Organizing inorganic nanocrystals into complex architectures is challenging and typically relies on preexisting templates, such as properly folded DNA or polypeptide chains. We found that under carefully controlled conditions, cubic nanocrystals of magnetite self-assemble into arrays of helical superstructures in a template-free manner with >99% yield. Computer simulations revealed that the formation of helices is determined by the interplay of van der Waals and magnetic dipole-dipole interactions, Zeeman coupling, and entropic forces and can be attributed to spontaneous formation of chiral nanocube clusters. Neighboring helices within their densely packed ensembles tended to adopt the same handedness in order to maximize packing, thus revealing a novel mechanism of symmetry breaking and chirality amplification.

Dual-responsive nanoparticles are designed by functionalizing magnetic cores with light-responsive ligands. These materials respond to both light and magnetic fields and can be assembled into various higher-order structures, depending on the relative contributions of these two stimuli.

Electrospinning from concentrated diphenylalanine solutions in a low‐boiling‐point solvent results in tubes that are chemically identical to self‐assembled tubes, but show different morphologies, especially extreme lengths. Electrospinning of tubes offers more possibilities for manipulation, for example, bridging electrodes in parallel orientation, a possible patterning strategy for electrospun material.

A novel single step method is developed for patterning multiple proteins within self‐assembled binary colloidal crystal patterns. Self‐assembly takes place by confining the suspensions in which either one or both types of particles are coated separately with proteins prior to mixing. This method offers precise control over the spacing between the proteins and the pattern size over large areas without any involvement of expensive lithographic techniques.

Surfaces with micro‐ and nanometer‐scale patterns have many potential applications, particularly in lifescience. This article reports on a versatile, straightforward, and inexpensive approach for the creation of chemical patterns using fabricated binary colloid crystals, consisting of small and large particles, as masks for the deposition of an amino‐functionalised ultrathin film by plasma polymerization. After removal of the binary colloidal mask, the characterization techniques [scanning electron microscopy (SEM) and atomic force microscopy (AFM)] reveal a surface contrast that depicts an ability of the small particles to allow diffusion of the plasma to the substrate. A plasma‐polymer film is created under the small particles and the region of substrate in direct contact with the large particle remains uncoated. Numerous types of patterns and feature heights can be produced with good fidelity over areas of several cm2 by appropriate tuning of the binary colloid crystal mask morphology and the plasma‐polymer deposition time. Finally, the amine groups of the patterned surface are used for covalent grafting poly(ethylene glycol) propionaldehyde (PEG‐PALD) by reductive amination under conditions of reduced solubility to produce a patterned surface for directed adsorption of protein. AFM investigations show that the proteins are preferentially attached to the nanometer‐scale regions of the pattern without PEG‐PALD.

Self-assembly of inorganic nanoparticles has been studied extensively for particles having different sizes and compositions. However, relatively little attention has been devoted to how the shape and surface chemistry of magnetic nanoparticles affects their self-assembly properties. Here, we undertook a combined experiment-theory study aimed at better understanding of the self-assembly of cubic magnetite (Fe3O4) particles. We demonstrated that, depending on the experimental parameters, such as the direction of the magnetic field and nanoparticle density, a variety of superstructures can be obtained, including one-dimensional filaments and helices, as well as C-shaped assemblies described here for the first time. Furthermore, we functionalized the surfaces of the magnetic nanocubes with light-sensitive ligands. Using these modified nanoparticles, we were able to achieve orthogonal control of self-assembly using a magnetic field and light.

Microbubbles (MBs) are routinely used as contrast agents for ultrasound imaging. The use of ultrasound in combination with MBs has also attracted attention as a method to enhance drug delivery.We have developed a technology platform incorporating multiple functionalities, including imaging and therapy in a single system consisting of MBs stabilized by polyethylene glycol (PEG) coated polymeric nanoparticles (NPs). The NPs, containing lipophilic drugs and/or contrast agents, are composed of the widely used poly(butyl cyanoacrylate) (PBCA) polymer and prepared in a single step. MBs stabilized by these NPs are subsequently prepared by self-assembly of NPs at the MB air/liquid interface. Here we show that these MBs can act as contrast agents for conventional ultrasound imaging. Successful encapsulation of iron oxide NPs inside the PBCA NPs is demonstrated, potentially enabling the NPs/MBs to be used as magnetic resonance imaging (MRI) and/or molecular ultrasound imaging contrast agents. By precise tuning of the applied ultrasound pulse, the MBs burst and the NPs constituting the shell are released. This could result in increased local deposit of NPs into target tissue providing improved therapy and imaging contrast compared to freely distributed NPs.

Carbon dots (CDs)-based nanoparticles have been extensively explored for biological applications in sensing and bioimaging. However, the major translational barriers to CDs for imaging and sensing applications include synthetic strategies to obtain monodisperse CDs with tunable structural, electronic, and optical properties in order to achieve high-resolution deep-tissue imaging, intracellular detection, and sensing of metal ions with high sensitivity down to nanomolar levels. Herein, we report a novel strategy to synthesize and develop a multifunctional nitrogen-doped CDs probe of different sizes using a new combination of carbon and nitrogen sources. Our results show that the structural characteristics (i.e., the surface density of emissive traps and bandgaps levels) depend on the size of the CDs, which ultimately influences their optical properties. This work also demonstrates the development of a two-photon dual-emissive fluorescent multifunctional probes (3-FCDs) by conjugating fluorescein isothiocyanate on the surface of nitrogen-doped CDs. 3-FCDs show excellent near-infrared two-photon excitation ability, single-wavelength excitation, high photostability, biocompatibility, low cytotoxicity, and good cell permeability. Using two-photon fluorescence imaging, our multifunctional probe shows excellent deep-tissue high-resolution imaging capabilities with penetration depth up to 3000 and 280 μm in hydrogel scaffold and pigskin tissue, respectively. The designed probe exhibits ultrasensitivity and specificity toward Fe3+ ions with a remarkable detection limit of 2.21 nM using two-photon excitation. In addition, we also demonstrate the use of multifunctional CDs probe for ultrasensitive exogenous and real-time endogenous sensing of Fe3+ ions and imaging in live fibroblasts with rapid response times for intracellular ferric ion detection.