The dual function of calcium ion in fruit edible coating: Regulating polymer internal crosslinking state and improving fruit postharvest quality

The edible coating is proved to be a convenient approach for fruit preservation. Among these published explorations, naturally sourced macromolecules and green crosslinking strategies gain attention. This work centers on edible coatings containing Ca2+ as crosslinker for the first time, delving into crosslinking mechanisms, include alginate, chitosan, Aloe vera gel, gums, etc. Additionally, the crucial functions of Ca2+ in fruit's quality control are also elaborated in-depth, involving cell wall, calmodulin, antioxidant, etc. Through a comprehensive review, it becomes evident that Ca2+ plays a dual role in fruit edible coating. Specifically, Ca2+ constructs a three-dimensional dense network structure with polymers through ionic bonding. Moreover, Ca2+ acts directly with cell wall to maintain fruit firmness and serve as a second messenger to participate secondary physiological metabolism. In brief, coatings containing Ca2+ present remarkable effects in preserving fruit and this work may provide guidance for Ca2+ related fruit preservation coatings.

Quick synthesis of CoFe-PBA@GO with electrochemical method as a novel, sensitive, and degradable nanocomposite applied in nanofibers for triazole extraction before HPLC-UV analysis

Today, the wide use of triazole fungicides due to environmental damage and its side effects has raised global concern. Hence, in this research, poly-vinyl alcohol/polyacrylic-acid/CoFe-PBA@GO electrospun nanofiber was synthesized and applied as effective, degradable, and novel adsorbent at pipette-tip microextraction (PT-μSPE) method for the rapid and concurrent extraction of five of triazole fungicides in fruit and vegetable samples prior to quantitative analysis by high-performance liquid chromatography-ultraviolet. The incorporation of CoFe-PBA@GO with superporous structure and abundant functional groups in a polymer medium improves the extraction efficiency of nanofibers due to hydrogen bonding and π-π interactions formed between analytes and synthesized nano-adsorbent. Various important elements that affect the extraction yield of the target analytes were optimized utilizing a time-variable approach. Under the optimum conditions, dynamic range was attained in the range of 0.3-900.0 ng/mL with correlation coefficients ≥ 0.999. The identification limit of the PT-μSPE-HPLC-UV method ranged from 0.1 to 0.3 ng/mL.

Construction of magnetic azo-linked porous polymer for highly-efficient enrichment and separation of phenolic endocrine disruptors from environmental water and fish

Developing effective methods for highly sensitive detection of phenolic endocrine disruptors (EDCs) is especially urgent. Herein, a magnetic hydroxyl-functional porous organic polymer (M-FH-POP) was facilely synthesized by green diazo-couple reaction using basic fuchsin and hesperetin as monomer for the first time. M-FH-POP delivered superior adsorption performance for phenolic EDCs. The adsorption mechanism was hydrogen bonds, hydrophobic interaction and π-π interplay. With M-FH-POP as adsorbent, a magnetic solid phase extraction method was established for extracting trace phenolic EDCs (bisphenol A, 4-tert-butylphenol, bisphenol F and bisphenol B) in water and fish before ultra-high performance liquid chromatography tandem mass spectrometry analysis. The method displayed low detection limit (S/N = 3) of 0.05-0.15 ng mL-1 for water and 0.08-0.3 ng g-1 for fish. The spiked recoveries were 88.3 %-109.8 % with the relative standard deviations of 2.4 %-6.4 %. The method offers a new strategy for sensitive determination of phenolic EDCs in water and fish samples.

Reduced graphene oxide-functionalized polymer microneedle for continuous and wide-range monitoring of lactate in interstitial fluid

Despite substantial developments in minimally invasive lactate monitoring microneedle electrodes, most such electrode developments have focused on either sensitivity or invasiveness while ignoring a wide range of detection, which is the most important factor in measuring the normal range of lactate in interstitial fluid (ISF). Herein, we present a polymer-based planar microneedle electrode fabrication using microelectromechanical and femtosecond laser technology for the continuous monitoring of lactate in ISF. The microneedle is functionalized with two-dimensional reduced graphene oxide (rGO) and electrochemically synthesized platinum nanoparticles (PtNPs). A particular quantity of Nafion (1.25 wt%) is applied on top of the lactate enzyme to create a diffusion-controlled membrane. Due to the combined effects of the planar structure of the microneedle, rGO, and membrane, the biosensor exhibited excellent linearity up to 10 mM lactate with a limit of detection of 2.04 μM, high sensitivity of 43.96 μA mM-1cm-2, a reaction time of 8 s and outstanding stability, selectivity, and repeatability. The feasibility of the microneedle is evaluated by using it to measure lactate concentrations in artificial ISF and human serum. The results demonstrate that the microneedle described here has great potential for use in real-time lactate monitoring for use in sports medicine and treatment.

Fabrication of a bio-based polymer adsorbent and its application for extraction and determination of glycosides from Huangqi Liuyi decoction

Huangqi Liuyi Decoction, a famous classical Chinese prescription, shows significant curative effect on diabetes and its complications, in which calycosin-7-glucoside, liquiritin and glycyrrhizic acid are the main components that playing these mentioned pharmacological activity, under the synergistic action of various other ingredients in the decoction. However, there are significant differences in the content of active compounds in Chinese medicinal materials, which mainly due to origin, picking seasons, and processing methods. Hence, the accurate content of the glycosides is the prerequisite for ensuring the pharmacological efficacy. Aiming at establishing an efficient extraction and determination method for accurate quantitative analysis of calycosin-7-glucoside, liquiritin and glycyrrhizic acid in Huangqi Liuyi Decoction, an on line solid-phase extraction-high-performance liquid chromatography method was developed, using a homemade bio-based monolithic adsorbent. The bio-based adsorbent was prepared in a stainless steel tube, using bio-monomers of methyleugenol and S-allyl-L-cysteine, which effectively reduced the dependence of the polymer field on non-renewable fossil resources and reduced carbon emissions. Furthermore, the prepared adsorbent owned abundant chemical groups, which can produce interactions of hydrogen bond, dipole-dipole, π-π and hydrophobic force with the target glycosides, thus improving the specific recognition ability of the adsorbent. The experiments were carried out on an LC-3000 HPLC instrument with a six-way valve. Methodology validation indicates that the recovery is in the range of 97.0%-103.4% with the RSD in the range of 1.6%-4.0%, due to the specific selectivity of the bio-based monolithic adsorbent for these three glycosides, and good matrix-removal ability for Huangqi Liuyi decoction. The limit of detection is 0.17, 0.50 and 0.33 μg/mL for calycosin-7-glucoside, liquiritin and glycyrrhizic acid, respectively, and the limit of quantitation is 0.50, 1.50 and 1.00 μg/mL, respectively, with the linear range of 2-200 μg/mL for calycosin-7-glucoside, and 5-500 μg/mL for liquiritin and glycyrrhizic acid. The present work provided a simple and efficient method for the extraction and determination of glycosides in complex medicinal plants.

Polycarbonate Ultracentrifuge Tube Re-use in Proteomic Analyses of Extracellular Vesicles

Single-use laboratory plastics exacerbate the pollution crisis and contribute to consumable costs. In extracellular vesicle (EV) isolation, polycarbonate ultracentrifuge (UC) tubes are used to endure the associated high centrifugal forces. EV proteomics is an advancing field and validated re-use protocols for these tubes are lacking. Re-using consumables for low-yield protein isolation protocols and downstream proteomics requires reagent compatibility with mass spectroscopy acquisitions, such as the absence of centrifuge tube-derived synthetic polymer contamination, and sufficient removal of residual proteins. This protocol describes and validates a method for cleaning polycarbonate UC tubes for re-use in EV proteomics experiments. The cleaning process involves immediate submersion of UC tubes in H2O to prevent protein drying, washing in 0.1% sodium dodecyl sulfate (SDS) detergent, rinsing in hot tap water, demineralized water, and 70% ethanol. To validate the UC tube re-use protocol for downstream EV proteomics, used tubes were obtained following an experiment isolating EVs from cardiovascular tissue using differential UC and density gradient separation. Tubes were cleaned and the experimental process was repeated without EV samples comparing blank never-used UC tubes to cleaned UC tubes. The pseudo-EV pellets obtained from the isolation procedures were lysed and prepared for liquid chromatography-tandem mass spectrometry using a commercial protein sample preparation kit with modifications for low-abundance protein samples. Following cleaning, the number of identified proteins was reduced by 98% in the pseudo-pellet versus the previous EV isolation sample from the same tube. Comparing a cleaned tube against a blank tube, both samples contained a very small number of proteins (≤20) with 86% similarity. The absence of polymer peaks in the chromatograms of the cleaned tubes was confirmed. Ultimately, the validation of a UC tube cleaning protocol suitable for the enrichment of EVs will reduce the waste produced by EV laboratories and lower the experimental costs.

