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Investigates the properties of thin films of a number of simple liquids using surface force balance capable of simultaneous shear and normal measurements. Solidification of films due to confinement; Characterization of the sliding of the confining surfaces at mean velocity; Introduction of a simple model for friction; Characteristics of stick-slip.

Describes a surface force balance with extremely high sensitivity and resolution in measuring shear forces across thin films. Properties of confined simple liquids; Effect on the simple liquid process of the investigation; Transition in the liquidlike behavior and solidlike phase under progressive confinement.

The article focuses on multicellular cancer spheroids in vitro model that replicates many features of solid tumors in vivo. It mentions that biomimetic hydrogel scaffolds for MCS growth recapitulate the behavior of natural extracellular matrix, essential for regulating cancer cell behavior. It further review the use of different types of hydrogels for MCS growth.

Nanocolloidal gels (NCGs) are an emerging class of soft matter, in which nanoparticles act as building blocks of the colloidal network. Chemical or physical crosslinking enables NCG synthesis and assembly from a broad range of nanoparticles, polymers, and low-molecular weight molecules. The synergistic properties of NCGs are governed by nanoparticle composition, dimensions and shape, the mechanism of nanoparticle bonding, and the NCG architecture, as well as the nature of molecular crosslinkers. Nanocolloidal gels find applications in soft robotics, bioengineering, optically active coatings and sensors, optoelectronic devices, and absorbents. This review summarizes currently scattered aspects of NCG formation, properties, characterization, and applications. We describe the diversity of NCG building blocks, discuss the mechanisms of NCG formation, review characterization techniques, outline NCG fabrication and processing methods, and highlight most common NCG applications. The review is concluded with the discussion of perspectives in the design and development of NCGs. [ABSTRACT FROM AUTHOR]

Adsorption of polymer molecules under flow conditions governs a broad range of desired or undesired phenomena and has a broad range of applications. Microfluidic platforms integrated with analytical instrumentation offer the capability to study polymer adsorption in flow in a time- and labour-efficient manner. Precise control of the microchannel dimensions and flow parameters enables accurate control of shear forces imposed on polymer solutions and on the molecules deposited on the surface, along with high sensitivity, enhanced reliability, and low reagent consumption. This review highlights recent advances in theoretical and experimental microfluidic studies of polymer immobilization under flow conditions in three area, namely, biosensing, biofouling, and studies of thrombosis and hemostasis. [ABSTRACT FROM AUTHOR]

We review recent progress in the development of polymer nanostructured materials with periodic structures and compositions having applications in photonics and optical data storage. This review provides a brief description of the microfabrication and self-assembly methods used for the production of polymer materials with periodic structures, and highlights the properties and applications of photonic materials derived from block copolymers, colloid crystals, and microfabricated polymers. We conclude with a summary of current and future research efforts and opportunities in the development of polymer materials for photonic applications. [Copyright &y& Elsevier]

The ability to pattern functional polymers at different length scales is important for research fields including cell biology, tissue engineering and medicinal science and the development of optics and electronics. The interest and capabilities of polymer patterning have originated from the abundance of functionalities of polymers and a wide range of applications of the patterns. This paper reviews recent advances in top-down and bottom-up patterning of polymers using photolithography, printing techniques, self-assembly of block copolymers and instability-induced patterning. Finally, challenges and future directions are discussed from the point of view of both applicability and strategies for the surface patterning of polymers. [ABSTRACT FROM AUTHOR]

We report colloid crystal growth by using electrodeposition of charged polymer colloid particles on patterned conductive substrates. We used photolithography to create patterns with conductive grooves and dielectric ribs on indium-tin oxide surfaces. Two approaches were used to enhance long-range order in two-dimensional colloid crystals grown on patterned surfaces: (i) patterning of substrates with features commensurate with several particle diameters and (ii) patterning of substrates with features commensurate with a single particle diameter. We demonstrate the effect of commensurability on colloid crystal growth and present the results of real-time studies of colloid crystallization in constrained geometry during electrodeposition on patterned substrates. [ABSTRACT FROM AUTHOR]

Studies the liquid-to-solid transition of a simple model liquid confined between two surfaces as a function of surface separation. Decrease of separation corresponding to seven molecular layers; Display of liquid-like shear viscosity; Transition to a solid.

