Yijing Liu

Self-Assembly of Amphiphilic Plasmonic Micelle-Like Nanoparticles in Selective Solvents

Amphiphilic plasmonic micelle-like nanoparticles (APMNs) composed of gold nanoparticles (AuNPs) and amphiphilic block copolymers (BCPs) structurally resemble polymer micelles with well-defined architectures and chemistry. The APMNs can be potentially considered as a prototype for modeling a higher-level self-assembly of micelles. The understanding of such secondary self-assembly is of particular importance for the bottom-up design of new hierarchical nanostructures. This article describes the self-assembly, modeling, and applications of APMN assemblies in selective solvents. In a mixture of water/tetrahydrofuran, APMNs assembled into various superstructures, including unimolecular micelles, clusters with controlled number of APMNs, and vesicles, depending on the lengths of polymer tethers and the sizes of AuNP cores. The delicate interplay of entropy and enthalpy contributions to the overall free energy associated with the assembly process, which is strongly dependent on the spherical architecture of APMNs, yields an assembly diagram that is different from the assembly of linear BCPs. Our experimental and computational studies suggested that the morphologies of assemblies were largely determined by the deformability of the effective nanoparticles (that is, nanoparticles together with tethered chains as a whole). The assemblies of APMNs resulted in strong absorption in near-infrared range due to the remarkable plasmonic coupling of Au cores, thus facilitating their biomedical applications in bioimaging and photothermal therapy of cancer.

Biomineralization-Inspired Synthesis of Copper Sulfide-Ferritin Nanocages as Cancer Theranostics.

It is essential to control the size and morphology of nanoparticles strictly in nanomedicine. Protein cages offer significant potential for templated synthesis of inorganic nanoparticles. In this study, we successfully synthesized ultrasmall copper sulfide (CuS) nanoparticles inside the cavity of ferritin (Fn) nanocages by a biomimetic synthesis method. The uniform CuS-Fn nanocages (CuS-Fn NCs) showed strong near-infrared absorbance and high photothermal conversion efficiency. In quantitative ratiometric photoacoustic imaging (PAI), the CuS-Fn NCs exhibited superior photoacoustic tomography improvements for real-time in vivo PAI of entire tumors. With the incorporation of radionuclide (64)Cu, (64)CuS-Fn NCs also served as an excellent PET imaging agent with higher tumor accumulation compared to free copper. Following the guidance of PAI and PET, CuS-Fn NCs were applied in photothermal therapy to achieve superior cancer therapeutic efficiency with good biocompatibility both in vitro and in vivo. The results demonstrate that the bioinspired multifunctional CuS-Fn NCs have potential as clinically translatable cancer theranostics and could provide a noninvasive, highly sensitive, and quantitative in vivo guiding method for cancer photothermal therapies in experimental and clinical settings.

Structure and negative thermal expansion in the PbTiO3–BiFeO3 system

The structures of (1−x)PbTiO3–xBiFeO3 (x=0.3 and 0.6) were investigated by means of the neutron powder diffraction. A splitting shift between Fe and Ti atoms was found along the c axis in 0.7PbTiO3–0.3BiFeO3; however, this splitting does not appear in 0.4PbTiO3–0.6BiFeO3. The tetragonal phase of PbTiO3–BiFeO3 exhibits a large spontaneous polarization. The negative thermal expansion of PbTiO3 is significantly enhanced in a wide temperature range by the BiFeO3 substitution. The average bulk thermal expansion coefficient of 0.4PbTiO3–0.6BiFeO3 is a¯v=−3.92×10−5°C−1, which is much strong in the known negative thermal expansion oxides.

Entropy-Driven Pattern Formation of Hybrid Vesicular Assemblies Made from Molecular and Nanoparticle Amphiphiles

Although an analogy has been drawn between them, organic molecular amphiphiles (MAMs) and inorganic nanoparticle (NP) amphiphiles (NPAMs) are significantly different in dimension, geometry, and composition as well as their assembly behavior. Their concurrent assembly can synergetically combine the inherent properties of both building blocks, thus leading to new hybrid materials with increasing complexity and functionality. Here we present a new strategy to fabricate hybrid vesicles with well-defined shape, morphology, and surface pattern by coassembling MAMs of block copolymers (BCPs) and NPAMs comprising inorganic NPs tethered with amphiphilic BCPs. The assembly of binary mixtures generated unique hybrid Janus-like vesicles with different shapes, patchy vesicles, and heterogeneous vesicles. Our experimental and computational studies indicate that the different nanostructures arise from the delicate interplay between the dimension mismatch of the two types of amphiphiles, the entanglement of polymer chains, and the mobility of NPAMs. In addition, the entropic attraction between NPAMs plays a dominant role in controlling the lateral phase separation of the two types of amphiphiles in the membranes. The ability to utilize multiple distinct amphiphiles to construct discrete assemblies represents a promising step in the self-assembly of structurally complex functional materials.

