A sample-to-answer electrochemical biosensor system for biomarker detection

Label-Free detection of Poly-Cystic Ovarian Syndrome using a highly conductive 2-D rGO/MoS2/PANI nanocomposite based immunosensor

Polycystic ovarian syndrome (PCOS) is an endocrinal disorder characterized by multiple tiny cysts, amenorrhea, dysmenorrhea, hirsutism, and infertility. The current diagnostic tools comprise of expensive, time-consuming ultrasonography to serological test, which have low patient compliance. To address these limitations, we have developed a highly sensitive, cost effective and ultrafast immunosensor for the diagnosis of PCOS. Herein, we have fabricated a 2-D electro conductive composites of reduced Graphene oxide (rGO), Molybdenum disulfide (MoS2), and Polyaniline (PANI) as electrode material. Furthermore, for detecting an early and non-cyclic biomarker of PCOS, i.e. anti-Mullerian hormone (AMH). We utilize the specific antigen-antibody mechanism, in which monoclonal Anti-AMH antibodies were covalently immobilized using EDC-NHS chemistry on electrode. The developed biosensor was physicochemical and electrochemically characterized to demonstrate its efficiency. Further we have investigated the biosensor's performance with Cyclic Voltammetry, Differential Pulse Voltammetry, and Electrochemical Impedance Spectroscopy. We have validated that under the optimized condition the immunosensor exhibits higher sensitivity with a LOD of ∼ 2.0 ng/mL with a linear range up to 100 ng/mL. Furthermore, this immunosensor works efficiently with a lower sample volume (>5 μL), which provides a sensitive, reproducible, low-cost, rapid analysis to detect AMH level in PCOS diagnosis.

Extended Review Concerning the Integration of Electrochemical Biosensors into Modern IoT and Wearable Devices

Electrochemical biosensors include a recognition component and an electronic transducer, which detect the body fluids with a high degree of accuracy. More importantly, they generate timely readings of the related physiological parameters, and they are suitable for integration into portable, wearable and implantable devices that are significant relative to point-of-care diagnostics scenarios. As an example, the personal glucose meter fundamentally improves the management of diabetes in the comfort of the patients' homes. This review paper analyzes the principles of electrochemical biosensing and the structural features of electrochemical biosensors relative to the implementation of health monitoring and disease diagnostics strategies. The analysis particularly considers the integration of the biosensors into wearable, portable, and implantable systems. The fundamental aim of this paper is to present and critically evaluate the identified significant developments in the scope of electrochemical biosensing for preventive and customized point-of-care diagnostic devices. The paper also approaches the most important engineering challenges that should be addressed in order to improve the sensing accuracy, and enable multiplexing and one-step processes, which mediate the integration of electrochemical biosensing devices into digital healthcare scenarios.

Integrated Microwell Array-Based Microfluidic Chip with a Hand-Held Smartphone-Controlled Device for Nucleic Acid Detection

In this study, we designed a highly integrated microfluidic chip for nucleic acid extraction, amplification, and detection. Magnetic beads, which are used to capture nucleic acids on the chip, are trapped in the microwell arrays in a one-well-one-bead manner after local surface modification of the inner faces of the microwells. On-chip liquid introduction, delivery, and mixing are all carried out manually with one syringe and no other equipment. A hand-held device with precise temperature control and high-quality imaging is developed, which is only 2.3 cubic decimeters in volume and 1.2 kg in weight. Via the use of the Internet for wireless communication, the experiment and data analysis after inserting the chip into the device can be conducted by a smartphone anywhere there is an Internet connection. We carried out reverse transcription loop-mediated isothermal amplification (RT-LAMP) on the chip with the hand-held device. SARS-CoV-2 pseudoviruses are extracted, reverse transcribed, amplified, and detected on the chip with the hand-held device with satisfactory results. Thus, a highly integrated, easy-to-operate, and rapid nucleic acid detection microfluidic chip with a hand-held smartphone-controlled device is proposed, and this new platform for nucleic acid detection shows great potential for mobile point-of-care testing (POCT).

