Thousand-fold fluorescent signal amplification for mHealth diagnostics

Genosensors as an alternative diagnostic sensing approaches for specific detection of various certain viruses: a review of common techniques and outcomes

Viral infections are responsible for the deaths of millions of people throughout the world. Since outbreak of highly contagious and mutant viruses such as contemporary sars-cov-2 pandemic, has challenged the conventional diagnostic methods, the entity of a thoroughly sensitive, specific, rapid and inexpensive detecting technique with minimum level of false-positivity or -negativity, is desperately needed more than any time in the past decades. Biosensors as minimized devices could detect viruses in simple formats. So far, various nucleic acid, immune- and protein-based biosensors were designed and tested for recognizing the genome, antigen, or protein level of viruses, respectively; however, nucleic acid-based sensing techniques, which is the foundation of constructing genosensors, are preferred not only because of their ultra-sensitivity and applicability in the early stages of infections but also for their ability to differentiate various strains of the same virus. To date, the review articles related to genosensors are just confined to particular pathogenic diseases; In this regard, the present review covers comprehensive information of the research progress of the electrochemical, optical, and surface plasmon resonance (SPR) genosensors that applied for human viruses' diseases detection and also provides a well description of viruses' clinical importance, the conventional diagnosis approaches of viruses and their disadvantages. This review would address the limitations in the current developments as well as the future challenges involved in the successful construction of sensing approaches with the functionalized nanomaterials and also allow exploring into core-research works regarding this area.

Smartphone-based clinical diagnostics: towards democratization of evidence-based health care

Recent advancements in bioanalytical techniques have led to the development of novel and robust diagnostic approaches that hold promise for providing optimal patient treatment, guiding prevention programs and widening the scope of personalized medicine. However, these advanced diagnostic techniques are still complex, expensive and limited to centralized healthcare facilities or research laboratories. This significantly hinders the use of evidence-based diagnostics for resource-limited settings and the primary care, thus creating a gap between healthcare providers and patients, leaving these populations without access to precision and quality medicine. Smartphone-based imaging and sensing platforms are emerging as promising alternatives for bridging this gap and decentralizing diagnostic tests offering practical features such as portability, cost-effectiveness and connectivity. Moreover, towards simplifying and automating bioanalytical techniques, biosensors and lab-on-a-chip technologies have become essential to interface and integrate these assays, bringing together the high precision and sensitivity of diagnostic techniques with the connectivity and computational power of smartphones. Here, we provide an overview of the emerging field of clinical smartphone diagnostics and its contributing technologies, as well as their wide range of areas of application, which span from haematology to digital pathology and rapid infectious disease diagnostics.

Streak Imaging Flow Cytometer for Rare Cell Analysis

There is a need for simple and affordable techniques for cytology for clinical applications, especially for point-of-care (POC) medical diagnostics in resource-poor settings. However, this often requires adapting expensive and complex laboratory-based techniques that often require significant power and are too massive to transport easily. One such technique is flow cytometry, which has great potential for modification due to the simplicity of the principle of optical tracking of cells. However, it is limited in that regard due to the flow focusing technique used to isolate cells for optical detection. This technique inherently reduces the flow rate and is therefore unsuitable for rapid detection of rare cells which require large volume for analysis.To address these limitations, we developed a low-cost, mobile flow cytometer based on streak imaging. In our new configuration we utilize a simple webcam for optical detection over a large area associated with a wide-field flow cell. The new flow cell is capable of larger volume and higher throughput fluorescence detection of rare cells than the flow cells with hydrodynamic focusing used in conventional flow cytometry. The webcam is an inexpensive, commercially available system, and for fluorescence analysis we use a 1 W 450 nm blue laser to excite Syto-9 stained cells with emission at 535 nm. We were able to detect low concentrations of stained cells at high flow rates of 10 mL/min, which is suitable for rapidly analyzing larger specimen volumes to detect rare cells at appropriate concentration levels. The new rapid detection capabilities, combined with the simplicity and low cost of this device, suggest a potential for clinical POC flow cytometry in resource-poor settings associated with global health.

