Engineered two-dimensional nanomaterials based diagnostics integrated with internet of medical things (IoMT) for COVID-19.

More than four years have passed since an inimitable coronavirus disease (COVID-19) pandemic hit the globe in 2019 after an uncontrolled transmission of the severe acute respiratory syndrome (SARS-CoV-2) infection. The occurrence of this highly contagious respiratory infectious disease led to chaos and mortality all over the world. The peak paradigm shift of the researchers was inclined towards the accurate and rapid detection of diseases. Since 2019, there has been a boost in the diagnostics of COVID-19 via numerous conventional diagnostic tools like RT-PCR, ELISA, etc., and advanced biosensing kits like LFIA, etc. For the same reason, the use of nanotechnology and two-dimensional nanomaterials (2DNMs) has aided in the fabrication of efficient diagnostic tools to combat COVID-19. This article discusses the engineering techniques utilized for fabricating chemically active E2DNMs that are exceptionally thin and irregular. The techniques encompass the introduction of heteroatoms, intercalation of ions, and the design of strain and defects. E2DNMs possess unique characteristics, including a substantial surface area and controllable electrical, optical, and bioactive properties. These characteristics enable the development of sophisticated diagnostic platforms for real-time biosensors with exceptional sensitivity in detecting SARS-CoV-2. Integrating the Internet of Medical Things (IoMT) with these E2DNMs-based advanced diagnostics has led to the development of portable, real-time, scalable, more accurate, and cost-effective SARS-CoV-2 diagnostic platforms. These diagnostic platforms have the potential to revolutionize SARS-CoV-2 diagnosis by making it faster, easier, and more accessible to people worldwide, thus making them ideal for resource-limited settings. These advanced IoMT diagnostic platforms may help with combating SARS-CoV-2 as well as tracking and predicting the spread of future pandemics, ultimately saving lives and mitigating their impact on global health systems.

3D printed human organoids: High throughput system for drug screening and testing in current COVID-19 pandemic.

In the current pandemic, scenario the world is facing a huge shortage of effective drugs and other prophylactic medicine to treat patients which created havoc in several countries with poor resources. With limited demand and supply of effective drugs, researchers rushed to repurpose the existing approved drugs for the treatment of COVID-19. The process of drug screening and testing is very costly and requires several steps for validation and treatment efficacy evaluation ranging from in-vitro to in-vivo setups. After these steps, a clinical trial is mandatory for the evaluation of treatment efficacy and side effects in humans. These processes enhance the overall cost and sometimes the lead molecule show adverse effects in humans and the trial ends up in the final stages. Recently with the advent of three-dimensional (3D) organoid culture which mimics the human tissue exactly the process of drug screening and testing can be done in a faster and cost-effective manner. Further 3D organoids prepared from stems cells taken from individuals can be beneficial for personalized drug therapy which could save millions of lives. This review discussed approaches and techniques for the synthesis of 3D-printed human organoids for drug screening. The key findings of the usage of organoids for personalized medicine for the treatment of COVID-19 have been discussed. In the end, the key challenges for the wide applicability of human organoids for drug screening with prospects of future orientation have been included.

MXene-modified molecularly imprinted polymers as an artificial bio-recognition platform for efficient electrochemical sensing: progress and perspectives.

The development of efficient electrochemical sensors of exceptional features, molecularly imprinted polymers (MIPs), has been extensively utilized due to their great vitality as an alternative to bio-recognition elements. MIPs as an artificial bio-recognition element are getting significant attention due to their affordability, easy processability, and scaling-up capabilities. However, the challenge of longer stability and higher sensitivity associated with MIP-based sensing technology is still a remaining challenge. This can be addressed by modifying MIPs with electro-active nano-systems. Correspondingly, MXene is an emerging material of choice to make MIP-based sensing platforms more efficient and develop a bio-active-free sensing system. This review highlights state-of-the-art MXene-modified MIP electrochemical sensing platforms to overcome the associated limitations of pristine MIPs. As a proof-of-concept, the sensitive and selective detection of markers for health monitoring can be efficiently fulfilled by the high-performance MXene-MIP nanocomposite-based electrochemical sensor. Moreover, the challenges associated with this research area along with the potential solutions are also discussed. An attempt has been made to explore MXene-MIP nanocomposites as a next-generation sensing platform suitable for point-of-care testing (POCT) applications.

