biological molecules, bacteria, and cells. Furthermore, this review focuses on the improvement of the detection performance and enhancement of the applicability of graphene-based electrochemical sensors. We hope that this article will provide a reference for the future development of electrochemical sensors based on 3D graphene composites.

Point-of-care electrochemical testing of biomarkers involved in inflammatory and inflammatory-associated medical conditions

Recent years have shown that the diagnosis and monitoring of biomarkers involved in inflammatory-associated medical conditions such as cancer, neurological disorders, viral infections, or daily physical activities offer real benefits in increasing the quality of medical care and patient life quality. In this context, the use of integrated and portable platforms as point-of-care testing devices for biomedical analysis to enable early disease diagnosis and monitoring, which can be successfully used even at the patient's bed, is an emergency nowadays. The development of low-cost, miniaturized, and portable, user-friendly devices that provide an answer in a timely manner, such as electrochemical sensors, is relevant for the elaboration of point-of-care testing devices. This review focuses on the recent progress in bioanalysis of both specific biomarkers and inflammatory-associated biomarkers present in several diseases like neoplasia, severe neurological disorders, viral infections, and usual physical activity and provides an overview of the state of the art over the most recent electrochemical (bio)sensors for the detection of inflammation-related biomarkers. Future perspectives of point-of-care testing to improve healthcare management are also discussed.

Point-of-care biochemical assays using electrochemical technologies: approaches, applications, and opportunities

Against the backdrop of hidden symptoms of diseases and limited medical resources of their investigation, in vitro diagnosis has become a popular mode of real-time healthcare monitoring. Electrochemical biosensors have considerable potential for use in wearable products since they can consistently monitor the physiological information of the patient. This review classifies and briefly compares commonly available electrochemical biosensors and the techniques of detection used. Following this, the authors focus on recent studies and applications of various types of sensors based on a variety of methods to detect common compounds and cancer biomarkers in humans. The primary gaps in research are discussed and strategies for improvement are proposed along the dimensions of hardware and software. The work here provides new guidelines for advanced research on and a wider scope of applications of electrochemical biosensors to in vitro diagnosis.

Three-dimensional MoS2-graphene aerogel nanocomposites for electrochemical sensing of quercetin

A facile and novel electrochemical sensing platform is reported for quercetin determination with MoS₂ nanoflowers-3D graphene aerogel (3D MoS₂-GA) nanocomposite as signal amplified material. The 3D MoS₂-GA nanocomposite was synthesized through a two-step hydrothermal method, in which MoS₂ nanoflowers were prepared in advance. Characterizations of 3D MoS₂-GA were performed by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The 3D MoS₂-GA-modified glassy carbon electrode (3D MoS₂-GA/GCE) was used to investigate the electrochemical behaviors of quercetin with electrochemical parameters calculated, reaction mechanism discussed, and experimental conditions optimized. Notably, the redox peak current densities of quercetin on 3D MoS₂-GA/GCE raised 5.14 and 6.40 times compared with those on a bare GCE. Furthermore, a novel electroanalytical approach was proposed for the sensitive determination of quercetin within the concentration range 0.01 ~ 5.0 μmol/L, accompanied by a low detection limit of 0.0026 μmol/L (at a working potential of 0.38 V vs. Ag/AgCl). The recovery for practical sample analysis ranges from 97.0 to 105%, and the relative standard deviation is less than 4.2%. This established method shows reliable performance in determination of quercetin in tablets and urine samples.

Biosensing strategies for diagnosis of prostate specific antigen

Almost from the time of its discovery, the prostate specific antigen (PSA) has been one of the most accurate and most extensively studied indicators of prostate cancer (PC). Because of advancements in biosensing systems and technology, PSA analysis methods have been substantially updated and enhanced as compared to their first instances. With the development of techniques in biosensor technology, the number of PSA biosensors that can be used in the biomedical sector is increasing year by year. Many different recognition elements and transducers have been used in the development of biosensor systems that exhibit high sensitivity, selectivity, and specificity. Here in this review, we provide a current overview of the different approaches to PSA detection.

