Smartphone-based Device Research Articles

Diagnostic accuracy of a smartphone-based device (VistaView) for detection of diabetic retinopathy: A prospective study.

Diabetic retinopathy (DR) is a leading cause of blindness globally. The gold standard for DR screening is stereoscopic colour fundus photography with tabletop cameras. VistaView is a novel smartphone-based retinal camera which offers mydriatic retinal imaging. This study compares the diagnostic accuracy of the smartphone-based VistaView camera compared to a traditional desk mounted fundus camera (Triton Topcon). We also compare the agreement between graders for DR screening between VistaView images and Topcon images. This prospective study took place between December 2021 and June 2022 in Pakistan. Consecutive diabetic patients were imaged following mydriasis using both VistaView and Topcon cameras at the same sitting. All images were graded independently by two graders based on the International Classification of Diabetic Retinopathy (ICDR) criteria. Individual grades were assigned for severity of DR and maculopathy in each image. Diagnostic accuracy was calculated using the Topcon camera as the gold standard. Agreement between graders for each device was calculated as intraclass correlation coefficient (ICC) (95% CI) and Cohen's weighted kappa (k). A total of 1428 images were available from 371 patients with both cameras. After excluding ungradable images, a total of 1231 images were graded. The sensitivity of VistaView for any DR was 69.9% (95% CI 62.2-76.6%) while the specificity was 92.9% (95% CI 89.9-95.1%), and PPV and NPV were 80.5% (95% CI 73-86.4%) and 88.1% (95% CI 84.5-90.9) respectively. The sensitivity of VistaView for RDR was 69.7% (95% CI 61.7-76.8%) while the specificity was 94.2% (95% CI 91.3-96.1%), and PPV and NPV were 81.5% (95% CI 73.6-87.6%) and 89.4% (95% CI 86-92%) respectively. The sensitivity for detecting maculopathy in VistaView was 71.2% (95% CI 62.8-78.4%), while the specificity was 86.4% (82.6-89.4%). The PPV and NPV of detecting maculopathy were 63% (95% CI 54.9-70.5%) and 90.1% (95% CI 86.8-92.9%) respectively. For VistaView, the ICC of DR grades was 78% (95% CI, 75-82%) between the two graders and that of maculopathy grades was 66% (95% CI, 59-71%). The Cohen's kappa for retinopathy grades of VistaView images was 0.61 (95% CI, 0.55-0.67, p<0.001), while that for maculopathy grades was 0.49 (95% CI 0.42-0.57, p<0.001). For images from the Topcon desktop camera, the ICC of DR grades was 85% (95% CI, 83-87%), while that of maculopathy grades was 79% (95% CI, 75-82%). The Cohen's kappa for retinopathy grades of Topcon images was 0.68 (95% CI, 0.63-0.74, p<0.001), while that for maculopathy grades was 0.65 (95% CI, 0.58-0.72, p<0.001). The VistaView offers moderate diagnostic accuracy for DR screening and may be used as a screening tool in LMIC.

Fluorescence-based determination of tobramycin using a portable smartphone-based device

The study presents the development of a robust portable smartphone-based device for determining tobramycin in drugs and urine by a fluorescence-based method. As existing analytical methods for the determination of tobramycin often require complex equipment and time-consuming procedures, the proposed approach offers simplicity, portability and real-time monitoring capabilities. The spectrofluorimetric method is based on the reaction of tobramycin and fluorescamine in an alkaline medium. The measurement of analytical signals was enabled with a specially designed device integrating a 3D printed adapter, LEDs, a macro lens, an Arduino-based microcontroller, and asmartphone. The traditional spectrofluorimetry was used as a reference method. Preliminary and optimisation studies were conducted to select the most suitable experimental conditions (e.g. reagent concentration and reaction time) as well as instrumental parameters (e.g. selection of the appropriate RGB model component, ISO, and white balance). The performance of the method was validated, and then verified against conventional spectrofluorimetry, showing comparable accuracy and precision. The method implemented in a smartphone-based device showed a linear range of 0.10–1.00 mgL-1 with a detection limit of 0.03 mgL-1. Synthetic samples were tested to verify analytical usability, followed by analysis of pharmaceutical and urine samples. The method showed good precision (CV<3.4 %) and recovery values (92.3–114.1 %), consistent with spectrofluorimetric results (CV<5.9 %, recovery 92.3–119.8 %). Comparison with other methods highlighted the simplicity and efficiency of the developed approach. The research reveals that it is competitive with existing well-established methods. The proposed device offers reliable results with low reagent and sample consumption, making itsuitable for on-the-go analysis in non-laboratory conditions.

