Redox‐responsive nanocarriers using disulfides or thiols have received considerable attention owing to the higher levels of glutathione (GSH) in cancer cells than those in extracellular fluids. ...Nevertheless, the normal‐to‐cancer‐cell selectivity of these nanocarriers has not yet been clarified. Nanocarriers exhibit different cytotoxicities depending on the morphologies they adopt under the redox‐active conditions typically existing in cancerous cells. Therefore, not only GSH levels but also reactive oxygen species (ROS) levels and other complex cancerous cell conditions must be considered for the development of smart drug delivery systems. In this article, we review the structural design of redox‐responsive polymers that exhibit different morphological changes in environments akin to cancerous cells (e. g., GSH‐ and ROS‐abundant conditions). In addition, we propose a molecular design for the spatiotemporal control of nanocarrier morphology depending on the levels of both GSH and ROS upon photoirradiation to increase the cytotoxicity difference between normal and cancer cells.
Redox‐responsive polymeric nanocarriers can transform their morphologies in redox‐active cancerous environments. Here, the differences in the morphologies of polymeric nanocarriers according to their hydrophilic/hydrophobic ratio, locations of redox‐responsive functional groups, and redox states (level of oxidants/reductants) under different exposure conditions are reviewed. Moreover, encapsulated photosensitizers can generate excess oxidants, inducing spatiotemporally controlled nanocarrier morphology changes.
Fines migration driven by fluid flows often causes pore clogging in porous media and thus reduces the permeability of the porous media. The clogging can pose serious problems in various practices, ...such as formation damage in hydrocarbon reservoirs, degradation of fluid withdrawal or injection efficiency, particle‐induced fouling in filtration membranes, or even a risk of sediment failure with geostructures. However, the effect of seepage flow velocity on the spatial growth pattern of fines‐induced pore clogging remains poorly identified. This study explores the pore clogging growth behaviors caused by flow‐driven fines migration and accumulation in porous media and the associated permeability reductions through a series of column experiments and concurrent X‐ray computed tomography imaging. Particularly, the X‐ray image analysis captures the spatial distributions of fines, and thus the homogeneous or heterogeneous (localized) clogging growth pattern under various seepage velocities. Our results reveal that an increase in the seepage flow velocity increases the likelihood of localized clogging growth, attributable to the direct interception of fines by the sand grains. The localized clogging growth causes a faster reduction in permeability than the homogeneous clogging growth. The presented study provides well‐controlled experiment data on fines distribution and associated permeability change, which gives insights into fines‐induced clogging behavior in porous media.
Plain Language Summary
Subsurface fluid flows often accompany migration of fine particles, such as microsized silt and clay minerals. Migrating fine particles can be accumulated at pores, resulting in clogging within geologic formations. Fines‐associated pore clogging unavoidably reduces the permeability of porous media and causes problems in various engineering practices, including declines of fluid productivity from aquifers or hydrocarbon reservoirs and clogging‐induced structural failure in geotechnical aggregate layers, earth dams, and levees. The application also extends to filter fouling in water treatment membranes and channel blockage by engineered nanoparticles in drug or chemical delivery. However, our knowledge on pore clogging growth characteristics during flow‐induced fines migration is primitive. This study unveils two distinct classes of pore clogging growth patterns during flow‐driven fines migration in porous media: localized clogging growth (heterogeneous clogging) and uniformly distributed clogging growth (homogeneous clogging). The results demonstrate that the greater flow velocity increases the likelihood of localized clogging growth which causes much faster reduction in medium permeability than the homogeneous clogging growth. The presented study contributes to better control of fines‐induced clogging growth in porous media, which can be further extended in various engineering practices.