Low-Cost Charged-Coupled Device (CCD) Based Detectors for Shiga Toxins Activity Analysis

To improve food safety there is a need to develop simple, low-cost sensitive devices for detection of food-borne pathogens and their toxins. We describe a simple, low-cost webcam-based detector which can be used for various optical detection modalities, including fluorescence, chemiluminescence, densitometry, and colorimetric assays. The portable battery-operated CCD-based detection system consists of four modules: (1) a webcam to measure and record light emission, (2) a sample plate to perform assays, (3) a light emitting diode (LED) for illumination, and (4) a portable computer to acquire and analyze images. To demonstrate the technology, we used a cell based assay for fluorescence detection of the activity of the food borne Shiga toxin type 2 (Stx2), differentiating between biologically active toxin and inactive toxin which is not a risk. The assay is based on Shiga toxin inhibition of cell protein synthesis measured through inhibition of the green fluorescent protein (GFP). In this assay, GFP emits light at 509 nm when excited with a blue LED equipped with a filter at 486 nm. The emitted light is then detected with a green filter at 535 nm. Toxin activity is measured through a reduction in the 509 nm emission. In this system the level of detection (LOD) for Stx2 was 0.1 pg/ml, similar to the LOD of commercial fluorometers. These results demonstrate the utility and potential of low cost detectors for toxin activity. This approach could be readily adapted to the detection of other food-borne toxins.

Ultrasensitive, rapid and inexpensive detection of DNA using paper based lateral flow assay

Sensitive, specific, rapid, inexpensive and easy-to-use nucleic acid tests for use at the point-of-need are critical for the emerging field of personalised medicine for which companion diagnostics are essential, as well as for application in low resource settings. Here we report on the development of a point-of-care nucleic acid lateral flow test for the direct detection of isothermally amplified DNA. The recombinase polymerase amplification method is modified slightly to use tailed primers, resulting in an amplicon with a duplex flanked by two single stranded DNA tails. This tailed amplicon facilitates detection via hybridisation to a surface immobilised oligonucleotide capture probe and a gold nanoparticle labelled reporter probe. A detection limit of 1 × 10^-11 M (190 amol), equivalent to 8.67 × 10⁵ copies of DNA was achieved, with the entire assay, both amplification and detection, being completed in less than 15 minutes at a constant temperature of 37 °C. The use of the tailed primers obviates the need for hapten labelling and consequent use of capture and reporter antibodies, whilst also avoiding the need for any post-amplification processing for the generation of single stranded DNA, thus presenting an assay that can facilely find application at the point of need.

The role of interdisciplinary research team in the impact of health apps in health and computer science publications: a systematic review

BACKGROUND

Several studies have estimated the potential economic and social impact of the mHealth development. Considering the latest study by Institute for Healthcare Informatics, more than 165.000 apps of health and medicine are offered including all the stores from different platforms. Thus, the global mHealth market was an estimated $10.5 billion in 2014 and is expected to grow 33.5 percent annually between 2015 and 2020s. In fact, apps of Health have become the third-fastest growing category, only after games and utilities.

METHODS

This study aims to identify, study and evaluate the role of interdisciplinary research teams in the development of articles and applications in the field of mHealth. It also aims to evaluate the impact that the development of mHealth has had on the health and computer science field, through the study of publications in specific databases for each area which have been published until nowadays.

RESULTS

Interdisciplinary nature is strongly connected to the scientific quality of the journal in which the work is published. This way, there are significant differences in those works that are made up by an interdisciplinary research team because of they achieve to publish in journals with higher quartiles. There are already studies that warn of methodological deficits in some studies in mHealth, low accuracy and no reproducibility. Studies of low precision and poor reproducibility, coupled with the low evidence, provide low degrees of recommendation of the interventions targeted and therefore low applicability.

CONCLUSIONS

From the evidence of this study, working in interdisciplinary groups from different areas greatly enhances the quality of research work as well as the quality of the publications derived from its results.

