Fabrication of gold nanoparticle-polymer composite particles with raspberry, core-shell and amorphous morphologies at room temperature via electrostatic interactions and diffusion

Gold Nanoparticle-Decorated Polymer Particles for High-Optical-Density Immunoassay Probes

To realize a highly sensitive immunoassay, high-optical-density probes conjugated with antibodies for target antigens are needed to increase the detectability of antigen-antibody complex formation. In this work, gold nanoparticle (NP)-decorated polymer (GNDP) particles were successfully prepared by mixing positively charged polymer particles and negatively charged Au NPs. GNDP particles decorated with NPs of 20 nm in size had higher optical density than the original Au NPs and GNDPs decorated with smaller Au NPs. Using GNDP particles as a probe, a highly sensitive immunoassay for influenza H1N1 hemagglutinin was realized with a minimum detectable concentration of 32.5 pg/mL. These results indicate that GNDP particles have high potential as an immunoassay probe that can be used in practical immunoassay systems for detecting a wide variety of antigens.

Universal Strategy for Inorganic Nanoparticle Incorporation into Mesoporous Liquid Crystal Polymer Particles

Developing inorganic-organic composite polymers necessitates a new strategy for effectively controlling shape and optical properties while accommodating guest materials, as conventional polymers primarily act as  carriers that transport inorganic substances. Here, a universal approach is introduced utilizing mesoporous liquid crystal polymer particles (MLPs) to fabricate inorganic-organic composites. By leveraging the liquid crystal phase, morphology and optical properties are precisely controlled through the molecular-level arrangement of the host, here monomers. The controlled host material allows the synthesis of inorganic particles within the matrix or accommodation of presynthesized nano-inorganic particles, all while preserving the intrinsic properties of the host material. This composite material surpasses the functional capabilities of the polymer alone by sequentially integrating one or more inorganic materials, allowing for the incorporation of multiple functionalities within a single polymer particle. Furthermore, this approach effectively mitigates the drawbacks associated with guest materials resulting in a substantial enhancement of composite performance. The presented approach is anticipated to hold immense potential for various applications in optoelectronics, catalysis, and biosensing, addressing the evolving demands of the society.

What is the role of PEO chains in the assembly of core-corona supraparticles in aqueous dispersions?

Hypothesis The assembly of core-corona supraparticles in aqueous dispersions has been regularly assisted by auxiliary monomers/oligomers which modify the individual particles with, e.g., surface grafting of polyethylene oxide (PEO) chains or other hydrophilic monomers. However, this modification complicates the preparation and purification procedures and increases potential upscaling efforts. Hybrid polymer-silica core-corona supracolloids could be more simply assembled if the PEO chains from surfactants, typically used by default as polymer stabilizers, concomitantly act as assembly promotors. The supracolloids assembly could therefore be more easily achieved without requiring particles functionalization or post-purification steps. Methods The self-assembly of supracolloidal particles prepared with PEO-surfactant stabilized (Triton X-405) and/or PEO-grafted polymer particles is compared to differentiate the roles of the PEO chains in the assembly of core-corona supraparticles. Using time-resolved dynamic light scattering (DLS) and cryogenic transmission electron microscopy(cryo-TEM), the effect of concentration of PEO chains (from surfactant) on the kinetics and dynamics of supracolloids assembly is investigated. Self-consistent field (SCF) lattice theory was used to numerically study the distribution of PEO chains at the interfaces present in the supracolloidal dispersions. Findings The PEO based surfactant can be used as assembly promoter of core-corona hybrid supracolloids due to its amphiphilic nature and via establishing hydrophobic interactions. The concentration of the PEO surfactant, and especially the PEO chains distribution over the different interfaces, crucially affect the supracolloids assembly. A simplified pathway for preparing hybrid supracolloidal particles with a well-controlled corona coverage over polymer cores is presented.

Environmental assessment of wastewater management via hybrid nanocomposite matrix implications-an organized review

Pollution of water is currently a significant worry for scientific communities all over the world, and it is imperative that this problem be solved as quickly as possible. It is today recognized to be one of the most important foci of research worldwide. The present dilemma of clean, fresh waste is being addressed by the subsequent ejection of impurities from polluted water following recycling. There are several effective solutions that have been promoted as a solution to this problem. Even if the present procedures for wastewater treatment degrade a wide variety of effluents efficiently, these protocols still have some kind of restrictions. The most cutting-edge research in this area is being done on the subject of nanotechnology, which has an astounding number of potential uses, one of which is the treatment of wastewater. One of the value-added alternatives utilized for water purification by eliminating the many types of pollutants found in wastewater is the green synthesis of nanocomposites in adsorbents, magnetic separation, photocatalysts, and other similar processes. Within the scope of this study, the most significant discoveries of nanocomposites to date that have been made towards the remediation of wastewater are highlighted.