Key Points
This study unveils two distinct classes of fines‐induced clogging growth pattern—localized clogging growth and homogeneous clogging growth
An increase in flow velocity increases likelihood of localized clogging growth, attributable to direct interception of fines by host grains
The localized clogging causes a faster reduction in permeability than the homogeneous clogging
Transparent conducting electrodes (TCEs) are considered to be an essential structural component of flexible organic solar cells (FOSCs). Silver nanowire (AgNW) electrodes are widely used as TCEs ...owing to their excellent electrical and optical properties. The fabrication of AgNW electrodes has faced challenges in terms of forming large uniform interconnected networks so that high conductivity and reproducibility can be achieved. In this study, a simple method for creating an intimate contact between AgNWs that uses cold isostatic pressing (CIP) is demonstrated. This method increases the conductivity of the AgNW electrodes, which enables the fabrication of high‐efficiency inverted FOSCs that have a power conversion efficiency of 8.75% on flexible polyethylene terephthalate with no short circuiting occurring as the CIP process minimizes the surface roughness of the AgNW electrode. This allows to achieve 100% manufacturing yield of FOSCs. Furthermore, these highly efficient FOSCs are proven to only be 2.4% less efficient even for an extreme bending radius of R ≈ 1.5 mm, compared with initial efficiency.
Creating an intimate contact between silver nanowires (AgNWs) that uses cold isostatic pressing (CIP) is demonstrated, which enables to develop highly efficient and reproducible flexible organic solar cells (FOSCs). The fabricated FOSCs using CIP‐treated AgNW electrode show the high‐power conversion efficiency of 8.75%, with only a 2.4% of reduction in efficiency at a bending radius of R ≈ 1.5 mm.
•Biological soil improvement methods using MICP and biopolymers are reviewed.•Engineering properties of MICP- and biopolymer-treated sands are compiled.•Potential applications of MICP and biopolymer ...treatment are discussed.
This study reviews the fundamental mechanisms of biological soil improvement methods—microbially induced calcium carbonate precipitation (MICP) and biopolymer treatment (BPT). Extensive experimental data on various geotechnical properties of sands treated by MICP and BPT are compiled, including the unconfined compressive strength, Mohr-Coulomb shear strength parameters, and permeability. Furthermore, the variations in these engineering parameters are correlated to calcium carbonate content for MICP and biopolymer content for BPT, which provides insights into the extent of biological modification in engineering properties of sands, potential applications, and limitations.
Natural gas hydrates are found widely in oceanic clay-rich sediments, where clay–water interactions have a profound effect on the formation behavior of gas hydrates. However, it remains unclear why ...and how natural gas hydrates are formed in clay-rich sediments in spite of factors that limit gas hydrate formation, such as small pore size and high salinity. Herein, we show that polarized water molecules on clay surfaces clearly promote gas hydrate nucleation kinetics. When water molecules were polarized with an electric field of 104 V/m, gas hydrate nucleation occurred significantly faster with an induction time reduced by 5.8 times. Further, the presence of strongly polarized water layers at the water–gas interface hindered gas uptake and thus hydrate formation, when the electric field was applied prior to gas dissolution. Our findings expand our understanding of the formation habits of naturally occurring gas hydrates in clay-rich sedimentary deposits and provide insights into gas production from natural hydrate deposits.
Mitochondrial oxidation-induced cell death, a physiological process triggered by various cancer therapeutics to induce oxidative stress on tumours, has been challenging to investigate owing to the ...difficulties in generating mitochondria-specific oxidative stress and monitoring mitochondrial responses simultaneously. Accordingly, to the best of our knowledge, the relationship between mitochondrial protein oxidation via oxidative stress and the subsequent cell death-related biological phenomena has not been defined. Here, we developed a multifunctional iridium(III) photosensitiser, Ir-OA, capable of inducing substantial mitochondrial oxidative stress and monitoring the corresponding change in viscosity, polarity, and morphology. Photoactivation of Ir-OA triggers chemical modifications in mitochondrial protein-crosslinking and oxidation (i.e., oxidative phosphorylation complexes and channel and translocase proteins), leading to microenvironment changes, such as increased microviscosity and depolarisation. These changes are strongly related to cell death by inducing mitochondrial swelling with excessive fission and fusion. We suggest a potential mechanism from mitochondrial oxidative stress to cell death based on proteomic analyses and phenomenological observations.