High throughput molecularly imprinted polymers based electrochemical nanosensors for point-of-care diagnostics of COVID-19.

The importance of early diagnosis of infectious disease has been revealed well by the COVID-19 pandemic. The current methods for testing SARS-CoV-2 mainly utilize biorecognition elements. The process of production of these biorecognition elements is not only tedious, time-consuming but also costly. The molecularly imprinted polymers recently have gained considerable attention as they are stable and also offer high selectivity and specificity than conventional labels. The present review discussed the MIPs-based electrochemical nano-sensors diagnostic of SARS-CoV-2.

Rapid detection of SARS-CoV-2 using graphene-based IoT integrated advanced electrochemical biosensor.

Unique characteristics like large surface area, excellent conductivity, functionality, ease of fabrication, etc., of graphene and its derivatives, have been extensively studied as potential candidates in healthcare applications. They have been utilized as a potential nanomaterial in biosensor fabrication for commercialized point-of-care (POC) devices. This review concisely provided innovative graphene and its derivative-based-IoT (Internet-of-Things) integrated electrochemical biosensor for accurate and advanced high-throughput testing of SARS-CoV-2 in POC setting.

Biosensor-based diagnostic approaches for various cellular biomarkers of breast cancer: A comprehensive review.

Breast cancer is the most commonly occurring cancer among women which leads to thousands of deaths worldwide. The chances of survival are more if the breast cancer is diagnosed at early stage. At present, mammography, magnetic resonance imaging, ultrasound and tissue biopsies are the main diagnostic techniques available for the detection of breast cancer. However, despite of offering promising results, requirement of expensive setup, skilled supervision, expert analysis, invasive procedure (biopsy) and low capacity of multiplexing are the main limitations of these diagnostic techniques. Due to high cost, these screening tests are out of reach of people belonging to low socioeconomic groups and this poses serious health burden to the society. Recently, biosensor-based diagnostic technology for early detection of various types of cancers and other non-oncological disorders have gained considerable attention because of their several advantageous features over existing diagnostic technologies such as high throughput, noninvasive nature, cost effectiveness, easy interpretable results and capacity for multiplexing. Further, biosensors can be designed for biomarkers which are confined to particular type of cancer. In this review, we have discussed about various genomic, transcriptomic, proteomic and metabolomic biomarkers associated with breast cancer, various biosensors-based diagnostic approaches designed for detection of specific biomarkers associated with breast cancer are also described. Further, this review throws insight on various biomarkers linked with breast cancer which can be effectively exploited to develop new diagnostic technology. The assessment of these biomarkers associated with BC using biosensors in large population are cost-effective, non-invasive and high throughput. They help in risk assessment of disease at very initial stage even in backward areas and also help to lower the disease burden of society and economic cost of treatment for a common man. This review would provide new avenues for the development of biosensor based diagnostic technology for the detection of biomarkers associated with breast cancer.

Fluorescence immunosensor for cardiac troponin T based on Förster resonance energy transfer (FRET) between carbon dot and MoS2 nano-couple.