Focuses the reduction in the effective frictional forces between solid surfaces bearing polymer brushes. Use of lubricants to reduce friction and wear between rubbing surfaces; Tethering polymer chains to the surfaces; Profiles measured between mica surfaces; Long-ranged repulsion between the brushes.

Fibrous networks formed by biological polymers such as collagen or fibrin exhibit nonlinear mechanical behavior. They undergo strong stiffening in response to weak shear and elongational strains, but soften under compressional strain, in striking difference with the response to the deformation of flexible-strand networks formed by molecules. The nonlinear properties of fibrous networks are attributed to the mechanical asymmetry of the constituent filaments, for which a stretching modulus is significantly larger than the bending modulus. Studies of the nonlinear mechanical behavior are generally performed on hydrogels formed by biological polymers, which offers limited control over network architecture. Here, we report an engineered covalently cross-linked nanofibrillar hydrogel derived from cellulose nanocrystals and gelatin. The variation in hydrogel com)position provided a broad-range change in its shear modulus. The hydrogel exhibited both shear-stiffening and compression-induced softening, in agreement with the predictions of the affine model. The threshold nonlinear stress and strain were universal for the hydrogels with different compositions, which suggested that nonlinear mechanical properties are general for networks formed by rigid filaments. The experimental results were in agreement with an affine model describing deformation of the network formed by rigid filaments. Our results lend insight into the structural features that govern the nonlinear biomechanics of fibrous networks and provide a platform for future studies of the biological impact of nonlinear mechanical properties. [ABSTRACT FROM AUTHOR]

Using a computational model, we investigate the motion of microcapsules inside a microchannel that encompasses a narrow constriction. The microcapsules are composed of a compliant, elastic shell and an encapsulated fluid; these fluid-filled shells model synthetic polymeric microcapsules or biological cells (e.g., leukocytes). Driven by an imposed flow, the capsules are propelled along the microchannel and through the constricted region, which is formed by two pillars that lie in registry, extending from the top and bottom walls of the channels. The tops of these pillars (facing into the microchannel) are modified to exhibit either a neutral or an attractive interaction with the microcapsules. The pillars (and constriction) model topological features that can be introduced into microfluidic devices or the physical and chemical heterogeneities that are inherently present in biological vessels. To simulate the behavior of this complex system, we employ a hybrid method that integrates the lattice Boltzmann model (LBM) for fluid dynamics and the lattice spring model (LSM) for the micromechanics of elastic solids. Through this LBM/LSM technique, we probe how the capsule’s stiffness and interaction with the pillars affect its passage through the chambers. The results yield guidelines for regulating the movement of microcarriers in microfluidic systems and provide insight into the flow properties of biological cells in capillaries. [ABSTRACT FROM AUTHOR]

The unique properties of a polymer photonic crystal are examined with respect to applications as a medium for high-density three-dimensional optical data storage media. The nanocomposite material was produced from core-shell latex particles, in which the latex cores contained dye-labeled polymer. Nonfluorescent latex shells were attached to the core particles. Upon annealing, the close-packed core-shell particles formed a nanostructured material with the fluorescent particles periodically embedded into the optically inert matrix in a hexagonal close-packed structure. A two-photon laser scanning microscope was used to write bits of information into the material by photobleaching the optically sensitive particles and, under much lower fluence, read out the resulting image. Relative to conventional homogeneous storage media, the nanostructured periodic material is shown to increase the effective optical storage density by at least a factor of 2 by spatially localizing the optically active region and imposing an optically inactive barrier to cross-talk between bits. This polymer photonic crystal has the potential to dramatically improve performance further through the improved capabilities to optimize the photochemical processes and more fully exploiting the periodic nature of the information domains in the image processing. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The article discuses the physiological properties of hydro gels. It informs that polymer hydrogen system displays homeostatic and self-regulatory behavior similar to those found in living systems by encompassing chemical, thermal and mechanical responses in a reversible manner. It also presents information on self-oscillating gels which has shown potential application in drug delivery.