High prevalence of microplastics in the digestive tract of Scyliorhinus canicula (Linneaus, 1758) shows the species biomonitoring potential

Plastic pollution is widespread in oceans and the ingestion of plastic by marine organisms is causing concern about potential adverse effects. The purpose of this study was to analyze the different types of plastics in the digestive tract of female small-spotted catshark (Scyliorhinus canicula). An alkaline digestion method using 10 % potassium hydroxide (KOH), was used. The samples were filtered and visually observed to classify the plastics according to size, shape, and color. Raman spectroscopy was further employed to identify the polymer types. The study found the presence of plastics in 89.5 % of the 200 females analyzed, including 10 polymers, with polystyrene (PS), polyamide-6 (PA6), polyvinyl chloride (PVC), and silicone rubber (SR) being the most common. The polymers identified largely reflect the results of similar studies in the marine environment and were similar to global polymer diversity of microplastics, which highlights the potential of S. canicula females for biomonitoring microplastic pollution.

Organic-inorganic composite hydrogels: compositions, properties, and applications in regenerative medicine

Hydrogels, formed from crosslinked hydrophilic macromolecules, provide a three-dimensional microenvironment that mimics the extracellular matrix. They served as scaffold materials in regenerative medicine with an ever-growing demand. However, hydrogels composed of only organic components may not fully meet the performance and functionalization requirements for various tissue defects. Composite hydrogels, containing inorganic components, have attracted tremendous attention due to their unique compositions and properties. Rigid inorganic particles, rods, fibers, etc., can form organic-inorganic composite hydrogels through physical interaction and chemical bonding with polymer chains, which can not only adjust strength and modulus, but also act as carriers of bioactive components, enhancing the properties and biological functions of the composite hydrogels. Notably, incorporating environmental or stimulus-responsive inorganic particles imparts smartness to hydrogels, hence providing a flexible diagnostic platform for in vitro cell culture and in vivo tissue regeneration. In this review, we discuss and compare a set of materials currently used for developing organic-inorganic composite hydrogels, including the modification strategies for organic and inorganic components and their unique contributions to regenerative medicine. Specific emphasis is placed on the interactions between the organic or inorganic components and the biological functions introduced by the inorganic components. The advantages of these composite hydrogels indicate their potential to offer adaptable and intelligent therapeutic solutions for diverse tissue repair demands within the realm of regenerative medicine.

Structural and mechanical roles of wood polymer assemblies in softwood revealed by gradual removal of polysaccharides or lignin

A deep understanding of the inherent roles of wood polymers such as cellulose, hemicelluloses, and lignin in the hierarchical structure of wood is of key importance for advancing functional wood-based materials but is currently lacking. To address this gap, we clarified the underexplored contributions of wood polymer assemblies to the structural support and compressive properties of wood by chemically removing polysaccharides or lignin from wood blocks of a conifer Cryptomeria japonica. Compositional and structural evaluations revealed that cellulose, hemicelluloses, and lignin contributed to the dimensional stability of wood, especially that the polysaccharide network at cell corners sustained the honeycomb cell structure. Wood polymer assemblies featuring the anatomical structure of wood were also evaluated in terms of compressive properties. The modulus and strength reflected the density and anisotropy, whereas fracture behavior was well characterized by each wood polymer assembly through the classification of stress-strain curves based on principal component analysis. The difference in fracture behaviors indicated that the rigid lignin and flexible cellulose assemblies, possibly mediated by hemicelluloses, complementarily determine the unique compressive response of wood. These findings enable the adjustment of wood functionality and the selection of composite components for wood modification while inspiring the development of novel wood applications.

Extraction of lignocellulosic fiber and cellulose microfibrils from agro waste-palmyra fruit peduncle: Water retting, chlorine-free chemical treatments, physio-chemical, morphological, and thermal characterization

In this paper, lignocellulosic fibers and cellulose microfibrils (CMFs) were extracted from palmyra fruit peduncle waste and investigated as naturally derived cellulosic materials for their potential use as reinforcement materials in composite applications. The physicochemical, mechanical, and thermal properties of the extracted fiber were studied. Physical and morphological analysis results revealed an extracted fiber diameter of 82.5 μm with a very rough surface, providing excellent interfacial bonding performance with the polymer matrix. Chemical, mechanical, and thermal results showed that the fibers consist mainly of cellulose as their crystallized phase, with a cellulose content of 56.5 wt% and a tensile strength of 693.3 MPa, along with thermal stability up to 252 °C. The chemically extracted CMFs exhibit a short, rough-surfaced, cylindrical cellulose structure with a diameter range of 10-15 μm. These CMFs demonstrate excellent thermal stability, withstanding temperatures up to 330 °C. Furthermore, the formation of CMFs is evident from a substantial increase in the crystallinity index, which increased from 58.2 % in the raw fibers to 78.2 % in the CMFs. FT-IR analysis further confirms the successful removal of non-cellulosic materials through chlorine-free chemical treatments. These findings strongly support the potential use of extracted fibers and CMFs as reinforcement materials in polymers.

Quantitation of polyethylene glycol by size exclusion chromatography with charged aerosol, differential refractive index, and multi-angle light scattering detectors

Polyethylene glycol (PEG) has found tremendous applications in pharmaceutical products and has played a critical role in PEGylated drug modalities to improve pharmacokinetic properties and biological efficacy. The characterization and quantitation of PEGs are essential to control manufacture process and drug product quality. However, the assay value of PEG could change dramatically depending on the structures of the PEG and the detection techniques used. In this study, we developed a size exclusion chromatographic (SEC) method for quantitative PEG analysis, and we systematically evaluated the performance of three online detectors with different operating principles: a charged aerosol detector (CAD), a differential refractive index (dRI) detector, and a multi-angle light scattering detector (MALS). Fourteen PEG compounds covering a wide range of molecular weight (MW, 1 - 40 kDa) and molecular architectures (linear, branched, Y-shaped and multi-arm geometries) were evaluated by these three detection techniques. Our study revealed that the dRI showed the most universal responses among all the PEGs regardless of their molecular weight or geometries. In the contrast, CAD and MALS detector showed MW-dependent and semi-universal geometry-dependent responses. Another key finding is that the relative response factor for each multi-arm PEG in the CAD and the MALS were inversely correlated, suggesting both can be applied to qualitatively assess polymers of different architectures, including the ones with subtle differences in their core structures. The comparison of the three detectors not only provides the fundamental and comprehensive understanding of PEG quantitation but also enables the process development and control of high-quality PEGs in producing PEGylated therapeutics in the pharmaceutical industry.

Analysis of microplastics in ships ballast water and its ecological risk assessment studies from the Persian Gulf

Transport of ballast water is considered a significant vector for dispersion of different pollutants, including microplastics (MPs), throughout the world's oceans. However, there is limited information on MPs in ballast water. Size distribution, polymer type, and ecological risks of MPs in ballast water were investigated for the first time in this study. The mean levels of MPs in ballast water and seawater samples were 12.53 and 11.80 items/L, respectively. MPs with a size category of 50-300 μm was the most abundant. Fiber, black, and polycarbonate (PC) were the predominant shape, color, and polymer type of identified MPs in ballast water and seawater, respectively. The pollution load index (PLI), hazard index (HI), and risk quotient (RQ) indicated high levels of MP pollution, potentially indicating an ecological risk. These findings increase our understanding of the major sources (such as ballast water), transportation routes, and related ecological risks of MPs to marine ecosystems.

Ultra-high-performance liquid chromatography with tandem mass spectrometry method for cellular toxicity and pharmacokinetic study of PEG1K polymers

Polyethylene glycol (PEG) is one of the most commonly used polymers in drug delivery systems. The investigation of the pharmacokinetic behavior of PEG is important for revealing the toxicity and efficiency of PEG-related Nano-drug delivery systems. A high through-put and selective ultra-high-performance liquid chromatography with tandem mass spectrometry (UHPLC-MS/MS) method coupled with collision-induced dissociation (CID) in source technique was developed and validated to determine PEG1K polymers in cellular samples in this study. The countless precursor ions of PEG1K are dissociated in the source to generate numerous product ions which have different numbers of subunits. The transition of [M+H]+ precursor ions → product ions at m/z 177.1 (four subunits)→89.1 (two subunits) was selected to determine PEG1K due to its high sensitivity. The UHPLC-MS/MS method coupled with CID in the source showed good linearity over the range of 0.1-10 μg/mL. Intra-day and inter-day accuracies and precisions of the assay were all within ± 12.39%. The assay was successfully applied to a cellular pharmacokinetic study of PEG1K in human breast cancer cells. The cytotoxicity of PEG1K polymers was also studied and the results indicated that the cytotoxicity of PEG1K was not significant in the range of 5-1200 μg/mL.

