The Dynamics of SARS-CoV-2 Infectivity with Changes in Aerosol Microenvironment

Understanding the factors that influence the airborne survival of viruses such as SARSCoV2 in aerosols is important for identifying routes of transmission and the value of various mitigation strategies for preventing transmission. We present measurements of the stability of SARSCoV2 in aerosol droplets (5 to 10 micrometres equilibrated radius) over timescales spanning from 5 seconds to 20 minutes using a novel instrument to probe survival in a small population of droplets (typically 5-10) containing ~1 virus/droplet. Measurements of airborne infectivity change are coupled with a detailed physicochemical analysis of the airborne droplets containing the virus. A decrease in infectivity to 10 % of the starting value was observable for SARS-CoV-2 over 20 minutes, with a large proportion of the loss occurring within the first 5 minutes after aerosolisation. The initial rate of infectivity loss was found to correlate with physical transformation of the equilibrating droplet; salts within the droplets crystallise at RHs below 50% leading to a near instant loss of infectivity in 50 to 60% of the virus. However, at 90% RH the droplet remains homogenous and aqueous, and the viral stability is sustained for the first 2 minutes, beyond which it decays to only 10% remaining infectious after 10 minutes. The loss of infectivity at high RH is consistent with an elevation in the pH of the droplets, caused by volatilisation of CO2 from bicarbonate buffer within the droplet. Three different variants of SARS-CoV-2 were compared and found to have a similar degree of airborne stability at both high and low RH.

Aqueous-Mediated Synthesis and Characterization of Gelatin Methacryloyl for Biomedical Applications

In recent years, gelatin methacryloy¬l (GelMA)-based hydrogels have been widely used in many biomedical applications, particularly tissue engineering, due to their biocompatibility and tunable physicochemical, mechanical, and other functional properties. Phosphate buffer saline (PBS) or carbonate-bicarbonate buffer are frequently used to make GelMA. In this article, the authors provide an elegant aqueous-mediated synthesis and characterization of GelMA. The experimental conditions were optimized and extensively discussed. The results of proton nuclear magnetic resonance (1H NMR) and Fourier transform infrared spectroscopy (FTIR) confirmed the formation of GelMA with characteristic absorption peaks and chemical functional groups. The morphological analysis done with scanning electron microscopy (SEM) showed the porous nature of the GelMA with an average pore size of 80 microns. It was also found that the gelation properties of aqueous-mediated GelMA hydrogel were highly tunable by varying the percentage of gel concentration, which yields a wide range of tunable physicochemical properties. The preparation of this kind of aqueous-mediated GelMA is cost-effective compared to their counterparts and easy to prepare in laboratory settings with high yield under optimal conditions.

Spontaneous alteration of blood pH by a bicarbonate buffer system during experimental hypercalcaemia in cows

Introduction Maintaining mineral homeostasis as well as the secretion and metabolism of mineralotropic hormones is important for healthy of periparturient dairy cows. To increase the activity of mineralotropic hormones, blood pH can be adjusted. The purpose of this study was to investigate changes in blood pH and the mechanism of action of this change in induced hypercalcaemic cows. Material and Methods Six non-lactating Holstein cows were used in a 2 × 2 crossover design. To induce hypercalcaemia, calcium borogluconate was administered subcutaneously to experimental cows and normal saline was administered subcutaneously to control cows. Blood and urine samples were collected serially after administration. Whole blood without any anticoagulant was processed with a portable blood gas analyser. Plasma concentration and urinary excretion of calcium were measured. Results In hypercalcaemic cows, both blood and urine calcium levels were significantly increased at 8 h compared to those at 0 h (P < 0.05), and a spontaneous increase in blood pH was also observed. The calcium concentration in plasma was highest at 2 h after administration (3.02 ± 0.27 mmol/L). The change in pH correlated with that in bicarbonate (r = 0.781, P < 0.001) rather than that in partial pressure of CO2 (r = 0.085, P = 0.424). Conclusion Hypercalcaemia induced a spontaneous change in blood pH through the bicarbonate buffer system and this system may be a maintainer of calcium homeostasis.

