Solute Solvent Research Articles

Multi-temperature charge scaling of ionic solvents: Disparate responses of thermodynamic properties

Charge scaling as a treatment to effectively include the intermolecular charge transfer and polarization effects is widely applied in molecular modelling of ionic solvents. While the charge scaling factor of 0.8 is picked as a generally applicable solution usable in many computational works, in this work based on extremely precise molecular simulations of bulk solvents and nonequilibrium Hamiltonian switching, we highlight the fact that the general 0.8 selection of the charge scaling factor could be a solution specific to the room-temperature condition that most ionic-liquids studies perform. When the environmental condition varies, this ‘general’ recommendation could sometimes lead to huge deviations. The situation is further complicated by the disparate responses of different properties (bulk density and solvation free energy) in the charge scaling space and along the temperature ladder. The driving force triggering the disparate responses could be attributed to the difference between interaction components involved in different thermodynamic properties, i.e., solvent–solvent interactions for bulk density and the additional solute–solvent interaction in the solvation process. A caution hinted by these observations is the necessity of condition- and property-specific parameter adjustment in practical situations.

Dispersion of Single-Walled Carbon Nanotubes by Aromatic Cyclic Schiff Bases via Non-Covalent Interactions.

One of the challenging issues that hinders the application of single-walled carbon nanotubes (SWCNTs) is the poor solubility and the inevitable formation of bundles. Efforts still need to be made towards solving the problem. Herein, we report a non-covalent strategy to disperse aggregated SWCNTs by aromatic cyclic Schiff bases assisted by ultrasonic techniques. The aromatic cyclic Schiff base (OMM) was synthesized via Schiff base reactions, and the molecular structure was determined by ATR-FT-IR, solid-state 13C-NMR, and HRMS. Although the yielded product showed poor solubility in aqueous solution and organic solvents, it could interact with and disperse the aggregated SWCNTs in dimethyl formamide (DMF) under the condition of ultrasound. UV-vis-NIR, FL, Raman spectra, AFM, and TEM, along with computer simulations, provide evidence for the interactions between OMM molecules and SWCNTs and the dispersion thereof. The semiconductive (7,5), (8,6), (12,1), and (9,7)-SWCNTs expressed a preference for dissolution. The capability of dispersion is contributed by π-π, C-H·π, and lone pair (lp)·π interactions between OMM and SWCNTs based on the simulated results. The present non-covalent strategy could provide inspiration for preparing organic cyclic compounds as dispersants for SWCNTs and then facilitate their further utilization.

Unveiling the conformational landscape of tizanidine and its effects on selective nucleation: Enabling controlled manipulation of polymorphs and solvates

The intricate relationship between conformational diversity and polymorphic nucleation is evident, while the underlying mechanisms remain unclear. In this work, tizanidine (TZND) was selected as the model compound to investigate its selective nucleation behavior and the association between conformations and polymorphs. Crystallization experiments were conducted using TZND in seven solvents, resulting in two polymorphs and four solvates, five of which are reported for the first time. Quantum chemical calculations were employed to explore the conformational landscape of TZND. Furthermore, 2D nuclear Overhauser effect spectroscopy and molecular dynamics were utilized to analyze the predominant conformation and its evolution in different solvents with varying concentrations. The results revealed that the dominant conformation of TZND could nucleate directly in methanol and acetone, while a conformational transition occurred during nucleation in acetonitrile and dichloromethane. Additionally, proton transfer in DMSO, chloroform, and DMF resulted in the emergence of new conformational forms. Moreover, crystallographic analysis, spectroscopic studies and quantum chemical calculations were adopted to investigate the molecular mechanisms governing selective nucleation and the formation of polymorphs or solvates. The results indicated that the free energy and solute–solvent interaction energy at specific sites influence the dominant conformation and its evolution in the solution. Finally, the nucleation mechanisms of different polymorphs and solvates were proposed and discussed, illustrating an efficient and environmentally friendly regulation method through solvent switching.

