Development of a Microfluidic Device for Exosome Isolation in Point-of-Care Settings.

Exosomes have gained recognition in cancer diagnostics and therapeutics. However, most exosome isolation methods are time-consuming, costly, and require bulky equipment, rendering them unsuitable for point-of-care (POC) settings. Microfluidics can be the key to solving these challenges. Here, we present a double filtration microfluidic device that can rapidly isolate exosomes via size-exclusion principles in POC settings. The device can efficiently isolate exosomes from 50-100 µL of plasma within 50 min. The device was compared against an already established exosome isolation method, polyethylene glycol (PEG)-based precipitation. The findings showed that both methods yield comparable exosome sizes and purity; however, exosomes isolated from the device exhibited an earlier miRNA detection compared to exosomes obtained from the PEG-based isolation. A comparative analysis of exosomes collected from membrane filters with 15 nm and 30 nm pore sizes showed a similarity in exosome size and miRNA detection, with significantly increased sample purity. Finally, TEM images were taken to analyze how the developed devices and PEG-based isolation alter exosome morphology and to analyze exosome sizes. This developed microfluidic device is cost-efficient and time-efficient. Thus, it is ideal for use in low-resourced and POC settings to aid in cancer and disease diagnostics and therapeutics.

Electrochemical Impedance Spectroscopy-Based Sensing of Biofilms: A Comprehensive Review.

Biofilms are complex communities of microorganisms that can form on various surfaces, including medical devices, industrial equipment, and natural environments. The presence of biofilms can lead to a range of problems, including infections, reduced efficiency and failure of equipment, biofouling or spoilage, and environmental damage. As a result, there is a growing need for tools to measure and monitor levels of biofilms in various biomedical, pharmaceutical, and food processing settings. In recent years, electrochemical impedance sensing has emerged as a promising approach for real-time, non-destructive, and rapid monitoring of biofilms. This article sheds light on electrochemical sensing for measuring biofilms, including its high sensitivity, non-destructive nature, versatility, low cost, and real-time monitoring capabilities. We also discussed some electrochemical sensing applications for studying biofilms in medical, environmental, and industrial settings. This article also presents future perspectives for research that would lead to the creation of reliable, quick, easy-to-use biosensors mounted on unmanned aerial vehicles (UAVs), and unmanned ground vehicles (UGVs), utilizing artificial intelligence-based terminologies to detect biofilms.

An origami-based technique for simple, effective and inexpensive fabrication of highly aligned far-field electrospun fibers.

Fabrication of highly aligned fibers by far-field electrospinning is a challenging task to accomplish. Multiple studies present advances in the alignment of electrospun fibers which involve modification of the conventional electrospinning setup with complex additions, multi-phased fabrication, and expensive components. This study presents a new collector design with an origami structure to produce highly-aligned far-field electrospun fibers. The origami collector mounts on the rotating drum and can be easily attached and removed for each round of fiber fabrication. This simple, effective, and inexpensive technique yields high-quality ultra-aligned fibers while the setup remains intact for other fabrication types. The electrospun poly(ɛ-caprolactone) (PCL) fibers were assessed by scanning electron microscope (SEM), fiber diameter distribution, water contact angle (WCA), Fast Fourier Transform analysis (FFT), surface plot profile, and pixel intensity plots. We thoroughly explored the impact of influential parameters, including polymer concentration, injection rate, collector rotation speed, distance from the collector to the tip, and needle gauge number on fibers' quality and alignment. Moreover, we employed machine learning algorithms to predict the outcomes and classify the high-quality fibers instead of low-quality productions.

A Meta-Analysis of Wearable Contact Lenses for Medical Applications: Role of Electrospun Fiber for Drug Delivery.