Improving the Sensitivity and Functionality of Mobile Webcam-Based Fluorescence Detectors for Point-of-Care Diagnostics in Global Health

Resource-poor countries and regions require effective, low-cost diagnostic devices for accurate identification and diagnosis of health conditions. Optical detection technologies used for many types of biological and clinical analysis can play a significant role in addressing this need, but must be sufficiently affordable and portable for use in global health settings. Most current clinical optical imaging technologies are accurate and sensitive, but also expensive and difficult to adapt for use in these settings. These challenges can be mitigated by taking advantage of affordable consumer electronics mobile devices such as webcams, mobile phones, charge-coupled device (CCD) cameras, lasers, and LEDs. Low-cost, portable multi-wavelength fluorescence plate readers have been developed for many applications including detection of microbial toxins such as C. Botulinum A neurotoxin, Shiga toxin, and S. aureus enterotoxin B (SEB), and flow cytometry has been used to detect very low cell concentrations. However, the relatively low sensitivities of these devices limit their clinical utility. We have developed several approaches to improve their sensitivity presented here for webcam based fluorescence detectors, including (1) image stacking to improve signal-to-noise ratios; (2) lasers to enable fluorescence excitation for flow cytometry; and (3) streak imaging to capture the trajectory of a single cell, enabling imaging sensors with high noise levels to detect rare cell events. These approaches can also help to overcome some of the limitations of other low-cost optical detection technologies such as CCD or phone-based detectors (like high noise levels or low sensitivities), and provide for their use in low-cost medical diagnostics in resource-poor settings.

The Assessment of the Readiness of Molecular Biomarker-Based Mobile Health Technologies for Healthcare Applications

Mobile health technologies to detect physiological and simple-analyte biomarkers have been explored for the improvement and cost-reduction of healthcare services, some of which have been endorsed by the US FDA. Advancements in the investigations of non-invasive and minimally-invasive molecular biomarkers and biomarker candidates and the development of portable biomarker detection technologies have fuelled great interests in these new technologies for mhealth applications. But apart from the development of more portable biomarker detection technologies, key questions need to be answered and resolved regarding to the relevance, coverage, and performance of these technologies and the big data management issues arising from their wide spread applications. In this work, we analyzed the newly emerging portable biomarker detection technologies, the 664 non-invasive molecular biomarkers and the 592 potential minimally-invasive blood molecular biomarkers, focusing on their detection capability, affordability, relevance, and coverage. Our analysis suggests that a substantial percentage of these biomarkers together with the new technologies can be potentially used for a variety of disease conditions in mhealth applications. We further propose a new strategy for reducing the workload in the processing and analysis of the big data arising from widespread use of mhealth products, and discuss potential issues of implementing this strategy.

Webcam-based flow cytometer using wide-field imaging for low cell number detection at high throughput

Here we describe a novel low-cost flow cytometer based on a webcam capable of low cell number detection in a large volume which may overcome the limitations of current flow cytometry. Several key elements have been combined to yield both high throughput and high sensitivity. The first element is a commercially available webcam capable of 187 frames per second video capture at a resolution of 320 × 240 pixels. The second element in this design is a 1 W 450 nm laser module for area-excitation, which combined with the webcam allows for rapid interrogation of a flow field. The final element is a 2D flow-cell which overcomes the flow limitation of hydrodynamic focusing and allows for higher sample throughput in a wider flow field. This cell allows for the linear velocity of target cells to be lower than in a conventional "1D" hydrodynamic focusing flow-cells typically used in cytometry at similar volumetric flow rates. It also allows cells to be imaged at the full frame rate of the webcam. Using this webcam-based flow cytometer with wide-field imaging, it was confirmed that the detection of fluorescently tagged 5 μm polystyrene beads in "1D" hydrodynamic focusing flow-cells was not practical for low cell number detection due to streaking from the motion of the beads, which did not occur with the 2D flow-cell design. The sensitivity and throughput of this webcam-based flow cytometer was then investigated using THP-1 human monocytes stained with SYTO-9 florescent dye in the 2D flow-cell. The flow cytometer was found to be capable of detecting fluorescently tagged cells at concentrations as low as 1 cell per mL at flow rates of 500 μL min(-1) in buffer and in blood. The effectiveness of detection was concentration dependent: at 100 cells per mL 84% of the cells were detected compared to microscopy, 10 cells per mL 79% detected and 1 cell per mL 59% of the cells were detected. With the blood samples spiked to 100 cells per mL, the average concentration for all samples was 91.4 cells per mL, with a 95% confidence interval of 86-97 cells per mL. These low cell concentrations and the large volume capabilities of the system may overcome the limitations of current cytometry, and are applicable to rare cell (such as circulating tumor cell) detection The simplicity and low cost of this device suggests that it may have a potential use in developing point-of-care clinical flow cytometry for resource-poor settings associated with global health.