An all-in-one smartphone-assisted ratiometric fluorescent device for visual and quantitative detection of glutathione

The daily consumption of foods abundant in Glutathione (GSH) can be supplemented to maintain the homeostasis of GSH in human health and alleviate pathologies resulting from abnormal GSH levels. The fluorescence-based visual determination of GSH has gradually attracted the attention of researchers due to its robust performance and versatile implementation. However, the current GSH visual strategy primarily relies on variations in fluorescence intensity at a single emission wavelength, which poses challenges for naked-eye and portable readout, as well as distorted signals caused by complex matrix effects in real samples. Herein, a ratiometric fluorescence sensor based on carbon dots (CDs) combined with an all-in-one 3D-printed smartphone-based device was successfully developed for low-cost, visual and rapid detection of GSH without the need for an external excitation light source. The ratiometric fluorescent materials were synthesized by conjugating blue carbon dots (B-CDs) with yellow carbon dots (Y-CDs) through the utilization of selected Cu2+ ions. The resulting mechanism demonstrated that the coordination interaction between Cu2+ and residual aromatic amino groups in Y-CDs (Y-CDs-Cu2+) contributed to a newly emitted peak at 580 nm, thereby inducing fluorescence resonance energy transfer from B-CDs to Y-CDs-Cu2+. A linear correlation was found between GSH concentrations and R/B values in the range of 10–100 μM, with a limit of detection observed at 4.8 μM. By utilizing this portable device in combination with RGB analysis, the quantitative detection of GSH can be achieved even in complex food matrices such as tomatoes and grapes. The universality of this all-in-one device was further validated by pre-spraying CDs onto a paper strip for visual measurement of GSH. This work offers a portable, visual, and accessible approach to evaluating food safety and nutrition, thereby demonstrating significant economic value and holding profound implications for human health.

Hybrid nanoflower-based electrochemical lateral flow immunoassay for Escherichia coli O157 detection.

An electrochemical biosensor has been developedfor detection of Escherichia coli O157 by integrating lateral flow with screen-printed electrodes. The screen-printed electrodes were attached under the lateral flow detection line, and organic-inorganic nanoflowers prepared from E. coli O157-specific antibodies as an organic component were attached to the lateral flow detection line. In the presence of E. coli O157, an organic-inorganic nanoflower-E. coli O157-antimicrobial peptide-labelled ferrocene sandwich structure is formed on the lateral flow detection line. Differential pulse voltammetry is applied using a smartphone-based device to monitor ferrocene on the detection line. The resulting electrochemical biosensor could specifically detect E. coli O157 with a limit of detection of 25 colony-forming units mL-1. Through substitution of antibodies of organic components in organic-inorganic nanoflowers, biosensors have great potential for the detection of other pathogens in biomedical research and clinical diagnosis.

Colorimetric enzymatic rapid test for the determination of atropine in baby food using a smartphone.

A method for the enzymatic determination of atropine has been developed, which is based on a sequence of reactions involving (1) the hydrolysis of atropine to give tropine; (2) the enzymatic oxidation of tropine with NAD (catalysed by tropinone reductase); and (3) an indicator reaction, in which the NADH previously formed reduces the dye iodonitrotetrazolium chloride (INT) to a reddish species, the reaction catalysed by diaphorase. The method was first developed in solution (linear response range from 2.4 × 10-6M to 1.0 × 10-4M). It was then implemented in cellulose platforms to develop a rapid test where the determination is made by measuring the RGB coordinates of the platforms using a smartphone-based device. The device is based on the integrating sphere concept and contains a light source to avoid external illumination effects. The smartphone is controlled by an app that allows a calibration line to be generated and the atropine concentration to be quantified; moreover, since the app normalizes the CCD response of the smartphone, the results and calibrations obtained with different smartphones are similar and can be shared. Using the G coordinate, the results were shown to have a linear response with the concentration of atropine ranging from 1.2 × 10-5M to 3.0 × 10-4M with an RSD of 1.4% (n = 5). The method has been applied to the determination of atropine in baby food and buckwheat samples with good results.