A chitin-based magnetic hyper-cross-linked polymer for highly efficient enrichment of neonicotinoids in lemon juice and tomatoes

A chitin-based magnetic hyper-cross-linked polymer (labeled as Ch-MHCP) has been successfully synthesized and utilized for highly-effective solid-phase extraction of neonicotinoid insecticides (NEOs). The extraction capability of Ch-MHCP for four common NEOs is higher than that of four commercial sorbents including octadecyl-silane C18, oasis hydrophilic/lipophilic balanced sorbent, oasis mixed anion sorbent and poly-phenylacetic mixed anion sorbent. The large number of hydroxyl and amide groups as well as benzene rings in Ch-MHCP allow the H-bond and π-π* interaction to be the principal adsorption mechanism of Ch-MHCP for NEOs. Besides, polar interaction was also involved in the adsorption process. In combination of Ch-MHCP based extraction technique with high-performance liquid chromatography, a novel analytical method for sensitive detection of NEOs in lemon juice and tomatoes has been established. At optimal conditions, wide linear ranges were obtained to be 0.20-100 ng mL-1 for lemon juice and 0.80-1000 ng g-1 for tomatoes. The detection limits were 0.06-0.12 ng mL-1 for lemon juice and 0.24-0.60 ng g-1 for tomatoes. This work not only provides a powerful tool for simultaneously detecting four NEOs in lemon juice and tomatoes, but also offers a new insight into the preparation of bio-based magnetic sorbents for adsorption/removal of pollutants.

Microtubule rescue control by drugs and MAPs examined with in vitro pedestal assay

Microtubules are essential cytoskeletal polymers, which exhibit stochastic transitions between assembly and disassembly, known as catastrophes and rescues. Understanding of catastrophes, rescues, and their control by drugs and microtubule associated proteins (MAPs) has been informed by in vitro reconstitutions of microtubule dynamics. In such experiments microtubules are typically observed on a flat surface of the coverslip. In contrast, we have recently proposed a modified setup in which microtubules assemble from stabilized seeds, overhanging from microfabricated pedestals, so that their dynamic extensions are fully isolated from contact with the coverslip. This assay allows to eliminate potential artifacts, which may substantially affect the frequency of microtubule rescues in vitro. Here we use the pedestal assay to study the sensitivity of microtubules to paclitaxel, one of the best-known inhibitors of microtubule dynamics. By comparing observations in the conventional and the pedestal assays, we find that microtubule dynamics are substantially more sensitive to paclitaxel when the polymers can contact the coverslip. We interpret this as a consequence of the coverslip-induced microtubule assembly perturbation, leading to formation of lattice with defects, and thereby enhancing the efficiency of paclitaxel binding to microtubules in the conventional assay. To test this idea, we use vinblastine, another small-molecule inhibitor, which had been previously shown to cause microtubule growth perturbations. We find that in the pedestal assay vinblastine sensitizes microtubules to paclitaxel to the level, observed in the conventional assay. Interestingly, a minimal fragment of MAP called CLASP2, a previously characterized rescue factor, has a strong effect on microtubule rescues, regardless of the type of assay. Overall, our study underscores the role of microtubule damage in promoting rescues and highlights the utility of the in vitro pedestal assay to study microtubule dynamics modulation by tubulin inhibitors and MAPs.

NMR-Based Tastant Polymer Interaction Studies and the Influence on the Taste Perception of Red Wine

Using a quantitative 1H NMR-based approach, molecular interactions between key taste active compounds and high-molecular-weight (HMW) polymers were directly investigated in red wine. Analysis of qualitative and quantitative 1H NMR spectra over time allowed a distinction of three interaction scenarios: (i) no interactions for flavon-3-ol glycosides, ellagitannins, carbohydrates, and amino acids; (ii) changes in the chemical shift to lower frequencies for flavan-3-ols and phenolic acid ethyl esters; and (iii) changes in the chemical shift to higher frequencies for phenolic acids, organic acids, inorganic salts, and alditols. Additionally, using liquid chromatography-tandem mass spectrometry (LC-MS/MS), quantitative 1H nuclear magnetic resonance (qHNMR), and high-performance ion chromatography (HPIC), a taste reconstitution model of Primitivo red wine was established for the first time. Human sensory experiments with the new taste recombinant and different HMW fractions demonstrated the influence of the tastant polymer interactions on the sour and salty taste perception of red wine and the intrinsic bitter and astringent taste of the polymers. Further, the influence of the molecular weight cutoff (MWCO) of the polymers and the pH value on the tastant polymer interactions was analyzed. Especially, the HMW fractions 30-50 kDa and >50 kDa caused strong shifts to lower and higher frequencies, respectively. NMR-based interaction studies at different pH values revealed a maximum of interactions at pH 4.0. Based on these results, flavor changes in red wine caused by tastant polymer interactions can be predicted on a molecular level in the future.

Quantitative and qualitative impacts of nitric acid digestion on microplastic identification via FTIR and Raman spectroscopy, implications for environmental samples

Quantification and characterization of microplastics, synthetic polymers less than 5 mm in diameter, requires extraction methods that can reduce non-plastic debris without loss or alteration of the polymers. Nitric acid has been used to extract plastic particles from zooplankton and other biota because it completely digests tissue and exoskeletons, thus reducing interferences. While the impact of acid digestion protocols on several polymers has been demonstrated, advice for quantifying microplastic and interpreting their spectra following nitric acid digestion is lacking. Fourier transform infrared (FTIR) and/or Raman spectroscopy was performed on plastics from > 50 common consumer products (including a variety of textiles) pre- and post-nitric acid treatment. The percent match and assigned polymer were tabulated to compare the accuracy of spectral identification before and after nitric acid digestion via two open spectral analysis software. Nylon-66, polyoxymethylene, polyurethane, polyisoprene, nitrile rubber, and polymethyl methacrylate had ≥ 90% mass loss in nitric acid. Other less-impacted polymers changed color, morphology, and/or size following digestion. Thus, using nitric acid digestion for microplastic extraction can impact our understanding of the particle sizes and morphologies ingested in situ. Spectral analysis results were compiled to understand how often (1) the best-hit matches were correct (30-60% of spectra), (2) the best-hit matches exceeding the (arbitrary) threshold of 65% match were correct (53-78% of spectra), and (3) the best-hit matches for anthropogenic polymers were incorrectly identified as natural polymers (12-15% of spectra). Based on these results, advice is provided on how nitric acid digestion can impact microplastics as well as spectral interpretation.

Preparation of COPs Mixed Matrix Membrane for Sensitive Determination of Six Sulfonamides in Human Urine

In this study, TpDMB-COPs, a specific class of covalent organic polymers (COPs), was synthesized using Schiff-base chemistry and incorporated into a polyvinylidene fluoride (PVDF) polymer for the first time to prepare COPs mixed matrix membranes (TpDMB-COPs-MMM). A membrane solid-phase extraction (ME) method based on the TpDMB-COPs-MMM was developed to extract trace levels of six sulfonamides from human urine identified by high-performance liquid chromatography (HPLC). The key factors affecting the extraction efficiency were investigated. Under the optimum conditions, the proposed method demonstrated an excellent linear relationship in the range of 3.5-25 ng/mL (r2 ≥ 0.9991), with the low limits of detection (LOD) between 1.25 ng/mL and 2.50 ng/mL and the limit of quantification (LOQ) between 3.50 ng/mL and 7.00 ng/mL. Intra-day and inter-day accuracies were below 5.0%. The method's accuracy was assessed by recovery experiments using human urine spiked at three levels (7-14 ng/mL, 10-15 ng/mL, and 16-20 ng/mL). The recoveries ranged from 87.4 to 112.2% with relative standard deviations (RSD) ≤ 8.7%, confirming the applicability of the proposed method. The developed ME method based on TpDMB-COPs-MMM offered advantages, including simple operation, superior extraction affinity, excellent recycling performance, and easy removal and separation from the solution. The prepared TpDMB-COPs-MMM was demonstrated to be a promising adsorbent for ME in the pre-concentration of trace organic compounds from complex matrices, expanding the application of COPs and providing references for other porous materials in sample pre-treatment.