From binary AB to ternary ABC supraparticles

Control over the assembly and morphology of nanoscale functional building blocks is of great importance to hybrid and porous nanomaterials. In this paper, by combining different types of spherical nanoparticles with different size ratios in a hierarchical assembly process which allows us to control the final structure of multi-component assemblies, we discuss self-assembly of an extensive range of supraparticles, labelled as AB particles, and an extension to novel ternary particles, labelled as ABC particles. For supraparticles, the organization of small nanoparticles is known to be inherently related to the size ratio of building blocks. Therefore, we studied the formation of supraparticles prepared by colloidal self-assembly using small silica nanoparticles (SiO₂ NPs) attached on the surface of large polystyrene latex nanoparticles (PSL NPs) with a wide size ratio range for complete and partial coverage, by controlling the electrostatic interactions between the organic and inorganic nanoparticles and their concentrations. In this way hierarchically ordered, stable supraparticles, either fully covered or partially covered, were realized. The partially covered, stable AB supraparticles offer the option to create ABC supraparticles of which the fully covered shell contains two different types of nanoparticles. This has been experimentally confirmed using iron oxide (Fe₃O₄) nanoparticles together with silica nanoparticles as shell particles on polystyrene core particles. Cryo-electron tomography was used to visualize the AB binary and ABC ternary supraparticles and to determine the three-dimensional structural characteristics of supraparticles formed under different conditions.

Biomacromolecular-Assembled Nanoclusters: Key Aspects for Robust Colloidal SERS Sensing

Superstructures of gold nanospheres offer augmented surface-enhanced Raman scattering (SERS) activities beyond the limits of their individual building blocks. However, for application as reliable and quantitative colloidal SERS probes, some key aspects need to be considered to combine efficiency and robustness with respect to hotspot excitation, analyte adsorption, signal stability, and colloidal stability. For this purpose, we studied core/satellite superstructures with spherical cores as a simple optically isotropic model system. Superstructures of different core sizes were assembled using bovine serum albumin (BSA), which serves as a non-specific biomacromolecular linker and provides electrosteric stabilization. We show that the "noisy" spectral footprint of the protein coating may serve as an internal standard, which allows accurate monitoring of the adsorption kinetics of analytes. The SERS activity was quantified using 4-mercaptobenzoic acid (MBA) as an aromatic low-molecular-weight model analyte. The molar SERS efficiency was studied by variation of the particle (Au⁰) and analyte concentrations with a limit of detection of 10^-7 M MBA. The practical importance of colloidal stability for robust measurement conditions was demonstrated by comparing the superstructures with their citrate-stabilized or protein-coated building blocks. We explain the theoretical background of hotspot formation by a leader/follower relationship of asymmetric control between the core and the satellites and give practical guidelines for robust colloidal SERS sensing probes.

Particle Surface Roughness as a Design Tool for Colloidal Systems

Control over the surface roughness of colloidal particles offers exciting opportunities to tailor the properties and the processing of a broad range of soft matter systems. Moreover, identifying surface roughness as a design parameter reveals the possibility to connect seemingly distinct phenomena and materials via the role played by roughness effects. In this feature article, we concisely review some approaches to synthesize and characterize rough colloidal particles, with a focus on model spherical colloids. We then discuss the impact that surface roughness has on both the high-shear rheology of dense suspensions and the stabilization of Pickering emulsions. Commenting on developments of our own research, we aim to offer an original perspective for a property-oriented development of colloidal particles that transcends classical divisions between materials and processes toward innovative solutions.

Synthetic strategies for raspberry-like polymer composite particles

The strategies used for the preparation of raspberry-like polymer composite particles are summarized comprehensively.

Irreversible photo-Fenton-like triggered agglomeration of ultra-small gold nanoparticles capped with crosslinkable materials

A photo-Fenton-like process can promote the agglomeration and LSPR red-shifting of ultra-small gold nanoparticles by triggering a crosslink-degradation pathway that involves the surface coating, Fe(iii)-citrate and hydrogen peroxide. Applications may range from controlled photo-deposition of active materials to asynchronous sensing technologies to light-focused microfabrication.

