Formation and characterization of β-cyclodextrin (β-CD) – polyethyleneglycol (PEG) – polyethyleneimine (PEI) coated Fe₃O₄ nanoparticles for loading and releasing 5-Fluorouracil drug

Abstract

In this work, β-cyclodextrin (β-CD) – polyethyleneglycol (PEG) – polyethyleneimine (PEI) coated iron oxide nanoparticles (Fe₃O₄-β-CD-PEG-PEI) were developed as drug carriers for drug delivery applications. The 5- Fluorouracil (5-FU) was chosen as model drug molecule. The developed nanoparticles (Fe₃O₄-β-CD-PEG-PEI) were characterized by various techniques such as Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM). The average particles size range of 5-FU loaded Fe₃O₄-β-CD, Fe₃O₄-β-CD-PEG and Fe₃O₄-β-CD-PEG-PEI nanoparticles were from 151 to 300 nm and zeta potential value of nanoparticles were from −43 mV to −20 mV as measured using Malvern Zetasizer.

Finally, encapsulation efficiency (EE), loading capacity (LC) and in-vitro drug release performance of 5-FU drug loaded Fe₃O₄-β-CD, Fe₃O₄-β-CD-PEG and Fe₃O₄-β-CD-PEG-PEI nanoparticles was evaluated by UV–vis spectroscopy. In-vitro cytotoxicity tests investigated by MTT assay indicate that 5-FU loaded Fe₃O₄-β-CD-PEG-PEI nanoparticles were toxic to cancer cells and non-toxic to normal cells. The in-vitro release behavior of 5-FU from drug (5-FU) loaded Fe₃O₄-β-CD-PEG-PEI composite at different pH values and temperature was studied. It was found that 5-FU was released faster in pH 6.8 than in the acidic mediums (pH 1.2), and the released quantity was higher. Therefore, the newly prepared Fe₃O₄-β-CD-PEG-PEI carrier exhibits a promising potential capability for anticancer drug delivery in tumor therapy.

Introduction

Superparamagnetic iron oxide nanoparticles (SPIONs) consist of cores made of iron oxides that can be targeted to the required area through external magnets. They have received much attention over the past decade because of their unique magnetic properties such as superparamagnetism, high field irreversibility, high saturation field, extra anisotropy contributions or shifted loops after field cooling [1], small size [2], limited toxicity [3], low cost of production [4] and ease of separation and detection [5], [6]. They have been garnering extensive attention in several biomedical applications, including magnetic resonance image (MRI) contrast agents [7], magnetic ferrofluids for hyperthermia [8], targeted drug delivery [9], and magnetically assisted separation [10]. To increase its stability, biocompatibility, prevent nanoparticle agglomeration and decrease the uptake by the reticuloendothelial system (RES), the surface of SPION has been coated by many types of hydrophilic materials and/or biocompatible polymers such as polyethyleneimine (PEI) [11], dextran, polyethylene glycol (PEG), poly-vinyl alcohol (PVA), chitosan, and others [12], [13], [14], [15], [16], [17]. The usage of SPIONs are considered to be a better carrier for the drug delivery system in the destined location as there were a number of side effects in the conventional oral delivery and injection of drug.

5-Fluorouracil (5-FU) is one of the oldest but still most extensively used anti-neoplastic agents. It is an antimetabolite of the pyrimidine analogue type with a low molecular weight, which is broadly used in the treatment of various kinds of solid tumors (such as the cancer of stomach, intestine, colon, pancreas, ovary, breast, etc.), alone or in combination chemotherapy regimes. In addition, an endurable therapeutic effect is impossible as it has a short in-vivo half-life [18]. To attain an effective clinical blood drug concentration, people very much opt to enhance drug mass or administer the drug to patients continually to enhance the toxic side effect of 5-FU [19]. To resolve this shortcoming, various microparticles (MPs) and nanoparticles encapsulating 5-FU have been prepared to control 5-FU to release slowly over certain ranges of time [20], [21], [22], [23].

β-Cyclodextrin (β-CD) is a type of cyclic oligosaccharides consisting of seven glucose units with lipophilic central cavities and a hydrophilic outer surface. It can be widely used in pharmaceutical excipient to improve the solubility, stability, and bioavailability of hydrophobic and biomolecular drugs [24], [25], [26], [27], [28]. It has been selected for encapsulation of 5-FU because it is a semi-natural product with extremely low toxicity and will enhance drug delivery through biological membranes [29]. Polyethyleneglycol (PEG) is commonly used in pharmaceutical and biomedical applications because of its exceptional physico-chemical and biological properties including hydrophilic property, solubility, non-toxicity, ease of chemical modification and absence of antigenicity and immunogenicity. It is, a classic pharmacokinetic stabilizer, which has been used to prolong magnetic nanoparticles circulations half-times in vivo, but almost exclusively for magnetic nanoparticles which are too small (<100 nm, often comprised of single domain cores <20 nm) to be sufficiently targeted [30], [31]. Polyethyleneimine (PEI) has been used as a multifunctional capping agent for further chemical modification of SPIONs to improve their suitability for use in MRI and gene/drug delivery [32], [33], [34]. It is a branched biopolymer with a high density of amine groups. The primary amines of PEI can effectively absorb protons to produce positive charge, rendering a strong affinity to cells [35], [36], [37].

In this work, we describe the formation and characterization of 5-FU loaded Fe₃O₄-β-CD, Fe₃O₄-β-CD-PEG and Fe₃O₄-β-CD-PEG-PEI nanocomposites as a possible and potential drug carrier for targeted drug delivery. Furthermore, the drug release properties, drug encapsulation efficiency (EE), loading capacity (LC) and in-vitro cytotoxicity for 5-FU loaded Fe₃O₄-β-CD, Fe₃O₄-β-CD-PEG and Fe₃O₄-β-CD-PEG-PEI nanocomposites were also investigated.