Monomer Concentration Research Articles

Synthesis of amine-bridged bis(phenolate) rare-earth metal alkoxides and their catalytic performance for the polymerization of trimethylene carbonate and L‑lactide

A series of rare-earth metal complexes stabilized by amine-bridged bis(phenolate) ligand were synthesized and employed as initiators for the polymerization of trimethylene carbonate (TMC) and L‑lactide (L-LA). One-pot reaction of the amine-bridged bis(phenol) LH2 (L = (CH3)2NCH2CH2N[CH2-(2-OH-3-tBu-5-OMe-C6H2)]2) with (C5H5)3RE(THF) or Nd[N(SiMe3)2]3 in a 1:1 molar ratio, followed by the treatment of 1 equiv. of ROH (R = (CF3)2CH, CF3CH2) gave the amine bridged bis(phenolate) rare-earth metal alkoxides LRE(OCH(CF3)2)(THF)n (RE = La (1), n = 2; RE = Nd (2), Y (3), Yb (4), Lu (5), n = 1) and LNd(OCH2CF3)(THF)2 (6) in good isolated yields. These complexes were efficient initiators for the homopolymerization of both TMC and L-LA. Kinetics of the polymerization of TMC and L-LA initiated by complex 6 was investigated, and the results showed that the polymerizations of L-LA and TMC were first order for the initiator and monomer concentrations.

Monomer Transport in Emulsion Polymerization IV Gaseous Monomers

AbstractMethods for the evaluation of the Damkohler number for monomer transport during emulsion homopolymerization and copolymerization are extended to the analysis of gaseous monomers. Results indicate that the monomer transport limitation of gaseous monomers in both homo and copolymerization is strongly dependent on overall pressure through Henry's law relationship governing the concentration of monomer in the aqueous phase in equilibrium with monomer bubbles. At low pressures, most monomers studied exhibit monomer transport limitations; however, even at very high pressures, some gaseous monomers still exhibit monomer transport limitations.

BIOCOMPATIBLE P(TM co SA-CAA) HYDROGELS WITH pH RESPONSIVE AND ENHANCED MECHANICAL PERFORMANCE

In recent years, development of hydrogel that combines biocompatibility, pH responsive and mechanical performance has attracted the attention of researchers. A novel biocompatible hydrogel, composed of P(TM co SA) and P(TM co CAA) was synthesized by a simple admixture and heating process. The results show that with increasing levels of SA-CAA monomer concentration, an increase in tensile strength and elongation at breakpoint was observed and optimal at the ratios P(TM co SA CAA). Tensile strenght and young’s modulus registered an impressive increase of 43% and 40% respectively. These improvements are attributed to strong synergistic hydrogen bonding interactions between the TM and SA-CAA chains. During the experiment, maximum increase in weight was also achieved at pH 10 NaOH solution, it is show the pH-responsive hydrogels. The investigation of P(TM co SA-CAA) hydrogel mechanism showed that more homogenous dispersed through crosslinks dominated by β-sheets from Amide I structures. Furthermore, the SA-CAA molecules contributed to the biocompatibility, pH responsive and mechanical performance of P(TM co SA-CAA) hydrogels. Conclusively, its P(TM co SA-CAA) hydrogels clearly demonstrated the relevance of the provide a bioresponsive material for biomedical applications, such as tissue engineering, regenerative medicine and pH-sensitive drug delivery.

Hydroxyethyl Cellulose-Based Hydrogels as Controlled Release Carriers for Amorphous Solid Dispersion of Bioactive Components of Radix Paeonia Alba.

