Staining-Enhanced Peroxidase-Mimicking Gold Nanoparticles in Nano-ELISA for Highly Sensitive Detection of Klebsiella pneumoniae.

Klebsiella pneumoniae, a member of the family Enterobacteriaceae, is a rod-shaped, Gram-negative bacterium, mainly found in the hospital environment and medical tools. It is the leading cause of nosocomial infection, characterized by bloodstream infection, wound site infection, urinary tract infection, and sepsis, mostly in older adults, newborn infants, and immunocompromised patients. This present study demonstrated a novel diagnostic method for K. pneumoniae detection based on the gold nanozyme activity for the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H2O2. The nanozyme activity of AuNPs with staining enhancement was statistically three times higher than that of the bare AuNPs in solid absorption at 650 nm. Nano-ELISA with staining enhancement could detect as low as 102 CFUs/mL of K. pneumoniae concentration, as the cutoff value was determined to be 0.158, which boosted the sensitivity of the immunoreactions by up to 100-fold. The detection limit of our assays was 26.023 CFUs/mL, and the limit of quantification was 78.857 CFUs/mL. There was no cross-reaction against other bacteria, which proved the immunoassays' remarkable specificity for recognizing K. pneumoniae. Taken together, we successfully developed and optimized the highly sensitive and decently specific nano-ELISA strategy that might be applicable for detecting various other bacterial pathogens.

A simple SEIR-V model to estimate COVID-19 prevalence and predict SARS-CoV-2 transmission using wastewater-based surveillance data

Wastewater-based surveillance (WBS) has been widely used as a public health tool to monitor SARS-CoV-2 transmission. However, epidemiological inference from WBS data remains understudied and limits its application. In this study, we have established a quantitative framework to estimate COVID-19 prevalence and predict SARS-CoV-2 transmission through integrating WBS data into an SEIR-V model. We conceptually divide the individual-level viral shedding course into exposed, infectious, and recovery phases as an analogy to the compartments in population-level SEIR model. We demonstrated that the temperature effect on viral losses in the sewer can be straightforwardly incorporated in our framework. Using WBS data from the second wave of the pandemic (Oct 02, 2020 - Jan 25, 2021) in the Great Boston area, we showed that the SEIR-V model successfully recapitulates the temporal dynamics of viral load in wastewater and predicts the true number of cases peaked earlier and higher than the number of reported cases by 16 days and 8.6 folds (R = 0.93), respectively. This work showcases a simple, yet effective method to bridge WBS and quantitative epidemiological modeling to estimate the prevalence and transmission of SARS-CoV-2 in the sewershed, which could facilitate the application of wastewater surveillance of infectious diseases for epidemiological inference and inform public health actions.

A highly sensitive impedimetric sensor based on a MIP biomimetic for the detection of enrofloxacin.

The benefits of molecularly imprinted polymer (MIP) technology in creating artificial receptors to replace natural counterparts have piqued the interest of numerous researchers in recent years. We propose a biomimetic enrofloxacin-MIP for enrofloxacin (ENRO) antigen detection using gold nanoparticles (AuNPs) and MIP methodologies in this study. A self-assembled monomer layer of aminothiophenol was used to immobilize a pre-formed complex of the anti-enrofloxacin monoclonal antibody and enrofloxacin antigen onto the surface of an AuNP coated screen-printed carbon ink electrode (SPCE). The poly-(aminothiophenol) layer thickness was adjusted to entrap and restrict enrofloxacin antigens near the surface. The imprinting and removal of the enrofloxacin antigen in the MIP film were strongly validated by the Raman spectra. The final mAb-MIP sensor had better sensitivity (302 Ω mL ng-1) and a better detection limit (0.05 ng mL-1) than self-assembled monolayer (SAM)-based immunosensors, which had 102 Ω mL ng-1 and 0.1 ng mL-1, respectively.

