Institute of Fundamental Technological Research

Aiming at biomedical applications, the present work developed a new bio-nanocomposite fibrous mat based on natural rubber (NR) reinforced with 45S5 bioglass particles (BG) and cellulose nanowhiskers (CNW), which reveals excellent mechanical properties, good biocompatibility and bioactivity properties. Analyses of the specimens were conducted by means of morphological observa-tions (SEM) and thermal analysis (TG/DTG), as well as mechanical tests used to verify the effect of the incorporation of BG particles and CNW on the ultimate properties of these flexible NR-CWN/BG fibrous membranes. An SEM analysis revealed that all filaments possessed a ribbon-like morphology, with increasing diameters as the BG concentration increased. This likely results from an increased viscosity of the solution used for fiber blowing. In comparison with neat NR fibrous mats, the ultimate mechanical properties of bio-nanocomposites were sig-nificantly improved due to the presence of CNW and BG particles dispersed in the NR matrix. According to the TG/DTG analysis, the specimens' thermal stability was unaffected by the high BG content, and the thermal profiles were similar, with isoprene chains decomposition of the NR occurring between 350 and 450°C. In-vitro analysis on fibroblasts confirmed that the bio-nanocomposite fibrous mats are noncytotoxic. It was found that fibrous mats enhanced cellular growth and hold great promise for tissue engineering applications.

bioactive particles,cellulose nanowhiskers,fibrous mat bio-nanocomposite,natural rubber

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.

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

Over the last few years, traditional drug delivery systems (DDSs) have been transformed into smart DDSs. Recent advancements in biomedical nanotech-nology resulted in introducing stimuli-responsiveness to drug vehicles. Nano-
platforms can enhance drug release efficacy while reducing the side effects of drugs by taking advantage of the responses to specific internal or external stim-uli. In this study, we developed an electrospun nanofibrous photo-responsive DDSs. The photo-responsivity of the platform enables on-demand elevated drug release. Furthermore, it can provide a sustained release profile and pre-vent burst release and high concentrations of drugs. A coaxial electrospinning setup paired with an electrospraying technique is used to fabricate core-shell PVA-PLGA nanofibers decorated with plasmonic nanoparticles. The fabricated
nanofibers have a hydrophilic PVA and Rhodamine-B (RhB) core, while the shell is hydrophobic PLGA decorated with gold nanorods (Au NRs). The presence of plasmonic nanoparticles enables the platform to twice the amount of drug release besides exhibiting a long-term release. Investigations into the photo-responsive release mechanism demonstrate the system's potential as a “smart” drug delivery platform.

electrospun core-shell nanofibers,NIR-light activation,on-demand drug release,plasmonic nanoparticles,stimuli-responsive nanomaterials

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.

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