Non-invasive aerosol delivery and transport of gold nanoparticles to the brain

Targeted delivery of nanoscale carriers containing packaged payloads to the central nervous system has potential use in many diagnostic and therapeutic applications. Moreover, understanding of the bio-interactions of the engineered nanoparticles used for tissue-specific delivery by non-invasive delivery approaches are also of paramount interest. Here, we have examined this issue systematically in a relatively simple invertebrate model using insects. We synthesized 5 nm, positively charged gold nanoparticles (AuNPs) and targeted their delivery using the electrospray aerosol generator. Our results revealed that after the exposure of synthesized aerosol to the insect antenna, AuNPs reached the brain within an hour. Nanoparticle accumulation in the brain increased linearly with the exposure time. Notably, electrophysiological recordings from neurons in the insect brain several hours after exposure did not show any significant alterations in their spontaneous and odor-evoked spiking properties. Taken together, our findings reveal that aerosolized delivery of nanoparticles can be an effective non-invasive approach for delivering nanoparticles to the brain, and also presents an approach to monitor the short-term nano-biointeractions

Personal exposure monitoring of PM2.5 among US diplomats in Kathmandu during the COVID-19 lockdown, March to June 2020.

The 2019 Novel Coronavirus SARS-CoV 2 (COVID-191) pandemic has severely impacted global health, safety, economic development and diplomacy. The government of Nepal issued a lockdown order in the Kathmandu Valley for 80 days from 24 March to 11 June 2020. This paper reports associated changes in ambient PM2.5 measured at fixed-site monitors and changes in personal exposure to PM2.5 monitored by APT Minima by four American diplomats who completed monitoring before and during lockdown (24 h for each period per person, 192 person-hours in total). Time activities and use of home air pollution mitigation measures (use of room air cleaners (RACs), sealing of homes) were recorded by standardized diary. We compared PM2.5 exposure level by microenvironment (home (cooking), home (other activities), at work, commuting, other outdoor environment) in terms of averaged PM2.5 concentration and the contribution to cumulative personal exposure (the product of PM2.5 concentration and time spent in each microenvironment). Ambient PM2.5 measured at fixed-sites in the US Embassy and in Phora Durbar were 38.2% and 46.7% lower than during the corresponding period in 2017-2019. The mean concentration of PM2.5 to which US diplomats were exposed was very much lower than the concentrations of ambient levels measured at fixed site monitors in the city both before and during lockdown. Within-person comparisons suggest personal PM2.5 exposure was 50.0% to 76.7% lower during lockdown than before it. Time spent outdoors and cooking at home were large contributors to cumulative personal exposure. Low indoor levels of PM2.5 were achieved at work and home through use of RACs and measures to seal homes against the ingress of polluted air from outside. Our observations indicate the potential reduction in exposure to PM2.5 with large-scale changes to mainly fossil-fuel related emissions sources and through control of indoor environments and activity patterns

Composite Tin Dioxide-Titanium Dioxide Nanostructured Thin Film Electrodes As Lithium-Ion Anodes

An aerosol-chemical vapor deposition technique (ACVD) was utilized in order to deposit highly oriented, one-dimensional nanostructured metal-oxide thin films. Film morphology was controlled using various system parameters in order to obtained the desired columnar morphology. Tin dioxide (SnO 2 ) was chosen as an electrode material due to its high theoretical charge capacity (790 mA-h-g -1 ), and titanium dioxide (TiO 2 ) was chosen for its remarkable stability and low volume change during charging. The columnar morphology is particularly well suited to SnO 2 as the space between the columns allows for accommodation of the large volume expansion the material experiences during charging. Electrodes of SnO 2 columnar nanostructures were first synthesized using ACVD by depositing the structures directly on to the current collector. Depositing directly onto the current collector eliminates the need for binding agents and conductive additives during battery fabrication. Then a layer of TiO 2 was deposited on the surface of the SnO 2 columns using atomic layer deposition. A variety of column heights, ranging from 500 nm to 2 um, and TiO 2 layer thickness, ranging from no TiO 2 to a 100 nm layer, were synthesized and their electrochemical properties investigated. For all electrochemical characterization experiments, Swagelok-type coin cells were fabricated using lithium foil as a counter electrode and 1M LiPF 6 in 50/50 (v/v) EC/DEC as an electrolyte. Optimal electrochemical performance was observed in electrodes with a height of 800 nm and a 15 nm layer of TiO 2 . A rate capability test was performed to determine how the capacity of the electrodes changed at charging rates ranging from 100-2000 mA-g -1 . A stable capacity of 410 mA-h-g -1 was obtained at a charge rate 1000 mA-g -1 ; rapid capacity fade was observed at higher rates. Galvanostatic charge-discharge was performed for each cell for 100 cycles or until failure at a charge rate of 400 mA-g -1 , corresponding approximately to a charge rate of C/2. For the optimal electrode an initial irreversible capacity of 1164 mA-h-g -1 was observed as well as a stable capacity of 530 mA-h-g-1 after 100 cycles. This demonstrates a low cost synthesis of high performance anodes which provides an alternative to conventional electrode synthesis