Rapid and portable quantification of HIV RNA via a smartphone-enabled digital CRISPR device and deep learning

For the 29.8 million people in the world living with HIV/AIDS and receiving antiretroviral therapy, it is crucial to monitor their HIV viral loads. To this end, rapid and portable diagnostic tools that can quantify HIV RNA are critically needed. We report herein a rapid and quantitative digital CRISPR-assisted HIV RNA detection assay that has been implemented within a portable smartphone-based device as a potential solution. Specifically, we first developed a fluorescence-based reverse transcription recombinase polymerase amplification (RT-RPA)-CRISPR assay that can efficiently detect HIV RNA at 42 °C. We then implemented this assay within a commercial stamp-sized digital chip, where RNA molecules were quantified as strongly fluorescent digital reaction wells. The isothermal reaction condition and the strong fluorescence in the digital chip simplified the design of thermal and optical modules, allowing us to engineer a palm-size device measuring 70 × 115 × 80 mm and weighing less than 0.6 kg. We also capitalized the smartphone by developing a custom app to control the device, perform the digital assay, and capture fluorescence images throughout the assay using the smartphone's camera. Moreover, we trained and verified a deep learning-based algorithm for analyzing fluorescence images and identifying positive digital reaction wells with high accuracy. Using our smartphone-enabled digital CRISPR device, we successfully detected as low as 75 copies of HIV RNA in just 15 min, showing its potential toward monitoring of HIV viral loads and aiding the global effort to combat the HIV/AIDS epidemic.

Smartphone-based device for rapid and single-step detection of piRNA–651 using anti-DNA:RNA hybrid antibody and enzymatic signal amplification

P-element-induced wimpy testis (PIWI)-interacting RNAs (piRNAs/piRs) are a class of small noncoding RNAs that play a crucial role in regulating various biological processes, including carcinogenesis. One specific piRNA, piR–651, has been reported to be overexpressed in both human blood serum and solid cancer tissues, that can be used a viable biomarker in cancer diagnosis. Early diagnosis of cancer can help reduce the burden of the disease and improve survival rates. In the present work, we report for the first time a smartphone-based colorimetric biosensor for highly sensitive and specific detection of piR–651 thanks to an enzymatic signal amplification, which yielded high colorimetric intensities. Indeed, a heteroduplex DNA:RNA was formed in the presence of piR–651 with the capture DNA probe immobilized on the magnetic beads for easy magnetic separation. Then, a HRP tethered to anti-DNA:RNA (S9.6) was used to reveal the DNA-RNA heteroduplex formed by catalyzing the oxidation of TMB substrate into colorimetric TMBox, which absorbs at 630 nm. The absorbance is positively proportional to the piR–651 concentrations. On the other hand, the colorimetric product of the assay can be photographed with a smartphone camera and analyzed using ImageJ software. Using a smartphone and under optimal conditions, the biosensor responded linearly to the logarithm of piRNA–651 from 8 fM to 100 pM with a detection limit of 2.3 fM and discriminates against other piRNAs. It was also successfully applied to the determination of piRNA–651 levels in spiked human serum.

Smartphone-based device for point-of-care diagnostics of pulmonary inflammation using convolutional neural networks (CNNs)

In pulmonary inflammation diseases, like COVID-19, lung involvement and inflammation determine the treatment regime. Respiratory inflammation is typically arisen due to the cytokine storm and the leakage of the vessels for immune cells recruitment. Currently, such a situation is detected by the clinical judgment of a specialist or precisely by a chest CT scan. However, the lack of accessibility to the CT machines in many poor medical centers as well as its expensive service, demands more accessible methods for fast and cheap detection of lung inflammation. Here, we have introduced a novel method for tracing the inflammation and lung involvement in patients with pulmonary inflammation, such as COVID-19, by a simple electrolyte detection in their sputum samples. The presence of the electrolyte in the sputum sample results in the fern-like structures after air-drying. These fern patterns are different in the CT positive and negative cases that are detected by an AI application on a smartphone and using a low-cost and portable mini-microscope. Evaluating 160 patient-derived sputum sample images, this method demonstrated an interesting accuracy of 95%, as confirmed by CT-scan results. This finding suggests that the method has the potential to serve as a promising and reliable approach for recognizing lung inflammatory diseases, such as COVID-19.