Electrochemical detection of matrix metalloproteinase-7 using an immunoassay on a methylene blue/2D MoS2/graphene oxide electrode

Methylene blue (MB) adsorption onto a two-dimensional molybdenum disulfide (2D MoS₂)/graphene oxide (GO) nanocomposite sitting on a screen-printed carbon electrode (SPCE) is used to develop a new sensitive label-free electrochemical immunosensor for the detection of matrix metalloproteinase-7 (MMP-7) cancer biomarkers. The 2D MoS₂/GO nanocomposite deposited onto an SPCE provides a large specific surface area, fast electron transfer, and exceptional electrical conductivity. Furthermore, MB adsorbed onto the 2D MoS₂/GO nanocomposite architecture can be used for signal amplification in electrochemical immunosensors. Moreover, an immunosensor platform was fabricated by the adsorption of anti-MMP-7 capture antibodies onto the MB/2D MoS₂/GO nanocomposite surface via electrostatic interactions for the detection of the MMP-7 immunocomplex. Under optimum conditions, the label-free immunosensor exhibits a decrease in the current response for MB corresponding to the MMP-7 concentration. The sensor affords a linear logarithmic range of 0.010-75 ng mL^-1 with a limit of detection (LOD) of 0.007 ng mL^-1. The developed electrochemical immunosensor provides high selectivity, good reproducibility, and excellent stability. Furthermore, the proposed immunosensor can be applied for the detection of MMP-7 in human serum samples with good recovery. Thus, this device can be applied for the early clinical diagnosis of pancreatic and colorectal cancers.

Construction of a Label-Free Electrochemical Immunosensor Based on Zn-Co-S/Graphene Nanocomposites for Carbohydrate Antigen 19-9 Detection

Nanocomposites of the binary transition metal sulfide Zn-Co-S/graphene (Zn-Co-S@G) were synthesized through a one-step hydrothermal method. They may be useful in the construction of an electrochemical immunosensor for carbohydrate antigen 19-9 (CA19-9) detection. Zn-Co-S dot-like nanoparticles uniformly covered the surface of graphene to form an interconnected conductive network, ensuring strong interaction between transition metal sulfide and graphene, which can expose numerous electroactive sites leading to the improvement of the amplified electrochemical signal toward a direct reduction of H2O2. Thus, the construction of an electrochemical immunosensor using Zn-Co-S@G nanocomposites showed outstanding sensing properties for detecting CA19-9. The constructed electrochemical immunosensor exhibited a good linear relationship in the range of 6.3 U·mL-1-300 U·mL-1, with the limit of detection at 0.82 U·mL-1, which makes it a promising candidate for an electrochemical immunosensor.

A Bifunctional Nanosilver-Reduced Graphene Oxide Nanocomposite for Label-Free Electrochemical Immunosensing

A bi-functional material based on silver nanoparticles (AgNPs)-reduced graphene oxide (rGO) composite for both electrode modification and signal generation is successfully synthesized for use in the construction of a label-free electrochemical immunosensor. An AgNPs/rGO nanocomposite is prepared by a one-pot wet chemical process. The AgNPs/rGO composite dispersion is simply cast on a screen-printed carbon electrode (SPCE) to fabricate the electrochemical immunosensor. It possesses a sufficient conductivity/electroreactivity and improves the electrode reactivity of SPCE. Moreover, the material can generate an analytical response due to the formation of immunocomplexes for detection of human immunoglobulin G (IgG), a model biomarker. Based on electrochemical stripping of AgNPs, the material reveals signal amplification without external redox molecules/probes. Under optimized conditions, the square wave voltammetric peak current is responded to the logarithm of IgG concentration in two wide linear ranges from 1 to 50 pg.ml-1 and 0.05 to 50 ng.ml-1, and the limit of detection (LOD) is estimated to be 0.86 pg.ml-1. The proposed immunosensor displays satisfactory sensitivity and selectivity. Importantly, detection of IgG in human serum using the immunosensor shows satisfactory accuracy, suggesting that the immunosensor possesses a huge potential for further development in clinical diagnosis.

