Portable high-throughput multimodal immunoassay platform for rapid on-site COVID-19 diagnostics.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as a causal agent of Coronavirus Disease 2019 (COVID-19) has led to the global pandemic. Though the real-time reverse transcription polymerase chain reaction (RT-PCR) acting as a gold-standard method has been widely used for COVID-19 diagnostics, it can hardly support rapid on-site applications or monitor the stage of disease development as well as to identify the infection and immune status of rehabilitation patients. To suit rapid on-site COVID-19 diagnostics under various application scenarios with an all-in-one device and simple detection reagents, we propose a high-throughput multimodal immunoassay platform with fluorescent, colorimetric, and chemiluminescent immunoassays on the same portable device and a multimodal reporter probe using quantum dot (QD) microspheres modified with horseradish peroxidase (HRP) coupled with goat anti-human IgG.

SARS-CoV-2 detection using quantum dot fluorescence immunochromatography combined with isothermal amplification and CRISPR/Cas13a.

The development of reliable, sensitive, and fast devices for the diagnosis of COVID-19 is of great importance in the pandemic of the new coronavirus. Here, we proposed a new principle of analysis based on a combination of reverse transcription and isothermal amplification of a fragment of the gene encoding the S protein of the SARS-CoV-2 and the CRISPR/Cas13a reaction for cleavage of the specific probe. As a result, the destroyed probe cannot be detected on an immunochromatographic strip using quantum fluorescent dots.

Quantum dot microsphere-based immunochromatography test strip enabled sensitive and quantitative on-site detections for multiple mycotoxins in grains.

In this work, we design a sensitive and quantitative on-site detecting solution for Aflatoxin B1 (AFB1), Ochratoxin A (OTA) and Zearalenone (ZEN) as often found in moldy grains and harmful to human health. Using quantum dot microsphere-based immunochromatography test strip, the proposed method can sensitively detect AFB1, OTA and ZEN in low detection limits of 0.01 ng/mL, 0.

Quantitative and Selective DNA Detection with Portable Personal Glucose Meter Using Loop-Based DNA Competitive Hybridization Strategy.

A portable, quantitative, and selective DNA detection biosensor, based on a loop-based DNA competitive hybridization assay and a personal glucose meter (PGM), is an advanced strategy for one-step target DNA recognition and signal reporter generation. In the presence of target DNA, the invertase-DNA conjugates are released due to the competitive binding of target DNA and collected with the help of a magnet subsequently. The released invertase-DNA could catalyze the hydrolysis of sucrose into glucose with millions of turnovers which is target concentration dependent.

Rapid and ultra-sensitive detection of African swine fever virus antibody on site using QDM based-ASFV immunosensor (QAIS).

African swine fever (ASF) is a swine viral disease that could cause highly contagious and extremely high mortality, causing huge economic losses to the pig industry. As there is currently no vaccine and effective treatment methods. Therefore, early monitoring is one of the most important solutions to prevent and control ASF.

Amplification-free smartphone-based attomolar HBV detection.

Classical gold standard HBV detection relies on expensive devices and complicated procedures, thus is always restricted in large-scale hospitals and centers for disease control and prevention. To extend HBV detection to primary clinics especially in underdeveloped areas, we design amplification-free smartphone-based attomolar HBV detecting technique based on single molecule sensing. Verified by synthesized HBV target DNA, this technique reaches a detection limit at attomolar concentration (100 aM); and verified by 110 clinical samples, it also reaches a rather high sensitivity of 10 copy/mL (≈2000 IU/mL) with a high accuracy of 93.

Sensitive antibody fluorescence immunosorbent assay (SAFIA) for rapid on-site detection on avian influenza virus H9N2 antibody.

Avian influenza virus (AIV) is a serious zoonotic disease causing severe damages to both poultry industry and human health. To rapidly detect AIV on-site with high sensitivity and accuracy, we design sensitive antibody fluorescence immunosorbent assay (SAFIA) on AIV H9N2 antibody. In SAFIA, hemagglutinin (HA1) protein coated sample chamber specifically binds targets but remarkably reduces non-specific absorption; Protein L coated polystyrene microsphere captures target through secondary antibody to significantly amplify the fluorescence signal; and a portable fluorescence counter automatically measures the fluorescence spot density for AIV H9N2 antibody detection.

Dynamically probing ATP-dependent RNA helicase A-assisted RNA structure conversion using single molecule fluorescence resonance energy transfer.

RNA helicase A (RHA) as a member of DExH-box subgroup of helicase superfamily II, participates in diverse biological processes involved in RNA metabolism in organisms, and these RNA-mediated biological processes rely on RNA structure conversion. However, how RHA regulate the RNA structure conversion was still unknown. In order to unveil the mechanism of RNA structure conversion mediated by RHA, single molecule fluorescence resonance energy transfer was adopted to in our assay, and substrates RNA were from internal ribosome entry site of foot-and-mouth disease virus genome.

Dynamic Dissection of the Endocytosis of Porcine Epidemic Diarrhea Coronavirus Cooperatively Mediated by Clathrin and Caveolae as Visualized by Single-Virus Tracking.

