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Biomedical subjects

M C Sunny

Publications and source records attributed to M C Sunny.

8 recordsLinked to original sources
PubMed1992

Cross-linked chitosan microspheres: preparation and evaluation as a matrix for the controlled release of pharmaceuticals.

Chitosan microspheres having good spherical geometry and a smooth surface were prepared by the glutaraldehyde cross-linking of an aqueous acetic acid dispersion of chitosan in paraffin oil using dioctyl sulphosuccinate as the stabilizing agent. Microspheres having different degrees of swelling were made by varying the cross-linking density. Microspheres were prepared by incorporating theophylline, aspirin or griseofulvin. Drug incorporation efficiencies exceeding 80% could be achieved for these drugs. In-vitro release studies of these drugs were carried out in simulated gastric and intestinal fluids at 37 degrees C. It was observed that the drug release rates were influenced by the cross-linking density, particle size and initial drug loading in the microspheres.

Aspirin↗
PubMed1992

Effect of fabrication, sterilization and mediators--blood compatibility of polyurethanes.

The possible changes in the surface and physical properties of polyether urethane urea (PEUU) implants, including their interaction with blood, due to the different preparation methods, sterilization techniques and long term storage in different environmental conditions have been investigated by conducting the studies of mechanical properties, contact angle, platelet adhesion and protein adsorption. Considerable variations in the mechanical properties have been observed for the PEUU grafts stored in different conditions. Changes in platelet adhesion and albumin adsorption have also been observed in the case of samples that underwent different sterilization methods. The effect of mediators like bromelain, an enzyme present in pineapple juice, on albumin adsorption and platelet adhesion on PEUU surfaces have been investigated. It seems the presence of pineapple juice increases the adsorption of albumin and reduces the adhesion of platelets on PEUU surfaces.

Biocompatible Materials↗
PubMed1991

Tantalum-loaded polyurethane microspheres for particulate embolization: preparation and properties.

Polyurethane microspheres having diameters in the range 150-1500 microns were prepared by condensation polymerization of toluene diisocyanate (TDI) with poly(tetramethylene glycol) (PTMG) of average mol wt 990 in an aqueous dispersion medium containing dioctyl sulphosuccinate (DOS) as the suspension stabilizer and 1,4-diazabicyclo[2.2.2]octane (DABCO) as the catalyst for polymerization. Incorporation of tantalum powder in the polymerizing phase led to the formation of Ta-loaded microspheres with good radiopacity. Microspheres were surface-modified by grafting methacrylic acid (MA) on to them using gamma-radiation from a Co60 source. Conversion of the grafted MA into its sodium salt imparted hydrophilicity and slipperiness to the microspheres enabling them to pass through Teflon catheters without obstructing the catheter lumen. These microspheres may find application as radiopaque embolization agents.

Biocompatible Materials↗
PubMed1991

Titanium-protein interaction: changes with oxide layer thickness.

Since titanium is being used for various biomedical applications requiring enhanced blood compatibility, which may be partly due to its extremely stable oxide layer, an attempt is made here to understand the effect of oxide layer thickness on protein adsorption. Different thickness of oxide layers have been coated on titanium foil using anodizing method and thickness of oxide layers deposited have been measured by an ellipsometer. Studies of competitive adsorption of proteins, using I125 labelled protein from a mixture of 25 mg% albumin, 15 mg% gamma-globulin and 7.5 mg% fibrinogen indicate an increased adsorption of proteins onto the oxide layer coated surfaces compared to the bare surface.

Adsorption↗
PubMed1991

Surface modification of corneal contact lens with phosphoryl choline by glow discharge.

Polymers like poly(methylmethacrylate) (PMMA) and poly(2-hydroxyethylmethacrylate) (PHEMA) are widely used in the development of hard and soft contact lenses. Cell adhesion and deposition of chemicals such as calcium, lipoproteins and mucin on the lens surface cause visual acuity which is the main problem in extended uses of contact ocular lenses. In order to minimise the cell adhesion and other type of depositions, a method of surface modification of lens involving the use of phosphoryl choline, a phospholipid and the glow discharge technique has been described. The power variation of the lenses after modification has been checked using Topcon lensometer. The possible power changes of the modified samples due to the exposure to the normal light in the laboratory, darkness, ultraviolet (U.V.) light or saline have been investigated by taking the visible and ultra violet spectra using Beckman spectrophotometer. Surface energy variations after modifications of the samples have been checked by sessile drop water contact angle measurements. Glow discharge treatment increases the hydrophilicity of the samples. It seems, the modifications do not affect the power of hard contact lens significantly. It is also observed that the exposure of samples to the normal light in the laboratory, darkness, U.V. light or saline make no significant change in the visible and ultraviolet spectra of the samples before and after modification.

Air↗
PubMed1990

Albumin adsorption on to aluminium oxide and polyurethane surfaces.

The changes in protein adsorption onto aluminium surfaces coated with different thicknesses of oxide layers were examined. The oxide layers on aluminium substrates were derived by the anodizing technique. Protein adsorption studies were conducted using 125I-labelled albumin and the amount of albumin adsorbed was estimated with the help of a gamma counter. An increase in albumin adsorption was observed on oxide layer coated aluminium surfaces. The effect of anti-Hageman factor on albumin and fibrinogen adsorption on to bare aluminium, oxide layer coated aluminium and bare polyether urethane urea surfaces was also investigated. It was observed that the presence of anti-Hageman factor increased the adsorption of albumin and fibrinogen on to all these substrates.

Adsorption↗