Molecular Weight Distribution Research Articles

Dissimilar ferric derisomaltose formulations – In vitro comparisons between an originator and its intended similars

BackgroundThe complex nature of intravenous (IV) iron formulations makes manufacturing and characterising similars challenging. This study examined whether simple in vitro tests can distinguish the high-dose IV iron formulation, Monofer® (ferric derisomaltose [FDI]), from the first intended copies of FDI, Rapifer® (FDI intended similar A [FDIIS-A]) and Tosiron® (FDI intended similar B [FDIIS-B]), approved in India and Pakistan, respectively. Neither intended similar is available in Europe or the United States. MethodsIron content, pH, density, non-volatile residue, carbohydrate content, molecular weight distribution, complex robustness (measured using acid hydrolysis half-life [t½]) and free (dialysable) iron content were examined. Mean results from three batches of FDIIS-A were compared with mean values calculated from three batches of Monofer®. Due to product withdrawal, only one batch of FDIIS-B was available for comparison with Monofer®. ResultsIron content was similar for all formulations (∼100 mg/mL). The chromatograms (obtained using gel permeation chromatography) of FDIIS-A and FDIIS-B differed from that of Monofer®. FDIIS-A was substantially less robust than Monofer® (t½: 15 h versus 40.3 h); t½ for FDIIS-B was not tested. Free iron content was substantially higher in FDIIS-A (0.091 % w/v) and FDIIS-B (1.0 % w/v) versus Monofer® (<0.003 % w/v). Where tested, remaining parameters varied between the formulations (insufficient sample quantities prevented all tests being conducted for all intended similars). For all tests, greater inter-batch variability was seen for FDIIS-A versus Monofer®. ConclusionsSimple in vitro tests demonstrated that, aside from total iron content, the first intended similars of FDI bear little resemblance to their originator drug. It is clear that the efficacy and safety profile of Monofer® cannot be extrapolated to the two intended similars. The results call for increased regulatory scrutiny of intended IV iron similars.

Impact of the unimodal molar mass distribution on the mechanical behavior of polymer nanocomposites below the glass transition temperature: A generic, coarse-grained molecular dynamics study

Polymer nanocomposites (PNCs) have shown great potential to meet the ever-growing requirements of modern engineering applications. Nowadays, molecular dynamics (MD) simulations are increasingly employed to complement experimental work and thereby gain a deeper understanding of the complex structure–property relations of PNCs. However, with respect to the thermoplastic’s mechanical behavior, the role of its average molar mass M¯n is rarely addressed, and many MD studies only consider uniform (monodispersed) polymers. Therefore, this contribution investigates the impact that M¯n and the dispersity Đ have on the stiffness and strength of PNCs through coarse-grained MD. To this end, we employed a Kremer–Grest bead–spring model and observed the expected increase in the mechanical performance of the neat polymer for larger M¯n. Our results indicated that the unimodal molar mass distribution does not impact the mechanical behavior in the investigated dispersity range 1.0≤Đ≤1.09. For the PNC, we obtained the same M¯n-dependence and Đ-independence of the mechanical properties over a wide range of filler sizes and contents. This contribution proves that even simple MD models can reproduce the experimentally well researched effect of the molar mass. Hence, this work is an important step in understanding the complex structure–property relations of PNCs, which is essential to unlock their full potential.

Mesoscale modeling of random chain scission in polyethylene melts

Polyolefins account for more than half of global primary polymer production, however only a small fraction of these polymers are currently being recycled. Fragmentation of polymer chains into shorter chains with a targeted molecular weight distribution with the goal of reusing these fragments in subsequent chemical synthesis can potentially introduce an alternative approach to polyolefins recycling. Herein we develop a mesoscale framework to model degradation of polyethylene melts at a range of high temperatures. We use the dissipative particle dynamics approach with modified segmental repulsive potential to model the process of random scission in melts of linear polymer chains. We characterize the fragmentation process by tracking the time evolution of the distribution of degrees of polymerization of chain fragments. Specifically, we track the weight average and the number average degrees of polymerization and dispersity of polymer fragments as a function of the fraction of bonds broken. Furthermore, we track the number fraction distribution and the weight fraction distribution of polymer fragments with various degrees of polymerization as functions of the fraction of bonds broken for a range of high temperatures. Our results allow one to quantify to what extent the distribution of polymer chain fragments during random scission can be captured by the respective analytical distributions for the range of conversions considered. Understanding the thermal degradation of polyolefins on the mesoscale can result in the development of alternative strategies for recycling a range of thermoplastics.

