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Abstract:
The solution blow spinning technique was used to fabricate a new biocomposite fibrous mat consisting of natural rubber (NR) and polyhydroxybutyrate (PHB) bioblend, with various loads of 45S5 bioglass (BG) particles. According to SEM analysis, NR fibers exhibited ribbon-like morphologies, whereas the addition of PHB resulted in improved fiber formation and a reduction in their diameter. In NR-PHB/BG biocomposites with varying BG loadings, typical thermal degradation events of PHB (stage i) and NR (stage ii) were observed. In comparison with pure PHB, the TG/DTG curves of NR-PHB/BG specimens revealed a lower stage i degradation peak. Such an outcome is possibly due to the fact that PHB in the NR-PHB fibers is located predominantly at the surface, that is, PHB is more susceptible to thermal degradation. The NR-PHB/BG biocomposite possessed an increased stiffness due to the addition of PHB and BG, resulting in an increased stress and a decreased strain at rupture compared to the pure NR and NR-PHB mats. DMA analysis revealed two well-defined regions, above and below the glass transition temperature (Tg), for the storage modulus (E') of the NR-PHB/BG specimens. The values of E' were in both regions for NR-PHB/BG specimens increased at higher BG content. The measured tanδ = E″/E' was used to determine the Tg value for all specimens, with Tg found to be in the −49 to −46°C range. Finally, NR-PHB/BG biocomposite fibrous were proven noncytotoxic by in-vitro testing on fibroblasts. These biocomposites enhanced cell growth, holding great promise for tissue engineering applications.

Keywords:
45S5 bioglass, biocomposite fibrous mat, biomedical applications, natural rubber, polyhydroxybutyrate, solution blow spinning

Abstract:
Antimicrobial nonwovens for single use applications (e.g., diapers, sanitary napkins, medical gauze, etc.) are of utmost importance as the first line of defense against bacterial infections. However, the utilization of petrochemical nondegradable polymers in such nonwovens creates sustainability-related issues. Here, sustainable poly(hydroxybutyrate) (PHB) and ε-poly-l-lysine (ε-PLL) submicro- and microfiber-based antimicrobial nonwovens produced by a novel industrially scalable process, solution blowing, have been proposed. In such nonwovens, ε-PLL acts as an active material. In particular, it was found that most of ε-PLL is released within the first hour of deployment, as is desirable for the applications of interest. The submicro- and microfiber mat was tested against C. albicans and E. coli, and it was found that ε-PLL-releasing microfibers result in a significant reduction of bacterial colonies. It was also found that ε-PLL-releasing antimicrobial submicro- and microfiber nonwovens are safe for human cells in fibroblast culture. Mechanical characterization of these nonwovens revealed that, even though they are felt as soft and malleable, they possess sufficient strength, which is desirable in the end-user applications.

Keywords:
PHB submicro- and microfibers, antimicrobial nonwovens, ε-PLL release, E. coli, C. albicans