Multifilament Collagen Fiber Bundles with Tendon-like Structure and Mechanical Performance

Collagen multifilament bundles comprised of thousands of monofilaments are prepared by multipin contact drawing of an entangled polymer solution consisting of collagen and poly(ethylene oxide) (PEO). The multifilament bundles are hydrated in graded concentrations of PEO and phosphate buffered saline (PBS) to promote assembly of collagen fibrils within each monofilament while preserving the structure of the multifilament bundle. Multiscale structural characterization reveals that the hydrated multifilament bundle contains properly folded collagen molecules packed in collagen fibrils containing microfibrils, staggered by exactly one-sixth of the microfibril D-band spacing to produce a periodicity of 11 nm. Sequence analysis predicts that in this structure, phenylalanine residues are close enough within and between microfibrils to become ultraviolet C (UVC) crosslinked. In agreement with this analysis, the ultimate tensile strength (UTS) and Young's modulus of the hydrated collagen multifilament bundles crosslinked by UVC radiation increase nonlinearly with total UVC energy to reach values in the range of native tendons without damage to the collagen molecules. This fabrication method recapitulates the structure of a tendon across multiple length scales and offers tunability in tensile properties using only collagen molecules and no other chemical additives in addition to PEO, which is almost entirely removed during the hydration process.

In Situ Covalent Reinforcement of a Benzene-1,3,5-Tricarboxamide Supramolecular Polymer Enables Biomimetic, Tough, and Fibrous Hydrogels and Bioinks

Synthetic hydrogels often lack the load-bearing capacity and mechanical properties of native biopolymers found in tissue, such as cartilage. In natural tissues, toughness is often imparted via the combination of fibrous noncovalent self-assembly with key covalent bond formation. This controlled combination of supramolecular and covalent interactions remains difficult to engineer, yet can provide a clear strategy for advanced biomaterials. Here, a synthetic supramolecular/covalent strategy is investigated for creating a tough hydrogel that embodies the hierarchical fibrous architecture of the extracellular matrix (ECM). A benzene-1,3,5-tricarboxamide (BTA) hydrogelator is developed with synthetically addressable norbornene handles that self-assembles to form a and viscoelastic hydrogel. Inspired by collagen's covalent cross-linking of fibrils, the mechanical properties are reinforced by covalent intra- and interfiber cross-links. At over 90% water, the hydrogels withstand up to 550% tensile strain, 90% compressive strain, and dissipated energy with recoverable hysteresis. The hydrogels are shear-thinning, can be 3D bioprinted with good shape fidelity, and can be toughened via covalent cross-linking. These materials enable the bioprinting of human mesenchymal stromal cell (hMSC) spheroids and subsequent differentiation into chondrogenic tissue. Collectively, these findings highlight the power of covalent reinforcement of supramolecular fibers, offering a strategy for the bottom-up design of dynamic, yet tough, hydrogels and bioinks.

Fabrication and application of Zn5 functionalized copolymer monolithic column for pipette tip micro-solid phase extraction of 4 polycyclic aromatic hydrocarbons in edible oil

The contamination of polycyclic aromatic hydrocarbons (PAHs) in edible oil is a health threat. Thus, trace analysis of PAHs is of high necessity. Based on the efficient adsorption of PAHs on Zn₅ metal cluster, a Zn₅ functionalized copolymer monolithic column was rationally designed for pipette tip micro-solid phase extraction (μ-SPE). The modified Zn₅ improved the adsorption selectivity and capacity of the monolith for naphthalene, phenanthrene, fluoranthene and pyrene. Chemical doping and copolymerization stabilized the monolith with a long life. Under optimal extraction conditions, a μ-SPE-high performance liquid chromatography with ultraviolet detector method was established for the detection of 4 PAHs in edible oils. The method yielded detection ranges of 0.15-250 μg L^-1 (R² > 0.997), detection limits of 0.050-1.5 μg L^-1, satisfactory recoveries (86.3-101.5 %), and high precisions (RSDs < 7.9 %). The results indicated that the Zn₅ functionalized copolymer monolithic column was an ideal separation medium for the detection of PAHs residues in edible oils.

The improvement of heavy metals removal by wood membrane in drinking water treatment: Comparison with polymer membrane and associated mechanism

The application of commercial membranes is limited by the secondary pollution such as the usage of toxic chemicals for the membrane preparation and the disposal of aged membranes. Therefore, the green and environmentally friendly membranes are extremely promising for the sustainable development of membrane filtration in water treatment. In this study, the comparison of wood membrane with the pore size of tens microns (μm) and polymer membrane with the pore size of 0.45 μm was made to study the heavy metals removal in drinking water treatment by gravity-driven membrane (GDM) filtration system, and there was an improvement in the removal of Fe, Cu and Mn by wood membrane. The sponge-like structure of fouling layer for wood membrane made the retention time of heavy metals prolonged in contrast to the cobweb-like structure of polymer membrane. The carboxylic group (-COOH) content of fouling layer for wood membrane was greater than that for polymer membrane. Additionally, the population abundance of heavy metal-capturing microbes on the surface of wood membrane was higher compared with polymer membrane. The wood membrane provides a promising route to producing facile, biodegradable and sustainable membrane as a green alternative to polymer membranes in heavy metal removal from drinking water.

Cooking food in microwavable plastic containers: in situ formation of a new chemical substance and increased migration of polypropylene polymers

Microwavable plastic food containers can be a source of toxic substances. Plastic materials such as polypropylene polymers are typically employed as safe materials in food packaging, but recent research demonstrates the migration of plastic substances or their by-products to food simulants, to foodstuff, and, more recently, to the human body through food consumption. However, a thorough evaluation of foodstuff in food contact materials under cooking conditions has not yet been undertaken. Here we show for the first time that plastic migrants present in food contact materials can react with natural food components resulting in a compound that combines a UV-photoinitiator (2-hydroxy-2-methyl-1-phenylpropan-1-one) with maltose from potato starch; this has been identified after cooking potatoes in microwavable plastic food containers. Additionally, polypropylene glycol substances have been found to transfer into food through microwave cooking. Identifying these substances formed in situ requires state-of-the-art high-resolution mass spectrometry instrumentation and metabolomics-based strategies.

Additives in polypropylene and polylactic acid food packaging: Chemical analysis and bioassays provide complementary tools for risk assessment

Plastic food packaging represents 40 % of the plastic production worldwide and belongs to the 10 most commonly found items in aquatic environments. They are characterized by high additives contents with >4000 formulations available on the market. Thus they can release their constitutive chemicals (i.e. additives) into the surrounding environment, contributing to chemical pollution in aquatic systems and to contamination of marine organism up to the point of questioning the health of the consumer. In this context, the chemical and toxicological profiles of two types of polypropylene (PP) and polylactic acid (PLA) food packaging were investigated, using in vitro bioassays and target gas chromatography mass spectrometry analyses. Plastic additives quantification was performed both on the raw materials, and on the material leachates after 5 days of lixiviation in filtered natural seawater. The results showed that all samples (raw materials and leachates) contained additive compounds (e.g. phthalates plasticizers, phosphorous flame retardants, antioxidants and UV-stabilizers). Differences in the number and concentration of additives between polymers and suppliers were also pointed out, indicating that the chemical signature cannot be generalized to a polymer and is rather product dependent. Nevertheless, no significant toxic effects was observed upon exposure to the leachates in two short-term bioassays targeting baseline toxicity (Microtox® test) and Pacific oyster Crassostrea gigas fertilization success and embryo-larval development. Overall, this study demonstrates that both petrochemical and bio-based food containers contain harmful additives and that it is not possible to predict material toxicity solely based on chemical analysis. Additionally, it highlights the complexity to assess and comprehend the additive content of plastic packaging due to the variability of their composition, suggesting that more transparency in polymer formulations is required to properly address the risk associated with such materials during their use and end of life.

Optimization of non-equilibrium self-assembly protocols using Markov state models

The promise of self-assembly to enable the bottom-up formation of materials with prescribed architectures and functions has driven intensive efforts to uncover rational design principles for maximizing the yield of a target structure. Yet, despite many successful examples of self-assembly, ensuring kinetic accessibility of the target structure remains an unsolved problem in many systems. In particular, long-lived kinetic traps can result in assembly times that vastly exceed experimentally accessible timescales. One proposed solution is to design non-equilibrium assembly protocols in which system parameters change over time to avoid such kinetic traps. Here, we develop a framework to combine Markov state model (MSM) analysis with optimal control theory to compute a time-dependent protocol that maximizes the yield of the target structure at a finite time. We present an adjoint-based gradient descent method that, in conjunction with MSMs for a system as a function of its control parameters, enables efficiently optimizing the assembly protocol. We also describe an interpolation approach to significantly reduce the number of simulations required to construct the MSMs. We demonstrate our approach with two examples; a simple semi-analytic model for the folding of a polymer of colloidal particles, and a more complex model for capsid assembly. Our results show that optimizing time-dependent protocols can achieve significant improvements in the yields of selected structures, including equilibrium free energy minima, long-lived metastable structures, and transient states.