Radix Paeoniae Alba (RPA) has been used extensively in Chinese traditional medicine to treat gastrointestinal disorders, immune-modulating diseases, cancers, and numerous other conditions. A few of its active components include paeoniflorin, albiflorin, lactiflorin, and catechin. However, their therapeutic effectiveness is compromised by poor pharmacokinetic profiles, low oral bioavailability, short half-lives, and poor aqueous solubility. In this study, hydroxyethyl cellulose-grafted-2-acrylamido-2-methylpropane sulfonic acid (HEC-g-AMPS) hydrogels were successfully prepared for the controlled release of Radix Paeonia Alba-solid dispersion (RPA-SD). A total of 43 compounds were identified in RPA-SD using UHPLC-Q-TOF-MS analysis. The hydrogel network formation was confirmed by FTIR, TGA, DSC, XRD, and SEM. Hydrogels' swelling and drug release were slightly higher at pH 1.2 (43.31% swelling, 81.70% drug release) than at pH 7.4 (27.73% swelling, 72.46% drug release) after 48 h. The gel fraction, drug release time and mechanical strength of the hydrogels increased with increased polymer and monomer concentration. Furthermore, the hydrogels were porous (84.15% porosity) and biodegradable (8.9% weight loss per week). Moreover, the synthesized hydrogels exhibited excellent antimicrobial and antioxidative properties.

Direct current conduction mechanism in the methyl acrylate–vinyl acetate composite thin films

Plasma polymerized (PP) methyl acrylate (MA) and vinyl acetate (VA) composite thin films were deposited onto glass substrate varying MA and VA monomer concentrations. Thickness of the composite polymers is observed to vary on the MA and VA monomer ratios, where MA is found more reactive. The FESEM images of the composite polymers show better surface morphology compared to those of the homopolymers. Appearance of broad absorption bands in the FTIR spectra of polymer indicates the structural changes compared to monomer during polymerization. Thermogravimetric analysis and differential scanning calorimetry indicate that composite films are thermally more stable (up to 617 K) compared to homopolymer thin films (563 K). The current density versus voltage (J–V) characteristics of PP(MA-VA) composite films (sandwiched between aluminum electrodes) with different MA and VA ratios showed that the J values of the composite films gradually increase with elevating VA monomer and also with temperature (298–373 K). On the other hand, this value increases with decreasing the thickness of the composite films, which complies with the other studies. The conduction of the thickness-dependent composite films showed Ohmic in nature in the lower voltage region (< 10 V) while the space charge-limited conduction is found to be dominated in the higher voltage region (> 10 V) operating over the entire range of temperature. The activation energy at room temperature was found to be ~ 0.019 eV in the Ohmic region and 0.260 eV in the non-Ohmic region.

In-use stability of ready-to-administer daratumumab subcutaneous injection solution in plastic syringes

ObjectiveIn multiple myeloma patients, daratumumab is preferably injected subcutaneously. The summary of product characteristics of daratumumab subcutaneous injection solution specifies physicochemical stability for the prepared syringe for 24 hours at...

A comprehensive evaluation of arginine and its derivatives as protein formulation stabilizers

Arginine and its derivatives (such as arginine ethyl ester and acetyl arginine) have varying degrees of protein aggregation suppressor effect across different protein solutions. To understand this performance ambiguity, we evaluated the activity of arginine, acetyl arginine, and arginine ethyl ester for aggregation suppressor effect against human intravenous immunoglobulin G (IgG) solution at pH 4.8. Both arginine and its cationic derivative arginine ethyl ester in their hydrochloride salt forms significantly reduced the colloidal and conformational stability (reduced kd and Tm) of IgG. Consequently, the monomer content was decreased with an increase in subvisible particulates after agitation or thermal stress. Furthermore, compared to arginine, arginine ethyl ester with one more cationic charge and hydrochloride salt form readily precipitated IgG at temperatures higher than 25 °C. On the contrary, acetyl arginine, which mostly exists in a neutral state at pH 4.8, efficiently suppressed the formation of subvisible particles retaining a high amount of monomer owing to its higher colloidal and conformational stability. Concisely, the charged state of additives significantly impacts protein stability. This study demonstrated that contrary to popular belief, arginine and its derivatives may either enhance or suppress protein aggregation depending on their net charge and concentration.

