Surfactant-Assisted Cooperative Self-Assembly of Nanoparticles into Active Nanostructures

Abstract

Nanoparticles (NPs) of controlled size, shape, and composition are important building blocks for the next generation of devices. There are numerous recent examples of organizing uniformly sized NPs into ordered arrays or superstructures in processes such as solvent evaporation, heterogeneous solution assembly, Langmuir-Blodgett receptor-ligand interactions, and layer-by-layer assembly. This review summarizes recent progress in the development of surfactant-assisted cooperative self-assembly method using amphiphilic surfactants and NPs to synthesize new classes of highly ordered active nanostructures. Driven by cooperative interparticle interactions, surfactant-assisted NP nucleation and growth results in optically and electrically active nanomaterials with hierarchical structure and function. How the approach works with nanoscale materials of different dimensions into active nanostructures is discussed in details. Some applications of these self-assembled nanostructures in the areas of nanoelectronics, photocatalysis, and biomedicine are highlighted. Finally, we conclude with the current research progress and perspectives on the challenges and some future directions.

Keywords: Materials Science; Nanoparticles; Supramolecular Chemistry.

Graphical abstract

Figure 1

Schematic Illustration for the Surfactant-Assisted Cooperative Self-Assembly

Figure 2

Biocompatibility of QD-Micelles (A) An optical micrograph of CdSe QDs in chloroform and CdSe-micelles in water prepared using cetyl trimethylammonium bromide. (B) UV-vis spectra of (1) CdSe/CdS in hexane, (2) CdSe/CdS QD-micelles prepared using 1,2-dioctanoyl-sn-glycero-3-phosphocholine (C8-lipid) and hexadecylamine, and (3) 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-amino (polyethylene glycol) and dipalmitoyl phosphatidylcholine. (C) Transmission electron microscopic image of CdSe/CdS QD-micelles. (D) PL of CdSe/CdS in toluene (solid line) and C8-lipid-encapsulated CdSe/CdS QD-micelles in water (dashed line). Reprinted with permission from Fan et al. (Fan et al., 2005b). Copyright 2005 American Chemical Society.

Figure 3

Surfactant-Assisted Self-Assembly and Formation of 3D Superparticles (A) Schematic representation of the proposed formation mechanism of 3D self-assembly superparticles. (B) Transmission electron microscopic (TEM) image of oleic-acid-functionalized Fe₃O₄ nanocrystals. (C) DTAB-Fe₃O₄ nanocrystal micelles. (D) superparticles made without PVP. (E) superparticles capped with PVP. (F) An enlarged image of the inset in (E). (G) superparticles after annealing at 80°C for 6 h. Scale bars, 50 nm in (B and C) and 100 nm in (D–G). Reproduced with permission from Wang et al. (Wang et al., 2013a). Copyright 2013 of the Royal Society of Chemistry.

Figure 4

Emulsion-Confined Formation of 3D Superparticles Bai et al. demonstrated formation of BaCrO₄ superparticles by using anionic surfactant sodium dodecyl sulfate (SDS) to create an oil-in-water microemulsion by ultrasonic treatment (Bai et al., 2007). Typical sizes of the assembled BaCrO₄ superparticles are in the range of 100–120 nm. One important feature is that the constituent NPs retain their individual physical characteristics and do not sinter into larger particles. This is likely due to the fact that the self-assembly process relies on noncovalent interactions without chemical changes of the NPs. The surfactant bilayer surface has proved to be critical in stabilizing the superparticle. The zeta potential was measured to be a negative surface charge with potential of −27.6 mV, which is consistent with the use of SDS. In another example, when positive-charge surfactant CTAB is used to prepare Ag₂Se superparticles, zeta potential characterizations indicate that these colloidal sphere assemblies have a positive charge with potential of +38.0 mV.

Figure 5

Colloidal Superparticles Self-Assembled from Different NPs (A–E) (A) BaCrO₄, (B) Ag₂Se, (C) PbS, (D) ZrO₂, (E) NaYF₄. Reproduced with permission from Bai et al. (Bai et al., 2007). Copyright 2007 John Wiley & Sons, Inc. (F) TiO₂. Reproduced with permission from Lu et al., 2010. Copyright 2010 John Wiley & Sons, Inc. (G) CoFe₂O₄. Reproduced with permission from Nijs et al. (de Nijs et al., 2015). Copyright 2015 Macmillan Publishers Ltd. (H) Fe₃O₄ nanocubes. Reproduced with permission from Wang et al. (Wang et al., 2018a). Copyright 2018 Macmillan Publishers Ltd.

Figure 6

Temperature-Controlled Surfactant-Assisted Emulsion Self-Assembly (A) Schematic representations of the thermally controlled, emulsion-based bottom-up self-assembly process. (B–D) Low-magnification transmission electron microscopic (TEM) images of (B) an ordered superparticle exhibiting superlattice fringes of d(200) = 4.3 nm and d(111) = 4.9 nm, (C) a random superparticle, and (D) ordered arrays. (E–G) High-magnification TEM images showing the distance between two neighboring QDs in (E) ordered superparticles, (F) random superparticles, and (G) ordered arrays (scale bar, 1 nm). Reprinted with permission from Luo et al. (Luo et al., 2017). Copyright 2017 John Wiley & Sons, Inc.

