Ninghui Duan

Bio: Ninghui Duan is an academic researcher from Tianjin University of Science and Technology. The author has contributed to research in topics: Fluorescence & Chemistry. The author has co-authored 1 publications.

Ultrasensitive pathogenic bacteria detection by a smartphone-read G-quadruplex-based CRISPR-Cas12a bioassay

Abstract: Foodborne diseases, caused by pathogenic bacteria, severely threaten global human health and cause a financial burden. Rapid, sensitive and on-site detection of pathogenic bacteria is significant. The existing methods have different defects, such as time-consuming and inconvenient. In this study, we developed a G-quadruplex-based CRISPR-Cas12a bioassay for pathogenic bacteria detection with high sensitivity and visualization capability. Salmonella was used as the detection model. Simply, the amplicons of Salmonella specific invA gene activated the trans-cleavage activity of Cas12a and triggered CRISPR-Cas12a based indiscriminate degradation of single-stranded DNAs (ssDNAs). The ssDNAs were designed with the guanine-rich sequence and formed a stable G-quadruplex DNAzyme by adding K+. This DNAzyme could catalyze the TMB-H2O2 reaction in the presence of hemin, leading to an increase in absorbance at 454 nm and a color change. This change can be readily differentiated by the naked eyes as well as a smartphone with a Color Picker App. With this strategy, the limit of detection (LOD) for Salmonella was 1 CFU/mL with no cross-reactivity. A linear relationship (R2 = 0.993) between the absorbance and the concentration of Salmonella was obtained. Furthermore, G-quadruplex-based CRISPR-Cas12a bioassay was successfully applied for sensing Salmonella in real food samples. This work not only expands the reach of CRISPR-Cas based biosensing but also provides a novel pathogenic bacteria detection method with high sensitivity, specificity and on-site capability.

Research Progress on Multifunctional Fluorescent Probes for Biological Imaging, Food and Environmental Detection.

Abstract: There has been rapid progress in the development of fast, sensitive, cheap and low-cytotoxicity micro-molecule fluorescent probes for application in various fields, including disease diagnosis, food safety and environmental safety. As an analytical tool, dual-function fluorescent probes with dual-emission responses have attracted considerable attention due to their cost-effectiveness and efficiency over single-function sensors. This review primarily describes research progress on multifunctional probes in terms of the reaction type and coordination type, as well as the general design principles of probes. The analytes include reactive oxygen species (ROS), reactive sulfur species (RSS), harmful cations and anions, etc. Multifunctional probes for food, medical and environmental applications are listed for future research. To improve the development of rapid detection methods, trends and strategies in the development of multifunctional fluorescent probes are also discussed.

Application of a luminous intensity variation fluorescent probe for the detection of ferric ions.

Abstract: A luminous intensity variation fluorescent probe (Probe 1) for the detection of ferric ion was developed. The quantitative range of Fe3+ content detected was 0 to 600 μM with the LOD at 0.76 μM. Further, after 20 minutes of Fe3+ addition, the intensity of luminescence of Probe 1 solution gradually decreased with increased Fe3+ concentration. In addition, the B and G values of these images showed a linear relationship with Fe3+ concentration (0-500 μM). Probe 1 was successfully used for the rapid determination of Fe3+ concentration in real samples. This study demonstrates that Probe 1 is an excellent tool for the rapid determination of Fe3+ content in real samples using a smart phone without professional equipment.

A novel fluorescent probe for the detection of water content in organic solvents and the distinguish between deuterated and non deuterated reagents.

Abstract: A novel D-π-A type fluorescent probe (probe 1) was developed for water content detection in organic solvents. By analyzing the relationship between fluorescence and water content, the probe was successfully applied to determine trace water content in THF, ethyl acetate, 2-butanone, acetone, DMF, and acetonitrile. High water contents in THF and ethyl acetate were associated with a gradual color change from yellowish green to earthy yellow. The R/G value had a linear relationship with the water content in THF and ethyl acetate. There was a linear relationship between the R/B value and water content in 2-butanone and acetone. Furthermore, probe 1 could be used for human serum albumin (HSA) detection. Unexpectedly, the probe 1 has different color response in deuterated and non deuterated solvents, and has different fluorescence intensity and fluorescence emission wavelength. The probe 1 is rare tool that can distinguish between deuterated and non deuterated reagents.

CRISPR/Cas12a-based technology: A powerful tool for biosensing in food safety

Abstract: In the context of the current pandemic caused by the novel coronavirus, molecular detection is not limited to the clinical laboratory, but also faces the challenge of the complex and variable real-time detection fields. A series of novel coronavirus events were detected in the process of food cold chain packaging and transportation, making the application of molecular diagnosis in food processing, packaging, transportation, and other links urgent. There is an urgent need for a rapid detection technology that can adapt to the diversity and complexity of food safety. This review introduces a new molecular diagnostic technology-biosensor analysis technology based on CRISPR-Cas12a. Systematic clarification of its development process and detection principles. It summarizes and systematically organizes its applications in viruses, food-borne pathogenic bacteria, small molecule detection, etc. In the past four years, which provides a brand-new and comprehensive solution for food detection. Finally, this article puts forward the challenges and the prospects for food safety. The novel coronavirus hazards infiltrated every step of the food industry, from processing to packaging to transportation. The biosensor analytical technology based on CRISPR-Cas12a has great potential in the qualitative and quantitative analysis of infectious pathogens. CRISPR-Cas12a can effectively identify the presence of the specific nucleic acid targets and the small changes in sequences, which is particularly important for nucleic acid identification and pathogen detection. In addition, the CRISPR-Cas12a method can be adjusted and reconfigured within days to detect other viruses, providing equipment for nucleic acid diagnostics in the field of food safety. The future work will focus on the development of portable microfluidic devices for multiple detection. Shao et al. employed physical separation methods to separate Cas proteins in different microfluidic channels to achieve multiple detection, and each channel simultaneously detected different targets by adding crRNA with different spacer sequences. Although CRISPR-Cas12a technology has outstanding advantages in detection, there are several technical barriers in the transformation from emerging technologies to practical applications. The newly developed CRISPR-Cas12a-based applications and methods promote the development of numerous diagnostic and detection solutions, and have great potential in medical diagnosis, environmental monitoring, and especially food detection.

