Antitumor vector systems based on bioactive lectin of Bacillus subtilis ІМВ B-7724

Abstract

Сombination of properties of lectins and magnetically sensitive iron-containing nanocomposites (NC) for use in oncology is actual and promising from scientific and applied point of view. The aim of the research is to synthesize and to study new iron-containing NC and magnetic fluids containing bioactive bacterial lectin, promising for use as prototypes of new effective antitumor vector systems for targeted drug delivery and combined local therapy of cancer with minimized side effects on the body and improved compatibility with other remedies. To create vector systems, nanodisperse magnetite was synthesized by the Elmore reaction. The synthesis of aluminum-containing coating on the surface of Fe3O4 was carried out by double chemical modification with aluminum isopropylate. The obtained Fe3O4/Al2O3 NC was impregnated with sucrose solutions. Carbonization of the carbohydrate shell of NC was carried out in argon (500 °C). As a result, Fe3O4/Al2O3/C NC was obtained. The magnetic properties of nanostructures were measured using a laboratory vibration magnetometer of Foner type at room temperature. Adsorption immobilization of lectin was performed in 0.9 % NaCl solution in a dynamic mode at room temperature. Bacterial cytotoxic lectin of B. subtilis IMB B-7724 was used in the experiments. The amount of adsorbed substance (A) on the surface of nanocomposites was determined by measuring the concentration of lectin in the contact solutions before and after adsorption using a calibration graph. Measuring of the optical density and absorption spectra of lectin was performed on a spectrometer Lambda 35 UV/vis Perkin Elmer Instruments at λ = 280 nm. Standard techniques and equipment were used for biological research. The processes of adsorption immobilization of cytotoxic bacterial lectin of B. subtilis IMB B-7724 from physiologic saline on the surface of magnetite and carbon-containing Fe3O4/Al2O3/C NC were studied at room temperature. It has been found that the adsorption capacity of lectin on the surface of magnetite is 25.3 mg/g, and Fe3O4/Al2O3/C NC – 36.3 mg/g (at initial concentrations of lectin 0.06–0.4 mg/mL). The extraction extent of lectin R (%) was 12–38 % for magnetite and 46–67 % for Fe3O4/Al2O3/C NC. The dependence of the adsorption capacity on time was studied. A magnetic fluid (MF) based on single-domain Fe3O4, containing lectin was synthesized and investigated. Immobilization of lectin on MF particles was carried out in a dynamic mode at room temperature for 3 hours. The concentration of lectin in the composition of MF was 0.2 mg/mL. MF with immobilized lectin was further modified with PEG-2000. The synthesis of Fe3O4/ol.Na/lectin/PEG (ol.Na – sodium oleate) vector system was carried out in a dynamic mode for 3 hours. Modification of the surface of nanoparticles with polyethylene glycol was performed in order to increase the stability of the magnetic fluid, reducing the aggregation of particles. To determine the effect of experimental samples on the viability of MCF-7 cells in vitro, the following samples were prepared: Fe3O4/ol.Na/PEG (MF), CFe3O4 = 3 mg/mL; cytotoxic lectin of B. subtilis IMB B-7724 (CL), CCL = 0.2 mg/mL; nanobiocomposite (NBC). Nanobiocomposite based on MF and bacterial lectin was found to have a synergistic cytotoxic effect on MCF-7 human breast cancer cells, causing up to 40 % cell death. The IC50 values for the nanobiocomposite and lectin in relation to MCF-7 cells were 100 and 125 μg/mL, respectively. The results of research show that the combination of properties of lectins and magnetically sensitive iron-containing NC for use in oncology is a promising direction in creating new effective antitumor vector systems for targeted drug delivery and combined local therapy of cancer. The use of natural components in vector systems is a way to minimize the side effects on the body and improve compatibility with other antitumor remedies.