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In continuation of previously reported results, the ionic liquid 1,5-diazabicyclo[4.3.0]non-5-ene-1-ium acetate was also found to be a powerful non-derivatizing solvent for cellulosic waste such as paper and cardboard. The ionic liquid could dissolve all the present bio-polymers (cellulose, hemicellulose, and lignin) in high concentrations, resulting in solutions with visco-elastic properties that were suitable for dry-jet wet fiber spinning. The cellulosic raw materials were refined gradually to identify the influence of residual components on the spinnability of the respective solution. Polymer degradation and losses in the spinning process could be avoided nearly entirely. With the exception of virtually unrefined cardboard, all the samples showed excellent spinnability, resulting in fibers with high tensile strength. Prototype textiles were produced to validate the quality of the fibers and demonstrate the possibility of using residual lignin in cardboard as a natural dye. [ABSTRACT FROM AUTHOR]

A lack of renewable resources and their inefficient use is a major challenge facing the society. Lignin is a natural biopolymer obtained mainly as a by-product from the pulp- and paper-making industries, and is primarily burned to produce energy. However, interest for using lignin in more advanced applications has increased rapidly. In particular, lignin based nanoparticles could find potential use in functional surface coatings, nanoglue, drug delivery, and microfluidic devices. In this work, a straightforward method to produce lignin nanoparticles from waste lignin obtained from kraft pulping is introduced. Spherical lignin nanoparticles were obtained by dissolving softwood kraft lignin in tetrahydrofuran (THF) and subsequently introducing water into the system through dialysis. No chemical modification of lignin was needed. Water acts as a non-solvent reducing lignin's degrees of freedom causing the segregation of hydrophobic regions to compartments within the forming nanoparticles. The final size of the nanoparticles depended on the pre-dialysis concentration of dissolved lignin. The stability of the nanoparticle dispersion as a function of time, salt concentration and pH was studied. In pure water and at room temperature the lignin nanoparticle dispersion was stable for over two months, but a very low pH or high salt concentration induced aggregation. It was further demonstrated that the surface charge of the particles could be reversed and stable cationic lignin nanoparticles were produced by adsorption of poly(diallyldimethylammonium chloride) (PDADMAC). [ABSTRACT FROM AUTHOR]

This paper reports the functionalization of heterogeneous hemicelluloses from Tacuara cane using the "click reaction". The synthesis was designed as a two-step strategy. The first step was the introduction of azido groups onto the backbone of hemicellulose by etherification of the natural polymer with 1-azido-2,3-epoxypropane to obtain HC-N3. In the second step, different terminal alkynes functionalized with aliphatic and aromatic groups were grafted onto HC-N3 by copper-catalyzed azide–alkyne cycloaddition (CuAAC). Hemicellulose-based products were obtained in high yields and further characterized using spectroscopic (NMR-1H and ATR-FTIR), thermal (TGA) and chromatographic techniques (HPAEC) evidencing that click chemistry is an attractive modification strategy to graft hemicellulose with different molecules through a triazole ring. This methodology was designed as a possible approach to valorise native hemicelluloses and to facilitate their use as a potential platform to support different reagents or biomolecules. [ABSTRACT FROM AUTHOR]

Biobased hydrogels have been widely used in drug delivery, tissue engineering and biosensors due to their abundance, non-toxicity and biocompatibility. However, constructing fully biobased hydrogels with good mechanical performance still remains a challenge. Herein, a double network (DN) hydrogel consisting of oxidized hydroxypropyl guar gum (OHPG) and gelatin (Gel) was fabricated via Schiff base reaction. The Gel-OHPG hydrogel had an elongation at break of 497%, a tensile stress of 0.44 MPa and a compressive stress of 25.91 MPa. Then, the mechanical properties of the hydrogel were further enhanced through immersing it in an ammonium sulfate (AMS) solution due to the Hofmeister effect. Its elongation could reach 629% and the corresponding tensile toughness and compressive stress were 3.86 MPa and 59.55 MPa, respectively. The conductivity of the hydrogel was 0.86 S m−1. Furthermore, the Gel-OHPG hydrogel was fabricated as a flexible sensor, and it could accurately monitor human joint motions such as fingers, wrists, knees, elbows, throat and neck. Henceforth, the Gel-OHPG hydrogel prepared using fully natural polymers has promising potential in flexible sensors and tissue engineering. [ABSTRACT FROM AUTHOR]

The utilization of resins combined with nanoparticles represents the prevailing method for fabricating superhydrophobic fabrics. Nevertheless, a notable drawback in this approach has been the limited durability of these fabrics, constraining their practical applications. In our ground-breaking study, we introduce an innovative and reliable solution to address this durability issue. We demonstrate, for the first time, that biopolymer resins offer a significantly enhanced level of durability to superhydrophobic fabrics when compared to their synthetic counterparts, whether organic or inorganic. Our proposed method employs the dip-coating technique, enabling us to create fabrics capable of maintaining their anti-wetting properties even in the face of mechanical stress. The deposition of this coating on the fabric surface elevates the water contact angle to an impressive 157°, with a sliding angle measuring below 10°. In terms of oils, the fabric surface exhibits superoleophilic behavior, with a contact angle of 0°. Furthermore, our coating exhibits outstanding thermal stability, enduring temperatures of up to 250 °C, while also demonstrating UV resistance for up to 50 hours without any loss of superhydrophobicity. Mechanical stability was also assessed, and the coating proved resilient against abrasion until the appearance of tears on the fabric, without compromising its superhydrophobic properties. Our coated fabric has been effectively employed in separating oil/water mixtures, achieving an exceptional separation efficiency of 99%, a performance that remains consistent across multiple cycles. We envision that these superhydrophobic/superoleophilic fabrics, characterized by their cost-effectiveness, eco-friendliness, remarkable durability, and ease of industrial scale application, hold immense potential for applications in clothing manufacturing and water/oil separation. [ABSTRACT FROM AUTHOR]

The paper reports on the development of a biopolymer chitosan based fluorophore for selective detection of Al3+ in aqueous streams. Fluorescence sensing based on the change in the photophysical properties of fluorophores is emerging as one of the favourite analytical techniques for environmental monitoring. We have developed a fluorophore by a simple and facile procedure involving two-step synthesis of (2-hydroxy napthalen-1-yl) azo chitosan (β-NAC) from the diazonium salt of the biopolymer chitosan and β-naphthol at low temperature. The resultant compound was characterized by UV-vis spectrophotometry, spectrofluorometry, FTIR, NMR, FESEM-EDX, PXRD and MALDI-TOF analysis. β-NAC shows characteristic absorption maxima at 327 nm in the UV region and fluorescence emission maxima at 427 nm with high intensity. The observed interaction of the β-NAC fluorescent compound was investigated as a fluorophore for several (alkali, alkaline and main group) metal ions and anions by monitoring the fluorescence response. The evident fluorescence quenching of β-NAC occurred in the presence of Al3+ metal ions up to the nanomolar range, confirming its high selectivity at low pH with a detection limit of 1.16 nM. The results of interference studies reinforce its selectivity in the presence of other metal ions and anions also. The distinct quenching parameters have been obtained by applying the Stern–Volmer plot at different temperatures and its analysis supported that the quenching mechanism is purely static in nature. The high KSV values show strong ground state complexation between β-NAC and Al3+ ion. From thermodynamic studies, ΔG values were found to be negative which confirms that the complexation process is spontaneous. [ABSTRACT FROM AUTHOR]

