Increased Therapeutic Efficacy of SLN Containing Etofenamate and Ibuprofen in Topical Treatment of Inflammation

Innovative formulations, including solid lipid nanoparticles (SLNs), have been sought to improve skin permeation of non-steroidal anti-inflammatory drugs (NSAIDs). The present study explores the use of SLNs, prepared using a fusion-emulsification method, to increase skin permeation and in vivo activity of two relevant NSAIDs: A liquid molecule (etofenamate) and a solid one (ibuprofen), formulated in a 2% hydroxypropyl methylcellulose gel through the gelation of SLN suspensions. Compritol® 888 ATO and Tween® 80 were used as a solid lipid and a surfactant, respectively. All production steps were up scalable, resulting in SLNs with high encapsulation efficiency (>90%), a mean particle size of <250 nm, a polydispersity index <0.2, and that were stable for 12 months. In vitro permeation, using human skin in Franz diffusion cells, showed increased permeation and similar cell viability in Df and HaCaT cell lines for SLN formulations when compared to commercial formulations of etofenamate (Reumon® Gel 5%) and ibuprofen (Ozonol® 5%). In vivo activity in the rat paw edema inflammation model showed that SLN hydrogels containing lower doses of etofenamate (8.3 times lower) and ibuprofen (16.6 times lower) produced similar effects compared to the commercial formulations, while decreasing edema and inflammatory cell infiltration, and causing no histological changes in the epidermis. These studies demonstrate that encapsulation in SLNs associated to a suitable hydrogel is a promising technological approach to NSAIDs dermal application.

Thermomechanical Formulation of Freezing Point Depression Behavior of Liquid on Solid Surface With Nanostructure

In this study, we investigated the freezing point depression of liquids in nanostructures using a new thermomechanical method. First, we experimentally determined the freezing points of water, cyclohexane, and a certain organic material (Chem.A) in nanoscale structures using DSC measurements. Thereafter, we formulated a new equation by improving the Gibbs–Thomson equation, which is the conventional formula for representing the freezing point depression of a liquid in nanostructures. We introduced a new term in this new equation to represent the increase in the kinetic energy of the liquid molecule as a result of collision between the liquid molecules and nanostructure walls. Subsequently, we evaluated the solid–liquid interface free energy of sublimation materials by fitting the theoretical freezing point derived from the new equation to experimental data. In this study, we succeeded in reproducing the experimental data of freezing point depression using the proposed equation. In particular, the freezing points of cyclohexane and Chem.A in the nanostructure were better fitted by this new equation at 10 nm or more compared with the conventional equation. Our results show that the interaction between the wall of the nanostructure and liquid molecules affects freezing point depression.

Entropy Contribution to the Line Tension: Insights from Polymer Physics, Water String Theory, and the Three-Phase Tension

The notion of three-phase (line) tension remains one of the most disputable notions in surface science. A very broad range of its values has been reported. Experts even do not agree on the sign of line tension. The polymer-chain-like model of three-phase (triple) line enables rough estimation of entropic input into the value of line tension, estimated as Γ e n ≅ k B T d m ≅ 10 − 11 N , where d m is the diameter of the liquid molecule. The introduction of the polymer-chain-like model of the triple line is justified by the “water string” model of the liquid state, predicting strong orientation effects for liquid molecules located near hydrophobic moieties. The estimated value of the entropic input into the line tension is close to experimental findings, reported by various groups, and seems to be relevant for the understanding of elastic properties of biological membranes.

Entropy Contribution to the Line Tension: Insights from Polymer Physics, Water String Theory and the Three-Phase Tension

The notion of the three-phase (line) tension remains one of the most disputable notions in the surface science. A very broad range of its values has been reported. Experts even do not agree on the sign of the line tension. The polymer-chain-like model of the three-phase (triple) line enables the rough estimation of the entropic input into the value of the line tension, estimated as &Gamma;_en&cong;(k_B T)/d_m &cong;〖10〗^(-11) N, where d_m is the diameter of the liquid molecule. The introducing of the polymer-chain-like model of the triple line is justified by the &ldquo;water string&rdquo; model of the liquid state, predicting strong orientation effects for liquid molecules located in the vicinity of hydrophobic moieties. The estimated value of the entropic input into the line tension is close to experimental findings, reported by various groups.

A General Model for Thermal Conductivity and Electric Conductivity of Nanofluids

Nanoparticles in nanofluids are in the form of nanoparticle clusters caused by aggregation. In order to calculate the thermal and electric conductivity of the nanofluids, the growth process and three-dimensional space structure of the nanoparticle cluster in the host fluid is simulated, and then the thermal and electric conductivity of the cluster are calculated with the resistance network method. The thermal and electric conductivity of the nanofluid are calculated based on the simulated thermal and electric conductivity of nanoparticle clusters, the volume fraction of nanoparticle clusters to the nanofluid as well as the liquid molecule adsorption layer of the nanoparticle. The simulation method is validated by experimental data.

A Prediction Method for Thermal Conductivity and Electric Conductivity of Nanofluids Based on Particles Aggregation Theory

Nanoparticles in nanofluids are in the form of nanoparticle clusters caused by aggregation. In order to calculate the thermal and electric conductivities of the nanofluids, the growth process and three-dimensional space structure of the nanoparticle cluster in the host fluid was simulated, and then the thermal and electric conductivities of the cluster were calculated with the resistance network method. The thermal and electric conductivities of the nanofluid were calculated based on the simulated thermal and electric conductivities of nanoparticle clusters, the volume fraction of nanoparticle clusters to the nanofluid as well as the liquid molecule adsorption layer of the nanoparticle. The simulation method was validated by experimental data.