Zyta Ziora

Interaction of densely polymer-coated gold nanoparticles with epithelial Caco-2 monolayers.

We synthesized a library of polymer-coated gold nanoparticles (AuNPs) with well-defined sizes (5, 10, and 20 nm) and surface properties, and investigated their efficiency to cross the Caco-2 epithelial barrier and disrupt tight junctions connecting the cellular barrier. The positively charged and hydrophobic polymer-coated AuNPs showed little or no translocation across the model Caco-2 monolayer. Most of these positive and hydrophobic nanoparticles were either bound to the surface or internalized within the cell. The neutral and negatively charged polymer-coated AuNPs with a size of 5 nm showed a significantly higher translocation. All polymer-coated AuNPs induced the translocation of small molecules across the cellular monolayer, suggesting the loosening of the paracellular tight junction joining individual cells. The decrease in the TEER values of the monolayers supported the opening of the tight junctions. These tight junctions fully recovered for most polymer-coated AuNPs 12 h after removal of the nanoparticles. The exception was the cationic polymer-coated AuNPs in which the barrier function only recovered up to 62%. The library of polymer-coated AuNPs showed no apparent signs of hemolysis to erythrocytes at physiological pH. Our investigation has provided insight on the influence of polymer coatings on the epithelial barrier.

Structure–Activity Relationship for the Development of a Self-Adjuvanting Mucosally Active Lipopeptide Vaccine against Streptococcus pyogenes

Infection with group A streptococcus (GAS) can result in a number of diseases, some of which are potentially life-threatening. The oral-nasal mucosa is a primary site of GAS infection, and a mucosally active vaccine candidate could form the basis of an antidisease and transmission-blocking GAS vaccine. In the present study, a peptide from the GAS M protein (J14) representing a B cell epitope was incorporated alongside a universal T cell helper epitope and a Toll-like receptor 2 targeting lipid moiety to form lipopeptide constructs. Through structure activity studies, we identified a vaccine candidate that induces J14-specific mucosal and systemic antibody responses when administered intranasally without additional adjuvants. The systemic antibodies elicited were capable of inhibiting the growth of GAS. In addition, J14-specific mucosal antibodies corresponded with reduced throat colonization after respiratory GAS challenge. These preclinical experiments show that this lipopeptide could form the basis of an optimal needle-free mucosal GAS vaccine.

Lipoamino Acids as Major Components of Absorption Promoters in Drug Delivery

Many biologically active compounds are unsuitable for development as drugs due to their poor bioavailability. For hydrophilic compounds, modifications to increase lipophilicity can increase passive diffusion or increase uptake into the lymphatic system. Alternatively, improved bioavailability of hydrophilic drug candidates may be achieved by formulation with absorption promoters such as surfactants, penetration enhancers, or ion pairing agents. This approach to enhancing bioavailability also has the potential to widen the range of compound categories that can be used as chemical probes to study biological systems in cells and in vivo where membrane permeability would otherwise be a significant limitation. Lipidic amino acids, which combine the structural properties of lipids with those of α-amino acids, represent a relatively unexplored class of agents that can improve drug adsorption. This review discusses the potential of absorption promoters possessing lipoamino acids for improving drug bioavailability.

Thymine, adenine and lipoamino acid based gene delivery systems

A novel class of thymine, adenine and lipoamino acid based non-viral carriers for gene delivery has been developed. Their ability to bind to DNA by hydrogen bonding was confirmed by NMR diffusion, isothermal titration calorimetry and transmission electron microscopy experiments.

Ethanol Concentration Influences the Mechanisms of Wine Tannin Interactions with Poly(L-proline) in Model Wine.