In this study, we demonstrated a prompt and sensitive detection technique for cardiac troponin T (cTnT) in buffer and biological fluid (serum) using an NIR-active fluorescent anti-cTnT-labelled carbon dot (CD) and molybdenum disulfide (MoS2)-based nano-couple. Exfoliated MoS2 nanosheets strongly grasp the anti-cTnT-labelled CDs over their surface, and an excited-state non-radiative energy transfer mechanism takes place from CDs to MoS2, thereby quenching the upconversion fluorescence. The nonlinear and upward Stern-Volmer relationship is observed, which indicates a combined static and dynamic quenching. Static and time-resolved fluorescence measurements predict distance-dependent Förster resonance energy transfer (FRET) dynamics, which control the detection process. In the presence of cTnT, the energy transfer process gets hindered due to strong antibody/antigen (anti-cTnT/cTnT) interaction. The cTnT molecules affect the positions of the nano-couple and cause effective detachment of CDs from the MoS2 surface. This results hindrance in the energy transfer process with consequent restoration of upconversion intensity. A linear response is observed between the cTnT concentration and the restored fluorescence intensity in the concentration range of 0.1-50 ng mL-1 with a limit of detection of 0.12 ng mL-1 and a limit of quantification of 0.38 ng mL-1. Statistical analysis shows that the present assay possesses an accuracy of 101.4 ± 3.76 with a co-relation co-efficient of 0.99. Thus, CD/MoS2 provides a promising platform for the sensitive detection of cTnT.

Graphene oxide layer decorated gold nanoparticles based immunosensor for the detection of prostate cancer risk factor.

In this work, we report a novel electrochemical immunosensor based on gold nanoparticles deposited on the surface of graphene oxide layers and was used for immobilization of monoclonal anti-PSA antibody via EDC/NHS coupling method to detect prostate-specific antigen (PSA), a valuable biomarker for early detection of prostate cancer. To confirm the functionality of the antibody, we performed immunofluorescence staining using human prostate adenocarcinoma cells, LNCaP. Scanning Electron Microscopy (SEM), cyclic voltammetry, and other electrochemical techniques were used to characterize the resulting electrode surface. Unlike the previous research, this novel immunosensor functions very well with a low detection limit of 0.24 fgmL-1 at signal to noise ratio of 3; furthermore, it exhibits a significantly increased electron transfer and high sensitivity of 5.4 µA fgmL-1 with regression coefficient (R2 = 0.99) toward PSA. The immunosensor was verified for selective and accurate detection of PSA in human serum with recovery of 97.67%. Overall, data suggested that our developed biosensor holds great promise as a useful alternative diagnostic tool for the detection of different cancer biomarkers, in particular PSA present in biological samples.

Miniaturized MXene-based electrochemical biosensors for virus detection.

The timely control of infectious diseases can prevent the spread of infections and mitigate the significant socio-economic damage witnessed during recent pandemics. Diagnostic methods play a significant role in detecting highly contagious agents, such as viruses, to prevent further transmission. The emergence of advanced point-of-care techniques offers several advantages over conventional approaches for detecting infectious agents. These techniques are highly sensitive, rapid, can be miniaturized, and are cost-effective. Recently, MXene-based 2D nanocomposites have proven beneficial for fabricating electrochemical biosensors due to their suitable electrical, optical, and mechanical properties. This article covers electrochemical biosensors based on MXene nanocomposite for the detection of viruses, along with the associated challenges and future possibilities. Additionally, we highlight various conventional techniques for the detection of infectious agents, discussing their pros and cons. We delve into the challenges faced during the fabrication of MXene-based biosensors and explore future endeavors. It is anticipated that the information presented in this work will pave the way for the development of Point-of-Care (POC) devices capable of sensitive and selective virus detection, enhancing preparedness for ongoing and future pandemics.

Internet-of-things-integrated molecularly imprinted polymer-based electrochemical nano-sensors for pesticide detection in the environment and food products.

