Improvement in the Predicted Partitioning of Alcohol and Polyethylene Oxide Groups Between Water and Octanol (logP) in Molecular Dynamics Simulations

Aggregation-Induced Emission (AIE) in Polymers: Effect of Polymer size on the Fluorescence of Low Molecular Weight PEG and PPG

Aggregation-induced emission (AIE) is a fascinating phenomenon where specific molecules exhibit enhanced fluorescence upon aggregation. This unique property has revolutionized the design and development of new fluorescent materials for different applications, from biosensors and organic light-emitting diodes (OLEDs) to biomedical imaging and diagnostics. Researchers are creating sensitive and selective sensing platforms, opening new avenues in material science and engineering by harnessing the potential of AIE. To expand the knowledge in this field, this study explored the aggregation-induced emission (AIE) properties of two polymers, namely polyethylene glycol (PEG) and polypropylene glycol (PPG) of low molecular weight (MW) using fluorescence spectroscopy and absorbance (UV). PEG-300 and PPG-725 were the most fluorescent polymers at UV of the ten investigated. Interestingly, AIE did not correlate linearly with molecular weight (MW), and monobutyl ether substitution in PEG with a similar MW substantially altered its AIE. Furthermore, fluorescence precisely quantified low polymer concentrations in water, and non-aqueous solvents suppressed AIE, suggesting potential for AIE manipulation. These findings enhance our understanding of AIE in polymers, fostering the development of novel materials for applications such as biosensors.

Computational and Experimental Models of Type III Lipid-Based Formulations of Loratadine Containing Complex Nonionic Surfactants

Type III lipid-based formulations (LBFs) combine poorly water-soluble drugs with oils, surfactants, and cosolvents to deliver the drugs into the systemic circulation. However, the solubility of the drug can be influenced by the colloidal phases formed in the gastrointestinal tract as the formulation is dispersed and makes contact with bile and other materials present within the GI tract. Thus, an understanding of the phase behavior of LBFs in the gut is critical for designing efficient LBFs. Molecular dynamics (MD) simulation is a powerful tool for the study of colloidal systems. In this study, we modeled the internal structures of five type III LBFs of loratadine containing poly(ethylene oxide) nonionic surfactants polysorbate 80 and polyoxyl hydrogenated castor oil (Kolliphor RH40) using long-timescale MD simulations (0.4-1.7 μs). We also conducted experimental investigations (dilution of formulations with water) including commercial Claritin liquid softgel capsules. The simulations show that LBFs form continuous phase, water-swollen reverse micelles, and bicontinuous and phase-separated systems at different dilutions, which correlate with the experimental observations. This study supports the use of MD simulation as a predictive tool to determine the fate of LBFs composed of medium-chain lipids, polyethylene oxide surfactants, and polymers.

Molecular Dynamics Simulations and Experimental Results Provide Insight into Clinical Performance Differences between Sandimmune® and Neoral® Lipid-Based Formulations

OBJECTIVE

Molecular dynamics (MD) simulations provide an in silico method to study the structure of lipid-based formulations (LBFs) and the incorporation of poorly water-soluble drugs within such formulations. In order to validate the ability of MD to effectively model the properties of LBFs, this work investigates the well-known cyclosporine A formulations, Sandimmune® and Neoral®. Sandimmune® exhibits poor dispersibility and its absorption from the gastrointestinal tract is enhanced when administered after food, whereas Neoral® disperses comparatively well and shows no food effect.

METHODS

MD simulations were performed of both LBFs to investigate the differences observed in fasted and fed conditions. These conditions were also tested using an in vitro experimental model of dispersion and digestion.

RESULTS

These MD simulations were able to show that the food effect observed for Sandimmune® can be explained by large changes in drug solubilization on addition of bile. In contrast, Neoral® is well dispersed in water or in simulated fasted conditions, and this dispersion is relatively unchanged on moving to fed conditions. These differences were confirmed using dispersion and digestion in vitro experimental model.

CONCLUSIONS

The current data suggests that MD simulations are a potential method to model the fate of LBFs in the gastrointestinal tract, predict their dispersion and digestion, investigate behaviour of APIs within the formulations, and provide insights into the clinical performance of LBFs.

Aqueous phase behavior of the PEO-containing non-ionic surfactant C12E6: A molecular dynamics simulation study

HYPOTHESIS

Non-ionic surfactants containing polyethylene oxide (PEO) chains are widely used in drug formulations, cosmetics, paints, textiles and detergents. High quality molecular dynamics models for PEO surfactants can give us detailed, atomic-scale information about the behavior of surfactant/water mixtures.

SIMULATIONS

We used two molecular dynamics force fields (FFs), 2016H66 and 53A6_DBW, to model the simple non-ionic PEO surfactant, hexaoxyethylene dodecyl ether (C₁₂E₆). We investigated surfactant/water mixtures that span the phase diagram of starting from randomly distributed arrangements. In some cases, we also started with prebuilt, approximate models. The simulations results were compared with the experimentally observed phase behavior.

FINDINGS

Overall, this study shows that the spontaneous self-assembly of PEO non-ionic surfactants into different colloidal structures can be accurately modeled with MD simulations using the 2016H66 FF although transitions to well-formed hexagonal phase are slow. Of the two FFs investigated, the 2016H66 FF better reproduces the experimental phase behavior across all regions of the C₁₂E_6/water phase diagram.

Comprehensive analysis of important parameters of choline chloride-based deep eutectic solvent pretreatment of lignocellulosic biomass

Choline chloride based deep eutectic solvents have showed great potential in lignocellulosic biomass pretreatment. In this study, for DES pretreatment with different hydrogen bond donners of different raw materials under different reaction conditions, multivariate analysis methods including principal component analysis and partial least squares analysis were used for reveal the pretreatment mechanism by evaluating the inner relationships among 42 key process factors. Furthermore, based on molecular simulation, the detailed relationships between key variables were further analyzed. Meanwhile, four-dimensional color graphs were used to intuitively reveal the synergistic influence of multivariate conditions variables on pretreatment effect to obtain better economic benefits and energy consumption indicators for DES pretreatment. The results showed that HBD hydrophilic ability, HBD polarity, HBD acidity, HBD ability to form hydrogen bonds, molar ratio of HBD to choline chloride and pretreatment severity had great influence on the Choline chloride based deep eutectic solvents pretreatment effect.

A Nonionic Polyethylene Oxide (PEO) Surfactant Model: Experimental and Molecular Dynamics Studies of Kolliphor EL

Polyethoxylated, nonionic surfactants are important constituents of many drug formulations, including lipid-based formulations. In an effort to better understand the behavior of formulation excipients at the molecular level, we have developed molecular dynamics (MD) models for the widely used surfactant Kolliphor EL (KOL), a triricinoleate ester of ethoxylated glycerol. In this work, we have developed models based on a single, representative molecular component modeled with 2 force field variations based on the GROMOS 53A6_DBW and 2016H66 force field parameters for polyethoxylate chains. To compare the computational models to experimental measurements, we investigated the phase behavior of KOL using nephelometry, dynamic light scattering, cross-polarized microscopy, small-angle X-ray scattering, and cryogenic transmission electron microscopy. The potential for digestion of KOL was also evaluated using an in vitro digestion experiment. We found that the size and spherical morphology of the KOL colloids at low concentrations was reproduced by the MD models as well as the growing interactions between the aggregates to from rod-like structures at high concentrations. We believe that this model reproduces the phase behavior of KOL relevant to drug absorption and that it can be used in whole formulation simulations to accelerate the formulation development.