Structural, topographical, and mechanical characteristics of purified polyhydroxyoctanoate polymer

Abstract

Insight into the topographic and mechanical properties of biomaterials allows for efficient selection of a material for a specific application. Here, atomic force microscopy (AFM) and force spectroscopy were exploited to reveal the topographic and mechanical characteristics of charcoal‐purified, solvent‐cast polyhydroxyoctanoate (PHO) film. The root mean square surface roughness of a PHO surface derived from ethyl acetate, acetone, or chloroform solution was 13.2, 11.5, or 30.9 nm, respectively, for 100 μm2 AFM images. The distribution of the local Young's modulus had a maximum of 25.4, 14.1, and 12.6 MPa for PHO films obtained from ethyl acetate, acetone, and chloroform solution, respectively. The positron annihilation spectroscopy measurements allowed us to determine the free volume in the polymer film structure (9.38%). Moreover, a number of additional techniques (X‐ray diffraction, thermogravimetric analysis, differential scanning calorimetry, gel permeation chromatography, NMR, infrared spectroscopy, and polarized light microscopy) were used to reveal PHO features. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47192.

Cellular architecture and migration behavior of fibroblast cells on polyhydroxyoctanoate (PHO): A natural polymer of bacterial origin

“…Nanoindentation values of Young's modulus for PHO are consistent with results provided by literature in previous reports (Table ) . The obtained results indicate that the solvent from which polymer is cast has no significant effect on the final value of both the Young's modulus and the hardness, but it is clearly visible that the biopolymer needs sufficient time after preliminary drying to achieve its final mechanical properties.…”

“…A multilayered study of a PHO polymer was carried out and its properties were compared with glass. Investigations of mechanical properties of the polymer were achieved with nanoindentation method and the results were consistent with these obtained with AFM technique as well as with values obtained with global mechanistic measurements present in earlier reports . Young's modulus values combined with material hardness obtained in our study indicate that PHO can map the mechanical properties of popular petroleum based polymers such as polyethylene (PE) or polystyrene (PS) and allows PHO applications in areas where use of composite materials was required so far.…”

“…It is well known that polymers in the PHA family are completely biocompatible but extraction and preparation methods can lead to impurities (i.e., endotoxins = lipopolysaccharide [LPS]) that may be harmful to living organisms after implantation. Therefore, protocols of PHO extraction with ethyl acetate and further purification on activated charcoal were followed and the cytotoxic impact of biopolymer films on mammalian cells was assessed.…”

“…Polymer was produced as described in our previous work . Hardness and elasticity determination of PHO samples were held on a round microscopic slides covered with a thick (300‐500 μm) layer of polymer.…”

“…Due to its elastomeric properties it can also be a suitable material for external biomedical applications such as wound patches. Recently we have thoroughly characterized PHO films cast from different organic solvents, where a variety of physicochemical methods revealing its structural and surface properties suggesting PHO's high potency in manufacturing of materials for cell attachment have been applied . However still, little is known about cellular behavior on its surface from morphological and mechanistic points of view.…”