- AFM-IR is used to determine the crystallinity degrees of PHB in various environments
- Using nanoscale IR spectroscopy, it was determined that PHB crystallized extremely well when exposed to chloroform
AFM-IR | Chemical Map | Degree of Crystallinity | Bacterial poly(hydroxybutyrate) | Nanoscale Infrared Spectrsoscopy
R. Rebois, D. Onidas, C. Marcott, I. Noda, A. Dazzi
Poly[(R)-3-hydroxyalkanoate]s or PHAs are aliphatic polyesters produced by numerous microorganisms. They are accumulated as energy and carbon reserve in the form of small intracellular vesicles. Poly[(R)-3-hydroxybutyrate] (PHB) is the most ubiquitous and simplest PHA. An atomic force microscope coupled with a tunable infrared laser (AFM-IR) was used to record highly spatially resolved infrared spectra of commercial purified PHB and native PHB within bacteria. For the first time, the crystallinity degree of native PHB within vesicle has been directly evaluated in situ without alteration due to the measure or extraction and purification steps of the polymer: native PHB is in crystalline state at 15% whereas crystallinity degree reaches 57% in commercial PHB. Chloroform addition on native PHB induces crystallization of the polymer within bacteria up to 60%. This possibility of probing and changing the physical state of polymer in situ could open alternative ways of production for PHB and others biopolymers.
Image: Spectrum of PHB within a bacterium recorded via AFM-IR. The amide I band is detected at 1658 cm-1 and the ester carbonyl band, characteristic of PHB presence, is revealed at 1739 cm-1.