Changes in ethanol concentration influence red wine astringency, and yet the effect of ethanol on wine tannin-salivary protein interactions is not well understood. Isothermal titration calorimetry (ITC) was used to measure the binding strength between the model salivary protein, poly(L-proline) (PLP) and a range of wine tannins (tannin fractions from a 3- and a 7-year old Cabernet Sauvignon wine) across different ethanol concentrations (5, 10, 15, and 40% v/v). Tannin-PLP interactions were stronger at 5% ethanol than at 40% ethanol. The mechanism of interaction changed for most tannin samples across the wine-like ethanol range (10-15%) from a combination of hydrophobic and hydrogen binding at 10% ethanol to only hydrogen binding at 15% ethanol. These results indicate that ethanol concentration can influence the mechanisms of wine tannin-protein interactions and that the previously reported decrease in wine astringency with increasing alcohol may, in part, relate to a decrease tannin-protein interaction strength.

Reactions of N‐phthalylamino acid chlorides with trialkyl phosphites

Reaction of commercially available trialkyl phosphites with N-phthalylamino acids gave mixtures of seven products, whereas the same reaction carried out with pure triethyl phosphite yielded only the desired 2-(N-phthalytamino)-1-oxoalkanephosphonates. These compounds underwent rearrangement to the same types of products that were obtained with the commercial phosphites. This latter series of reactions was promoted by the presence of dialkyl phosphites.

Wound dressings from naturally-occurring polymers: A review on homopolysaccharide-based composites

Wound dressings are designed to support the wound bed and protect it from the factors that may delay or impede its healing such as contaminations and moisture-loss, thereby facilitating and accelerating the healing process. The materials used to prepare wound dressings include natural and synthetic polymers, as well as their combinations, in the forms of films, sponges and hydrogels. Polysaccharides are naturally-occurring polymers that have been extensively used as wound dressing materials. Homopolysaccharides are a class of polysaccharides consist of only one type of monosaccharide. The current review intends to overview the studies in which wound dressings from naturally-occurring polymers, based on homopolysaccharides, were prepared and evaluated. Homopolysaccharides such as cellulose, chitosan, chitin, pullulan, starch and β-glucan were considered.

Short cationic lipopeptides as effective antibacterial agents: Design, physicochemical properties and biological evaluation.

The spread of drug-resistant bacteria has imparted a sense of urgency in the search for new antibiotics. In an effort to develop a new generation of antibacterial agents, we have designed de novo charged lipopeptides inspired by natural antimicrobial peptides. These short lipopeptides are composed of cationic lysine and hydrophobic lipoamino acids that replicate the amphiphilic properties of natural antimicrobial peptides. The resultant lipopeptides were found to self-assemble into nanoparticles. Some were effective against a variety of Gram-positive bacteria, including strains resistant to methicillin, daptomycin and/or vancomycin. The lipopeptides were not toxic to human kidney and liver cell lines and were highly resistant to tryptic degradation. Transmission electron microscopy analysis of bacteria cells treated with lipopeptide showed membrane-damage and lysis with extrusion of cytosolic contents. With such properties in mind, these lipopeptides have the potential to be developed as new antibacterial agents against drug-resistant Gram-positive bacteria.

Group A Streptococcal Vaccine Candidates based on the Conserved Conformational Epitope from M Protein

Copper catalysed azide alkyne Huisgen cycloaddition (click) reaction assisted conjugation of the multiple copy of conserve epitope (J14) derived from Group A Streptococcal M-protein to LCP core induced desired α-helical conformation of the epitope. The constructs were able to self assemble into large nanoparticles under aqueous conditions. Immunological assessment of these particles demonstrated their capacity to elicit high-titer systemic IgG antibodies against the epitope without help of adjuvant. The LCP systems incorporating the epitope via its N- or C-termini did not elicit significantly different immune responses.

Synthesis of glycolipopeptidic building blocks for carbohydrate receptor discovery

A class of glycolipopeptides for use as building blocks for a new type of dynamic combinatorial library is reported. The members of the library consist of a variable carbohydrate moiety, coded amino acids, and lipoamino acids in order to convert them into amphiphiles. Glycolipopeptidic amphiphiles interact through non-covalent bonding when mixed together in aqueous phase and form micelles in dynamic close-packed fluid mosaic arrays. The head groups of amphiphiles are exposed on the micelle surface, providing entities which could be screened in biological assays to find the most potent combination of building blocks in order to identify new bioactive carbohydrate ligands.