The general concept of tissue engineering is to restore biological function by replacing defective tissues with implantable, biocompatible, and easily handleable cell-laden scaffolds. In this study, osteoinductive and osteoconductive super paramagnetic Fe3O4 nanoparticles (MNP) and hydroxyapatite (HAP) nanoparticles were incorporated into a di-block copolymer based thermo-responsive hydrogel, methoxy(polyethylene glycol)-polyalanine (mPA), at various concentrations to afford composite, injectable hydrogels. Incorporating nanoparticles into the thermo-responsive hydrogel increased the complex viscosity and decreased the gelation temperature of the starting hydrogel. Functionally, the integration of inorganic nanoparticles modulated bio-markers of bone differentiation and enhanced bone mineralization. Moreover, this study adopted the emerging method of using either a supplementary static magnetic field (SMF) or a moving magnetic field to elicit biological response. These results demonstrate that combining external (magnet) and internal (scaffold) magnetisms is a promising approach for bone regeneration.

Blending 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ), a high electron affinity organic molecule, with N,N′-bis-(1-naphyl)-N,N′-diphenyl-1,1′-biphenyl′-4,4′-diamine (NPB) creates the charge-transfer-complex molecules and modulates the magnetoconductance (MC) responses of devices by an applied electrical bias. A negative MC response (−0.60%) is observed for the device made of NPB:F4-TCNQ(30%) film as the active layer, which has a distinct characteristic to negligible MC responses in pristine NPB- and F4-TCNQ-based devices. We attribute the MC responses to the magnetic-field-dependent transport of injected charge carriers through charge-transfer-complex molecules in the NPB:F4-TCNQ system, which are varied with the F4-TCNQ blending concentrations and the injection of minority charge carriers. Results of this study demonstrate a turning point of MC responses at the bias voltage near the threshold of the bipolar injection.