1. Department of Pharmaceutics, School of Pharmacy, Fudan University, P.O. Box 130, 138 Yixueyuan Road, Shanghai 200032, P.R. China, Department of Pharmacology, Institute of Medical Sciences, Shanghai Jiaotong University School of Medicine, 280 South Chongqing Road, Shanghai 200025, P.R. China, and Surface Physics Laboratory (National Key Laboratory), Physics Department, Fudan University, Shanghai 200433, P.R. China