Unlocking the potential of supramolecular polymers with bimodal molecular weights for instant and strong underwater adhesion

Developing adhesives suitable for underwater environments remains a formidable challenge due to the barrier presented by water, hindering contact between the adhesive and adherend. In this work, supramolecular adhesives prepared by mixing low and high molecular weight poly(butyl acrylate)-based copolymers are manifested to function effectively for underwater adhesion regardless of substrates’ affinity to water. Optimization of adhesion performance is achieved by manipulating the copolymer composition, resulting in the remarkable adhesion strengths of 1290 N/m and 1047 N/m to hydrophobic PET and hydrophilic glass substrates, respectively. The observed high underwater adhesion is attributed to a synergistic effect: instant and efficient removal of the hydration layer facilitated by the low molecular weight polymer strands, and mechanical resilience conferred by the high molecular weight strands featured by chain entanglements. Adequate interfacial interactions are attained by the supramolecular interactions including cation-π and π-π bonding. Notably, owing to its inherent hydrophobicity, the adhesive can be stored underwater for over a week and still displays 842 N/m peel strength to glass substrate. This work unlocks the potential of supramolecular adhesives with bimodal molecular weight distribution for instant and strong underwater adhesion, providing a straightforward yet scalable strategy to produce high-performance underwater adhesives.

Fractionation and refining of pectic oligosaccharides derived from onion skins through continuous feed diafiltration

In this work, a diafiltration-based process was investigated for the recovery of pectic oligosaccharides produced by subcritical water hydrolysis from onion skin waste. Four tubular ceramic membranes from 100 to 1 kDa were selected based on the molecular weight of the different galacturonic acid species present in the onion skin hydrolysate. All these membranes showed high selectivity towards pectic oligosaccharides, with low retention for free galacturonic acid, monosaccharides, organic acids, and other impurities. The 50 and 100 kDa membranes completely retained pectic oligosaccharides with a molecular weight exceeding 80 kDa, accounting for approximately 30 % of the initial pectic oligosaccharides in the hydrolysate. However, the purification rate was significantly slower using the 50 kDa membrane due to the increased cake layer resistance. Furthermore, it was examined a fractionation/purification cascade involving sequential diafiltration stages using 100, 10, and 1 kDa membranes at 25 °C, TMP = 1 bar, and a crossflow velocity of 1.5 m s−1. Approximately 87 % of the initial pectic oligosaccharides were successfully recovered and purified in the retentates, highlighting their potential for diverse applications due to their narrow molecular weight distribution, while phenolic compounds and other valuable low molecular weight molecules were recovered in the final permeate.

Controlled polymerization of functional acrylamides by rare-earth aryloxide-based Lewis pairs

A series of amine-bridged bis(phenolate) rare-earth (Sc, Y) aryloxides were synthesized and characterized. These complexes were successfully used for the controlled Lewis pair polymerization (LPP) of functional acrylamides in combination with phosphines, affording a new type of polyacrylamides with predictable molecular weight and low molecular weight distribution. The living nature of this LPP was verified by near-quantitative initiation efficiencies, a linear increase of molecular weight vs monomer-to-initiator ratio and monomer conversion, chain extensions, and the synthesis of well-defined block copolymers. The mechanistic studies were performed through the isolation of a zwitterionic intermediate as well as the end-chain analysis of oligomers, showcasing a rare-earth/phosphine cooperation. Furthermore, the resultant polyacrylamides exhibit outstanding thermal stability and great potential for application in photovoltaic devices.

