Platinum-Decorated Gold Nanoparticle-Based Microfluidic Chip Immunoassay for Ultrasensitive Colorimetric Detection of SARS-CoV-2 Nucleocapsid Protein.

Gold nanoparticle-based point-of-care tests (POCT) are one of the most widely used diagnostic tools for SARS-CoV-2 screening. However, the limitation of their insufficient sensitivity often leads to false negative results in early disease diagnostics. The ongoing pandemic of COVID-19 makes diagnostic tools that are more accurate, sensitive, simple, and affordable in high demand. In this work, we develop a platinum-decorated gold nanoparticle (Au@Pt NP)-based microfluidic chip immunoassay with a sensitivity surpassing that of paper-based detection of nucleocapsid (N) protein, one of the most conserved biomarkers of COVID-19. The synthesized Au@Pt NPs show high stability and catalytic activity in complex environments. The catalytic amplification of Au@Pt NPs enables naked-eye detection of N protein in the low femtogram range (ca. 0.1 pg/mL) and the detection of throat swab samples in under 40 min. This microfluidic chip immunoassay is easy for operation and readout without instrument assistance, making it more suitable for on-site detection and future pathogen surveillance.

Ultrasensitive Detection of COVID-19 Virus N Protein Based on p-Toluenesulfonyl Modified Fluorescent Microspheres Immunoassay.

The pandemic of new coronary pneumonia caused by the COVID-19 virus continues to ravage the world. Large-scale population testing is the key to controlling infection and related mortality worldwide. Lateral flow immunochromatographic assay (LFIA) is fast, inexpensive, simple to operate, and easy to carry, very suitable for detection sites. This study developed a COVID-19 N protein detect strip based on p-toluenesulfonyl modified rare earth fluorescent microspheres. The p-toluenesulfonyl-activated nanomaterials provide reactive sulfonyl esters to covalently attach antibodies or other ligands containing primary amino or sulfhydryl groups to the nanomaterial surface. Antibodies are immobilized on these nanomaterials through the Fc region, which ensures optimal orientation of the antibody, thereby increasing the capture rate of the target analyte. The use of buffers with high ionic strength can promote hydrophobic binding; in addition, higher pH could promote the reactivity of the tosyl group. The detection limit of the prepared COVID-19 N protein strips can reach 0.01 ng/mL, so it has great application potential in large-scale population screening.

Ultrasensitive Detection of COVID-19 Virus N Protein Based on p-Toluenesulfonyl Modified Fluorescent Microspheres Immunoassay (preprint)

The pandemic of new coronary pneumonia caused by the COVID-19 virus continues to ravage the world. Large-scale population testing is the key to controlling infection and related mortality worldwide. Lateral flow immunochromatographic assay (LFIA) is fast, inexpensive, simple to operate, and easy to carry, very suitable for detection sites. This study developed a COVID-19 N protein detect strip based on p-toluenesulfonyl modified rare earth fluorescent microspheres. The p-toluenesulfonyl-activated nanomaterials provide reactive sulfonyl esters to covalently attach antibodies or other ligands containing primary amino or sulfhydryl groups to the nanomaterial surface. Antibodies are immobilized on these nanomaterials through the Fc region, which ensures optimal orientation of the antibody, thereby increasing the capture rate of the target analyte. The use of buffers with high ionic strength can promote hydrophobic binding, in addition, higher pH could promote the reactivity of the tosyl group. The detection limit of the prepared COVID-19 N protein strips can reach 0.01ng/mL so it has great application potential in large-scale population screening.

Distinct mutations and lineages of SARS-CoV-2 virus in the early phase of COVID-19 pandemic and subsequent 1-year global expansion.

A novel coronavirus, SARS-CoV-2, has caused over 274 million cases and over 5.3 million deaths worldwide since it occurred in December 2019 in Wuhan, China. Here we conceptualized the temporospatial evolutionary and expansion dynamics of SARS-CoV-2 by taking a series of the cross-sectional view of viral genomes from early outbreak in January 2020 in Wuhan to the early phase of global ignition in early April, and finally to the subsequent global expansion by late December 2020. Based on the phylogenetic analysis of the early patients in Wuhan, Wuhan/WH04/2020 is supposed to be a more appropriate reference genome of SARS-CoV-2, instead of the first sequenced genome Wuhan-Hu-1. By scrutinizing the cases from the very early outbreak, we found a viral genotype from the Seafood Market in Wuhan featured with two concurrent mutations (i.e., M type) had become the overwhelmingly dominant genotype (95.3%) of the pandemic 1 year later. By analyzing 4013 SARS-CoV-2 genomes from different continents by early April, we were able to interrogate the viral genomic composition dynamics of the initial phase of global ignition over a time span of 14 weeks. Eleven major viral genotypes with unique geographic distributions were also identified. WE1 type, a descendant of M and predominantly witnessed in western Europe, consisted of half of all the cases (50.2%) at the time. The mutations of major genotypes at the same hierarchical level were mutually exclusive, which implies that various genotypes bearing the specific mutations were propagated during human-to-human transmission, not by accumulating hot-spot mutations during the replication of individual viral genomes. As the pandemic was unfolding, we also used the same approach to analyze 261 323 SARS-CoV-2 genomes from the world since the outbreak in Wuhan (i.e., including all the publicly available viral genomes) to recapitulate our findings over 1-year time span. By December 25, 2020, 95.3% of global cases were M type and 93.0% of M-type cases were WE1. In fact, at present all the five variants of concern (VOC) are the descendants of WE1 type. This study demonstrates that viral genotypes can be utilized as molecular barcodes in combination with epidemiologic data to monitor the spreading routes of the pandemic and evaluate the effectiveness of control measures. Moreover, the dynamics of viral mutational spectrum in the study may help the early identification of new strains in patients to reduce further spread of infection, guide the development of molecular diagnosis and vaccines against COVID-19, and help assess their accuracy and efficacy in real world at real time.