Coronaviruses (CoVs) have caused severe diseases in humans and animals. Endocytic pathways, such as clathrin-mediated endocytosis (CME) and caveolae-mediated endocytosis (CavME), play an important role for CoVs to penetrate the cell membrane barrier. In this study, a novel CoV entry manner is unraveled in which clathrin and caveolae can cooperatively mediate endocytosis of porcine epidemic diarrhea coronavirus (PEDV).

Dynamic Dissection of Dynein and Kinesin-1 Cooperatively Mediated Intercellular Transport of Porcine Epidemic Diarrhea Coronavirus along Microtubule Using Single Virus Tracking.

It is now clear that the intercellular transport on microtubules by dynein and kinesin-1 motors has an important role in the replication and spread of many viruses. Porcine epidemic diarrhea virus (PEDV) is an enveloped, single-stranded RNA virus of the Coronavirus family, which can infect swine of all ages and cause severe economic losses in the swine industry. Elucidating the molecular mechanisms of the intercellular transport of PEDV through microtubule, dynein and kinesin-1 will be crucial for understanding its pathogenesis.

Quantitative ciprofloxacin on-site rapid detections using quantum dot microsphere based immunochromatographic test strips.

The ciprofloxacin (CIP) abuse has caused many problems threatening to human health. Here, we design the quantum dot microsphere (QDM) based immunochromatographic quantitative CIP test strip: when the sample under detection contains CIP, the QDM-monoclonal antibody (mAb) probes bound with the CIP and cannot be captured by CIP-bovine serum albumin (BSA) conjugation dispersed on the T lines, reducing the fluorescence intensities. These test strips can provide a low detection limit of 0.

Quantitative protein detection using single molecule imaging enzyme-linked immunosorbent assay (iELISA).

Protein detection is a key step in molecular biology research and is required for pathogen and protein marker testing for disease diagnostics. Here, single molecule imaging enzyme-linked immunosorbent assay (iELISA) is proposed to quantitatively measure the porcine circovirus type 2 (PCV2) Cap protein. The monoclonal antibody against PCV2 Cap protein indirectly immobilized on a polyethylene glycol (PEG) passivated slide by biotin-streptavidin interaction is used to capture the PCV2 Cap protein, and the PCV2 Cap protein can be detected in single molecule level according to the fluorescein isothiocyanate (FITC)-labeled secondary antibody using total internal reflection fluorescence microscopy.

Measurements on ATP induced cellular fluctuations using real-time dual view transport of intensity phase microscopy.

Dual view transport of intensity phase microscopy is adopted to quantitatively study the regulation of adenosine triphosphate (ATP) on cellular mechanics. It extracts cell phases in real time from simultaneously captured under- and over-focus images. By computing the root-mean-square phase and correlation time, it is found that the cellular fluctuation amplitude and speed increased with ATP compared to those with ATP depletion.

On-site quantitative Hg measurements based on selective and sensitive fluorescence biosensor and miniaturized smartphone fluorescence microscope.

Mercury is a bio-accumulative and toxic pollutant causing severe damages to human health and environment. Since Hg is the most stable form of mercury, selective and sensitive Hg detection is required. Though classical approaches can realize accurate Hg detection, the complicated instruments and the time-consuming operations inevitably limit their on-site applications.

Handheld Inkjet Printing Paper Chip Based Smart Tetracycline Detector.

Tetracycline is widely used as medicine for disease treatments and additives in animal feeding. Unfortunately, the abuse of tetracycline inevitably causes tetracycline residue in animal-origin foods. Though classical methods can detect tetracycline in high sensitivity and precision, they often rely on huge and expensive setups as well as complicated and time-consuming operations, limiting their applications in rapid and on-site detection.

Substrate Determinants for Unwinding Activity of the DExH/D-Box Protein RNA Helicase A.

RNA helicase A (RHA) as a member of the DExH/D-box subgroup of helicase superfamily II is involved in virtually all aspects of RNA metabolism. It exhibits robust RNA helicase activity in vitro. However, little is known about the molecular and physical determinants for RHA substrate recognition and RHA translocation along the nucleic acids.

A pH-dependent Antibacterial Peptide Release Nano-system Blocks Tumor Growth in vivo without Toxicity.

In this study, we designed a nano-system where a novel antibacterial peptide RGD-hylin a1 with reduced hemolysis than the commonly studied melittin was loaded onto mesoporous silica (HMS). We found out that the designed nano-system, RGD-hylin a1-HMS, released RGD-hylin a1 in a pH-dependent manner. It caused apoptosis of cancer cells at low dosage of the antibacterial peptide at pH = 5.

A label-free and self-assembled electrochemical biosensor for highly sensitive detection of cyclic diguanylate monophosphate (c-di-GMP) based on RNA riboswitch.

Cyclic diguanylate monophosphate (c-di-GMP) is an important second messenger that regulates a variety of complex physiological processes involved in motility, virulence, biofilm formation and cell cycle progression in several bacteria. Herein we report a simple label-free and self-assembled RNA riboswitch-based biosensor for sensitive and selective detection of c-di-GMP. The detectable concentration range of c-di-GMP is from 50 nM to 1 μM with a detection limit of 50 nM.