Emerging technologies for biomedical analysis

Options for biomedical analysis continue to evolve from many fields of study, employing diverse detection and quantification methods. New technologies in this arena focus on improving the sensitivity of analysis and the speed of testing, as well as producing systems at low cost which can be used on site as a point-of-care device for telemedicine applications. In this article, the most important original experimental platforms as well as current commercial approaches to biomedical analysis are critically chosen and reviewed, covering January 2010 to January 2014. While literature is quite broad and numerous, there is clear emphasis on biological recognition and imaging for the most impactful works. The analytical approaches are discussed in terms of their utility in diagnostics and biomedical testing.

Opto-fluidics based microscopy and flow cytometry on a cell phone for blood analysis

Blood analysis is one of the most important clinical tests for medical diagnosis. Flow cytometry and optical microscopy are widely used techniques to perform blood analysis and therefore cost-effective translation of these technologies to resource limited settings is critical for various global health as well as telemedicine applications. In this chapter, we review our recent progress on the integration of imaging flow cytometry and fluorescent microscopy on a cell phone using compact, light-weight and cost-effective opto-fluidic attachments integrated onto the camera module of a smartphone. In our cell-phone based opto-fluidic imaging cytometry design, fluorescently labeled cells are delivered into the imaging area using a disposable micro-fluidic chip that is positioned above the existing camera unit of the cell phone. Battery powered light-emitting diodes (LEDs) are butt-coupled to the sides of this micro-fluidic chip without any lenses, which effectively acts as a multimode slab waveguide, where the excitation light is guided to excite the fluorescent targets within the micro-fluidic chip. Since the excitation light propagates perpendicular to the detection path, an inexpensive plastic absorption filter is able to reject most of the scattered light and create a decent dark-field background for fluorescent imaging. With this excitation geometry, the cell-phone camera can record fluorescent movies of the particles/cells as they are flowing through the microchannel. The digital frames of these fluorescent movies are then rapidly processed to quantify the count and the density of the labeled particles/cells within the solution under test. With a similar opto-fluidic design, we have recently demonstrated imaging and automated counting of stationary blood cells (e.g., labeled white blood cells or unlabeled red blood cells) loaded within a disposable cell counting chamber. We tested the performance of this cell-phone based imaging cytometry and blood analysis platform by measuring the density of red and white blood cells as well as hemoglobin concentration in human blood samples, which showed a good match to our measurement results obtained using a commercially available hematology analyzer. Such a cell-phone enabled opto-fluidics microscopy, flow cytometry, and blood analysis platform could be especially useful for various telemedicine applications in remote and resource-limited settings.

Improving lateral-flow immunoassay (LFIA) diagnostics via biomarker enrichment for mHealth

Optical detection technologies based on mobile devices can be utilized to enable many mHealth applications, including a reader for lateral-flow immunoassay (LFIA). However, an intrinsic challenge associated with LFIA for clinical diagnostics is the limitation in sensitivity. Therefore, rapid and simple specimen processing strategies can directly enable more sensitive LFIA by purifying and concentrating biomarkers. Here, a binary reagent system is presented for concentrating analytes from a larger volume specimen to improve the malaria LFIA's limit of detection (LOD). The biomarker enrichment process utilizes temperature-responsive gold-streptavidin conjugates, biotinylated antibodies, and temperature-responsive magnetic nanoparticles. The temperature-responsive gold colloids were synthesized by modifying the citrate-stabilized gold colloids with a diblock copolymer, containing a thermally responsive poly(N-isopropylacrylamide) (pNIPAAm) segment and a gold-binding block composed of NIPAAm-co-N,N-dimethylaminoethylacrylamide. The gold-streptavidin conjugates were synthesized by conjugating temperature-responsive gold colloids with streptavidin via covalent linkages using carbodiimide chemistry chemistry. The gold conjugates formed half-sandwiches, gold labeled biomarker, by complexing with biotinylated antibodies that were bound to Plasmodium falciparum histidine-rich protein 2 (PfHRP2), a malaria antigen. When a thermal stimulus was applied in conjunction with a magnetic field, the half-sandwiches and temperature-responsive magnetic nanoparticles that were both decorated with pNIPAAm formed large aggregates that were efficiently magnetically separated from human plasma. The binary reagent system was applied to a large volume (500 μL) specimen for concentrating biomarker 50-fold into a small volume and applied directly to an off-the-shelf malaria LFIA to improve the signal-to-noise ratio.