Using two orthogonal external stimuli, programmable staged surface patterning and self‐assembly of inorganic nanoparticles (NPs) was achieved. For gold NPs capped with end‐grafted poly(styrene‐block‐(4‐vinylbenzoic acid)), P(St‐block‐4VBA), block copolymer ligands, surface‐pinned micelles (patches) formed from NP‐adjacent PSt blocks under reduced solvency conditions (Stimulus 1); solvated NP‐remote P(4VBA) blocks stabilized the NPs against aggregation. Subsequent self‐assembly of patchy NPs was triggered by crosslinking the P(4VBA) blocks with copper(II) ions (Stimulus 2). Block copolymer ligand design has a strong effect on NP self‐assembly. Small, well‐defined clusters assembled from NPs functionalized with ligands with a short P(4VBA) block, while NPs tethered with ligands with a long P(4VBA) block formed large irregularly shaped assemblies. This approach is promising for high‐yield fabrication of colloidal molecules and their assemblies with structural and functional complexity. [ABSTRACT FROM AUTHOR]

Using two orthogonal external stimuli, programmable staged surface patterning and self‐assembly of inorganic nanoparticles (NPs) was achieved. For gold NPs capped with end‐grafted poly(styrene‐block‐(4‐vinylbenzoic acid)), P(St‐block‐4VBA), block copolymer ligands, surface‐pinned micelles (patches) formed from NP‐adjacent PSt blocks under reduced solvency conditions (Stimulus 1); solvated NP‐remote P(4VBA) blocks stabilized the NPs against aggregation. Subsequent self‐assembly of patchy NPs was triggered by crosslinking the P(4VBA) blocks with copper(II) ions (Stimulus 2). Block copolymer ligand design has a strong effect on NP self‐assembly. Small, well‐defined clusters assembled from NPs functionalized with ligands with a short P(4VBA) block, while NPs tethered with ligands with a long P(4VBA) block formed large irregularly shaped assemblies. This approach is promising for high‐yield fabrication of colloidal molecules and their assemblies with structural and functional complexity. [ABSTRACT FROM AUTHOR]

Using two orthogonal external stimuli, programmable staged surface patterning and self‐assembly of inorganic nanoparticles (NPs) was achieved. For gold NPs capped with end‐grafted poly(styrene‐block‐(4‐vinylbenzoic acid)), P(St‐block‐4VBA), block copolymer ligands, surface‐pinned micelles (patches) formed from NP‐adjacent PSt blocks under reduced solvency conditions (Stimulus 1); solvated NP‐remote P(4VBA) blocks stabilized the NPs against aggregation. Subsequent self‐assembly of patchy NPs was triggered by crosslinking the P(4VBA) blocks with copper(II) ions (Stimulus 2). Block copolymer ligand design has a strong effect on NP self‐assembly. Small, well‐defined clusters assembled from NPs functionalized with ligands with a short P(4VBA) block, while NPs tethered with ligands with a long P(4VBA) block formed large irregularly shaped assemblies. This approach is promising for high‐yield fabrication of colloidal molecules and their assemblies with structural and functional complexity. [ABSTRACT FROM AUTHOR]

Focuses on the production of morphologies in polymeric films. Replication of convection patterns; Difference of temperature across the liquid film; Replacement of monomers with polymeric fluids.

Intelligent packaging and point-of-use devices designed to monitor food quality and package integrity, as well as assist in food authentication, are currently unaffordable to the food industry due to costly conventional fabrication methods, namely inkjet printing, gravure printing, and screen-printing technologies. Another major hindrance is the availability and use of safe food-friendly materials to produce the smart components (i.e., sensors, indicators, and tags) that monitor these parameters. Recently, however, additive manufacturing (stereolithography and extrusion-based 3D printing) has emerged as a cost-effective solution for the fabrication of these smart systems from materials deemed safe and food-friendly by internationally recognised food regulation agencies. This study emphasises the importance of utilizing intelligent food packaging. Regular food packaging allows potential tampering, contamination, and food fraud to go undetected. Intelligent food packaging, however, allows for real-time communication on the state of a food product and would assist in food defense and ensure consumers receive food products of the highest quality. Unfortunately, consumers are currently unwilling to shoulder the costs associated with intelligent food packaging and point-of-use devices fabricated using conventional approaches. This review explores 3D printing as a viable alternative. A 3D printing approach to the fabrication of intelligent packaging and point-of-use devices allows for the development of highly sensitive, self-indicating, multifunctional smart components using biocompatible nontoxic materials more cheaply than conventional fabrication methods. This would make intelligent food packaging more ubiquitous and, in turn, reduce food waste and prevent consumers from ingesting unfit food products. [Display omitted] • Monitoring food quality, safety, and identity. • Affordable fabrication of intelligent food packaging. • 3D printing utilizes nontoxic biocompatible materials that are food-safe. • Sensitive multifunctional smart components\. [ABSTRACT FROM AUTHOR]

