Experimental Investigation of Regenerated Cellulose Microdialysis Probe Sterilization

Sterilization of devices is important in hospitals, operating theatres, and emergency rooms. Microdialysis allows in vivo sampling of small molecules and is used for clinical studies. Microdialysis probes are made of soft, flexible, porous polymeric membranes. They have been traditionally disinfected using either ethanol (which fails to eliminate all microbes and doesn't satisfy regulatory requirements) or ethylene oxide gas and gamma irradiation (that are expensive and resource-intensive). In this work, three methods for microdialysis probe-sterilization were studied - autoclave and two chemicals (commercially available sterilization solutions): Sporox II and MetriCide. Following sterilization, the regenerated cellulose membranes were characterized under scanning electron microscopy and by measuring the changes in pore characteristics using nitrogen sorption. To determine the effect of sterilization on analyte diffusion through the membrane, microdialysis probes were fabricated, sterilized and tested with two analytes; ethanol and dopamine. The autoclaved membranes suffered thermo-mechanical damage and were deemed unfit for further testing. Probes sterilized with the chemical solutions were subsequently characterized by in vitro microdialysis experiments performed under regulated mass flux conditions. It is concluded that autoclaving is not a suitable sterilization technique for the cellulose membranes, while both of the chemical sterilizers were found to be good candidates for sterilization.