Abstract We have obtained kefir biofilms loaded with Maytenus rigida extract. The main goal was to evaluate the influence of the addition of the extract on the biofilms microtexture using stereometric and fractal parameters. Atomic force microscopy, Fourier transform infrared spectroscopy, and contact angle tecniques were used to evaluate the topography, chemical interation and wettability of the biofilms. Chemical evaluation showed that the extract interacts with the polymeric matrix of the biofilms, changing their structure. This behavior affected the surface energy because the wettability decreased when the Maytenus content increased. The surface morphology was also affected and suggested the prevalence of bacteria and yeast at lower and higher extract concentrations, respectively. The surface roughness increased according to the increase in the extract concentration. Texture parameters revealed that the biofilm with lowest concentration had deeper furrows than for higher concentration. Advanced fractal parameters revealed that topographic uniformity, percolation and texture homogeneity were more suitable for the biofilm with 0.25 g.L-1 of extract. These results indicate that this biofilm have promising 3D micromorphology for regenerative medicine application. Furthermore, the physics tools used revealed to be very useful for characterizing of the microtexture of polymeric-based biological materials.

Abstract Kefir is a natural probiotic produced by kefir grains fermentation. Biofilms produced from fresh kefir grains in natura were studied for presenting structural characteristics that will be of great interest in the area of regenerative medicine. This work presents a study on the surface of kefir biofilms, obtained by the cultivation of kefir grains in commercial white sugar. Four different films were produced, varying the concentration of sugar. The crystallinity of the biofilms was analyzed and revealed that sugar concentration influences biofilm amorphousness. Morphology showed that the biofilms presented excellent superficial adhesiveness. Fractal parameters were studied and revealed that there was homogeneity in the biofilm microtexture. Both fractal succolarity and surface entropy showed that the degree of water penetration and topographic homogeneity of the biofilms was not influenced by sugar concentration. These results show that kefir biofilms have excellent structural and morphological properties to be used in the biomedical field.

The use of chitosan biofilm in biomedical fields has a vast therapeutic potential due to useful properties such as biodegradability and antimicrobial activity, however, to achieve successful application some physicochemical properties need to be improved. In this context, the addition of glycerol to this biofilm is an alternative to improve its wettability and flexibility. Thus, low and high concentrations of plasticizer were added to this biomaterial for later characterization regarding its wettability, microstructure, mechanical and chemical properties. Glycerol addition to chitosan resulted in biofilms with more homogeneous surfaces, increased wettability, and increased flexibility, without significant changes in its chemical structure.