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Immunoassay protocol and working principle of the MCFA chip. a Schematic of the immunoassay protocol for chemiluminescence based sandwich ELISA as implemented on the lab chip, b Schematic of the immunoassay reactions occurring in the test reaction chamber, positive control chamber and negative control chamber (from left to right) and c Sequential working principle of the MCFA device where (i) shows the empty test chamber immobilized with capture antibody, (ii) shows the condition when HRP-DAb-antigen complex reaches the test chamber, (iii) depicts the formation of Cab-antigen-DAb complex after adequate washing and (iv) illustrates the condition when the substrate reaches the test chamber producing chemiluminescence
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There has been a considerable development in microfluidic based immunodiagnostics over the past few years which has greatly favored the growth of novel point-of-care-testing (POCT). However, the realization of an inexpensive, low-power POCT needs cheap and disposable microfluidic devices that can perform autonomously with minimum user intervention....
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Context 1
... to flow and bind with the immobilized capture antibody in the reaction chambers. A hydrophobic vent connected to path-2, when opened, helps in the escape of the trapped air and allows the reconstituted substrate to reach the reaction chamber causing chemiluminescence. The immunoassay protocol for chemiluminescence based sandwich ELISA is shown in Fig. 2a. The micro-pillared reservoir and the meandering channel following the reaction chambers slow down the flow rate and provide longer reaction time between the antibodies and target antigen and increase the assay sensitivity. The capillary pump is designed to have a very high capillary pressure that facilitates washing of unbound ...
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... performance. Dimensions and volume of MCFA lab chip channels and reservoirs are summarized in Table 1. Three reaction chambers were designed to act as test reaction chamber, positive control and negative control to perform quality control on the MCFA lab chip. The immunoassay reactions occurring on the three reaction chambers is explained in Fig. 2b. The chemiluminescence signal obtained from the test chamber can be directly correlated to the biomarker concentration whereas the positive control validates the functionality of the HRP-conjugated Dab. The negative control provides the blank for each operation ensuring chip validation. The microfluidic channels were designed to obtain ...
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... control provides the blank for each operation ensuring chip validation. The microfluidic channels were designed to obtain different capillary pressure at different areas to enable a seamless flow of the sample from the loading chamber to the capillary pump while maintaining the sequence of chemiluminescence based sandwich assay as depicted in Fig. 2c. Based on the test reaction chamber volume of 2.5 μl, the lyophilization chambers, the sample loading chamber and the capillary pump were designed to have sufficient volumes to facilitate the immunoassay ...
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... sandwich ELISA for the detection of malaria biomarker PfHRP2, which followed the assay protocol described in Fig. 2a, was performed using anti-PfHRP2 capture antibody (MPFM-55A), HRP conjugated antiPfHRP2 detection antibody (MPFG-55P) and purified PfHRP2 protein (AG55-0092-Z), all obtained from Immunology Consultants Laboratory (ICL), Inc., USA. Uniglow TM one-component chemiluminescent (CL) substrate, Uniglow-0100 (Rockland antibodies and assay, ...
Citations
... They are made of arrays of integrated single-photon avalanche diodes (SPADs) [28], whose suitability for chemiluminescence-based detection of circulating biomarkers has already been demonstrated [29]. The use of a high-sensitivity photodetector operating at room temperature with an area of the order of square millimeters, such as a SiPM, allows to remove any lens or optical system or cooling need with the huge advantage of obtaining a low-cost, simple, compact, and ultrasensitive device [30][31][32][33]. ...
The identification and quantification of biomarkers with innovative technologies is an urgent need for the precise diagnosis and follow up of human diseases. Body fluids offer a variety of informative biomarkers, which are traditionally measured with time-consuming and expensive methods. In this context, lateral flow tests (LFTs) represent a rapid and low-cost technology with a sensitivity that is potentially improvable by chemiluminescence biosensing. Here, an LFT based on gold nanoparticles functionalized with antibodies labeled with the enzyme horseradish peroxidase is combined with a lensless biosensor. This biosensor comprises four Silicon Photomultipliers (SiPM) coupled in close proximity to the LFT strip. Microfluidics for liquid handling complete the system. The development and the setup of the biosensor is carefully described and characterized. C-reactive protein was selected as a proof-of-concept biomarker to define the limit of detection, which resulted in about 0.8 pM when gold nanoparticles were used. The rapid readout (less than 5 min) and the absence of sample preparation make this biosensor promising for the direct and fast detection of human biomarkers.
... CL assays are particularly suited for the development of miniaturized and portable analytical devices, as the instrumentation required for the readout of the CL signal is very simple, mainly requiring a photon detection device and a dark chamber to avoid interference from ambient light. Indeed, light imaging systems based on a charge-coupled device (CCD) camera [44][45][46] or even a smartphone's complementary metal-oxide semiconductor (CMOS) sensor [47][48][49][50][51] were employed and integrated into a compact and portable device for photon detection [39]. ...