Unlocking the potential of supramolecular polymers with bimodal molecular weights for instant and strong underwater adhesion

Developing adhesives suitable for underwater environments remains a formidable challenge due to the barrier presented by water, hindering contact between the adhesive and adherend. In this work, supramolecular adhesives prepared by mixing low and high molecular weight poly(butyl acrylate)-based copolymers are manifested to function effectively for underwater adhesion regardless of substrates’ affinity to water. Optimization of adhesion performance is achieved by manipulating the copolymer composition, resulting in the remarkable adhesion strengths of 1290 N m-1 and 1047 N m-1 to hydrophobic PET and hydrophilic glass substrates, respectively. The observed high underwater adhesion is attributed to a synergistic effect: instant and efficient removal of the hydration layer facilitated by the low molecular weight polymer strands, and mechanical resilience conferred by the high molecular weight strands featured by chain entanglements. Adequate interfacial interactions are attained by the supramolecular interactions including cation-π and π-π bonding. Notably, owing to its inherent hydrophobicity, the adhesive can be stored underwater for over a week and still displays 842 N m-1 peel strength to glass substrate. This work unlocks the potential of supramolecular adhesives with bimodal molecular weight distribution for instant and strong underwater adhesion, providing a straightforward yet scalable strategy to produce high-performance underwater adhesives.

Well-defined triphenylamine-containing polymers as hole-transporting layers in solution-processable organic light-emitting diodes via living anionic polymerization

In this study, we conducted anionic polymerization of N-[1,1′-biphenyl]-4-yl-N-(4′-ethenyl[1,1′-biphenyl]-4-yl)-9,9-dimethyl-9H-fluoren-2-amine (A) incorporating a triphenylamine group as a hole-transporting unit using sec-butyllithium and potassium naphthalenide as initiators in tetrahydrofuran at −30 ℃ for 10 min. The resultant poly(A)s exhibited controlled molecular weights (Mn = 20.9−126.3 kg/mol) and narrow molecular weight distributions (Mw/Mn ≤ 1.12). The living nature of the propagating chain end of poly(A) was confirmed by postpolymerization. Additionally, block copolymerization of A with styrene (St) and 2-vinylpyridine (2VP) was performed to assess its relative reactivity. Copolymerization resulted in the precise synthesis of well-defined block copolymers with poly(A) segments. Thermal properties of poly(A) were investigated using thermogravimetric analysis and differential scanning calorimetry. Notably, the thermal annealing of poly(A) film at 230 ℃ for 10 min made it insoluble in toluene, indicating its solvent resistance. Thus, poly(A) was used as the hole-transporting layer (HTL) in solution-processable organic light-emitting diodes (OLEDs). A comparative analysis against a reference device containing poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) revealed an enhancement in the performance of the OLED comprising thermally annealed poly(A) as the HTL. These results strongly suggest that poly(A) is a promising HTL material for solution-processable OLEDs.

Euglena gracilis Protein: Effects of Different Acidic and Alkaline Environments on Structural Characteristics and Functional Properties.

Due to the growing demand for human-edible protein sources, microalgae are recognized as an economically viable alternative source of proteins. The investigation into the structural characteristics and functional properties of microalgin is highly significant for its potential application in the food industry as an alternative source of protein. In this research, we extracted protein from Euglena gracilis by using alkaline extraction and acid precipitation and investigated its structural characteristics and functional properties in different acidic and alkaline environments. The molecular weight distribution of Euglena gracilis protein (EGP), as revealed by the size exclusion chromatography results, ranges from 152 to 5.7 kDa. EGP was found to be rich in hydrophobic amino acids and essential amino acids. Fourier infrared analysis revealed that EGP exhibited higher α-helix structure content and lower β-sheet structure content in alkaline environments compared with acidic ones. EGP exhibited higher foaming properties, emulsifying activity index, solubility, free sulfhydryl, and total sulfhydryl in pH environments far from its isoelectric point, and lower fluorescence intensity (2325 A.U.), lower surface hydrophobicity, larger average particle size (25.13 µm), higher emulsifying stability index, and water-holding capacity in pH environments near its isoelectric point. In addition, X-ray diffraction (XRD) patterns indicated that different acidic and alkaline environments lead to reductions in the crystal size and crystallinity of EGP. EGP exhibited high denaturation temperature (Td; 99.32 °C) and high enthalpy (ΔH; 146.33 J/g) at pH 11.0, as shown by the differential scanning calorimetry (DSC) results. The findings from our studies on EGP in different acidic and alkaline environments provide a data basis for its potential commercial utilization as a food ingredient in products such as emulsions, gels, and foams.