To ensure environmental and health safety, relevant pollutants such as pesticides must be screened thoroughly to set their permissible limit. Various approaches have been used to identify pesticides such as capillary electrophoresis, gas and liquid-liquid chromatography, high-performance liquid chromatography, and enzyme-linked immune-absorbent tests. However, these techniques have some drawbacks, including time-consuming difficult steps, expensive bulky equipment, expert personnel, and a lack of selectivity. Recent advances in the field of biosensing have introduced biosensors for the onsite detection of pesticides which offer several advantages including rapid, simple, selective, sensitive, low-cost operation, and on-site detection. With the advent of molecularly imprinted polymer which substituted the traditional biorecognition elements (BREs) such as enzymes and antibodies, biosensors' sensitivity, selectivity, and reproducibility enhanced many folds. Molecularly imprinted polymers (MIP) are artificial polymer molecules that resemble natural BREs. They are synthesized when functional monomers are polymerized in the presence of a target analyte. Owing to the advantages of MIP, in this paper, the development of MIP-based electrochemical biosensors for pesticide detection is reviewed critically. A brief introduction to pesticides and the use of MIPs-based electrochemical sensors for pesticide detection is presented along with pros and cons. Further, Internet of Things (IoT) integrated MIP-based nanosensors for pesticide detection and information distribution have been discussed. In the end, future perspectives and challenges while implementing MIP-based nanosensors for onsite pesticide recognition have eventually been highlighted.

Electrochemical Nanobiosensor of Ionic Liquid Functionalized MoO3-rGO for Sensitive Detection of Carcinoembryonic Antigen.

Early diagnosis of cancer can be achieved by detecting associated biomarkers before the appearance of symptoms. Herein, we have developed an electrochemical immunosensor of ionic liquid tailored to molybdenum trioxide-reduced graphene oxide (MoO3-rGO-IL) nanocomposite to detect carcinoembryonic antigen (CEA), a cancer biomarker. The MoO3-rGO-IL nanocomposite has been synthesized in situ via the hydrothermal method. The functionalization of 1-butyl-3-methylimidazolium tetrafluoroborate IL with MoO3-rGO synergistically improves the electrochemical and surface properties of the nanocomposite. The characterization studies revealed that the MoO3-rGO-IL nanocomposite is a highly appropriate material for the construction of immunosensors. The material exhibits exceptional electrical conductivity, surface properties, stability, and a large electrochemical effective surface area (13.77×10-2 cm2) making it ideal for fabricating immunosensors. The quantitative outcome showed that the developed immunosensor (BSA/anti-CEA/MoO3-rGO-IL/GCE) possesses excellent sensitivity, broad linearity from 25 fg mL-1 to 100 ng mL-1, and a low detection limit of 1.19 fg mL-1. Moreover, the remarkable selectivity, repeatability, and efficiency of detecting CEA in serum specimens demonstrated the feasibility of the immunosensor. Thus, the projected electrochemical immunosensor can potentially be utilized for the quantification of CEA in clinical specimens.

Epitope imprinted polymeric materials: application in electrochemical detection of disease biomarkers.

Epitope imprinting is a promising method for creating specialized recognition sites that resemble natural biorecognition elements. Epitope-imprinted materials have gained a lot of attention recently in a variety of fields, including bioanalysis, drug delivery, and clinical therapy. The vast applications of epitope imprinted polymers are due to the flexibility in choosing monomers, the simplicity in obtaining templates, specificity toward targets, and resistance to harsh environments along with being cost effective in nature. The "epitope imprinting technique," which uses only a tiny subunit of the target as the template during imprinting, offers a way around various drawbacks inherent to biomacromolecule systems i.e., traditional molecular imprinting techniques with regards to the large size of proteins, such as the size, complexity, accessibility, and conformational flexibility of the template. Electrochemical based sensors are proven to be promising tool for the quick, real-time monitoring of biomarkers. This review unravels epitope imprinting techniques, approaches, and strategies and highlights the applicability of these techniques for the electrochemical quantification of biomarkers for timely disease monitoring. In addition, some challenges are discussed along with future prospective developments.

MXene-based aptasensor for the detection of aflatoxin in food and agricultural products.