Chitosan is readily available from various biomass waste streams including crustaceans, cephalopods, insects, and fungus. The polymer possesses primary amine groups which are great handles for functionalization. Yet efficient functionalization with high degree of substitution is challenging to achieve via solvothermal methods due to limitations in chitosan solvation properties. Herein we report a mechanochemical and aging-based method directly addressing this point. Working in the solid phase helps stabilize the formation of Schiff bases from chitosan and aldehydes, affording a novel pathway to the green functionalization of chitosan by reductive alkylation, with unprecedentedly high degrees of substitution. The method showed great efficacy and compatibility for chitosan to be functionalized with 21 different aldehyde substrates and a low process mass intensity (PMI) of 36. This work also opens a new avenue for the development of mechanochemical and aging-based reductive amination transformations. [ABSTRACT FROM AUTHOR]

Natural vitamin E was extracted from crude palm oil and palm fatty acid distillate, both of which were converted into biodiesel before the extraction process. To enhance the stability of vitamin E, the study investigated the formation of inclusion complexes between vitamin E and β-cyclodextrin and hydroxypropyl-β-cyclodextrin. The results demonstrated improved thermal and light stabilities, prolonging the shelf life at room temperature while maintaining the antioxidant activity of vitamin E. Furthermore, the study successfully applied these complexes to poly(lactic acid) (PLA) fabrics, a biodegradable natural polymer, without altering their appearance. These findings underscore the potential of utilizing natural vitamin E from CPO and PFAD sources in the form of inclusion complexes for textile applications. [ABSTRACT FROM AUTHOR]

Photosynthetic microorganisms, such as cyanobacteria and microalgae, have great potential as living cell factories for chemical and fuel production. Immobilisation of cells is an effective technique for enhancing productivity and longevity of the production system, as well as aiding in the separation of cells from the medium. Alginate crosslinked with divalent ions is commonly used for immobilisation, however its ionic crosslinking is reversible in high ionic strength or in the presence of chelating agents leading to matrix degradation. To address these challenges, photocurable materials present a potential solution, especially when coupled with 3D-printing technologies to create complex, tunable 3D architectures for various applications. In this context, we propose a bioink composed of alginate, photocurable galactoglucomannan-methacrylate and photosynthetic cells for 3D-printing green biocatalysts for solar-chemical production. We demonstrate the applicability of this photocurable bioink for the immobilisation of photosynthetic microbes either capable of producing ethylene (specifically-engineered Synechocystis cell factories) or transforming cyclohexanone to e-caprolactone (specifically-engineered Chlamydomonas cell factories), both of which are industrially relevant chemicals. Films produced from photocurable bioinks demonstrate high mechanical stress tolerance compared to films prepared via conventional ionic crosslinking, showing resistance to high ionic strength in the medium. Furthermore, both Synechocystis and Chlamydomonas cells entrapped within 200 µm-thick hydrogel layers, 3D-printed on glass support surfaces, demonstrated notably high (ethylene) or similar (biotransformation of cyclohexanone to e-caprolactone) production titres and space-time yields compared to the conventional biocatalysts. These engineered living materials, being biocompatible and biobased, particularly when used in conjunction with 3Dprinting, provide convenient scalability and potential to enhance sustainability in the chemical industry. [ABSTRACT FROM AUTHOR]

Epiberberine is one of the main constituents of Coptidis Rhizoma and has been found to be active against diseases such as hyperglycemia, hyperlipidemia, and Alzheimer's disease. However, like other alkaloids its use is limited by rapid absorption, rapid metabolism and low transport to the brain. Nanotechnology has become a method of choice for a better delivery of active principles to the brain. The current study involved the use of a nanotechnological approach for the synthesis of epiberberine-loaded chitosan-collagen nanocomposites using natural polymers chitosan and collagen. This study was aimed at increasing the efficacy of epiberberine for dementia by decreasing the release rate and enhancing the anti-oxidant and AChE inhibition properties of epiberberine. The synthesized nanocomposites were found to be of small size (25 ± 2 nm) with more or less spherical morphology and showed slow release rate. Oxidative stress and impaired levels of acetylcholinesterase (AChE) are associated with the pathophysiology of Alzheimer's disease. These nanocomposites showed in vitro and in vivo anti-oxidant and AChE inhibition activity. Further, behavioral, biochemical, ELISA and immunohistochemical parameters were also used to evaluate the efficacy of these nanocomposites in a scopolamine-induced amnesia rat model. The results showed that these nanocomposites can reduce cognitive decline and are more effective against scopolamine-induced amnesia than epiberberine and the standard drug donepezil. At a similar concentration of 1 mg kg−1 body weight, the p-values of nanocomposites were smaller (approximately 10−4 to 10−2) in comparison to epiberberine and donepezil, indicating a significant effect against scopolamine-induced amnesia. [ABSTRACT FROM AUTHOR]

Casein/starch composites are shown to act as potential candidates for binders of symmetric carbonaceous electrodes used in the capacitive deionization (CDI) of water. Casein and potato-starch biopolymers are cheap and environmentally friendly and may be implemented throughout a green process to obtain a carbonaceous CDI electrode using sole water as a solvent. It was found that among the different starch/casein mass ratios considered in this study (0 : 1, 1 : 1, 2 : 1, 1 : 2, 1 : 4 and 1 : 0), the ratio 1 : 2 resulted in an optimal CDI performance corresponding to 12.7 mg g−1, 50% and 1.01 W h g−1 for salt adsorption capacity, charge efficiency, and specific energy consumption, respectively. The outstanding performance observed is attributed to the formation of a binder with a hydrophilic mesoporous network carrying inherent positive and negative charges throughout the internal surface area, inducing both anion and cation-exchange membrane characteristics in the binder layer. For the optimal binder composition, the latter network possesses a dominant pore diameter of 4.65 nm, while the dominant pore diameter is less than 3.00 nm for the other samples, eventually enhancing ion species mass transfer through the polymer matrix. [ABSTRACT FROM AUTHOR]

As global interest in carbon-neutrality policies grows, the demand for sustainable alternatives to fossil fuels intensifies. Herein, we demonstrate functionalized lignin-based n- and p-dopants for nanocarbon materials, providing promising eco-friendly alternatives to chemical dopants derived from fossil fuels. A simple microwave-assisted phenolation of organosolv lignin introduces phenol groups, offering additional reaction sites and enhancing solvent solubility for uniform, reliable and efficient carbon nanotube (CNT) doping. To create effective n- and p-dopants, the phenolated lignin is further functionalized with amine and hexafluoropropyl groups, respectively. The aminated and fluorinated lignin-doped CNTs present the Seebeck coefficients of −48.0 and 53.9 μV K−1, respectively, confirming an efficient and eco-friendly conversion between n- and p-type CNT. Notably, this n-doping performance is of particular significance since stable and reliable n-doping is challenging due to the inherent p-type semiconducting properties of CNTs. As a proof of concept, we demonstrate a flexible thermoelectric generator using 10 p–n pairs of the CNT films. The output voltage (7.86 mV) and output power (247 nW) of the flexible generator at ΔT = 15 K confirm that the aminated- and fluorinated lignin-doped CNT films exhibit n- and p-type characteristics, respectively. This study paves the way for sustainable, lignin-based doping of carbon nanomaterials, offering a green alternative to traditional fossil fuel-derived dopants and contributing to the transition towards carbon-neutral technologies. [ABSTRACT FROM AUTHOR]

Lignin is one of the most abundant biopolymers on Earth and is considered as the primary resource of aromatic compounds. Recently, lignin has attracted attention from scientists and industrialists due to its inherent potential arising from its unique structure, which leads to its possible use in many applications. Many efforts have been made to ameliorate the reactivity and compatibility of lignin in different areas. Although methods have been proposed for endowing lignin with different properties, there continues to be a considerable demand for discovering new and effective ways of unraveling the beneficial uses of this aromatic polymer. Considering the structure of lignin, different grafting modifications can occur on the aliphatic and/or aromatic groups of lignin. To date, there has been a lack of fundamental understanding of the modification pathways of lignin for generating lignin-based products. In this review paper, we discuss comprehensively the chemical reactions that were introduced in the literature for preparing lignin with different features via modifying its phenolic and aliphatic hydroxy groups for altered uses. This review paper critically and comprehensively elaborates on the recent progress in lignin reactions as well as the challenges, advantages and disadvantages associated with the reaction procedures and the product development processes. Furthermore, the research gap in reaction strategies and product development are described throughout this study. [ABSTRACT FROM AUTHOR]