Thermal safety and overall kinetics for methyl methacrylate solution polymerization via on-line process analytical technology

Polymethyl methacrylate (PMMA) is widely used, but its polymerization process is highly hazardous and the relevant thermal hazards have not been adequately investigated. Herein, the thermal safety and kinetic mechanisms of methyl methacrylate (MMA) polymerization are explored. The effect of monomer concentration on the exothermic characteristics is first investigated using a reaction calorimeter. The results indicate that the exothermic behavior of this reaction is significantly influenced by the monomer concentration. Meanwhile, a quantitative relationship between the specific enthalpy and monomer concentration is determined. Moreover, overall rate expression is developed by a rapid quantitative method to further elucidate the quantitative dependence of reaction rate on the process conditions. Subsequently, adiabatic experiment is performed to reveal the thermal controllability of this reaction. Finally, risk level is ascertained to propose constructive countermeasures. This work provides guidance for the safe operation of MMA polymerization, and the methodology also furnishes universal solutions for analogous reactions.

Enzymatic hydrolysis of single-use bioplastic items by improved recombinant yeast strains

Single-use bioplastic items pose new challenges for a circular plastics economy as they require different processing than petroleum-based plastics items. Microbial and enzymatic recycling approaches could address some of the pitfalls created by the influx of bioplastic waste. In this study, the recombinant expression of a cutinase-like-enzyme (CLE1) was improved in the yeast Saccharomyces cerevisiae to efficiently hydrolyse several commercial single-use bioplastic items constituting blends of poly(lactic acid), poly(1,4-butylene adipate-co-terephthalate), poly(butylene succinate) and mineral fillers. The hydrolysis process was optimised in controlled bioreactor configurations to deliver substantial monomer concentrations and, ultimately, 29 to 78% weight loss. Product inhibition studies and molecular docking provided insights into potential bottlenecks of the enzymatic hydrolysis process, while FT-IR analysis showed the preferential breakdown of specific polymers in blended commercial bioplastic items. This work constitutes a step towards implementing enzymatic hydrolysis as a circular economy approach for the valorisation of end-of-life single-use bioplastic items.

Column-free optical deconvolution of intrinsic fluorescence for a monoclonal antibody and its product-related impurities

The quantification of monoclonal antibody (mAb) aggregates and fragments using high pressure liquid chromatography-size exclusion chromatography (HPLC-SEC) typically requires off-line measurements that are time-consuming and therefore not compatible with real-time monitoring. However, it has been crucial to manufacturing and process development, and remains the industrial standard in the assessment of product-related impurities. Here we demonstrate that our previously established intrinsic time-resolved fluorescence (TRF) approach can be used to quantify the bioprocess critical quality attribute (CQA) of antibody product purity at various stages of a typical downstream process, with the potential to be developed for in-line bioprocess monitoring. This was directly benchmarked against industry-standard HPLC-SEC. Strong linear correlations were observed between outputs from TRF spectroscopy and HPLC-SEC, for the monomer and aggregate-fragment content, with R2 coefficients of 0.99 and 0.69, respectively. At total protein concentrations above 1.41 mg/mL, HPLC-SEC UV-Vis chromatograms displayed signs of detector saturation which reduced the accuracy of protein quantification, thus requiring additional sample dilution steps. By contrast, TRF spectroscopy increased in accuracy at these concentrations due to higher signal-to-noise ratios. Our approach opens the potential for reducing the time and labour required for validating aggregate content in mAb bioprocess stages from the several hours required for HPLC-SEC to a few minutes per sample.

Electrochemical DNA Sensor for Valrubicin Detection Based on Poly(Azure C) Films Deposited from Deep Eutectic Solvent.

A novel electrochemical DNA sensor was developed for the detection of the anthracycline drug, valrubicin, on the base of poly(Azure C) electropolymerized from the deep eutectic solvent reline and covered with adsorbed DNA from calf thymus. Biosensor assembling was performed by multiple scanning of the potential in one drop (100 µL) of the dye dissolved in reline and placed on the surface of a screen-printed carbon electrode. Stabilization of the coating was achieved by its polarization in the phosphate buffer. The electrochemical characteristics of the electron transfer were determined and compared with a similar coating obtained from phosphate buffer. The use of deep eutectic solvent made it possible to increase the monomer concentration and avoid using organic solvents on the stage of electrode modification. After the contact of the DNA sensor with valrubicin, two signals related to the intrinsic redox activity of the coating and the drug redox conversion were found on voltammogram. Their synchronous changes with the analyte concentration increased the reliability of the detection. In the square-wave mode, the DNA sensor made it possible to determine from 3 µM to 1 mM (limit of detection, 1 µM) in optimal conditions. The DNA sensor was successfully tested in the voltammetric determination of valrubicin in spiked artificial urine, Ringer-Locke solution mimicking plasma electrolytes and biological samples (urine and saliva) with a recovery of 90-110%. After further testing on clinical samples, it can find application in the pharmacokinetics studies and screening of new drugs' interaction with DNA.