A smartphone-based standalone fluorescence spectroscopy tool for cervical precancer diagnosis in clinical conditions.

Real-time prediction about the severity of noncommunicable diseases like cancers is a boon for early diagnosis and timely cure. Optical techniques due to their minimally invasive nature provide better alternatives in this context than the conventional techniques. The present study talks about a standalone, field portable smartphone-based device which can classify different grades of cervical cancer on the basis of the spectral differences captured in their intrinsic fluorescence spectra with the help of AI/ML technique. In this study, a total number of 75 patients and volunteers, from hospitals at different geographical locations of India, have been tested and classified with this device. A classification approach employing a hybrid mutual information long short-term memory model has been applied to categorize various subject groups, resulting in an average accuracy, specificity, and sensitivity of 96.56%, 96.76%, and 94.37%, respectively using 10-fold cross-validation. This exploratory study demonstrates the potential of combining smartphone-based technology with fluorescence spectroscopy and artificial intelligence as a diagnostic screening approach which could enhance the detection and screening of cervical cancer.

A smartphone-assisted fluorescent sensing platform for ochratoxin A using Mn-doped CsPbBr3 perovskite quantum dots embedded in the mesoporous silica as a ratiometric probe

Food sources are susceptible to contamination with ochratoxin A (OTA), which is a serious threat to human health. Thus, the construction of novel, simple sensing platforms for OTA monitoring is of utmost need. Manganese-doped lead halide perovskite quantum dots encapsulated with mesoporous SiO2 (Mn-CsPbBr3 QDs@SiO2) were prepared here and used as a ratiometric fluorescent probe for OTA. Mn-CsPbBr3 QDs, synthesized at room temperature, exhibit dual emission with maximum wavelengths of 440 and 570 nm and, when embedded in the SiO2 layer, produce a stable and robust photoluminescence signal. By adding OTA to the probe, emission at 440 nm increases while emission at 570 nm decreases, so a ratiometric response is obtained. Experimental variables affecting the probe signal were studied and optimized and the mechanism of sensing was discussed. This ratiometric sensor demonstrated excellent selectivity and low detection limit (4.1 ng/ml) as well as a wide linear range from 5.0 to 250 ng/ml for OTA. A simple portable smartphone-based device was also constructed and applied for the fluorescence assay. With different OTA concentrations, the multicolor transition from pink to blue under a UV lamp led to simple visual and smartphone-assisted sensing of OTA by using a color analyzing application. Satisfactory recoveries in black tea, coffee, moldy fig and flour samples confirmed the reliability of the assay. The accuracy of the probe was proved by comparison of the results with high-performance liquid chromatography (HPLC).

Supra-Quantum Dot Assemblies to Maximize Color-Based Multiplexed Fluorescence Detection with a Smartphone Camera.

Photoluminescence (PL) imaging and bioanalysis with smartphone-based devices are of growing interest for point-of-care/point-of-need diagnostics. Strategies for maximizing sensitivity have been explored in this context, but color multiplexing has been very limited, with its maximum level unexplored. Here, we evaluated color multiplexing with smartphone-based PL imaging by using supra-nanoparticle assemblies of quantum dots (supra-QDs). These materials were prepared as composite colors that were tailored to the red-green-blue (RGB) color space of smartphone cameras by coassembling different ratios of R-, G-, and B-emitting QDs on a silica nanoparticle scaffold. The supra-QDs were characterized and used to label cell-sized objects that were measured under flow with a smartphone-based device. Each color followed an approximately linear trajectory in the RGB space, and training of support vector machine models enabled color classification with overall accuracies ≥87% for 10-color multiplexing and better accuracies for fewer colors. Most misclassification occurred at low signal levels, such that establishing a nonclassifiable zone near the origin of RGB color space improved the overall 10-color classification accuracy to ≥94%. Similar improvements in accuracy with greater retention of data were possible with a probabilistic rather than a radial threshold. Simulations that were parameterized by experimental data suggested that ≥14-color multiplexing with accuracies ≥90% should be possible with an optimized supra-QD color set. This study is an important foundation for advancing RGB color-based multiplexing for imaging and analyses with smartphone cameras and related charge-coupled device and CMOS color image sensor technologies.

