Proteins play a crucial role in life, taking part in all vital processes in the body. In the past decade, there was increasing interest in delivering active forms of proteins to specific cells and organs. Intracellular protein delivery holds enormous promise for biological and medical applications, including cancer therapy, vaccination, regenerative medicine, treatment for loss-of-function genetic diseases and imaging. This tutorial review surveys recent developments in intracellular protein delivery using various nanocarriers. Methods such as lipid-mediated colloidal systems, polymeric nanocarriers, inorganic systems and protein-mediated carriers are reviewed. Advantages and limitations of current strategies, as well as future opportunities and challenges are also discussed.

for their able and enthusiastic help in compiling data for this research. Carsten Holz was generous in helping us with conceptual issues and data problems. Sylvie Demurger generously provided her data on infrastructure and the population with schooling at the secondary level and higher. We thank

Atomic compositions and molar extinction coefficients of PbSe semiconductor nanocrystals were determined by atomic absorption spectrometry, UV-vis-NIR spectrophotometry, and transmission electron microscopy. The Pb/Se atomic ratio was found to be size-dependent with a systematic excess of Pb atoms in the PbSe nanocrystal system. Experimental results indicated that the individual PbSe nanocrystal was nonstoichiometric, consisting of a PbSe core and an extra layer of Pb atoms. For these nonstoichiometric PbSe semiconductor nanocrystals, we proposed a new computational approach to calculate the total number of Pb and Se atoms in different sized particles. This calculation played a key role on the accurate determination of the strongly size-dependent extinction coefficient, which followed a power law with an exponent of approximately 2.5.

Proteins play a crucial role in life, taking part in all vital processes in the body. Intracellular protein delivery holds enormous promise for biological and medical applications, including cancer therapy, vaccination, regenerative medicine, treatment for loss-of-function genetic diseases and imaging. Engineering vehicles for escorting therapeutic proteins into specific cells in a controlled release fashion has thus generated considerable interest. The development of such therapeutics to selectively target tumor has also been a major research focus in cancer nanotechnology. A novel strategy using polymeric redox-responsive nanocapsules for intracellular protein delivery is described, in which through in situ interfacial polymerization, the target therapeutic protein is noncovalently encapsulated into a biocompatible polymeric shell interconnected by disulfide-containing crosslinkers. The dissociation of the polymeric shell under reducing conditions and the subsequent release of protein were confirmed using cell-free assays in the presence of glutathione. Several therapeutic proteins with different properties, both cytosolic and nuclear, were successfully delivered using the platform. The nanocapsules were demonstrated to be efficiently internalized into mammalian cells through interactions between charge or targeting ligand, iii and to release the protein in the reducing cytosol in active forms. Using such redoxresponsive nanocapsule as a vehicle, pro-apoptotic protein caspase 3 was delivered to induce apoptosis in a variety of human cancer cell lines, including HeLa, MCF-7 and U-87 MG.Tumor-selective killer apoptin was delivered into different breast cancer cell lines as well, which led to rapid resurrection of apoptosis in breast cancer cell lines and shrinkage of xenograft mice models. Tumor suppressor p53 protein, the most commonly mutated protein, was also delivered selectively into tumor cells for apoptosis induction, through targeted redox-responsive nanocapsules. The delivery methodology is general, effective and nontoxic towards healthy cells. This work facilitate the development of new tools for tumorgenesis and drug resistance studies, as well as expanding current therapeutic target pool to many other tumor suppressor proteins for cancer treatment.iv The Dissertation of Muxun Zhao is approved.