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International Journal of Biological... Jul 2024Stimuli-responsive optical hydrogels are widely used in various fields including environmental sensing, optical encryption, and intelligent display manufacturing....
Stimuli-responsive optical hydrogels are widely used in various fields including environmental sensing, optical encryption, and intelligent display manufacturing. However, these hydrogels are susceptible to water losses when exposed to air, leading to structural damage, significantly shortened service lives, and compromised durability. This study presents mechanically robust, environmentally stable, and multi-stimuli responsive optical organohydrogel fibers with customizable iridescent colors. These fibers are fabricated by incorporating tunicate cellulose nanocrystals, alginate, and acrylamide in a glycerol-water binary system. The synthesized fibers exhibit high strength (1.38 MPa), moisture retention capabilities, and elastic properties. Furthermore, a sensor based on these fibers demonstrates high- and low-temperature resistance along with stimuli-responsive characteristics, effectively detecting changes in environmental humidity and strains. Moreover, the fiber sensor demonstrates continuous, repeatable, and quantitatively predictable moisture discoloration responses across a humidity range of 11 % and 98 %. During strain sensing, the optical-organohydrogel-based sensor demonstrates a large working strain (50 %) and excellent cycling stability, underscoring its potential for effectively monitoring a wide range of intricate human motions. Overall, the synthesized fibers and their simple fabrication method can elicit new avenues for numerous related applications including the large-scale implementation of advanced wearable technology.
PubMed: 38960229
DOI: 10.1016/j.ijbiomac.2024.133501 -
The Science of the Total Environment Jul 2024Conventional plastics have become a major environmental concern due to their persistence and accumulation in marine ecosystems. The development of potential degradable...
Conventional plastics have become a major environmental concern due to their persistence and accumulation in marine ecosystems. The development of potential degradable polymers (PBP), such as polyhydroxyalkanoates (PHAs) and polylactic acid (PLA), has gained attention as an alternative to mitigate plastic pollution, since they have the potential to biodegrade under certain conditions, and their production is increasing as replacement of conventional polyolefins. This study aimed to assess and compare the toxicity of leachates of pre-compounding PBP (PLA and the PHA, polyhydroxybutyrate-covalerate (PHBv)) and polypropylene (PP) on five marine planktonic species. A battery of standard bioassays using bacteria, microalgae, sea urchin embryos, mussel embryos and copepod nauplii was conducted to assess the toxicity of leachates from those polymers. Additionally, the presence of chemical additives in the leachates was also verified through GC-MS and LC-HRMS analysis. Results showed that PHBv leachates exhibited higher toxicity compared to other polymers, with the microalgae Rhodomonas salina, being the most sensitive species to the tested leachates. On the other hand, PP and PLA generally displayed minimal to no toxicity in the studied species. Estimated species sensitivity distribution curves (SSD) show that PHBv leachates can be 10 times more hazardous to marine plankton than PP or PLA leachates, as demonstrated by the calculated Hazardous Concentration for 5 % of species (HC). Qualitative chemical analysis supports the toxicological results, with 80 % of compounds being identified in PHBv leachates of which 2,4,6-trichlorophenol is worth mentioning due to the deleterious effects to aquatic biota described in literature. These findings underscore the fact that whereas environmental persistence can be targeted using PBP, the issue of chemical safety remains unsolved by some alternatives, such as PHBv. Gaining a comprehensive understanding of the toxicity profiles of PBP materials through a priori toxicological risk assessment is vital for their responsible application as alternatives to conventional plastics.
PubMed: 38960198
DOI: 10.1016/j.scitotenv.2024.174403 -
The Science of the Total Environment Jul 2024Development of effective prevention and mitigation strategies for marine plastic pollution requires a better understanding of the pathways and transport mechanisms of...