In recent years, wearable contact lenses for medical applications have attracted significant attention, as they enable continuous real-time recording of physiological information via active and noninvasive measurements. These devices play a vital role in continuous monitoring of intraocular pressure (IOP), noninvasive glucose monitoring in diabetes patients, drug delivery for the treatment of ocular illnesses, and colorblindness treatment. In specific, this class of medical devices is rapidly advancing in the area of drug loading and ocular drug release through incorporation of electrospun fibers. The electrospun fiber matrices offer a high surface area, controlled morphology, wettability, biocompatibility, and tunable porosity, which are highly desirable for controlled drug release. This article provides an overview of the advances of contact lens devices in medical applications with a focus on four main applications of these soft wearable devices: (i) IOP measurement and monitoring, (ii) glucose detection, (iii) ocular drug delivery, and (iv) colorblindness treatment. For each category and application, significant challenges and shortcomings of the current devices are thoroughly discussed, and new areas of opportunity are suggested. We also emphasize the role of electrospun fibers, their fabrication methods along with their characteristics, and the integration of diverse fiber types within the structure of the wearable contact lenses for efficient drug loading, in addition to controlled and sustained drug release. This review article also presents relevant statistics on the evolution of medical contact lenses over the last two decades, their strengths, and the future avenues for making the essential transition from clinical trials to real-world applications.

Nano-engineered screen-printed electrodes: A dynamic tool for detection of viruses.

There is a growing interest in the development of portable, cost-effective, and easy-to-use biosensors for the rapid detection of diseases caused by infectious viruses: COVID-19 pandemic has highlighted the central role of diagnostics in response to global outbreaks. Among all the existing technologies, screen-printed electrodes (SPEs) represent a valuable technology for the detection of various viral pathogens. During the last five years, various nanomaterials have been utilized to modify SPEs to achieve convincing effects on the analytical performances of portable SPE-based diagnostics. Herein we would like to provide the readers a comprehensive investigation about the recent combination of SPEs and various nanomaterials for detecting viral pathogens. Manufacturing methods and features advances are critically discussed in the context of early-stage detection of diseases caused by HIV-1, HBV, HCV, Zika, Dengue, and Sars-CoV-2. A detailed table is reported to easily guide readers toward the "right" choice depending on the virus of interest.

Development of a Point-of-Care Assay for HIV-1 Viral Load Using Higher Refractive Index Antibody-Coated Microbeads.

The detection of viruses using imaging techniques is challenging because of the weak scattering of light generated by the targets of sizes in the nanometer range. The system we have developed overcomes the light scattering problems by utilizing antibody-coated microbeads of higher index of refraction that can specifically bind with viruses and increase the acceptance angle. Using the new technology, we have developed a portable, cost-effective, and field-deployable platform for the rapid quantification of HIV-1 viral load for point-of-care (POC) settings. The system combines microfluidics with a wide field of view lensless imaging technology. Highly specific antibodies are functionalized to a glass slide inside a microchip to capture HIV-1 virions. The captured virions are then bound by antibody-conjugated microbeads, which have a higher refraction index. The microbeads-HIV-1 virions complexes generate diffraction patterns that are detected with a custom-built imaging setup and rapidly and accurately quantified by computational analysis. This platform technology enables fast nanoscale virus imaging and quantification from biological samples and thus can play a significant role in the detection and management of viral diseases.

Design, Development, and Performance Comparison of Wide Field Lensless and Lens-Based Optical Systems for Point-of-Care Biological Applications.

Lensless biological imaging systems are an emerging alternative to conventional microscopic systems because they enable a wide field of view imaging. While most microscopic systems sacrifice the field of view for magnification, lensless systems have taken advantage of small imaging pixel size, projection, digital magnification, and post-processing to compensate for diffracted images. A new lens-based system is designed to have the exact same wide field of view as that of a basic lensless setup. A new compound lens system design is utilized to achieve an explicit aim to have the same fields of view as the lensless setup. Then the characteristics of these two optical imaging setups (lensless and lens-based setups) are compared at this level of complexity to see what the minimal systems principles are needed to achieve the biological imaging goals for simplified and less expensive future designs. For both imaging systems, images of biological entities are recorded with the help of the same CMOS imaging device and computer software. The main contribution of this work is an exhaustive comparison between the performance characteristics of both systems using optical standards and biological images.

Development of a Microfluidic Device for CD4+ T Cell Isolation and Automated Enumeration from Whole Blood.

