Production of singlet oxygen by Ru(dpp(SO3)2)3 incorporated in polyacrylamide PEBBLES

Polyacrylamide (PAA) and amine-functionalized PAA (AFPAA) nanoparticles with disulfonated 4,7-diphenyl-1,10-phenantroline ruthenium (Ru(dpp(SO3)(2))(3)) have been prepared. The nanoparticles produced have a hydrodynamic radius of 20-25 nm. The amount of singlet oxygen (O-1(2)) produced by Ru(dpp(SO3)(2))(3) as been measured using anthracene-9,10-dipropionic acid (ADPA). A kinetic model for the disappearance of ADPA, by steady state irradiation of Ru(dpp(SO3)(2))(3) at 465 nm, has been developed taking also into account a consumption not mediated by O-1(2). This direct consumption of ADPA is evaluated by irradiating in the presence of NaN3 and is about 30% of the total. All the experimental results are very well described by the model developed, both for free Ru(dpp(SO3)(2))(3) and with this dye incorporated in the nanoparticles. It is found that the polyacrylamide matrix does not quench the O-1(2) produced, allowing it to reach the external solution of the nanoparticles and react with ADPA. When the matrix possesses amine groups, AFPAA, the amount of O-1(2) that reacts with ADPA is slightly reduced, 60%, but most of the O-1(2) produced can still leave the particles and react with external molecules. The particles produced may therefore be used as sources of O-1(2) in photodynamic therapy (PTD) of cancers. The fact that those nanoparticles do not quench significantly the O-1(2) makes possible the future development of O-1(2)) sensors based on PAA nanoparticles with the appropriate sensor molecule enclosed. (C) 2003 Elsevier Science B.V. All rights reserved.