Development of effective prevention and mitigation strategies for marine plastic pollution requires a better understanding of the pathways and transport mechanisms of plastic waste. Yet the role of estuaries as a key interface between riverine inputs of plastic pollution and delivery to receiving marine environments remains poorly understood. This study quantified the concentration and distribution of microplastics (MPs) (50-3175 μm) in surface waters of the St. Lawrence Estuary (SLE) in eastern Canada. Microplastics were identified and enumerated based on particle morphology, colour, and size class. Fourier Transform Infrared (FTIR) spectroscopy was used on a subset of particles to identify polymers. Generalized linear models (Gamma distribution with log-link) examined the relationship between MP concentrations and oceanographic variables and anthropogenic sources. Finally, a risk assessment model, using MP concentrations and chemical hazards based on polymer types, estimated the MP pollution risk to ecosystem health. Mean surface MP concentration in the SLE was 120 ± 42 SD particles m; MP concentrations were highest in the fluvial section and lowest in the Northwest Gulf of St. Lawrence. However, MP concentrations exhibited high heterogeneity along the length and width of the SLE. Microplastics were elevated at stations located closer to wastewater treatment plant outflows and downstream sites with more agricultural land. Black, blue, and transparent fibers and fragments ≤250 μm were most commonly encountered. Predominant polymer types included polyethylene terephthalate, regenerated cellulose, polyethylene, and alkyds. While the overall risk to ecosystem health in the entire estuary was considered low, several stations, particularly near urban centres were at high or very high risk. This study provides new insights into the quantification and distribution of MPs and first estimates of the risk of MP pollution to ecosystem health in one of the world's largest estuaries.
PubMed: 38960195
DOI: 10.1016/j.scitotenv.2024.174324 -
Journal of Molecular Biology Jul 2024Septins are filamentous nucleotide-binding proteins which can associate with membranes in a curvature-dependent manner leading to structural remodelling and barrier...
Septins are filamentous nucleotide-binding proteins which can associate with membranes in a curvature-dependent manner leading to structural remodelling and barrier formation. Ciona intestinalis, a model for exploring the development and evolution of the chordate lineage, has only four septin-coding genes within its genome. These represent orthologues of the four classical mammalian subgroups, making it a minimalist non-redundant model for studying the modular assembly of septins into linear oligomers and thereby filamentous polymers. Here, we show that C. intestinalis septins present a similar biochemistry to their human orthologues and also provide the cryo-EM structures of an octamer, a hexamer and a tetrameric sub-complex. The octamer, which has the canonical arrangement (2-6-7-9-9-7-6-2) clearly shows an exposed NC-interface at its termini enabling copolymerization with hexamers into mixed filaments. Indeed, only combinations of septins which had CiSEPT2 occupying the terminal position were able to assemble into filaments via NC-interface association. The CiSEPT7-CiSEPT9 tetramer is the smallest septin particle to be solved by Cryo-EM to date and its good resolution (2.7Å) provides a well-defined view of the central NC-interface. On the other hand, the CiSEPT7-CiSEPT9 G-interface shows signs of fragility permitting toggling between hexamers and octamers, similar to that seen in human septins but not in yeast. The new structures provide insights concerning the molecular mechanism for cross-talk between adjacent interfaces. This indicates that C. intestinalis may represent a valuable tool for future studies, fulfilling the requirements of a complete but simpler system to understand the mechanisms behind the assembly and dynamics of septin filaments.
PubMed: 38960133
DOI: 10.1016/j.jmb.2024.168693 -
Factors influencing microplastic abundances in the sediments of a seagrass-dominated tropical atoll.Environmental Pollution (Barking, Essex... Jul 2024Seagrass meadows are one of the world's most diverse ecosystems offering habitats for an extensive array of species, as well as serving as protectors of coral reefs and...
