Chitosan membranes containing micro or nano-size bioactive glass particles: evolution of biomineralization followed by in situ dynamic mechanical analysis

Abstract

A new family of biodegradable polymer/bioactive glass (BG) composite materials has emerged based on the availability of nano-sized bioactive particles. Such novel biocomposites can have enhanced performance, in terms of mechanical properties and bioactivity, and they can be designed to be used in bone regeneration approaches. In this work, membranes of chitosan (CTS) and chitosan with bioactive glass (BG) both micron and nano sized particles (CTS/μBG, CTS/nBG, respectively) were prepared by solvent casting. Microstructural and mechanical properties were evaluated in order to compare the effects of the incorporation of micro (μBG) and nano (nBG) particles in the chitosan matrix. In vitro bioactivity tests were performed to characterize the apatite layer that is formed on the surface of the material after being immersed in simulated body fluid (SBF). The biomineralization process on the biomaterials was also followed using non-conventional dynamic mechanical analysis (DMA), both online and offline. In such DMA experiments, the change in the storage modulus, E', and the loss factor, tan δ, were measured as a function of the immersion time in SBF. The results demonstrated that CTS/nBG membranes possess enhanced mechanical properties and higher bioactivity in comparison with the CTS/μBG membranes. Such results suggest the potential of nBG for the development of bioactive composites for bone regeneration applications.

A new insight into in vitro behaviour of poly(ε-caprolactone)/bioactive glass composites in biologically related fluids

“…These findings are consistent with results obtained in our previous works [25,26], as well as those of other authors [52,53]. Moreover, it was shown that the larger surface area of smaller glass particles provides more effective ion release, enhancing the ability of HAp layer formation on the composite surfaces [22].…”

“…New bands can be assigned to O-P-O bending mode and P-O stretching mode, respectively. Furthermore, new absorption band corresponding to the carbonate groups CO 3 2-in HCA was found at 873 cm -1 (outof-plane bending mode) [22]. In the case of A2-PCL composite films, the almost complete vanishing of bands characteristic for PCL was observed after incubation, confirming high thickness and uniformity of the formed CaP layer.…”

Poly(ε-caprolactone)-based membranes with tunable physicochemical, bioactive and osteoinductive properties

“…Jaakkola et al [51] and Caridade et al [31] observed that faster consumption of both Ca and P, as well as faster release of Si occurred in case of composites containing smaller BG particles size. Apart from Ca release/consumption profiles affected by above-mentioned compensation process, these findings correlate with results obtained in present work only for materials produced with the use of TIPS method.…”

“…Furthermore, the larger surface area of BG particles allows a faster ion exchange with the surrounding medium enhancing ability of HAp layer formation on the composite surfaces [31]. Our previous studies indicated that the uniform distribution of smaller BG particles (A2\3 μm) in the PCL matrix of solvent-cast films resulted in crystallization of carbonated hydroxyapatite (HCA) on the AS surface.…”

“…FTIR spectra of all composite materials revealed appearance of new two bands in the range of 560-602 cm −1 and single intensive band at 1020 cm −1 originated from CaP precipitations just after 3 days of soaking, and gradual reduction in intensity of bands characteristic for PCL. New bands can be assigned to O-P-O bending mode and P-O stretching mode, respectively [31]. The reduction in intensity of PCL bands can be connected with increasing thickness and/or tightness of CaP layer covering material surface.…”