Microfluidic preparation of monodisperse polymeric microspheres coated with silica nanoparticles

The synthesis of organic-inorganic hybrid particles with highly controlled particle sizes in the micrometer range is a major challenge in many areas of research. Conventional methods are limited for nanometer-scale fabrication because of the difficulty in controlling the size. In this study, we present a microfluidic method for the preparation of organic-inorganic hybrid microparticles with poly (1,10-decanediol dimethacrylate-co-trimethoxysillyl propyl methacrylate) (P (DDMA-co-TPM)) as the core and silica nanoparticles as the shell. In this approach, the droplet-based microfluidic method combined with in situ photopolymerization produces highly monodisperse organic microparticles of P (DDMA-co-TPM) in a simple manner, and the silica nanoparticles gradually grow on the surface of the microparticles prepared via hydrolysis and condensation of tetraethoxysilane (TEOS) in a basic ammonium hydroxide medium without additional surface treatment. This approach leads to a reduction in the number of processes and allows drastically improved size uniformity compared to conventional methods. The morphology, composition, and structure of the hybrid microparticles are analyzed by SEM, TEM, FT-IR, EDS, and XPS, respectively. The results indicate the inorganic shell of the hybrid particles consists of SiO2 nanoparticles of approximately 60 nm. Finally, we experimentally describe the formation mechanism of a silica-coating layer on the organic surface of polymeric core particles.

Plasmono-magnetic material for precise photothermal heating

Noble metal nanoparticles have been extensively studied as photo-sensitive agents for photothermal cancer therapy. Precise control over the size and shape of the nanoparticles allowed strong optical absorption and efficient heat generation necessary for destroying a tumor to be achieved. However, one of the fundamental challenges of application of the nanoparticles towards photothermal cancer therapy is low specificity in the targeting tumor tissue in comparison with the healthy tissue and the resulting unfavorable biodistribution of the nanoparticles. Additional levels of control over particle distribution can be achieved by making the particles magnetic and using external magnets to control their accumulation in a tumor. Since the direct synthesis of particles with a magnetic core and a metallic shell limits the options for design and fine-tuning of plasmonic properties, the alternative approaches to the design of such materials have to be investigated. Here we propose and demonstrate a new design of a hybrid plasmono-magnetic material for photothermal heating created by grafting Au nanocages onto a surface of magnetic micro-beads. Next, we confirm its dual functionality in in vitro studies and show that individual hybrid particles can be magnetically controlled with a precision of a few micrometers and precisely destroy individual cells using plasmonic heating.

We demonstrated a new hybrid plasmono-magnetic material for photothermal heating created by grafting Au nanocages onto a surface of magnetic micro-beads.

pH Reversible Encapsulation of Oppositely Charged Colloids Mediated by Polyelectrolytes

We report the first example of reversible encapsulation of micron-sized particles by oppositely charged submicron smaller colloids. The reversibility of this encapsulation process is regulated by pH-responsive poly(acrylic acid) (PAA) present in solution. The competitive adsorption between the small colloids and the poly(acrylic acid) on the surface of the large colloids plays a key role in the encapsulation behavior of the system. pH offers an experimental knob to tune the electrostatic interactions between the two oppositely charged particle species via regulation of the charge density of the poly(acrylic acid). This results in an increased surface coverage of the large colloids by the smaller colloids when decreasing pH. Furthermore, the poly(acrylic acid) also acts as a steric barrier limiting the strength of the attractive forces between the oppositely charged particle species, thereby enabling detachment of the smaller colloids. Finally, based on the pH tunability of the encapsulation behavior and the ability of the small colloids to detach, reversible encapsulation is achieved by cycling pH in the presence of the PAA polyelectrolytes. The role of polyelectrolytes revealed in this work provides a new and facile strategy to control heteroaggregation behavior between oppositely charged colloids, paving the way to prepare sophisticated hierarchical assemblies.