The development of highly efficient and environmentally friendly solvents for dissolving cellulose, which is the most abundant natural polymer on Earth, remains a challenge, hindering its full utilization. Herein, a green protic ionic liquid, 1,1,3,3-tetramethylguanidinium methoxyacetate ([TMGH][MAA]), was found to exhibit attractive capacity to dissolve natural cellulose with an appropriate TMG/MAA molar ratio of 7 : 3 at 80 °C. The solubility of cotton linter and ultra-high molecular weight cotton fibers reached 13% (w/w) and 3% (w/w), respectively, surpassing that of most solvent systems currently used for the dissolution of cellulose. The experimental and simulation results verified that the excellent dissolution ability of [TMGH][MAA] for cellulose is mainly attributed to the destruction of the intrinsic hydrogen-bond networks in cellulose by the synergistic interactions of the [TMGH] cations and [MAA] anions with the hydroxyl groups in the cellulose chains, acting as highly efficient "intermolecular scissors". The superiority of this novel dissolution system was further demonstrated by the remarkable comprehensive properties of the regenerated cellulose film including satisfactory thermostability, high transparency, and excellent mechanical properties. Furthermore, the satisfactory recovery performance of this solvent highlights its significant feasibility for large-scale industrial manufacturing. The proposed [TMGH][MAA] in this study exhibits great potential as a next-generation processing solvent for dissolving, and thus processing cellulose, promoting the sustainable development of high-value-added cellulose materials. [ABSTRACT FROM AUTHOR]

Parahydrogen hyperpolarization has evolved into a versatile tool in NMR, allowing substantial sensitivity enhancements in analysis of biological samples. Herein we show how its application scope can be extended from small metabolites to underivatized oligopeptides in solution. Based on a homologous series of alanine oligomers, we report on an experimental and DFT study on the structure of the oligopeptide and hyperpolarization catalyst complexes formed in the process. We demonstrate that alanine oligomers coordinate to the iridium carbene-based catalyst in three different ways, each giving rise to distinctive hydride signals. Moreover, the exact structures of the transient oligopeptide-catalyst complexes are oligomer-specific. This work gives a first insight into how the organometallic iridium-N-heterocyclic carbene-based parahydrogen hyperpolarization catalyst interacts with biopolymers that have multiple catalyst binding sites. A preliminary application example is demonstrated for oligopeptide detection in urine, a complex biological mixture. [ABSTRACT FROM AUTHOR]

Degradable bone cement is widely used in the repair and treatment of bone defects due to its good plasticity and degradability and is also a good matrix for loading functional reagents or drugs. However, the release profile of drugs in bone cement will directly determine the performance of the bone cement. Coating drugs with natural polymer-based hydrogels is a common method of sustained drug release. Therefore, the magnesium gallate metal organic framework (Mg-MOF) with antibacterial properties is coated with oxidized dextran/gelatin (OD/Gel) and doped into the composite cement composed of calcium sulfate, calcium citrate and dicalcium phosphate anhydrous. The doping of OD/Gel@Mg-MOF has little effect on the microstructure and curing properties of the composite cement, but the mechanical strength of the cement increases from 27.20 MPa to 32.12 MPa. The controlled release of Mg-MOF can be sustainable for over 10 days, and OD/Gel@Mg-MOF bone cements exhibit excellent antibacterial properties against Staphylococcus aureus and Escherichia coli. Simultaneously, the composite bone cement can promote cell proliferation and osteogenic differentiation, alkaline phosphatase activity and calcium nodule deposition. [ABSTRACT FROM AUTHOR]

Catalytic depolymerisation of naturally occurring catechyl lignins (C-lignins) with benzodioxane linkages represents a direct and sustainable protocol for producing catechols, but the configuration of this process typically involves operation at high temperature, high H2 pressure, and high solvent-to-biomass ratios. Here, for the first time, we demonstrate that tris(pentafluorophenyl)borane (B(C6F5)3) can efficiently catalyse reductive cleavage of vicinal C–O bonds in benzodioxane structures with Et3SiH as a hydrogen donor. This homogeneous catalytic system can be generalized to C-lignin biopolymer derived from castor seed coats at room temperature and ambient pressure in highly concentrated form, thus giving silylated catechol derivatives in 85% yield. The as-depolymerized product is readily purified from the reaction mixture owing to high monomer selectivity. Reactivity screening of various C-lignin mimics, together with DFT calculations, offer an insight into the mechanistic understanding of the current depolymerisation of benzodioxane C-lignin. Overall, our results pave an economic and environmental pathway for producing catechols from biomass waste products. [ABSTRACT FROM AUTHOR]

The development of recyclable biopolymers from renewable resources is of great importance to sustainable development and environmental protection. Biopolymers not only provide a platform for achieving a friendly environment, but also reduce dependence on fossil fuel elements. In this study, a castor oil-based macromolecule prepolymer containing reactive isocyanate groups was firstly synthesized, and next a series of recyclable bio-polymers containing dynamic Diels--Alder bonds, imine bonds and hydrogen bonds were designed and fabricated by the introduction of furfural derivatives and vanillin. Dynamic covalent bonds and hydrogen bonds can bestow biopolymers with excellent comprehensive properties, including high self-healing efficiency, shape memory and reprocessability. Meanwhile, the formation of a reversible cross-linked network of hydrogen and dynamic bonds significantly improved the mechanical properties and endowed the biopolymers with self-healing capability. Fourier transform infrared spectroscopy and ¹H nuclear magnetic resonance indicate the successful preparation of the biopolymers. Thermal gravimetric analysis demonstrates that the materials as-prepared possess high thermal stability. Mechanical tests show that the materials have excellent mechanical properties with a maximum stress of 36.44 MPa. Surface scratches can be repaired at 120 °C for 5 minutes. The biopolymers also exhibit shape memory properties. This work will contribute to the development and study of functional self-healing biopolymers. [ABSTRACT FROM AUTHOR]

Chitosan (CS) is a natural polymer that exhibits many biological properties and is used as a biomaterial for antibacterial coatings, tissue engineering, cell research, drug delivery, and negatively charged molecule capture. In our previous study, we used a CS–polydopamine mixture to realize UV-assisted bonding between poly(methyl methacrylate) (PMMA) substrates to fabricate microdevices for self-assembled stem cell spheroid cultures. Herein, we attained reliable adhesive bonding between PMMAs using CS at room temperature assisted by oxygen plasma. The bond strength of adhesion was as high as 2.1 MPa, which could be stable for over two months according to the leak test. The adhesive bonding and surface functionalization of the microchannels were simultaneously completed such that the microdevices could be directly used for mesenchymal stem cell culture for spheroid generation and DNA purification for point-of-care testing (POCT) devices. Surface characterization was performed by contact angle measurements, Fourier-transform infrared spectroscopy, scanning electron microscopy, and atomic force microscopy. The POCT device allows sequential on-chip DNA purification, amplification, and colorimetric detection of pathogenic bacteria. This method provides a convenient and reliable strategy for the fabrication of PMMA microdevices that can be directly implemented in biological studies and POCT applications without involving prior surface modification steps. [ABSTRACT FROM AUTHOR]