Use of QuEChERS as a manual and automated high-throughput protocol for investigating environmental matrices

Environmental pollution has strong links to adverse human health outcomes with risks of pollution through production, use, ineffective wastewater (WW) remediation, and/or leachate from landfill. 'Fit-for-purpose' monitoring approaches are critical for better pollution control and mitigation of harm, with current sample preparation methods for complex environmental matrices typically time-consuming and labour intensive, unsuitable for high-throughput screening. This study has shown that a modified 'Quick Easy Cheap Effective Rugged and Safe' (QuEChERS) sample preparation is a viable alternative for selected environmental matrices required for pollution monitoring (e.g. WW effluent, treated sludge cake and homogenised biota tissue). As a manual approach, reduced extraction times (hours to ∼20 min/sample) with largely reproducible (albeit lower) recoveries of a range of pharmaceuticals and biocidal surfactants have been reported. Its application has shown clear differentiation of matrices via chemometrics, and the measurement of pollutants of interest to the UK WW industry at concentrations significantly above suggested instrument detection limits (IDL) for sludge, indicating insufficient removal and/or bioaccumulation during WW treatment. Furthermore, new pollutant candidates of emerging concern were identified - these included detergents, polymers and pharmaceuticals, with quaternary ammonium compound (QAC) biocides observed at 2.3-70.4 mg/kg, and above levels associated with priority substances for environmental quality regulation (EQSD). Finally, the QuEChERS protocol was adapted to function as a fully automated workflow, further reducing the resource to complete both the preparation and analysis to <40 min. This operated with improved recovery for soil and biota (>62%), and when applied to a largely un-investigated clay matrix, acceptable recovery (88.0-131.1%) and precision (≤10.3% RSD) for the tested pharmaceuticals and biocides was maintained. Therefore, this preliminary study has shown the successful application of a high-throughput QuEChERS protocol across a range of environmental solids for potential deployment in a regulated laboratory.

Secondary structure and 1H, 15 N & 13C resonance assignments of the periplasmic domain of OutG, major pseudopilin from Dickeya dadantii type II secretion system

The ability to interact and adapt to the surrounding environment is vital for bacteria that colonise various niches and organisms. One strategy developed by Gram-negative bacteria is to secrete exoprotein substrates via the type II secretion system (T2SS). The T2SS is a proteinaceous complex spanning the bacterial envelope that translocates folded proteins such as toxins and enzymes from the periplasm to the extracellular milieu. In the T2SS, a cytoplasmic ATPase elongates in the periplasm the pseudopilus, a non-covalent polymer composed of protein subunits named pseudopilins, and anchored in the inner membrane by a transmembrane helix. The pseudopilus polymerisation is coupled to the secretion of substrates. The T2SS of Dickeya dadantii secretes more than 15 substrates, essentially plant cell wall degrading enzymes. In D. dadantii, the major pseudopilin or the major subunit of the pseudopilus is called OutG. To better understand the mechanism of secretion of these numerous substrates via the pseudopilus, we have been studying the structure of OutG by NMR. Here, as the first part of this study, we report the ¹H, ¹⁵N and ¹³C backbone and sidechain chemical shift assignment of the periplasmic domain of OutG and its NMR derived secondary structure.

An Electret-Powered Skin-Attachable Auditory Sensor that Functions in Harsh Acoustic Environments

Auditory sensors have shortcomings with respect to not only personalization with wearability and portability but also detecting a human voice clearly in a noisy environment or when a mask covers the mouth. In this work, an electret-powered and hole-patterned polymer diaphragm is exploited into a skin-attachable auditory sensor. The optimized charged electret diaphragm induces a voltage bias of >400 V against the counter electrode, which reduces the necessity of a bulky power source and enables the capacitive sensor to show high sensitivity (2.2 V Pa^-1 ) with incorporation of an elastomer nanodroplet seismic mass. The sophisticated capacitive structure with low mechanical damping enables a flat frequency response (80-3000 Hz) and good linearity (50-80 dB_SPL ). The hole-patterned electret diaphragms help the skin-attachable sensor detect only neck-skin vibration rather than dynamic air pressure, enabling a person's voice to be detected in a harsh acoustic environment. The sensor operates reliably even in the presence of surrounding noise and when the user is wearing a gas mask. Therefore, the sensor shows strong potential of a communication tool for disaster response and quarantine activities, and of diagnosis tool for vocal healthcare applications such as cough monitoring and voice dosimetry.

Cell compensatory responses of fungi to damage of the cell wall induced by Calcofluor White and Congo Red with emphasis on Sporothrix schenckii and Sporothrix globosa. A review

The cell wall (CW) of fungi exhibits a complex structure and a characteristic chemical composition consisting almost entirely of interacting crystalline and amorphous polysaccharides. These are synthesized by a number of sugar polymerases and depolymerases encoded by a high proportion of the fungal genome (for instance, 20% in Saccharomyces cerevisiae). These enzymes act in an exquisitely coordinated process to assemble the tridimensional and the functional structure of the wall. Apart from playing a critical role in morphogenesis, cell protection, viability and pathogenesis, the CW represents a potential target for antifungals as most of its constituents do not exist in humans. Chitin, β-glucans and cellulose are the most frequent crystalline polymers found in the fungal CW. The hexosamine biosynthesis pathway (HBP) is critical for CW elaboration. Also known as the Leloir pathway, this pathway ends with the formation of UDP-N-GlcNAc after four enzymatic steps that start with fructose-6-phosphate and L-glutamine in a short deviation of glycolysis. This activated aminosugar is used for the synthesis of a large variety of biomacromolecules in a vast number of organisms including bacteria, fungi, insects, crustaceans and mammalian cells. The first reaction of the HBP is catalyzed by GlcN-6-P synthase (L-glutamine:D-fructose-6-phosphate amidotransferase; EC 2.6.1.16), a critical enzyme that has been considered as a potential target for antifungals. The enzyme regulates the amount of cell UDP-N-GlcNAc and in eukaryotes is feedback inhibited by the activated aminosugar and other factors. The native and recombinant forms of GlcN-6-P synthase has been purified and characterized from both prokaryotic and eukaryotic organisms and demonstrated its critical role in CW remodeling and morphogenesis after exposure of some fungi to agents that stress the cell surface by interacting with wall polymers. This review deals with some of the cell compensatory responses of fungi to wall damage induced by Congo Red and Calcofluor White.

One-pot synthesis of brewer's spent grain-supported superabsorbent polymer for highly efficient uranium adsorption from wastewater

High-efficient and fast adsorption of uranium is important to reduce the hazards caused by the uranium contamination of water environment due to the increased human activities. Herein, brewer's spent grain (BSG)-supported superabsorbent polymers (SAP) with different cross-linking densities are prepared as cheap and eco-friendly adsorbents for the first time via one-pot swelling and graft polymerization. A 7 wt% NaOH solution is used to swell BSG before grafting and subsequently neutralize the acrylic acid to control the reaction rate without producing alkaline wastewater. Compared with the traditional methods, swelling improves the grafting density and the utilization of raw materials due to the increased disorder degree of the BSG fibers. This results in the grafting of abundant carboxyl and amide groups onto the BSG backbone, forming a strongly hydrophilic polymer network of the BSG-SAP. Compared with the reference polymers without BSG, BSG-SAP presents higher adsorption capacity and enhanced reusability. The highly cross-linked BSG-SAP (BSG-SAP-H) shows an outstanding adsorption capacity of U(VI) (1465 mg/g at pH₀ = 4.6), a fast adsorption rate (81% of equilibrium adsorption capacity in 15 min), and a high selectivity in the presence of competing ions. Adsorption mechanism studies reveal the involvement of amide groups, a bidentate binding structure between UO₂²⁺ and the carboxyl groups, and a cation exchange between Na⁺ and UO₂²⁺. More importantly, the adsorption capacity of BSG-SAP-H reaches 254.4 mg/g in the fixed-bed column experiment at a low initial concentration (c₀(U) = 30 mg/L) and keeps 80% of the adsorption capacity after four cycles, indicating a great potential for uranium removal from wastewater. This work shows a suitable approach to explore the untreated biomass to prepare SAP with enhanced adsorption performance via a general and low-cost strategy.

