THE EFFECT OF ELECTROSTATIC CHARGE INTERACTIONS ON RELEASE RATES OF GENTAMICIN FROM COLLAGEN MATRICES

Purpose. This work studied the effect of changes in the magnitude of electrostatic charge interactions on the release kinetics of gentamicin from collagen matrices. Methods. The charge distribution on collagen was altered by specific charge chemistries to yield net negative charges which exhibited binding interactions with positively charged gentamicin. The adsorption isotherms were measured to characterize binding interactions and release of gentamicin from modified matrices were measured. The release rates were compared to a mathematical model based on an instantaneous desorption coupled with diffusion mechanism. Results. Ninety percent of the gentamicin loaded was released from native collagen matrices in 2.5 days (one-sided slab geometry in-vitro). Succinylated collagen matrices released 70% in 2.5 days and phosphonylated collagen matrices released 50% in 2.5 days. Excellent agreement between model predictions and experiment results were obtained. Conclusions. Modified collagen can be much more effective in antibiotic therapy in sustaining release rates compared to native collagen for charged antibiotics like gentamicin.