Solubility determination, model evaluation, molecular simulation and thermodynamic analysis of Dehydroacetic acid in thirteen pure solvents

The solid–liquid equilibrium solubility of DHA in thirteen pure solvents (methanol, ethanol, n-propanol, isopropanol, n-pentanol, ethyl formate, ethyl acetate, N, N-dimethyl acetamide (DMA), N, N-dimethyl formamide (DMF), acetonitrile, acetone, 2-butanone, dimethyl sulfoxide (DMSO)) was determined at temperatures ranging from 288.15–323.15 K under local atmosphere by gravimetric method. The experimental results showed that the solubility of DHA was positively correlated with the rising of temperatures. Five thermodynamic models, including Ideal model, Apelblat model, λh model, NRTL model and Wilson model, were employed to fit the experimental data and Wilson model provided a better correlation. The KAT-LSER model and molecular dynamic simulations were also carried out to investigate the effects of solvent–solute interactions on solubility. Furthermore, the thermodynamic properties of the dissolution process were calculated and the results argued a spontaneous, exothermic and entropy-driven process.

Hollow fiber thin-film composite membrane regulated by macrocyclic polyamine molecules for high performance organic solvent nanofiltration

Organic solvent nanofiltration (OSN) technology has the potential to separate and purify organic solvents in high efficiency. The self-supporting structure and ease scaling-up merit of hollow fiber (HF) type membrane make it an attractive option for OSN application. Nevertheless, low solvent permeance is one of technical limitation in conventional HF OSN membranes due to their excessively dense separation layer and limited free volume. Herein, we propose a straightforward methodology to fabricate HF thin-film composite (TFC) OSN membranes having exceptional solvent permeance and solute rejection. This methodology is conducted through the incorporation of macrocyclic molecules, 1,4,7,10-tetraazacyclododecane (Cyclen), into the aqueous monomer solution of m-Phenylenediamine (MPD) during the interfacial polymerization to modulate the separation layer. In this way, the average pore size of the separation layer could be precisely enlarged and narrowed on a sub-nanometer scale. Consequently, the Cyclen-modulated HF TFC OSN membrane exhibits excellent separation performance, with a pure methanol permeance of 76.7 L m−2 h−1 MPa−1 and a pure ethanol permeance of 26.5 L m−2 h−1 MPa−1, which is nearly 60 % increase compared with the baseline TFC membrane, while the Rhodamine B (RDB) rejection only shows a neglectable decrease from 99.7 % to 99.6 % at optimal fabrication conditions. Furthermore, the optimal membrane exhibits remarkable solvent resistance, withstanding a 35 d immersion in N, N-dimethylformamide (DMF) at room temperature without a significant decline in RDB rejection. Additionally, the optimal membrane shows higher than 99 % rejection for Rifampicin (823 Da), which is considerable potential for applications in the separation and recovery of pharmaceuticals. In summary, incorporating macrocyclic polyamine Cyclen into the polyamide layer is a viable method for regulating the physical structure and strengthening the performance of HF OSN membrane.

A Hydrophilic Metal Azolate Coordination Polymer for In Situ Encapsulation of Haloalkane Dehalogenase with Enhanced Enzymatic Performance.