In recent years, significant research has aimed at developing environmentally friendly supercapacitors by introducing biopolymeric materials, such as polysaccharides or proteins. In addition to the sustainability and recyclability of such novel energy storage devices, these polymers also provide flexibility, lightweight nature and stable cycling performance, which are of tremendous importance for applications related to wearable electronics. Among the different sustainable natural polymers, cellulose deserves special consideration since it is the most abundant and is extensively recycled. Consequently, research on electrically active cellulose-based supercapacitors has noticeably increased since 2012, which makes this review on the field timely. Specifically, recent advances in preparing high performance cellulose supercapacitors are summarized. Moreover, the key roles of cellulose in improving the specific capacitance and cycling stability of cellulose-based devices are compiled to offer important fundamental guidelines for designing the next generation of all-cellulose energy storage devices that are to come. Finally, challenges and perspectives in this exciting area of study are also discussed. [ABSTRACT FROM AUTHOR]

Cellulose is the most abundant renewable polymer resource in nature and cellulose-based materials are expected to serve as viable replacements to petroleum-based plastic products. However, the poor wet strength of cellulose limits its application as a high-strength material. Lignin is another abundant natural polymer in the biosphere. Inspired by the natural structure of wood fibers, researchers have added lignin to cellulose-based materials to effectively improve the wet strength while maintaining the environmentally friendly nature of these materials. This review comprehensively summarizes the current studies and describes the mechanisms underlying lignin-induced enhancement in the wet strength of wood fibers and cellulose-based materials. In addition, the influence of various methods for preparing cellulose-based materials is analyzed based on the introduction of ionic or chemical crosslinking or the thermal curing of lignin/cellulose-based materials to improve their wet strength. The use of environmentally friendly methods to improve the wet strength of cellulose-based materials is key in advancing the applications of these two abundant biomass resources. Finally, the future prospects of cellulose-based materials with lignin-enhanced wet strengths are discussed. This review contributes to the understanding of the physicochemical changes of lignin in cellulose-based materials and provides theoretical support for the wet strength of lignin-enhanced cellulose-based materials. [ABSTRACT FROM AUTHOR]

Hydrogen bonds (HBs) are vital construction fundamentals of natural biopolymers. Investigating the hydrogen bonding interactions of biopolymers is crucial for the conformation, transformation, and construction of their functional materials. In this study, a theoretical dissection of HBs in biopolymers such as cellulose, starch, chitin, and silk was conducted for determining their internal interactions, which are classified as neutral HBs, coordination bonds, and anionic/neutral HBs. The binding energies of HBs were decomposed into electrostatic interaction, exchange-repulsion force, induction interaction, and dispersion interaction. According to theoretical calculations, a green and low-cost zinc chloride/formic acid eutectic solvent was synthesized for dissolving biopolymers. These results indicated that this eutectic solvent has universal applications in the dissolution of various biopolymers and can be used to elucidate their HB interaction mechanism and binding energy changes. This study will provide a theoretical strategy for enhancing the room temperature dissolution of biopolymers and promoting green chemistry and the use of sustainable bioresources. [ABSTRACT FROM AUTHOR]

Human bones have unique structures and characteristics, and replacing a natural bone in the case of bone fracture or bone diseases is a very complicated problem. The main goal of this paper was to summarize the recent research on polymer materials as bone substitutes and for bone repair. Bone treatment methods, bone substitute materials as well as their advantages and drawbacks, and manufacturing methods were reviewed. Biopolymers are the most promising materials in the field of artificial bones and using biopolymers with the shape memory effect can improve the integration of an artificial bone into the human body by better mimicking the structure and properties of natural bones, decreasing the invasiveness of surgical procedures by producing deployable implants. It has been shown that the application of the rapid prototyping technology for artificial bones allows the customization of bone substitutes for a patient and the creation of artificial bones with a complex structure.

Membrane technology is a sustainable process of molecular separation and purification in the chemical and pharmaceutical industries, with lower energy consumption than traditional thermal methods. For sustainability reasons, the membrane fabrication itself needs to align with the 12 principles of green chemistry with low environmental impact, preferentially using natural polymers and green solvents. Membranes are currently mostly produced from petroleum-based polymers and organic solvents like dimethylformamide, which are not expected to be used in large amounts anymore. Lignin is a natural green polymer option, however its low solubility in mild solvents has limited its processability into membranes. We propose a sustainable membrane fabrication method using lignin fully dissolved in a green deep eutectic solvent (DES). The crosslinking with 5% epoxide in the aqueous medium enhanced the membrane stability, enabling its application in an aqueous and organic solvent medium. The resulting membrane had a molecular weight cut-off of 1.3 kg mol−1, a range relevant to molecular separation in the pharmaceutical and chemical industries. [ABSTRACT FROM AUTHOR]

Lithium sulfur (Li–S) batteries have become the predominant energy storage devices of the future. However, the reasons why Li–S batteries have not been widely commercialized include the shuttle effect of polysulfides and the volume expansion of sulfur active substances. In this study, a binder with a stretchable 3D reticular structure was induced using inorganic oligomers. Potassium tripolyphosphate (PTP) has been used to powerfully connect the tamarind seed gum (TSG) chain through robust intermolecular forces due to the strong electronegativity of P–O− groups. With this binder, the volume expansion of sulfur active substances can be well restrained. In addition, a large amount of –OH groups in TSG and P–O− bonds in PTP can also effectively adsorb polysulfides and inhibit the shuttle effect. Therefore, the S@TSG-PTP electrode shows an improved cycle performance. When the sulfur loading is as high as 4.29 mg cm−2, the areal specific capacity can reach 3.37 mA h cm−2 after 70 cycles. This study highlights a new way for the binder design of high-loading sulfur electrodes. [ABSTRACT FROM AUTHOR]

Keratin, a biological polymer with high sulfur content, is the main component of hair, feathers and wool. Human hair is the cheapest natural source of keratin. In this study, an optimized and very effective reduction reaction method was used to obtain keratin from human hair. During this process, the disulfide bridge of keratin was reduced in the presence of sodium sulfide to form free sulfhydryl (thiols) that would act as a strong nucleophile. The results of FTIR spectroscopy, Tricine-SDS-PAGE and MALDI-TOF/MS verified the successful extraction of the reduced human hair keratin. A well-interconnected structure with three-dimensional (3D) scaffolds was prepared using keratin and methacrylated gelatin (GelMA), KeratinGel, for tissue engineering and other biomedical applications. KeratinGel hydrogels were in situ prepared via Michael addition reaction and visible light crosslinking. Two complementary crosslinking reactions were combined to enhance the network structure and provide ductility. With the targeted two-step method, the reactivity of vinyl groups of GelMA to photocrosslinking and thiol groups in keratin to the Michael addition reaction was exploited. Rheological monitoring of the Michael addition reaction was performed for KeratinGel hydrogels in a basic reaction environment at pH 7.4 with a constant concentration of GelMA (10% w/v) and different amounts of reduced human hair keratin (5, 7.5 and 10% w/v) at room temperature. The physical properties, swelling and degradation rates of KeratinGel hydrogels were determined to understand their suitability for tissue regeneration. We finalize that KeratinGel hydrogels would be better in minimally invasive surgeries, soft tissue engineering, especially with in situ gelling features, and favourable for the preparation of complex shapes and applications. [ABSTRACT FROM AUTHOR]

In the transition towards the use of renewable resources, it is advantageous to be able to use biopolymers that are widely available with desirable functionalities. One of the most promising examples is chitosan. Chitosan can be derived from natural chitin which is cheaply available as a waste product from for example the food industry. However, one major limitation regarding chitosan's biological applicability is its limited solubility in plain water at neutral pH. Generally, to dissolve long-chain chitosan molecules, acidic conditions are required. The most common way to achieve this is by either the direct addition of organic or inorganic acids or via the addition of acidic chitosan salts. However, this severely limits its bioapplications as most biological processes are heavily pH dependent. Herein, we present a green and efficient solventless mechanochemical derivatization method, that involves the solid-state reaction between chitosan and 1,3-propane sultone, to make chitosan plain water soluble, meaning that the macromolecule completely dissolves at neutral pH without acidifying the solution in the process. To our knowledge, this is the most efficient chemical method for plain water-soluble chitosan compared to the current state-of-the-art, requiring a minimal amount of chemical input, as quantified by several green metrics. This could pave the way toward the valorization of waste into new bioactive materials via a sustainable process, taking major steps toward completely closing the loop. [ABSTRACT FROM AUTHOR]

