We developed a method for impregnation of bacteria into porous substrates. Cells are impregnated and held in pores by using polyelectrolytes and charge interactions. The carriers developed in that way can be used in biotechnological applications e.g. production of bioactive compounds or using in ecoremediation technologies. Cells are held in pores that means there is less contamination wit biomass in final products. The introduction of cells is based on continuous exchange of pressurised and vacuumised conditions where in the first stage bubbles get expanded, liquid cavitated while bubbles get released. In the second stage small bubbles get dissolved by increasing the pressure. By this approach the air entrapped in porous substrate is released which can be then populated with bacteria.
F.33 Slovenian patent
COBISS.SI-ID: 37774085To produce an effective and stable medicine, a careful selection of physical properties of active pharmaceutical ingredients (API) and excipients is required for each type of dosage forms. The size, distribution and shape of the particles can affect bulk properties, process- ability, product performance, stability and appearance of the final product. It is now generally recognized that poorly water-soluble drugs represent a rate-limiting step in dissolution and subsequent bioavailability. Among a number of techniques, available for the formulation of defined micro- or nanosized particles, electrospraying is rapidly emerging as an innovative technology for electrohydrodynamic atomization of solutions. In the present study, an electrospraying process for preparation of nano- and microparticles, comprising pure excipients polycaprolactone, polyvinylpyrrolidone and lactose, pure active ingredients (ciprofloxacin, clarithromycin, metronidazole), or mixtures of polymer and API, was designed and developed. As evident from the results, solvent evaporation from droplets with narrow size distribution led to particle formation with a defined size, distribution and morphology. Irrespective to the molecular properties, polymer solutions resulted in spherical particles. In contrast, API particle morphology depended mainly on its type: clarithromycin formed wrinkled, round platelets or hallow spheres, while solutions of ciprofloxacin produced spherical particles with homogeneous surfaces. The described morphology was preserved when the API and polymer were present in the ratio of 1 : 1. Further on, the obtained formulation and process parameters were chosen for the design of experiments, where the importance of electrohydrodynamic process parameters on particle properties was evaluated, and the process optimized with regard to the desired particle properties. Electrospraying represents a method that enables high drug-loading efficiency, a control over particle size, and consequently narrow size distribution. These attributes are extremely important for appropriate biodistribution and a predictable therapeutic effect.
D.10 Educational activities
COBISS.SI-ID: 4158833Polyelectrolytes can be very efficiently deposited on charged surfaces. In that respect, according to the theory and molecular cellular morphology the surface of cells should be charged. In that respect, the biggest contribution to the negative charge of the cell surface is based on phosphate groups of the membrane phospholipids. Based on that assumption as well as on the assumption that cells are very similar to the nonliving micron sized particle, it was also demonstrated that polyelectrolytes can be deposited on cell surfaces. However, among all those assumptions two important facts has not been kept in mind: (i) cell surface is not composed only of cell membrane and (ii) cell is alive and it is therefore modifying it surface, is dividing and is responding to the environmental changes. In addition, especially bacterial cells are also very special in these two aspects. They are very metabolically diverse and they are very different in molecular composition and their molecular morphology. Here we demonstrated that this diversity extents also in electrostatic properties. We showed that surface charge is different for different bacterial species, strains as well as at different growth time points. This then affects the deposition of polyelectrolytes. In addition, bacterial cells are also electrostatically as well as mechanically very soft and the protocol for omitting aggregation has been needed to be developed, which enabled us to observe changes in whole population of bacterial cells as well as on the level of separate single cells by using time laps microscopy. As a result the deposition of polyelectrolytes on bacterial cells resulted in bacteria entrapment. However, during bacterial growth and division cells can escape. However, this deposition affects their physiology by increasing time for the first division, increasing protein expression and metabolic rate and can increase size of bacterial cells. By such use of polyelectrolyte deposition it can be controlled growth, it can increase production of bioactive substances and can enable regulation of population and interspecies interaction, which will be also shown by some examples.
B.04 Guest lecture
COBISS.SI-ID: 29586215