Preparation of the phycoerythrin subunit liposome in a photodynamic experiment on liver cancer cells.

AIM: Efforts are underway to establish a preparation method for the phycoerythrin subunit (PE-sub) liposome, and enhance the cellular uptake and photodynamic therapy (PDT) effect on cancer cells. METHODS: A film dispersion method was used to prepare the PE-sub liposome, an orthogonal analysis was conducted to optimize the PE-sub liposome preparation condition and determine the effects of liposomes as carriers on cell uptake in vitro. Under a fluorescence microscope, the cell survival rate of normal liver cell line HL7702 and liver cancer cell line HepG2 was assessed by 3-(4,5-dimethylthiazol-2-yl)- 2,5-diphenyltetrazolium bromide assay. Cell apoptosis was determined with flow cytometry and acridine orange staining after PDT treatment. RESULTS: The optimum preparation conditions of the PE-sub liposome were found: a phosphatidylcholine-to-cholesterin ratio of 1:2, a PE-sub-to-lipid ratio of 1:30, 20 mL buffer volume, 10 min sonication time, and an average encapsulation rate of up to 47.2%. The particle size ranged from 80 to 200 nm, and the average particle diameter was 136 nm. At a concentration of 100 microg/mL, the transfection rate of the PE-sub liposome reached 18% at 2 h and 24% at 4 h, and remained steady at 5-6 h. The half lethal dose of PDT on HepG2 was 75 microg/mL, whereas the cell survival rate of HL7702 reached 80% at the same dosage. The PDT-treated cells showed characteristics of apoptosis. CONCLUSION: The film dispersion method was found to maintain the biological characteristics of the PE-sub. The use of the liposome carrier increased the PE-sub accumulation in the cells and enhanced its PDT effect on HepG2 compared to the PE-sub. HL7702 cell toxicity on had less apparent change after PDT treatment. The PE-sub liposome demonstrated good tumor-targeting characteristics in the in vitro experiment.

[Preparation of phycocyanin subunits liposomes and the photodynamic experiment on cancer cells].

Phycocyanin subunits liposomes (PCS-lip) were prepared and its cellular uptake and photodynamic therapy (PDT) effect on cancer cells were studied. In the experiment, film dispersion method was used to prepare phycocyanin subunits liposomes; particle size and distribution were detected by zetasizer and transmission electric microscope; the effects of liposome as carrier on cell uptake in vitro were evaluated in S180 by using fluorescence microscope; and photodynamic therapy effect was assessed with MTT method. As shown in the results, the particle size mainly ranged from 80 nm to 160 nm, and average encapsulation rate was 42.3%. In the concentration of 100 microg x mL(-1), transfection rate reached (18.5 +/- 0.8)% at 2 h, (23.1 +/- 0.9)% at 4 h, keeping a balance in 5-6 h, and its photodynamic therapy effect in vitro improved with the increasing of concentration of phycocyanin subunits liposomes. In the concentration of 200 micro x mL(-1) cell survival rate of BGC-823 and S180 reached (45 +/- 5.2)% and (36 +/- 5.5)%, respectively, and the cell survival rate differentiation between PCS-PDT group and PCS-lip-PDT group reached 7%-11% (P < 0.05). In this study film dispersion method could keep the biological activity of phycocyanin subunits very well. Phycocyanin subunits liposomes will transfect cells more quickly than phycocyanin subunits in the same concentration, and in the same conditions, phycocyanin subunits liposomes have the better PDT effect on cancer cells as they were incubated with cells for 4 h.