Prediction of solubility parameter from intrinsic viscosity

Inulin Can Improve Red Blood Cell Cryopreservation by Promoting Vitrification, Stabilizing Cell Membranes, and Inhibiting Ice Recrystallization

In transfusion medicine, the cryopreservation of red blood cells (RBCs) is of major importance. The organic solvent glycerol (Gly) is considered the current gold-standard cryoprotectant (CPA) for RBC cryopreservation, but the deglycerolization procedure is complex and time-consuming, resulting in severe hemolysis. Therefore, it remains a research hotspot to find biocompatible and effective novel CPAs. Herein, the natural and biocompatible inulin, a polysaccharide, was first employed as a CPA for RBC cryopreservation. The presence of inulin could improve the thawed RBC recovery from 11.83 ± 1.40 to 81.86 ± 0.37%. It was found that inulin could promote vitrification because of its relatively high viscosity and glass transition temperature (Tg'), thus reducing the damage during cryopreservation. Inulin possessed membrane stability, which also had beneficial effects on RBC recovery. Moreover, inulin could inhibit the mechanical damage induced by ice recrystallization during thawing. After cryopreservation, the RBC properties were maintained normally. Mathematical modeling analysis was adopted to compare the performance of inulin, Gly, and hydroxyethyl starch (HES) in cryopreservation, and inulin presented the best efficiency. This work provides a promising CPA for RBC cryopreservation and may be beneficial for transfusion therapy in the clinic.

Effect of Aprotic Solvents on the Microtensile Bond Strength of Composite Core and Fiber-Reinforced Composite Posts

This investigation evaluated the effects of aprotic solvents, i.e., tetrahydrofuran, pyridine, and morpholine, compared with hydrogen peroxide, on the surfaces of fiber-reinforced composite posts with a composite core based on the microtensile bond strength. In total, 150 FRC Postec Plus posts and 150 D.T. Light-Posts were randomly divided into three groups (non-thermocycling, 5000-cycle, and 10,000-cycle thermocycling groups). Each group was divided into five subgroups according to the post-surface treatment: C, non-treatment group; H2O2, immersed in 35% hydrogen peroxide; THF, immersed in tetrahydrofuran; PY, immersed in pyridine; and MP, immersed in morpholine. The treated specimens were placed in the bottom of a plastic cap and filled with a composite core material in preparation for the microtensile bond test. The data were evaluated using one-way ANOVA and Tukey's test (p < 0.05) as well as an independent t-test (p < 0.05). For the surface roughness, white light interferometry was used for measurement, and the mean surface roughness was analyzed via one-way ANOVA and Tukey's test (p < 0.05). The results showed that, under non-thermocycling conditions, the PY subgroup with D.T. Light-Post had the highest microtensile bond strength, followed by THF, MP, H2O2, and the control groups. For FRC Postec Plus, the PY group had the highest microtensile bond strength, followed by MP, THF, H2O2, and the control groups. Although the thermocycling conditions decreased the microtensile bond strength in all groups, the PY subgroup still had the highest value. An independent t-test revealed that even under all non-thermocycling and 5000- and 10,000-cycle thermocycling conditions, D.T. Light-Post in the PY subgroup displayed significantly higher microtensile bond strengths than FRC Postec Plus in the PY subgroup. While the surface roughness of the fiber-reinforced composite posts showed that the posts treated with pyridine possessed the highest surface roughness for each material type, In conclusion, as an aprotic solvent, pyridine generates the highest microtensile bond strength between the interfaces of composite cores and fiber-reinforced composite posts.

Molecular Simulation to Explore the Dissolution Behavior of Sulfur in Carbon Disulfide

Soluble sulfur (S₈) and insoluble sulfur (IS) have different application fields, and molecular dynamics simulation can reveal their differences in solubility in solvents. It is found that in the simulated carbon disulfide (CS₂) solvent, soluble sulfur in the form of clusters mainly promotes the dissolution of clusters through van der Waals interaction between solvent molecules (CS₂) and S₈, and the solubility gradually increases with the increase in temperature. However, the strong interaction between polymer chains of insoluble sulfur in the form of polymer hinders the diffusion of IS into CS₂ solvent, which is not conducive to high-temperature dissolution. The simulated solubility parameter shows that the solubility parameter of soluble sulfur is closer to that of the solvent, which is consistent with the above explanation that soluble sulfur is easy to dissolve.