The detection of toxins that contaminate food needs highly sensitive and selective techniques to prevent substantial monitory loss. In this regard, various nanostructured material-enabled biosensors, have recently been developed to improve the detection of food toxins among them aflatoxin is the prevalent one. The biosensor-based detection of aflatoxin is quick, cheaper, and needs less skilled personnel, therefore overcoming the shortcomings of conventional techniques such as LC/MS-MS, HPLC, and ELISA assays. 2D MXenes manifest as an efficient material for biosensing due to their desirable biocompatibility, magnificent mechanical strength, easiness of surface functionalization, and tuneable optical and electronic features. Contrary to this, aptamers as biorecognition elements (BREs) possess high selectivity, sensitivity, and ease of synthesis when compared to conventional BREs. In this review, we explored the most cutting-edge aptamer-based MXene-enabled biosensing technologies for the detection of the most poisonous mycotoxins (i.e., Aflatoxins) in food and environmental matrices. The discussion begins with the synthesis processes and surface functionalization/modification of MXenes. Computational approaches for designing aptasensors and advanced data analysis based on artificial intelligence and machine learning with special emphasis over Internet-of-Thing integrated biosensing devices has been presented. Besides, the advantages of aptasensors over conventional methods along with their limitations have been briefed. Their benefits, drawbacks, and future potential are discussed concerning their analytical performance, utility, and on-site adaptability. Additionally, next-generation MXene-enabled biosensing technologies that provide end users with simple handling and improved sensitivity and selectivity have been emphasized. Owing to massive applicability, economic/commercial potential of MXene in current and future perspective have been highlighted. Finally, the existing difficulties are scrutinized and a roadmap for developing sophisticated biosensing technologies to detect toxins in various samples in the future is projected.

Synergistically functionalized molybdenum disulfide-reduced graphene oxide nanohybrid based ultrasensitive electrochemical immunosensor for real sample analysis of COVID-19.

Herein, we have proposed a straightforward and label-free electrochemical immunosensing strategy supported on a glassy carbon electrode (GCE) modified with a biocompatible and conducting biopolymer functionalized molybdenum disulfide-reduced graphene oxide (CS-MoS2/rGO) nanohybrid to investigate the SARS-CoV-2 virus. CS-MoS2/rGO nanohybrid-based immunosensor employs recombinant SARS-CoV-2 Spike RBD protein (rSP) that specifically identifies antibodies against the SARS-CoV-2 virus via differential pulse voltammetry (DPV). The antigen-antibody interaction diminishes the current responses of the immunosensor. The obtained results indicate that the fabricated immunosensor is extraordinarily capable of highly sensitive and specific detection of the corresponding SARS-CoV-2 antibodies with a LOD of 2.38 zg mL-1 in phosphate buffer saline (PBS) samples over a broad linear range between 10 zg mL-1-100 ng mL-1. In addition, the proposed immunosensor can detect attomolar concentrations in spiked human serum samples. The performance of this immunosensor is assessed using actual serum samples from COVID-19-infected patients. The proposed immunosensor can accurately and substantially differentiate between (+) positive and (-) negative samples. As a result, the nanohybrid can provide insight into the conception of Point-of-Care Testing (POCT) platforms for cutting-edge infectious disease diagnostic methods.

Multifunctional GQDs for receptor targeting, drug delivery, and bioimaging in pancreatic cancer.

Pancreatic cancer is a devastating disease with a low survival rate and limited treatment options. Graphene quantum dots (GQDs) have recently become popular as a promising platform for cancer diagnosis and treatment due to their exceptional physicochemical properties, such as biocompatibility, stability, and fluorescence. This review discusses the potential of multifunctional GQDs as a platform for receptor targeting, drug delivery, and bioimaging in pancreatic cancer. The current studies emphasized the ability of GQDs to selectively target pancreatic cancer cells by overexpressing binding receptors on the cell surface. Additionally, this review discussed the uses of GQDs as drug delivery vehicles for the controlled and targeted release of therapeutics for pancreatic cancer cells. Finally, the potential of GQDs as imaging agents for pancreatic cancer detection and monitoring has been discussed. Overall, multifunctional GQDs showed great promise as a versatile platform for the diagnosis and treatment of pancreatic cancer. Further investigation of multifunctional GQDs in terms of their potential and optimization in the context of pancreatic cancer therapy is needed.