Seagrass meadows are one of the world's most diverse ecosystems offering habitats for an extensive array of species, as well as serving as protectors of coral reefs and vital carbon sinks. Furthermore, they modify hydrodynamics by diminishing water flow velocities and enhancing sediment deposition, indicating the potential for microplastic accumulation in their sediments. The build-up of microplastics could potentially have ecological impacts threatening to ecosystems, however little is known about microplastic abundance and controlling factors in seagrass sediments. Here we investigated microplastic characteristics and abundances within sediments underlying four seagrass meadow sites on the Turneffe Atoll, Belize. Sediment cores were collected and sub-sampled to include a range of replicate surface sediments (0-4 cm) and depth cores (sediment depths 0-2, 2-5, 5-10, 10-20 and 20-30 cm). These were analysed using 25 μm resolution μFTIR, with spectral maps processed using siMPle software. Microplastics were prevalent across the sites with an abundance range (limit of detection (LOD) blank-corrected) of < LOD to 17137 microplastics kg dw found on the east side of the atoll. However, their abundances varied greatly between the replicate samples. Polyethylene and polypropylene were the most commonly detected polymers overall, although the dominant polymer type varied between sites. There were no differences in the abundance of microplastics between sites, nor could abundance distributions be explained by seagrass cover. However, abundances of microplastics were highest in sediments with lower proportions of fine grained particles (clay, <4 μm) suggesting that hydrodynamics override seagrass effects. Additionally, no patterns were seen between microplastic abundance and depth of sediment. This suggests that microplastic abundance and distribution in seagrass meadows may vary significantly depending on the specific geographical locations within those meadows, and that more complex hydrodynamic factors influence spatial variability at a localised scale.
PubMed: 38960123
DOI: 10.1016/j.envpol.2024.124483 -
Environmental Pollution (Barking, Essex... Jul 2024Sundarban, a Ramsar site of India, has been encountering an ecological threat due to the presence of microplastic (MP) wastes generated from different anthropogenic...
Characterization and ecological risk assessment of microplastics accumulated in sea water, sand, sediment, shell water and selected tissues of hermit crab of Sundarban Biosphere Reserve.
Sundarban, a Ramsar site of India, has been encountering an ecological threat due to the presence of microplastic (MP) wastes generated from different anthropogenic sources. Clibanarius longitarsus, an intertidal hermit crab of Sundarban Biosphere Reserve, resides within the abandoned shell of a gastropod mollusc, Telescopium telescopium. We characterized and estimated the MP in the gills and gut of hermit crab, as well as in the water present in its occupied gastropod shell. The average microplastic abundance in sea water, sand and sediment were 0.175 ± 0.145 MP L, 42 ± 15.03 MP kg and 67.63 ± 24.13 MP kg respectively. The average microplastic load in hermit crab was 1.94 ± 0.59 MP crab, with 33.89 % and 66.11 % in gills and gut respectively. Gastropod shell water exhibited accumulation of 1.69 ± 1.43 MP L. Transparent and fibrous microplastics were documented as the dominant polymers of water, sand and sediment. Shell water exhibited the prevalence of green microplastics followed by transparent ones. Microscopic examination revealed microplastics with 100-300 μm size categories were dominant across all abiotic compartments. ATR-FTIR and Raman spectroscopy confirmed polyethylene and polypropylene as the prevalent polymers among the five identified polymers of biotic and abiotic components. The target group index indicated green and black as the preferable microplastics of crab. The ecological risk analysis indicated a considerable level of environmental pollution risk in Sundarban and its inhabiting organisms. This important information base may facilitate in developing a strategy of mitigation to limit the MP induced ecological risk at Sundarban Biosphere Reserve.
PubMed: 38960120
DOI: 10.1016/j.envpol.2024.124484 -
Acta Biomaterialia Jul 2024Decellularized extracellular matrix (dECM) hydrogels provide tissue-specific microenvironments which accommodate physiological cellular phenotypes in 3D in vitro cell...