Genome-wide screening and characterization of phospholipase A (PLA)-like genes in sorghum (Sorghum bicolor L.).

The characterisation of PLA genes in the sorghum genome using in-silico methods revealed their essential roles in cellular processes, providing a foundation for further detailed studies. Sorghum bicolor (L.) Moench is the fifth most cultivated crop worldwide, and it is used in many ways, but it has always gained less popularity due to the yield, pest, and environmental constraints. Improving genetic background and developing better varieties is crucial for better sorghum production in semi-arid tropical regions. This study focuses on the phospholipase A (PLA) family within sorghum, comprehensively characterising PLA genes and their expression across different tissues. The investigation identified 32 PLA genes in the sorghum genome, offering insights into their chromosomal localization, molecular weight, isoelectric point, and subcellular distribution through bioinformatics tools. PLA-like family genes are classified into three groups, namely patatin-related phospholipase A (pPLA), phospholipase A1 (PLA1), and phospholipase A2 (PLA2). In-silico chromosome localization studies revealed that these genes are unevenly distributed in the sorghum genome. Cis-motif analysis revealed the presence of several developmental, tissue and hormone-specific elements in the promoter regions of the PLA genes. Expression studies in different tissues such as leaf, root, seedling, mature seed, immature seed, anther, and pollen showed differential expression patterns. Taken together, genome-wide analysis studies of PLA genes provide a better understanding and critical role of this gene family considering the metabolic processes involved in plant growth, defence and stress response.

Molecular Weight Distribution of Humic Acids Isolated from Calcic Cryosol in Central Yakutia, Russia.

The transition of soils into fallow state has a significant impact on the accumulation and transformation of soil organic matter (SOM). However, the issue of SOM transformation as a result of soil transition to fallow state in cryolithozone conditions is insufficiently studied. The aim of this study is to investigate the molecular weight (MW) distribution of humic acids (HAs) isolated from soils of central Yakutia. Native, fallow and agricultural soils in the vicinity of Yakutsk city were studied. MW distributions of HA preparations were obtained on an AKTAbasic 10 UPS chromatographic system (Amersam Biosciences, Uppsala, Sweden) using a SuperdexTM 200 10/300 GL column (with cross-linked dextran gel, fractionation range for globular proteins 10-600 kDa). The data on the molecular-mass distribution of HAs of fallow and agricultural soils of Central Yakutia were obtained for the first time. According to the obtained data, it was found that the highest carbon content in the structure of HAs was observed in agricultural soils (52.56%), and is associated with soil cultivation and fertilizer application. Among the HAs of fallow soils, we note that those soils that are in the process of self-vegetation have a relatively high carbon content in the HAs (45.84%), but the highest content was observed in fallow soils used as hayfields (49.98%), indicating that the reinvolvement of agriculture in fallow soils leads to an increase in the carbon content of HAs. According to the data of the MW distribution of HAs, it was found that the highest content of a high MW fraction of HAs was recorded in native soil (18.8%); this is due to the early stages of humification and the low maturity of organic matter. The highest content of a low MW fraction of HAs was recorded in agricultural soil (73.3%); this is due to the formation of molecular complexes of a "secondary" nature, which are more stable in the environment than the primary transformation products of humification precursors. The molecular composition of the HAs of fallow soils in the process of self-overgrowing is characterized by values closer to the HAs of native soils, which indicates their transformation towards HAs of native soils. The obtained results indicate that the reinvolvement of fallow soils leads to the transformation of the molecular composition of HAs towards HAs of agricultural soils, and to an increase in the resistance of SOM to biodegradation.