Multibuilding Block Janus Synthesized by Seed-Mediated Self-Assembly for Enhanced Photothermal Effects and Colored Brownian Motion in an Optical Trap

The asymmetrical features and unique properties of multibuilding block Janus nanostructures (JNSs) provide superior functions for biomedical applications. However, their production process is very challenging. This problem has hampered the progress of JNS research and the exploration of their applications. In this study, an asymmetrical multibuilding block gold/iron oxide JNS has been generated to enhance photothermal effects and display colored Brownian motion in an optical trap. JNS is formed by seed-mediated self-assembly of nanoparticle-loaded thermocleavable micelles, where the hydrophobic backbones of the polymer are disrupted at high temperatures, resulting in secondary self-assembly and structural rearrangement. The JNS significantly enhances photothermal effects compared to their homogeneous counterpart after near-infrared (NIR) light irradiation. The asymmetrical distribution of gold and iron oxide within JNS also generates uneven thermophoretic force to display active colored Brownian rotational motion in a single-beam gradient optical trap. These properties indicate that the asymmetrical JNS could be employed as a strong photothermal therapy mediator and a fuel-free nanoscale Janus motor under NIR light.

In situ synthesis of the Ag/poly(4-vinylpyridine)-block-polystyrene composite nanoparticles by dispersion RAFT polymerization

A new method for the synthesis of metal/block-copolymer nanocomposites of poly(4-vinylpyridine)-b-polystyrene (P4VP-b-PS) and Ag nanoparticles by dispersion RAFT polymerization is proposed.

Synthesis of partially dextran-coated gold nanoworms and anisotropic structure based dual-strategic cargo conjugation for efficient combinational cancer therapy

Partially dextran-coated gold nanoworms enabled the dual-strategic conjugation of peptides and genes.

Self-assembly of poly(ionic liquid) (PIL)-based amphiphilic homopolymers into vesicles and supramolecular structures with dyes and silver nanoparticles

Self assembly of amphiphilic homo-PILs.

Polystyrene-Core-Silica-Shell Hybrid Particles Containing Gold and Magnetic Nanoparticles

Polystyrene-core-silica-shell hybrid particles were synthesized by combining the self-assembly of nanoparticles and the polymer with a silica coating strategy. The core-shell hybrid particles are composed of gold-nanoparticle-decorated polystyrene (PS-AuNP) colloids as the core and silica particles as the shell. PS-AuNP colloids were generated by the self-assembly of the PS-grafted AuNPs. The silica coating improved the thermal stability and dispersibility of the AuNPs. By removing the "free" PS of the core, hollow particles with a hydrophobic cage having a AuNP corona and an inert silica shell were obtained. Also, Fe3O4 nanoparticles were encapsulated in the core, which resulted in magnetic core-shell hybrid particles by the same strategy. These particles have potential applications in biomolecular separation and high-temperature catalysis and as nanoreactors.

Multifunctional and robust composite materials comprising gold nanoparticles at a spherical polystyrene particle surface

The preparation of composite particles comprising gold nanoparticles (4.5–26 nm) assembled at a polystyrene (PS) surface with tunable loading is reported with wide ranging potentials from cellular studies to catalysis.

Nanocomposites Based on Thermoplastic Polymers and Functional Nanofiller for Sensor Applications

Thermoplastic polymers like polyolefins, polyesters, polyamide, and styrene polymers are the most representative commodity plastics thanks to their cost-efficient manufacturing processes, excellent thermomechanical properties and their good environmental compatibility, including easy recycling. In the last few decades much effort has been devoted worldwide to extend the applications of such materials by conferring on them new properties through mixing and blending with different additives. In this latter context, nanocomposites have recently offered new exciting possibilities. This review discusses the successful use of nanostructured dispersed substrates in designing new stimuli-responsive nanocomposites; in particular, it provides an updated description of the synthetic routes to prepare nanostructured systems having the typical properties of thermoplastic polymers (continuous matrix), but showing enhanced optical, conductive, and thermal features dependent on the dispersion topology. The controlled nanodispersion of functional labeled clays, noble metal nanoparticles and carbon nanotubes is here evidenced to play a key role in producing hybrid thermoplastic materials that have been used in the design of devices, such as NLO devices, chemiresistors, temperature and deformation sensors.

