Experimental investigation of regenerated cellulose microdialysis probe sterilization

Sterilization of devices is important in hospitals, operating theaters, and emergency rooms. Microdialysis allows in vivo sampling of small molecules and is used for clinical studies. Microdialysis probes are made of soft, flexible, and porous polymeric membranes. They have been traditionally disinfected using either ethanol (which fails to eliminate all microbes and does not 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 thermomechanical 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. Three methods for sterilization of cellulose‐based microdialysis probes were experimentally studied—autoclave and two chemical solutions Sporox II and MetriCide. The effect of sterilization was characterized using scanning electron microscopy, nitrogen sorption, and diffusion of small molecules. Autoclave caused visible damage, while the Sporox II and MetriCide did not cause visible damage nor affected the diffusion of molecules through the microdialysis membrane.