A general approach to synthesize asymmetric hybrid nanoparticles by interfacial reactions.

Asymmetric multicomponent nanoparticles (AMNPs) offer new opportunities for new-generation materials with improved or new synergetic properties not found in their individual components. There is, however, an urgent need for a synthetic strategy capable of preparing hybrid AMNPs with fine-tuned structural and compositional complexities. Herein, we report a new paradigm for the controllable synthesis of polymer/metal AMNPs with well-controlled size, shape, composition, and morphology by utilizing interfacial polymerization. The hybrid AMNPs display a new level of structural-architectural sophistication, such as controlled domain size and the number of each component of AMNPs. The approach is simple, versatile, cost-effective, and scalable for synthesizing large quantities of AMNPs. Our method may pave a new route to the design and synthesis of advanced breeds of building blocks for functional materials and devices.

Folding Up of Gold Nanoparticle Strings into Plasmonic Vesicles for Enhanced Photoacoustic Imaging

The stepwise self-assembly of hollow plasmonic vesicles with vesicular membranes containing strings of gold nanoparticles (NPs) is reported. The formation of chain vesicles can be controlled by tuning the density of the polymer ligands on the surface of the gold NPs. The strong absorption of the chain vesicles in the near-infrared (NIR) region leads to a much higher efficiency in photoacoustic (PA) imaging than for non-chain vesicles. The chain vesicles were further employed for the encapsulation of drugs and the NIR light triggered release of payloads. This work not only offers a new platform for controlling the hierarchical self-assembly of NPs, but also demonstrates that the physical properties of the materials can be tailored by controlling the spatial arrangement of NPs within assemblies to achieve a better performance in biomedical applications.

Glucose‐Responsive Sequential Generation of Hydrogen Peroxide and Nitric Oxide for Synergistic Cancer Starving‐Like/Gas Therapy

Glucose is a key energy supplier and nutrient for tumor growth. Herein, inspired by the glucose oxidase (GOx)-assisted conversion of glucose into gluconic acid and toxic H2 O2 , a novel treatment paradigm of starving-like therapy is developed for significant tumor-killing effects, more effective than conventional starving therapy by only cutting off the energy supply. Furthermore, the generated acidic H2 O2 can oxidize l-Arginine (l-Arg) into NO for enhanced gas therapy. By using hollow mesoporous organosilica nanoparticle (HMON) as a biocompatible/biodegradable nanocarrier for the co-delivery of GOx and l-Arg, a novel glucose-responsive nanomedicine (l-Arg-HMON-GOx) has been for the first time constructed for synergistic cancer starving-like/gas therapy without the need of external excitation, which yields a remarkable H2 O2 -NO cooperative anticancer effect with minimal adverse effect.

NIR‐Responsive On‐Demand Release of CO from Metal Carbonyl‐Caged Graphene Oxide Nanomedicine

On-demand release of carbon monoxide (CO) is realized through a novel near-infrared-responsive nanomedicine in favor of the enhancement of therapy efficacy and biosafety of CO therapy.

Wet‐Chemical Synthesis of Amphiphilic Rodlike Silica Particles and their Molecular Mimetic Assembly in Selective Solvents

Herein, we report a general strategy to design andsynthesize monodispersed amphiphilic silica rods (ASRs)with two segmented components by using a simple wet-chemical method. This template-free synthesis allows theindependent control over the aspect ratio of rods and thelength of each individual block. We also demonstrated themolecular mimetic self-assembly of ASRs into variousstructures including flower micelles, bundle micelles, starmicelles, planar monolayers, and reverse micelles in selectivesolvents. This self-assembly is solely determined by theproperties and volume fraction of the constituent blocks ofrods and the nature of solvents. The diverse morphologies ofthe self-assembled structures are a result of the dimension,shape,andrigidity oftheASRs, andsuchstructures cannotbeobtained from organic AMs.The synthetic strategy we developed for the preparationof ASRs was inspired by the recent work of Zhang et al. andKuijk et al.

Continuous Microfluidic Self-Assembly of Hybrid Janus-Like Vesicular Motors: Autonomous Propulsion and Controlled Release

A microfluidic strategy is developed for the continuous fabrication of hybrid Janus vesicular motors that uniquely combine the capability of autonomous propulsion and externally controlled delivery of encapsulated payload.