Intraperitoneal non-viral nucleic acid delivery is attractive to target peritoneal metastases. We aim to evaluate the stability and aggregation non-viral gene complexes in the peritoneal fluid, by using Fluorescence Fluctuation Spectroscopy and Single Particle Tracking. Also, we aim to develop a thermosensitive hydrogel formulation for delivery of nucleic acids in the intraperitoneal cavity during a prolonged period of time.