Figure 7

Surfactant-Assisted Self-Assembly and Formation of Solid and Hollow Superparticles (A) Schematic description of iron oxide NP assemblies formed at two different temperatures. (B) Transmission electron microscopic (TEM) images of solid superparticles. (C) TEM images of hollow superparticles. Scale bars, 500 nm. Reproduced with permission from Park et al. (Park et al., 2016). Copyright 2016 John Wiley & Sons, Inc.

Figure 8

Multicomponent Superparticles Self-Assembled by Surfactant-Assisted Emulsion-Based Process (A) Schematic illustration of the self-assembly process to synthesize the Au/CdSe superparticles. (B and C) Transmission electron microscopic (B) and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) (C) images of Au/CdSe-0.15 superparticles (Au NPs size 7.2 nm) and corresponding energy dispersive spectroscopy (EDS) maps of Cd, Se, and Au. Inset in (B) shows the size distribution of as-prepared Au/CdSe superparticles. Scale bars, 50 nm in (C). Reprinted with permission from Shi et al. (Shi et al., 2017). Copyright 2017 John Wiley & Sons, Inc.

Figure 9

Formation of Nanorod Superparticles (A–C) (A) Transmission electron microscopic (TEM) overview of 3D double-domed cylindrical superparticles made from CdSe/CdS semiconductor nanorods, (B) TEM zoom, and (C) model of the double-domed superparticle microstructure. (D) Scanning electron microscopic overview of needle-like superparticles formed by CdSe/CdS semiconductor nanorods. (E and F) (E) TEM zoom and (F) model of the needle-like superparticle microstructure. Reproduced with permission from Wang et al. (Wang et al., 2012). Copyright 2012 AAAS.

Figure 10

Schematic Illustration of the Synthesis Processes of Porphyrin Nanocrystals by the Surfactant-Assisted Cooperative Self-Assembly Method Reprinted with permission from Zhong et al. (Zhong et al., 2014b). Copyright 2014 American Chemical Society.

Figure 11

Scanning and Transmission Electron Microscopic Images of the Porphyrin Nanocrystals with Different Shapes and Sizes (A–I) (A) Schematic illustration of formation of the self-assembled porphyrin nanostructures. (B) NPs, (C) nano-octahedra, (D) tetragonal nanorods, (E) hexagonal nanorods, (F) nanodisks, (G) hexagonal nanowires, (H) short nanowires, and (I) long nanowires. (A and D) Reproduced with permission from Zhong et al. (Zhong et al., 2014a). Copyright 2014 American Chemical Society. (B) Reproduced with permission from Wang et al. (Wang et al., 2018b). Copyright 2018 American Chemical Society. (C and G) Reproduced with permission from Wang et al. (Wang et al., 2016). Copyright 2016 American Chemical Society. (E and H) Reproduced with permission from Bai et al. (Bai et al., 2011). Copyright 2011 American Chemical Society. (F) Reproduced with permission from Bai et al. (Bai et al., 2010). Copyright 2010 of the Royal Society of Chemistry. (I) Reproduced with permission from Zhang et al. (Zhang et al., 2018). Copyright 2018 American Chemical Society.

Figure 12

Formation of Magnetic-Fluorescent Superparticles for Biological Applications (A) Schematic of the formation of the magnetic-fluorescent superparticles. (B–D) Transmission electron microscopic images of magnetic-fluorescent superparticles at different magnifications. Scale bars, 500 nm in (B), 100 nm in (C), and 10 nm in (D). (E) EDS elemental line scan result. Scale bar, 60 nm. (F) Intravital multiphoton microscopic picture of a HeLa cell in which magnetic-fluorescent superparticles have been microinjected. By bringing the magnetic tip in and out (blue bars), a reversible accumulation of magnetic-fluorescent superparticles (yellow region) can be created at the cell periphery (indicated by red dashed line) at different time points. Reproduced by permission from Chen et al. (Chen et al., 2014). Copyright 2014 Macmillan Publishers Ltd.

Figure 13

Formation of Core-Shell Structured ZnTPyP@SiO2 and Solid Mesophase ZnTPyP-SiO2 Nanocomposite Particles for PDT (A) Schematic diagram for the controlled formation of core-shell structured ZnTPyP@SiO2 and solid mesophase ZnTPyP-SiO2 nanocomposite particles. (B and C) Transmission electron microscopic images of the corresponding nanocomposite particles, respectively. (D and E) Relative viability of HeLa cells after treating with the corresponding nanocomposite particles, respectively. Reproduced with permission from Wang et al. (Wang et al., 2017). Copyright 2017 American Chemical Society.

Figure 14

Photocatalytic Hydrogen Production and Characterizations of the THPP Powders and Different Self-Assembled THPP Nanostructures (A) Hydrogen evolution photocatalyzed by THPP powders and different self-assembled nanostructures. (B) UV-vis spectra of different self-assembled THPP nanostructures. (C) XRD of different nanostructures. (D) Schematic illustration of the self-assembled J-aggregates and photo-induced charge process for hydrogen generation. Reprinted with permission from Zhang et al. (Zhang et al., 2018). Copyright 2018 American Chemical Society.

Figure 15

Charge Transport in Thin Film of Gold NP/Silica Arrays (A) I-V curves measured from 300 to 78 K. The inset shows a plot of the zero-bias conductance (G0) versus 1/T. The data exhibited Arrhenius behavior with activation energy (Ea) of ∼90 meV. (B) At T = 78 K, the current displayed a power-law dependence for V＞VT with scaling exponent ζ = 2.7 (negative bias) and ζ = 3.0 (positive bias). Reproduced with permission from Fan et al. (Fan et al., 2004). Copyright 2004 AAAS.