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1. Particle size determines the accumulation of platinum nanoparticles in the estuarine amphipod, Leptocheirus plumulosus

   https://doi.org/10.1039/d1en00713k  

   Sikder, Mithun ; Eudy, Emily ; Cai, Bo ; Chandler, G. Thomas ; Baalousha, Mohammed ( February 2022 , Environmental Science: Nano)

   Nanoparticles (NPs) typically display a wide distribution of different sizes in aquatic environments, yet little information is available on the impact of particle size dispersity on organismal uptake and elimination. This study investigated uptake and elimination of polyvinylpyrrolidone-coated platinum nanoparticles (PVP-PtNPs) of different sizes ( e.g. , 20.0 ± 4.8 nm, 40.5 ± 4.1 nm, and 70.8 ± 4.2 nm) by the estuarine amphipod Leptocheirus plumulosus . Accumulation and elimination were determined by measuring total Pt body burden in amphipods exposed to PtNPs using inductively coupled plasma-mass spectroscopy, as well as the mass and number PtNP body burden using single particle-ICP-MS (sp-ICP-MS). L. plumulosus accumulated Pt from PtNP suspensions of different sizes from water exposure, mostly ( e.g. , >90%) as PtNPs rather than as dissolved Pt. Mass- and number-based uptake increased with decreases in PtNP size whereas mass- and number-based elimination increased with increasing PtNP size. The residual whole-animal body burden of PtNPs after 48 h elimination increased with decreases in PtNP size, with residual body burdens approximately two-fold higher for amphipods exposed to 20 nm PtNPs than amphipods exposed to 70 nm PtNPs. PtNP influx rate ( k uw ) increased with decreasing NP size, with k uwmore »s of 1.07 ± 0.31, 0.82 ± 0.22, and 0.67 ± 0.10 μg g −1 d −1 for 20 nm, 40 nm, and 70 nm PtNPs, respectively. PtNP efflux rate ( k e ) increased with increasing PtNP size, with k e s of 0.31 ± 0.08, 0.66 ± 0.04, and 0.83 ± 0.07 d −1 for 20 nm, 40 nm, and 70 nm PtNP, respectively. When exposed to mixtures of 40 and 70 nm PtNPs with equal masses, surface areas, or number concentrations of 40 nm and 70 nm PtNPs, L. plumulosus accumulated higher numbers of the 40 nm PtNPs than 70 nm PtNPs from all mixtures. The increased exposure concentration of 70 nm PtNPs in the mixture did not affect the uptake of 40 nm PtNPs, suggesting that in a polydispersed NP suspension the uptake of a given size fraction is independent of other size fractions in the mixture.« less
2. Comparison of excitation wavelengths for in vivo deep imaging of mouse brain

   https://doi.org/10.1117/12.2289065  

   Wang, Mengran ; Wu, Chunyan ; Li, Bo ; Xia, Fei ; Sinefeld, David ; Xu, Chris ; Periasamy, Ammasi ; So, Peter T. ; Xie, Xiaoliang S. ; König, Karsten ( January 2018 , Proc. SPIE 10498, Multiphoton Microscopy in the Biomedical Sciences XVIII,)

   The attenuation of excitation power reaching the focus is the main issue that limits the depth penetration of highresolution imaging of biological tissue. The attenuation is caused by a combination of tissue scattering and absorption. Theoretical model of the effective attenuation length for in vivo mouse brain imaging has been built based on the data of the absorption of water and blood and the Mie scattering of a tissue-like phantom. Such a theoretical model has been corroborated at a number of excitation wavelengths, such as 800 nm, 1300 nm1, and 1700 nm2; however, the attenuation caused by absorption is negligible when compared to tissue scattering at all these wavelength windows. Here we performed in vivo three-photon imaging of Texas Red-stained vasculature in the same mouse brain with different excitation wavelengths, 1700 nm, 1550 nm, 1500 nm and 1450 nm. In particular, our studies include the wavelength regime where strong water absorption is present (i.e., 1450 nm), and the attenuation by water absorption is predicted to be the dominant contribution in the excitation attenuation. Based on the experimental results, we found that the effective attenuation length at 1450 nm is significantly shorter than those at 1700 nm and 1300 nm. Ourmore »results confirm that the theoretical model based on tissue scattering and water absorption is accurate in predicting the effective attenuation lengths for in vivo imaging. The optimum excitation wavelength windows for in vivo mouse brain imaging are at 1300 nm and 1700 nm.« less
3. Design and Simulation of the Bifacial III-V-Nanowire-on-Si Solar Cell

   https://doi.org/10.1557/adv.2019.127  

   Fedorenko, Anastasiia ; Baboli, Mohadeseh A. ; Mohseni, Parsian K. ; Hubbard, Seth M. ( February 2019 , MRS Advances)

