Gene therapy offers exciting opportunities for the development of therapies in virtually all areas of medicine. Recent clinical advances are starting to realise this potential although there remain many challenges amongst which delivery is a key issue. Much of Stephen’s research has therefore focused on this challenging area to develop delivery methods compatible with clinical use. In particular, he has developed a family of synthetic gene delivery formulations, or nanoparticles, from conceptual stages through to treatment of disease models in vivo. More recently, he has extended our formulations to the delivery of siRNA and other oligonucleotides as well as imaging contrast agents and radiolabels for real-time imaging of delivery in vivo. He has established a number of collaborations, exploiting the breadth of high quality research groups at UCL, including Departments of Chemistry, Biochemical Engineering, Centre for Respiratory Medicine, and the Centre for Cardiovascular Biology and Medicine. These collaborations have led to highly productive interdisciplinary hypothesis-driven research, involving synthesis of novel reagents, studies to establish the fundamental rules and relationships concerning vector structure and function and correction of animal models of disease. Overall the research areas are non-viral vector development and gene therapy for: 1) gene therapy for cardiovascular diseases (bypass grafts), 2) gene therapy for respiratory diseases (cystic fibrosis), 3) gene therapy for cancer (neuroblastoma), 4) gene therapy for the brain, 5) further vector development.