Correlation coefficient-directed label-free characterization of native proteins by surface-enhanced Raman spectroscopy.

Investigation of proteins in their native state is the core of proteomics towards better understanding of their structures and functions. Surface-enhanced Raman spectroscopy (SERS) has shown its unique advantages in protein characterization with fingerprint information and high sensitivity, which makes it a promising tool for proteomics. It is still challenging to obtain SERS spectra of proteins in the native state and evaluate the native degree. Here, we constructed 3D physiological hotspots for a label-free dynamic SERS characterization of a native protein with iodide-modified 140 nm Au nanoparticles. We further introduced the correlation coefficient to quantitatively evaluate the variation of the native degree, whose quantitative nature allows us to explicitly investigate the Hofmeister effect on the protein structure. We realized the classification of a protein of SARS-CoV-2 variants in 15 min, which has not been achieved before. This study offers an effective tool for tracking the dynamic structure of proteins and biomedical research.

Revealing protein binding affinity on metal surfaces: an electrochemical approach.

Revealing the binding affinity between viruses and surfaces of environmental matrices is crucial to evaluate the bioactivity of an immobilized virus and accompanying indirect virus-related infection pathways. The understanding for SARS-CoV-2 remaining infective for even days on stainless steel but only hours on copper is still unclear. Electrochemical chronoamperometry, ultrasensitive to interfacial capacitance on surface species, was used to investigate the binding affinity of SARS-CoV-2 on metal surfaces. SRBD, the surrogate of SARS-CoV-2, shows the highest adsorption capacity on a gold surface, followed by Cu, but lowest on a stainless steel surface. The strong binding of SRBD on copper is a result of the naturally grown Cu2O under ambient conditions. Measurement of electrochemical capacitance provides a simple strategy to explore and evaluate the potential risk of an indirect virus-related infection pathway through conductive environmental matrices.

Demand for longer quarantine period among common and uncommon COVID-19 infections: a scoping review.

BACKGROUND: As one of the non-pharmacological interventions to control the transmission of COVID-19, determining the quarantine duration is mainly based on the accurate estimates of the incubation period. However, patients with coarse information of the exposure date, as well as infections other than the symptomatic, were not taken into account in previously published studies. Thus, by using the statistical method dealing with the interval-censored data, we assessed the quarantine duration for both common and uncommon infections. The latter type includes the presymptomatic, the asymptomatic and the recurrent test positive patients. METHODS: As of 10 December 2020, information on cases have been collected from the English and Chinese databases, including Pubmed, Google scholar, CNKI (China National Knowledge Infrastructure) and Wanfang. Official websites and medias were also searched as data sources. All data were transformed into doubly interval-censored and the accelerated failure time model was applied. By estimating the incubation period and the time-to-event distribution of worldwide COVID-19 patients, we obtain the large percentiles for determining and suggesting the quarantine policies. For symptomatic and presymptomatic COVID-19 patients, the incubation time is the duration from exposure to symptom onset. For the asymptomatic, we substitute the date of first positive result of nucleic acid testing for that of symptom onset. Furthermore, the time from hospital discharge or getting negative test result to the positive recurrence has been calculated for recurrent positive patients. RESULTS: A total of 1920 laboratory confirmed COVID-19 cases were included. Among all uncommon infections, 34.1% (n = 55) of them developed symptoms or were identified beyond fourteen days. Based on all collected cases, the 95th and 99th percentiles were estimated to be 16.2 days (95% CI 15.5-17.0) and 22.9 days (21.7‒24.3) respectively. Besides, we got similar estimates based on merely symptomatic and presymptomatic infections as 15.1 days (14.4‒15.7) and 21.1 days (20.0‒22.2). CONCLUSIONS: There are a certain number of infected people who require longer quarantine duration. Our findings well support the current practice of the extended active monitoring. To further prevent possible transmissions induced and facilitated by such infectious outliers after the 14-days quarantine, properly prolonging the quarantine duration could be prudent for high-risk scenarios and in regions with insufficient test resources.

Risk Factors for Mortality in 220 Patients With COVID-19 in Wuhan, China: A Single-Center, Retrospective Study.

BACKGROUND: An outbreak of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 infection occurred in Wuhan, China, in December 2019. To date, the analysis of fatal cases and the risk factors for death have rarely been reported. METHODS: In this study, 220 adult patients with confirmed and suspected COVID-19 were enrolled. Clinical characteristics, laboratory data, treatments, and complications were compared between 168 survivors and 52 nonsurvivors. Univariable analysis and multivariable logistic regression were used to investigate the risk factors for mortality. RESULTS: A total of 220 patients (168 were discharged and 52 died in the hospital) were enrolled in the study. The median age of all patients was 59.5 (47.0-69.0) years, and the median age of patients who died was significantly older than that of patients who survived (70.5 vs 56.0 years, respectively; P < .001). According to multivariate logistic regression, older age (odds ratio: 1.09, 95% CI: 1.03-1.15; P = .001), initial Sequential Organ Failure Assessment (SOFA) score >2 (37.4, 9.4-148.0; P = .011), and respiratory rate >24 per minute (10.89, 1.47-80.67; P = .019) were independent risk factors for mortality. CONCLUSION: Clinical and laboratory parameters predicting poor prognosis including older age, baseline SOFA score >2, and respiratory rate >24 per minute were identified.