Development of analytical methods for functional analysis of intracellular protein using signal-responsive silica or organic nanoparticles.

Because proteins control cellular function, intracellular protein analysis is needed to gain a better understanding of life and disease. However, in situ protein analysis still faces many difficulties because proteins are heterogeneously located within the cell and the types and amount of proteins within the cell are ever changing. Recently, nanotechnology has received increasing attention and multiple protein-containing nanoparticles have been developed. Nanoparticles offer a promising tool for intracellular protein analysis because (1) they can permeate the cellular membrane after modification or changing composition, (2) the stability of various proteins is improved by encapsulation within nanoparticles, and (3) protein release and activity can be controlled. In this review, we discuss the development of analytical methods for intracellular functional protein analysis using signal-responsive silica and organic nanoparticles.