Non-Steady-State Fickian Diffusion Models Decrease the Estimated Gel Layer Diffusion Coefficient Uncertainty for Diffusive Gradients in Thin-Films Passive Samplers

Determination of diffusion coefficients through gels with non-negligible finite-volume effects in the compartments of the diffusion cell

Diffusion cells are used to measure diffusion coefficients (DM) in gels. These measurements are of interest to understand and predict the availability of nutritive or toxic chemical species in waters, soils and sediments. When the diffusive flux from the donor to the acceptor compartment is constant (steady-state regime), DM is determined from the slope of the linear plot of the acceptor concentration vs time. However, at long enough times, there is a non-negligible concentration depletion in the donor compartment concomitant to a concentration increase in the acceptor compartment. Accordingly, the accumulation plot bends downwards preventing a linear fitting. This is the case of metals whose solubility (especially depending on pH values) limits the concentration in the donor compartment and the time required to reach concentrations above the limit of quantification in the acceptor compartment implies a non-negligible decrease of the concentration in the donor compartment. In this work, a simple linear regression is shown to provide the diffusion coefficient values from experiments exhibiting finite-volume effects. This expression is validated against rigorous numerical simulation as well as reported values in the literature. Diffusion coefficients of Zn, Ni and Pb in agarose cross-linked polyacrylamide (APA) gels (used in Diffusive Gradients in Thin-Film devices, DGT) are determined under finite-volume effects. The resulting values agree with those obtained under the standard linear regime.

"Yin-Yang philosophy" for the design of anticancer drug delivery nanoparticles

Understanding the in vivo transport process provides guidelines for designing ideal nanoparticles (NPs) with higher efficacy and fewer off-target effects. Many factors, such as particle size, morphology, surface potential, structural stability, and etc., may influence the delivering process of NPs due to the existence of various physiological barriers within the body. Herein, we summarise the distinct influences of NP physicochemical properties on the four consecutive in vivo transport steps: (1) navigating with bloodstream within blood vessels, (2) transport across vasculature walls into tumour tissues, (3) intratumoural transport through the interstitial space, and (4) cellular uptake & intracellular delivery by cancerous cells. We found that the philosophy behind the current consensus for NP design has certain similarities to the "Yin-Yang" theory in traditional Chinese culture. Almost all physicochemical properties, regardless of big or small sizes, long or short length, positive or negative zeta potentials, are double-edged swords. The balance of potential benefits and side effects, drug selectivity and accessibility should be fully considered when optimising particle design, similar to the "Yin-Yang harmony". This paper presents a comprehensive review of the advancements in NPs research, focusing on their distinct features in tumour targeting, drug delivery, and cell uptake. Additionally, it deliberates on future developmental trends and potential obstacles, thereby aiming to uncover the ways these characteristics influence the NPs' biological activity and provide theoretical guidance for the targeted delivery of NPs.

New PFASs Identified in AFFF Impacted Groundwater by Passive Sampling and Nontarget Analysis

Monitoring contamination from per- and polyfluoroalkyl substances (PFASs) in water systems impacted by aqueous film-forming foams (AFFFs) typically addresses a few known PFAS groups. Given the diversity of PFASs present in AFFFs, current analytical approaches do not comprehensively address the range of PFASs present in these systems. A suspect-screening and nontarget analysis (NTA) approach was developed and applied to identify novel PFASs in groundwater samples contaminated from historic AFFF use. A total of 88 PFASs were identified in both passive samplers and grab samples, and these were dominated by sulfonate derivatives and sulfonamide-derived precursors. Several ultrashort-chain (USC) PFASs (≤C3) were detected, 11 reported for the first time in Australian groundwater. Several transformation products were identified, including perfluoroalkane sulfonamides (FASAs) and perfluoroalkane sulfinates (PFASis). Two new PFASs were reported (((perfluorohexyl)sulfonyl)sulfamic acid; m/z 477.9068 and (E)-1,1,2,2,3,3,4,5,6,7,8,8,8-tridecafluorooct-6-ene-1-sulfonic acid; m/z 424.9482). This study highlights that several PFASs are overlooked using standard target analysis, and therefore, the potential risk from all PFASs present is likely to be underestimated.