Encapsulating enzymes within metal-organic frameworks such as zeolitic imidazolate framework-8 (ZIF-8) has been demonstrated to enhance enzymatic performance under harsh conditions. However, by computer-aided analysis, we revealed that highly hydrophobic organic ligands and unfavorable metal ions could greatly impair the activity of haloalkane dehalogenase DhaA by directly interacting with the catalytic sites, causing an extremely low activity of DhaA after encapsulating within ZIF-8. We also found that the presence of a protecting polymer could protect DhaA from the damage of organic ligands and metal ions and that a positively charged amino acid could increase the DhaA activity. Based on the simulations and experimental observations, we have designed to coencapsulate DhaA with poly(vinylpyrrolidone) (PVP) and lysine (Lys) within the amorphous Co-based metal azolate coordination polymer (CoCP). The as-prepared immobilized enzyme (DhaA/PVP/Lys@CoCP) exhibited significantly increased activity (91.5 times higher than that of DhaA@ZIF-8), dramatically enhanced thermostability at 50-70 °C, greatly improved catalytic performance in several organic solvent solutions, and good recyclability (over 75% of the initial activity after 10 cycles). The superiority of the immobilized enzyme was also demonstrated with a substrate frequently detected in the real world. In addition to the protective effect of PVP and positive effect of Lys, experimental and computational investigations unveiled other two favorable aspects that contributed to the enhanced enzymatic performance: (1) high hydrophilicity of the immobilization material and (2) the use of Co2+ with a minimal negative effect on DhaA. The research has thus provided a promising immobilized DhaA with favorable catalytic performance and great potential in industrial applications.

Fabrication of metallic titanium nanoparticles through ultrasonication assisted by electric current flow

This study was aimed at characterizing metallic Ti electrodes and nanoparticles fabricated from a titanium chloride/deep eutectic solvent (DES) solution by applying electric current between metallic Ti plates used as the anode and cathode under ultrasonic irradiation at room temperature. The cathode was not damaged during the flow of electric current, whereas the anode deteriorated to produce a nanoparticle colloidal solution. The nanoparticle size ranged from 5.3 to 12.2 nm. X-ray diffraction measurements revealed that the Ti nanoparticle powder exhibited a hexagonal crystal structure without any crystalline Ti oxide. However, X-ray photoelectron spectroscopy results indicated the presence of O. Furthermore, the metallic Ti nanoparticles were noted to be covered with Ti oxide layers. These layers acted as a physical barrier, protecting the metallic Ti nanoparticles against further oxidation by exposure to water and air.

Blueshift of the CN stretching vibration of acetonitrile in solution: computational and experimental study.

Acetonitrile, a polar molecule that cannot form hydrogen bonds on its own, interacts with solvent molecules mainly through the lone pair of its nitrogen atom and the π electrons of its CN triple bond [Correction added on 17 July 2024, after first online publication: Acetole has been changed to Acetonitrile in the preceeding sentence.]. Interestingly, acetonitrile exhibits an unexpected strengthening of the triple bond's force constant in an aqueous environment, leading to an upshift (blueshift) in the corresponding stretching vibration: this effect contrasts with the usual consequence of hydrogen bonding on the vibrational frequencies of the acceptor groups, that is, frequency redshift. This investigation elucidates this phenomenon using Raman spectroscopy to examine the behavior of acetonitrile in organic solvent, water, and silver ion aqueous solutions, where an even more pronounced upshift is observed. Raman spectroscopy is particularly well suited for analyzing aqueous solutions due to the minimal scattering effect of water molecules across most of the vibrational spectrum. Computational approaches, both static and dynamical, based on Density Functional Theory and hybrid functionals, are employed here to interpret these findings, and accurately reproduce the vibrational frequencies of acetonitrile in different environments. Our calculations also allow an explanation for this unique behavior in terms of electric charge displacements. On the other hand, the study of the interaction of acetonitrile with water molecules and metal ions is relevant for the use of this molecule as a solvent in both chemical and pharmaceutical applications.

Optical Rotation Predictions for Rigid Chiral Solute-Achiral Solvent 1:1 Complexes with the PCM Model

We computed specific optical rotations (ORs) in solution for forty-two solute–solvent combinations, involving seventeen chiral solutes and eight achiral solvents, using cam-B3LYP/aug-cc-PVTZ. Explicit solvent effects were considered by calculating Boltzmann-averaged ORs from multiple conformers of a 1:1 solute–solvent complex, with additional implicit solvation. The PCM solvation model correctly predicted OR signs for all combinations, while the “1:1 complex plus PCM“ schemes misjudged it in two cases. Norbornenone in cyclohexane displayed the largest absolute deviation, indicating an inadequate description of the cam-B3LYP functional’s delocalized electronic structure. Incorrect OR signs for fenchone in methanol with the ”1:1 complex plus PCM“ schemes underscored the limitations of our simplistic scheme, which incorporates explicit effects by averaging one-to-one interactions between solute and solvent. Considering computational costs, the ”1:1 complex plus PCM“ scheme may not be the optimal choice for our test set, as the PCM model alone suffices for accurate specific OR calculations in solution.

