Separation and purification of hydrophobic magnetite-gold hybrid nanoparticles by multiphase density gradient centrifugation

Abstract

The authors describe a multiphase density gradient centrifugation method for the separation and purification of hybrid nanoparticles (NPs). The method was applied to the purification of NPs consisting of magnetite gold NPs of type Fe 3 O 4 @Au and coated with 1-dodecylthiol. A density gradient has been established by forming cushions of a multicomponent solution composed of (a) a nonlinear gradient of sucrose in the of 5-50 % concentration range, (b) a constant concentration of ficoll (a neutral, highly branched, high-mass, hydrophilic polysaccharide; 30 % w/w), and (c) a constant concentration of percoll (colloidal silica particles coated with polyvinylpyrrolidone; 15 % w/w). The final separation profiles are adjusted via dynamic differential centrifugation at 4480×g for 30 min. The mixture of NPs to be separated is added and centrifuged at 2520×g for 40 min. This will separate the NPs into five fractions together with other secondary components. The fractions were characterized by FTIR, XPS, and SEM-EDX techniques. Finally, a continuous flow system with resonance light scattering detection was established and coupled to the separation system in order to monitor the separated fractions.

Usefulness of Hybrid Magnetoliposomes for Aminoglycoside Antibiotic Residues Determination in Food Using an Integrated Microfluidic System with Fluorometric Detection

“…The variables affecting the synthesis of h-MLs containing Fe 3 O 4 @AuNPs-C12SH and NAC were studied using the univariate method. Fe 3 O 4 @AuNPs-C12SH were prepared using a previously described method. , The use of magnetic NPs coated with AuNPs allows the hydrophobicity of their surface by modification with C12SH, required to increase their encapsulation efficiency in the lipid bilayer of liposomes. The characterization of these NPs has been widely studied. , TEM images showed spherical structures with an average diameter of 30 ± 10 nm.…”

“…Fe 3 O 4 @AuNPs-C12SH were prepared using a previously described method. , The use of magnetic NPs coated with AuNPs allows the hydrophobicity of their surface by modification with C12SH, required to increase their encapsulation efficiency in the lipid bilayer of liposomes. The characterization of these NPs has been widely studied. , TEM images showed spherical structures with an average diameter of 30 ± 10 nm. Their morphology and elemental composition were studied by infrared (FTIR), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy equipped with an energy dispersive detector (SEM-EDX).…”

“…Fe 3 O 4 @AuNPs-C12SH were prepared using a previously described method. 7,27 The use of magnetic NPs coated with AuNPs allows the hydrophobicity of their surface by modification with C12SH, required to increase their encapsulation efficiency in the lipid bilayer of liposomes. The characterization of these NPs has been widely studied.…”

“…The synthesis of h-MLs involved incorporating hydrophobic magnetic gold nanoparticles (Fe3O4@AuNPs-C12SH) to retain them in the reaction/detection zone magnetically and encapsulation of NAC to obtain the analytical signal. The NAC encapsulation in liposomes has been demonstrated previously. − Fe 3 O 4 @AuNPs-C12SH were obtained using a previously described procedure, in which the synthesis of Fe 3 O 4 NPs by the coprecipitation method was performed first, and then they were coated with gold nanoparticles with C12SH at their surface . Briefly, 25 mL of an 0.4 mol L –1 iron­(III) chloride, 0.4 mol L –1 iron­(II) chloride, and 40 mmol L –1 hydrochloric acid aqueous solution was added dropwise under vigorous stirring into 250 mL of a 1.5 mol L –1 sodium hydroxide solution.…”

“…24−26 Fe 3 O 4 @AuNPs-C12SH were obtained using a previously described procedure, in which the synthesis of Fe 3 O 4 NPs by the coprecipitation method was performed first, and then they were coated with gold nanoparticles with C12SH at their surface. 27 Briefly, 25 mL of an 0.4 mol L −1 iron(III) chloride, 0.4 mol L −1 iron(II) chloride, and 40 mmol L −1 hydrochloric acid aqueous solution was added dropwise under vigorous stirring into 250 mL of a 1.5 mol L −1 sodium hydroxide solution. Black-brown Fe 3 O 4 NPs were immediately formed, separated using a commercial NdFeB magnet, and washed three times with deionized water.…”