Metal nanoparticles (NPs) stabilized with thiol‐ (HS‐) terminated polymers have applications in medicine, optoelectronics, and catalysis. It is assumed that upon exposure to oxidants or even air, these NPs lose colloidal stability, due to the oxidation of the HS‐end‐group and elimination of polymer ligands from the NP surface, however, this mechanism does not explain the unsuccessful recovery of the NP stability by adding fresh HS‐terminated polymers. Here we propose the oxidation of the surface metal atoms as a mechanism for the oxidative elimination of polymer from the NP surface. Based on this mechanism, we reversed NP aggregation by reducing the oxidized metal surface and re‐attaching HS‐terminated polymer ligands. This mechanism is general for various metal NPs and different HS‐terminated polymers. We show that oxidative elimination and reductive addition reactions can improve the colloidal stability of polymer‐capped metal NPs and control their redox stimuli‐responsive self‐assembly. [ABSTRACT FROM AUTHOR]

Metal nanoparticles (NPs) stabilized with thiol‐ (HS‐) terminated polymers have applications in medicine, optoelectronics, and catalysis. It is assumed that upon exposure to oxidants or even air, these NPs lose colloidal stability, due to the oxidation of the HS‐end‐group and elimination of polymer ligands from the NP surface, however, this mechanism does not explain the unsuccessful recovery of the NP stability by adding fresh HS‐terminated polymers. Here we propose the oxidation of the surface metal atoms as a mechanism for the oxidative elimination of polymer from the NP surface. Based on this mechanism, we reversed NP aggregation by reducing the oxidized metal surface and re‐attaching HS‐terminated polymer ligands. This mechanism is general for various metal NPs and different HS‐terminated polymers. We show that oxidative elimination and reductive addition reactions can improve the colloidal stability of polymer‐capped metal NPs and control their redox stimuli‐responsive self‐assembly. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO2) sequestration, storage and recycling will greatly benefit from comprehensive studies of physical and chemical gas-liquid processes involving CO2. Over the past five years, microfluidics emerged as a valuable tool in CO2-related research, due to superior mass and heat transfer, reduced axial dispersion, well-defined gas-liquid interfacial areas and the ability to vary reagent concentrations in a high-throughput manner. This Minireview highlights recent progress in microfluidic studies of CO2-related processes, including dissolution of CO2 in physical solvents, CO2 reactions, the utilization of CO2 in materials science, and the use of supercritical CO2 as a "green" solvent. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO2) sequestration, storage and recycling will greatly benefit from comprehensive studies of physical and chemical gas-liquid processes involving CO2. Over the past five years, microfluidics emerged as a valuable tool in CO2-related research, due to superior mass and heat transfer, reduced axial dispersion, well-defined gas-liquid interfacial areas and the ability to vary reagent concentrations in a high-throughput manner. This Minireview highlights recent progress in microfluidic studies of CO2-related processes, including dissolution of CO2 in physical solvents, CO2 reactions, the utilization of CO2 in materials science, and the use of supercritical CO2 as a "green" solvent. [ABSTRACT FROM AUTHOR]

Self-assembly of plasmonic nanoparticles offers a labour- and cost-efficient strategy for the expansion of the library of plasmonic nanostructures with highly tunable, coupled optical properties. This review covers recent advances in solution-based self-assembly of plasmonic nanoparticles, modelling of the self-assembly process and of the optical properties of the resulting nanostructures, and potential applications of self-assembled plasmonic nanostructures. [ABSTRACT FROM AUTHOR]

