Hemolytic activity and platelet aggregation inhibitory effect of vipoxin's basic sPLA2 subunit.

In the present study we evaluated the effect of secreted phospholipase A2 (sPLA2) (the toxic subunit of the heterodimeric neurotoxin vipoxin, isolated from the Bulgarian long-nosed viper Vipera ammodytes meridionalis) on hemolysis, erythrocyte morphology and platelet aggregation. Hemolytic activity of sPLA2 was examined in the presence of saturated (palmitic) and unsaturated (oleic) fatty acids and it was found that oleic acid increased the hemolytic activity of sPLA2 in a concentration-dependent manner, compared to the effect of palmitic acid and controls. The addition of heparin to red blood cells (RBC) suspension containing sPLA2 or mixture of sPLA2 and the corresponding fatty acid led to an inhibition of hemolytic activity. The effect of sPLA2 on RBC morphology resulted in formation of echinocytes (spherocyte subtype), suggesting that RBC could be the possible targets attacked by sPLA2. Vipoxin sPLA2 inhibited (in a dose-dependent manner) platelet aggregation when arachidonic acid and collagen were used as inducers, while in the case of ADP its inhibitory effect was inappreciable.

Tuning of the surface biological behavior of poly(L-lactide)-based electrospun materials by polyelectrolyte complex formation.

Poly(L-lactide) (PLLA) and poly(L-lactide)/poly(ethylene glycol) (PLLA/PEG) electrospun fibrous materials coated with a polyelectrolyte complex (PEC) were prepared. This was achieved by consecutive deposition of a layer of N-carboxyethylchitosan (CECh) and a layer of a double hydrophilic block copolymer, poly(ethylene oxide)-b-quaternized poly[2-(dimethylamino)ethyl methacrylate] (PEO-b-PDMAEMAQ100), resulting in PEC formation between the two polyelectrolytes on the surface. Noteworthy, to improve the water wettability of the electrospun PLLA fibrous materials, that is, to enable more uniform deposition of the polyelectrolyte partners, water/ethanol mixed solvent was used for preparation of CECh and PEO-b-PDMAEMAQ100 solutions. The formation of PEC-based coating was demonstrated by means of scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The PEC formation allows targeted modification of the biological behavior of the electrospun materials as evidenced by the performed tests in respect to blood cells and pathogenic microorganisms. In contrast to the pristine mats, the novel PEC-coated mats exhibit hemostatic properties and reduce the adhesion of pathogenic microorganisms.

Polylactide stereocomplex-based electrospun materials possessing surface with antibacterial and hemostatic properties.

Novel fibrous materials of stereocomplex between high-molecular-weight poly(d- or l-)lactide (HMPDLA or HMPLLA) and diblock copolymers consisting of poly(l- or d-)lactide and poly(N,N-dimethylamino-2-ethyl methacrylate) blocks, respectively (PLLA-block-PDMAEMA or PDLA-block-PDMAEMA), were prepared by solution electrospinning. Fibers with mean diameters ranging from 1400 to 1700 nm were obtained. The stereocomplex formation was evidenced by differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analyses. Annealing at 100 degrees C for 8 h resulted in the appearance of crystalline peaks at 2theta values of 12, 21, and 24 degrees for PLA stereocomplex. X-ray photoelectron spectroscopy (XPS) analyses revealed the gradient composition of the fibers with a surface enriched in tertiary amino groups from PDMAEMA blocks. The availability of tertiary amino groups imparts hemostatic and antibacterial properties to the stereocomplex fibrous materials, as indicated by the performed tests on blood cells and on pathogenic microorganisms.

Polyelectrolyte complexes based on (quaternized) poly[(2-dimethylamino)ethyl methacrylate]: behavior in contact with blood.

Polyelectrolyte complexes (PECs) between (quaternized) poly[2-(dimethylamino)ethyl methacrylate] (PDMAEMA) and (crosslinked) N-carboxyethylchitosan (CECh) or poly(2-acrylamido-2-methylpropane sodium sulfonate) (PAMPSNa) were prepared and characterized in terms of their stability, equilibrium water content, and surface morphology. The evaluation of the behavior of the studied PECs in contact with blood revealed that the (crosslinked) CECh/(quaternized) PDMAEMA complexes had lost the inherent PDMAEMA cytotoxicity but still preserved haemostatic activity. In contrast, the complex formation between (quaternized) PDMAEMA and PAMPSNa allowed the preparation of materials with improved blood compatibility.