Mixed Solvents in Multilayer Ceramic Capacitors (MLCC) Electronic Paste and Their Effects on the Properties of Organic Vehicle

The copper end paste used in multilayer ceramic capacitors sintered in nitrogen atmosphere leads to carbon residues of organic vehicles, which leads to a reduction in electrode conductivity and high scrap rate. With an attempt to leave no residue in the sintering, the compatibility of solvents and thickeners should be improved because it has an important influence on the hierarchical volatilization and carbon residue of organic vehicles. In this work, the volatility of different solvents was compared, and several solvents were mixed in a definite proportion to prepare an organic vehicle with polyacrylate resins. The hierarchical volatility and solubility parameters of mixed solvents were effectively adjusted by changing proportions of different components. The thermogravimetric curves of resins and organic vehicles were measured by thermogravimetric analyzer, and the effect of solubility parameter on the dissolvability of resins in the solvent and the residual of organic vehicles were studied. Results showed that the hierarchical volatilization of solvents can be obtained by mixing different solvents; the intrinsic viscosity of the organic vehicle is higher, and the thermal decomposition residue of polyacrylate resins is lower when the solubility parameters of mixed solvents and polyacrylate resins are closer. The low residual sintering of organic vehicles can be achieved by using a mixed solvent with hierarchical volatility and approximate solubility parameters as resins.

Exploring the application and mechanism of sodium hyaluronate in cryopreservation of red blood cells

The cryopreservation of red blood cells (RBCs) is essential for transfusion therapy and maintaining the inventory of RBCs units. The existing cryoprotectants (CPAs) have many defects, and the search for novel CPAs is becoming a research hotspot. Sodium hyaluronate (SH) is polymerized from sodium glucuronate and N-acetylglucosamine, which has good water binding capacity and biocompatibility. Herein, we reported for the first time that under the action of medium molecular weight sodium hyaluronate (MSH), the thawed RBCs recovery increased from 33.1 ​± ​5.8% to 63.2 ​± ​3.5%. In addition, RBCs functions and properties were maintained normally, and the residual MSH could be removed by direct washing. When MSH was used with a very low concentration (5% v/v) of glycerol (Gly), the thawed RBCs recovery could be increased to 92.3 ​± ​4.6%. In general, 40% v/v Gly was required to achieve similar efficiency. A mathematical model was used to compare the performance of MSH, PVA and trehalose in cryopreservation, and MSH showed the best efficiency. It was found that MSH could periodically regulate the content of intracellular water through the “reservoir effect” to reduce the damages during freezing and thawing. Moreover, MSH could inhibit ice recrystallization when combined with RBCs. The high viscosity and strong water binding capacity of MSH was also conducive to reducing the content of ice. This works points out a new direction for cryopreservation of RBCs and may promote transfusion therapy in clinic.

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MSH improved the RBCs recovery in cryopreservation.

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MSH can be removed directly after thawing.

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The properties and functions of RBCs were protected by MSH.

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High RBCs recovery is found using MSH with 5% v/v glycerol.

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The mathematical model is studied for the cryopreservation.

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The mechanism is proposed for cryopreservation using MSH.

New Insights on Solvent Implications in the Design of Materials Based on Cellulose Derivatives Using Experimental and Theoretical Approaches

The current paper presents a strategic way to design and develop materials with properties adapted for various applications from biomedicine to environmental applications. In this context, blends of (hydroxypropyl)methyl cellulose (HPMC) and poly(vinylpyrrolidone) (PVP) were obtained to create new materials that can modulate the membrane properties in various fields. Thus, to explore the possibility of using the HPMC/PVP system in practical applications, the solubility parameters in various solvents were initially evaluated using experimental and theoretical approaches. In this frame, the study is aimed at presenting the background and steps of preliminary studies to validate the blends behavior for targeted application before being designed. Subsequently, the analysis of the behavior in aqueous dilute solution of HPMC/PVP blend offers information about the conformational modifications and interactions manifested in system depending on the structural characteristics of polymers (hydrophilicity, flexibility), polymer mixtures composition, and used solvent. Given this background, based on experimental and theoretical studies, knowledge of hydrodynamic parameters and analysis of the optimal compositions of polymer mixtures are essential for establishing the behavior of obtained materials and validation for most suitable applications. Additionally, to guarantee the quality and functionality of these composite materials in the targeted applications, e.g., biomedical or environmental, the choice of a suitable solvent played an important role.