New cosmetic formulations are continuously requested by the market and the ingredients are constantly evolving. Recently the use of antioxidants has gained success and, in this context, analytical methods able to quickly and easily assess the antioxidant activity of cosmetics would make it possible to carry out analyses on new formulations even within the manufacturing process without the need for specialized laboratories and personnel, thus evaluating directly on-site the effectiveness and the shelf life of products. In this work, a chemiluminescent inhibition assay was developed for determining the total antioxidant activity in cosmetic products. The method was based on the luminol/enhancers/hydrogen peroxide/horseradish peroxidase chemiluminescent system, which generates light signals measurable through simple and compact instrumentation. The formation of the chemiluminescent signal is inhibited by the presence of antioxidant substances while it is restored once all the antioxidant molecules have been oxidized. The time of appearance of the light signal is related to the total antioxidant activity. The assay was carried out exploiting an integrated device comprising a microwell plate coupled with an array of amorphous silicon hydrogenated photosensors enclosed in a mini-dark box. The method was optimized in terms of concentrations and volumes of the required reagents and sample pre-treatment. A calibration curve was generated taking as a reference the antioxidant activity of ascorbic acid obtaining a detection limit of 10 µM. The developed method was applied to cosmetic products currently on the market as well as on spiked samples in order to evaluate the performance of the methods in terms of sensitivity, accuracy, and reproducibility.
... 19 ). c A microfluidic capillary device (figure adapted with permission from Ghosh et al. 47 ). d A microfluidic finger-pump device (figure adapted with permission from Comina et al. ...
... To overcome this issue, researchers have developed innovative micropumps, such as capillary, finger, and passive vacuum pumps [41][42][43][44][45][46] , for driving fluid on mHealth platforms. Ghosh et al. demonstrated a microfluidic chip containing a capillary pump for microchannel capillary flow assay (MCFA) on a mHealth platform 47 . The immunoassay on the chip was entirely controlled by channel geometry and surface properties without any external pumping (Fig. 2c). ...
... The global SARS-CoV-2 pandemic has led to a high demand for point-of-care testing (POCT) devices 79 . Microfluidic POCT platforms simplify analyses by integrating multiple procedures, such as sampling, chemical reactions, chromatographic separation and detection into a small chip, enabling multiple analyses and providing a "sample-in-answer-out" function 80,81 . ...
In this paper, we review the integration of microfluidic chips and computer vision, which has great potential to advance research in the life sciences and biology, particularly in the analysis of cell imaging data. Microfluidic chips enable the generation of large amounts of visual data at the single-cell level, while computer vision techniques can rapidly process and analyze these data to extract valuable information about cellular health and function. One of the key advantages of this integrative approach is that it allows for noninvasive and low-damage cellular characterization, which is important for studying delicate or fragile microbial cells. The use of microfluidic chips provides a highly controlled environment for cell growth and manipulation, minimizes experimental variability and improves the accuracy of data analysis. Computer vision can be used to recognize and analyze target species within heterogeneous microbial populations, which is important for understanding the physiological status of cells in complex biological systems. As hardware and artificial intelligence algorithms continue to improve, computer vision is expected to become an increasingly powerful tool for in situ cell analysis. The use of microelectromechanical devices in combination with microfluidic chips and computer vision could enable the development of label-free, automatic, low-cost, and fast cellular information recognition and the high-throughput analysis of cellular responses to different compounds, for broad applications in fields such as drug discovery, diagnostics, and personalized medicine.
... In addition to exposing the healthcare personnel to a high risk of infection, 4 they increase the consumption of personal protective equipment. 2 The nasopharyngeal swab (NPS) collection method also causes discomfort to the patient 5 and is difficult to perform in patients with nasal pathology like gross deviated nasal septum. 6 Therefore there is a need for a simpler and less invasive method that reduces the risk to healthcare personnel and the economic and logistic burden on healthcare systems. ...
... The miniaturization and portability of smartphone-based detection devices have allowed for the avoidance of large-scale equipment such as fluorescence spectrometers and microplate readers. Meanwhile, smartphones can store and share data in real time, providing new opportunities for developing low-cost, portable fluorescence detection devices [23][24][25]. However, early disease diagnosis requires the detection of low concentrations of biomarkers, which provides a challenge for smartphone-based fluorescence devices [26]. ...
The sensitive and rapid detection of microsamples is crucial for early diagnosis of diseases. The short response times and low sample volume requirements of microfluidic chips have shown great potential in early diagnosis, but there are still shortcomings such as complex preparation processes and high costs. We developed a low-cost smartphone-based fluorescence detection device (Smartphone-BFDD) without precision equipment for rapid identification and quantification of biomarkers on glass capillary. The device combines microfluidic technology with RGB image analysis, effectively reducing the sample volume to 20 μL and detection time to only 30 min. For the sensitivity of the device, we constructed a standard sandwich immunoassay (antibody–antigen–antibody) in a glass capillary using the N-protein of SARS-CoV-2 as a biological model, realizing a low limit of detection (LOD, 40 ng mL−1). This device provides potential applications for different biomarkers and offers wide use for rapid biochemical analysis in biomedical research.
... Microfluidics can be preprogrammed by synchronizing the capillary pressure and flow resistance values 23,24 . Juncker et al. presented capillary circuits based on the sequential delivery of liquids using retention burst valves 20 . ...