Exploiting the Monomer-Feeding Mechanism of RAFT Emulsion Polymerization for Polymerization-Induced Self-Assembly of Asymmetric Divinyl Monomers.

We exploited the monomer-feeding mechanism of reversible addition-fragmentation chain transfer (RAFT) emulsion polymerization to achieve the successful polymerization-induced self-assembly (PISA) of asymmetric divinyl monomers. Colloidally stable cross-linked block copolymer nanoparticles with various morphologies, such as vesicles, were directly prepared at high solids. Morphologies of the cross-linked block copolymer nanoparticles could be controlled by varying the monomer concentration, degree of polymerization (DP) of the core-forming block, and length of the macro-RAFT agent. X-ray photoelectron spectroscopy (XPS) characterization confirmed the presence of unreacted vinyl groups within the obtained block copolymer nanoparticles, providing a landscape for further functionalization via thiol-ene chemistry. Finally, the obtained block copolymer nanoparticles were employed as additives to tune the mechanical properties of hydrogels. We expect that this study not only offers considerable opportunities for the preparation of well-defined cross-linked block copolymer nanoparticles, but also provides important insights into the controlled polymerization of multivinyl monomers.

Support-free interfacial polymerized polyamide membrane on a macroporous substrate to reduce internal concentration polarization and increase water flux in forward osmosis

Macroporous substrates have great potential in the development of high performance thin film composite forward osmosis (TFC FO) membranes. This paper reports on the preparation of TFC FO membrane via support-free interfacial polymerization (SFIP) technology on a macroporous substrate. SFIP technology can effectively break the bottleneck of conventional interfacial polymerization (IP) technology, which makes it difficult to form a complete polyamide (PA) film on the macroporous substrate. Briefly, the complete PA film is formed at the free water-organic phase interface and then attached to the macroporous substrate by vacuum filtration. The monomer concentration and filtration pressure were adjusted to form the optimal SFIP-PA film. Meanwhile, we chose a macroporous polyvinylidene fluoride (PVDF) microfiltration substrate and screened the pore size to reduce the structural parameters and then the internal concentration polarization, which caused the improvement of water flux. The performance of SFIP-PVDF membranes was investigated and discussed. Under the AL-FS mode with DI water and 1.0 M NaCl solution as the feed solution and draw solution, respectively, the SFIP-PVDF membrane, which used a macroporous PVDF substrate with a pore size of 0.45 μm exhibited a water flux (20 L/m2·h) and a reverse salt flux (2.5 g/m2·h). Besides, the membrane showed good stability in the 72 h test. The specific salt flux (Js/Jw) of SFIP-PVDF membranes was much lower than that of IP-PVDF membranes prepared via IP technology, which were incomplete and defective, suggesting that SFIP technology was superior to IP technology. This work effectively exploits the potential of macroporous substrates for the development of high performance TFC FO membranes and provides an insight into the high performance FO membrane design.

Comparative transcriptome analysis of major lodging resistant factors in hulless barley.

Hulless barley (Hordeum vulgare L. var. nudum Hook. f.), belonging to the genus Gramineae, has high and steady output and thus considered as a principal food crop by Tibetan people. Hulless barley grain can be used for food, brewing, and functional health product development, while its straw serves as an essential supplementary forage and is a crucial cereal crop. Lodging can reduce the yield and quality of barley grain and straw, and it hinders mechanical harvesting. It is a significant factor affecting high and stable yields of barley. Unlike other Poaceae plants (such as rice, wheat), hulless barley is mainly grown in high-altitude regions, where it is susceptible to low temperatures, strong winds, and heavy rainfall. As a result, its stem lodging resistance is relatively weak, making it prone to lodging during the growth period. In this study, we observed that the lignin concentration and the contents of lignin monomers (H, S, and G), and neutral detergent fibre of the lodging-resistant variety Kunlun14 were substantially greater than those of the lodging-sensitive variety Menyuanlianglan. We performed the weighted gene co-expression network analysis (WGCNA) and Short Time-series Expression Miner (STEM) analysis of both the lodging-resistant and lodging-sensitive varieties. Through transcriptome sequencing analysis at different developmental stages, combined with the previously annotated genes related to lodging resistance, a total of 72 DEGs were identified. Among these DEGs, 17 genes were related to lignin, cellulose, and hemicellulose synthesis or regulation, including five transcription factors about NAC, MYB and WRKY. Our results provide a basis for further exploring the molecular mechanism of stem lodging resistance in hulless barley and provide valuable gene resources for stem lodging resistance molecular breeding.

