Archaebacterial tetraetherlipid liposomes

Highly Stable Liposomes Based on Tetraether Lipids as a Promising and Versatile Drug Delivery System

Conventional liposomes often lack stability, limiting their applicability and usage apart from intravenous routes. Nevertheless, their advantages in drug encapsulation and physicochemical properties might be helpful in oral and pulmonary drug delivery. This study investigated the feasibility and stability of liposomes containing tetraether lipids (TEL) from Thermoplasma acidophilum. Liposomes composed of different molar ratios of TEL:Phospholipon 100H (Ph) were produced and exposed to various temperature and pH conditions. The effects on size, polydispersity index, and zeta potential were examined by dynamic and electrophoretic light scattering. Autoclaving, which was considered an additional process step after fabrication, could minimize contamination and prolong shelf life, and the stability after autoclaving was tested. Moreover, 5(6)-carboxyfluorescein leakage was measured after incubation in the presence of fetal calf serum (FCS) and lung surfactant (Alveofact). The incorporation of TEL into the liposomes significantly impacted the stability against low pH, higher temperatures, and even sterilization by autoclaving. The stability of liposomes containing TEL was confirmed by atomic force microscopy as images revealed similar sizes and morphology before and after incubation with FCS. It could be concluded that increasing the molar ratio in the TEL:Ph liposome formulations improved the structural stability against high temperature, low pH, sterilization via autoclaving, and the presence of FCS and lung surfactant.

First Isolation and Structure Elucidation of GDNT-β-Glu - Tetraether Lipid Fragment from Archaeal Sulfolobus Strains

Due to their special chemical structure, tetraether lipids (TEL) represent essential elements of archaeal membranes, providing these organisms with extraordinary properties. Here we describe the characterization of a newly isolated structural element of the main lipids. The TEL fragment GDNT-β-Glu was isolated from Sulfolobus metallicus and characterized in terms of its chemical structure by NMR- and MS-investigations. The obtained data are dissimilar to analogically derived established structures - in essence, the binding relationships in the polar head group are re-determined and verified. With this work, we provide an important contribution to the structure elucidation of intact TEL also contained in other Sulfolobus strains such as Solfulobus acidocaldarius and Sulfolobus solfataricus.

Antibacterial and anti-encrustation biodegradable polymer coating for urinary catheter

Bacterial biofilm and crystalline deposits are the common causes of failure of long-term indwelling urinary catheter. Bacteria colonise the catheter surface causing serious infections in the urinary tract and encrustations that can block the catheter and induce trauma in patients. In this study, the strategy used to resist bacterial adhesion and encrustation represents a combination of the antibacterial effects of norfloxacin and silver nanoparticles and the PLGA-based neutralisation of alkali products of urea hydrolysis gained through the degradation of the polymer in an aqueous milieu. Silver nanoparticles were coated with tetraether lipids (TEL) to avoid aggregation when dispersed in acetone and during the film formation. The polymer films loaded with the two antibacterial agents were applied on Polyurethane (PUR) and Silicon sheets. We demonstrated the antibacterial and anti-adhesion effectiveness of the coatings whereby commercially available biocompatible polymers PUR and Silicon were used as controls. Using artificial urine and an in vitro encrustation model, it was shown that the coatings resist the encrustation for at least 2 weeks. This combination of a biodegradable polymer and wide-range antibacterial agents represents a potentially attractive biocompatible coating for urinary catheters.