My research interests are focused on the fields of biotechnology and bioprocess engineering, in particular in the production and purification of monoclonal antibodies. For my master thesis I developed and adapted a method of membrane derivatization to commercially available ultrafiltration (UF) membranes for the polishing of monoclonal antibodies (mAbs). The polyethersulfone membranes were modified by sulfonation, followed by deposition of polyethyleneimine and cross-linking with butanedioldiglycidylether, with the objective of creating a positively charged membrane. The positive charge was expected to impose the necessary electrostatic repulsion between the membrane pores surface and the positively charged mAbs molecules to prevent them to convectively flow through the membrane pore. The modified membranes were able to separate the antibodies from the complex medium achieving, with only one step, a high purity fraction. During my research grant, further studies were conducted in order to increase final product purity and total process yield. Different molecular weights of polymers, membranes and operational conditions were tested. The optimized operational conditions proved to be efficient in the ultrafiltration of a complex cell supernatant, achieving a highly purified final product. During this work, I was also involved in the production of mAbs using a mammalian cell culture.