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Cross-linked melamine imprinted monoliths targeting glyphosate were synthesized using 4-phosphonobutanoic acid (PBA) and N-(phosphonomethyl)iminodiacetic acid (PMIDA) as templates. The binding capacities, evaluated in an aqueous medium, showed that both PMIDA and PBA promoted selective binding sites with imprinting factors of 2.5 and 1.7, respectively. Despite a relatively low imprinting factor, the polymer imprinted with PMIDA showed a noticeably higher binding efficiency in the presence of sodium chloride compared to the nonimprinted reference, demonstrating an ability to selectively target the desired analytes in real sample matrices. Spectroscopic investigations using Fourier transform infrared and 1H nuclear magnetic resonance spectroscopy revealed the formation of “memory pockets” for glyphosate molecules in the imprinted melamine-formaldehyde scaffold promoted by simultaneous contributions from (i) hydrogen bonding with N-H/O-H moieties and (ii) electrostatic interaction toward the triazine ring.

Methylmercury (MeHg) can form through the microbial transformation of divalent inorganic mercury (HgII). However, it remains unknown whether the total concentration of HgII is a main controlling factor for this methylation process in paddy soils unaffected by local Hg point sources. Here we study the occurrence and controlling factors for MeHg levels in non-contaminated rice paddy soil in Cambodia using 164 soil and 100 overlying water samples from different provinces in wet and dry seasons. Paddy soils were characterized with respect to particle size classes, nutrients, and biogeochemical parameters expected to influence Hg processes. Total mercury (THg) and MeHg concentrations in the soils were not related to geographical location or sampling season but to soil physical and chemical properties. We observed significant positive relationships between the concentrations of divalent inorganic Hg (HgII) and MeHg, suggesting that the concentration of HgII is the main factor determining the net formation of MeHg in non-contaminated rice paddy soils. The %MeHg of THg was used as a proxy of the potential for MeHg formation and was significantly, and inversely, correlated with the redox conditions of the soils, as approximated by the oxidation state of sulfur. The study elucidates critical factors driving MeHg levels in rice paddy soil, enhances the understanding of the MeHg formation process and provides a refined basis for soil quality regulation regarding Hg. The results suggest that reducing Hg inputs to paddies will be effective to lower MeHg concentrations in the soil, ultimately reducing its presence in rice grains.

Poly-(3-hydroxybutyrate), PHB, is a bacterial polyester in industrial demand as a biodegradable alternative to fossil-derived nondegradable plastics. Moreover, apart from being used directly as a bioplastic, valorization of PHB to its monomer building blocks and other value-added chemicals is feasible but less explored. In this study, Brønsted acid ionic liquid (BAIL) catalyzed depolymerization of PHB was investigated as a highly selective route to 3-hydroxybutyric acid, 3-HBA. The hydrolysis of PHB to 3-HBA was performed in a biphasic solvent medium composed of methyl isobutyl ketone (MIBK) and water, where the organic phase had dual roles as an efficient medium for dissolution of the polymer and as solvent for the monomeric products, which were enriched in this phase after cooling, with the Brønsted acid ionic liquid (BAIL) catalyst partitioned into the aqueous phase for facile recycling. The effects of reaction parameters, including the temperature, types of IL in terms of cations and anions, and the amount of water and IL, were studied to assess the yield of 3-HBA. Furthermore, protic acids such as sulfuric acid, methanesulfonic acid, and p-toluenesulfonic acid (p-TsOH) were also applied for comparison as acid catalysts for the hydrolysis of PHB to 3-HBA. Among the tested catalysts, the ILs containing the p-TsO- as anion as well as p-TsOH alone were found to be highly selective in promoting hydrolysis to 3-HBA, with complete depolymerization of PHB at >90% yield of 3-HBA in 4 h at 120 °C using a BAIL with sulfobutylated 1-methylimidazolium as the cation component and p-TsO- as the anion ([ImSO3H+][p-TsO-]). Although the use of p-TsOH as the sole catalyst also yielded efficient PHB hydrolysis with high reaction rates, it had a disturbing effect on the biphasic MIBK-water system by forming a single-phase reaction mixture at high 3-HBA yields, obstructing the recoveries of the products as well as the catalyst. In contrast, the biphasic reaction mixture remained intact when using IL as catalyst, which allowed facile and efficient separation of the product from the catalyst. Both the 3-HBA and the [ImSO3H+][p-TsO-] IL were recovered in high purity, the latter after applying a solvent extraction scheme based on ethyl acetate, whereby the recoveries of 3-HBA and IL reached ≈90%. The compositions of the synthesized ILs and the progress of the hydrolysis process, as well as the purity of the recovered product, were confirmed by NMR analysis. This sustainable approach to selective hydrolytic transformation of PHB into 3-HBA using a recoverable acidic IL catalyst in a biphasic solvent media of aqueous methyl isobutyl ketone hence resulted in efficient product separation and catalyst recovery.