COVID-19 associated thyroid dysfunction and other comorbidities and its management using phytochemical-based therapeutics: a natural way.

The present severe acute respiratory syndrome-2 (SARS-CoV-2) mediated Coronavirus pandemic (COVID-19) and post-COVID-19 complications affect human life drastically. Patients who have been cured of COVID-19 infection are now experiencing post-COVID-19 associated comorbidities, which have increased mortality rates. The SARS-CoV-2 infection distresses the lungs, kidneys, gastrointestinal tract, and various endocrine glands, including the thyroid. The emergence of variants which includes Omicron (B.1.1.529) and its lineages threaten the world severely. Among different therapeutic approaches, phytochemical-based therapeutics are not only cost-effective but also have lesser side effects. Recently a plethora of studies have shown the therapeutic efficacy of various phytochemicals for the treatment of COVID-19. Besides this, various phytochemicals have been found efficacious in treating several inflammatory diseases, including thyroid-related anomalies. The method of the phytochemical formulation is quick and facile and the raw materials for such herbal preparations are approved worldwide for human use against certain disease conditions. Owing to the advantages of phytochemicals, this review primarily discusses the COVID-19-related thyroid dysfunction and the role of key phytochemicals to deal with thyroid anomaly and post-COVID-19 complications. Further, this review shed light on the mechanism via which COVID-19 and its related complication affect organ function of the body, along with the mechanistic insight into the way by which phytochemicals could help to cure post-COVID-19 complications in thyroid patients. Considering the advantages offered by phytochemicals as a safer and cost-effective medication they can be potentially used to combat COVID-19-associated comorbidities.

Cryopreservation: A Comprehensive Overview, Challenges, and Future Perspectives.

Cryopreservation is the most prevalent method of long-term cell preservation. Effective cell cryopreservation depends on freezing, adequate storage, and correct thawing techniques. Recent advances in cryopreservation techniques minimize the cellular damage which occurs while processing samples. This article focuses on the fundamentals of cryopreservation techniques and how they can be implemented in a variety of clinical settings. The article presents a brief description of each of the standard cryopreservation procedures, such as slow freezing and vitrification. Alongside that, the membrane permeating and nonpermeating cryoprotectants are briefly discussed, along with current advancements in the field of cryopreservation and variables influencing the cryopreservation process. The diminution of cryoinjury incurred by the cell via the resuscitation process will also be highlighted. In the end application of cryopreservation techniques in many fields, with a special emphasis on stem cell preservation techniques and current advancements presented. Furthermore, the challenges while implementing cryopreservation and the futuristic scope of the fields are illustrated herein. The content of this review sheds light on various ways to enhance the output of the cell preservation process and minimize cryoinjury while improving cell revival.

Green Synthesis of CdS and CdS/rGO Nanocomposites: Evaluation of Electrochemical, Antimicrobial, and Photocatalytic Properties.

The green approach has been employed for the synthesis of various types of nanomaterials including metal nanoparticles, metal oxides, and carbon-based nanomaterials. These processes involve natural sources that contain bioactive compounds that act as reducing, stabilizing, and capping agents for the formation and stabilization of nanomaterials. This study reports the green synthesis of CdS and CdS/rGO nanocomposites using Lactobacillus bacteria. The UV-visible spectrophotometer, field emission scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, Raman spectroscopy, and Fourier transform infrared spectroscopy spectra confirm the synthesis of the nanocomposite. The electrochemical characterization using cyclic voltammetry, differential pulse voltammetry, and EIS revealed that the CdS/rGO nanocomposites showed a higher electron transfer rate compared with CdS nanoparticles, indicating the potential of the nanocomposites for biosensing applications. The zone of inhibition revealed significant antimicrobial activity against Escherichia coli and Staphylococcus aureus for both CdS nanoparticles and CdS/rGO nanocomposites. Additionally, CdS/rGO nanoparticles exhibited high photocatalytic activity for the degradation of methylene blue dye. Overall, this study demonstrates that the synthesized CdS and CdS/rGO nanocomposites have good electrochemical properties, photocatalytic, and antimicrobial activity and, therefore, can be employed for various applications such as biosensing, photocatalysis, and antimicrobial activity.