Rapid, low-cost fabrication of electronic microfluidics via inkjet-printing and xurography (MINX)

Microfluidics has shown great promise for point-of-care assays due to unique chemical and physical advantages that occur at the micron scale. Furthermore, integration of electrodes into microfluidic systems provides additional capabilities for assay operation and electronic readout. However, while these systems are abundant in biological and biomedical research settings, translation of microfluidic devices with embedded electrodes are limited. In part, this is due to the reliance on expensive, inaccessible, and laborious microfabrication techniques. Although innovative prior work has simplified microfluidic fabrication or inexpensively patterned electrodes, low-cost, accessible, and robust methods to incorporate all these elements are lacking. Here, we present MINX, a low-cost <1 USD and rapid (∼minutes) fabrication technique to manufacture microfluidic device with embedded electrodes. We characterize the structures created using MINX, and then demonstrate the utility of the approach by using MINX to implement an electrochemical bead-based biomarker detection assay. We show that the MINX technique enables the scalable, inexpensive fabrication of microfluidic devices with electronic sensors using widely accessible desktop machines and low-cost materials.

DNA Sensing Platforms: Novel Insights into Molecular Grafting Using Low Perturbative AFM Imaging

By using AFM as a nanografting tool, we grafted micrometer-sized DNA platforms into inert alkanethiol SAMs. Tuning the grafting conditions (surface density of grafting lines and scan rate) allowed us to tailor the molecular density of the DNA platforms. Following the nanografting process, AFM was operated in the low perturbative Quantitative Imaging (QI) mode. The analysis of QI AFM images showed the coexistence of molecular domains of different heights, and thus different densities, within the grafted areas, which were not previously reported using contact AFM imaging. Thinner domains corresponded to low-density DNA regions characterized by loosely packed, randomly oriented DNA strands, while thicker domains corresponded to regions with more densely grafted DNA. Grafting with densely spaced and slow scans increased the size of the high-density domains, resulting in an overall increase in patch height. The structure of the grafted DNA was compared to self-assembled DNA, which was assessed through nanoshaving experiments. Exposing the DNA patches to the target sequence produced an increase in the patch height, indicating that hybridization was accomplished. The relative height increase of the DNA patches upon hybridization was higher in the case of lower density patches due to hybridization leading to a larger molecular reorganization. Low density DNA patches were therefore the most suitable for targeting oligonucleotide sequences.

Affinity-based electrochemical sensors for biomolecular detection in whole blood

The detection and/or quantification of biomarkers in blood is important for the early detection, diagnosis, and treatment of a variety of diseases and medical conditions. Among the different types of sensors for detecting molecular biomarkers, such as proteins, nucleic acids, and small-molecule drugs, affinity-based electrochemical sensors offer the advantages of high analytical sensitivity and specificity, fast detection times, simple operation, and portability. However, biomolecular detection in whole blood is challenging due to its highly complex matrix, necessitating sample purification (i.e., centrifugation), which involves the use of bulky, expensive equipment and tedious sample-handling procedures. To address these challenges, various strategies have been employed, such as purifying the blood sample directly on the sensor, employing micro-/nanoparticles to enhance the detection signal, and coating the electrode surface with blocking agents to reduce nonspecific binding, to improve the analytical performance of affinity-based electrochemical sensors without requiring sample pre-processing steps or laboratory equipment. In this article, we present an overview of affinity-based electrochemical sensor technologies that employ these strategies for biomolecular detection in whole blood.

Device integration of electrochemical biosensors

Electrochemical biosensors incorporate a recognition element and an electronic transducer for the highly sensitive detection of analytes in body fluids. Importantly, they can provide rapid readouts and they can be integrated into portable, wearable and implantable devices for point-of-care diagnostics; for example, the personal glucose meter enables at-home assessment of blood glucose levels, greatly improving the management of diabetes. In this Review, we discuss the principles of electrochemical biosensing and the design of electrochemical biosensor devices for health monitoring and disease diagnostics, with a particular focus on device integration into wearable, portable and implantable systems. Finally, we outline the key engineering challenges that need to be addressed to improve sensing accuracy, enable multiplexing and one-step processes, and integrate electrochemical biosensing devices in digital health-care pathways.

Recent Trends in Metal Nanoparticles Decorated 2D Materials for Electrochemical Biomarker Detection

Technological advancements in the healthcare sector have pushed for improved sensors and devices for disease diagnosis and treatment. Recently, with the discovery of numerous biomarkers for various specific physiological conditions, early disease screening has become a possibility. Biomarkers are the body's early warning systems, which are indicators of a biological state that provides a standardized and precise way of evaluating the progression of disease or infection. Owing to the extremely low concentrations of various biomarkers in bodily fluids, signal amplification strategies have become crucial for the detection of biomarkers. Metal nanoparticles are commonly applied on 2D platforms to anchor antibodies and enhance the signals for electrochemical biomarker detection. In this context, this review will discuss the recent trends and advances in metal nanoparticle decorated 2D materials for electrochemical biomarker detection. The prospects, advantages, and limitations of this strategy also will be discussed in the concluding section of this review.