Microwave-assisted organic swelling promotes fast and efficient delamination of waste printed circuit boards

A large amount of waste printed circuit boards (WPCBs) that contain valuable metals, namely gold and copper, are produced annually. WPCBs are constituted by a multi-layer structure reinforced by a brominated epoxy resin (BER), which is very difficult to separate into the metallic and non-metallic components. The main aim of this work was to evaluate the ability of microwave for assisting in the delamination of WPCBs by organic swelling of the BER. Additionally, its performance was compared with other strategies (thermostatic and ultrasonic baths) previously described in the literature. Firstly, a library of solvents [dimethyl formamide (DMF), dimethyl acetamide (DMAc), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), cyclohexanone (CH), γ-butyrolactone (GBL), tetrahydrofurfuryl alcohol (TFA) and dimethyl malonate (DM)] was selected based on the calculation of Hansen solubility parameters plus others exclusion parameters and their performance to detach all components of WPCBs (25 mm²) was tested by microwave (200 °C for 10 min), thermostatic (153 °C for 10 min) and ultrasonic (60 °C for 25 h) baths. Microwave showed to be the most efficient approach and the delamination order for WPCBs was: NMP > DMSO >DMF > DMAc. Subsequent optimization of key parameters (dimensions of WPCBs and reaction time) were obtained: dimensions of 225 mm² using NMP (solid/liquid ratio of 300 g/L) at 200 °C with 2 cycles of 10 min. In conclusion, microwave-assisted swelling revealed to be more efficient and faster process to delaminate WPCBs into metallic and non-metallic components, which are important advantages when envisaging a future industrial waste management implementation.

QSPR modelling for intrinsic viscosity in polymer-solvent combinations based on density functional theory

Linear and nonlinear quantitative structure-property relationship (QSPR) models were developed based on a dataset with 65 polymer-solvent combinations. Seven quantum chemical descriptors, dipole moment, hardness, chemical potential, electrophilicity index, total energy, HOMO and LUMO orbital energies, were calculated with density functional theory at the B3LYP/6-31 G(d) level for polymers and solvents. Considering the strong correlation between intrinsic viscosity and weight, size, shape as well as topological structure of polymers and solvents, topological descriptors were also applied in this work. Meanwhile, the most appropriate polymer structure representation was investigated by considering 1-5 monomeric repeating units. The molecular descriptors were first screened by using the genetic algorithms-multiple linear regression (GA-MLR), with coefficient of determinations (r2) of 0.78 and 0.83 for the training set and the prediction set, respectively. The support vector machine model (SVM) model based on the selected descriptors subset showed a r2 value of 0.95 for the training set and 0.93 for the prediction set. All statistical results suggest that the established QSPR models have good predictability. Furthermore, a new test set obtained from the literature was used for further validation. The r2 values were 0.81 for the MLR model and 0.90 for the SVM model.

Molecular dynamics simulation of polystyrene copolymer with octyl short-chain branches in toluene

In this study, dimensional, conformational and dynamic behaviors of a short-chain branched styrene/1-octene copolymer chain with different 1-octene percentages, i.e., 0, 2, 4 and 6%, in toluene are investigated at the temperature of 298.15 K via molecular dynamics simulation. The chain dimensions and flexibility in the solvent are evaluated by calculating the radius of gyration (R_g), end-to-end distance (<r₀>), surface area (A_ch), and volume (V_ch) of the copolymer chain. The mean square displacement (MSD) and diffusivity coefficient for each copolymer chain are measured to determine its dynamic behavior and mobility in aromatic media. To consider the effect of increasing the 1-octene co-monomer percentage on the copolymer chain affinity to the solvent molecules, the interaction energy (E_int) and Flory-Huggins (FH) interaction parameter are calculated for each equilibrated solution model. The simulation results indicate that the co-monomer level increment in the copolymer structure reduces the chain R_g amount and its interaction with the solvent. The <r₀> of the chain increases up to 4% co-monomer content, while further co-monomer content decreases the <r₀> value. Additionally, the viscosity of the equilibrated dilute solutions is calculated via non-equilibrium molecular dynamics simulation (NEMD). Moreover, the steric hindrance of the copolymers and the solvent molecules capturing in the dilute solution is determined via radial distribution function (RDF) analysis. Helmholtz free energy and the system entropy changes are calculated to evaluate the tendency of the copolymer to the solvent molecules and its dilute solution irregularity, respectively. Graphical abstract The figure shows the variations trend of the poly(styrene-co-1-octene) chain dimensions in toluene aromatic solvent by increasing the 1-octene content (x), after the equilibration state. Red and blue colors represent the carbon atoms of the copolymer chain backbone and 1-octene side chains, respectively. The styrene rings and the hydrogen atoms of the chains were removed for better view.