Nanocolloidal gels are emerging as a promising class of materials with applications as inks in 2D and 3D printing. Polymer nanoparticles (NPs) offer many advantages as potential building blocks of nanocolloidal gels, due to the ability to control NP dimensions, charge, surface chemistry, and functionality; however, their applications as inks in printing are yet to be explored. Here, functional nanocolloidal hydrogels formed by percolating oppositely charged latex NPs with different dimensions and charge densities are reported. The shear‐thinning and self‐healing properties of the nanocolloidal gels and the mechanical properties of the resulting printed films are examined. NP functionality is achieved by covalently labeling them with different fluorescent dyes that emit at two distinct wavelengths. Using these NPs, a facile route for 3D printing of multicolored fluorescence patterns is shown, with each color being visualized under a specific, well‐defined excitation wavelength. [ABSTRACT FROM AUTHOR]

Many applications of inorganic nanoparticles (NPs), including photocatalysis, photovoltaics, chemical and biochemical sensing, and theranostics, are governed by NP optical properties. Exploration and identification of reaction conditions for the synthesis of NPs with targeted spectroscopic characteristics is a time‐, labor‐, and resource‐intensive task, as it involves the optimization of multiple interdependent reaction conditions. Integration of machine learning (ML) and microfluidics (MF) offers accelerated identification and optimization of reaction conditions for NP synthesis. Here, an autonomous ML‐driven, oscillatory MF platform for the synthesis of NPs is reported. The platform utilized multiple recipes and reaction times for the synthesis of NPs with different dimensions, conducted spectroscopic NP characterization, and employed ML approaches to analyze multiple yet prioritized spectroscopic NP characteristics, and identified reaction conditions for the synthesis of NPs with targeted optical properties. The platform is also used to develop an understanding of the relationship between reaction conditions and NP properties. This study shows the strong potential of ML‐driven oscillatory MF platforms in materials science and paves the way for automated NP development. [ABSTRACT FROM AUTHOR]

Generation of nanostructures containing from several to thousands of inorganic nanorods (NRs) organized in a highly ordered manner paves the way for applications that exploit directional properties of NR arrays. Self-assembly of NRs provides a simple and cost-efficient strategy for producing NR ensembles. This tutorial review highlights recent advances in the field of NR synthesis, summarizes the types of ligands used for NR synthesis and stabilization, reviews experimental and theoretical work on NRself-assembly that is driven by interactions between the ligands and describes current properties and applications of self-assembled NR structures. [ABSTRACT FROM AUTHOR]

Generation of nanostructures containing from several to thousands of inorganic nanorods (NRs) organized in a highly ordered manner paves the way for applications that exploit directional properties of NR arrays. Self-assembly of NRs provides a simple and cost-efficient strategy for producing NR ensembles. This tutorial reviewhighlights recent advances in the field of NR synthesis, summarizes the types of ligands used for NR synthesis and stabilization, reviews experimental and theoretical work on NR self-assembly that is driven by interactions between the ligands and describes current properties and applications of self-assembled NR structures. [ABSTRACT FROM AUTHOR]

Just as nanoparticles display properties that differ from those of bulk samples of the same material, ensembles of nanoparticles can have collective properties that are different to those displayed by individual nanoparticles and bulk samples. Self-assembly has emerged as a powerful technique for controlling the structure and properties of ensembles of inorganic nanoparticles. Here we review different strategies for nanoparticle self-assembly, the properties of self-assembled structures of nanoparticles, and potential applications of such structures. Many of these properties and possible applications rely on our ability to control the interactions between the electronic, magnetic and optical properties of the individual nanoparticles. [ABSTRACT FROM AUTHOR]

Organized arrays of anisotropic nanoparticles show electronic and optical properties that originate from the coupling of shape-dependent properties of the individual nanorods. The organization of nanorods in a controllable and predictable way provides a route to the fabrication of new materials and functional devices. So far, significant progress has been achieved in the self-assembly of nanorod arrays, yet the realization of a range of different structures requires changing the surface chemistry of the nanoparticles. We organized metal nanorods in structures with varying geometries by using a striking analogy between amphiphilic ABA triblock copolymers and the hydrophilic nanorods tethered with hydrophobic polymer chains at both ends. The self-assembly was tuneable and reversible and it was achieved solely by changing the solvent quality for the constituent blocks. This approach provides a new route to the organization of anisotropic nanoparticles by using the strategies that are established for the self-assembly of block copolymers. [ABSTRACT FROM AUTHOR]

