Graphene Oxide versus Carbon Nanofibers in Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Films: Degradation in Simulated Intestinal Environments.

Ariagna L Rivera-Briso,José Luis Aparicio-Collado,Roser Sabater I Serra,Ángel Serrano-Aroca

doi:10.3390/polym14020348

Abstract

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a microbial biodegradable polymer with a broad range of promising industrial applications. The effect of incorporation of low amounts (1% w/w) of carbon nanomaterials (CBNs) such as 1D carbon nanofibers (CNFs) or 2D graphene oxide (GO) nanosheets into the PHBV polymer matrix affects its degradation properties, as it is reported here for the first time. The study was performed in simulated gut conditions using two different media: an acidic aqueous medium (pH 6) and Gifu anaerobic medium. The results of this study showed that the incorporation of low amounts of filamentous 1D hydrophobic CNFs significantly increased the degradability of the hydrophobic PHBV after 3 months in simulated intestinal conditions as confirmed by weight loss (~20.5% w/w in acidic medium) and electron microscopy. We can attribute these results to the fact that the long hydrophobic carbon nanochannels created in the PHBV matrix with the incorporation of the CNFs allowed the degradation medium to penetrate at ultrafast diffusion speed increasing the area exposed to degradation. However, the hydrogen bonds formed between the 2D hydrophilic GO nanosheets and the hydrophobic PHBV polymer chains produced a homogeneous composite structure that exhibits lower degradation (weight loss of ~4.5% w/w after three months in acidic aqueous medium). Moreover, the water molecules present in both degradation media can be linked to the hydroxyl (-OH) and carboxyl (-COOH) groups present on the basal planes and at the edges of the GO nanosheets, reducing their degradation potential.

Highlights

The development of new materials for biomedical applications constitutes a consolidated area of research of the 21st century and much progress have been achieved in the last two decades [1,2,3,4,5,6,7,8,9,10]
(1% w/w) into PHBV might affect the degradability of PHBV in human gut conditions reproduced by acid aqueous medium and simulated intestinal medium Gifu anaerobic medium (GAM)
Due to the different polarity of carbon nanofibers (CNFs) and graphene oxide (GO) nanosheets, we expect to observe a different effect on the degradation of the polar PHBV hydrophobic biopolyester polymer in this comparative study

Summary

Introduction

The development of new materials for biomedical applications constitutes a consolidated area of research of the 21st century and much progress have been achieved in the last two decades [1,2,3,4,5,6,7,8,9,10] In this regard, polyhydroxyalkanoates (PHAs) are a very promising family of biodegradable and renewable lineal bacterial biopolyester polymers [11,12,13,14,15,16,17,18]. We hypothesize here that the incorporation of a low amount of GO nanosheets or CNFs (1% w/w) into PHBV might affect the degradability of PHBV in human gut conditions reproduced by acid aqueous medium (pH 6) and simulated intestinal medium GAM. Due to the different polarity of CNFs and GO nanosheets, we expect to observe a different effect on the degradation of the polar PHBV hydrophobic biopolyester polymer in this comparative study

Materials

Nanocomposite Film Preparation

Degradation Analysis

Electron Microscopy Observation

Statistical Analysis

Results and Discussion