The development of point-of-care, cost-effective, and easy-to-use assays for the accurate counting of CD4+ T cells remains an important focus for HIV-1 disease management. The CD4+ T cell count provides an indication regarding the overall success of HIV-1 treatments. The CD4+ T count information is equally important for both resource-constrained regions and areas with extensive resources. Hospitals and other allied facilities may be overwhelmed by epidemics or other disasters. An assay for a physician's office or other home-based setting is becoming increasingly popular. We have developed a technology for the rapid quantification of CD4+ T cells. A double antibody selection process, utilizing anti-CD4 and anti-CD3 antibodies, is tested and provides a high specificity. The assay utilizes a microfluidic chip coated with the anti-CD3 antibody, having an improved antibody avidity. As a result of enhanced binding, a higher flow rate can be applied that enables an improved channel washing to reduce non-specific bindings. A wide-field optical imaging system is also developed that provides the rapid quantification of cells. The designed optical setup is portable and low-cost. An ImageJ-based program is developed for the automatic counting of CD4+ T cells. We have successfully isolated and counted CD4+ T cells with high specificity and efficiency greater than 90%.

Smartphone-based sickle cell disease detection and monitoring for point-of-care settings.

Sickle cell disease (SCD) is a worldwide hematological disorder causing painful episodes, anemia, organ damage, stroke, and even deaths. It is more common in sub-Saharan Africa and other resource-limited countries. Conventional laboratory-based diagnostic methods for SCD are time-consuming, complex, and cannot be performed at point-of-care (POC) and home settings. Optical microscope-based classification and counting demands a significant amount of time, extensive setup, and cost along with the skilled human labor to distinguish the normal red blood cells (RBCs) from sickled cells. There is an unmet need to develop a POC and home-based test to diagnose and monitor SCD and reduce mortality in resource-limited settings. An early-stage and timely diagnosis of SCD can help in the effective management of the disease. In this article, we utilized a smartphone-based image acquisition method for capturing RBC images from the SCD patients in normoxia and hypoxia conditions. A computer algorithm is developed to differentiate RBCs from the patient's blood before and after cell sickling. Using the developed smartphone-based technique, we obtained similar percentage of sickle cells in blood samples as analyzed by conventional method (standard microscope). The developed method of testing demonstrates the potential utility of the smartphone-based test for reducing the overall cost of screening and management for SCD, thus increasing the practicality of smartphone-based screening technique for SCD in low-resource settings. Our setup does not require any special storage requirements. This is the characteristic advantage of our technique as compared to other hemoglobin-based POC diagnostic techniques.

Development of a Flow-Free Automated Colorimetric Detection Assay Integrated with Smartphone for Zika NS1.

The Zika virus (ZIKV) is an emerging flavivirus transmitted to humans by Aedes mosquitoes that can potentially cause microcephaly, Guillain-Barré Syndrome, and other birth defects. Effective vaccines for Zika have not yet been developed. There is a necessity to establish an easily deployable, high-throughput, low-cost, and disposable point-of-care (POC) diagnostic platform for ZIKV infections. We report here an automated magnetic actuation platform suitable for a POC microfluidic sandwich enzyme-linked immunosorbent assay (ELISA) using antibody-coated superparamagnetic beads. The smartphone integrated immunoassay is developed for colorimetric detection of ZIKV nonstructural protein 1 (NS1) antigen using disposable chips to accommodate the reactions inside the chip in microliter volumes. An in-house-built magnetic actuator platform automatically moves the magnetic beads through different aqueous phases. The assay requires a total of 9 min to automatically control the post-capture washing, horseradish peroxidase (HRP) conjugated secondary antibody probing, washing again, and, finally, color development. By measuring the saturation intensity of the developed color from the smartphone captured video, the presented assay provides high sensitivity with a detection limit of 62.5 ng/mL in whole plasma. These results advocate a great promise that the platform would be useful for the POC diagnosis of Zika virus infection in patients and can be used in resource-limited settings.

Development of a Flow-Free Magnetic Actuation Platform for an Automated Microfluidic ELISA.

