Next Article in Journal
Effect of Defects on the Mechanical and Thermal Properties of Graphene
Previous Article in Journal
Antioxidant Bilayers Based on PHBV and Plasticized Electrospun PLA-PHB Fibers Encapsulating Catechin
Previous Article in Special Issue
Supramolecular Modification of ABC Triblock Terpolymers in Confinement Assembly
Open AccessArticle

Facile Strategy for the Synthesis of [email protected] Hybrid Nanoparticles with Controlled Porosity and Janus Morphology

1
School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, UK
2
Departamento de Química Física, Universidad Complutense de Madrid, Avenida Complutense s/n, 28040 Madrid, Spain
*
Authors to whom correspondence should be addressed.
Nanomaterials 2019, 9(3), 348; https://doi.org/10.3390/nano9030348
Received: 11 February 2019 / Revised: 22 February 2019 / Accepted: 26 February 2019 / Published: 3 March 2019
(This article belongs to the Special Issue Supramolecular Nano-architectures)
Hybrid materials prepared by encapsulation of plasmonic nanoparticles in porous silica systems are of increasing interest due to their high chemical stability and applications in optics, catalysis and biological sensing. Particularly promising is the possibility of obtaining [email protected] nanoparticles ([email protected]2 NPs) with Janus morphology, as the induced anisotropy can be further exploited to achieve selectivity and directionality in physical interactions and chemical reactivity. However, current methods to realise such systems rely on the use of complex procedures based on binary solvent mixtures and varying concentrations of precursors and reaction conditions, with reproducibility limited to specific [email protected]2 NP types. Here, we report a simple one-pot protocol leading to controlled crystallinity, pore order, monodispersity, and position of gold nanoparticles (AuNPs) within mesoporous silica by the simple addition of a small amount of sodium silicate. Using a fully water-based strategy and constant content of synthetic precursors, cetyl trimethylammonium bromide (CTAB) and tetraethyl orthosilicate (TEOS), we prepared a series of four silica systems: (A) without added silicate, (B) with added silicate, (C) with AuNPs and without added silicate, and (D) with AuNPs and with added silicate. The obtained samples were characterised by transmission electron microscopy (TEM), small angle X-ray scattering (SAXS), and UV-visible spectroscopy, and kinetic studies were carried out by monitoring the growth of the silica samples at different stages of the reaction: 1, 10, 15, 30 and 120 min. The analysis shows that the addition of sodium silicate in system B induces slower MCM-41 nanoparticle (MCM-41 NP) growth, with consequent higher crystallinity and better-defined hexagonal columnar porosity than those in system A. When the synthesis was carried out in the presence of CTAB-capped AuNPs, two different outcomes were obtained: without added silicate, isotropic mesoporous silica with AuNPs located at the centre and radial pore order (C), whereas the addition of silicate produced Janus-type [email protected]2 NPs (D) in the form of MCM-41 and AuNPs positioned at the silica–water interface. Our method was nicely reproducible with gold nanospheres of different sizes (10, 30, and 68 nm diameter) and gold nanorods (55 × 19 nm), proving to be the simplest and most versatile method to date for the realisation of Janus-type systems based on MCM-41-coated plasmonic nanoparticles. View Full-Text
Keywords: mesoporous silica; gold nanoparticles; Janus nanoparticles; sol–gel synthesis; MCM-41 mesoporous silica; gold nanoparticles; Janus nanoparticles; sol–gel synthesis; MCM-41
Show Figures

Graphical abstract

MDPI and ACS Style

Santana Vega, M.; Guerrero Martínez, A.; Cucinotta, F. Facile Strategy for the Synthesis of [email protected] Hybrid Nanoparticles with Controlled Porosity and Janus Morphology. Nanomaterials 2019, 9, 348.

Show more citation formats Show less citations formats
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

1
Search more from Scilit
 
Search
Back to TopTop