Morphology, granulometry and chemical composition in pharmacology - SEM/FIB/EDX

In recent years, a great deal of research effort has gone into the development of micro- and nano-vectors for controlled release and targeted delivery of active substances. The substrates used to release the active ingredient are often similar in composition to polymers, and therefore sensitive to electron beams.

SEM is used to examine the morphology and size of nanoparticles used in pharmaceutical formulations. Its high resolution makes it possible to visualize the structural details of nanoparticles.

The release properties of micro/nanoparticles can vary according to their size, shape, surface structure and chemical composition. SEM enables high-resolution analysis of characteristics such as size, morphology and structure of microspheres, helping to optimize their ability to release active ingredients and drug design.

SEM gives access to the number distribution of nanoparticles, key data for defining a nanomaterial.

The French National Institute for Research and Safety (INRS) distinguishes between nanoparticles and nanomaterials. A nanoparticle is a particle with three dimensions between 1 and 100 nm. The INRS defines nanomaterials as "a material with at least one external dimension on the nanometric scale, i.e. between 1 and 100 nm, or with an internal or surface structure on the nanometric scale" (definition found in ISO TS 80004-1). The European Commission, for its part, considers a threshold concentration of 50% nanoparticles to define a nanomaterial. For almost ten years, TESCAN ANALYTICS has been a member of the nanoparticle working groups led by LNE. In 2022, the Nanomesure France association, to which TESCAN ANALYTICS belongs, was created with the aim of structuring the nanoparticle industry.

SEM is a technique capable of producing high-resolution images of the surface of a sample. It is used in many fields, from biology to materials science and microelectronics, and on all types of sample. Even insulating materials can be observed after metallization, in a controlled inert atmosphere or at low voltages (close to kV).

SEM is generally used to study the 3D morphology of a surface or object with nanometric resolution. Elemental chemical composition can also be obtained by X-ray microanalysis.

The principle of this technique is based on the use of an incident electron beam of a few tens of kilovolts scanning the surface of the sample, which then re-emits a whole spectrum of particles and radiation: secondary electrons, backscattered electrons, Auger electrons and X-rays. Detection of the various particles or radiation emitted provides information about the sample: its morphology, topography, crystalline structure, elemental chemical composition (qualitative and semi-quantitative analysis)...

TESCAN ANALYTICS has over 30 years' expertise in the use of SEM/FIB/EDX on all types of materials, whether insulating or conductive... With state-of-the-art instruments, our team of experts works with all industrial sectors.

 

Figure 2 : High-resolution SEM image of drug-releasing PLGA microparticles: large-scale observation (2 x 2 µm2)

Figure 3 : SEM image of an active ingredient in powder form (5 x 5 µm2)
 

Figure 4 : SEM image of polymer microvectors for sustained drug release (600 x 600 µm2)

In these non-exhaustive examples, it has been demonstrated that scanning electron microscopy (SEM), with or without FIB and EDX, is an ultra-powerful microscopy tool for studying the structure, size distribution and chemistry of micro-nanovectors used in pharmacology.

With an excellent depth of field (~ 100 x that of optical microscopy), the SEM provides high-resolution images of all materials.

For more applications of SEM analysis or our other analytical techniques and microscopy, click here.

The combination of SEM/EDX and ToF-SIMS techniques facilitates comprehensive analysis of the elemental and molecular composition of materials. AFM gives access to the 3D morphology and surface mechanical properties of nanoparticles. X-ray tomography enables non-destructive visualization of internal features such as porosity, cracks and phase distribution. In dynamic mode, it is possible to visualize "in situ" 3D changes in the internal structures of a material when it undergoes modifications such as mechanical deformation, temperature changes or absorption of liquids.