Leveraging Electron Push-Pull Effect for Catalytic Polymerization and Degradation of a Cyclobutane Monomer System.

Ring-opening polymerization (ROP) offers a striking solution to solve problems encountered in step-growth condensation polymerization, including precise control over molecular weight, molecular weight distribution, and topology. This has inspired our interest in ROP of cycloalkanes with an ultimate goal to rethink polyolefins, which clearly poses a number of challenges. Practicality of ROP of cycloalkanes is actually limited by their low polymerizability and elusive mechanisms which arise from significantly varied ring size and non-polar C-C bonds in monomers. In this work, by using Lewis acid/Brønsted base/C(sp3)-H initiator system previously developed in our laboratory, we focus on cyclobutanes and explore the positional and electronic effects of substituents on the ring, namely electron push-pull effect, in promoting controlled polymerization to afford densely functionalized poly(cyclobutanes), as well as catalytic degradation of obtained polymers for upcycling. More importantly, experiments and DFT calculations unveil considerable population of Lewis-acid-induced thermostabilized 1,4-zwitterions, which distinguish cyclobutanes from cyclopropanes and others. All these findings would shed light on catalytic synthesis and degradation of saturated all-carbon main-chain polymers, as well as small molecule transformations of cyclobutanes.

Leveraging Electron Push‐Pull Effect for Catalytic Polymerization and Degradation of a Cyclobutane Monomer System

AbstractRing‐opening polymerization (ROP) offers a striking solution to solve problems encountered in step‐growth condensation polymerization, including precise control over molecular weight, molecular weight distribution, and topology. This has inspired our interest in ROP of cycloalkanes with an ultimate goal to rethink polyolefins, which clearly poses a number of challenges. Practicality of ROP of cycloalkanes is actually limited by their low polymerizability and elusive mechanisms which arise from significantly varied ring size and non‐polar C−C bonds in monomers. In this work, by using Lewis acid/Brønsted base/C(sp3)‐H initiator system previously developed in our laboratory, we focus on cyclobutanes and explore the positional and electronic effects of substituents on the ring, namely electron push‐pull effect, in promoting controlled polymerization to afford densely functionalized poly(cyclobutanes), as well as catalytic degradation of obtained polymers for upcycling. More importantly, experiments and DFT calculations unveil considerable population of Lewis‐acid‐induced thermostabilized 1,4‐zwitterions, which distinguish cyclobutanes from cyclopropanes and others. All these findings would shed light on catalytic synthesis and degradation of saturated all‐carbon main‐chain polymers, as well as small molecule transformations of cyclobutanes.

Highly efficient dual photoredox/copper catalyzed atom transfer radical polymerization achieved through mechanism-driven photocatalyst design

Atom transfer radical polymerization (ATRP) with dual photoredox/copper catalysis combines the advantages of photo-ATRP and photoredox-mediated ATRP, utilizing visible light and ensuring broad monomer scope and solvent compatibility while minimizing side reactions. Despite its popularity, challenges include high photocatalyst (PC) loadings (10 to 1000 ppm), requiring additional purification and increasing costs. In this study, we discover a PC that functions at the sub-ppm level for ATRP through mechanism-driven PC design. Through studying polymerization mechanisms, we find that the efficient polymerizations are driven by PCs whose ground state oxidation potential—responsible for PC regeneration—play a more important role than their excited state reducing power, responsible for initiation. This is verified by screening PCs with varying redox potentials and triplet excited state generation capabilities. Based on these findings, we identify a highly efficient PC, 4DCDP-IPN, featuring moderate excited state reducing power and a maximized ground state oxidation potential. Employing this PC at 50 ppb, we synthesize poly(methyl methacrylate) with high conversion, narrow molecular weight distribution, and high chain-end fidelity. This system exhibits oxygen tolerance and supports large-scale reactions under ambient conditions. Our findings, driven by the systematic PC design, offer meaningful insights for controlled radical polymerizations and metallaphotoredox-mediated syntheses beyond ATRP.