Programmable DNA Hydrogels as Artificial Extracellular Matrix

The cell microenvironment plays a crucial role in regulating cell behavior and fate in physiological and pathological processes. As the fundamental component of the cell microenvironment, extracellular matrix (ECM) typically possesses complex ordered structures and provides essential physical and chemical cues to the cells. Hydrogels have attracted much attention in recapitulating the ECM. Compared to natural and synthetic polymer hydrogels, DNA hydrogels have unique programmable capability, which endows the material precise structural customization and tunable properties. This review focuses on recent advances in programmable DNA hydrogels as artificial extracellular matrix, particularly the pure DNA hydrogels. It introduces the classification, design, and assembly of DNA hydrogels, and then summarizes the state-of-the-art achievements in cell encapsulation, cell culture, and tissue engineering with DNA hydrogels. Ultimately, the challenges and prospects for cellular applications of DNA hydrogels are delivered.

LPS O Antigen Plays a Key Role in Klebsiella pneumoniae Capsule Retention

Despite the importance of encapsulation in bacterial pathogenesis, the biochemical mechanisms and forces that underpin retention of capsule by encapsulated bacteria are poorly understood. In Gram-negative bacteria, there may be interactions between lipopolysaccharide (LPS) core and capsule polymers, between capsule polymers with retained acyl carriers and the outer membrane, and in some bacteria, between the capsule polymers and Wzi, an outer membrane protein lectin. Our transposon studies in Klebsiella pneumoniae B5055 identified additional genes that, when insertionally inactivated, resulted in reduced encapsulation. Inactivation of the gene waaL, which encodes the ligase responsible for attaching the repeated O antigen of LPS to the LPS core, resulted in a significant reduction in capsule retention, measured by atomic force microscopy. This reduction in encapsulation was associated with increased sensitivity to human serum and decreased virulence in a murine model of respiratory infection and, paradoxically, with increased biofilm formation. The capsule in the WaaL mutant was physically smaller than that of the Wzi mutant of K. pneumoniae B5055. These results suggest that interactions between surface carbohydrate polymers may enhance encapsulation, a key phenotype in bacterial virulence, and provide another target for the development of antimicrobials that may avoid resistance issues associated with growth inhibition. IMPORTANCE Bacterial capsules, typically comprised of complex sugars, enable pathogens to avoid key host responses to infection, including phagocytosis. These capsules are synthesized within the bacteria, exported through the outer envelope, and then secured to the external surface of the organism by a force or forces that are incompletely described. This study shows that in the important hospital pathogen Klebsiella pneumoniae, the polysaccharide capsule is retained by interactions with other surface sugars, especially the repeated sugar molecule of the LPS molecule in Gram-negative bacteria known as "O antigen." This O antigen is joined to the LPS molecule by ligation, and loss of the enzyme responsible for ligation, a protein called WaaL, results in reduced encapsulation. Since capsules are essential to the virulence of many pathogens, WaaL might provide a target for new antimicrobial development, critical to the control of pathogens like K. pneumoniae that have become highly drug resistant.

Magnetic polymer particles as a highly efficient and facile cleanup adsorbent for multi-pesticide residues analysis in aquatic products

A novel and efficient sample pretreatment procedure using magnetic particles was exploited for the determination of multi-pesticide residues in aquatic products. The magnetic adsorbent was prepared using divinyl benzene and N-vinyl pyrrolidone as functional monomers modified on the Fe₃O₄ @SiO₂. The obtained magnetic adsorbent, octadecylsilane sorbents, and graphitized carbon black were employed as effective adsorbents to remove matrix interferences in aquatic products, and their dosages were optimized. Satisfactory levels of accuracy and precision were procured under optimum conditions. The method limits of quantification ranged from 0.1 to 2.0 μg/kg. The analytical accuracy of the developed method for the analysis of multi-pesticide residues in freshwater and seafood products was validated. It was found to be suitable for the analysis of multi-pesticide residues in different types of aquatic products. Additionally, the method was successfully applied for the analysis of pesticide residues in fish samples obtained from aquaculture plants located in Zhejiang Province, China. The detected concentrations of pesticides ranged from 0.14 to 0.95 μg/kg. In general, this method shows promising application prospects for the rapid determination of multi-pesticide residues in aquatic products.

Progress on the development of a metal salt-assisted ionization source for the mass spectrometric analysis of polymers

The mass spectrometric analysis of polymers has been addressed as a challenging research topic due to poor ionization and complicated analysis using conventional mass spectrometry. The ionization source has demonstrated a promising future in rapid mass spectrometric analysis. Soft ionization techniques, such as electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) are the most ionization sources appeared to be a powerful tools for polymer characterization when combined with MS. However, they always need metal salts to be introduced during the ionization protocol for polymers due to the crucial role played by their ions (cations and anions). The current review focuses on the progress in the development of metal ion-assisted-ionization sources for the mass spectrometric analysis of polymers. Different ionization systems are comprehensively reviewed. The application of metal ion-assisted ESI, nanoESI, PSI, and MALDI-MS for polymer sample analyses is systematically discussed. The future research trends and challenges in this cutting-edge research field are summarized. It also aims to provide the current state-of-the-art of metal salts as a platform for ionization systems for the mass spectrometric characterization of polymers and offers the current challenges and perspectives on the promising future to improve analytical performance in this field. Finally, this mini-review provides a comprehensive handbook to researchers from different research backgrounds wishing to work in this area.

Polymers of micro(nano) plastic in household tap water of the Barcelona Metropolitan Area

Microplastics (MPLs) are emerging persistent pollutants affecting drinking water systems, and different studies have reported their presence in tap water. However, most of the work has a focus on particles in the 100-5 µm range. Here, a workflow to identify and quantify polymers of micro and nanoplastics (MNPLs), with sizes from 0.7 to 20 µm in tap water, is presented. The analytical method consisted of water fractionated filtration followed by toluene ultrasonic-assisted extraction and size-exclusion chromatography, using an advanced polymer chromatography column coupled to high-resolution mass spectrometry with atmospheric pressure photoionization source with negative and positive ionization conditions (HPLC(APC)-APPI(±)-HRMS) and normal phase chromatography HILIC LUNA® column and electrospray ionisation source in positive and negative mode (HPLC(HILIC)-ESI(±)-HRMS). The acquisition was performed in full scan mode, and the subsequent tentative identification of MNPLs polymers has been based on increasing the confirmation level, including the characterisation of monomers by using Kendrick Mass Defect (KMD) analysis, and confirmation and quantification using standards. This approach was applied to assess MNPLs in tap water samples of the Barcelona Metropolitan Area (BMA), that were collected from August to October 2020 from home taps of volunteers distributed in the 42 postal codes of the BMA. Polyethylene (PE), polypropylene (PP), polyisoprene (PI), polybutadiene (PBD), polystyrene (PS), polyamide (PA), and polydimethylsiloxanes (PDMS) were identified. PE, PP, and PA were the most highly detected polymers, and PI and PBD were found at the highest concentrations (9,143 and 1,897 ng/L, respectively). A principal component analysis (PCA) was conducted to assess differences in MNPLs occurrence in drinking water, that was provided from the two drinking water treatment plants (DWTPs) suppliers. Results showed that no significant differences (at 95% confidence level) were established between the drinking water supplies to the different areas of the BMA.

Polymer composition analysis of plastic debris ingested by loggerhead turtles (Caretta caretta) in Southern Tyrrhenian Sea through ATR-FTIR spectroscopy

The ingestion of anthropogenic plastic debris by marine wildlife is widespread in the Mediterranean Sea. The endangered status (in the IUCN Red List) of Loggerhead turtle (Caretta caretta, Linnaeus, 1758) is a consequence of its vulnerability. In this study, macro-/meso-plastics (5-170 mm) collected from faeces of twelve loggerhead turtles rescued (live) in the Aeolian Archipelago (Southern Tyrrhenian Sea, Italy) were analyzed by size, weight, shape, color and polymer type through Attenuated Total Reflectance Fourier-Transform Infrared Spectroscopy (ATR-FTIR). The defecation rate during hospitalization (7-14 days) varied among turtles (from 0.08 to 0.58). The mean number of plastic expulsions (2.7 ± 1.8 items for turtle) was higher during the 5th day of hospitalization (Kruskal-Wallis test, P = 0.01). However, the mean number of plastic-like items defecated during the common days of hospitalization did not vary among turtles (Kruskal-Wallis test, P > 0.05). All turtles were found to have ingested plastic. A total of 114 debris items were recovered from their faeces, 113 of which were identified as plastic. Their color was mostly white-transparent (64.9%) and light (19.3%). Shape was mainly fragments (52.6%), sheets (38.6%), followed by nylon, net-fragments, elastic plastic, foamed plastic and industrial granules (8.8%). Meso-plastics (5-25 mm) represented 72% of the total number of debris and were found more frequently in turtle with Curved Carapace Length (CCL) ≤ 60 cm (CCL = 30-60 cm, n = 5) than those with CCL >60 cm (CCL = 60-71 cm, n = 7). Plastic items were composed mainly of polyethylene (48.2%) and polypropylene (34.2%). Polypropylene (R² = 0.95, P < 0.001) and polyisoprene (R² = 0.45, P = 0.017) were more common in meso-plastics while polyethylene (R² = 0.44, P < 0.01) in macro-plastics. Finally, high-density polyethylene, polyvinyl chloride, polyamide and polyurethane were also found in some turtles. This study reveals high spreads of plastic contamination in faeces of both turtles with CCL ≤60 cm and CCL >60 cm, particularly vulnerable to the increasing quantity of floating plastic into their foraging sites highlighting the need of further research to associate debris ingestion with turtle diet and their size.

