To investigate the effect of hydrophobicity, charge and size of photosensitizers (PS) on their encapsulation efficiency in organically modified silica nanoparticles (ORMOSIL), a series of alkyl ether analogs of 2-(1′-hexyloxyethyl)-2-devinyl pyropheophorbide-a (HPPH) containing varied number of carbon units, HPPH with anionic and cationic functionalities, and HPPH analogs with molecular weight ranging from ~630 to 6000 Daltons were synthesized. Our preliminary results suggest that these factors play a significant role in encapsulation of the photosensitizers and their release from ORMOSIL nanoparticles. The synthesis and characterization of PS-encapsulated ORMOSIL and a comparative study on the effect of PS size, lipophilicity and charge on encapsulation efficiency, photophysical characteristics and release kinetics are discussed.