Multi-signal aptasensor for thrombin detection based on catalytically active gold nanoparticles and fluorescent silicon quantum dots.

A multi-signal aptasensor for thrombin determination isproposed based on catalytically active gold nanoparticles (AuNPs) and fluorescent silicon quantum dots (SiQDs). Yellow 4-Nitrophenol (4-NP) could be converted to colorless 4-Aminophenol (4-AP) by catalytically active aptamer-modified AuNPs (S1-AuNPs). The SiQDs emitted strong blue fluorescence at 455nm at the excitation wavelength of 367nm. When thrombin was absent, S1-AuNPs could catalytically reduce yellow 4-NP to colorless 4-AP. When thrombin was added, the aptamer could be transformed into a G-quadruplex structure, which masked the surface-active catalytic sites of AuNPs and restrained the reduction of 4-NP. Thus, the fluorescence of SiQDs was greatly quenched by 4-NP through the inner filter effect (IFE), and the solution color remained yellow. As the concentration of thrombin increased, the catalytic activity of S1-AuNPs decreased. The concentration of 4-NP that was converted to 4-AP declined and the unconverted 4-NP increased. In this process, the absorption peak of 4-NP at 400nm increased while the fluorescence emission of SiQDs at 455nm decreased. The linear ranges of the fluorometric and colorimetric aptasensor were 0.5-30nM and 0.3-30nM, respectively. The limits of detection (LOD) for the two modes were 0.15nM and 0.13nM. Furthermore, a portable sensing platform was constructed by combining the smartphone-based device with the software ImageJ for the determination of thrombin. With the advantages of cost-effectiveness, simplicity of operation and broad applicability, this aptasensor provided a new perspective for on-site determinationof thrombin in the clinical field.

Immunochromatographic assay integrated smartphone-based device for simultaneous detection of multiple mycotoxins using core-shell up-conversion nanoparticles

Universal contamination and synergistic toxicity of multiple mycotoxins in foodstuffs have become a challenge in food safety, posing a serious threat to human and animal health. Herein, we developed a multiple immunochromatography assay (mICA) integrating a smartphone device with core-shell up-conversion nanoparticles (UCNPs) for simultaneous detection of deoxynivalenol (DON), aflatoxin B1 (AFB1) and zearalenone (ZEN) in cereals. The limits of detection for DON, AFB1, and ZEN could be quickly obtained within 10 min, with values of 0.25 ng/mL, 0.05 ng/mL, and 0.1 ng/mL, respectively. Furthermore, the practicability and repeatability of the core-shell UCNPs-mICA were successfully evaluated by detecting the recoveries of DON, AFB1 and ZEN in corn and wheat under the optimal sample extraction. The results obtained by the smartphone-based UCNPs-mICA were consistent with those by high-performance liquid chromatography, demonstrating the advantage of being faster and more portable. Due to its high sensitivity, high specificity, low cost, and portability, the proposed core-shell UCNPs-mICA integrated with a smartphone-based device provides significant potential prospects in the rapid screening of mycotoxins.

Foldable low-cost point-of-care device for testing blood coagulation using smartphones

Cardiovascular diseases (CVDs) caused by thrombotic events are a significant global health concern, affecting millions of people worldwide. The international normalized ratio (INR) is the most widely used measure of coagulation status, and frequent testing is required to adjust blood-thinning drug dosage, requiring hospital visits and experts to perform the test. Here we present a low-cost and portable smartphone-based device for screening INR levels from whole blood samples at the point of care. Our device uses a 3D printed platform and light-emitting diode backlight modules to create a uniform optical environment, and its foldable design allows for easy transport. Our device also features an algorithm that allows users to acquire and process video of sample flow in a microfluidic channel on their smartphone, providing a cost-effective and convenient option for blood coagulation monitoring at the point of care. We tested the performance of our smartphone-based INR device using both commercially available control samples and clinical human blood samples, demonstrating high accuracy and reliability. Our device has the potential to improve patient outcomes by enabling more frequent monitoring and, as appropriate, dosage adjustments of blood-thinning drugs, providing an affordable and portable option for screening INR levels at the point of care.

Quantitative and Multiplexed Chopper-Based Time-Gated Imaging for Bioanalysis on a Smartphone.