A novel polymeric fluorescence sensor based on acrylated citric acid for detection of melamine adulteration: Application in milk powder

Melamine selective acrylate citric acid (ACA) based polymeric membrane sensor was prepared by radical polymerization method and the sensor was characterized. The sensor showed a selective fluorescent response to melamine (λ_ex/λ_em = 388/425 nm). The sensor response is linear in the concentration range of 3.96 × 10^-9 to 7.93 × 10^-8 mol L^-1, the optimum pH value is 6.0 and response time is less than 1 min. Limit of detection (LOD) and limit of quantification (LOQ) were calculated as 2.32 × 10^-10 mol L^-1 and as 7.74 × 10^-10 mol L^-1, respectively. The sensor showed great selectivity towards melamine in the presence of a large number of molecules and ions. The performance of sensor was also confirmed by determining of melamine in milk powder sample and the results were compared with HPLC results and acceptable results were obtained. As a conclusion, the results revealed that the proposed sensor is an interesting alternative for melamine determination.

Development of a Solid-Phase Extraction Method Based on Biocompatible Starch Polyurethane Polymers for GC-MS Analysis of Polybrominated Diphenyl Ethers in Ambient Water Samples

A new solid-phase extraction (SPE) method for the extraction, enrichment, and analysis of eight polybrominated diphenyl ethers (PBDEs) in water was developed. The current approach involves using a cross-linked starch-based polymer as an extraction adsorbent and determining the PBDE analytes of interest using gas chromatography-mass spectrometry in negative chemical ionization mode (GC-NCI-MS). The starch-based polymer was synthesized by the reaction of soluble starch with 4,4'-methylene-bis-phenyldiisocyanate as a cross-linking agent in dry dimethylformamide. Various parameters impacting extraction efficiencies, such as adsorbent quantity, sample volumes, elution solvents and volumes, and methanol content, were carefully optimized. The 500 mg of starch-based polymer as an adsorbent used to extract 1000 mL of spiked water, presented high extraction recoveries of eight PBDEs. The linearity of the extraction process was investigated in the range of 1-200 ng L-1 for BDE-28, 47, 99, 100, and 5-200 ng L-1 for BDE-153, 154, 183, and 209, with coefficients of determination (r2) exceeding 0.990 for all PBDEs. The limits of detection (LODs) ranged from 0.06 to 1.42 ng L-1 (S/N = 3) and the relative standard deviation values (RSD) were between 3.6 and 9.5 percent (n = 5) under optimum conditions. The method was successfully used to analyze river and lake water samples, where it exhibited acceptable recovery values of 71.3 to 104.2%. Considering the excellent analytical performance and comparative cost advantage, we recommend the developed starch-based SPE method for routine extraction and analysis of PBDEs in water media.

Scaling Relationship in Chromatin as a Polymer

Genomic DNA, which controls genetic information, is stored in the cell nucleus in eukaryotes. Chromatin moves dynamically in the nucleus, and this movement is closely related to the function of chromatin. However, the driving force of chromatin movement, its control mechanism, and the functional significance of movement are unclear. In addition to biochemical and genetic approaches such as identification and analysis of regulators, approaches based on the physical properties of chromatin and cell nuclei are indispensable for this understanding. In particular, the idea of polymer physics is expected to be effective. This paper introduces our efforts to combine biological experiments on chromatin kinetics with theoretical analysis based on polymer physics.

Programmable Zwitterionic Droplets as Biomolecular Sorters and Model of Membraneless Organelles

Increasing evidence indicates that cells can regulate biochemical functions in time and space by generating membraneless compartments with well-defined mesoscopic properties. One important mechanism underlying this control is simple coacervation driven by associative disordered proteins that encode multivalent interactions. Inspired by these observations, programmable droplets based on simple coacervation of responsive synthetic polymers that mimic the "stickers-and-spacers" architecture of biological disordered proteins are developed. Zwitterionic polymers that undergo an enthalpy-driven liquid-liquid phase separation process and form liquid droplets that remarkably exclude most molecules are developed. Starting from this reference material, different functional groups in the zwitterionic polymer are progressively added to encode an increasing number of different intermolecular interactions. This strategy allowed the multiple emerging properties of the droplets to be controlled independently, such as stimulus-responsiveness, polarity, selective uptake of client molecules, fusion times, and miscibility. By exploiting this high programmability, a model of cellular compartmentalization is reproduced and droplets capable of confining different molecules in space without physical barriers are generated. Moreover, these biomolecular sorters are demonstrated to be able to localize, separate, and enable the detection of target molecules even within complex mixtures, opening attractive applications in bioseparation, and diagnostics.

DNA Conformation Dictates Strength and Flocculation in DNA-Microtubule Composites

Polymer topology has been shown to play a key role in tuning the dynamics of complex fluids and gels. At the same time, polymer composites, ubiquitous in everyday life, have been shown to exhibit emergent desirable mechanical properties not attainable in single-species systems. Yet, how topology impacts the dynamics and structure of polymer composites remains poorly understood. Here, we create composites of rigid rods (microtubules) polymerized within entangled solutions of flexible linear and ring polymers (DNA) of equal length. We couple optical tweezers microrheology with confocal microscopy and scaled particle theory to show that composites with linear DNA exhibit a strongly nonmonotonic dependence of elasticity and stiffness on microtubule concentration due to depletion-driven polymerization and flocculation of microtubules. In contrast, composites containing ring DNA show a much more modest monotonic increase in elastic strength with microtubule concentration, which we demonstrate arises from the decreased conformational size and increased miscibility of rings.

The separation characteristics and performance evaluation of the silica-based poly(pentabromostyrene) stationary phase in capillary electrochromatography

A mixed-mode capillary column packed with silica-based poly(pentabromostyrene) particles (denoted as SiO₂@pPBS) was prepared and applied to capillary electrochromatography (CEC) separation. With the presence of benzene rings and bromine atoms in polymer chains, the SiO₂@pPBS column provides a reversed-phase/hydrophilic mixed-mode retention mechanism owing to hydrophilic, hydrophobic and π-π interactions between the stationary phase and various analytes, including alkylbenzenes, polycyclic aromatic hydrocarbons, nucleosides, phenols and anilines. In CEC mode, the separation behavior of charged solutes is not only related to the interaction with the stationary phase, but also influenced by electrophoretic effects, which may lead to different selectivities compared to high performance liquid chromatography (HPLC). A column efficiency of up to 1.22 × 10⁵ N m^-1 was achieved for p-chloroaniline. Besides, the RSDs of retention time of anilines for run to run (n = 5), day to day (n = 5) and column to column (n = 3) were all less than 4.4%. Finally, the SiO₂@pPBS capillary column was applied to the separation of coking wastewater with satisfactory results. All the results demonstrated that the SiO₂@pPBS capillary packed column with RP/HILIC mixed-mode has great application potential.

Identification of Water-Soluble Polymers through Discrimination of Multiple Optical Signals from a Single Peptide Sensor

The pollution of water environments is a worldwide concern. Not only marine pollution by plastic litter, including microplastics, but also the spillage of water-soluble synthetic polymers in wastewater have recently gained increasing attention due to their potential risks to soil and water environments. However, conventional methods to identify polymers dissolved in water are laborious and time-consuming. Here, we propose a simple approach to identify synthetic polymers dissolved in water using a peptide-based molecular sensor with a fluorophore unit. Supervised machine learning of multiple fluorescence signals from the sensor, which specifically or nonspecifically interacted with the polymers, was applied for polymer classification as a proof of principle demonstration. Aqueous solutions containing different polymers or multiple polymer species with different mixture ratios were identified successfully. We found that fluorophore-introduced biomolecular sensors have great potential to provide discriminative information regarding water-soluble polymers. Our approach based on the discrimination of multiple optical signals of water-soluble polymers from peptide-based molecular sensors through machine learning will be applicable to next-generation sensing systems for polymers in wastewater or natural environments.