Keratin is a biopolymer with high potential for biomaterial production, being principally investigated in hydrogel and film forms for use in tissue-engineering applications. Aiming to find sustainable solvents and develop an efficient keratin recovery process, this work used an aqueous solution of bio-based ionic liquid (IL) for the dissolution of chicken feathers. Complete dissolution of chicken feathers in an aqueous solution of cholinium acetate ([N111(2OH)][C1CO2]) was conducted at a solid : liquid weight ratio of 1 : 20 w/w, 100 °C for 4 h. An experimental design was carried out to optimize the keratin recovery conditions, investigating coagulant solvent, solution : coagulant weight ratio, and time. Under the optimal conditions (20.25 wt% of ethanol in water, 5 h, and solution : coagulant ratio of 1 : 1.45 w/w), 93 wt% of keratin was recovered. The IL was shown to be reusable in four successive cycles, with a yield of around 95 wt% and no significant losses in the efficiency of keratin recovery. These results demonstrate that an aqueous solution of [N111(2OH)][C1CO2] can lead to effective keratin recovery, serving as the basis for the development of a more effective and environmentally friendly process to recover biopolymers from waste. Due to the relevance of the developed process, techno-economic assessment through a comprehensive sensitivity analysis was carried out, evaluating a virtual operating biorefinery and showing a pathway that can enable the commercialization of produced keratin by the developed process. According to the process simulation, the minimum selling price for keratin is 22 $ per kg, with a small positive CO2 emission (4.04 kgCO2 kgkeratin−1), making this process suitable for biomedical and cosmetic applications. [ABSTRACT FROM AUTHOR]

Biopolymer nanoparticles have become highly important nanomaterials with great utility in the pharmaceutical and food fields. However, the excessive use of organic solvents in common fabrication approaches can cause potential risks to the environment and health. Herein, we report on the one-pot fabrication of pectin-based biopolymer nanoparticles through aqueous nanoprecipitation. An organic solvent-free citric acid solution (solvent)/water (or NaOH solution, non-solvent) shift can significantly switch the solubility of pectin by adjusting the citric acid content in the solution, triggering its supersaturation and subsequent phase separation from the water, allowing robust and scalable production of biopolymer nanoparticles with tunable sizes. The straightforward aqueous nanoprecipitation can be adapted to batch and continuous processes for the direct fabrication of pectin-based biopolymer nanoparticles. The nanoparticles show good colloidal stability in various aqueous environments. The particle size and solid content of the colloidal dispersion can be regulated by the feed concentration, target pH and solvent-shifting process. The versatility of this approach can lead to a high loading capacity (up to ∼52 wt%) of hydrophobic drugs or hydrophilic enzymes in the nanoparticles and on-demand engineering of multicomponent hybrid nanoparticles with tunable compositions, sizes and surface charges, showing great potential for the programmable fabrication of versatile biopolymer nanomaterials. [ABSTRACT FROM AUTHOR]

In this work, we describe the preparation and characterization of supramolecular ionic liquid gels based on binary mixtures of biopolymers, comprising chitosan, chitin, cellulose and lignin. The gels were obtained in ionic liquids differing in the cation or the anion, with no need for a cross-linking agent or acid treatment. The materials obtained were characterized for the minimum gelation concentration, porosity, swelling and rheological properties, finding a prominent influence of the nature of the ionic liquid anion. Then, we investigated the ability of the gels to scavenge free radicals, finding that the gels exhibit a higher antioxidant ability than their individual components. Moreover, our gels showed a bactericidal activity toward Gram-positive and Gram-negative bacterial strains like Streptomyces coelicolor and Escherichia coli, respectively. The kinetics of bacterial cell viability showed that the gel based on a chitosan : chitin mixture in the IL [bmim][Cl] was the fastest acting against E. coli, with a practically total killing of bacterial cells within 30 min. Once again, a major influence of the ionic liquid anion was detected. Finally, we found an inverse relationship between the antioxidant and antimicrobial activities of our gels. [ABSTRACT FROM AUTHOR]

Taking advantage of the facile dissolution of chitosan in the green [EMIM][OAc]/GVL-based organic electrolyte solution (OES) and the satisfactory ionic conductivity of the OES, a one-pot strategy for the preparation of a sustainable chitosan/nano-SiO2 nanocomposite organic ionogel electrolyte (CSOIE) was successfully demonstrated through the integration of in situ physical cross-linking via hydrogen bonding using nano-SiO2 and a solution-gel transition induced by moisture after the dissolution of chitosan in the OES. The [EMIM][OAc]/GVL OES not only acted as an efficient solvent for chitosan dissolution, but also ensured high ionic conductivity of the organic ionogel electrolyte and desired electrochemical performance in the assembled flexible supercapacitors over a wide working temperature range. It was found that the storage modulus of the chitosan/nano-SiO2 nanocomposite organic ionogel electrolyte (CSOIE) increased with an increase in the content of nano-SiO2, and the introduction of nano-SiO2 particles into the gel matrix enhanced the mechanical properties and ionic conductivity simultaneously. The as-prepared C8S2OIE sample exhibited high ionic conductivity over a wide temperature range (2.3, 24.3 and 60.3 mS cm−1 at −25, 25 and 80 °C, respectively), and a desirable compressive stress of 1.52 MPa at 25 °C. The assembled flexible supercapacitor using the C8S2OIE sample displayed excellent capacitive performance and temperature-dependent specific capacitance (72.8, 84.6 and 113.2 F g−1 at −25, 25 and 80 °C at 0.1 A g−1, respectively), and long-term stability after 10 000 charge–discharge cycles. It is believed that the satisfactory mechanical properties of the as-prepared CSOIE can be ascribed to both the physically cross-linked chitosan chains via hydrogen bonding and chain entanglement, as well as hydrogen bonding interactions between chitosan chains and nano-SiO2 particles; moreover, the physical interactions were beneficial for the formation of desirable ion channels, thus enabling outstanding electrochemical properties. Consequently, the findings provide significant insights for the design and preparation of sustainable organic ionogel electrolytes using natural polymers, and the outstanding performance of the as-prepared CSOIE suggests significant potential applications in flexible energy storage and conversion devices in the future. [ABSTRACT FROM AUTHOR]

Substitution of primary resources by solid waste and natural alternatives is being targeted worldwide. In this regard, this work aims to prepare a new environmentally friendly polymer nanocomposite based on a recycled polyester matrix and waste CaCO3. The novel aspect is filling the environmentally friendly polyester, obtained from natural biomass and natural oleic acid (BM-PES), with different concentrations of eggshell-waste-based calcium carbonate (ES-CaCO3) nanofiller, for the first time. ES-CaCO3, B 80 nm, was extracted by milling and calcination of solid eggshell waste, then added to the BM-PES matrix at concentrations of 3%, 5%, 7% and 10% to give the ES-CaCO3/BM-PES nanocomposites. The polymerized composites exhibited enhanced properties unlike those of the blank matrix. The microstructural investigations confirmed the successful preparation of the crystalline CaCO3 nanofiller. The obtained nanocomposites have improved thermal properties, owing to the increased thermal decomposition temperatures. The 7% and 10% ES-CaCO3/BM-PES nanocomposites achieved higher mechanical performance, where hardness and scratch resistance improved by 12.5% and 41.7%, respectively. The cone calorimetric parameters indicated the effective flame retardancy of the ESCaCO3 nanofiller, including the decreased peak heat release rate, specific extinction area, total smoke parameter and mass loss rate, as well the longer time to ignition, compared with the blank BM-PES matrix. The ES-CaCO3 nanofiller protects the natural BM-PES polymer from thermal deformation, mechanical failure and ignition. The characterization confirmed the thermo-mechanical and fireretardant properties of ES-CaCO3/BM-PES nanocomposites with the successful exploitation of eggshell solid waste and recycled polyester as an environmentally friendly feature. [ABSTRACT FROM AUTHOR]

