All-in-one microfluidic chip for 30-min quantitative point-of-care-testing of nucleic acids

Nucleic acid testing (NAT) is directly oriented to determining the genetic material of pathogens and is characterized by its high sensitivity and specificity, which are indispensable qualities in disease diagnosis. However, standard laboratory NAT methods require joint testing by highly trained inspectors using multiple instruments in professional laboratories. The entire process requires many manual steps, and the total testing time may range from 3 to 5h, indicating that these methods cannot be used to realize the demands of on-site rapid testing. In this study, we propose a microfluidic chip for the on-site and rapid detection of nucleic acids. We utilize dynamic sealing, ultrasound, and advanced control methods and integrate the entire process of reagent pre-storage, extraction, Real-time Quantitative polymerase chain reaction (qPCR), and fluorescence detection. The sensitivity of this system is in line with current clinical standards, and the nucleic acid quantification process is completed fully automated within 30min. Compared with conventional microfluidic chips, the proposed system has the advantages of high integration, low cost, and it may be produced at a high volume. Moreover, it can be used in a wide range of screening cases in the context of the COVID-19 pandemic and exhibits broad clinical application prospects.

Effect of Sini Decoction plus Ginseng on COVID-19 based on network pharmacological analysis

Objective: To explore the effect of Sini Decoction plus Ginseng on COVID-19 based on network pharmacological analysis.

Development of amplification system for point-of-care test of nucleic acid.

Nucleic acid testing (NAT) has been widely used in many fields such as medical diagnosis, food safety testing and forensic identification. However, it can only be carried out in professional laboratory because the test process is complicated and rigorous. In this paper, a nucleic acid amplification system based on polymerase chain reaction (PCR) was developed to meet the requirements of point-of-care testing (POCT) for nucleic acids. Firstly, the mechanical structure and electronic control system were designed and constructed. Secondly, an integral separation PID algorithm for temperature control and an intelligent temperature compensation method based on support vector regression (SVR) were proposed. Finally, temperature measurement and biological experiments were performed to prove the stability and availability of the nucleic acid amplification system. The results showed that the system achieved a rapid temperature change velocity of 4.5 °C/s, and the steady-state error was within ± 0.5 °C. The nucleic acids in samples of different concentrations were well amplified, the system can be used for quantitative detection of nucleic acid with the help of a fluorescence detection system, and has higher sensitivity than Tianlong PCR instrument.

Preliminary study on potence of Xinjia Xiangru decoction against COVID-19 based on network pharmacology and molecular docking technology

Objective: To explore the active ingredients, targets, pathways and molecular mechanism of Xinjia Xiangru Decoction in the possible treatment of new coronavirus pneumonia (COVID-19) through network pharmacology and molecular docking technology.

Transferable, easy-to-use and room-temperature-storable PCR mixes for microfluidic molecular diagnostics.

As the outbreak of coronavirus disease 2019 (COVID-19), on-site molecular diagnosis is becoming increasingly important. In this study, a freeze-drying method was introduced for PCR reagents to meet the requirements of microfluidic molecular diagnosis. Using this method, PCR components were pre-mixed and freeze-dried as a bead, which could be transferred into microfluidic chips easily. As this bead only required reconstitution in water, operational steps of PCR were simplified, pipetting errors and errors associated with improper handling of wet reagents could also be reduced. In addition, 19 PCR mixes for different targets (including both RNA and DNA) detection were stable when stored at room temperature (18-25 °C) for 1-2 years and may be stored longer as activity monitoring remains ongoing. To shorten the stability testing time, accelerated stability testing at higher temperatures was proposed. The evaluation periods of the freeze-dried PCR mixes were shortened to less than one month when stored at 56 °C and 80 °C. When attempts were further tried to predict the shelf lives for freeze-dried PCR mixes, our findings challenged the classic view of the Q10 method as a prediction model for freeze-dried PCR mixes and confirmed for the first time that this prediction was influenced by different factors at varying degrees. These studies and findings are important for the development of molecular diagnosis at both central laboratories and resource-limited areas.

Room-temperature-storable PCR mixes for SARS-CoV-2 detection.

OBJECTIVES: A novel coronavirus (severe acute respiratory syndrome coronavirus 2, SARS-CoV-2) emerged in late 2019, causing an outbreak of pneumonia [coronavirus disease 2019 (COVID-19)] globally. Although the use of ready-made reaction mixes can enable more rapid PCR-based diagnosis of COVID-19, the need to transport and store these mixes at low temperatures presents challenges to already overburdened logistics networks. METHODS: Here, we present an optimized freeze-drying procedure that allows SARS-CoV-2 PCR mixes to be transported and stored at ambient temperatures, without loss of activity. Additive-supplemented PCR mixes were freeze-dried. The residual moisture of the freeze-dried PCR mixes was measured by Karl-Fischer titration. RESULTS: We found that the freeze-dried PCR mixes with ~1.2% residual moisture are optimal for storage, transport, and reconstitution. The sensitivity, specificity, and repeatability of the freeze-dried reagents were similar to those of freshly prepared, wet reagents. The freeze-dried mixes retained activity at room temperature (18 ~ 25 °C) for 28 days, and for 14 and 10 days when stored at 37 °C and 56 °C, respectively. CONCLUSION: The uptake of this approach will ease logistical challenges faced by transport networks and make more cold storage space available at diagnosis and hospital laboratories.