A novel chloramphenicol (CAP) biosensor composed of antibody immobilization on electrospun polystyrene (PS) membranes and quartz crystal microbalance (QCM) was successfully fabricated. The three-dimensional fibrous PS membranes comprising the porous PS fibers were deposited on the electrode of QCM via electrospinning, followed by the functionalization of the sensing antibody on the membranes. The functionality of the immobilized antibodies with the 3-mercaptopropionic acid (MPA) method was tested with CAP. The frequency decrease was compared with the results of a similar system activated with polyethyleneimine-glutaraldehyde immobilization. The MPA method showed the best results in terms of sensitivity. The antibody-functionalized MPA biosensor sensitivity increased concurrently with increasing the PS loading and the specific surface area on the QCM. The biosensor responses showed good linearity in the 5-100 ppb concentration range. The resultant biosensors showed fast response (2-3 s) to CAP, with a detection limit of 5 ppb with optimal structure and activation time. Moreover, the biosensors also exhibited good capturing selectivity to CAP when tested with other antibiotics at a concentration between 5 and 200 ppb. (C) 2011 Elsevier B.V. All rights reserved.