Preparation of a polydopamine/β-cyclodextrin coated open tubular capillary electrochromatography column and application for enantioseparation of five proton pump inhibitors

An open tubular capillary electrochromatography column was prepared by immobilizing β-cyclodextrin on the inner wall of pretreated capillary via noncovalent adsorption of polydopamine. The resulting coating layer on the capillary was characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. Electroosmotic flow was studied to evaluate the variation of the immobilized columns. The prepared columns showed good chiral separation performance toward five proton pump inhibitors including lansoprazole, pantoprazole, tenatoprazole, rabeprazole, and omeprazole. The influences of β-cyclodextrin concentration, coating time, buffer pH, buffer concentration, and applied voltage on separation were investigated. In the optimum conditions, the enantiomers of five analytes were fully resolved within 15 min with high resolutions of 4.57 to 8.13. The method was extensively validated in terms of accuracy, precision, and linearity and proved to be robust. The relative standard deviation values for migration times and peak areas of the analytes representing intraday and interday were less than 1.9 and 3.6%, respectively. Further, the polydopamine/β-cyclodextrin coated capillary column could be successively used over 100 runs without showing significant decrease in the separation efficiency.

Analytical implications of different methods for preparing plant cell wall material

Almost all plant cells are surrounded by a wall constructed of co-extensive networks of polysaccharides and proteoglycans. The capability to analyse cell wall components is essential for both understanding their complex biology and to fully exploit their numerous practical applications. Several biochemical and immunological techniques are used to analyse cell walls and in almost all cases the first step is the preparation of an alcohol insoluble residue (AIR). There is significant variation in the protocols used for AIR preparation, which can have a notable impact on the downstream extractability and detection of cell wall components. To explore these effects, we have formally compared ten AIR preparation methods and analysed polysaccharides subsequently extracted using high-performance anion exchange chromatography (HPAEC-PAD) and Micro Array Polymer Profiling (MAPP). Our results reveal the impact that AIR preparation has on downstream detection of cell wall components and the need for optimisation and consistency when preparing AIR.

Nontargeted Analysis of Face Masks: Comparison of Manual Curation to Automated GCxGC Processing Tools

Masks constructed of a variety of materials are in widespread use due to the COVID-19 pandemic, and people are exposed to chemicals inherent in the masks through inhalation. This work aims to survey commonly available mask materials to provide an overview of potential exposure. A total of 19 mask materials were analyzed using a nontargeted analysis two-dimensional gas chromatography (GCxGC)-mass spectrometric (MS) workflow. Traditionally, there has been a lack of GCxGC-MS automated high-throughput screening methods, resulting in trade-offs with throughput and thoroughness. This work addresses the gap by introducing new machine learning software tools for high-throughput screening (Floodlight) and subsequent pattern analysis (Searchlight). A recursive workflow for chemical prioritization suitable for both manual curation and machine learning is introduced as a means of controlling the level of effort and equalizing sample loading while retaining key chemical signatures. Manual curation and machine learning were comparable with the mask materials clustering into three groups. The majority of the chemical signatures could be characterized by chemical class in seven categories: organophosphorus, long chain amides, polyethylene terephthalate oligomers, n-alkanes, olefins, branched alkanes and long-chain organic acids, alcohols, and aldehydes. The olefin, branched alkane, and organophosphorus components were primary contributors to clustering, with the other chemical classes having a significant degree of heterogeneity within the three clusters. Machine learning provided a means of rapidly extracting the key signatures of interest in agreement with the more traditional time-consuming and tedious manual curation process. Some identified signatures associated with plastics and flame retardants are potential toxins, warranting future study to understand the mask exposure route and potential health effects.

Development of a new atmospheric pressure plasmaspray ionization for ambient mass spectrometry

A new atmospheric pressure ionization method, plasmaspray ionization, termed as PSI, was developed to be an alternative ambient ion source for mass spectrometry. It comprises a plasma jet device and a sample spray part. While the nonthermal plasma jet strikes the surface of stainless steel tube out of the spray capillary, the sprayed sample will be ionized with the assistant of auxiliary gas. Although PSI is a little bit more complex than electrospray ionization (ESI) in instrument, it shows both better linearity and higher sensitivity for organic compounds. For protein samples, it presents wider distributions of multiply charged ions and higher mass resolution without sacrificing any sensitivity. For the mechanism of PSI, the charge build-up process on the tip of capillary should play a key role for the ion formation, and the stimulated pulsed voltage on the flow tube will promote the ion aggregation speed until the charge density is high enough. PSI source contains the features of plasma ionization and ESI and can be considered as a novel combo bridging these techniques. These results reflect that this method of PSI can be applied and further developed as a versatile new ion source for a wild range of organic and biological samples.

Nanoscopic Structural Fluctuations of Disassembling Microtubules Revealed by Label-Free Super-Resolution Microscopy

Microtubules are cytoskeletal polymers of tubulin dimers assembled into protofilaments that constitute nanotubes undergoing periods of assembly and disassembly. Static electron micrographs suggest a structural transition of straight protofilaments into curved ones occurring at the tips of disassembling microtubules. However, these structural transitions have never been observed and the process of microtubule disassembly thus remains unclear. Here, label-free optical microscopy capable of selective imaging of the transient structural changes of protofilaments at the tip of a disassembling microtubule is introduced. Upon induced disassembly, the transition of ordered protofilaments into a disordered conformation is resolved at the tip of the microtubule. Imaging the unbinding of individual tubulin oligomers from the microtubule tip reveals transient pauses and relapses in the disassembly, concurrent with increased organization of protofilament segments at the microtubule tip. These findings show that microtubule disassembly is a discrete process and suggest a stochastic mechanism of switching from the disassembly to the assembly phase.

Recent advances and applications of molecularly imprinted polymers in solid-phase extraction for real sample analysis

Sample pretreatment is essential for the analysis of complicated real samples due to their complex matrices and low analyte concentrations. Among all sample pretreatment methods, solid-phase extraction is arguably the most frequently used one. However, the majority of available solid-phase extraction adsorbents suffer from limited selectivity. Molecularly imprinted polymers are a type of tailor-made artificial antibodies and receptors with specific recognition sites for target molecules. Using molecularly imprinted polymers instead of conventional adsorbents can greatly improve the selectivity of solid-phase extraction, and therefore molecularly imprinted polymer-based solid-phase extraction has been widely applied to separation, clean up and/or preconcentration of target analytes in various kinds of real samples. In this article, after a brief introduction, the recent developments and applications of molecularly imprinted polymer-based solid-phase extraction for determination of different analytes in complicated real samples during the 2015-2020 are reviewed systematically, including the solid-phase extraction modes, molecularly imprinted adsorbent types and their preparations, and the practical applications of solid-phase extraction to various real samples (environmental, food, biological, and pharmaceutical samples). Finally, the challenges and opportunities of using molecularly imprinted polymer-based solid-phase extraction for real sample analysis are discussed.

Side-chain fluorotelomer-based polymers in children car seats

Fabric and foam samples from popular children car seats marketed in the United States during 2018 were tested for fluorine content by particle-included gamma ray emission spectroscopy (PIGE, n = 93) and X-ray photoelectron spectroscopy (XPS, n = 36), as well as for per- and polyfluoroalkyl substances (PFAS) by liquid and gas chromatography mass spectrometry (LC/MS and GC/MS, n = 36). PFAS were detected in 97% of the car seat samples analyzed with MS, with total concentrations of 43 PFAS (∑PFAS) up to 268 ng/g. Fabric samples generally had greater ∑PFAS levels than foam and laminated composites of foam and fabric. The three fabric samples with the highest total fluorine content as represented by the highest PIGE signal were also subjected to ultraviolet (UV) irradiation and the total oxidizable precursor (TOP) assay. Results from these treatments, as well as the much higher organofluorine levels measured by PIGE compared to LC/MS and GC/MS, suggested the presence of side-chain fluorotelomer-based polymers (FTPs), which have the potential to readily degrade into perfluoroalkyl acids (PFAAs) under UV light. Furthermore, fluorotelomer (meth)acrylates were found to be indicators for the presence of (meth)acrylate-linked FTPs in consumer products, and thus confirmed that at least half of the tested car seats had FTP-treated fabrics. Finally, extraction of selected samples with synthetic sweat showed that ionic PFAS, particularly those with fluorinated carbons ≤8, can migrate from fabric to sweat, suggesting a potential dermal route of exposure.