Study of Biological Degradation of New Poly(Ether-Urethane-Urea)s Containing Cyclopeptide Moiety and PEG by Bacillus amyloliquefaciens Isolated from Soil

Abstract

The present work for the first time investigates the effect of Bacillus amyloliquefaciens, M3, on a new poly(ether-urethane-urea) (PEUU). PEUU was synthesized via reaction of 4,4'-methylenebis(4-phenylisocyanate) (MDI), L-leucine anhydride cyclopeptide (LACP) as a degradable monomer and polyethylene glycol with molecular weight of 1000 (PEG-1000). Biodegradation of the synthesized PEUU as the only source for carbon and nitrogen for M3 was studied. The co-metabolism biodegradation of the polymer by this organism was also investigated by adding mannitol or nutrient broth to the basic media. Biodegradation of the synthesized polymer was followed by SEM, FT-IR, TGA, and XRD techniques. It was shown that incubation of PEUU with M3 resulted in a 30-44 % reduction in polymer's weight after 1 month. This study indicates that the chemical structure of PEUU significantly changes after exposure to M3 due to hydrolytic and enzymatic degradation of polymer chains. The results of this work supports the idea that this poly(ether-urethane) is used as a sole carbon source by M3 and this bacterium has a good capability for degradation of poly(ether-urethane)s.

Evaluation of biological degradation of polyurethanes

“…Thermoplastic poly(ether urea) PU (Rafiemanzelat et al, 2015) Bacillus pumilus NMSN-1d Polyester PU coating (Impranil) (Nair and Kumar, 2007) Bacillus subtilis MZA-75 Thermoplastic polyester PU (Shah et al, 2016) (Shah et al, 2013b) Chryseobacterium meningosepticum Polyester PU foam (Cangemi et al, 2008) Comamonas acidovorans TB-35 Thermoplastic polyester PU (Akutsu et al, 1998;Nakajima-Kambe et al, 1997;Nakajima-Kambe et al, 1995) Thermoplastic polyether PU (Nakajima-Kambe et al, 1995) Corynebacterium sp. Thermoplastic polyester PU (Kay et al, 1993) (Shah et al, 2008a) Polyester PU foam (Kay et al, 1991) Escherichia coli Thermoplastic poly(ether urea) PU (Rafiemanzelat et al, 2013) Micrococcus sp.…”

“…It is not recommended to sterilize TPUs by autoclaving for microbial experiments as most of the TPU becomes liquid-like or very soft at autoclaving temperatures (121°C). Degradation can occur e.g., a study comparing autoclaved and non-autoclaved poly(ether urea) PU material revealed that no weight loss was observed after autoclaving but a surface alteration appeared, leading to bias in degradation measurement (Rafiemanzelat et al, 2015). Alternatives such as rinsing with ethanol (Cosgrove et al, 2010;Mathur and Prasad, 2012), UV exposure (Gogoi and Karak, 2014) or both (Osman et al, 2018) are thus frequently employed to sterilize the samples.…”

“…For instance, if the degradation is too superficial and too low to lead to detectable product release, the test will be considered as inefficient as no weight loss will be measured. Therefore, weight loss measurement must be associated with a surface analysis of the sample (Rafiemanzelat et al, 2015) in case of a low degradation extent, or to analyze the early steps of the degradation. It is necessary to remove all the biological materials that can remain on the polymer surface.…”

“…For instance, a poly(ether urea) PU was incubated for one month with a strain of Bacillus. The observed changes in the material thermal stability attested for a higher proportion of hard segments and consequently a degradation occurring preferentially at the SS domains containing ether bonds (Rafiemanzelat et al, 2015).TGA is perfectly appropriate to analyze cross-linked foams. In their study, Gomez et al, compared the composting of a fossil-based and a biobased PU foam (Gómez et al, 2014).…”

Recent advances in design and applications of biomimetic self-assembled peptide hydrogels for hard tissue regeneration

“…Thus, the development of suitable biomaterials for hard tissue repair and regeneration is an important task, especially for societies with a large elderly population [2]. So far, several biomaterials such as metal implants, allografts, autografts, ceramic, demineralized matrix, polymers, and composites have been applied for hard tissue regeneration [3][4][5]. Although conventional biomaterials like ceramics, bio-glass, and bone cement are significant for restoring hard tissues, they fail in promoting self-tissue regeneration, which is critical for healthy bones.…”