Among emerging biomaterials, bioactive glasses (BGs) are being widely explored for various applications in tissue engineering. However, the effects of BGs (in particular BG ionic dissolution products) on immune cells and specifically on dendritic cells (DCs), which are the most potent antigen-presenting cells of the immune system, have not been previously investigated in detail. Such interactions between BGs and DCs must be assessed as a novel biocompatibility criterion for biomaterials, since, with the increased application possibilities of BGs, the modulation of the immune system may induce potential complications and undesired side effects. Indeed, the effects of BG exposure on specific immune cells are not well understood. Thus, in this study we investigated, for the first time, the effect of borate BGs doped with biologically active ions on specific immune cells, such as DCs and we further investigated the antibacterial properties of these borate BGs. The compositions of the borate BGs (B3) were based on the well-known 13–93 (silicate) composition by replacing silica with boron trioxide and by adding copper (3 wt%) and/or zinc (1 wt%). By performing an agar diffusion test, the antibacterial effect depending on the compositions of the borate BGs could be proved. Furthermore we found a dose-dependent immune modulation of DCs after treatment with borate BGs, especially when the borate BGs contained Zn and/or Cu. Depending on the ion concentration and the rise in pH, the phenotype and function of DCs were modified. While at low doses B3 and Zn-doped B3 BGs had no impact on DC viability, Cu containing BGs strongly affected cell viability. Furthermore, the surface expression of DC-specific activation markers, such as the major histocompatibility complex (MHC)-II, CD86 and CD80, was modulated. In addition, also DC mediated T-cell proliferation was remarkably reduced when treated with high doses of B3–Cu and B3–Cu–Zn BGs. Interestingly, the release of inflammatory cytokines increased after incubation with B3 and B3–Zn BGs compared to mock-treated DCs. Considering the essential role of DCs in the modulation and regulation of immune responses, these findings provide first evidence of phenotypic and functional consequences regarding the exposure of DCs to BGs in vitro.

Poly(glycerol-sebacate) (PGS) and poly(epsilon caprolactone) (PCL) have been widely investigated for biomedical applications in combination with the electrospinning process. Among others, one advantage of this blend is its suitability to be processed with benign solvents for electrospinning. In this work, the suitability of PGS/PCL polymers for the fabrication of composite fibers incorporating bioactive glass (BG) particles was investigated. Composite electrospun fibers containing silicate or borosilicate glass particles (13-93 and 13-93BS, respectively) were obtained and characterized. Neat PCL and PCL composite electrospun fibers were used as control to investigate the possible effect of the presence of PGS and the influence of the bioactive glass particles. In fact, with the addition of PGS an increase in the average fiber diameter was observed, while in all the composite fibers, the presence of BG particles induced an increase in the fiber diameter distribution, without changing significantly the average fiber diameter. Results confirmed that the blended fibers are hydrophilic, while the addition of BG particles does not affect fiber wettability. Degradation test and acellular bioactivity test highlight the release of the BG particles from all composite fibers, relevant for all applications related to therapeutic ion release, i.e., wound healing. Because of weak interface between the incorporated BG particles and the polymeric fibers, mechanical properties were not improved in the composite fibers. Promising results were obtained from preliminary biological tests for potential use of the developed mats for soft tissue engineering applications.

Wound dressings produced by electrospinning exhibit a fibrous structure close to the one of the extracellular matrix of the skin. In this article, electrospinning was used to fabricate fiber mats based on the well‐known biopolymers poly(ɛ‐caprolactone) (PCL) and methylcellulose (MC) using benign solvents. The blend fiber mats were cross‐linked using Manuka honey and additionally used as a biodegradable platform to deliver bioactive glass particles. It was hypothesized that a dual therapeutic effect can be achieved by combining Manuka honey and bioactive glass. Morphological and chemical examinations confirmed the successful production of submicrometric PCL‐MC fiber mats containing Manuka honey and bioactive glass particles. The multifunctional fiber mats exhibited improved wettability and suitable mechanical properties (ultimate tensile strength of 3–5 MPa). By performing dissolution tests using simulated body fluid, the improved bioactivity of the fiber mats by the addition of bioactive glass was confirmed. Additionally, cell biology tests using human dermal fibroblasts and human keratinocytes‐like HaCaT cells showed the potential of the fabricated composite fiber mats to be used as wound dressing, specially due to the ability to support wound closure influenced by the presence of bioactive glass. Moreover, based on the results of the antibacterial tests, it is apparent that an optimization of the electrospun fiber mats is required to develop suitable wound dressing for the treatment of infected wounds.

The dissolution properties and bioactivity of bioactive glasses (BGs) are mainly determined by their composition and glass network structure. Silicate BGs are arguable the most popular representatives of BGs. However, borate BGs have gained increasing interest due to their faster degradation rate. By adding boron trioxide in the silicate network, borosilicate BGs can be fabricated with controlled degradation rates. Since the kind and amount of network former determines the resulting BG properties, the aim of this study was to examine the glass structure of silicate, borosilicate and borate BGs. Also, the effect of changing the network former on the ability to fabricate BG scaffolds by the foam replica method was investigated. The resulting silicate, borosilicate, and borate scaffolds were further examined on their chemical, morphological, mechanical, and bioactive properties. Structural analyses showed that the introduction of boron trioxide into silicate BGs leads to the depolymerization of the silicate network. Accordingly, the ion release profile and the ability to form hydroxyapatite of the different scaffolds were affected. Thus, this study shows that tailored BG compositions with case‐specific properties can be designed and used to fabricate 3D scaffolds for potential use in bone tissue engineering.

Wound dressings able to deliver topically bioactive molecules represent a new generation of wound regeneration therapies. In this article, foams based on methylcellulose cross-linked with Manuka honey were used as platform to deliver borate bioactive glass particles doped additionally with copper. Borate bioactive glasses are of great interest in wound healing applications due to a combination of favorable properties, such as angiogenic and antibacterial properties. The multifunctional composite providing dual effects of the bioactive glass and Manuka honey was produced by freeze drying und the resulting foams exhibit a suitable morphology including a high porosity. Moreover, the performed tests showed improved wettability and mechanical performance by the addition of bioactive glass particles. Dissolution studies using simulated body fluid (SBF) and cell biology tests using relevant skin cells further proved the excellent bioactivity and the positive effects of the foams on cell proliferation and migration. Most interestingly, by the dual release of Manuka honey and ions from the copper doped bioactive glass, an antibacterial effect against E. coli and S. aureus could be obtained. Therefore, the multifunctional foams showed promising results as wound dressings for the treatment of infected wounds.