Smartphones are emerging platforms for point-of-care diagnostics (POCDs), where the on-board camera is, for example, used to image fluorescence. Many laboratory instruments are capable of time-gated (TG) photoluminescence (PL) measurements─an analytical method leveraged by multiple commercial assay kits. When paired with long-lived PL emitters such as luminescent lanthanide complexes (LLCs), time-gating eliminates background from sample autofluorescence and many other sources. This capability is amenable to minimally processed samples and would thus be useful for POCDs on a smartphone-based platform. Here, we report a double-chopper design for TG PL imaging using a portable, 3D-printed, smartphone-based device. The rotation speed, dimensions, and overlap of the chopper blades and gaps set the timing parameters, with delay times on the order of hundreds of microseconds to milliseconds. The device was capable of quantitative TG imaging of PL from terbium(III) and europium(III) LLCs, including rejection of short-lived PL background from serum and tissue phantoms, spectral and temporal multiplexing, a model time-gated Förster resonance energy transfer (TG-FRET) assay, and imaging of cells. As the first smartphone-based demonstrations of these important analytical capabilities, this work is an important foundation for developing POCD methods based on TG PL imaging.

Visual detection of Fusarium temperatum by using CRISPR-Cas12a empowered LAMP assay coupled with AuNPs-based colorimetric reaction

Fusarium temperatum (F. temperatum) causes maize stalk rot disease, reducing grain yield and producing multiple harmful mycotoxins that threaten food safety and quality. However, current detection methods are limited by the requirement of well-trained personnel, complicated operations and expensive instruments. To address this challenge, gold nanoparticles (AuNPs)-based colorimetric assay using loop-mediated isothermal amplification (LAMP) coupled with CRISPR-Cas12a (Au-CRISPR) was tested for F. temperatum detection. The assay utilizes DNA-modified AuNPs as a colorimetric probe and the results can be readily observed by the naked eye. After optimization, the method can specifically detect as low as 100 copies/μL of target DNA or 10−8 ng/μL of extracted DNA from F. temperatum. The detection platform allows high-throughput testing by integrating microtiter plates and microplate reader. Furthermore, a portable smartphone-based device was developed to realize point of care (POC) detection of F. temperatum in resource-limited settings. This simple, inexpensive and sensitive detection platform has great potential for the applications in field detection.

Using a Smartphone-Based Colorimetric Device with Molecularly Imprinted Polymer for the Quantification of Tartrazine in Soda Drinks.

The present study reports the development and application of a rapid, low-cost in-situ method for the quantification of tartrazine in carbonated beverages using a smartphone-based colorimetric device with molecularly imprinted polymer (MIP). The MIP was synthesized using the free radical precipitation method with acrylamide (AC) as the functional monomer, N,N'-methylenebisacrylamide (NMBA) as the cross linker, and potassium persulfate (KPS) as radical initiator. The smartphone (RadesPhone)-operated rapid analysis device proposed in this study has dimensions of 10 × 10 × 15 cm and is illuminated internally by light emitting diode (LED) lights with intensity of 170 lux. The analytical methodology involved the use of a smartphone camera to capture images of MIP at various tartrazine concentrations, and the subsequent application of the Image-J software to calculate the red, green, blue (RGB) color values and hue, saturation, value (HSV) values from these images. A multivariate calibration analysis of tartrazine in the range of 0 to 30 mg/L was performed, and the optimum working range was determined to be 0 to 20 mg/L using five principal components and a limit of detection (LOD) of 1.2 mg/L was obtained. Repeatability analysis of tartrazine solutions with concentrations of 4, 8, and 15 mg/L (n = 10) showed a coefficient of variation (% RSD) of less than 6%. The proposed technique was applied to the analysis of five Peruvian soda drinks and the results were compared with the UHPLC reference method. The proposed technique showed a relative error between 6% and 16% and % RSD lower than 6.3%. The results of this study demonstrate that the smartphone-based device is a suitable analytical tool that offers an on-site, cost-effective, and rapid alternative for the quantification of tartrazine in soda drinks. This color analysis device can be used in other molecularly imprinted polymer systems and offers a wide range of possibilities for the detection and quantification of compounds in various industrial and environmental matrices that generate a color change in the MIP matrix.

CESSAT: A chemical additive-enhanced single-step accurate CRISPR/Cas13 testing system for field-deployable ultrasensitive detection and genotyping of SARS-CoV-2 variants of concern.