Following global trends in launching plastic bans driven by the increasing problem of non-degradable plastic polluting the environment, cellulose as an abundant natural polymer has gradually been exploited as an eco-friendly material. Nevertheless, there are two challenging problems to overcome: it is hard to dissolve and heat seal (self-bonding under heat and pressing) cellulose, which hinder cellulose materials from replacing plastic. Here, a binder-free method is proposed to realize the bonding of cellulose film without any other binders. The heat-sealable cellulose film was fabricated with a low bonding temperature of 78 °C and high transparency of 90%. Furthermore, glycerol and sorbitol were introduced in the cellulose film not only to reduce the brittleness of the films but also to assist the confined-solvent-driven process. Possible mechanisms of self-bonding and for the tunable concentration range of the residual solvent, which was crucial for the self-bonding, are reported. Additionally, a sealed cellulose-based band and bags were successfully made, indicating the potential of our heat-sealable cellulose films to overcome the inherent limitations of cellulose and boost the potential use of cellulose films as candidates to replace plastic. [ABSTRACT FROM AUTHOR]

As the most abundant natural aromatic polymer on the Earth, lignin is expected to replace fossil resources for the preparation of high-performance thermosetting polymers. Numerous studies have been devoted to utilizing lignin through depolymerization and chemical modification; nevertheless, the green and facile valorization of lignin to high value products is still a challenge. Herein, we developed a straightforward approach to directly use lignin to prepare thermosetting polymers combining high performance and excellent degradability. In a green acetone–water–acetic acid component solvent system, lignin-based thermosets were facilely prepared via cross-linking reactions between lignin and glycidoxypropyltrimethoxysilane (KH560). The thermosets exhibited outstanding thermal and mechanical properties with a glass transition temperature of ∼214 °C, a tensile strength of ∼45 MPa and a Young's modulus of ∼2274 MPa, and these properties can be easily manipulated by adjusting the ratio of lignin to KH560. The presence of Si–O–C bonds and ester bonds in the network structure imparts excellent degradability to the thermosets in alkaline aqueous solution. This work provides a green and facile strategy to directly integrate lignin into cross-linked networks, which discloses a new idea for the valorization of lignin to value-added materials. [ABSTRACT FROM AUTHOR]

Natural biopolyesters in the form of suberin could be a promising resource for the synthesis of a wide array of chemicals, fuels and materials. However, access to this molecule is limited by a chemical-intensive and laborious work-up procedure based on alkaline hydrolysis or methanolysis. Herein, we propose the ultrafast supercritical hydrolysis as a novel and scalable approach for the facile access to suberin from cork. Supercritical water (SCW) with high or low ionic properties (pKw of 13 and 15) would allow the liquefaction of lignocellulosic materials while avoiding the hydrolysis of ester linkages. Therefore, extractives and carbohydrates partition in aqueous products while suberin and lignin are enriched in the solid products. Suberin yield reached as high as 66.6% of the dry cork at 386 °C and 1.27 s (pKw = 13), owing to the removal of up to 94.7% of polysaccharides content of the original cork biomass. The occurrence of repolymerization reaction, however, was observed under this condition, including an increase in Klason lignin presumably due to pseudo-lignin formation. Meanwhile, lower repolymerization products accompanied by a 77.1% polysaccharides and 14% lignin removal was achieved when working at 395 °C and 0.25 s (pKw = 15), at the expense of lower suberin yield of 59.8%. It appears that even a longer reaction time of 1.27 s would not lead to hydrolysis of ester linkages in suberin but influences the extent of liquefaction of the lignocellulosic matrix and the formation of repolymerization products. A lower ion product and a reaction time of less than 1 s would be preferable to strike a balance between maximum polysaccharides removal and minimum repolymerization products generation. This study has contributed towards the development of a new sustainable process to access valuable molecules from cork and has highlighted the importance of obtaining high quality and highly functionalized biopolymers as a source of new building blocks. [ABSTRACT FROM AUTHOR]

The selective activation of C–O ether bonds is an essential tool in organic synthesis and natural polymer depolymerization. However, the direct cleavage of the ether bond is still challenging work, especially breaking this inert and redox-neutral bond to provide one active carbon radical and another oxygen-centered fragment with oxidation capacity that can participate in the controllable radical reaction. We herein report that commercial 2H-MoS2 with negligible acidity can efficiently catalyze the benzylation of arenes with benzyl ethers, and a new Radical-Friedel–Crafts mechanism is proposed, which is quite different from the strong acid-catalyzed Friedel–Crafts mechanism. With dibenzyl ether as the model benzylation reagent, 2H-MoS2 can achieve the homolytic cleavage of the Bn–OR bond to generate the benzyl carbon radical and RO˙ species, identified by EPR measurement and radical trap experiments. The following radical-involved benzylation is confirmed by the Hammett results and a plausible pathway is proposed to clarify the Radical-Friedel–Crafts process. Heterogeneous 2H-MoS2 can be consecutively used four times without regeneration and it offers 94–95% yields of 2-benzyl-1,4-dimethylbenzene from dibenzyl ether and p-xylene in 30 min at 140 °C. Furthermore, this mechanism can provide some inspiration to activate the ether bond and to utilize ether as an oxidant in C–H bond activation. [ABSTRACT FROM AUTHOR]

A traditional method for preparing a gel electrode membrane is generally free radical polymerization or chemical cross-linking, which inevitably introduces toxic substances. In this work, an all-natural gel electrolyte membrane is prepared by condensing chitosan, sodium carboxymethyl cellulose, and tannic acid through a simple two-step method to achieve physical cross-linking through hydrogen bonding interactions. The hydrogel electrolyte membrane displays excellent mechanical properties with a strength of 2.8 MPa and an elongation of 35%, and a high ionic conductivity of 1.43 × 10−2 S cm−1; the flexible supercapacitor shows good electrochemical performance with a capacitance retention of 84% and an energy density of 14.29 Wh kg−1. Interestingly, based on the principle of sol–gel interaction, the electrochemical performance of the regenerated hydrogel electrolyte membrane remains stable, and the preparation method has also been proved to be a strategy universal to other natural polymer materials that contain the same functional groups. [ABSTRACT FROM AUTHOR]

For many years, the oil and gas industry has strived to develop environmentally friendly organophosphorus-based scale inhibitors. The natural polymer chitosan has recently gained significant importance for various upstream oil and gas applications. We earlier reported the synthesis of phosphonated chitosan (PCH) under conventional conditions in a two-step pathway via the Kabachnik–Fields reaction. This earlier work showed that PCH displayed good performance against calcite scaling and weak efficiency for barite scaling using a high-pressure dynamic tube-blocking rig at 80 bar and 100 °C using a produced water composition from the Heidrun oilfield, Norway. The mechanochemical synthesis approach has recently emerged as a powerful, green, and sustainable protocol in several industrial and academic applications. Herein, we report for the first time the synthesis of PCHvia the Moedritzer–Irani reaction using the ball-milling technique under liquid-assisted grinding conditions. The static inhibition performance of PCH is investigated, for the first time, against the gypsum scale and the calcite scale based on the NACE Standard TM0374-2007 protocol. The results are compared to the commercial polysaccharide, carboxymethyl inulin, (CMI), and aminotrismethylenephosphonic acid (ATMP) scale inhibitors. Furthermore, PCH was screened against the Heidrun calcite scale using static jar tests. The thermal stability and calcium compatibility properties of the mechanochemically synthesized PCH were investigated. The polymer exhibited an outstanding inhibition efficiency against both oilfield scales. It was also found that PCH showed excellent thermal stability after 7 days at 130 °C and excellent calcium compatibility properties at high calcium ion concentrations. Density functional theory (DFT) simulations were carried out to gain atomic insight into the interaction of PCH, CMI, and ATMP with the mineral surface. [ABSTRACT FROM AUTHOR]

