A one-pot method for building colloidal nanoparticles into bulk dry powders with nanoscale magnetic, plasmonic and catalytic functionalities

Abstract

Building easy-to-handle bulk materials with nanoproperties is crucial for many nanotechnology-based real-world applications. Here, we describe a simple onepot method based on nanoparticle self-assembly of pickering emulsions and in-situ polymer deposition for preparing particles consisting of a rigid micro-polymer core covered in exposed surface layers of nanoparticles, which we have named nanomicro-particles (NMPs). Unlike simple colloids, these NMPs can be filtered off from the aqueous suspensions in which they are prepared and dried to form free-flowing powders which, most importantly, retain the properties of the constituent nanoparticles in the surface layer. These NMPs can be stored for extended periods but then used either in the dry state or be re-suspended into liquid media as required. The preparation method is very general and can be readily extended to assemble various types of nanoparticles regardless of their material composition or morphology. In addition, functional components, such as magnetic particles or fluorescent tags, can be encapsulated within the polymer core. This method is a platform technology for building nanoparticles into bulk materials with nano-functionalities tailored towards real-life applications. This is illustrated with examples of the preparation of NMPs suitable for rapid and low-cost on-site water monitoring and remediation.

Self-assembly of colloidal nanoparticles into 2D arrays at water–oil interfaces: rational construction of stable SERS substrates with accessible enhancing surfaces and tailored plasmonic response

“…For example, evaporation of the oil core of plasmonically active emulsions produces spherical particle-aggregates which are stable and give very high SERS enhancements [81][82] while pre-doping the oil with polymer before evaporation yields SERS-active particles fixed onto a solid polymer core. [83][84]…”

Ultra‐Stable Plasmonic Colloidal Aggregates for Accurate and Reproducible Quantitative SE(R)RS in Protein‐Rich Biomedia

“…10 À7 m)ofamphiphilic "promoter" salts to provide counterions which sit in the oil phase allows charged NPs to assemble at oil-water liquidliquid interfaces by screening the interparticle electrostatic repulsion. [9] Here,the promoters are instead used to drive the NPs to the surface of the oil-in-water microemulsions. Figure 1a illustrates the process for the formation of SPAs using mono-disperse (25 AE 5nmdiameter) citrate-reduced Au colloid.…”

Dataset on constructing colloidal nanoparticles into dry nano-micro-particle (NMP) powders with Nanoscale Magnetic, Plasmonic and Catalytic Functionalities

“…SENSs are formed by fixing a monolayer 2D NP array assembled using promoters at the liquid-liquid interface (LLI) onto a thin polymer sheet in-situ through solvent evaporation. Therefore, SENSs have the same micro-structure as NMPs which makes them perfect candidates for contact angle measurements [1]. As shown in the contact angle data, citrate-capped NPs (θ = 75°) were notably more hydrophobic than PVP-capped NPs (θ = 38°) which generated stable Pickering emulsions.…”