This review describes the most recent progress in the use of polymer multiresponsive microgels as central components of advanced, functional colloidal materials. Significant areas of development include the use of microgels as microreactors for templated synthesis of inorganic nanoparticles with predetermined properties, as optically active materials including lenses and photonic crystals, and as primary units in site-specific and controlled drug delivery systems. In the last category, both synthetic and biopolymeric microgels are discussed. [ABSTRACT FROM AUTHOR]

We report a strategy for the production of materials with structural hierarchy. The approach employs polymer microgels as templates for the synthesis of semiconductor, metal, or magnetic nanoparticles (NPs). We show that NPs with predetermined dimensions and size-dependent properties can be synthesized by using a very delicate balance between the reaction conditions, the composition and the structure of microgel templates, and the concentration of NPs in the microgel. Postheat treatment of microgels doped with semiconductor nanoparticles reduces NP polydispersity and allows control of their photoluminescence. Microgel templates are particularly beneficial in the synthesis of polymer microspheres heavily loaded with monodisperse superparamagnetic Fe3O4 NPs. Hybrid submicrometer-size microgels have promising potential applications in photonics, catalysis, and separation technologies. [ABSTRACT FROM AUTHOR]

Organotypic micrometre-size 3D aggregates of skin cells (multicellular spheroids) have emerged as a promising in vitro model that can be utilized as an alternative of animal models to test active ingredients (AIs) of skincare products; however, a reliable dermal spheroid-based microfluidic (MF) model with a goal of in vitro AI screening is yet to be developed. Here, we report a MF platform for the growth of massive arrays of dermal fibroblast spheroids (DFSs) in a biomimetic hydrogel under close-to-physiological flow conditions and with the capability of screening AIs for skincare products. The DFSs formed after two days of on-chip culture and, in a case study, were used in a time-efficient manner for screening the effect of vitamin C on the synthesis of collagen type I and fibronectin. The computational simulation showed that the uptake of vitamin C was dominated by the advection flux. The results of screening the benchmark AI, vitamin C, proved that DFSs can serve as a reliable in vitro dermal model. The proposed DFS-based MF platform offers a high screening capacity for AIs of skincare products, as well as drug discovery and development in dermatology. [ABSTRACT FROM AUTHOR]

Polymer hydrogels exhibit actuation properties that result in reversible shape transformations and have promising applications in soft robotics, drug delivery systems, sensors, and microfluidic devices. Actuation occurs due to differential hydrogel swelling and is generally achieved by modulating hydrogel composition. Here a different approach to hydrogel actuation that originates solely from its structural anisotropy is reported. For 3D‐printed single‐layer hydrogels formed by cellulose nanocrystals (CNCs) and gelatin methacryloyl it is shown that shear‐induced orientation of CNCs results in anisotropic mechanical and swelling properties of the hydrogel. Upon swelling in water, planar hydrogels acquire multiple complex 3D shapes that are achieved by i) varying CNC orientation with respect to the shape on the hydrogel sheet and ii) patterning the hydrogel with the regions of shear‐mediated and random CNC orientation. This study shows the capability to generate multiple shapes from the same hydrogel actuator based on the degree of its structural anisotropy. In addition, it introduces a biocompatible nanocolloidal ink with shear‐thinning and self‐healing properties for additive manufacturing of hydrogel actuators. [ABSTRACT FROM AUTHOR]