Hybrid Advanced Control Strategy for Post-Combustion Carbon Capture Plant by Integrating PI and Model-Based Approaches

Even though the energy penalties and solvent regeneration costs associated with amine-based absorption/stripping systems are important challenges, this technology remains highly recommended for post-combustion decarbonization systems given its proven capture efficacy and technical maturity. This study introduces a novel centralized and decentralized hybrid control strategy for the post-combustion carbon capture plant, aimed at mitigating main disturbances and sustaining high system performance. The strategy is rooted in a comprehensive mathematical model encompassing absorption and desorption columns, heat exchangers and a buffer tank, ensuring smooth operation and energy efficiency. The buffer tank is equipped with three control loops to finely regulate absorber inlet solvent solution parameters, preventing disturbance recirculation from the desorber. Additionally, a model-based controller, utilizing the model predictive control (MPC) algorithm, maintains a carbon capture yield of 90% and stabilizes the reboiler liquid temperature at 394.5 K by manipulating the influent flue gas to the lean solvent flowrates ratio and the heat duty of the reboiler. The hybrid MPC approach reveals efficiency in simultaneously managing targeted variables and handling complex input–output interactions. It consistently maintains the controlled variables at desired setpoints despite CO2 flue gas flow disturbances, achieving reduced settling time and low overshoot results. The hybrid control strategy, benefitting from the constraint handling ability of MPC, succeeds in keeping the carbon capture yield above the preset minimum value of 86% at all times, while the energy performance index remains below the favorable value of 3.1 MJ/kgCO2.

An Experimental Study on the Solubility of Betulin in the Complex Solvent Ethanol-DMSO

Betulin is a promising natural organic substance due to its antibacterial, fungicidal, and antitumor properties, as are their derivatives. The particle size of betulin can reach several tens of micrometers, and its thickness is several microns. There are various ways of processing betulin, but the most promising are solution methods (applying thin layers, impregnation, etc.). Application or impregnation of various materials is carried out using betulin; however, currently known solvents do not allow obtaining solutions with the necessary content of it. Since a number of direct solvents are already known for betulin, which provides only low-concentration solutions, the use of complex systems based on two solvents can become the optimal solution to the problem. The literature data show that the use of mixtures of solvents allows for the preparation of homogeneous solutions, for example, for natural polymers like cellulose, etc. This approach to obtaining solutions has become the basis for the processing of betulin. The use of a mixed solvent based on ethanol and DMSO for the preparation of betulin solutions has been proposed for the first time. The solubility of betulin in a mixture system with a ratio of components of 50 wt.% to 50 wt.% was studied, and a solubility curve was plotted. It is shown that the use of a two-component solvent makes it possible to transfer up to 10% of betulin into solution, which is almost twice as much as compared to already known solvents. The rheological properties of the obtained solutions have been studied. The viscosity of betulin solutions in a complex solvent depends on its content and temperature, so for 7% solutions at 70 °C, it is approximately 0.008 Pa*s. Applying betulin to the surface of the cardboard increases its hydrophobic properties and repellency.