Blueberry Wine Aging: Influence of Bottle Storage Time on Color, Anthocyanin Monomers, and Antioxidant Activity

In this paper, the influence of bottle storage time on different blueberry wines has been studied. Four blueberry wines with different fruit weight/sugar solution volume ratios and different fermentation times were stored. The storage was conducted for 12 months in darkness and at a constant temperature of 4°C. All the wines showed a similar behavior during the 12-month study period. The concentration of anthocyanins decreased significantly after the storage period. Wines obtained through partial fermentation showed a low concentration of anthocyanin monomers, and in the case of wines from total fermentation, no anthocyanin monomers could be identified. However, the wines at 12 months of storage exhibited a significant contribution to red color. The color intensity experienced a sharp decrease from 0 to 4 months, remaining unchanged until 12 months. Moreover, antioxidant activity increased during the storage process from 0 to 4 months and then remained relatively stable up to 12 months.

Cydonia oblonga-Seed-Mucilage-Based pH-Sensitive Graft Copolymer for Controlled Drug Delivery-In Vitro and In Vivo Evaluation.

The primary objective of this study was to assess the potential utility of quince seed mucilage as an excipient within a graft copolymer for the development of an oral-controlled drug delivery system. The Cydonia oblonga-mucilage-based graft copolymer was synthesized via a free radical polymerization method, employing potassium per sulfate (KPS) as the initiator and N, N-methylene bisacrylamide (MBA) as the crosslinker. Various concentrations of monomers, namely acrylic acid (AA) and methacrylic acid (MAA), were used in the graft copolymerization process. Metoprolol tartarate was then incorporated into this graft copolymer matrix, and the resultant drug delivery system was subjected to comprehensive characterization using techniques such as Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The swelling behavior of the drug delivery system was evaluated under different pH conditions, and in vitro drug release studies were conducted. Furthermore, pharmacokinetic parameters including the area under the curve (AUC), maximum plasma concentration (Cmax), time to reach Cmax (Tmax), and half-life (t1/2) were determined for metoprolol-loaded hydrogel formulations in rabbit plasma, and these results were compared with those obtained from a commercially available product. The key findings from the study include observations that higher concentrations of acrylic acid (AA) and Cydonia oblonga mucilage (CM) in the graft copolymer enhanced swelling, while the opposite trend was noted at elevated concentrations of methacrylic acid (MAA) and N, N-methylene bisacrylamide (MBA). FTIR analysis confirmed the formation of the graft copolymer and established the compatibility between the drug and the polymer. SEM imaging revealed a porous structure in the prepared formulations. Additionally, the swelling behavior and drug release profiles indicated a pH-sensitive pattern. The pharmacokinetic assessment revealed sustained release patterns of metoprolol from the hydrogel network system. Notably, the drug-loaded formulation exhibited a higher Cmax (156.48 ng/mL) compared to the marketed metoprolol product (96 ng/mL), and the AUC of the hydrogel-loaded metoprolol was 2.3 times greater than that of the marketed formulation. In conclusion, this study underscores the potential of quince seed mucilage as an intelligent material for graft-copolymer-based oral-controlled release drug delivery systems.

