Study of the formation of micro and nano-droplets containing immiscible solutions

Abstract

There is currently significant interest in the multiple resistance to treatment using drugs (MDR), developed by bacteria and malignant tumors. One of the alternatives to the existing medicines and treatment procedures in fighting MDR is strengthening the effects of cytostatics by improving their delivery methods. Such a method is represented by the generation, transport and use of micro-/nano-droplets which contain medicines. This approach can reduce the medicines consumption by generating micro-droplets which contain drugs incorporated in solvents substances; the micro-/nano-droplets can favour a faster delivery to the targets and a higher drug concentration in them. This paper reports first, results concerning the generation of single micro-droplets containing an inner core (medicine solution in water) and a thin layer of oily liquid covering it. This generation is made one by one and it is, at the moment, not conceived as a method for mass production, or in other words for high population of such droplets. We have generated and measured stratified micro-droplets, each of them containing a solution of Vancomycin in ultrapure water as a core and a surrounding layer of Vitamin A in sunflower oil; the micro-droplets generation was made using a double capillary system. Secondly, micro-/nano-droplets were produced by mixing two immiscible solutions in particular conditions (high rotating speed and/or high pressure difference). For this we have studied the generation of emulsions of Vitamin A diluted in sunflower oil and a solution of Tween 80 surfactant in distilled water. The concentration of surfactant in water was, typically, 4 × 10 −5 M. We have studied the dependence of the droplets dimensions in emulsion on the mixing rotation speed, agitation time and components ratio. The droplets diameters were measured using a light scattering method. It is found that at high enough energy input (high rotation speed, large pressure drop) and relatively small oil/water ratio, droplets diameters smaller than 100 nm were obtained.