To mask or not to mask: Modeling the potential for face mask use by the general public to curtail the COVID-19 pandemic

Face mask use by the general public for limiting the spread of the COVID-19 pandemic is controversial, though increasingly recommended, and the potential of this intervention is not well understood. We develop a compartmental model for assessing the community-wide impact of mask use by the general, asymptomatic public, a portion of which may be asymptomatically infectious. Model simulations, using data relevant to COVID-19 dynamics in the US states of New York and Washington, suggest that broad adoption of even relatively ineffective face masks may meaningfully reduce community transmission of COVID-19 and decrease peak hospitalizations and deaths. Moreover, mask use decreases the effective transmission rate in nearly linear proportion to the product of mask effectiveness (as a fraction of potentially infectious contacts blocked) and coverage rate (as a fraction of the general population), while the impact on epidemiologic outcomes (death, hospitalizations) is highly nonlinear, indicating masks could synergize with other non-pharmaceutical measures. Notably, masks are found to be useful with respect to both preventing illness in healthy persons and preventing asymptomatic transmission. Hypothetical mask adoption scenarios, for Washington and New York state, suggest that immediate near universal (80%) adoption of moderately (50%) effective masks could prevent on the order of 17-45% of projected deaths over two months in New York, while decreasing the peak daily death rate by 34-58%, absent other changes in epidemic dynamics. Even very weak masks (20% effective) can still be useful if the underlying transmission rate is relatively low or decreasing: In Washington, where baseline transmission is much less intense, 80% adoption of such masks could reduce mortality by 24-65% (and peak deaths 15-69%), compared to 2-9% mortality reduction in New York (peak death reduction 9-18%). Our results suggest use of face masks by the general public is potentially of high value in curtailing community transmission and the burden of the pandemic. The community-wide benefits are likely to be greatest when face masks are used in conjunction with other non-pharmaceutical practices (such as social-distancing), and when adoption is nearly universal (nation-wide) and compliance is high.

Novel and Innovative Interface as Potential Active Layer in Chem-FET Sensor Devices for the Specific Sensing of Cs.

An innovative novel interface has been designed and developed to be used as a potential active layer in chemically sensitive field-effect transistor (Chem-FET) sensor devices for the specific sensing of Cs+. In this study, the synthesis of a specific Cs+ probe based on calix[4]arene benzocrown ether, its photophysical properties, and its grafting onto a single lipid monolayer (SLM) recently used as an efficient ultrathin organic dielectric in Chem-FETs are reported simultaneously. On the basis of both optical and NMR titration experiments, the probe has shown high selectivity and specificity for Cs+ compared to interfering cations, even if an admixture is used. Additionally, Attenuated Total Reflectance Fourier Transform Infra Red (ATR-FTIR) spectroscopy was successfully used to characterize and prove the efficient grafting of the probe onto a SLM and the formation of the innovative novel sensing layer.

Nonannual seasonality of influenza-like illness in a tropical urban setting.

BACKGROUND: In temperate and subtropical climates, respiratory diseases exhibit seasonal peaks in winter. In the tropics, with no winter, peak timings are irregular. METHODS: To obtain a detailed picture of influenza-like illness (ILI) patterns in the tropics, we established an mHealth study in community clinics in Ho Chi Minh City (HCMC). During 2009-2015, clinics reported daily case numbers via SMS, with a subset performing molecular diagnostics for influenza virus. This real-time epidemiology network absorbs 6000 ILI reports annually, one or two orders of magnitude more than typical surveillance systems. A real-time online ILI indicator was developed to inform clinicians of the daily ILI activity in HCMC. RESULTS: From August 2009 to December 2015, 63 clinics were enrolled and 36 920 SMS reports were received, covering approximately 1.7M outpatient visits. Approximately 10.6% of outpatients met the ILI case definition. ILI activity in HCMC exhibited strong nonannual dynamics with a dominant periodicity of 206 days. This was confirmed by time series decomposition, stepwise regression, and a forecasting exercise showing that median forecasting errors are 30%-40% lower when using a 206-day cycle. In ILI patients from whom nasopharyngeal swabs were taken, 31.2% were positive for influenza. There was no correlation between the ILI time series and the time series of influenza, influenza A, or influenza B (all P > 0.15). CONCLUSION: This suggests, for the first time, that a nonannual cycle may be an essential driver of respiratory disease dynamics in the tropics. An immunological interference hypothesis is discussed as a potential underlying mechanism.