Self-assembled nanoparticle micro-shells templated by liquid crystal sorting

A current goal in nanotechnology focuses on the assembly of different nanoparticle types into 3D organized structures. In this paper we report the use of a liquid crystal host phase in a new process for the generation of micron-scale vesicle-like nanoparticle shells stabilized by ligand-ligand interactions. The constructs formed consist of a robust, thin spherical layer, composed of closely packed quantum dots (QDs) and stabilized by local crystallization of the mesogenic ligands. Ligand structure can be tuned to vary QD packing within the shell and made UV cross-linkable to allow for intact shell extraction into toluene. The assembly method we describe could be extended to other nanoparticle types (metallic, magnetic etc.), where hollow shell formation is controlled by thermally sorting mesogen-functionalized nanoparticles in a liquid crystalline host material at the isotropic to nematic transition. This process represents a versatile method for making non-planar 3D nano-assemblies.

Fabrication of SERS-active conjugated copolymers/gold nanoparticles composite films by interface-directed assembly

A new composite film was synthesised by taking advantage of interface-directed assembly between thiol group-functionalized copolymers and Au NPs. The film not only exhibited strongly Au NP concentration-dependent SERS activity, but also allowed detection of a model molecule.

The assembly of polyethyleneimine-entrapped gold nanoparticles onto filter paper for catalytic applications

Polyethyleneimine-entrapped gold nanoparticles can be assembled onto filter paper via electrostatic interaction for high-performance catalytic applications.

Correction: Hood, M.A., et al. Synthetic Strategies in the Preparation of Polymer/Inorganic Hybrid Nanoparticles. Materials 2014, 7, 4057-4087

In [1], several sentences were repeated three times on pages 4062, 4063 and 4065. In addition, many references were incorrect. The errors were introduced by the editorial office during the editing process. We apologize for this mistake and any inconvenience this may have caused to authors and readers. The corrected manuscript is given below.[...].

In Situ Formation of Polymer-Gold Composite Nanoparticles with Tunable Morphologies

A simple and efficient route to gold-polymer nanoparticle composites is described. Our versatile synthetic route exerts facile control over polymer nanoparticle morphology, including micelles, rod-like structures, and vesicles, all easily attainable from a single polymerization taken to different monomer conversions. Specifically, poly[oligo(ethylene glycol) methacrylate]-b-poly(dimethylaminoethyl methacrylate)-b-poly(styrene) (POEGMA-b-PDMAEMA-b-PST) triblock copolymers were synthesized using a polymerization induced self-assembly (PISA) approach. Subsequently, spherical gold nanoparticles (10 nm AuNPs) were formed at the hydrophilic-hydrophobic nexus of the assembled triblock copolymer nanoaggregates by the addition of chloroauric acid (HAuCl₄) followed by in situ reduction using NaBH₄. After reduction, the cloudy white nanoparticle dispersions turned to a red-purple color. The gold nanoparticles that formed were stabilized by the enveloping polymeric nanostructures, neither precipitation nor agglomeration occurred. We demonstrated that we were able to tune the gold nanoparticle composition in these polymer-gold composites by varying the concentration of chloroauric acid. Morphology, particle size, molecular weight, AuNP content, and chemical structure of the polymer structures were characterized by transmittance electron microscopy (TEM), dynamic light scattering (DLS), size exclusion chromatography (SEC), thermal gravimetric analysis (TGA), and ¹H NMR. Finally, the formation of the AuNPs occurred without affecting the polymer nanoparticle morphology.

Synthetic Strategies in the Preparation of Polymer/Inorganic Hybrid Nanoparticles

This article reviews the recent advances and challenges in the preparation of polymer/inorganic hybrid nanoparticles. We mainly focus on synthetic strategies, basing our classification on whether the inorganic and the polymer components have been formed in situ or ex situ, of the hybrid material. Accordingly, four types of strategies are identified and described, referring to recent examples: (i) ex situ formation of the components and subsequent attachment or integration, either by covalent or noncovalent bonding; (ii) in situ polymerization in the presence of ex situ formed inorganic nanoparticles; (iii) in situ precipitation of the inorganic components on or in polymer structures; and (iv) strategies in which both polymer and inorganic component are simultaneously formed in situ.

A novel green synthesis approach for polymer nanocomposites decorated with silver nanoparticles and their antibacterial activity

A novel green synthesis strategy was developed for polymer composite spheres decorated with silver nanoparticles, mediated by a polymer colloid support itself, which are very stable and of high purity with excellent antibacterial activity.

Robust platforms for creating organic–inorganic nanocomposite microspheres: decorating polymer microspheres containing mussel-inspired adhesion layers with inorganic nanoparticles

A novel method for creating stable polymer microspheres decorated with inorganic nanoparticles using a mussel-inspired adhesive layer is reported.