Development of Highly Sensitive Immunosensor for Detection of Staphylococcus aureus Based on AuPdPt Trimetallic Nanoparticles Functionalized Nanocomposite

The rapid and sensitive detection of Staphylococcus aureus (S. aureus) is essential to ensure food safety and protect humans from foodborne diseases. In this study, a sensitive and facile electrochemical immunosensor using AuPdPt trimetallic nanoparticles functionalized multi-walled carbon nanotubes (MWCNTs-AuPdPt) as the signal amplification platform was designed for the label-free detection of S. aureus. The nanocomposite of MWCNTs-AuPdPt was prepared by an in situ growth method of loading AuPdPt trimetallic nanoparticles on the surface of MWCNTs. The synthesized MWCNTs-AuPdPt featured good conductivity and superior catalytic performance for hydrogen peroxide. The nanocomposite of MWCNTs-AuPdPt with good biocompatibility and high specific surface area was further functionalized by anti-S. aureus antibodies. The immobilized antibodies could efficiently capture S. aureus to the modified electrode by an immune reaction, which resulted in the change of catalytic current intensity to realize the sensitive detection of S. aureus. The designed immunosensor could detect S. aureus in a linear range from 1.1 × 102 to 1.1 × 107 CFU mL-1 with a low detection limit of 39 CFU mL-1. Additionally, the proposed immunosensor was successfully applied to determine S. aureus in actual samples with acceptable results. This strategy provided a promising platform for highly sensitive determination of S. aureus and other pathogens in food products.

Electrochemical immunosensor based on Au/Co-BDC/MoS2 and DPCN/MoS2 for the detection of cardiac troponin I

The content of cardiac troponin I (CTnI) in human blood is the key factor in judging acute myocardial infarction (AMI). In order to detect the content of CTnI, we constructed a sandwich-type electrochemical immunosensor based on hydrogen peroxide (H₂O₂) as a signal source. Dendritic platinum-copper alloy nanoparticles (DPCN) loaded on molybdenum disulfide (MoS₂) nanosheets (DPCN/MoS₂) as secondary antibodies (Ab₂) label provided signal amplification. The hollow three-dimensional (3D) pyramid-shaped structure of DPCN exposed abundant active sites and exhibited excellent catalytic properties. MoS₂ nanosheets with flower-like structure and a larger specific surface area can effectively load more DPCN. The combination of MoS₂ and DPCN enhanced the catalytic performance of DPCN/MoS₂ towards H₂O₂ reduction and realized signal amplification. For the substrate material, the two-dimensional (2D) metal-organic framework (Co-BDC, 1,4-benzenedicarboxylate is abbreviated as BDC) was hybridized with MoS₂ nanosheets to load gold nanoparticles (Au NPs). The obtained Au/Co-BDC/MoS₂ had low catalytic activity and excellent electrical conductivity, which was used to load primary antibodies (Ab₁) to effectively enhance the sensitivity. Under the best conditions, we constructed the immunosensor with the detection range of 10 fg/mL to 100 ng/mL and the limit of detection (LOD) of 3.02 fg/mL. At the same time, the content of CTnI in human serum was tested with satisfactory results. Therefore, the constructed immunosensor has important significance in the sensitive and accurate detection of CTnI and early diagnosis of AMI.

Metal Nanoparticles for Electrochemical Sensing: Progress and Challenges in the Clinical Transition of Point-of-Care Testing

With the rise in public health awareness, research on point-of-care testing (POCT) has significantly advanced. Electrochemical biosensors (ECBs) are one of the most promising candidates for the future of POCT due to their quick and accurate response, ease of operation, and cost effectiveness. This review focuses on the use of metal nanoparticles (MNPs) for fabricating ECBs that has a potential to be used for POCT. The field has expanded remarkably from its initial enzymatic and immunosensor-based setups. This review provides a concise categorization of the ECBs to allow for a better understanding of the development process. The influence of structural aspects of MNPs in biocompatibility and effective sensor design has been explored. The advances in MNP-based ECBs for the detection of some of the most prominent cancer biomarkers (carcinoembryonic antigen (CEA), cancer antigen 125 (CA125), Herceptin-2 (HER2), etc.) and small biomolecules (glucose, dopamine, hydrogen peroxide, etc.) have been discussed in detail. Additionally, the novel coronavirus (2019-nCoV) ECBs have been briefly discussed. Beyond that, the limitations and challenges that ECBs face in clinical applications are examined and possible pathways for overcoming these limitations are discussed.