Using low-cost disposable immunosensor based on flexible PET screen-printed electrode modified with carbon black and gold nanoparticles for sensitive detection of SARS-CoV-2

Tuning surface morphology of AuNPs film via thiourea as a stable SERS platform for methylene blue

Gold nanoparticles (AuNPs) have been extensively utilized in various fields such as sensors, life sciences, and catalysis. In this study, AuNPs were synthesized using a reduction method and subsequently treated with thiourea in an ethanol-water environment to prepare AuNPs film using a centrifugal deposition method for first time, resulting in the aggregation of the initial small-sized AuNPs into larger microsphere-like structures. The addition of thiourea facilitated the interconnection between AuNPs, ultimately leading to the formation of large stable gold microspheres. The sheet resistance of the AuNP films transitioned from being non-conductive to exhibiting a sheet resistance of 42.6 Ω/sq following thiourea treatment. The transformation from a flat surface to tightly connected particles resembling microspheres was observed from SEM images. The thiourea treatment not only altered the morphological characteristic of the AuNPs films but also significantly increased the number of scattering sites on their surface, leading to a substantial enhancement in the Raman scattering effect for methylene blue. This structural configuration also improved the electronic conduction and stability of the treated AuNPs films. Consequently, these findings suggest that AuNPs have promising application prospects in surface-enhanced Raman scatting (SERS), as well as in flexible electronics, catalysis, adsorption, and energy fields.

Electroanalysis of Statin Drugs: A Review on the Electrochemical Sensor Architectures Ranging from Classical to Modern Systems

An overview of the latest advances in the design of electrochemical sensor architectures dedicated to the determination of drugs from the statin class is presented in this review. Statins are drugs widely consumed for cholesterol control, and their determination in different matrices through the application of electroanalysis is growing considering advantages such as operational simplicity, lower cost and ease of sample preparation. Within the context of statins, electrochemical sensor architectures can be subdivided into conventional/classical electrodes such as glassy carbon electrodes, carbon paste electrodes, pencil graphite electrodes, boron-doped diamond electrodes and metallic electrodes, and more modern electrode systems, including the screen-printed electrodes and 3D-printed electrodes. Thus, different aspects related to the preparation of these electrochemical sensors and analytical performance are presented, also reflecting advances in terms of designs of new architectures and possible improvements not previously reviewed. Analyzed samples, advantages and disadvantages of different implemented sensor's modification strategies and perspectives for the electroanalysis of statins are also included throughout the work.

Surface-Enhanced Raman Scattering Combined with Machine Learning for Rapid and Sensitive Detection of Anti-SARS-CoV-2 IgG

This work reports an efficient method to detect SARS-CoV-2 antibodies in blood samples based on SERS combined with a machine learning tool. For this purpose, gold nanoparticles directly conjugated with spike protein were used in human blood samples to identify anti-SARS-CoV-2 antibodies. The comprehensive database utilized Raman spectra from all 594 blood serum samples. Machine learning investigations were carried out using the Scikit-Learn library and were implemented in Python, and the characteristics of Raman spectra of positive and negative SARS-CoV-2 samples were extracted using the Uniform Manifold Approximation and Projection (UMAP) technique. The machine learning models used were k-Nearest Neighbors (kNN), Support Vector Machine (SVM), Decision Trees (DTs), logistic regression (LR), and Light Gradient Boosting Machine (LightGBM). The kNN model led to a sensitivity of 0.943, specificity of 0.9275, and accuracy of 0.9377. This study showed that combining Raman spectroscopy and a machine algorithm can be an effective diagnostic method. Furthermore, we highlighted the advantages and disadvantages of each algorithm, providing valuable information for future research.

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

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

Cutting-edge biorecognition strategies to boost the detection performance of COVID-19 electrochemical biosensors: A review

Electrochemical biosensors are known for their high sensitivity, selectivity, and low cost. Recently, they have gained significant attention and became particularly important as promising tools for the detection of COVID-19 biomarkers, since they offer a rapid and accurate means of diagnosis. Biorecognition strategies are a crucial component of electrochemical biosensors and determine their specificity and sensitivity based on the interaction of biological molecules, such as antibodies, enzymes, and DNA, with target analytes (e.g., viral particles, proteins and genetic material) to create a measurable signal. Different biorecognition strategies have been developed to enhance the performance of electrochemical biosensors, including direct, competitive, and sandwich binding, alongside nucleic acid hybridization mechanisms and gene editing systems. In this review article, we present the different strategies used in electrochemical biosensors to target SARS-CoV-2 and other COVID-19 biomarkers, as well as explore the advantages and disadvantages of each strategy and highlight recent progress in this field. Additionally, we discuss the challenges associated with developing electrochemical biosensors for clinical COVID-19 diagnosis and their widespread commercialization.

Hierarchical Nanobiosensors at the End of the SARS-CoV-2 Pandemic

Nanostructures have played a key role in the development of different techniques to attack severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Some applications include masks, vaccines, and biosensors. The latter are of great interest for detecting diseases since some of their features allowed us to find specific markers in secretion samples such as saliva, blood, and even tears. Herein, we highlight how hierarchical nanoparticles integrated into two or more low-dimensional materials present outstanding advantages that are attractive for photonic biosensing using their nanoscale functions. The potential of nanohybrids with their superlative mechanical characteristics together with their optical and optoelectronic properties is discussed. The progress in the scientific research focused on using nanoparticles for biosensing a variety of viruses has become a medical milestone in recent years, and has laid the groundwork for future disease treatments. This perspective analyzes the crucial information about the use of hierarchical nanostructures in biosensing for the prevention, treatment, and mitigation of SARS-CoV-2 effects.

