Transport of silver nanoparticles from nanocomposite Ag/alginate hydrogels under conditions mimicking tissue implantation

Abstract

The aim of this work was to assess phenomena occurring during AgNP transport from nanocomposite Ag/alginate hydrogels under conditions relevant for potential biomedical applications as antimicrobial soft tissue implants. First, we have studied AgNP migration from the nanocomposite to the adjacent alginate hydrogel mimicking soft tissue next to the implant. AgNP deposition was carried out by the initial burst release lasting for ?24 h yielding large aggregates on hydrogel surfaces and smaller clusters (?400 nm in size) inside. However, the overall released content was low (0.67%) indicating high nanocomposite stability. In the next experimental series, release of AgNPs, 10?30 nm in size, from Ag/alginate microbeads in water was investigated under static conditions as well as under continuous perfusion mimicking vascularized tissues. Mathematical modeling has revealed AgNP release by diffusion under static conditions with the diffusion coefficient within the Ag/alginate hydrogel of 6.9x10?19 m2 s?1. Conversely, continuous perfusion induced increased AgNP release by convection with the interstitial fluid velocity estimated as 4.6 nm s?1. Overall, the obtained results indicated the influence of hydrodynamic conditions at the implantation site on silver release and potential implant functionality, which should be investigated at the experimentation beginning using appropriate in vitro systems. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III 45019]

Functional bioreactor characterization to assess potentials of nanocomposites based on different alginate types and silver nanoparticles for use as cartilage tissue implants

“…The value determined in the present study was somewhat higher than the Ag + diffusion coefficient of 1.5 × 10 −14 m 2 /s determined in a Ag/PVA hydrogel immersed in a phosphate buffer pH = 7, by the integral form of the Fick's diffusion model approximated for short times . On the contrary, significantly lower diffusion coefficients of AgNP/Ag + of 4.6 × 10 −19 and 6.9 × 10 −19 m 2 /s were obtained in Ag/alginate microbeads in water under static conditions by applying the same diffusion model in differential form as in the present work . Slower diffusion rates in these cases were expected due to higher stability of the polymer network in water as compared to the culture medium containing Na + , which provokes the network swelling and, thus, diffusion enhancement.…”

“…Since the disc swelling was relatively fast (within 24 h), constant disc dimensions of 17 mm in diameter and 4 mm thickness were assumed. The released silver concentration in medium over time, c m , is calculated as a difference between the initial silver content in the discs c o and the average silver content in discs at each time point, 〈 c n 〉: where V is the disc volume and V m is the medium volume in the system. The average silver concentration within the disc at each time point can be calculated by the equation: where X is the disc thickness.…”

“…The change in AgNP concentration within the Ag/alginate discs, c n , was described by the Eq. (1) with addition of the advection term yielding the advection–diffusion equation as also used previously: where x is the axial coordinate, u is the net fluid velocity through the disc and D” is the apparent diffusion coefficient of AgNPs/Ag + in Ag/alginate discs that negligibly swelled.…”

“…84 On the contrary, significantly lower diffusion coefficients of AgNP/Ag + of 4.6 × 10 −19 and 6.9 × 10 −19 m 2 /s were obtained in Ag/alginate microbeads in water under static conditions by applying the same diffusion model in differential form as in the present work. 49,61 Slower diffusion rates in these cases were expected due to higher stability of the polymer network in water as compared to the culture medium containing Na + , which provokes the network swelling and, thus, diffusion enhancement.…”

Application of Metal Nanoparticle–Hydrogel Composites in Tissue Regeneration

“…The NPs might not only directly be taken up by the cells in exposed organs, but also translocated to other organs, causing undesired toxicity or other adverse effects [95]. Kostic et al have conducted a study to assess the translocation of Ag from hydrogel composite, and it has been concluded that the release of Ag was dependent on the hydrodynamic conditions at the implantation site [96]. In the in vivo study conducted by Alarcon et al, the systemic distribution of Ag NPs after the implantation of an Ag NP–collagen hydrogel was investigated.…”