Controlled Anchoring of Iron Oxide Nanoparticles on Polymeric Nanofibers: Easy Access to Core@Shell Organic–Inorganic Nanocomposites for Magneto-Scaffolds

Abstract

Composites combining superparamagnetic iron oxide nanoparticles (SPIONs) and polymers are largely present in modern (bio)materials. However, while SPIONs embedded in polymer matrices are classically reported, the mechanical and degradation properties of the polymer scaffold are impacted by the SPIONs. Therefore, the controlled anchoring of SPIONs onto polymer surfaces is still a major challenge. Herein, we propose an efficient strategy for the direct and uniform anchoring of SPIONs on the surface of functionalized-polylactide (PLA) nanofibers via a simple free ligand exchange procedure to design PLA@SPIONs core@shell nanocomposites. The resulting PLA@SPIONs hybrid biomaterials are characterized by electron microscopy (SEM and TEM) and EDXS analysis, to probe the morphology and detect elements present at the organic/inorganic interface, respectively. A monolayer of SPIONs with a complete and homogeneous coverage is observed on the surface of PLA nanofibers. Magnetization experiments show that magnetic properties of the nanoparticles are well-preserved after their grafting on the PLA fibers and that the size of the nanoparticles does not change. The absence of cytotoxicity, combined with a high sensitivity of detection in MRI both in vitro and in vivo make these hybrid nanocomposites attractive for the development of magnetic biomaterials for biomedical applications.

Long-term in vivo performances of polylactide/iron oxide nanoparticles core–shell fibrous nanocomposites as MRI-visible magneto-scaffolds

“…3.1 Preparation and degradation of PLA@SPIONs nanofibers PLA@SPIONs nanofibers were prepared according to our recently-reported procedure (Scheme 1). 16 Random PLA mesh nanofibers were first functionalized with phosphonic acid groups following a two step-procedure involving the propargylation of PLA nanofibers followed by thiol-yne photoaddition of 12-mercaptododecylphosphonic acid. In a next step, oleic acid-functionalized SPIONs with a diameter around 18 nm (Figure S1), were anchored onto the PLA nanofibers, thanks to the ligand exchange taking place between the carboxylic groups present at the surface of the SPIONs and the phosphonic acid groups present at the surface of the PLA nanofibers.…”

“…The functionalization of PLA fibers with phosphonic acid groups was carried out in two steps as previously described by our group. 16 In brief, PLA fibers were first propargylated in diethyl ether at -50°C by an anionic activation using LDA, followed by the addition of propargyl bromide. In a second step, 12-mercaptododecylphosphonic acid (HS-(CH2)12-P(O)(OH)2) was grafted on the PLA fibers thanks to a thiol-yne photoaddition reaction under UV between the free alkyne groups present at the surface of the PLA fibers and the thiol functionality of the phosphonic ligand.…”

“…The anchoring of the oleic acid-functionalized SPIONs to the surface of the phosphonic acidfunctionalized PLA fibers was carried out according to a ligand exchange procedure recently described by our group. 16 In short, freshly prepared oleic acid-functionalized SPIONs were suspended in cyclohexane/ acetone (3:1 v:v) and were sonicated for 2h under argon. PLA meshes were then immersed in the suspension of SPIONs and the ligand exchange was let to proceed for 18h at room temperature under argon in the dark.…”

“…8,15 To overcome these drawbacks, we have recently reported on a new strategy to prepare PLA@SPIONs nanofibers with a controlled interface: a quasi-monolayer of SPIONs anchored at the surface of PLA electrospun fibers. 16 Such well-defined magnetic nanocomposites are expected to present major benefits over the existing magnetic polymeric composites reported in the literature: (i) no change in the mechanical and degradation properties of the polymeric phase due to surface immobilization of the inorganic particles (rather than their mixing in the polymer matrix), (ii) enhanced magnetic properties through improved dipolar interactions of the surface anchored superparamagnetic nanoparticles, (iii) enhanced MRI sensitivity, (iv) lower quantities of magnetic nanoparticles for high magnetic properties and therefore lower biocompatibility concerns. Some of these points were confirmed in our proof of concept study.…”

Efficient Flame Retardancy, Smoke Suppression, and Mechanical Enhancement of β‐FeOOH@Metallo‐Supramolecular Polymer Core–Shell Nanorod Modified Epoxy Resin

“…The surface modification strategy to get a core–shell structure has been proved to be an efficient way to prepare organic‐inorganic composites. [ 16,17 ] FeOOH has a cubic close packed structure with Fe 3+ locating in octahedra void, which provides an approach for the surface decoration by coordination between Fe 3+ and metallo‐supramolecular. [ 18,19 ] Inspiring by the strategy of multi‐element flame retardants, [ 20,21 ] the coating of FeOOH with organic flame retardant containing phosphorus, silicon, or nitrogen is potential to enhance the flame‐retardant efficiency.…”