Mediator−Template Assembly of Nanoparticles

Abstract

The ability to construct size- and shape-controllable architectures using nanoparticles as building blocks is essential for the exploration of nanoparticle-structured properties. This paper reports findings of an investigation of a mediator-template strategy for the size-controllable assembly of nanoparticles. This strategy explores multidentate thioether ligands as molecular mediators and tetraalkylammonium-capped gold nanoparticles (5 nm) as templates toward the preparation of size-controllable and monodispersed spherical assemblies ( approximately 20-300-nm diameters). The combination of the mediation force of the multidentate thioether and the hydrophobic force of the tetraalkylammonium template establishes the interparticle linkage and stability. The morphological properties of the spherical assemblies have been characterized using TEM, AFM, and SAXS techniques. The finding of the soft-hard nature of the nanoparticle assemblies and their interactions with contacting substrates could form the basis of a new strategy for manipulating nanoscale linkages between nanoparticle assemblies, soldering nanoelectronics, and constructing nanosensor devices. The intriguing light scattering and optical absorption properties in response to assembly, disassembly, sizing, and interparticle spacing parameters have been characterized by dynamic light scattering and spectrophotometric measurements. The discovery of the controlled disassembly into individual nanoparticles and the size regulation by a third capping component could form the basis for applications in controlled drug delivery. The fundamental basis for the mediator-template strategy as a versatile assembly technique is further discussed in terms of experimental and theoretical correlations of the morphological and optical properties.

Light-controlled self-assembly of reversible and irreversible nanoparticle suprastructures

“…Interestingly, this qualitative reasoning suggests that the coexistence curve between the two phases defined by ⌬G ϭ 0, should be a decreasing and concave function of N azo in the (N azo , x) plane, which agrees with the experimental phase diagram. We note briefly that, although spherical NP aggregates have been observed in other experimental systems (18,19), our light-induced supraspheres were significantly more stable because of crosslinking by ADTs, even to the extent that their outer surface could be further chemically derivatized, thus allowing their transfer to various other solvents (Fig. 3B).…”

Host–guest chemistry with water-soluble gold nanoparticle supraspheres

“…Although a variety of gold nanoparticle (Au NP) supraspheres have been prepared [14][15][16][17] , the hydrophobically driven formation of analogous assemblies in pure water remains elusive [18][19][20][21] . The main obstacle is that precipitation rapidly results from a lack of control over the aggregation processes 19 .…”

Detection of Oxidative Stress Biomarkers Using Novel Nanostructured Biosensors

“…Theoretical studies of plasmonic oscillations (Brioude et al, 2005, Draine et al, 1994, Gonzales et al, 2007, Jain et al, 2006, Kooij et al, 2006, Lee et al, 2005, 2006, Prescott et al, 2006, Ungureanu et al, 2009, Yang et al, 1995, Yin et al, 2006 and SP absorbance spectra (Alvarez et al, 1997, Etchegoin et al, 2006, Johnson et al, 1972, Kamat, 2002, Link et al, 1999a, Link et al, 1999b, Mishchenko et al, 2002, Perez-Juste et al, 2005, Ping et al, 2008 have enabled the understanding of mechanisms leading to the absorbance maximum shifts associated with the assembly processes. Extensive studies of the surface plasmon absorbance for various AuNP systems have been carried out by several groups (Alivisatos et al, 1996, Elghanian et al, 1997, Hostetler et al, 1998, Hostetler et al, 1999, Kamat, 2002, Kariuki et al, 2004, Kelly et al, 2003, Lim et al, 2009, Maye et al, 2005, Park et al, 2002, Reynolds et al, 2000, Storhoff et al, 1998, Taton et al, 2000, Taton et al, 2001, Zheng et al, 2000. In this work, the formation of networks of fluorosurfactant ZONYL-capped spherical AuNP's mediated by Hcys, and glutaraldehyde molecules have been investigated (Scheme 1).…”