Charge reversal self-emulsifying drug delivery systems: A comparative study among various phosphorylated surfactants.

Hypothesis: Phosphorylated surfactants having ethoxylate spacer arms are promising excipients for charge reversal self-emulsifying drug delivery systems (SEDDS).

Experiments: 1,2-Dipalmitoyl-sn-glycero-3-phosphatidic acid disodium salt (PA), 2-((2,3-bis(oleoyloxy)propyl)dimethylammonio)ethyl hydrogen phosphate (DOCP), nonylphenol monophosphate ester (PNPP), C12-15 alcohol 3 ethoxylate phosphate ester (PME) and polyoxyethylene (9) dioctanoyl glycerol pyrophosphate (DGPP) loaded SEDDS were developed and characterized. Zeta potential of SEDDS was measured before and after incubation with intestinal alkaline phosphatase (IAP).

Lysine-Based Biodegradable Surfactants: Increasing the Lipophilicity of Insulin by Hydrophobic Ion Paring.

Aim: The aim of this study was to evaluate biodegradable cationic surfactants based on lysine.

Methods: Lysine was esterified with cholesterol, oleyl alcohol and 1-decanol resulting in cholesteryl lysinate (CL), oleyl lysinate (OL) and decyl lysinate (DL). Esters were investigated regarding their log D, critical micelle concentration (CMC) and biodegradability.

Thiolated Chitosans: A Multi-talented Class of Polymers for Various Applications.

Various properties of chitosan can be customized by thiolation for very specific needs in a wide range of application areas. Since the discovery of thiolated chitosans, many studies have proven their advantageous characteristics, such as adhesion to biological surfaces, adjustable cross-linking and swelling behavior, controllable drug release, permeation as well as cellular uptake enhancement, inhibition of efflux pumps and enzymes, complexation of metal ions, antioxidative properties, and radical scavenging activity. Simultaneously, these polymers remain biodegradable without increased toxicity.

Less Reactive Thiol Ligands: Key towards Highly Mucoadhesive Drug Delivery Systems.

As less reactive s-protected thiomers can likely interpenetrate the mucus gel layer to a higher extent before getting immobilized via disulfide bond formation with mucins, it was the aim of this study to develop a novel type of s-protected thiomer based on the less reactive substructure cysteine--acetyl cysteine (Cys-NAC) in order to obtain improved mucoadhesive properties. For this purpose, two types of s-protected thiomers, polyacrylic acid-cysteine-mercaptonicotinic acid (PAA-Cys-MNA) and polyacrylic acid-cysteine--acetyl cysteine (PAA-Cys-NAC), were synthesized and characterized by Fourier-transform infrared spectroscopy (FT-IR) and the quantification of attached disulfide ligands. The viscosity of both products was measured in the presence of NAC and mucus.

Phosphorylated PEG-emulsifier: Powerful tool for development of zeta potential changing self-emulsifying drug delivery systems (SEDDS).

Aim: It was the aim of this study to synthesize a phosphorylated emulsifier possessing a PEG-linker for establishment of a potent zeta potential changing system in self-emulsifying drug delivery systems (SEDDS).

Methods: N,N'-Bis(polyoxyethylene)oleylamine (POA) was phosphorylated utilizing pyrophosphoric acid. Successful synthesis of POA bisphosphate (POAP) was confirmed by NMR and HR CS MAS.

Characterization of an amino acid based biodegradable surfactant facilitating the incorporation of DNA into lipophilic delivery systems.

Hypothesis: Lysine based cationic surfactants are well-tolerated tools for hydrophobic ion pairing (HIP) with DNA and its incorporation into lipophilic delivery systems.

Experiments: Di-Boc-lysine was esterified with 1-hexadecanol and the Boc-residues were cleaved off resulting in hexadecyl lysinate (HL). Subsequently, its Log P and the critical micelle concentration (CMC) were determined.

Arginine-based cationic surfactants: Biodegradable auxiliary agents for the formation of hydrophobic ion pairs with hydrophilic macromolecular drugs.

Working Hypothesis: It was the hypothesis of this study that esters of arginine (Arg) with medium and long chain aliphatic alcohols are biodegradable and less cytotoxic than well-established cationic surfactants being used for hydrophobic ion pairing (HIP) with hydrophilic macromolecular drugs.

Experiments: Arg was linked to nonan-1-ol and hexadecan-1-ol (C and C) via an ester linkage. The newly formed Arg-nonyl ester (ANE) and Arg-hexadecanoyl ester (AHE) surfactants were evaluated regarding critical micelle concentration (CMC) using pyrene fluorescent method, cytotoxicity on human colorectal adenocarcinoma-derived cells (Caco-2) and biodegradability at the concentrations of 2.