Development of halochromic labels based on binary systems of cationic guar gum and κ-carrageenan loaded with alizarin red S for monitoring milk and seafood freshness

Monitoring of food quality, in particular, high-protein food quality, is an important component in ensuring food safety and human health. In this research, a feasible and easy solution casting and solvent evaporation strategy was adapted to fabricate alizarin red S (ARS)-loaded halochromic cationic guar gum (CGG) and κ-carrageenan (CAR) blend packaging labels to improve its good physical strength, multifunctional acid–base responsive characteristics, and water barrier properties. The findings indicated that incorporating CAR at 40% polymer solid mass achieved higher tensile strength (21.0 ± 1.77 MPa), water resistance (29.92 ± 6.61% solubility), and thermal stability, which can be attributed to good compatibility between CGG and CAR. The results obtained from FT-IR, XRD, and SEM analyses demonstrate that the incorporation of ARS exhibits non-covalent bonding with the polymer blend matrix through electrostatic interactions and hydrogen bonding, thus reducing its crystallinity and restructuring the CGG-CAR matrix disorderly. The prepared indicating label films presented visual recognition of ammonia and trimethylamine (TMA-N) at 0.008 mM in 6 min (the total color difference (ΔE) for TMA-N is＞11.89), and can be reused at least six times. Moreover, the color of ARS at different pH values remains persistent for at least 180 days. The practical applications show that the films, as indicator labels, can realize real-time, accurate, and visual dynamic monitoring of seafood (shrimp) and milk by engendering three chromatic stages discernible by the naked eye (fresh, spoiling, and spoiled). The ΔE for monitoring sub-fresh milk and shrimp reached as high as 14.91 and 13.32, respectively.

Volumetric, compressibility and viscometric studies on intermolecular interactions of NaC and NaDC with Emtricitabine and Lamivudine in aqueous medium at (298.15–313.15) K

Bile salts are bio-compatible natural amphiphiles having a significant role in pharmaceutical field as a solubility and permeability enhancer and possess a great biological importance for release and transport of nutrients due to dynamic micellization behavior. Hence, to unfold the interactional mystery of drug − bile salt system in the field of anti-retroviral drugs, we have aimed to investigate solute–solute and solute–solvent interactions of bile salts (NaC and NaDC) with anti-HIV drugs (Emtricitabine and Lamivudine) by using various techniques like volumetry, compressibility, and viscometry at temperature range (298.15 K-313.15 K) with a regular variation of 5 K. Experimental density and speed of sound data have been used to evaluate various physicochemical parameters such as apparent molar volume (φv), isentropic compressibility (κs), and apparent molar adiabatic compression (φκ). The CMC values of bile salts in pure water and aqueous solution of ECT and LMV at 298.15 K have also been evaluated from speed of sound data which corroborate well with our earlier conductivity study on these surfactants. The trends of φv, κs and φκ values for both NaC and NaDC with temperature and in presence of drugs (ECT/LMV) indicate strong solute–solvent interactions in studied system. The results are elucidated in terms of electrostatic and hydrophilic-hydrophobic interactions in bile salt-drug-water system which is confirmed by co-sphere overlap model. Comparatively, NaC offers strong interactions with both drugs due to more hydrophilic character than NaDC. Similarly, out of ECT and LMV, ECT shows strong solute–solvent interactions with both bile salts due to more hydrophilic character than LMV. Relative viscosity parameter (ηr) determined from viscosity measurements further supports above results. This interactional knowledge of bile salts with ECT and LMV would be beneficial to develop a better mechanism in pharmacy for enhancing efficacy and permeability of anti-HIV drugs by using bile salts as a drug delivery agent.

Unveiling the dissolution behavior of letrozole in fourteen pure solvents: Insights from experiments and molecular simulations