Chemotaxis is a fundamental bacterial response mechanism to changes in chemical gradients of specific molecules known as chemoattractant or chemorepellent. The advancement of biological platforms for bacterial chemotaxis research is of significant interest for a wide range of biological and environmental studies. Many microfluidic devices have been developed for its study, but challenges still remain that can obscure analysis. For example, cell migration can be compromised by flow-induced shear stress, and bacterial motility can be impaired by nonspecific cell adhesion to microchannels. Also, devices can be complicated, expensive, and hard to assemble. We address these issues with a three-channel microfluidic platform integrated with natural biopolymer membranes that are assembled in situ. This provides several unique attributes. First, a static, steady and robust chemoattractant gradient was generated and maintained. Second, because the assembly incorporates assembly pillars, the assembled membrane arrays connecting nearby pillars can be created longer than the viewing window, enabling a wide 2D area for study. Third, the in situ assembled biopolymer membranes minimize pressure and/or chemiosmotic gradients that could induce flow and obscure chemotaxis study. Finally, nonspecific cell adhesion is avoided by priming the polydimethylsiloxane (PDMS) microchannel surfaces with Pluronic F-127. We demonstrated chemotactic migration of Escherichia coli as well as Pseudomonas aeruginosa under well-controlled easy-to-assemble glucose gradients. We characterized motility using the chemotaxis partition coefficient (CPC) and chemotaxis migration coefficient (CMC) and found our results consistent with other reports. Further, random walk trajectories of individual cells in simple bright field images were conveniently tracked and presented in rose plots. Velocities were calculated, again in agreement with previous literature. We believe the biopolymer membrane-integrated platform represents a facile and convenient system for robust quantitative assessment of cellular motility in response to various chemical cues. [ABSTRACT FROM AUTHOR]

Poly-2-hydrobutanedioic acid (P2HBD), produced by the yeast-like fungus Aureobasidium pullulans, is a new type of water-soluble polyhydroxy acid with potential applications in the biomaterial and biomedical fields. Generally, aerobic P2HBD fermentation with glucose as a carbon source causes carbon loss (releasing CO2) via the decarboxylation of pyruvate to form acetyl-CoA. Compared with sugars, the nonfermentable substrate ethanol exhibits a higher degree of reduction per carbon atom and a shorter route to generate acetyl-CoA. In this study, the carbon-economic biosynthesis of P2HBD driven by ethanol as the sole carbon source was investigated. Ethanol was first found to be efficiently converted into P2HBD via a biosynthetic mechanism, and specially activated the transcription factor Cat8 to regulate the glyoxylic acid shunt in A. pullulans. Based on transcriptomic analysis under ethanol stress, a modular assembly strategy was designed to balance three modules of ethanol oxidation, glyoxylic acid shunt, and the gluconeogenesis pathway, followed by precise regulation with promoter engineering. The congruent strain showed comparable yields with ethanol as the sole substrate. Moreover, an adaptive evolution strategy was performed to enhance ethanol tolerance. As a result, we obtained the mutant strain EGG 47, and resting cell fermentation achieved a comparable P2HBD titer and yield of 66.7 ± 0.77 g L−1 and 0.87 g g−1 ethanol in a 5 L fermenter, respectively. Our findings provide new insights into carbon-economic transformation from ethanol substrates into biopolymers and chemicals in third-generation biorefineries. [ABSTRACT FROM AUTHOR]

The use of model compounds in the development of selective lignin depolymerisation processes has been limited by the lack of complexity of these models compared with lignin itself. In this paper we report a convergent and efficient synthetic method for the flexible, multi-gram preparation of model lignin hexamers and octamers containing three of the most common connectivity motifs found within native lignin, namely β-O-4′, 5-5′ and β-5′, which will be used to further the mechanistic understanding of lignin depolymerisation processes. [ABSTRACT FROM AUTHOR]

The solubility parameter (SP) of a molecular species is a vital feature that indicates polarity and quantifies the 'like-seeks-like' principle, which is used in chemistry to screen solvents for dissolution. Recent studies have demonstrated that ionic liquids (ILs) and deep eutectic solvents (DESs) efficiently solubilize lignocellulosic biomass and promote enzymatic saccharification into sugars used for the production of biofuels and value-added chemicals. Understanding the solubility of plant biopolymers, particularly lignin, in ILs and DESs is critical for selecting candidate ILs and DESs for biomass pretreatment; however, experimentally measuring SPs is challenging. Thus, the present study investigates lignin dissolution mechanisms in IL/DES and prediction of the solubility parameters (Hildebrand and Hansen) of lignin, ILs, and DESs using multi-resolution simulation approaches. Solubility parameters of the studied compounds were predicted using molecular dynamics (MD) simulations, and the SP of lignin was determined to be 23–27 MPa1/2, which was close to the polymeric lignin solubility parameter (24.3–25.5 MPa1/2). The SPs of ILs namely [Ch][Lys], [Ch][Oct], and [Emim][Lys] were predicted to be ∼26 MPa1/2, which is close to lignin's SPs and resulted in increased biomass delignification. The MD simulated SPs were validated by both the COSMO-RS model and experimental investigations, with the results showing a close agreement between the predicted and experimentally obtained SPs. In addition, the enthalpy of vaporization (ΔHvap) of ILs/DESs was predicted based on the potential energy of the system, and the ΔHvap of ILs/DESs was around 40–65 kcal mol−1, which is 5–8 times higher than that of traditional organic solvents. [ABSTRACT FROM AUTHOR]

Near-infrared (NIR) fluorophores are emerging tools for biophotonics because of their reduced scattering, increased tissue penetration and low phototoxicity. However, the library of NIR fluorophores is still limited. Here, we report the NIR fluorescence of two benzene-fused oligo-BODIPYs in their hexameric (H) and octameric (O) forms. These dyes emit bright NIR fluorescence (H: maxima 943/1075 nm, O: maxima 976/1115 nm) that can be excited in the NIR (H = 921 nm, O = 956 nm) or non-resonantly over a broad range in the visible region. The emission bands of H show a bathochromic shift and peak sharpening with increasing dye concentration. Furthermore, the emission maxima of both H and O shift up to 20 nm in solvents of different polarity. These dyes can be used as NIR ink and imaged remotely on the macroscopic level with a stand-off distance of 20 cm. We furthermore demonstrate their versatility for biophotonics by coating microscale beads and performing microrheology via NIR video particle tracking (NIR-VPT) in biopolymer (F-actin) networks. No photodamaging of the actin filaments takes place, which is typically observed for visible fluorophores and highlights the advantages of these NIR dyes. [ABSTRACT FROM AUTHOR]

