Effect of the Polyacrylamide Ferrogel Elasticity on the Cell Adhesiveness to Magnetic Composite

Abstract

Biocompatible polyacrylamide gels are widely required for the development of mechanically “soft” magnetic material for the purposes of different biomedical applications. In this work, ferrogels were synthesized by radical polymerization of acrylamide in a stable aqueous suspension of magnetic maghemite [Formula: see text]-Fe[Formula: see text]O[Formula: see text] nanoparticles (MNPs) with the median value in diameter of 11.4[Formula: see text]nm fabricated by laser target evaporation. Gel network density was set to 1:100, the concentrations of embedded MNPs were fixed at 0.00%, 0.25%, 0.50%, 0.75% or 1.0% by weight. Ferrogels’ Young’s modulus and affinity to the human dermal fibroblasts adhesiveness were tested. To estimate the cells adhesive activity to gels, the adhesion index was calculated as the number of adhered cells divided by the number of cells sown and multiplied by 100%. The gradual increase of MNPs concentration in the gel network resulted in the significant increase of ferrogel’s Young’s modulus and cells adhesion activity. In particular, at the MNPs concentration of 0.25%, the modulus and the adhesion index were equal to [Formula: see text]30[Formula: see text]kPa and [Formula: see text]90%, correspondingly. The adhesion index at highest MNPs concentration of 1.0% was close to 100% and modulus to [Formula: see text]40[Formula: see text]kPa. The increase of cells adhesiveness rise with MNPs concentration closely correlated with the direct impact of MNPs on the gel stiffness.

The Contribution of Magnetic Nanoparticles to Ferrogel Biophysical Properties

“…The laboratory setup for mechanical testing of gels was used as described early [ 30 , 31 ]. A cylindrical ferrogel sample (~7 mm in length and ~10 mm in diameter) placed in a bath filled with Hanks’ solution was clamped vertically between two parallel plates connected to the levers of the force transducer and the linear motor equipped with an optical transducer for the gel length measurement.…”

“…The possibility of ferrogel usage for cellular scaffolds has been reported in a number of studies [ 27 , 28 , 29 ]. For instance, in our early works, we demonstrated a good compatibility of cells with polyacrylamide-based ferrogels [ 30 , 31 ]. In particular, it was found that the adhesive activity of human dermal fibroblasts become larger with the increase of MNPs concentration in the composite, so that at the 1.0% weight fraction of MNPs in ferrogel, the cell adhesion appeared to be comparable to the cultural plastic widely used in cellular technologies.…”

“…This kind of study is almost absent in the literature because the majority of the techniques offer only a small batch size. Here, we use the same batch of nanoparticles, as in our previous works [ 30 , 31 ], in order to insure the validity of the comparison of the results.…”

Ferrogels Ultrasonography for Biomedical Applications

“…The elastic properties of the gels were evaluated by mechanical testing of the samples as described elsewhere [6,8,10]. Briefly, stepped strains for compression of up to 20% of the initial length were set to samples of gels while using a linear motor with a step of 1–2%.…”

“…Different studies had established the fact that the elastic properties of PAA ferrogels can significantly vary, depending on the details of synthesis conditions, as well as change their mechanical characteristics in response to an external magnetic field [4,7,8]. It is also known that polyacrylamide ferrogels have low toxicity and good compatibility to living cells [9,10]. Based on this advantage, PAA ferrogels have been used as substrates (scaffolds) for cell culturing for the needs of cellular technologies and tissue engineering [11].…”