Development of an ELAA kit to detect neomycin in milk

Antibiotics used in livestock production offer various benefits as an antimicrobial agent, growth promoter, and feed effective improvement. However, the abuse of antibiotics leads to antibiotic resistance which may seriously threaten human and animal welfare, and growing levels of antibiotics or antibiotic-resistant bacteria in the environment increase the numbers of drug-resistant infection outbreaks. Therefore, many detection methods have been being developed to quickly assess antibiotic content and its residues in foods. Among many analytical methods, the aptamer-based biosensor has considerable attention for its outstanding advantages such as high specificity, high sensitivity, and good selectivity. We use the ELAA (Enzyme-Linked Aptamer Assay) method - a variant of ELISA - which has a high affinity with neomycin. Firstly, we investigated different buffers to create the Neo-BSA complex. As result, 2-(N-morpholino) ethanesulfonic acid (MES) buffer pH 7 was found with the best results. Next, to help the Neo-BSA complex be fixed well on polystyrene wells, we surveyed various buffers and found the coating buffer (50mM Bicarbonate buffer, pH 9.6) rated as the most suitable for this process. In addition, the quality of the kit is also assessed through competitive ELAA reaction components. Therefore, we have investigated and optimized conditions such as aptamer concentration 25 nM in PBS buffer, and the biotinized aptamers did not need heat treatment prior to joining the reaction. From the results, we have successfully developed a calibration curve for antibiotic residue in milk using the ELAA technique, linear range 0,1 ng/mL and 100 ng/mL. Then, we initially surveyed 20 milk samples found that the ELAA method was consistent with the results from LC-MS/MS was obtained showing no difference between the two methods. We continued to test the samples to determine the kit’s sensitivity and specificity. The results showed that the kit has a specificity and sensitivity of 100%. Finally, LOD and LOQ value had xavg = 0.448; SD = 0.22, LOD = xavg + 3SD = 1.11 (ng / ml); LOQ = x tb + 10SD = 2.65 (ng / mL). We will continue to optimize the kit before being brought to the market.

High flux membrane based on in-situ formation of zirconia layer coated the polyethersulfone substrate for ions separation

A flawless, extremely loose, and efficient for multivalent ions separation membrane has been successfully synthesized by the in-situ formation approach. The as-synthesized nanofiltration (NF) membrane, NF_PES-Zr, proceeded from a thin film layer of nanoparticles (NPs) zirconium coated the platform of polyethersulfone (PES) ultrafiltration (UF) membrane through a bio-glue made from dopamine hydrochloric and sodium bicarbonate buffer. The estimation of the average pore size of the novel organic-inorganic NF membrane NF_PES-Zr using the filtration velocity approach of GUEROUT-ELFORD-FERRY was close to 0.9 nm. NF_PES-Zr membrane holds a record in permeate water flux release of about 62.5 L.m–2.h–1 and was revealed to be effective for multivalent ions separation. A 5 days-test performed on NF_PES-Zr demonstrated its long-term stability and showed a rejection rate of 93.4% and 37.8% respectively for Ca2+ and Na+.

Inferences of Carbon Dioxide in Present-Day Cell Culture Systems: An Unacknowledged Problem and Perspectives

The impact of cell culture technology has been immense in the field of research and pharmaceutical sciences. Suitable environmental conditions are paramount need in order to maintain the cell line in an in-vitro condition. Since the biological processes are highly susceptible to acid-base chemistry, variations among the factors will have a severe effect on cellular integrity that often leads to hypercapnia and senescence of the cells. pH regulation in the cell culture environment is a fundamental biological phenomenon of great significance for the growth and metabolism of cells. This review focuses on the implications of the two critical factors carbon dioxide (CO2), pH, and their correlated effects in the mammalian culture system. Bicarbonate buffer plays a vital role in maintaining homeostasis as dissolved CO2 hydration occurs in bicarbonate (HCO3-) and H+ equilibriums. If pH is not controlled, inhibition of CO2 causes acidification in the medium. In contrast, if pH is not regulated by integrating essential requirements, the equilibrium reaction shifts to the right towards the hydrogen ions that maintains the balance. Despite a few literatures exhibiting the role of carbon dioxide in cell culture, the present review distinguishes from them by showing the effects of CO2 in the in-vitro environment in maintaining the pH balance and cellular integrity. Thus, ensuring the proper mechanism of the utilization of CO2 and pH in the cell culture system will undoubtedly lead to the exploration of enormous concepts in the present crucial study.

Using nutrient-rich solutions and adding multiple cytoprotective agents as new strategies to develop lung preservation solutions

Commonly, donor lungs are preserved with low potassium dextran glucose solution at low temperature. We hypothesized that adding nutrients and/or cytoprotective agents to preservation solutions improves donor lung quality. Human lung epithelial cells and human pulmonary microvascular endothelial cells cultured at 37ºC with serum containing medium were switched to designated testing solutions at 4ºC with 50% O2 for different cold ischemic time, followed by switching back to serum containing culture medium at 37ºC to simulate reperfusion. We found that bicarbonate buffer system should be avoided in preservation solution. When pH was maintained at physiological levels, cell culture media showed better cell survival than in low potassium dextran glucose solution. Phosphate buffered cell culture media were further improved by adding colloid dextran 40. When rat donor lungs were preserved at 4ºC for 24 h, RPMI-1640(p) medium plus dextran 40 or adding cytoprotective agents (alpha 1 antitrypsin, raffinose and glutathione) to low potassium dextran glucose solution prevented alveolar wall swelling, apoptosis, activation of endothelial cells and cellular edema. Using nutrient-rich solution and/or adding multiple cytoprotective agents is a new direction for designing and developing organ preservation solutions. Cell culture model, as a screening tool reduces the use of animals and provides potential underlying mechanisms.