Nanocapsules of biodegradable polymers: preparation and characterization by direct high resolution electron microscopy

In the field of pharmaceutical applications relying on encapsulation of drug by polymer coating, capsules based on biodegradable polymers with mean size of about 500 nm have been obtained by a patented emulsion–diffusion method. The morphology, size and structure of the nanocapsules (NC) control their pharmaceutical properties, especially release of the drug. Here is reported a decisive contribution of transmission electron microscopy (TEM) in revealing the controlled form and size of the NC: mean size values measured by TEM do agree with data obtained by laser granulometry. Moreover, the TEM magnification allows an estimation of the membrane thickness.