Abstract
This work has focused on the synthesis of three nanosystems composed of superparamagnetic iron oxide nanoparticles (SPIONs) coated either with a carboxylate platinum(IV) complex (PD = cis,cis,trans-[Pt(NH3)2Cl2(HOOCCH2CH2COO)(OH)]) or with platinum(II) complex functionalized dextrans (DexPt1 = [Pt(Dex-NH2)Cl3] and DexPt2 = [Pt(Dex-NH2)(NH3)2(H2O)]). All nanosystems have shown superparamagnetic behavior. Powder X-ray diffraction (XRD) has confirmed that the SPIONs were iron oxide phase and transmission electron microscopy (TEM) has shown average size of 6 nm (M6). Characterization of the nanosystems by inductively coupled plasma atomic emission spectroscopy (ICP AES) has revealed the presence of platinum on their surface (M6@PD, 0.54 mmol g-1 of Fe and M6@CA@DexPt1-2, 0.32-1.20 mmol g-1 of Fe); infrared spectroscopy (IR) and thermogravimetric and differential thermal analyses (TG-DTA) have confirmed the presence of dextran. Furthermore, the colloidal properties of these nanosystems (M6@PD and M6@CA@DexPt1-2) have been evaluated in water and in PBS buffer. Although M6@PD has shown good colloidal dispersion in water in the pH range of 2.0-8.0, the system underwent rapid agglomeration in PBS buffer. The M6@CA@DexPt1-2 nanosystems have exhibited improved colloidal behavior both in water and in PBS, where hydrodynamic sizes were kept below 100 nm over a large pH range (2.0-12.0). Furthermore, the latter systems have displayed isoelectric points below pH 5.0 and low surface charges at pH 7.0 (ζ-potential = -10 mV) and therefore PBS did not affect their colloidal stability.
Highlights
Superparamagnetic iron oxide nanoparticles (SPIONs) have been widely investigated for biomedical purposes.[1]
In this work we report the use of two new strategies (Scheme 1) to attach platinum complexes onto the surface of 6 nm superparamagnetic iron oxide nanoparticles (SPIONs) (M6): (i) by coating the SPIONs with platinum(II) complex functionalized dextran (DexPt1-2) and (ii) by direct coordination of a carboxylate platinum(IV) complex (PD) for comparison
Carboxymethyl-dextran sodium salt (CM-Dex), citric acid (CA, ≥ 99.5%), N-ethyl-N’-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC, ≥ 99%), ethylenediamine (EDA, ≥ 99%), hydrochloride acid (≥ 36%), hydrogen peroxide solution (30%), iron(II) chloride (≥ 99%), iron(III) nitrate (≥ 98%), nitric acid (≥ 65%), PBS buffer, potassium chloride (≥ 99%), potassium hydroxide (≥ 85%), potassium iodide (≥ 99%), potassium tetrachloroplatinate(II) (98%), silver nitrate (≥ 99%), succinic anhydride (≥ 99%) and all necessary solvents were purchased from Sigma-Aldrich
Summary
Superparamagnetic iron oxide nanoparticles (SPIONs) have been widely investigated for biomedical purposes.[1]. One of the key features for biomedical applications of SPIONs is their aqueous colloidal stability.[17] surface functionalization plays a relevant role on the balance of attractive forces, such as dispersion. In this work we report the use of two new strategies (Scheme 1) to attach platinum complexes onto the surface of 6 nm SPIONs (M6): (i) by coating the SPIONs with platinum(II) complex functionalized dextran (DexPt1-2) and (ii) by direct coordination of a carboxylate platinum(IV) complex (PD) for comparison. The colloidal properties of these nanosystems (M6@CA@DexPt1-2 and M6@PD) have been evaluated in aqueous and PBS buffer media. These studies are essential to comprehend their behavior, especially with respect to aggregation and surface charge, which will dictate their future applications
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