The continued emergence of SARS-CoV-2 variants of concern (VOCs) has raised great challenges for epidemic prevention and control. A rapid, sensitive, and on-site SARS-CoV-2 genotyping technique is urgently needed for individual diagnosis and routine surveillance. Here, a field-deployable ultrasensitive CRISPR-based diagnostics system, called Chemical additive-Enhanced Single-Step Accurate CRISPR/Cas13 Testing system (CESSAT), for simultaneous screening of SARS-CoV-2 and its five VOCs (Alpha, Beta, Gamma, Delta, and Omicron) within 40min was reported. In this system, a single-step reverse transcription recombinase polymerase amplification-CRISPR/Cas13a assay was incorporated with optimized extraction-free viral lysis and reagent lyophilization, which could eliminate complicated sample processing steps and rigorous reagent storage conditions. Remarkably, 10% glycine as a chemical additive could improve the assay sensitivity by 10 times, making the limit of detection as low as 1 copy/μL (5 copies/reaction). A compact optic fiber-integrated smartphone-based device was developed for sample lysis, assay incubation, fluorescence imaging, and result interpretation. CESSAT could specifically differentiate the synthetic pseudovirus of SARS-CoV-2 and its five VOCs. The genotyping results for 40 clinical samples were in 100% concordance with standard method. We believe this simple but efficient enhancement strategy can be widely incorporated with existing Cas13a-based assays, thus leading a substantial progress in the development and application of rapid, ultrasensitive, and accurate nucleic acid analysis technology.

Ratiometric upconversion-luminescence in-situ sampling aptasensing platform integrated with smartphone-based device for visual detection of 17β-estradiol

Rapid initial screening of health markers and food hazards are crucial indicators for ensuring human well-being. Hence, an upconversion-luminescence based aptasensing platform for the in-situ sampling of hazards has been proposed with portable equipment for point-of-care testing (POCT). The aptasensing platform consists of a polymethylmethacrylate needle and a paper-based microfluidic strip patterned with a sacrificial valve, paraffin barriers, and three independent detection zones. The detection zones were assembled with a luminescence resonance energy transfer system constructed by the core/shell/shell structure of upconversion nanoparticles (UCNPs) as the donor, SYBR Green Ⅰ as the acceptor with an aptamer bridge. The biosensing platform has been extended for 17β-estradiol to validate its feasibility in a dual-mode signal readout system based on smartphone imaging and spectrometer. Under the optimal conditions, good linear relationships were achieved based on images (0.05–200 ng/mL) and ratiometric spectra (0.02–200 ng/mL), respectively. Thus, the biosensing platform with portable equipment might provide an economic and viable route for POCT.

Design and application of a smartphone-based device for in vineyard determination of anthocyanins content in red grapes

The choice of the proper moment for harvesting is a crucial aspect in winemaking process, since the chemical attributes of grape berries strongly influence red wine quality. In particular, phenolic composition of red grapes plays a significant role in many sensory properties of wine related to color and taste. Anthocyanins are the most important phenolic compounds for red grapes: they accumulate in the grape skin during ripening, and they are responsible for the purple color of ripe berries. Routine analysis for the determination of grapes phenolic maturity includes chromatographic and spectroscopic techniques, that are time-consuming and expensive. In this work, we propose an innovative device conceived for the determination of grape phenolic maturity based on RGB images of grape berries acquired with a smartphone. The device has been designed to be used directly in the vineyard thanks to its small size and to the possibility of acquiring geolocated images of the berries under controlled lighting conditions. In this study, grape samples of three different varieties (Ancellotta, Lambrusco Salamino and Sangiovese) were collected at different harvest times from veraison to maturity and imaged by means of a common smartphone using the device. The RGB images were then converted into one-dimensional signals, named colourgrams, which codify the color properties of the images. The dataset of colourgrams was then used to calculate calibration models using Partial Least Squares (PLS) regression in order to relate color information with chemical parameters generally employed to evaluate grape phenolic maturity, such as total anthocyanins content and extractable anthocyanins content. The calibration models were implemented in a software interface that allows to acquire geolocated images of the grape samples, visualize the outcomes of the analysis, visualize maps and plots related to phenolic maturity, store data and share relevant information.