Facile Solvothermal Synthesis of Mesostructured Fe₃O₄/Chitosan Nanoparticles as Delivery Vehicles for pH‐Responsive Drug Delivery and Magnetic Resonance Imaging Contrast Agents

Abstract

We report a facile fabrication of a host-metal-guest coordination-bonding system in a mesostructured Fe3O4/chitosan nanoparticle that can act as a pH-responsive drug-delivery system. The mesostructured Fe3O4/chitosan was synthesized by a solvothermal approach with iron(III) chloride hexahydrate as a precursor, ethylene glycol as a reducing agent, ammonium acetate as a porogen, and chitosan as a surface-modification agent. Subsequently, doxorubicin (DOX), acting as a model drug (guest), was loaded onto the mesostructured Fe3O4/chitosan nanoparticles, with chitosan acting as a host molecule to form the NH2-Zn(II)-DOX coordination architecture. The release of DOX can be achieved through the cleavage of coordination bonds that are sensitive to variations in external pH under weakly acidic conditions. The pH-responsive nature of the nanoparticles was confirmed by in vitro releases and cell assay tests. Furthermore, the relaxation efficiency of the nanoparticles as high-performance magnetic resonance imaging contrast agents was also investigated. Experimental results confirm that the synthesized mesostructured Fe3O4/chitosan is a smart nanovehicle for drug delivery owing to both its pH-responsive nature and relaxation efficiency.

Nanoparticles in biomedical applications

“…However, this form of iron oxide has a tendency to oxidise so coating with a biocompatible shell is required. Some examples of coatings include polymers [9,32,43,49,56,63,65], ceramics [17,25,59] and metals [15]. Coating with a shell offers many advantages such as it prevents agglomeration and helps with further functionalisation and conjugation to proteins, enzymes, antibodies and anticancer drugs.…”

“…Coating with a shell offers many advantages such as it prevents agglomeration and helps with further functionalisation and conjugation to proteins, enzymes, antibodies and anticancer drugs. Iron oxide nanoparticles have been investigated for use in magnetic hyperthermia treatment [20,21,[31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46]55], targeted drug delivery and contrast agents in magnetic resonance imaging (MRI) 34,41,56,62]. The magnetic properties of iron oxide nanoparticles can be improved by doping with magnetically susceptible elements such as manganese (Mn), cobalt (Co) and nickel (Ni) [103] …”

“…A lot of literature have focused on iron oxide nanoparticles because of their superior chemical, biological and magnetic properties including chemical stability, non-toxicity, biocompatibility, high saturation magnetisation and high magnetic susceptibility [5][6][7][8]. These properties allow for its use in many biomedical applications; bioimaging 34,41,56,62], hyperthermia [20,21,[31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46]55], drug delivery , cell labelling [26,70] and gene delivery [71][72][73][74][75][76][77]. From our most recent review, it was seen that other magnetic nanomaterials such as Fe-Co, Cu-Ni, Fe-Ni, Co-Fe 2 O 4 and Mn-Fe 2 O 4 , nanoparticles are being investigated for use in bioimaging [78][79][80][81][82][83][84][85][86]…”

Theranostic Nanoparticles and Their Spectrum in Cancer

“…To eliminate this unwanted process, coating with a biocompatible shell, such as a polymer [92], ceramics [93] or metals [13], is needed in order to prevent conglomeration. In addition, iron oxide NPs can be functionalized with proteins, antibodies, enzymes and anticancer drugs [13] and are investigated for different applications including magnetic hyperthermia [94], contrast agents in MRI (magnetic resonance imaging) [95], targeted drug delivery [96], multimodal imaging and gene therapy [61].…”

Solvothermal synthesis of porous Fe3O4 nanoparticles for humidity sensor application

“…Several methods are used to synthesize magnetic material; e.g., sol-gel [18,19], reverse micelle [20], co-precipitation process [21,22], γ-ray irradiation [23,24], non-aqueous route [25], microwave plasma synthesis [26], and hydrothermal treatment [27,28]. Among these methods, solvothermal is a powerful technique to control the morphology and size of the nanostructure [29][30][31][32][33][34]. By this method, we can control the size, crystallinity, and the shape distribution of metal oxide nanostructures and synthesize well-crystallized and mono-dispersed ferrite nanostructures.…”