Encapsulation of zinc phthalocyanine into bovine serum albumin aggregates

Albumin microbubbles conjugated with zinc and aluminum phthalocyanine dyes for enhanced photodynamic activity

Gas-liquid interfaces are reaching a particular interest in biomedicine. Microbubbles, ultrasound contrast agents of clinical routine, gained increasing attention as theranostic platforms due to the preserved acoustic response, drug conjugation capabilities, and applicability in biological barrier opening. A combination of microbubbles and photodynamic therapy agents can enhance the photodynamic effect, yet the evaluation of agent conjugation on microbubble stabilization and photodynamic effect is needed. Hence, two commercially available phthalocyanine photosensitizers - Holosens® (ZnPc) and Photosens® (AlPc) - were coupled with bovine serum albumin before microbubble synthesis. We demonstrated an albumin: phthalocyanine ratio of 1:1 and covalent attachment for ZnPc, a ratio of 1:3 with electrostatic binding for AlPc. Submicron-sized microbubbles (air- and SF6- filled) had a diameter of 0.8 µm. Albumin-phthalocyanine conjugates increased the microbubble concentration and shelf-life stability compared to plain ones. We hypothesized that phthalocyanine fluorescence lifetime values decreased after conjugation with microbubbles due to narrow distance between conjugates in the shell. Agents based on AlPc demonstrated higher photodynamic activity than agents based on ZnPc, and microbubbles preserved acoustic stability in human blood plasma. The biodistribution of AlPc-conjugated microbubbles was evaluated. We conclude that our microbubble platforms demonstrate greater photodynamic activity and prolonged stability for further applications in photodynamic therapy.

Alteration of iron (Fe), copper (Cu), zinc (Zn), and manganese (Mn) tissue levels and speciation in rats with desferioxamine-induced iron deficiency

The objective of the present study was to investigate the impact of iron deficiency and iron replenishment on serum iron (Fe), copper (Cu), manganese (Mn), and zinc (Zn) speciation and tissue accumulation in a deferrioxamine-induced model of iron deficiency. A total of 26 male Wistar rats were divided into three groups: control; Fe-deficient; Fe-replenished (with iron (II) gluconate). Serum ferritin and transferrin levels were assessed using immunoturbudimetric method. Liver, spleen, and serum metal levels were assessed using ICP-MS. Speciation analysis was performed using a hyphenated HPLC-ICP-MS technique. Desferrioxamine injections resulted in a significant decrease in tissue iron content that was reversed by Fe supplementation. Iron speciation revealed a significant increase in serum transferrin-bound iron and reduced ferritin-bound Fe levels. Serum but not tissue Cu levels were characterized by a significant decrease in hypoferremic rats, whereas ceruloplasmin-bound fraction tended to increase. At the same time, Zn levels were found to be higher in liver, spleen, and serum of Fe-deficient rats with a predominant increase in low molecular weight fraction.Both iron-deficient and iron-replenished rats were characteirzed by increased transferrin-bound Mn levels and reduced low-molecular weight fraction. Hypothetically, these differences may be associated with impaired Fe metabolism under Fe-deficient conditions predisposing to impairment of essential metal handling. However, further studies aimed at assessment of the impact on Fe deficiency on metal metabolism are highly required.

In vitro phototoxicity of zinc phthalocyanine (ZnPc) loaded in liposomes against human breast cancer cells

In this study, zinc phthalocyanine (ZnPc) was encapsulated in liposomes (Phosphatidylcholine (PC) from soybean lecithin (95% phosphatidylcholine, 5% lysophosphatidylcholine), and phosphatidic acid) obtained by a reverse-phase evaporation method. Liposomes were characterized and cytotoxicity and phototoxicity assays were performed using mouse embryo fibroblast (NIH3T3) and human breast cancer (MDAMB231), respectively. ZnPc was successfully encapsulated in liposomes ([Formula: see text]80%), presenting single populations with sizes of [Formula: see text]300 nm and negative zeta potential (-35 to -40 mV). The release profile at different pH presented a biphasic release controlled by the Fickian diffusion mechanism. The cytotoxicity assays carried out on NIH3T3 cells showed that the liposomes provided good protection for ZnPc, and did not affect the viability of non-cancerous cells. In contrast, free ZnPc significantly reduced non-cancerous cell viability at higher concentrations. ZnPc loaded in liposomes ensured a higher phototoxic effect on the MDAMB231 cells at all concentrations tested when exposed to low light dose.