Investigation of the Impact of Poly(Ethylene Glycol)-Modulation of Poly(B-Hydroxybutyrate) Syntheses on Cell Interactions of the Resulting Polymers

Abstract

Poly(-hydroxybutyrate), PHB is a bacterial polyester known for its excellent bone compatibility, however, the material lacks blood and tissue compatibility. Poly(ethylene glycol), PEG,-modulated fermentation of Alcaligenes latus and Azotobacter vinelandii UWD was employed to yield copolymers consisting of PHB and PEG that exhibit diminished cell-adhesion surface properties. PEGs with molecular weights of 3400, 2000, and 400 as well as diethylene glycol, DEG, and pentaerythritol ethoxylate, PEE, were used in a concentration of 2% (w/v) for amending the fermentation broths. This modulation of the fermentation conditions did not influence polymer yields. However, the resulting copolymers had drastically reduced molecular weights, 82% less for the DEG-amended fermentation of A. latus. The reduction in molecular weight was attributed to an end-capping reaction of the nascent PHB-chain with PEG and/or early chain termination by water facilitated by the presence of the highly hydrophilic PEG-molecules. The formation of a covalent linkage was proven unambiguously by H-NMR-spectroscopic methods only for the copolymers obtained in the DEG-modified fermentations of both strains. Cell growth experiments using SK-MEL 28 and MDA-MB 231 cells were used for the evaluation of polymer-cell interaction. Copolymer films obtained from PEG-modulated syntheses showed significantly less cell Downloaded from adhesion with reductions in cell adhesions; up to 74% less in the two-day experiments (MDA-MB 231 on the copolymer obtained in DEG-modified fermentation of A. latus) and 48% less in the seven-day experiments (SK-MEL 28 on the copolymer obtained in PEG 400-modified fermentation of A. vinelandii UWD). In the two-day experiments, no differences in the cellinteraction was observed between the polymers obtained from two different bacterial sources, the polymers differed in their long-term, seven-day, cell interaction with copolymers obtained from A. vinelandii UWD maintaining more effective cell repulsion.

PEGylation and BioPEGylation of Polyhydroxyalkanoates: Synthesis, Characterisation and Applications

“…In this study, cell adhesion was significantly affected by the presence of the PEG hydrophilic end groups, with reductions in cell attachments to hybrids ranging from 22 to 74%. The greatest reduction was found with PHB-co-PEG106, (Zanzig et al 2003). .…”

“…Thus, while 5% (w/v) PEG-106 in the growth media resulted in no PHA synthesis, 10% (w/v) of PEG-10,000 still showed some biopolymer synthesis, although the impact was greater than that observed when the studies were conducted with R. eutropha (Ashby et al 1997). Similarly, additions to cultivations of A. vinelandii UWD of 2% (w/v) of various PEGs from PEG-106 to PEG-3400 also resulted in variable polymer yields (Zanzig et al 2003). P(HB-co-HV) synthesis by R. ruber was influenced by the presence of 0.2-5% (w/v) PEG-200, with a reduction in scl-PHA yield of up to 50% (Alvarez et al 1997).…”

“…Scholz and coworkers investigated the interactions of various bioPEGylated PHB samples with skin melanoma and human breast adenocarcinoma cells (Zanzig et al 2003). In this study, cell adhesion was significantly affected by the presence of the PEG hydrophilic end groups, with reductions in cell attachments to hybrids ranging from 22 to 74%.…”

“…Thus, PEG modulated bioprocessing of PHAs may offer a technique to control PHA physiochemical and material properties. In addition, characterisations of natural-synthetic hybrids of bioPEGylated PHAs suggest that these hybrids may also possess additional properties when compared to their PHA counterparts (Zanzig et al 2003;Foster et al 2005). Concurrent cultivations of A. latus from the same inoculums have shown that the PHB-co-PEG106 hybrid, while possessing a lower molecular weight compared to its PHB counterpart, also had significantly different physiochemical and material properties.…”

The effect of poly(3-hydroxybutyrate) modification by poly(ethylene glycol) on the viability of cells grown on the polymer films

“…На "гладкой" поверхности плёнки из этого полимерного композита клетки росли статистически значимо хуже на 1 и 2 сут., чем на контрольном образце "гладкой" поверхности ПОБ. Это может свидетельствовать об отрицательном влиянии ПЭГ-300 на жизнедеятельность культивируемых in vitro клеток, что было показано ранее другими исследователями [12,13]. Кроме того, эти данные свидетельствуют об отсутствии отрицательного влияния незначительных остатков невымывшегося ПЭГ из исследуемых композитов ПЭГ/ПОБ на жизнедеятельность растущих на их поверхности клеток.…”