Given the high toxicity of inorganic inhibitors, organic substances, primarily heterocycles, have been proven to be one of the most efficient, cost-effective, and practical alternatives. Severe limitations in the application of organic corrosion inhibitors, particularly their environmental toxicity, have greatly accelerated the investigation of eco-friendly and sustainable alternatives. Corrosion control has made significant use of green chemistry ideas in recent years. This involves using different sustainable materials, techniques and strategies for corrosion control. Bio-based materials, including plant extracts, natural polymers, gums, waste, amino acids, and carbohydrates, are widely employed as sustainable materials. They are considered the best eco-friendly substitutes owing to their natural origin, biodegradability, and non-accumulation. Recently, several green synthetic techniques have been used to create green synthetic inhibitors, including microwave (MW) and ultrasonic (US) irradiation, particularly in conjunction with one-step multicomponent reactions (MCRs). Besides being green and sustainable, compounds derived from MW and US irradiation are more effective inhibitors than those obtained via traditional synthesis. Synthetic inhibitors derived using sustainable chemicals, solvents, and catalysts are also regarded as green alternatives. Inhibitors synthesized using natural substrates such as AAs and carbohydrates are semisynthetic alternatives. Recently, self-healing and synergism have emerged as additional environmentally friendly corrosion prevention methods. Computational modeling and simulations such as density functional theory (DFT), molecular dynamics (MD), and Monte Carlo (MC) simulations save money and resources by minimizing the number of experimental trials. Herein, we discuss the current research on using various eco-friendly and sustainable materials, technologies, and strategies for corrosion prevention together with their challenges and opportunities. [ABSTRACT FROM AUTHOR]

Despite indisputable advances in recent years, glioblastoma multiforme (GBM) remains one of the most lethal types of brain cancers. Hybrid matter-based nanostructures have exceptional potential as a multimodal tool against GBM by amalgamating the earliest possible diagnosis with options of therapy termed nanotheranostics. Thus, in this research, we report for the first time the rational design and synthesis of novel plasmonic–excitonic nanohybrids produced based on a green nanomedicine approach using a carboxymethylcellulose (CMC) multifunctional biopolymer acting simultaneously as a capping ligand and biocompatible shell through an eco-friendly aqueous colloidal process for nanotheranostics of brain cancer cells. These nanohybrids comprised of gold nanoparticles (AuNPs) coupled to a layer of ZnS semiconductor quantum emitter (ZnS-QE) surrounded by the CMC macromolecular shell (AuNP-ZnS@CMC), which displayed water-dispersed colloidal supramolecular nanoarchitectures stabilized by the polysaccharide chemical functional groups. They demonstrated nanotheranostic behavior by concurrently integrating the excitonic activity of the ZnS-QE layer for fluorescence bioimaging with the plasmonic properties of AuNPs for effectively killing GBM cancer cells in vitro. Hence, it can be anticipated that this hybrid nanoplatform could pave the way for the development of advanced multifunctional green nanomedicine against cancer through an environmentally sustainable strategy. [ABSTRACT FROM AUTHOR]

Biopolymer aerogels/foams exhibit wide applications, such as liquid separation and purification, gas separation, catalysis, and thermal insulation. However, their insufficient mechanical stability or complicated fabrication process often limits their practical application. In this work, we describe a facile and sustainable method to prepare robust foams; they are produced from the gelation of whey protein emulsions by manipulating intermolecular interactions. We demonstrate that hydrophobic interactions dominate the sol–gel transition by controlling protein aggregation and determine the linear viscoelasticity of the hydrogel. Blocking the hydrophobic interactions by adding guanidinium hydrochloride (GuHCl) led to a much lower degree of protein aggregation and promoted the formation of intermolecular disulfide bonds, enhancing protein adsorption on to oil droplets and imparting high elasticity to the hydrogel network. When the hydrogel was turned into a foam by freeze drying, the GuHCl foam exhibited outstanding mechanical properties (yield stress: 1.4 MPa; Young's modulus: 16.9 MPa), benefiting from the cellular structure and the synergistic effect of enhanced intermolecular disulfide bonds and oil droplets working as crosslinkers. Also, the foam possessed strong hydrophilicity and underwater oleophobicity (147.8° at pH 10 and 146.7° at pH 0), with resistance to oil fouling, and was successfully used as a filter medium to efficiently separate oil–water mixtures for repeated usage and to rapidly remove cationic dyes from their aqueous solutions. This study provides a universal strategy to design mechanically robust protein-based foams with multifunctionality. [ABSTRACT FROM AUTHOR]

In this paper we focus on the structural determination of biological orthogonal plywoods, fiber-like composite analogues of liquid crystalline phases, where the fibrils of the building blocks show sharp 90° orientation jumps between fibers in adjacent domains. We present an original geometric and computational modelling that allows us to determine the fibrillary orientation in biological plywoods from periodic herringbone patterns commonly observed in cross-sections. Although herringbone patterns were long reported, the specific and quantitative relationships between herringbones and the orthogonal plywoods were absent or at best incomplete. Here we provide an efficient and new procedure to perform an inverse problem that connects two specific features of the herringbone patterns (aperture angle and wavelength) with the 3D morphology of the structure, whose accuracy and validity were ascertained through in silico simulations and also with real specimens ("Eremosphaera viridis"). This contribution extends significantly the better known characterization methods of 2D cross sections, such as the arced patterns observed in biological helicoidal plywoods, and with the present proposed methodology it adds another characterization tool for a variety of biological fibrous composites that form cornea-like tissues.

Lactic acid bacteria (LAB) contamination during fuel ethanol fermentation can lead to significant economic loses. To circumvent this, fuel ethanol plants add antibiotics prophylactically, but their overuse has resulted in the emergence of antibiotic-resistant LAB strains. Lignin is a sustainable biopolymer that can be found as a waste product from lignocellulosic biorefineries. Technical lignins and their smaller phenolic subunits have been shown to exhibit broad-spectrum antimicrobial properties, but there is a lack of demonstrations of lignin derivatives with highly selective properties in the literature. Here, corn stover lignin from a biorefinery was oxidatively depolymerized using an environmentally benign organic oxidant, peracetic acid, into a bio-oil that has selective antimicrobial properties against LAB and not yeasts. The resulting bio-oil demonstrated up to 90% inhibition of commercially sampled LAB (including antibiotic-resistant strains) at 4 mg ml−1 with no inhibition against an industrial yeast strain. These antimicrobial properties of the bio-oil are attributed to larger unidentified lignin oligomers, compared to monolignols, that have a membrane damaging mode of action. Using the bio-oil (4 mg ml−1) during simultaneous saccharification and fermentation (SSF) of raw corn starch showed no inhibition of enzymatic activity, and in LAB contaminated fermentations the bio-oil treatments showed an 8% increase in ethanol yields at higher bacterial contamination ratios (l : 100 yeast to LAB, CFU per ml). This study illustrates the efficacy of using lignin bio-oil as an antibiotic replacement during fuel ethanol fermentation and demonstrates the highly selective antimicrobial properties of lignin oligomers, which creates a viable lignin valorization strategy for biorefineries. [ABSTRACT FROM AUTHOR]

Polymeric materials containing ionic liquid fragments, like those found in bulk ILs, are excellent solid media for the immobilisation of biocatalysts. Herein, the entrapment of the enzymatic system formed by alcohol dehydrogenase from Rhodococcus ruber (ADH-A) overexpressed in E. coli and its coenzyme has been studied. The activity, stability and reusability of these preparations have been investigated in the bioreduction of prochiral ketones finding excellent levels of conversion and selectivity. Interestingly, the immobilised enzyme remained active and exhibited excellent stability in aqueous solutions after several recycling uses. More importantly, these biopolymer materials retained most of their activity after consecutive reaction cycles, prolonged storage and under flow conditions. [ABSTRACT FROM AUTHOR]

Probably no other field of statistical physics at the borderline of soft matter and biological physics has caused such a flurry of papers as polymer translocation since the 1994 landmark paper by Bezrukov, Vodyanoy, and Parsegian and the study of Kasianowicz in 1996. Experiments, simulations, and theoretical approaches are still contributing novel insights to date, while no universal consensus on the statistical understanding of polymer translocation has been reached. We here collect the published results, in particular, the famous-infamous debate on the scaling exponents governing the translocation process. We put these results into perspective and discuss where the field is going. In particular, we argue that the phenomenon of polymer translocation is non-universal and highly sensitive to the exact specifications of the models and experiments used towards its analysis.