By manipulating the geometry and surface chemistry of microfluidic channels, capillary-driven microfluidics can move and stop fluids spontaneously without external instrumentation. Furthermore, complex microfluidic circuits can be preprogrammed by synchronizing the capillary pressures and encoding the surface tensions of microfluidic chips. A key component of these systems is the capillary valve. However, the main concern for these valves is the presence of unwanted diffusion during the valve loading and activation steps that can cause cross-contamination. In this study, we design and validate a novel diffusion-free capillary valve: the π-valve. This valve consists of a 3D structure and a void area. The void acts as a spacer between two fluids to avoid direct contact. When the valve is triggered, the air trapped within the void is displaced by pneumatic suction induced from the capillary flow downstream without introducing a gas bubble into the circuit. The proposed design eliminates diffusive mixing before valve activation. Numerical simulation is used to study the function and optimize the dimensions of the π-valve, and 3D printing is used to fabricate either the mould or the microfluidic chip. A comparison with a conventional valve (based on a constriction-expansion valve) demonstrates that the π-valve eliminates possible backflow into the valve and reduces the mixing and diffusion during the loading and trigger steps. As a proof-of-concept, this valve is successfully implemented in a capillary-driven circuit for the determination of benzodiazepine, achieving the successive release of 3 solutions in a 3D-printed microfluidic chip without external instrumentation. The results show a 40% increase in the fluorescence intensity using the π-valve relative to the conventional value. Overall, the π-valve prevents cross-contamination, minimizes sample use, and facilitates a sophisticated preprogrammed release of fluids, offering a promising tool for conducting automated immunoassays applicable at point-of-care testing.
... A recent overview of the various types of microcontrollers used in the scientific field has been described by Prabhu and Urban and there have been a number of recent articles demonstrating how low-cost electronics can be integrated with chemical synthesis and continuous flow synthesis for substance detection. [7][8][9][10][11][12][13][14][15][16][17][18][19][20] ...
We describe the development of a digital modular 3D printed continuous flow system to carry out both classical and photochemical synthesis that uses a novel PC based software interface. Using this system, we describe how we were able to both control and monitor reaction conditions at the same time. The system integrates in-line sensors via a simple cassette based system that is analogous to a games console enabling hot-swopping of modules by a user. To control the system, an PC-interface platform was created to automate the control of the system functionality, as well as the reporting of sensor parameters. The utility of the system was demonstrated by performing a series of reactions highlighting the importance that precise control of solvent flow rate and accurate reporting of reaction temperatures can have on standardization and reproducibility and that the system can be easily modified to allow for scale-up synthesis.
... 19 ). c A microfluidic capillary device (figure adapted with permission from Ghosh et al. 47 ). d A microfluidic finger-pump device (figure adapted with permission from Comina et al. ...
... To overcome this issue, researchers have developed innovative micropumps, such as capillary, finger, and passive vacuum pumps [41][42][43][44][45][46] , for driving fluid on mHealth platforms. Ghosh et al. demonstrated a microfluidic chip containing a capillary pump for microchannel capillary flow assay (MCFA) on a mHealth platform 47 . The immunoassay on the chip was entirely controlled by channel geometry and surface properties without any external pumping (Fig. 2c). ...
The frequent outbreak of global infectious diseases has prompted the development of rapid and effective diagnostic tools for the early screening of potential patients in point-of-care testing scenarios. With advances in mobile computing power and microfluidic technology, the smartphone-based mobile health platform has drawn significant attention from researchers developing point-of-care testing devices that integrate microfluidic optical detection with artificial intelligence analysis. In this article, we summarize recent progress in these mobile health platforms, including the aspects of microfluidic chips, imaging modalities, supporting components, and the development of software algorithms. We document the application of mobile health platforms in terms of the detection objects, including molecules, viruses, cells, and parasites. Finally, we discuss the prospects for future development of mobile health platforms. Smartphone-based mobile health platforms have drawn increasing attention from researchers developing point-of-care testing devices. Here the authors summarize recent progress and future directions of approaches combining microfluidics and artificial intelligence.
... The sample volume can be reduced by almost 20-fold with the capillary force, which pulls the reagent into the reaction chamber during the immunoassay. This results in an overall reagent saving of 5-to 10-fold (Ghosh et al., 2020). The total assay time can also be lessened by 50%, which reduces the inclusive cost of labor (Thaitrong et al., 2013). ...
The coronavirus disease 2019 (COVID-19) pandemic has prompted a lot of questions globally regarding the range of information about the virus’s possible routes of transmission, diagnostics, and therapeutic tools. Worldwide studies have pointed out the importance of monitoring and early surveillance techniques based on the identification of viral RNA in wastewater. These studies indicated the presence of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA in human feces, which is shed via excreta including mucus, feces, saliva, and sputum. Subsequently, they get dumped into wastewater, and their presence in wastewater provides a possibility of using it as a tool to help prevent and eradicate the virus. Its monitoring is still done in many regions worldwide and serves as an early “warning signal”; however, a lot of limitations of wastewater surveillance have also been identified.