Internet-of-medical-things integrated point-of-care biosensing devices for infectious diseases: Toward better preparedness for futuristic pandemics.

Microbial pathogens have threatened the world due to their pathogenicity and ability to spread in communities. The conventional laboratory-based diagnostics of microbes such as bacteria and viruses need bulky expensive experimental instruments and skilled personnel which limits their usage in resource-limited settings. The biosensors-based point-of-care (POC) diagnostics have shown huge potential to detect microbial pathogens in a faster, cost-effective, and user-friendly manner. The use of various transducers such as electrochemical and optical along with microfluidic integrated biosensors further enhances the sensitivity and selectivity of detection. Additionally, microfluidic-based biosensors offer the advantages of multiplexed detection of analyte and the ability to deal with nanoliters volume of fluid in an integrated portable platform. In the present review, we discussed the design and fabrication of POCT devices for the detection of microbial pathogens which include bacteria, viruses, fungi, and parasites. The electrochemical techniques and current advances in this field in terms of integrated electrochemical platforms that include mainly microfluidic- based approaches and smartphone and Internet-of-things (IoT) and Internet-of-Medical-Things (IoMT) integrated systems have been highlighted. Further, the availability of commercial biosensors for the detection of microbial pathogens will be briefed. In the end, the challenges while fabrication of POC biosensors and expected future advances in the field of biosensing have been discussed. The integrated biosensor-based platforms with the IoT/IoMT usually collect the data to track the community spread of infectious diseases which would be beneficial in terms of better preparedness for current and futuristic pandemics and is expected to prevent social and economic losses.

Electrochemical Immunosensor for Early Detection of ß-Amyloid Alzheimer's Disease Biomarker Based on Aligned Carbon Nanotubes Gold Nanocomposites.

Beta-amyloid (ßA) peptides accompanying the physiological change in brain induce Alzheimer's disease. In this work, a highly sensitive electrochemical (EC) immunosensor platform has been developed for the quantitative detection of ßA peptides, using the gold nanoparticle functionalized chitosan-aligned carbon nanotube (CS-aCNT-Au) nanocomposites on glassy carbon electrodes (GCE). The immunosensor has been fabricated by immobilization of the anti-ßA antibody upon CS-aCNT-Au/GCE. In the CS-aCNT nanocomposite, CS has high biocompatibility. Hydroxy and amine functionalities favor the antibody immobilization and prevent the leaching of nanocomposites of the modified electrode due to the adhesive environment. Moreover, aCNT offers high conductivity, stability, and a large surface area (the calculated effective surface area of the CS-aCNT/GCE is 8.594 × 10-2 cm2). However, the incorporation of AuNPs further enhances the conductivity of the CS-aCNT-Au nanocomposite based on differential pulse voltammetry (DPV) results, and also improves the effective surface area (9.735 × 10-2 cm2). The surface morphology and electrochemical studies of the nanocomposite, as well as its modifications by the anti-ßA antibody and BSA, were carried out through field emission scanning electron microscope (FESEM), cyclic voltammetry (CV), and DPV. The quantitative immunosensing of the ßA in phosphate-buffered saline (PBS) solution is accomplished via DPV, which reveals that the immunosensor has a high sensitivity of 157.60 µA pg-1 mL cm-2 and a broad detection range of 10.0 pg mL-1-100.0 µg mL-1, with a limit of detection (LOD) of 0.87 pg mL-1. Subsequently, we detected the spiked ßA in diluted serum with a linear detection range of 10.0 pg mL-1-1.0 ng mL-1 and LOD of 0.95 pg mL-1. Moreover, a selectivity study exhibited a high affinity of immunosensors towards ßA. Thus, we propose that this highly efficient immunosensor can potentially be applied for the point-of-care (POC) sensing of ßA in clinical samples.