To produce chitosan is an interesting research. Chitosan is an important polysaccharide in terms of its various applications in industries and is produced from chitin, an abundant biopolymer in crustacean shell biomass wastes. Traditional processes for chitosan manufacture are commonly based on highly concentrated alkaline or acid solutions which are, however, severely eroding and harmful to the environment. In this study, we have described a ‘greener’ method using 1-ethyl-3-methylimidazolium acetate, [Emim][OAc] ionic liquid (IL), for decrystallization of shrimp crystalline chitin flakes followed by a microwave-mediated NaOH or tetrabutylammonium hydroxide, [TBA][OH], solution-based deacetylation for chitosan production. The decrease in crystallinity in IL pre-treated chitin was confirmed by XRD and SEM analysis which subsequently benefited chitosan production with up to 85% degree of deacetylation (%DDA) in shorter time periods (1-2 hours) and lower alkaline concentrations (20-40%). The %DDA in chitin/chitosan was estimated via FT-IR and NMR analysis. Notably, we could regenerate the ionic liquids: in case of [Emim][OAc] 97 wt.% and in case of [TBA][OH] 83 wt.% could be reused. Roles of ionic liquids in the process were discussed. Molecular dynamics (MD) simulations showed the roles of [TBA]+ cations in the molecular driving forces of [TBA][OH]-induced deacetylation mechanism. The strategy promises a sustainable and milder reaction approach to the existing highly corrosive alkaline- or acid-involved processes for chitosan production.

N-Acetylneuraminic acid and its α2,3/α2,6-glycosidic linkages with galactose (Neu5Ac-Gal) are major carbohydrate antigen epitopes expressed in various pathological processes, such as cancer, influenza, and SARS-CoV-2. We here report a strategy for the synthesis and binding investigation of molecularly imprinted polymers (MIPs) toward α2,3 and α2,6 conformations of Neu5Ac-Gal antigens. Hydrophilic imprinted monoliths were synthesized from melamine monomer in the presence of four different templates, namely, N-acetylneuraminic acid (Neu5Ac), N-acetylneuraminic acid methyl ester (Neu5Ac-M), 3′-sialyllactose (3SL), and 6′-sialyllactose (6SL), in a tertiary solvent mixture at temperatures varying from −20 to +80 °C. The MIPs prepared at cryotemperatures showed a preferential affinity for the α2,6 linkage sequence of 6SL, with an imprinting factor of 2.21, whereas the α2,3 linkage sequence of 3SL resulted in nonspecific binding to the polymer scaffold. The preferable affinity for the α2,6 conformation of Neu5Ac-Gal was evident also when challenged by a mixture of other mono- and disaccharides in an aqueous test mixture. The use of saturation transfer difference nuclear magnetic resonance (STD-NMR) on suspensions of crushed monoliths allowed for directional interactions between the α2,3/α2,6 linkage sequences on their corresponding MIPs to be revealed. The Neu5Ac epitope, containing acetyl and polyalcohol moieties, was the major contributor to the sequence recognition for Neu5Ac(α2,6)Gal(β1,4)Glc, whereas contributions from the Gal and Glc segments were substantially lower.