Detection of antibodies against SARS-CoV-2 Spike protein by screen-printed carbon electrodes modified by colloidal gold nanoparticles

In this work, electrochemical bioanalytical systems for the determination of antibodies against the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Spike protein (anti-rS) is reported. Environmentally friendly chemicals were applied in the synthesis of gold nanoparticles (AuNPs). The AuNPs were integrated onto the screen-printed carbon electrodes (SPE), and the biological recognition part was based on recombinant SARS-CoV-2 Spike protein (rS), which during the immobilization was cross-linked by glutaraldehyde. Immobilized rS protein based biological recognition part enabled selective recognition of anti-rS antibodies. The current flux of AuNPs reduction (at +200 mV) in a pure phosphate buffer (PB) was employed as the transduction signal. It has been reported that the formation of anti-rS layers on the surface of AuNPs delays the electrode response time (ts), tracked at the current flux density values of 80 μA cm-2. Using the AuNP-modified SPE, we demonstrated a rapid anti-rS detection within a detection limit of 2 ng mL-1 (0.125 binding antibody units mL-1, 17 pM). This system can be applied to track the response of immune system towards SARS-CoV-2 infection and monitoring of Coronavirus Disease 2019 (COVID-19).

Recent Advances in Metallic Nanostructures-assisted Biosensors for Medical Diagnosis and Therapy

The field of nanotechnology has witnessed remarkable progress in recent years, particularly in its application to medical diagnosis and therapy. Metallic nanostructures-assisted biosensors have emerged as a powerful and versatile platform, offering unprecedented opportunities for sensitive, specific, and minimally invasive diagnostic techniques, as well as innovative therapeutic interventions. These biosensors exploit the molecular interactions occurring between biomolecules, such as antibodies, enzymes, aptamers, or nucleic acids, and metallic surfaces to induce observable alterations in multiple physical attributes, encompassing electrical, optical, colorimetric, and electrochemical signals. These interactions yield measurable data concerning the existence and concentration of particular biomolecules. The inherent characteristics of metal nanostructures, such as conductivity, plasmon resonance, and catalytic activity, serve to amplify both sensitivity and specificity in these biosensors. This review provides an in-depth exploration of the latest advancements in metallic nanostructures-assisted biosensors, highlighting their transformative impact on medical science and envisioning their potential in shaping the future of personalized healthcare.

Disposable and eco-friendly electrochemical immunosensor for rapid detection of SARS-CoV-2

This study describes the development of a simple, disposable, and eco-friendly electrochemical immunosensor for rapid detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Electrochemical devices were manufactured by stencil-printing using low-cost materials such as polyester sheets, graphite flakes, and natural resin. The immunosensor comprises gold nanoparticles stabilized with cysteamine, glutaraldehyde, anti-SARS-CoV-2 S protein monoclonal antibody (Ab1) as the biological receptor, and bovine serum albumin as a protective layer. The COVID-19 diagnostic was based on rapid square wave voltammetry measurements (15 min) using [Fe(CN)6]3-/4- as a redox probe. The method presented a linear response in the concentration range from 250 pg mL-1 to 20 μg mL-1 S protein, with a limit of detection of 36.3 pg mL-1. The proposed immunosensor was stable for up to two weeks when stored at 4 °C and it demonstrated excellent clinical performance in diagnosing COVID-19 when applied to a panel of 44 undiluted swab samples collected from symptomatic patients. In comparison with results obtained through the quantitative reverse transcription polymerase chain reaction method, the proposed immunosensor offered 100 % accuracy, thus emerging as a powerful alternative candidate for routine and decentralized testing, which can be helpful in controlling the COVID-19 outbreak.

Electrochemical determination of Roxarsone using preconcentration-based signal amplification on modified screen-printed electrode

A lab-made screen-printed electrode based on poly(ethylene terephthalate) (PET) substrate modified with a hybrid film containing gold nanoparticles-decorated graphene (AuNPs-GRA/PET-SPE) was employed for the voltammetric determination of Roxarsone (ROX) in chicken purge and river water samples. The electrode exhibited an increased electroactive area and enhanced charge transfer due to the nanostructured matrix. The electrochemical determination involved a preconcentration approach with a reduction step of ROX at a constant potential of -0.6 V, followed by voltammetric sweep towards the oxidation of the adsorbed hydroxylamine at 0.32 V. The methodology achieved a limit of detection of 60 nM and 97 nM for ROX in diluted river water and chicken purge samples, respectively. This effective methodology offers a promising tool for monitoring ROX levels in environmental and food samples.

Detection of SARS-CoV-2 in Environment: Current Surveillance and Effective Data Management of COVID-19

Since diagnostic laboratories handle large COVID-19 samples, researchers have established laboratory-based assays and developed biosensor prototypes. Both share the same purpose; to ascertain the occurrence of air and surface contaminations by the SARS-CoV-2 virus. However, the biosensors further utilize internet-of-things (IoT) technology to monitor COVID-19 virus contamination, specifically in the diagnostic laboratory setting. The IoT-capable biosensors have great potential to monitor for possible virus contamination. Numerous studies have been done on COVID-19 virus air and surface contamination in the hospital setting. Through reviews, there are abundant reports on the viral transmission of SARS-CoV-2 through droplet infections, person-to-person close contact and fecal-oral transmission. However, studies on environmental conditions need to be better reported. Therefore, this review covers the detection of SARS-CoV-2 in airborne and wastewater samples using biosensors with comprehensive studies in methods and techniques of sampling and sensing (2020 until 2023). Furthermore, the review exposes sensing cases in public health settings. Then, the integration of data management together with biosensors is well explained. Last, the review ended with challenges to having a practical COVID-19 biosensor applied for environmental surveillance samples.