Commercial poly(acrylonitrile) (PAN) and cationic-clyeable poly(ethylene terephthalate) (PET) were dyed with a fluoroquinolon-type antibiotic, ciprofloxacin (Cipro), to develop infection resistant biomedical materials. Regular PET fiber was also treated as a comparison purpose. Experimental parameters examined were different dyeing temperatures, times, and pHs. To investigate effect of hydrolysis on Cipro sorption, the fibers were hydrolyzed by 1% NaOH for 1 or 2 h at 85 degrees C and 100 degrees C. Regardless of pH conditions, both PAN fibers (Orlon and Acrilan) sorbed high level of Cipro at 100 degrees C for 3.5 h, but zone of inhibition (ZOI) value reached zero at 4 h of wash time. Contrarily, the presence of additional functional groups in PAN and cationicdyeable PET obtained by hydrolysis not only considerably enhanced sorption of Cipro but also provided much better sustained release, indicated by high ZOI value at 24 h of wash time. (c) 2007 Wiley Periodicals, Inc.