A high-throughput fully automatic biosensing platform for efficient COVID-19 detection.

We propose a label-free biosensor based on a porous silicon resonant microcavity and localized surface plasmon resonance. The biosensor detects SARS-CoV-2 antigen based on engineered trimeric angiotensin converting enzyme-2 binding protein, which is conserved across different variants. Robotic arms run the detection process including sample loading, incubation, sensor surface rinsing, and optical measurements using a portable spectrometer. Both the biosensor and the optical measurement system are readily scalable to accommodate testing a wide range of sample numbers. The limit of detection is 100 TCID50/ml. The detection time is 5 min, and the throughput of one single robotic site is up to 384 specimens in 30 min. The measurement interface requires little training, has standard operation, and therefore is suitable for widespread use in rapid and onsite COVID-19 screening or surveillance.

Highly efficient antifogging/antimicrobial dual-functional chitosan based coating for optical devices.

The coating is frequently adopted to modify the product surface without influencing the essential features of the pristine products. Recently, significant demand has existed for efficient anti-fogging/anti-microbial surfaces in various applications to inhibit microbial growth with high transparency in high-humidity environments, especially in pandemics such as COVID-19. The current study used dual-functional chitosan (Ch) polysaccharide coating with highly hydrophilic properties to be progressively incorporated onto the glass substrates using a simple one-pot technique. Utilizing hot/cold fogging tests and plate count method, the dual-functional Ch/SiO2(3) layer possesses excellent antifogging performance and anti-microbial activity. The hydrogen bonds and electrostatic attractions formed between MSN and Ch result in a higher bound water ratio, as confirmed by the low field nuclear magnetic resonance (LF-NMR). Therefore, based on the chitosan/silica layer, 95 % is the minimum proportion of bound water necessary in the final layer structure to completely inhibit microbial and fogging activities.

Label-free detection of virus-like particles employing rotationally symmetric nanowire array based whispering gallery and quasi-whispering gallery resonant modes onto a silicon platform.

In spite of tremendous advancements in modern diagnostics, there is a dire need for reliable, label-free detection of highly contagious pathogens like viruses. In view of the limitations of existing diagnostic techniques, the present theoretical study proposes a novel scheme of detecting virus-like particles employing whispering gallery and quasi-whispering gallery resonant modes of a composite optical system. Whereas whispering gallery mode (WGM) resonators are conventionally realized using micro-disk, -ring, -toroid or spherical structures, the present study utilizes a rotationally symmetric array of silicon nanowires which offers higher sensitivity compared to the conventional WGM resonator while detecting virus-like particles. Notwithstanding the relatively low quality factor of the system, the underlying multiple-scattering mediated photon entrapment, coupled with peripheral total-internal reflection, results in high fidelity of the system against low signal-to-noise ratio. Finite difference time domain based numerical analysis has been performed to correlate resonant modes of the array with spatial location of the virus. The correlation has been subsequently utilized for statistical analysis of simulated test cases. Assuming detection to be limited by resolution of the measurement system, results of the analysis suggest that for only about 5% of the simulate test cases the resonant wavelength shift lies within the minimum detection range of 0.001-0.01 nm. For a single virus of 160 nm diameter, more than 8 nm shift of the resonant mode and nearly 100% change of quality factor are attained with the proposed nanowire array based photonic structure.

Suitability of DIALux for designing UVC disinfection cabins.

During the present Sars-CoV-2 pandemic, there has been an increase in the development of UVC disinfection systems. Researchers and members of the lighting community shifted their interests to this new field to help develop systems for disinfecting facemasks and other small equipment. In this paper we show that it is possible to use DIALux to simulate the irradiance distribution provided by a lamp emitting in the UVC range. We will compare the results provided by DIALux with those obtained from Zemax OpticStudio in three different scenarios. We compared the minimum, maximum, and mean irradiance at the detection plane. The differences between the two software were less than 12%, 2%, and 6%, respectively. We also compared the contour maps of isoirradiance lines. We conclude that DIALux is well suited for UVC lighting design in the UVC range. We think that this finding will contribute to increasing the design and manufacturing of new UVC disinfection systems needed to fight against the Sars-CoV-2 pandemic.

Characterization of Experimental and Clinical Bioaerosol Generation During Potential Aerosol-Generating Procedures.

BACKGROUND: During medical procedures with the potential to produce aerosols such as bronchoscopy, intubation, or CPR, health-care workers (HCWs) may be exposed to infectious bioaerosols. This scenario is of particular concern when high consequence pathogens such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are circulating. Thousands of HCWs have been infected with SARS-CoV-2. However, the determinants of aerosol generation during medical procedures and their relative risk to HCWs remain poorly characterized. RESEARCH QUESTION: The goal of this study was to characterize aerosols produced during airway intubation by using an uninfected translational animal model and in human subjects undergoing elective aerosol-generating procedures. The study also determined the particle size distribution of generated particles. STUDY DESIGN AND METHODS: Aerosol generation was measured during highly controlled experimental (pig) intubations (N = 16) and elective bronchoscopies in uninfected patients (N = 49) using an optical particle counter. Recovery of normal respiratory flora was used as a surrogate for pathogen dispersion. RESULTS: There was a small but significant (P = .03) decrease in 0.3 µm size particles during highly controlled pig intubations compared with baseline. The concentration of 1.0 µm and 5.0 µm aerosol particles did not significantly change, although oral bacteria were collected from the air. For elective patient bronchoscopies, there was a significant decrease in the generation of larger particles (1.0 µm and 5.0 µm) compared with baseline (P < .01); however, 18 of 39 (46%) patients showed increased aerosol production in 0.3 µm size particles, four of whom exhibited measurable increases. INTERPRETATION: Although the total amount of aerosols produced during intubation and bronchoscopy did not increase significantly relative to preprocedural levels, a small number of participants exhibited a measurable increase in submicron particle emission, meriting further research to delineate determinants of fine particle production during aerosol-generating procedures.