Combined ultrasound and low temperature pretreatment improve the content of anthocyanins, phenols and volatile substance of Merlot red wine

Ultrasound combined with low temperature treatment is a new food processing technology. In this study, low temperature, three ultrasound power levels, and their combinations were adopted in the must before fermentation to study their effects on Merlot red wine. The results showed that ultrasound combined with low temperature pretreatment increased the total and monomer contents of anthocyanins and phenols, affected the color of the wine, and significantly increased its antioxidant capacity. In particular, 240 W of ultrasound combined with low temperature pretreatment reduced the bad odors (caprylic acid, benzaldehyde, and 1-ethanol content) and improved the flower and fruit aroma (1-octanol and phenethyl acetate), as well as the aftertaste, thus improving the quality of the wine. Ultrasound combined with low temperature pretreatment positively affected the quality of Merlot red wine.

Preparation and properties of flexible integrated cathode and electrolyte all-gel zinc-air batteries

Zinc-air batteries (ZABs) are of great interest in meeting the growing demand for flexible portable electronics due to their high energy density and low cost. In this paper, the interfacial dry crosslinking strategy is adopted, in which the dehydrated air cathode spontaneously absorbs water from the surface and inside of the electrolyte under the combined action of osmotic pressure and hydrophilic amide group, and the full gel integrating cathode and electrolyte is obtained by the interfacial dry crosslinking method of hydrogen bond adsorption. After water absorption, the conductive gel dry film electrode softens again, and a fusion interface is formed between the electrode and the electrolyte, and the integrated full gel is the best material for flexible batteries, which plays a vital role in the mechanical and electrochemical properties of the battery. In this paper, a polyacrylamide-based (PAM) all-in-one full gel with an optimal monomer content of 30 wt% is synthesized and used for bendable flexible packaging ZAB. The prepared ZAB exhibits good cycle stability of 177 h, excellent battery rate performance, stable discharge performance (high gram capacity of 785.16 mAh g−1), relatively high maximum power density (111.0 mW cm−2), and low interfacial contact impedance. With this 30 wt% all-in-one gel assembly soft pack ZAB can power a wide range of electronic devices and exhibit excellent flexibility in a wide range of bending conditions.

Preparation of Rechargeable Antibacterial Polypropylene/N-Halamine Materials Based on Melt Blending and Surface Segregation.

Polypropylene (PP) has been widely used in health care and food packaging fields, however, it lacks antibacterial properties. Herein, we prepared the polymeric antibacterial agents (MPP-NDAM) by an in situ amidation reaction between 2,4-diamino-6-dialkylamino-1,3,5-triazine (NDAM) and maleic anhydride grafted polypropylene (MPP) using the melt grafting method. The effects of reaction time and monomer content on the grafting degree of N-halamine were investigated, and a grafting degree of 4.86 wt % was achieved under the optimal reaction conditions. PP/MPP-NDAM composites were further obtained by a melt blending process between PP and MPP-NDAM. With the adoption of surface segregation technology, the content of N-halamine structure on the surface of PP/MPP-NDAM composites was significantly increased. The antibacterial tests showed that the PP/MPP-NDAM composite could achieve 99.9% bactericidal activity against 1.0 × 107 CFU/mL of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) within 10 and 5 min of contact, respectively. The antibacterial effect became more pronounced with the prolongation of chlorinated time, and it could achieve 99.9% bactericidal activity against E. coli within merely 1 min of contact.

Trifunctional Linkers Enable Improved Visualization of Actin by Expansion Microscopy.

Expansion microscopy (ExM) revolutionized the field of super-resolution microscopy by allowing for subdiffraction resolution fluorescence imaging on standard fluorescence microscopes. However, it has been found that it is hard to visualize actin filaments efficiently using ExM. To improve actin imaging, multifunctional molecules have been designed with moderate success. Here, we present optimized methods for phalloidin conjugate grafting that have a high efficiency for both cellular and tissue samples. Our optimized strategy improves anchoring and signal retention by ∼10 times. We demonstrate the potential of optimized trifunctional linkers (TRITON) for actin imaging in combination with immunolabeling using different ExM protocols. 10X ExM of actin labeled with optimized TRITON enabled us to visualize the periodicity of actin rings in cultured hippocampal neurons and brain slices by Airyscan confocal microscopy. Thus, TRITON linkers provide an efficient grafting method, especially in cases in which the concentration of target-bound monomers is insufficient for high-quality ExM.