Encapsulation of organic ultraviolet photoprotective actives into poly(methyl methacrylate) nanoparticles for sunscreen formulations

AbstractSkin cancer is the most common of all cancers worldwide. This way, it is mandatory to adopt an adequate sun protection routine, including sunscreen lotions. However, despite the proven effectiveness of numerous chemical filters, many of them are also known for their allergenic and carcinogenic potential effects, which can be mitigated by exploring some encapsulation routes. Thus, the present work evaluates the influence of seven distinct ultraviolet (UV) organic filters on the final particle size and molecular weight distributions of poly(methyl methacrylate) (PMMA) beads. Moreover, the sun protection factors (SPF) of the loaded nanoparticles are also evaluated when used for preparation of sunscreen formulations. The UV filters did not affect the course of MMA miniemulsion polymerizations significantly, enabling the synthesis of loaded nanoparticles. Nevertheless, adding the filters shifted the particle size distributions toward larger diameters, which are appropriate for cosmetic formulations. Based on the SPF analyses, it was also possible to observe a 12‐fold increase in the SPF values of the prepared formulations and an increase in the critical wavelength. Therefore, the in situ incorporation of distinct UV filters during miniemulsion MMA polymerizations constitutes a robust and versatile technology to produce PMMA nanoparticles loaded with UV filters for preparation of sunscreen formulations.

Understanding the Ecological Robustness and Adaptability of the Gut Microbiome in Plastic-Degrading Superworms (Zophobas atratus) in Response to Microplastics and Antibiotics.

Recent discoveries indicate that several insect larvae are capable of ingesting and biodegrading plastics rapidly and symbiotically, but the ecological adaptability of the larval gut microbiome to microplastics (MPs) remains unclear. Here, we described the gut microbiome assemblage and MP biodegradation of superworms (Zophobas atratus larvae) fed MPs of five major petroleum-based polymers (polyethylene, polypropylene, polystyrene, polyvinyl chloride, and polyethylene terephthalate) and antibiotics. The shift of molecular weight distribution, characteristic peaks of C═O, and metabolic intermediates of residual polymers in egested frass proved depolymerization and biodegradation of all MPs tested in the larval intestines, even under antibiotic suppression. Superworms showed a wide adaptation to the digestion of the five polymer MPs. Antibiotic suppression negatively influenced the survival rate and plastic depolymerization patterns. The larval gut microbiomes differed from those fed MPs and antibiotics, indicating that antibiotic supplementation substantially shaped the gut microbiome composition. The larval gut microbiomes fed MPs had higher network complexity and stability than those fed MPs and antibiotics, suggesting that the ecological robustness of the gut microbiomes ensured the functional adaptability of larvae to different MPs. In addition, Mantel's test indicated that the gut microbiome assemblage was obviously related to the polymer type, the plastic degradability, antibiotic stress, and larval survival rate. This finding provided novel insights into the self-adaptation of the gut microbiome of superworms in response to different MPs.

Variation of SARA fractions of crumb rubber modified asphalt binder-aggregate interface system and its correlation with adhesion properties

The incorporation of rubber powder leads to a high degree of complexity in the CRMA binder-aggregate interfacial properties, which directly affects the interfacial adhesion performance. The objective of this study is to investigate the variation of SARA fractions of CRMA binder during the adhesion process and to explore the intrinsic relationship between the components and the adhesion properties. To this end, the staged extraction tests were performed to extract CRMA binder layers on the aggregate surface. After each extraction, the binder layer was evaluated in terms of its SARA fraction contents and molecular weight distribution. Additionally, the pull-off tensile strength (POTS) was used to assess the adhesion of the binder-aggregate interface through the binder bond strength (BBS) test. Finally, the correlation between the SARA fractions of CRMA binder and interface adhesion of CRMA binder-aggregate system was analyzed. The results showed that the CR tends to absorb the lighter components of base asphalt, the variations in SARA fractions and molecular weight distribution during the aggregate adhesion to CRMA binders occurred mainly in the third and fourth elution layers. Pen 70 CRMA binder and limestone show the best adhesion properties among all the binder and aggregate types. The increase in CR size and the decrease in CR dosage are favorable for the adhesion of CRMA binders to aggregates. Furthermore, asphaltenes and resins are positively correlated with adhesion, while aromatics and saturants are negatively correlated with adhesion. The correlation between SARA content and adhesion varied depending on the aggregate type.

