Silane-coated magnetic nanoparticles with surface thiol functions for conjugation with gold nanostars (original) (raw)
* Corresponding authors
a Dipartimento di Chimica, Università di Pavia, viale Taramelli, 12, 27100 Pavia, Italy
E-mail: piersandro.pallavicini@unipv.it
Fax: (+39) 0382 528 544
Tel: (+39) 0382 987 336
b King Abdullah University of Science and Technology (KAUST), Biological and Environmental Sciences and Egineering Division (BESE), 23955-6900 Thuwal, Kingdom of Saudi Arabia
c Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, UK
d Dipartimento di Chimica, Università di Parma, Parco Area delle Scienze, 17/A, 43124 Parma, Italy
Abstract
Small (d ∼ 8 nm) magnetite nanoparticles, Fe3O4NP, are prepared and coated with mercaptopropyl trimethoxysilane (MPTS) to form Fe3O4NP@MPTS. In the coating step controlled MPTS/Fe3O4NP molar ratios are used, ranging from 1 to 7.8 × 104. The total quantity of MPTS per Fe3O4NP is determined by SEM-EDS analysis and the average number of free, reactive –SH groups per Fe3O4NP is calculated by a colorimetric method. At very low molar ratios MPTS forms a submonolayer on the Fe3O4NP surface with all –SH free to react, while on increasing the MPTS/Fe3O4NP molar ratio the (CH3O)3Si– groups of MPTS polymerize, forming a progressively thicker shell, in which only a small fraction of the –SH groups, positioned on the shell surface, is available for further reaction. The MPTS shell reduces the magnetic interactions occurring between the magnetite cores, lowering the occurrence and strength of collective magnetic states, with Fe3O4NP@MPTS showing the typical behaviour expected for a sample with a mono-modal size distribution of superparamagnetic nanoparticles. Interaction of Fe3O4NP@MPTS with gold nanostars (GNS) was tested, using both Fe3O4NP@MPTS with a MPTS submonolayer and with increasing shell thickness. Provided that a good balance is used between the number of available –SH and the overall size of Fe3O4NP@MPTS, the free thiols of such nanoparticles bind GNS decorating their surface, as shown by UV-Vis spectroscopy and TEM imaging.
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Supplementary files
Article information
DOI
https://doi.org/10.1039/C5DT02812D
Article type
Paper
Submitted
23 Jul 2015
Accepted
10 Nov 2015
First published
10 Nov 2015
Download Citation
Dalton Trans., 2015,44, 21088-21098
Author version available
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Silane-coated magnetic nanoparticles with surface thiol functions for conjugation with gold nanostars
P. Pallavicini, E. Cabrini, A. Casu, G. Dacarro, Y. Antonio Diaz-Fernandez, A. Falqui, C. Milanese and F. Vita,Dalton Trans., 2015, 44, 21088DOI: 10.1039/C5DT02812D
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