Scanning Probe Nanotomography Research Articles

INVESTIGATION OF NANO- AND MICROSTRUCTURE OF BIOMATERIALS FOR REGENERATIVE MEDICINE BY METHOD OF SCANNING PROBE NANOTOMOGRAPHY

Aim. To perform a study of three-dimensional micro- and nanostructure of porous biocompatible scaffolds and quantitative analysis of nanoscale porosity parameters. Materials and methods . Three-dimensional porous scaffolds made from spidroin rS1/9 (recombinant analog of spider dragline protein) were produced by salt leaching technique. Dimensions of macropores in produced three-imensional scaffolds were in range from 200 to 400 microns. The study of three-dimensional structure of scaffolds was carried out by scanning probe nanotomography technique with the use of experimental setup combining ultramicrotome and scanning probe microscope. Results. Three-dimensional nanotomographical reconstruction of scaffold macropore wall structure is obtained. The formation of three-dimensional network of interconnected pores and channels with characteristic dimensions in range from 20 to 700 nm in the volume of macropore walls of studied scaffolds is observed. Mean pore diameter is 150 nm. Volume porosity of macropore walls is 22% while volume fraction of pores interconnected in large pore clusters is about 20% of all pore volume. Conclusion. Obtained as a result of the study quantitative characteristics of porous micro- and nanostructure of scaffolds show signifi cant degree of nanoscale porosity and percolation of macropore walls what correlates with reported high effi ciency of tissue regeneration on such scaffolds implanted in vivo. Use of scanning probe nanotomography technique for analysis of characteristics and topology of micro- and nanopore systems enables to improve effi ciency of development of novel biocompatible and biodegradable materials with predicted morphological, physical, chemical and biological characteristics.

Combined Scanning Probe Nanotomography and Optical Microspectroscopy: A Correlative Technique for 3D Characterization of Nanomaterials

Combination of 3D structural analysis with optical characterization of the same sample area on the nanoscale is a highly demanded approach in nanophotonics, materials science, and quality control of nanomaterial. We have developed a correlative microscopy technique where the 3D structure of the sample is reconstructed on the nanoscale by means of a "slice-and-view" combination of ultramicrotomy and scanning probe microscopy (scanning probe nanotomography, SPNT), and its optical characteristics are analyzed using microspectroscopy. This approach has been used to determine the direct quantitative relationship of the 3D structural characteristics of nanovolumes of materials with their microscopic optical properties. This technique has been applied to 3D structural and optical characterization of a hybrid material consisting of cholesteric liquid crystals doped with fluorescent quantum dots (QDs) that can be used for photochemical patterning and image recording through the changes in the dissymmetry factor of the circular polarization of QD emission. The differences in the polarization images and fluorescent spectra of this hybrid material have proved to be correlated with the arrangement of the areas of homogeneous distribution and heterogeneous clustering of QDs. The reconstruction of the 3D nanostructure of the liquid crystal matrix in the areas of homogeneous QDs distribution has shown that QDs do not perturb the periodic planar texture of the cholesteric liquid crystal matrix, whereas QD clusters do perturb it. The combined microspectroscopy-nanotomography technique will be important for evaluating the effects of nanoparticles on the structural organization of organic and liquid crystal matrices and biomedical materials, as well as quality control of nanotechnology fabrication processes and products.