Gene expression analysis of individual cells enables characterization of heterogeneous and rare cell populations, yet widespread implementation of existing single-cell gene analysis techniques has been hindered due to limitations in scale, ease, and cost. Here, we present a novel microdroplet-based, one-step reverse-transcriptase polymerase chain reaction (RT-PCR) platform and demonstrate the detection of three targets simultaneously in over 100,000 single cells in a single experiment with a rapid read-out. Our customized reagent cocktail incorporates the bacteriophage T7 gene 2.5 protein to overcome cell lysate-mediated inhibition and allows for one-step RT-PCR of single cells encapsulated in nanoliter droplets. Fluorescent signals indicative of gene expressions are analyzed using a probabilistic deconvolution method to account for ambient RNA and cell doublets and produce single-cell gene signature profiles, as well as predict cell frequencies within heterogeneous samples. We also developed a simulation model to guide experimental design and optimize the accuracy and precision of the assay. Using mixtures of in vitro transcripts and murine cell lines, we demonstrated the detection of single RNA molecules and rare cell populations at a frequency of 0.1%. This low cost, sensitive, and adaptable technique will provide an accessible platform for high throughput single-cell analysis and enable a wide range of research and clinical applications. [ABSTRACT FROM AUTHOR]

Nanoparticle clusters with molecular-like configurations are an emerging class of colloidal materials. Particles decorated with attractive surface patches acting as analogs of functional groups are used to assemble colloidal molecules (CMs); however, high-yield generation of patchy nanoparticles remains a challenge. We show that for nanoparticles capped with complementary reactive polymers, a stoichiometric reaction leads to reorganization of the uniform ligand shell and self-limiting nanoparticle bonding, whereas electrostatic repulsion between colloidal bonds governs CM symmetry. This mechanism enables high-yield CM generation and their programmable organization in hierarchical nanostructures. Our work bridges the gap between covalent bonding taking place at an atomic level and colloidal bonding occurring at the length scale two orders of magnitude larger and broadens the methods for nanomaterial fabrication. [ABSTRACT FROM AUTHOR]

Herein we demonstrate the photothermally-triggered selfassembly of poly(N-isopropylacrylamide)-functionalized gold nanorods in one-dimensional structures. [ABSTRACT FROM AUTHOR]

Colloidal stability of nanoparticles (NPs) strongly influences their synthesis, processing, and applications. For gold NPs stabilized with cetyl trimethylammonium bromide (CTAB) and polymer ligands we show that gradual increase in polarity of the water/aprotic solvent mixture leads to stabilization–aggregation–stabilization–aggregation transitions. We propose that these transitions are mediated by structural rearrangements of the CTAB layer on the NP surface. [ABSTRACT FROM AUTHOR]

Hybrid nanoparticles composed of cellulose nanocrystals (CNCs) and carbon‐dots (C‐dots) have promising applications in chemistry, biology, and nanomedicine, owing to the photoluminescence, sensory properties, and cytocompatibility of C‐dots, and chirality, cytobiocompatibility, and high cellular uptake of CNCs. The possibility of circularly polarized luminescence in such nanoparticles is particularly attractive. Herein, scalable and straightforward hydrothermal synthesis of nitrogen‐doped fluorescent C‐dots under reflux condition by using CNCs as a carbon source and chiral substrate is reported. Under ultraviolet irradiation, hybrid C‐dot/CNC nanoparticles exhibit stronger emission of left‐handed, than right‐handed, circularly polarized light, with high dissymmetry factor up to 0.2. The nanoparticles are biocompatible: the normalized proliferation index above 100% is determined for MCF 7 cells cultured in the suspension of C‐dot/CNC nanoparticles. These hybrid nanoparticles can find applications as biotags for labeling, sensing, and therapeutics and as building blocks of photoluminescent cholesteric CNC films with photonic applications. [ABSTRACT FROM AUTHOR]

The article discusess a study conducted for achieving precise organization of nanoparticles (NPs) in three-dimensional space. It examines morphogenesis of nanoparticle assemblies and a cholesteric liquid crystalline host formed by cellulose nanocrystals for experiencing marked changes in shape and structure as a function of concentration. It mentions increase in NP loading triggers reversible droplet transformation to gain a core-shell morphology with an isotropic core.

