Conversion of purpurin 18 to chlorin P6 in the presence of silica, liposome and polymeric nanoparticles: A spectroscopic study

• Suitability of SiNP as carrier of purpurin 18 (Pp18) was studied spectroscopically.
• Conversion of Pp18 to chlorin p6 was compared among four different NP systems.
• Hydrolysis rate of Pp18 was found to be lowest in vinyl modified silica NP (SiNP-V).
• Our results suggest that SiNP-V could be used as the carrier for Pp18.

Effect of nanoparticle (NP) environment on the conversion of entrapped photosensitizer purpurin 18 (Pp18) to chlorin p6 (Cp6) was studied spectroscopically. This was investigated by monitoring the time dependent absorption and emission kinetics of the Pp18 entrapped in four different NPs suspended in buffer at physiological pH in the presence and absence of serum up to 24 h. These were organically modified silica NP (SiNP) having vinyl and/or amino propyl groups, poly-lactic-co-glycolic acid (PLGA) NP and liposome. The results of the spectroscopic studies reveal that Pp18 is least converted to Cp6 (i.e., most stable) in the SiNP having vinyl groups whereas its conversion is fastest in PC liposome. In the presence of serum proteins, although the conversion is enhanced, the trend remains similar. Our investigation suggests that SiNP having vinyl functional groups might be a better carrier of Pp18 at physiological pH.

Effect of nanoparticle (NP) environment on the conversion of entrapped purpurin 18 (Pp18) to chlorine p6 (Cp6) was studied spectroscopically and compared among four NP systems: organically modified silica NP (SiNP) having vinyl and/or amino propyl groups, poly-lactic-co-glycolic acid (PLGA) NP and liposome. Our investigation suggests that SiNP having vinyl functional groups might be a better carrier of Pp18 at physiological pH.Figure optionsDownload as PowerPoint slide