   ABSTRACT Rigorous coupled wave analysis (RCWA) simulation was used to model the absorption in periodic arrays of GaAs(0.73)P(0.27) nanowires (NWs) on Si substrates dependent upon the diameter (D), length (L), and spacing (center-to-center distance, or pitch, P) of the NWs. Based on this study, two resonant arrangements for a top NW array sub-cell having the highest limiting short-circuit current densities (J_sc) were found to be close to D = 150 nm, P = 250 nm and D = 300 nm, P = 500 nm, both featuring the same packing density of 0.28. Even though a configuration with thinner NWs exhibited the highest J_sc = 19.46 mA/cm^2, the array with D = 350 nm and P = 500 nm provided current matching with the underlying Si sub-cell with J_sc = 18.59 mA/cm^2. Addition of a rear-side In(0.81)Ga(0.19)As nanowire array with D = 800 nm and P = 1000 nm was found to be suitable for current matching with the front NW sub-cell and middle Si. However, with thinner and sparser In(0.81)Ga(0.19)As NWs with D = 700 nm and P = 1000 nm, the J_scof the bottom sub-cell was increased from 17.35 mA/cm^2 to 18.76 mA/cm^2 using a planar metallic back surfacemore »reflector, thus achieving a current matching with the top and middle cells.« less
4. Size-Dependent Interactions of Lipid-Coated Gold Nanoparticles: Developing a Better Mechanistic Understanding Through Model Cell Membranes and in vivo Toxicity

   https://doi.org/10.2147/IJN.S249622  

   Engstrom AM, Faase RA ( June 2020 , International journal of nanomedicine)

   Introduction: Humans are intentionally exposed to gold nanoparticles (AuNPs) where they are used in variety of biomedical applications as imaging and drug delivery agents as well as diagnostic and therapeutic agents currently in clinic and in a variety of upcoming clinical trials. Consequently, it is critical that we gain a better understanding of how physiochemical properties such as size, shape, and surface chemistry drive cellular uptake and AuNP toxicity in vivo. Understanding and being able to manipulate these physiochemical properties will allow for the production of safer and more efficacious use of AuNPs in biomedical applications. Methods and Materials: Here, AuNPs of three sizes, 5 nm, 10 nm, and 20 nm, were coated with a lipid bilayer composed of sodium oleate, hydrogenated phosphatidylcholine, and hexanethiol. To understand how the physical features of AuNPs influence uptake through cellular membranes, sum frequency generation (SFG) was utilized to assess the interactions of the AuNPs with a biomimetic lipid monolayer composed of a deuterated phospholipid 1.2-dipalmitoyl-d62-sn-glycero-3-phosphocholine (dDPPC). Results and Discussion: SFG measurements showed that 5 nm and 10 nm AuNPs are able to phase into the lipid monolayer with very little energetic cost, whereas, the 20 nm AuNPs warped the membrane conforming it tomore »the curvature of hybrid lipid-coated AuNPs. Toxicity of the AuNPs were assessed in vivo to determine how AuNP curvature and uptake influence cell health. In contrast, in vivo toxicity tested in embryonic zebrafish showed rapid toxicity of the 5 nm AuNPs, with significant 24 hpf mortality occurring at concentrations ≥ 20 mg/L, whereas the 10 nm and 20 nm AuNPs showed no significant mortality throughout the five-day experiment. Conclusion: By combining information from membrane models using SFG spectroscopy with in vivo toxicity studies, a better mechanistic understanding of how nanoparticles (NPs) interact with membranes is developed to understand how the physiochemical features of AuNPs drive nanoparticle–membrane interactions, cellular uptake, and toxicity.« less
5. Systematic evaluating and modeling of SARS-CoV-2 UVC disinfection

   https://doi.org/10.1038/s41598-022-09930-2  

   Freeman, Sebastian ; Kibler, Karen ; Lipsky, Zachary ; Jin, Sha ; German, Guy K. ; Ye, Kaiming ( December 2022 , Scientific Reports)

   Abstract The ongoing COVID-19 global pandemic has necessitated evaluating various disinfection technologies for reducing viral transmission in public settings. Ultraviolet (UV) radiation can inactivate pathogens and viruses but more insight is needed into the performance of different UV wavelengths and their applications. We observed greater than a 3-log reduction of SARS-CoV-2 infectivity with a dose of 12.5 mJ/cm 2 of 254 nm UV light when the viruses were suspended in PBS, while a dose of 25 mJ/cm 2 was necessary to achieve a similar reduction when they were in an EMEM culture medium containing 2%(v/v) FBS, highlighting the critical effect of media in which the virus is suspended, given that SARS-CoV-2 is always aerosolized when airborne or deposited on a surface. It was found that SARS-CoV-2 susceptibility (a measure of the effectiveness of the UV light) in a buffer such as PBS was 4.4-fold greater than that in a cell culture medium. Furthermore, we discovered the attenuation of UVC disinfection by amino acids, vitamins, and niacinamide, highlighting the importance of determining UVC dosages under a condition close to aerosols that wrap the viruses. We developed a disinfection model to determine the effect of the environment on UVC effectiveness with three different wavelengths, 222 nm,more »254 nm, and 265 nm. An inverse correlation between the liquid absorbance and the viral susceptibility was observed. We found that 222 nm light was most effective at reducing viral infectivity in low absorbing liquids such as PBS, whereas 265 nm light was most effective in high absorbing liquids such as cell culture medium. Viral susceptibility was further decreased in N95 masks with 222 nm light being the most effective. The safety of 222 nm was also studied. We detected changes to the mechanical properties of the stratum corneum of human skins when the 222 nm accumulative exposure exceeded 50 J/cm 2 .The findings highlight the need to evaluate each UV for a given application, as well as limiting the dose to the lowest dose necessary to avoid unnecessary exposure to the public.« less