CRISPR-Cas-based detection for food safety problems: Current status, challenges, and opportunities.

Abstract: Food safety is one of the biggest public issues occurring around the world. Microbiological, chemical, and physical hazards can lead to food safety issues, which may occur at all stages of the supply chain. In order to tackle food safety issues and safeguard consumer health, rapid, accurate, specific, and field-deployable detection methods meeting diverse requirements are one of the imperative measures for food safety assurance. CRISPR-Cas system, a newly emerging technology, has been successfully repurposed in biosensing and has demonstrated huge potential to establish conceptually novel detection methods with high sensitivity and specificity. This review focuses on CRISPR-Cas-based detection and its current status and huge potential specifically for food safety inspection. We firstly illustrate the pending problems in food safety and summarize the popular detection methods. We then describe the potential applications of CRISPR-Cas-based detection in food safety inspection. Finally, the challenges and futuristic opportunities are proposed and discussed. Generally speaking, the current food safety detection methods are still unsatisfactory in some ways such as being time-consuming, displaying unmet sensitivity and specificity standards, and there is a comparative paucity of multiplexed testing and POCT. Recent studies have shown that CRISPR-Cas-based biosensing is an innovative and fast-expanding technology, which could make up for the shortcomings of the existing methods or even replace them. To sum up, the implementation of CRISPR-Cas and the integration of CRISPR-Cas with other techniques is promising and desirable, which is expected to provide "customized" and "smart" detection methods for food safety inspection in the coming future.

Metal nanoclusters combined with CRISPR-Cas12a for hepatitis B virus DNA detection

Abstract: Since hepatitis B virus (HBV) infection can cause chronic viral hepatitis, increase the risk of liver fibrosis and cirrhosis, and ultimately result in hepatoma, it is of great significance to explore convenient, rapid, and sensitive diagnostic strategies for HBV DNA detection. In this study, we developed a novel and sensitive fluorescent biosensor for HBV detection based on the sensing system consisting of CRISPR-Cas12a enzymes and metal nanoclusters as the luminescent nanoprobes, involving gold nanoclusters (AuNCs), silver nanoclusters (AgNCs), and copper nanoclusters (CuNCs). The DNA probes could effectively be applied as the template for the preparation of fluorescent metal nanoclusters. In the presence of the HBV target, the trans-cleavage capability of Cas12a was able to be initiated to degrade DNA probes, which brought about the inhibition of metal nanoclusters formation, thereby giving minimal fluorescence signals. In comparison with AuNCs and AgNCs, the CuNCs-based nanosensor exhibited much higher sensitivity. In addition, the fluorescence response of CuNCs to HBV detection was significantly faster, which could be completed within 25 min without the requirements of sophisticated equipment or harsh reaction conditions. Moreover, the practical application of this analysis method was also demonstrated to detect HBV DNA target in human serum samples with satisfactory recovery, which was promising for simple, rapid, sensitive, and label-free HBV DNA bioanalysis. • The biosensor for HBV DNA detection consisting of CRISPR-Cas12a and metal nanoclusters is developed. • Different metal (gold, silver, and copper) nanoclusters have been applied as the luminescent nanoprobes. • The sensing platform allows rapid DNA detection within 25 min with high sensitivity and selectivity.

CRISPR/Cas Systems‐Inspired Nano/Biosensors for Detecting Infectious Viruses and Pathogenic Bacteria

Abstract: Infectious pathogens cause severe human illnesses and great deaths per year worldwide. Rapid, sensitive, and accurate detection of pathogens is of great importance for preventing infectious diseases caused by pathogens and optimizing medical healthcare systems. Inspired by a microbial defense system (i.e., CRISPR/ CRISPR-associated proteins (Cas) system, an adaptive immune system for protecting microorganisms from being attacked by invading species), a great many new biosensors have been successfully developed and widely applied in the detection of infectious viruses and pathogenic bacteria. Moreover, advanced nanotechnologies have also been integrated into these biosensors to improve their detection stability, sensitivity, and accuracy. In this review, the recent advance in CRISPR/Cas systems-based nano/biosensors and their applications in the detection of infectious viruses and pathogenic bacteria are comprehensively reviewed. First of all, the categories and working principles of CRISPR/Cas systems for establishing the nano/biosensors are simply introduced. Then, the design and construction of CRISPR/Cas systems-based nano/biosensors are comprehensively discussed. In the end, attentions are focused on the applications of CRISPR/Cas systems-based nano/biosensors in the detection of infectious viruses and pathogenic bacteria. Impressively, the remaining opportunities and challenges for the further design and development of CRISPR/Cas system-based nano/biosensors and their promising applications are proposed.