Comparison of protein digestibility of human milk and infant formula using the INFOGEST method under infant digestion conditions.

Many improvements have been made to bring infant formula (IF) closer to human milk (HM) regarding its nutritional and biological properties. Nevertheless, the protein components of HM and IF are still different, which may affect their digestibility. This study aimed to evaluate and compare the protein digestibility of HM and IF using the infant INFOGEST digestion method. Pooled HM and a commercial IF were subjected to the infant INFOGEST method, which simulates the physiological digestion conditions of infants, with multiple directions, i.e., the curd state, SDS-PAGE, molecular weight distribution, free amino acid concentration, and in vitro protein digestion rate. HM underwent proteolysis before digestion, and tended to have a higher protein digestion rate with finer curds during gastric digestion, than the IF. However, multifaceted analyses showed that the protein digestibility of HM and IF was not significantly different after gastrointestinal digestion. In conclusion, the infant INFOGEST method showed that the digestibility of HM and IF proteins differed to some extent before digestion and after gastric digestion, but not at the end of gastrointestinal digestion. The findings of this study will contribute to the refinement of IFs with better protein digestibility in infant stomach.

Co-Immobilization of Alcalase/Dispase for Production of Selenium-Enriched Peptide from Cardamine violifolia.

Enzymatically derived selenium-enriched peptides from Cardamine violifolia (CV) can serve as valuable selenium supplements. However, the industrial application of free enzyme is impeded by its limited stability and reusability. Herein, this study explores the application of co-immobilized enzymes (Alcalase and Dispase) on amino resin for hydrolyzing CV proteins to produce selenium-enriched peptides. The successful enzyme immobilization was confirmed through scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and Fourier-transform infrared spectroscopy (FTIR). Co-immobilized enzyme at a mass ratio of 5:1 (Alcalase/Dispase) exhibited the smallest pore size (7.065 nm) and highest activity (41 U/mg), resulting in a high degree of hydrolysis of CV protein (27.2%), which was obviously higher than the case of using free enzymes (20.7%) or immobilized Alcalase (25.8%). In addition, after a month of storage, the co-immobilized enzyme still retained a viability level of 41.93%, showing fairly good stability. Encouragingly, the selenium-enriched peptides from co-immobilized enzyme hydrolysis exhibited uniform distribution of selenium forms, complete amino acid fractions and homogeneous distribution of molecular weight, confirming the practicality of using co-immobilized enzymes for CV protein hydrolysis.

Sulfobetaine Zwitterions with Embedded Fluorocarbons: Synthesis and Interfacial Properties.

We describe the preparation of a new set of fluorinated sulfobetaine (FSB) zwitterionic polymers in which fluorocarbon moieties are attached directly to the zwitterionic components. An efficient two-step modification to the conventional sulfobetaine methacrylate monomer synthesis gave access to a series of polymer zwitterions containing varying extents of fluorocarbon character. FSB methacrylates proved amenable to homo- and copolymerizations using reversible addition-fragmentation chain transfer (RAFT) conditions, affording polymers with molecular weights ranging from 5 to 20 kDa and with low molecular weight distributions. Thin films of FSB homopolymers on glass proved stable to aqueous environments and exhibited increasing hydrophobicity with fluorocarbon content, as well as remarkably large water contact angle hysteresis values that enable pinning of water droplets on hydrophobic surfaces, reminiscent of the "petal effect" found in nature. FSB-containing copolymers in aqueous media demonstrated markedly reduced oil-water interfacial tension values, even with moderate (20-50 mol %) FSB incorporation.