Concentration-Dependent Effect of the Steroid Drug Prednisolone on a Lung Surfactant Monolayer

Carboxymethylcellulose hydrogels crosslinked with keratin nanoparticles for efficient prednisolone delivery

Carboxymethylcellulose (CMC) and keratin nanoparticle (KNP) hydrogels were obtained, characterized, and applied as drug delivery systems (DDSs) for the first time. Lyophilized CMC/KNP mixtures containing 10, 25, and 50 wt% of KNPs were kept at 170 °C for 90 min to crosslink CMC chains through a solid-state reaction with the KNPs. The hydrogels were characterized by infrared spectroscopy, thermal analyses, X-ray diffraction, mechanical measurements, and scanning electron microscopy. The infrared spectra indicated the formation of ester and amide linkages between crosslinked CMC and KNPs. The elastic modulus of the hydrogel containing 10 wt% KNPs was 2-fold higher than that of the hydrogel containing 50 wt% KNPs. The mechanical properties influenced the hydrogel stability and water uptake. The anti-inflammatory prednisolone (PRED) drug was incorporated into the hydrogels, and the release mechanism was investigated. The hydrogels supported PRED release by drug desorption for approximately 360 h. A sustained release mechanism was achieved. The CMC/KNP and CMC/KNP/PRED hydrogels were cytocompatible toward mammalian cells. The CMC/KNP/PRED set imparted the highest cell viability after 7 days of incubation. This study showed a straightforward procedure to create DDSs (chemically crosslinked) based on polysaccharides and proteins for efficient PRED delivery.

The concentration-dependent effect of hydrocortisone on the structure of model lung surfactant monolayer by using an in silico approach

Understanding the adsorption mechanism of corticosteroids in the lung surfactant requires the knowledge of corticosteroid molecular interactions with lung surfactant monolayer (LSM). We employed coarse-grained molecular dynamics simulation to explore the action of hydrocortisone on an LSM comprised of a phospholipid, cholesterol and surfactant protein. The structural and dynamical morphology of the lung surfactant monolayer at different surface tensions were investigated to assess the monolayer compressibility. The simulations were also conducted at the two extreme ends of breathing cycles: exhalation (0 mN m^-1 surface tension) and inhalation (20 mN m^-1 surface tension). The impact of surface tension and hydrocortisone concentration on the monolayer compressibility and stability are significant, resulting the monolayer expansion at higher surface tension. However, at low surface tension, the highly compressed monolayer induces monolayer instability in the presence of the drug due to the accumulation of surfactant protein and drug. The constant area per lipid simulation results demonstrate that the surface pressure-area isotherms show a decrease in area-per-lipid with increased drug concentration. The drug-induced expansion causes considerable instability in the monolayer after a specific drug concentration is attained at inhalation breathing condition, whereas, for exhalation breathing, the monolayer gets more compressed, causing the LSM to collapse. The monolayer collapse occurs for inhalation due to the higher drug concentration, whereas for exhalation due to the accumulation of surfactant proteins and drugs. The findings from this study will aid in enhancing the knowledge of molecular interactions of corticosteroid drugs with lung surfactants to treat respiratory diseases.

Effect of Silica Microparticles on Interactions in Mono- and Multicomponent Membranes

Advancing our understanding of the mechanism of the interaction between inhaled pollutant microparticles and cell membrane components is useful to study the impact of fine particulate matter on human health. In this paper, we focus on the effect of cholesterol (Chol) molecules on the surface properties of a model membrane in the presence of silica microparticles (MPs). Mixed monolayers containing phospholipid-dipalmitoylphosphatidylcholine (DPPC), Chol and silica particle dispersions (MPs; 0.033% w/w, 0.33% w/w and 0.83% w/w) were formed and studied using the Langmuir monolayer technique complemented by Brewster Angle Microscopy (BAM) images. It was shown that Chol caused a condensation of the DPPC monolayer, which influenced the penetration of MPs and their interactions with the model membrane. The relaxation experiments of the lipid–MP monolayer proved that the presence of Chol molecules in the monolayer led to the formation of lipid and MP complexes. Strong interactions between Chol and MPs contributed to the formation of more stable monolayers. The presented results can be useful to better comprehend the interaction between particulate materials and the lipid components of biomembranes.

Effect of 1-alkyl-1-methylpiperidinium bromides on lipids of fungal plasma membrane and lung surfactant

This study aimed to investigate the potential of 1-alkyl-1-methylpiperidinium bromides as fungicides and evaluate their impact on the human respiratory system when spread in the atmosphere. We investigated the behavior of membrane lipids and model membranes in the presence of a series of amphiphilic 1-alkyl-1-methylpiperidinium bromides ([MePipC_n][Br]), differing in the alkyl chain length (n = 4 - 18). The experiments were performed with the Langmuir monolayer technique using 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and ergosterol (ERG)-the main components of lung surfactant and fungal plasma membrane, respectively and their mixtures with phospholipids and sterols. The mixtures were chosen as the representatives of target and non-target organisms. The surface pressure-area isotherms were obtained by compressing monolayers in the presence of [MePipC_n][Br] in the subphase. The results were analyzed in terms of area expansion/contraction and compressibility. The surface activity of the studied organic salts was also studied. In addition, the monolayers were deposited on a solid surface and their topography was investigated using atomic force microscopy. This research implies that the studied compounds may destabilize efficiently the fungal plasma membrane. At the same time we demonstrated the significant impact of 1-alkyl-1-methylpiperidinium bromides on the lung surfactant layer. The interaction between [MePipCn][Br] and model membranes depends on the concentration and alkyl chain length of organic salt. The key role of contact time has been also revealed. The results may be helpful in the reasonable development of new agrochemical products aiming at the treatment of fungal infections in plants. In addition, our study indicates the significance of proper safety management while spreading the fungicides in the environment.