Protein inactivation by reactive oxygen species (ROS) such as singlet oxygen (1O2) and superoxide radical (O2 •–) is considered to trigger cell death pathways associated with protein dysfunction; ...however, the detailed mechanisms and direct involvement in photodynamic therapy (PDT) have not been revealed. Herein, we report Ir(III) complexes designed for ROS generation through a rational strategy to investigate protein modifications by ROS. The Ir(III) complexes are effective as PDT agents at low concentrations with low-energy irradiation (≤ 1 J cm–2) because of the relatively high 1O2 quantum yield (> 0.78), even with two-photon activation. Furthermore, two types of protein modifications (protein oxidation and photo-cross-linking) involved in PDT were characterized by mass spectrometry. These modifications were generated primarily in the endoplasmic reticulum and mitochondria, producing a significant effect for cancer cell death. Consequently, we present a plausible biologically applicable PDT modality that utilizes rationally designed photoactivatable Ir(III) complexes.
Active layer morphology is one of the crucial factors for achieving excellent device performance in polymer solar cells. Recently, solid additives have drawn great attention due to their great ...potential in morphology control, but a detailed explanation about the working mechanism of solid additive systems is still lacking. In this work, we provided an iridium complex-based solid additive (Ir-OH) to control the morphology and crystallinity of the photoactive layer by utilizing the synergetic effect of dual additives 1-chloronaphthalene and Ir-OH. The morphology of the devices with dual additives exhibited appropriate phase separation and domain size, which provided more continuous pathways for charge transport and also exhibited condensed π–π stacking and fine molecular ordering of photoactive materials, resulting in enhanced charge collection probability. Consequently, the treatment of dual additives exhibited enhanced power conversion efficiency (PCE) with enhanced exciton dissociation, charge collection, and reduced bimolecular recombination. In addition, we found that the device with dual additives exhibited strong thermal stability under a constant heat treatment at 130 °C, and the device performance retained 65% during 24 h, showing an improved PCE of 13.89%. We expected that the favorable morphology of active materials in metal complexes can suppress thermal degradation and lead to improved device performance.
Natural and artificial gas hydrates with internal pores of nano to centimeters and weak grain‐cementation have been widely reported, while the detailed formation process of grain‐cementing hydrates ...remains poorly identified. Pore‐scale morphology of carbon dioxide (CO2) hydrate formed in a partially brine‐saturated porous medium was investigated via X‐ray computed microtomography (X‐ray CMT). Emphasis is placed on the pore‐scale growth patterns of gas hydrate, including the growth of dendritic hydrate crystals on preformed hydrate and water‐wetted grains, porous nature of the hydrate phase, volume expansion of more than 200% during the water‐to‐hydrate phase transformation, preference of unfrozen water wetting hydrophilic minerals, and the relevance to a weak cementation effect on macroscale physical properties. The presented pore‐scale morphology and growth patterns of gas hydrate are expected in natural sediment settings where free gas is available for hydrate formation, such as active gas vents, gas seeps, mud volcanoes, permafrost gas hydrate provinces, and CO2 injected formation for the sake of geologic carbon storage; and in laboratory hydrate samples synthesized from partially brine‐saturated sediments or formed from water‐gas interfaces.
Key Points:
Porous gas hydrates are formed from a partially brine‐saturated porous medium
Dendritic hydrates grow at the grain surface and at inter‐particle contacts
Hydrate formation causes a pronounced volume expansion of liquid
Metal–organic framework (MOF) nanoparticles with high porosity and greater tunability have emerged as new drug delivery vehicles. However, premature drug release still remains a challenge in the MOF ...delivery system. Here, we report an enzyme-responsive, polymer-coated MOF gatekeeper system using hyaluronic acid (HA) and PCN-224 nanoMOF. The external surface of nanoMOF can be stably covered by HA through multivalent coordination bonding between the Zr cluster and carboxylic acid of HA, which acts as a gatekeeper. HA allows selective accumulation of drug carriers in CD44 overexpressed cancer cells and enzyme-responsive drug release in the cancer cell environment. In particular, inherent characteristics of PCN-224, which is used as a drug carrier, facilitates the transfer of the drug to cancer cells more stably and allows photodynamic therapy. This HA-PCN system enables a dual chemo and photodynamic therapy to enhance the cancer therapy effect.
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