Distinct mutations and lineages of SARS-CoV-2 virus in the early phase of COVID-19 pandemic and subsequent global expansion (preprint)

A novel coronavirus, SARS-CoV-2, has caused over 85 million cases and over 1.8 million deaths worldwide since it occurred twelve months ago in Wuhan, China. Here we conceptualized the time-series evolutionary and expansion dynamics of SARS-CoV-2 by taking a series of cross-sectional view of viral genomes from early outbreak in January in Wuhan to early phase of global ignition in early April, and finally to the subsequent global expansion by late December 2020. By scrutinizing cases from early outbreak, we found a viral genotype from the Seafood Market in Wuhan featured with two concurrent mutations has become the overwhelmingly dominant genotype (95.3%) of the pandemic. By analyzing 4,013 full-length SARS-CoV-2 genomes from different continents by early April, we were able to visualize the genomic diversity over a 14-week timespan since the outbreak in Wuhan. 2,954 unique nucleotide substitutions were identified with 31 of the 4,013 genomes remaining as ancestral type, and 952 (32.2%) mutations recurred in more than one genome. 11 major viral genotypes with unique geographic distributions were identified. As the pandemic has been unfolding for more than one year, we also used the same approach to analyze 261,323 full-length SARS-CoV-2 genomes from the world since the outbreak in Wuhan (i.e. including all the available viral genomes in the GISAID database as of 25 December 2020) in order to recapitulate our findings in a real-time fashion and to present a full catalogue of SARS-CoV-2 mutations. We demonstrated the viral genotypic dynamics from different geographic locations over one-year timespan reveal transmission routes and indicate subsequent expansion. This study, to our knowledge, is heretofore the largest and most comprehensive genomic study of SARS-CoV-2. It indicates the viral genotypes can be utilized as molecular barcodes in combination with epidemiologic data to monitor the spreading routes of the pandemic and evaluate the effectiveness of control measures. Moreover, the dynamics of viral mutational spectrum in the study may help the early identification of new strains in patients to reduce further spread of infection, and guide the development of molecular diagnosis and vaccines against COVID-19, and last but not the least help assess their accuracy and efficacy.    

Distinct mutations and lineages of SARS-CoV-2 virus in the early phase of COVID-19 global pandemic and subsequent global expansion (preprint)

A novel coronavirus, SARS-CoV-2, has caused over 8538 million cases and over 1.8 1 million deaths worldwide since it occurred twelve months ago in Wuhan, China. Here we first analyzed 4,013 full-length SARS-CoV-2 genomes from different continents over a 14-week timespan since the outbreak in Wuhan, China. 2,954 unique nucleotide substitutions were identified with 31 of the 4,013 genomes remaining as ancestral type, and 952 (32.2%) mutations recurred in more than one genome. A viral genotype from the Seafood Market in Wuhan featured with two concurrent mutations was the dominant genotype (80.9%) of the pandemic. We also identified unique genotypic compositions from different geographic locations, and time-series viral genotypic dynamics in the early phase that reveal transmission routes and subsequent expansion. We also used the same approach to analyze 261,350 full-length SARS-CoV-2 genomes from the world over 12 months since the outbreak (i.e. all the available viral genomes in the GISAID database as of 25 December 2020). Our study indicates the viral genotypes can be utilized as molecular barcodes in combination with epidemiologic data to monitor the spreading routes of the pandemic and evaluate the effectiveness of control measures.

Nurses' psychological changes and coping strategies during home isolation for the 2019 novel coronavirus in China: A qualitative study.

AIMS: To explore the psychological changes of nurses during home isolation, the factors that related with these changes, and coping strategies in home isolation during the epidemic of COVID-19 in China. DESIGN: A qualitative study based on grounded theory. METHODS: Individual semi-structured telephone interviews were conducted from January 2020-February 2020 with 10 nurses who were isolated at home sharing the experiences of the epidemic of COVID-19. All interviews were audio recorded, transcribed, and analysed using constant comparative data analysis. RESULTS: Analyses of the collected data reveal that the psychological changes of nurses during home isolation reflect a complex, dynamic, and gradually adaptive process that was affected by many factors. Nurses had many negative emotional reactions in the early stages of isolation and positive emotions gradually increased during home isolation. After release from home isolation, they become more confident and calm after. Six categories of coping strategies were identified, including reasoned cognition; autosuggestion; develop healthy protective behaviours; shifting attention; social support; and the power of a role model. CONCLUSIONS: The study provides a better understanding of the psychological changes and the coping strategies used among nurses isolated at home. It is necessary to pay more attention to negative emotions in the early stages of home isolation to help nurses adjust quickly. The coping strategies used by nurses are likely to help those in home isolation reduce negative psychological changes and experience more optimal self-adjustment. IMPACT: This study explored the psychological changes and coping strategies of home isolation among nurses, providing useful advice for psychologists to develop psychological crisis interventions to help individuals reduce negative psychological and have more actively coping strategies when faced sudden stressful infectious diseases.