Paramagnetic Functionalization of Biocompatible Scaffolds for Biomedical Applications: A Perspective

Abstract

The burst of research papers focused on the tissue engineering and regeneration recorded in the last years is justified by the increased skills in the synthesis of nanostructures able to confer peculiar biological and mechanical features to the matrix where they are dispersed. Inorganic, organic and hybrid nanostructures are proposed in the literature depending on the characteristic that has to be tuned and on the effect that has to be induced. In the field of the inorganic nanoparticles used for decorating the bio-scaffolds, the most recent contributions about the paramagnetic and superparamagnetic nanoparticles use was evaluated in the present contribution. The intrinsic properties of the paramagnetic nanoparticles, the possibility to be triggered by the simple application of an external magnetic field, their biocompatibility and the easiness of the synthetic procedures for obtaining them proposed these nanostructures as ideal candidates for positively enhancing the tissue regeneration. Herein, we divided the discussion into two macro-topics: the use of magnetic nanoparticles in scaffolds used for hard tissue engineering for soft tissue regeneration.

Keywords: hard tissue; hydrogel; magnetic nanoparticles; scaffold; soft tissue; tissue engineering.

Figure 1

Schematic representation of the procedure used to fabricate the paramagnetic scaffolds [88].

Figure 2

Schematic representation of the procedure used to obtain the scaffolds in [92]. A powder of well-dispersed poly-l-lactide (PLLA)-polyglycolic acid (PGA) and magnetic responsive nanoparticles (MNPs) mixture was synthetized, melted by means of a laser and then solidified to obtain the paramagnetic scaffold.

Figure 3

According to the reference [108], the amplification of the external magnetic field obtained by the presence of the dispersed nanoparticles is represented in the figure by means of the red arrows: the MNPs work as nanoantennas in the amplification of the applied magnetic field.

Figure 4

Synthesis route used in [117,118] to obtain the functionalized gelatine used for the magneto-responsive microcapsules.

Figure 5

Schematic representation of the developed magnetic hydrogel based on 4-arm-PEG-vinylsulfone, HA and MMPs in [159] and of the magnetomechanical induced activation of Ca²⁺ channels: PIEZO2 and TRPV4. PIEZO2 channels are activated by the membrane stretching upon MMPs stimulations and TRPV4 channels were activated by the subsequent hydrogel deformation.

Figure 6

The 3D engineered aortic valve based on polyurethane/poly-L-lactic acid (TPU/PLLA) reported in reference [178]. In particular, 3.80% (w/v) MNPs were dissolved in TPU/PLLA mixture (50:50 v/v, 6.54 wt%); then, the mixture was subjected to electrospinning and collected into an aluminum foil based template of the valve obtaining the 3D scaffold reported.

Figure 7

Schematic representation of the parallel-plate flow system used in [181]. Cells functionalized with MNPs were fluxed in the system under a magnetic field of 0.3 T and were magnetically attracted by the MNPs decorated bacterial cellulose (BC) hydrogel.