The dissolution behavior of an active pharmaceutical ingredient (API) in different solvents is of great importance for the design and optimization of its crystallization process. In this study, the solubility of letrozole in fourteen pure solvents was determined using a gravimetric method within the temperature range of 283.15–323.15 K at atmospheric pressure. The results demonstrate a significant correlation between letrozole’s dissolution behavior and the molecular structure (carbon chain length and presence of branched chains) and properties (dielectric constant and cohesive energy density) of the solvent. Solubility analysis and simple crystallization experiments suggest that acetonitrile may serve as a suitable solvent for the cooling crystallization of letrozole. To enhance the applicability of solubility data, five mathematical models were employed for data fitting. In addition, the Van’t Hoff equation was utilized to calculate the apparent thermodynamic properties of the letrozole dissolution process. Furthermore, molecular simulations were conducted to investigate the dissolution behavior of letrozole in different solvents, revealing distinct patterns of interaction between solute and solvent molecules. Specifically, in alcohol solvents, alcohol ether solvents, and acetonitrile, solute molecules interact with solvent molecules primarily as hydrogen bond acceptors, whereas the opposite behavior is observed in ester solvents and acetone. Binding energy, radial distribution function (RDF), and coordination number (CN) analyses effectively elucidate the dissolution behavior of letrozole in solvents of the same category, indicating that stronger solute–solvent interactions result in higher solubility. A comprehensive examination of solute–solvent and solvent–solvent interactions offers a rational explanation for letrozole’s dissolution behavior in solvents of different categories, highlighting the decisive impact of solvent–solvent interactions, particularly in alcohol solvents and acetone.

Effect of methyl substitution on hydrogen bond structure of anthocyanin

AbstractIn nature, hydrogen bonding is a common physical occurrence that has a significant impact on the surroundings of anthocyanins. Water molecules will create hydrogen bonds with anthocyanin molecules in various configurations, but the characteristics of these hydrogen bonds will change. Varied hydrogen bonding characteristics have varied impacts on solvent solutions. This research analyzes the differences in hydrogen bonding qualities caused by different methyl structures, as well as the underlying explanations. In this study, the cyanidin and peonidin structures of anthocyanin molecules were calculated in various stable hydrogen bond configurations using the density functional theory B3LYP/6‐31G(d,p), combined with information from the infrared spectroscopy spectrum, atoms in molecules analysis, interaction energy E, and intermolecular hydrogen bond length. The hydrogen bond structure that is the most stable is determined by analyzing it, as well as the effects of replacing the hydroxyl group with a methyl group and any potential underlying causes. Future anthocyanins research can benefit from the precise theoretical reference that this study can offer.

Noncovalent Interaction Guided Precise Photoluminescence Regulation of Gold Nanoclusters in Both Isolate Species and Aggregate States

AbstractDesigning luminophores bright in both isolate species and aggregate states is of great importance in many emerging cutting‐edge applications. However, the conventional luminophores either emit in isolate species but quench in aggregate state or emit in aggregate state but darken in isolate species. Here we demonstrate that the precise regulation of noncovalent interactions can realize luminophores bright in both isolate species and aggregate states. It is firstly discovered that the intra‐cluster interaction enhances the emission of atomically precise Au25(pMBA)18 (pMBA=4‐mercaptobenzoic acid), a nanoscale luminophore, while the inter‐cluster interaction quenches the emission. The emission enhancing strategies are then well‐designed by both introducing exogenous substances to block inter‐cluster interaction and surface manipulation of Au25(pMBA)18 at the molecular level to enhance intra‐cluster interaction, opening new possibilities to controllably enhance the luminophore's photoluminescence in both isolate species and aggregate states in different phases including aqueous solution, solid state and organic solvents.

Noncovalent Interaction Guided Precise Photoluminescence Regulation of Gold Nanoclusters in Both Isolate Species and Aggregate States.

Designing luminophores bright in both isolate species and aggregate states is of great importance in many emerging cutting-edge applications. However, the conventional luminophores either emit in isolate species but quench in aggregate state or emit in aggregate state but darken in isolate species. Here we demonstrate that the precise regulation of noncovalent interactions can realize luminophores bright in both isolate species and aggregate states. It is firstly discovered that the intra-cluster interaction enhances the emission of atomically precise Au25(pMBA)18 (pMBA=4-mercaptobenzoic acid), a nanoscale luminophore, while the inter-cluster interaction quenches the emission. The emission enhancing strategies are then well-designed by both introducing exogenous substances to block inter-cluster interaction and surface manipulation of Au25(pMBA)18 at the molecular level to enhance intra-cluster interaction, opening new possibilities to controllably enhance the luminophore's photoluminescence in both isolate species and aggregate states in different phases including aqueous solution, solid state and organic solvents.