Smartphone-based fluorescence detector for mHealth

We describe here a compact smartphone-based fluorescence detector for mHealth. A key element to achieving high sensitivity using low sensitivity phone cameras is a capillary array, which increases sensitivity by 100×. The capillary array was combined with a white LED illumination system to enable wide spectra fluorescent excitation in the range of 450-740 nm. The detector utilizes an orthographic projection system to form parallel light projection images from the capillaries at a close distance via an object-space telecentric lens configuration that reduces the total lens-to-object distance while maintaining uniformity in measurement between capillaries. To further increase the limit of detection (LOD), a computational image processing approach was employed to decrease the level of noise. This enables an additional 5-10× decrease in LOD. This smartphone-based detector was used to measure serial dilutions of fluorescein with a LOD of 1 nM with image stacking and 10 nM without image stacking, similar to the LOD obtained with a commercial plate reader. Moreover, the capillary array required a sample volume of less than 10 μl, which is an order of magnitude less than the 100 μl required for the plate reader.As fluorescence detection is widely used in sensitive biomedical assays, the approach described here has the potential to increase mHealth clinical utility, especially for telemedicine and for resource-poor settings in global health applications.

Mobile flow cytometer for mHealth

Flow cytometry is used for cell counting and analysis in numerous clinical and environmental applications. However flow cytometry is not used in mHealth mainly because current flow cytometers are large, expensive, power-intensive devices designed to operate in a laboratory. Their design results in a lack of portability and makes them unsuitable for mHealth applications. Another limitation of current technology is the low volumetric throughput rates that are not suitable for rapid detection of rare cells.To address these limitations, we describe here a novel, low-cost, mobile flow cytometer based on wide-field imaging with a webcam for large volume and high throughput fluorescence detection of rare cells as a simulation for circulating tumor cells (CTCs) detection. The mobile flow cytometer uses a commercially available webcam capable of 187 frames per second video capture at a resolution of 320 × 240 pixels. For fluorescence detection, a 1 W 450 nm blue laser is used for excitation of Syto-9 fluorescently stained cells detected at 535 nm. A wide-field flow cell was developed for large volume analysis that allows for the linear velocity of target cells to be lower than in conventional hydrodynamic focusing flow cells typically used in cytometry. The mobile flow cytometer was found to be capable of detecting low concentrations at flow rates of 500 μL/min, suitable for rare cell detection in large volumes. The simplicity and low cost of this device suggests that it may have a potential clinical use for mHealth flow cytometry for resource-poor settings associated with global health.

Transformation of personal computers and mobile phones into genetic diagnostic systems

Molecular diagnostics based on the polymerase chain reaction (PCR) offer rapid and sensitive means for detecting infectious disease, but prohibitive costs have impeded their use in resource-limited settings where such diseases are endemic. In this work, we report an innovative method for transforming a desktop computer and a mobile camera phone--devices that have become readily accessible in developing countries--into a highly sensitive DNA detection system. This transformation was achieved by converting a desktop computer into a de facto thermal cycler with software that controls the temperature of the central processing unit (CPU), allowing for highly efficient PCR. Next, we reconfigured the mobile phone into a fluorescence imager by adding a low-cost filter, which enabled us to quantitatively measure the resulting PCR amplicons. Our system is highly sensitive, achieving quantitative detection of as little as 9.6 attograms of target DNA, and we show that its performance is comparable to advanced laboratory instruments at approximately 1/500th of the cost. Finally, in order to demonstrate clinical utility, we have used our platform for the successful detection of genomic DNA from the parasite that causes Chagas disease, Trypanosoma cruzi, directly in whole, unprocessed human blood at concentrations 4-fold below the clinical titer of the parasite.