There is a need to create an easily deployable and point-of-care (POC) diagnostic platform for disease outbreaks and for monitoring and maintenance of chronic illnesses. Such platforms are useful in regions where access to clinical laboratories may be limited or constrained using cost-effective solutions to quickly process high numbers of samples. Using oil and water liquid-liquid interphase separation, immunoassays developed for microfluidic chips can potentially meet this need when leveraged with electromagnetic actuation and antibody-coated superparamagnetic beads. We have developed a microfluidic immunoassay detection platform, which enables assay automation and maintains successful liquid containment for future use in the field. The assay was studied through a series of magnetic and fluid simulations to demonstrate these optimizations, and an optimized chip was tested using a target model for HIV-1, the p24 capsid antigen. The use of minimal reagents further lowers the cost of each assay and lowers the required sample volume for testing (<50 µL), that can offer easy turnaround for sample collection and assay results. The developed microfluidic immunoassay platform can be easily scaled for multiplex or multi-panel specific testing at the POC.

Development of a multiplex fully automated assay for rapid quantification of CD4+ T cells from whole blood.

The development of cost-effective and rapid assays for the accurate counting of CD4 cells has remained prime focus for disease management. The lack of such assays has severely affected people living in resource-limited disease prevalent areas. CD4 count information plays a vital role in the effective management of HIV disease. There is an unmet need to develop rapid, cost-effective, portable and user-friendly point-of-care (POC) disease diagnostic platform technology for CD4+ T cell counting. Here, we have developed a flow-free magnetic actuation platform that uses antibody-coated magnetic beads to efficiently capture CD4+ T cells from a 30 µL drop of whole blood. On-chip cell lysate electrical impedance spectroscopy has been utilized to quantify the isolated CD4 cells. The developed assay has a limit of detection of 25 cells per µL and provides accurate CD4 counts in the range of 25-800 cells per µL. The whole immunoassay along with the enumeration process is very rapid and provides CD4 quantification results within 5 min time frame. The assay does not require off-chip sample preparation steps and minimizes human involvement to a greater extent. The developed impedance-based immunoassay has potential to significantly improve the CD4 enumeration process especially for POC settings.

Microfluidic Chip for Detection of Fungal Infections.

Fungal infections can lead to severe clinical outcomes such as multiple organ failure and septic shock. Rapid detection of fungal infections allows clinicians to treat patients in a timely manner and improves clinical outcomes. Conventional detection methods include blood culture followed by plate culture and polymerase chain reaction. These methods are time-consuming and require expensive equipment, hence, they are not suitable for point-of-care and clinical settings. There is an unmet need to develop a rapid and inexpensive detection method for fungal infections such as candidemia. We developed an innovative immuno-based microfluidic device that can rapidly detect and capture Candida albicans from phosphate-buffered saline (PBS) and human whole blood. Our microchip technology showed an efficient capture of C. albicans in PBS with an efficiency of 61-78% at various concentrations ranging from 10 to 105 colony-forming units per milliliter (cfu/mL). The presented microfluidic technology will be useful to screen for various pathogens at the point-of-care and clinical settings.

Paper-based analytical devices for clinical diagnosis: recent advances in the fabrication techniques and sensing mechanisms.

INTRODUCTION: There is a significant interest in developing inexpensive portable biosensing platforms for various applications including disease diagnostics, environmental monitoring, food safety, and water testing at the point-of-care (POC) settings. Current diagnostic assays available in the developed world require sophisticated laboratory infrastructure and expensive reagents. Hence, they are not suitable for resource-constrained settings with limited financial resources, basic health infrastructure, and few trained technicians. Cellulose and flexible transparency paper-based analytical devices have demonstrated enormous potential for developing robust, inexpensive and portable devices for disease diagnostics. These devices offer promising solutions to disease management in resource-constrained settings where the vast majority of the population cannot afford expensive and highly sophisticated treatment options. Areas covered: In this review, the authors describe currently developed cellulose and flexible transparency paper-based microfluidic devices, device fabrication techniques, and sensing technologies that are integrated with these devices. The authors also discuss the limitations and challenges associated with these devices and their potential in clinical settings. Expert commentary: In recent years, cellulose and flexible transparency paper-based microfluidic devices have demonstrated the potential to become future healthcare options despite a few limitations such as low sensitivity and reproducibility.