The replacement of fossil-based plastics with biobased and biodegradable alternatives has become an important research challenge in recent years, aiming to eliminate the negative environmental impact of persistent plastics in nature. In this report, design of experiments was successfully exploited to develop an efficient and sustainable method for extracting intracellular PHA from Photobacterium ganghwense C2.2 using dihydrolevoglucosenone (Cyrene) and ethanol as biobased solvents obtainable from sustainable sources. The extraction conditions were studied and optimized against the yield and molecular weight. The temperature range for the extraction was scouted by using differential scanning calorimetry, while size exclusion chromatography coupled to refractive index and multiangle light scattering detectors was used to assess the molecular weights of the extracted polymers. The examined ranges in the model were, respectively, 1.6–8.4% (w/v) of lyophilized cells content per 10 mL of solvent, 3–17 min extraction time, and temperatures from 116 to 144 °C. Time and temperature strongly affected the extraction yields and molecular weights of the obtained polymers while the concentration of bacterial biomass only effected the molecular weight. Several quadratic and interaction coefficients were significant in the well-fit partial least-squares regression models (R² > 0.8, Q² > 0.6) indicating that nonlinear effects and interacting parameter contributed to the optimization targets. The optimized extraction should be performed at 130 °C for 15 min with 2% loading of bacterial biomass. The predicted yield and molecular weight of the polymer matched the values obtained from the real experiment under the optimized conditions. The method setup provided similar yield and higher molecular weight in much shorter time compared to overnight Soxhlet extraction with CHCl₃. The clean ¹H nuclear magnetic resonance spectra of polymers extracted from bacteria indicate that high purity materials can be obtained using an optimized extraction scheme. Additionally, the Cyrene solvent could be recycled at least five times and still performed the extraction equally well as the fresh solvent. Finally, the current method demonstrated a high potential for scalability using a HP4750 stirred filtration cell. Three different filtration conditions were tested, achieving up to 97.4% recovery at 80 °C using a 0.3 μm glass fiber membrane, with a flux of 312.5 LMH.

The novel process reported here described the manufacture of monolithic molecularly imprinted polymers (MIPs) using a terminally functionalized block copolymer as the imprinting template and pore-forming agent. The MIPs were prepared through a step-growth polymerization process using a melamine-formaldehyde precondensate in a biphasic solvent system. Despite having a relatively low imprinting factor, the use of MIP monolith in liquid chromatography demonstrated the ability to selectively target desired analytes. An MIP capillary column was able to separate monophosphorylated peptides from a tryptic digest of bovine serum albumin. Multivariate data analysis and modeling of the phosphorylated and nonphosphorylated peptide retention times revealed that the number of phosphorylations was the strongest retention contributor for peptide retention on the monolithic MIP capillary column.

In this report, 1-ethyl-3-methylimidazolium acetate, [EMIM][AcO] ionic liquid (IL) and acetic acid (AA) comprised solvents were used for the thermal treatment of poly (vinylidene difluoride), PVDF. Here, besides the various combinations of IL and AA in solvents, the pure IL and AA were also applied as a solvent upon thermal treatments. The samples obtained after the treatment were analysed for structural and crystalline phase changes, porosity, and molecular weight distribution with various analytical techniques. The Kamlet-Taft parameters measurement of the IL and AA containing solvents with different solvatochromic dyes was also performed to examine their solvent properties and correlate with the properties of the treated PVDF materials. The treatment of PVDF with pure IL results in the formation of highly carbonaceous material due to extensive dehydroflurination (DHF) as well as possibly successive cross-linking in the polymer chains. Upon IL and AA combined solvent treatment, the neat PVDF which composed of both α- and β crystalline phases was transformed to porous and β-phase rich material whereas in case of pure AA the non-porous and pure α-phase polymeric entity was obtained. A combined mixture of IL and AA resulted in a limited the DHF process and subsequent cross-linking in the polymer chains of PVDF allowed the formation of a porous material. It was observed that the porosity of the thermally treated materials was steadily decreasing with increase in the amount of AA in solvents composition and solvent with an AA:IL mole ratio of 2:1 resulted in a PVDF material with the highest porosity amongst the applied solvents. A recovery method for the IL and AA combined solvent after the thermal treatment of PVDF was also established. Hence, with varying the type of solvents in terms of composition, the highly carbonaceous materials as well as materials with different porosities as well as crystalline phases can be obtained. Most importantly here, we introduced new IL and AA containing recoverable solvents for the synthesis of porous PVDF material with the electroactive β-phase.