Decellularized extracellular matrix (dECM) hydrogels provide tissue-specific microenvironments which accommodate physiological cellular phenotypes in 3D in vitro cell cultures. However, their formation hinges on collagen fibrillogenesis, a complex process which limits regulation of physicochemical properties. Hence, achieving reproducible results with dECM hydrogels poses as a challenge. Here, we demonstrate that thiolation of solubilized liver dECM enables rapid formation of covalently crosslinked hydrogels via Michael type addition, allowing for precise control over mechanical properties and superior organotypic biological activity. Investigation of various decellularization methodologies revealed that treatment of liver tissue with Triton X-100 and ammonium hydroxide resulted in near complete DNA removal with significant retention of the native liver proteome. Chemical functionalization of pepsin-solubilized liver dECMs via 1-ethyl-3(3-dimethylamino)propyl carbodiimide (EDC)/N-hydroxysuccinimide (NHS) coupling of L-Cysteine created thiolated liver dECM (dECM-SH), which rapidly reacted with 4-arm polyethylene glycol (PEG)-maleimide to form optically clear hydrogels under controlled conditions. Importantly, Young's moduli could be precisely tuned between 1 - 7 kPa by varying polymer concentrations, enabling close replication of healthy and fibrotic liver conditions in in vitro cell cultures. Click dECM-SH hydrogels were cytocompatible, supported growth of HepG2 and HepaRG liver cells, and promoted liver-specific functional phenotypes as evidenced by increased metabolic activity, as well CYP1A2 and CYP3A4 activity and excretory function when compared to monolayer culture and collagen-based hydrogels. Our findings demonstrate that click-functionalized dECM hydrogels offer a highly controlled, reproducible alternative to conventional tissue-derived hydrogels for in vitro cell culture applications. STATEMENT OF SIGNIFICANCE: Traditional dECM hydrogels face challenges in reproducibility and mechanical property control due to variable crosslinking processes. We introduce a click hydrogel based on porcine liver decellularized extracellular matrix (dECM) that circumnavigates these challenges. After optimizing liver decellularization for ECM retention, we integrated thiol-functionalized liver dECM with polyethylene-glycol derivatives through Michael-type addition click chemistry, enabling rapid, room-temperature gelation. This offers enhanced control over the hydrogel's mechanical and biochemical properties. The resultant click dECM hydrogels mimic the liver's natural ECM and exhibit greater mechanical tunability and handling ease, facilitating their application in high-throughput and industrial settings. Moreover, these hydrogels significantly improve the function of HepaRG-derived hepatocytes in 3D culture, presenting an advancement for liver tissue cell culture models for drug testing applications.
PubMed: 38960110
DOI: 10.1016/j.actbio.2024.06.037 -
Chemosphere Jul 2024In this report, we have developed highly water soluble and stable silver nanoparticles (Ag NPs) utilizing N-Cholyl Mercapto Histidine (NCMH) as a reducing and...
In this report, we have developed highly water soluble and stable silver nanoparticles (Ag NPs) utilizing N-Cholyl Mercapto Histidine (NCMH) as a reducing and stabilizing agent with near the primary critical micellar concentration (CMC) under ambient sunlight irradiation. Moreover, The NCMH was firstly synthesized by demonstrating the reaction between cholic acid and 2- Mercapto Histidine through a simple acid amine coupling approach. The primary and secondary CMC of NCMH surfactant was measured by pyrene (1× 10 M) as a fluorescent probe, and values were found to be 3.2 and 13.1 mM respectively. The synthesised Ag NPs showed at neutral pH and highly stable for more than one year without any noticeable aggregation. The TEM analysis displays the synthesized Ag NPs having a spherical shape and average size of 9.6 ± 0.5 nm. The synthesis of stabilized Ag NPs was used for ultra-sensitive and selective detection of Hg ions in aqueous medium were monitored by Uv-visible spectrometer and naked eyes with a lowest limit of detection (LOD) 7 nM. The photo-catalytic degradation of methyl orange (MO) by utilizing Ag NPs as nano-catalyst exhibits a potential degradation within a study period of 180 min. Concluding that, facile and cost effective green synthesis of NCMH capped Ag NPs possess excellent reducing ability towards the selective detection of Hg ions along with photo-catalytic degradation of MO dye. These true findings detached an innovative pathway of Ag NPs towards the reactivity against the catalytic activity of dye degradation and selective sensing of Hg ions. Thus it paves the way for extensive range of novel potential applications of Ag NPs in various environment friendly approaches of sensitive and analytical protocol in the future.
