PubMed Health⌕ Search

Biomedical subjects

G Jayasree

Publications and source records attributed to G Jayasree.

3 recordsLinked to original sources

Polyether urethane urea membrane for an improved hemodialysis.

This paper reviews our current activities of developing polyether urethane urea membranes for hemodialysis application. It is observed that the processing parameters such as precipitation medium, precipitation temperature etc. can influence the porosity of the membrane and subsequently the permeability property. Polyurethane/poly(methyl methacrylate) blended membranes have also shown high permeability. All the membranes are subjected to different sterilization processes and the pore sizes before and after sterilization are determined. The changes in the pore size due to sterilization seems to effect the permeability.

Biocompatible Materials↗

Permeability of PEUU membranes: their modification towards blood compatibility.

An attempt was made to develop haemodialysis membranes using polyether urethane urea synthesised in our laboratory. It was observed that the processing parameters such as precipitation medium, precipitation temperature etc. can influence the porosity of the membrane and subsequently the permeability property. It was also noted that the permeability of the dried membrane was negligible even though it was kept in distilled water overnight before use. The effect of pH on permeability through the membrane was studied by dialysis experiment using mixtures of various components such as urea, creatinine, uric acid, inulin, albumin, NaCl and KCl at various pH. Standard cellulose acetate (CA) membrane was used for comparison. Membranes were also prepared using biomer solution by precipitating in distilled water at room temperature and the monomer, 2-hydroxy ethyl methacrylate (HEMA) was grafted onto it by glow discharge technique. It was found that the permeability was increased by HEMA grafting with some loss of tensile strength and strain. A comparative study of fibrinogen adsorption during dialysis and adsorption by direct exposure of samples to a mixture containing urea, uric acid, creatinine, dextran, fibrinogen and electrolytes like sodium and potassium ions was also done with 125I labelled fibrinogen. Platelet adhesion studies indicated that the number of adhered platelets was less on the HEMA grafted samples which may enhance blood compatibility. Finally, the membranes were subjected to different sterilization processes possible under wet conditions such as glutaraldehyde treatment and autoclaving. The contact angle, permeability, mechanical property and platelet adhesion studies indicated that the sterilization method can affect the performance of the membrane.

Adsorption↗

Introduction of surface functional groups onto biomaterials by glow discharges.

An attempt was made to graft the monomer HEMA to the polymer surface by "Glow discharge" technique. Experiments were carried out for different surfaces varying the exposure times of samples to HEMA and also as a function of glow discharge time. It was found that as the percentage of grafting increases the hydrophilicity also increases. Contact angle measurements were performed on these substrates, which confirmed the hydrophilic nature of the grafted samples compared to the controls. The role of protein adsorption and their effects to modulate the blood polymer interaction is briefly discussed. When a foreign material comes in contact with blood, the initial event is the adsorption of plasma proteins in parallel with the adhesion of platelets to the material. Albuminated surfaces discourage platelet adhesion while fibrinogen enhances the platelet attachment and thrombosis. Hence a decreased ratio of fibrinogen to albumin on a substrate can be correlated as an indication to its improved blood compatibility. Fibrinogen to albumin ratios of the grafted samples showed a reduction, indicating that albumin adsorption is high; which may make the modified surfaces non-thrombogenic.

Acrylates↗