Machine Learning Methods to Improve Crystallization through the Prediction of Solute–Solvent Interactions

Crystallization plays a crucial role in defining the quality and functionality of products across various industries, including pharmaceutical, food and beverage, and chemical manufacturing. The process’s efficiency and outcome are significantly influenced by solute–solvent interactions, which determine the crystalline product’s purity, size, and morphology. These attributes, in turn, impact the product’s efficacy, safety, and consumer acceptance. Traditional methods of optimizing crystallization conditions are often empirical, time-consuming, and less adaptable to complex chemical systems. This research addresses these challenges by leveraging machine learning techniques to predict and optimize solute–solvent interactions, thereby enhancing crystallization outcomes. This review provides a novel approach to understanding and controlling crystallization processes by integrating supervised, unsupervised, and reinforcement learning models. Machine learning not only improves product the quality and manufacturing efficiency but also contributes to more sustainable industrial practices by minimizing waste and energy consumption.

Nucleation behaviors of p-coumaric acid in four solvents from induction time and metastable zone width: experiments and simulations

The study of nucleation behaviors during crystallization is important for understanding the drug crystallization process. The induction time of p-coumaric acid (p-CA) was measured in four solvents at various levels of supersaturation. The kinetic parameters of nucleation (interfacial energy, critical nucleation radius, and critical Gibbs free energy) were estimated using the classical nucleation theory (CNT). The results showed that the nucleation difficulty of p-CA in the four solvents was in the order of ethyl acetate > acetone > ethanol > methanol. In addition, the metastable zone width (MSZW) of p-CA was determined in four solvents. The nucleation behaviors of p-CA were further expounded using self-consistent Nývlt-like model and modified Sangwal’s model. The results were consistent with those of CNT. To further reveal the impact of interactions between solvent and solute molecules on the nucleation behaviors of p-CA, molecular electrostatic potential surfaces (MEPs), Hirshfeld Surfaces (HS), and the radial distribution function (RDF) were performed. The investigation revealed that the intensity of solvent–solute interactions depended primarily on the strength of hydrogen bonding interactions. The RDF results showed that the magnitude of hydrogen bonding interactions of p-CA in the four solvents was in the following order: ethyl acetate > acetone > ethanol > methanol. As the hydrogen bonding interactions between p-CA and solvent molecules became stronger, the dissociation of solute molecules from solvent molecules became more difficult, leading to a wider MSZW and a lower nucleation rate.

Fabrication of 3D Polycaprolactone Macrostructures by 3D Electrospinning.

Building 3D electrospun macrostructures and monitoring the biological activities inside them are challenging. In this study, 3D fibrous polycaprolactone (PCL) macrostructures were successfully fabricated using in-house 3D electrospinning. The main factors supporting the 3D self-assembled nanofiber fabrication are the H3PO4 additives, flow rate, and initial distance. The effects of solution concentration, solvent, H3PO4 concentration, flow rate, initial distance, voltage, and nozzle speed on the 3D macrostructures were examined. The optimal conditions of 4 mL/h flow rate, 4 cm initial nozzle-collector distance, 14 kV voltage, and 1 mm/s nozzle speed provided a rapid buildup of cylinder macrostructures with 6 cm of diameter, reaching a final height of 16.18 ± 2.58 mm and a wall thickness of 3.98 ± 1.01 mm on one perimeter with uniform diameter across different sections (1.40 ± 1.10 μm average). Oxygen plasma treatment with 30-50 W for 5 min significantly improved the hydrophilicity of the PCL macrostructures, proving a suitable scaffold for in vitro cell cultures. Additionally, 3D images obtained by synchrotron radiation X-ray tomographic microscopy (SRXTM) presented cell penetration and cell growth within the scaffolds. This breakthrough in 3D electrospinning surpasses current scaffold fabrication limitations, opening new possibilities in various fields.