A Novel Rheological Method to Assess Drug-Polymer Interactions Regarding Miscibility and Crystallization of Drug in Amorphous Solid Dispersions for Oral Drug Delivery

Solid dispersions provide a key technology to formulate poorly water-soluble drugs, and a main task of early development is appropriate selection of polymer. This study investigates the use of a novel rheology-based approach to evaluate miscibility and interactions of drugs with polymers regarding amorphous solid drug dispersions for oral administration. Tacrolimus was used as model drug and hydroxypropyl cellulose, ethylcellulose, Soluplus^®, polyethyleneglycol 6000, Poloxamer-188 (Koliphor-188), and Eudragit^® S100 were used as excipients. Solvent-based evaporation methods were used to prepare binary solid dispersions of drug and polymer. Data of the dilute solution viscosimetry were compared with in silico calculations of the Hansen solubility parameter (HSP), as well as phase separation/crystallization data obtained from X-ray diffraction and differential scanning calorimetry. HSP calculations in some cases led to false positive predictions of tacrolimus miscibility with the tested polymers. The novel rheology-based method provided valuable insights into drug-polymer interactions and likely miscibility with polymer. It is a rather fast, inexpensive, and robust analytical approach, which could be used complementary to in silico-based evaluation of polymers in early formulation development, especially in cases of rather large active pharmaceutical ingredients.

Tailor-made solvents for pharmaceutical use? Experimental and computational approach for determining solubility in deep eutectic solvents (DES)

A deep eutectic solvent (DES) is a mixture of two or more chemicals that interact via hydrogen bonding and has a melting point far below that of the individual components. DESs have been proposed as alternative solvents for poorly soluble active pharmaceutical ingredients (API). In this study, the solvation capacities of six deep eutectic solvents were compared to water and three conventional pharmaceutical solvents (PEG 300, ethanol and glycerol) for 11 APIs. The experimentally determined solubilities were compared to computational solubilities predicted by the Conductor-like Screening Model for Real Solvents (COSMO-RS). While the conventional pharmaceutical solvents PEG 300 and ethanol were the best solvents for the majority of the studied APIs, API-DES combinations were identified, which exceeded the API solubility found in the conventional pharmaceutical solvents. Furthermore, it was also possible to obtain high solubilities in the DESs relative to water, suggesting DESs to be potential solvents for poorly water soluble APIs. In addition, the relative increase in solubility found in the experimental data could be well predicted ab initio using COSMO-RS. Hence, COSMO-RS may in the future be used to reduce the experimental screening of potential DESs for a given API.

Application of the solubility parameter concept to assist with oral delivery of poorly water-soluble drugs – a PEARRL review

Objectives

Solubility parameters have been used for decades in various scientific fields including pharmaceutics. It is, however, still a field of active research both on a conceptual and experimental level. This work addresses the need to review solubility parameter applications in pharmaceutics of poorly water-soluble drugs.

Key findings

An overview of the different experimental and calculation methods to determine solubility parameters is provided, which covers from classical to modern approaches. In the pharmaceutical field, solubility parameters are primarily used to guide organic solvent selection, cocrystals and salt screening, lipid-based delivery, solid dispersions and nano- or microparticulate drug delivery systems. Solubility parameters have been applied for a quantitative assessment of mixtures, or they are simply used to rank excipients for a given drug.

Summary

In particular, partial solubility parameters hold great promise for aiding the development of poorly soluble drug delivery systems. This is particularly true in early-stage development, where compound availability and resources are limited. The experimental determination of solubility parameters has its merits despite being rather labour-intensive because further data can be used to continuously improve in silico predictions. Such improvements will ensure that solubility parameters will also in future guide scientists in finding suitable drug formulations.

Effect of the Cationic Block Structure on the Characteristics of Sludge Flocs Formed by Charge Neutralization and Patching

In this study, a template copolymer (TPAA) of (3-Acrylamidopropyl) trimethylammonium chloride (AATPAC) and acrylamide (AM) was successfully synthesized though ultrasonic-initiated template copolymerization (UTP), using sodium polyacrylate (PAAS) as a template. TPAA was characterized by an evident cationic microblock structure which was observed through the analyses of the reactivity ratio, Fourier transform infrared spectroscopy (FTIR), ¹H (¹³C) nuclear magnetic resonance spectroscopy (¹H (¹³C) NMR), and thermogravimetry/differential scanning calorimetry (TG/DSC). The introduction of the template could improve the monomer (AATPAC) reactivity ratio and increase the length and amount of AATPAC segments. This novel cationic microblock structure extremely enhanced the ability of charge neutralization, patching, and bridging, thus improving the activated sludge flocculation performance. The experiments of floc formation, breakage, and regrowth revealed that the cationic microblock structure in the copolymer resulted in large and compact flocs, and these flocs had a rapid regrowth when broken. Finally, the larger and more compact flocs contributed to the formation of more channels and voids, and therefore the specific resistance to filtration (SRF) reached a minimum.

On the Influence of Micro- and Macro-Cristalline Paraffins on the Physical and Rheological Properties of Crude Oil and Organic Solvents

The influence of micro- and macro-crystalline paraffins on the properties of crude oil and organic solvents was investigated. Micro-cristalline paraffins promote the most pronounced changes in the investigated physical and rheological properties of all tested solutions. The concentration of branched-alkanes in paraffins is the pivotal parameter that promotes these changes.