Photosan-II loaded hollow silica nanoparticles: preparation and its effect in killing for QBC939 cells.

Background: Nanoparticles have been explored recently as an efficient means to deliver photosensitizers for photodynamic therapy. However, it is largely unknown if polyhematoporphyrin (C34H38N4NaO5, Photosan-II, PS) or other photosensitizers can be efficiently delivered by hollow silica nanoparticles (HSNP).

Methods: Polyhematoporphyrin (C34H38N4NaO5, Photosan-II, PS) was loaded into hollow silica nanoparticles (HSNP) by one-step wet chemical-based synthetic route. Dynamic light scattering (DLS) and polydispersive index (PDI) were used for measurement of the particles size and size distribution. Transmission electron microscope and scanning electron microscopy were used for the microstructure, morphological and chemical composition analysis. Fourier transform infrared spectrometry spectra and fluorescence emission spectrum were obtained. The photobiological activity of the PS-loaded HSNP was evaluated on human cholangiocarcinoma QBC939 cells. The cellular viability was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Apoptotic and necrotic cells were measured by flow cytometry.

Results: DLS measurements showed that the size of the particles is in the range of 25-90 nm. PDI of the PS-loaded HSNP is 0.121 ± 0.01, indicating that samples have excellent quality with narrow size distribution to monomodal systems. In MTT assay, PS-loaded HSNP and free PS of the same concentration killed about 95.3% ± 2.0% and 55.7% ± 1.9% of QBC939 cells, respectively. The flow cytometry demonstrated that the laser induced cell death with PS-loaded HSNP was much more severe than that of free PS (P<0.05).

Conclusions: Photosan-II-loaded hollow silica nanoparticles not only can quickly deliver Photosan-II into cells but also can reach a more high concentration than free Photosan-II. HSNP is a desirable vehicle and the release system that shows promises for photodynamic therapy use, which not only improve the aqueous solubility, stability and transport efficiency of PS, but also increase its photodynamic efficacy compared to free PS.