PubMed: 38960050
DOI: 10.1016/j.chemosphere.2024.142748 -
Physics in Medicine and Biology Jul 2024To develop and benchmark a novel 3D dose verification technique consisting of polymer-gel-dosimeter (PGD) with cone-beam-CT (CBCT) readout through a two-institution...
To develop and benchmark a novel 3D dose verification technique consisting of polymer-gel-dosimeter (PGD) with cone-beam-CT (CBCT) readout through a two-institution study. The technique has potential for wide and robust applicability through reliance on CBCT readout. Approach: Three treatment plans (3-Field, TG119-C-shape spine, 4-target SRS) were created by two independent institutions (Institution A and B). A Varian Truebeam LINAC was used to deliver the plans to NIPAM polymer gel dosimeters produced at both institutions using an identical approach. For readout, a slow CBCT scan mode was used to acquire pre- and post-irradiation images of the gel (1 mm slice thickness). Independent gel analysis tools were used to process the PGD images (A: VistaAce software, B: in-house MATLAB code). Comparing planned and measured doses, the analysis involved a combination of 1D line profiles, 2D contour plots, and 3D global gamma maps (criteria ranging between 2%1mm and 5%2mm, with a 10% dose threshold). Main Results: For all gamma criteria tested, the 3D gamma pass rates were all above 90% for 3-field and 88% for the SRS plan. For the C-shape spine plan, we benchmarked our 2% 2mm result against previously published work using film analysis (93.4%). For 2%2mm, 99.4% (Institution A data), and 89.7% (Institution B data) were obtained based on VistaAce software analysis, 83.7% (Institution A data), and 82.9% (Institution B data) based on MATLAB. Significance: The benchmark data demonstrate that when two institutions follow the same rigorous procedures gamma passing rates up to 99%, for 2%2mm criteria can be achieved for substantively different treatment plans. The use of different software and calibration techniques may have contributed to the variation in the 3D gamma results. By sharing the data across institutions, we observe the gamma passing rate is more consistent within each pipeline, indicating the need for standardized analysis methods.
PubMed: 38959910
DOI: 10.1088/1361-6560/ad5eef -
Biomedical Physics & Engineering Express Jul 2024Biocompatible polymer-based scaffolds hold great promise for neural repair, especially when they are coupled with electrostimulation to induce neural differentiation. In...
Biocompatible polymer-based scaffolds hold great promise for neural repair, especially when they are coupled with electrostimulation to induce neural differentiation. In this study, a combination of polyacrylonitrile/polyaniline (PAN/PANI) and Carbon Nanotubes (CNTs) were used to fabricate three different biomimetic electrospun scaffolds (samples 1, 2 and 3 containing 0.26 wt%, 1 wt% and 2 wt% of CNTs, respectively). These scaffolds underwent thorough characterization for assessing electroconductivity, tensile strength, wettability, degradability, swelling, XRD, and FTIR data. Notably, scanning electron microscopy (SEM) images revealed a three-dimensional scaffold morphology with aligned fibers ranging from 60 nm to 292 nm in diameter. To comprehensively investigate the impact of electrical stimulation on the nervous differentiation of the stem cells seeded on these scaffolds, cell morphology and adhesion were assessed based on SEM images. Additionally, scaffold biocompatibility was studied through MTT assay. Importantly, Real-Time PCR results indicated the expression of neural markers-Nestin, β-tubulin III, and MAP2-by the cells cultured on these samples. In comparison with the control group, samples 1 and 2 exhibited significant increases in Nestin marker expression, indicating early stages of neuronal differentiation, while β-tubulin III expression was significantly reduced and MAP2 expression remained statistically unchanged. In contrast, sample 3 did not display a statistically significant upturn in Nestin maker expression, while showcasing remarkable increases in the expression of both MAP2 and β-tubulin III, as markers of the end stages of differentiation, leading to postmitotic neurons. These results could be attributed to the higher electroconductivity of S3 compared to other samples. Our findings highlight the biomimetic potential of the prepared scaffolds for neural repair, illustrating their effectiveness in guiding stem cell differentiation toward a neural lineage.
PubMed: 38959871
DOI: 10.1088/2057-1976/ad5e84