Polyhydroxyalkanoates (PHA) are promising biodegradable and biocompatible bioplastics, and extensive knowledge of the employed bacterial strain’s metabolic capabilities is necessary in choosing economically feasible production conditions. This study aimed to create an in-depth view of the utilization of Photobacterium ganghwense C2.2 for PHA production by linking a wide array of characterization methods: metabolic pathway annotation from the strain’s complete genome, high-throughput phenotypic tests, and biomass analyses through plate-based assays and flask and bioreactor cultivations. We confirmed, in PHA production conditions, urea catabolization, fatty acid degradation and synthesis, and high pH variation and osmotic stress tolerance. With urea as a nitrogen source, pure and rapeseed-biodiesel crude glycerol were analyzed comparatively as carbon sources for fermentation at 20 °C. Flask cultivations yielded 2.2 g/L and 2 g/L PHA at 120 h, respectively, with molecular weights of 428,629 g/mol and 81,515 g/mol. Bioreactor batch cultivation doubled biomass accumulation (10 g/L and 13.2 g/L) in 48 h, with a PHA productivity of 0.133 g/(L·h) and 0.05 g/(L·h). Thus, phenotypic and genomic analyses determined the successful use of Photobacterium ganghwense C2.2 for PHA production using urea and crude glycerol and 20 g/L NaCl, without pH adjustment, providing the basis for a viable fermentation process.

Valorization of renewable and biodegradable biopolymers to value added chemicals and green fuels is currently considered as an important research topic aiming at reducing the dependency on fossil derived feedstocks as well as their negative consequences on the environment. In this report, we are introducing an ionic liquid (IL) mediated, sustainable, and green synthesis of crotonic acid (CA) from poly-(3-hydroxybutyrate, PHB), a biopolymer derived from microbial fermentation. In this actual case, imidazolium cation comprising ILs have been used in the synthesis, where the influence of various reaction parameters such as reaction temperature and types of ILs as well as the amount of polymer, water, and IL in the reaction mixture were examined. The conversion of PHB to CA in IL took place by a base catalyzed depolymerization with formation of crotonyl terminated polymeric entities as intermediates, a mechanism that was confirmed by NMR analysis of the reaction mixtures sampled when the reactions were carried out at various temperatures. The rate of CA formation via the IL mediated base catalyzed depolymerization increased with increasing temperature in the tested interval, and 97% yield of CA was obtained after 90 min at 140 °C. The [EMIM][AcO] IL applied as solvent and catalyst is capable of completely depolymerizing PHB to CA in 5 h at 120 °C up to a polymer loading of 40 wt%. At higher loadings the depolymerization became incomplete, which is attributed to a deactivation of the IL due to hydrogen bonding interactions with the in situ formed CA, confirmed by NMR and DSC techniques. Since the depolymerization is base catalyzed, the only tested ILs that were able to form CA were based on acetate anions, whereas the less basic or neutral [EMIM][Cl] IL was found to be inactive. Finally, more than 90% of CA as well as [EMIM][AcO] IL were recovered in high purity by solvent extraction with brine (saturated aqueous NaCl) and 2-methyl tetrahydrofuran (2-Me-THF). Most importantly, here we introduce a sustainable, metal free, and single solvent based reaction approach for selective depolymerization of PHB to industrially valuable CA in basic and recoverable ILs.