Chiral packing of ligands on the surface of nanoparticles (NPs) is of fundamental and practical importance, as it determines how NPs interact with each other and with the molecular world. Herein, for gold nanorods (NRs) capped with end‐grafted nonchiral polymer ligands, we show a new mechanism of chiral surface patterning. Under poor solvency conditions, a smooth polymer layer segregates into helicoidally organized surface‐pinned micelles (patches). The helicoidal morphology is dictated by the polymer grafting density and the ratio of the polymer ligand length to nanorod radius. Outside this specific parameter space, a range of polymer surface structures was observed, including random, shish‐kebab, and hybrid patches, as well as a smooth polymer layer. We characterize polymer surface morphology by theoretical and experimental state diagrams. The helicoidally organized polymer patches on the NR surface can be used as a template for the helicoidal organization of other NPs, masked synthesis on the NR surface, as well as the exploration of new NP self‐assembly modes. Gold nanorods, end‐grafted with achiral polymer ligands, show a new mechanism of chiral surface patterning giving a helicoidal morphology. This morphology is dictated by the relationship between the polymer grafting density and the ratio of the polymer length to the nanorod radius. [ABSTRACT FROM AUTHOR]

Chiral packing of ligands on the surface of nanoparticles (NPs) is of fundamental and practical importance, as it determines how NPs interact with each other and with the molecular world. Herein, for gold nanorods (NRs) capped with end‐grafted nonchiral polymer ligands, we show a new mechanism of chiral surface patterning. Under poor solvency conditions, a smooth polymer layer segregates into helicoidally organized surface‐pinned micelles (patches). The helicoidal morphology is dictated by the polymer grafting density and the ratio of the polymer ligand length to nanorod radius. Outside this specific parameter space, a range of polymer surface structures was observed, including random, shish‐kebab, and hybrid patches, as well as a smooth polymer layer. We characterize polymer surface morphology by theoretical and experimental state diagrams. The helicoidally organized polymer patches on the NR surface can be used as a template for the helicoidal organization of other NPs, masked synthesis on the NR surface, as well as the exploration of new NP self‐assembly modes. [ABSTRACT FROM AUTHOR]

Abstract: Microfluidics (MFs) has emerged as a valuable and in some cases, unique platform for the synthesis and assembly of inorganic and polymeric materials. 3D printing enables time‐, labor‐, and cost‐efficient prototyping of MF devices, their durability during operation, and the ability to implement complex designs, however the applications of 3D‐printed MF devices in materials science are still in their infancy. Here, the synthesis and assembly of a diverse range of materials, including spraying‐based synthesis of inorganic NPs and conductive filaments, extrusion‐based fabrication of hydrogel fibers and sheets, and the preparation of composite solid films are reported. The properties are examined and potential applications of these materials are shown, the advantages of material fabrication in 3D‐printed MF devices are highlighted, and the directions for their further development are identified. [ABSTRACT FROM AUTHOR]

Compositional and structural patterns play a crucial role in the function of many biological tissues. In the present work, for nanofibrillar hydrogels formed by chemically cross-linked cellulose nanocrystals (CNC) and gelatin, we report a microextrusion-based 3D printing method to generate structurally anisotropic hydrogel sheets with CNCs aligned in the direction of extrusion. We prepared hydrogels with a uniform composition, as well as hydrogels with two different types of compositional gradients. In the first type of gradient hydrogel, the composition of the sheet varied parallel to the direction of CNC alignment. In the second hydrogel type, the composition of the sheet changed orthogonally to the direction of CNC alignment. The hydrogels exhibited gradients in structure, mechanical properties, and permeability, all governed by the compositional patterns, as well as cytocompatibility. These hydrogels have promising applications for both fundamental research and for tissue engineering and regenerative medicine. [ABSTRACT FROM AUTHOR]

Abstract: Chemical and topographic surface patterning of inorganic polymer‐functionalized nanoparticles (NPs) and their self‐assembly in nanostructures with controllable architectures enable the design of new NP‐based materials. Capping of NPs with inorganic polymer ligands, such as metallopolymers, can lead to new synergetic properties of individual NPs or their assemblies, and enhance NP processing in functional materials. Here, for gold NPs functionalized with polyferrocenylsilane, two distinct triggers are used to induce attraction between the polymer ligands and achieve NP self‐assembly or topographic surface patterning of individual polymer‐capped NPs. Control of polymer–solvent interactions is achieved by either changing the solvent composition or by the electrooxidation of polyferrocenylsilane ligands. These results expand the range of polymer ligands used for NP assembly and patterning, and can be used to explore new self‐assembly modalities. The utilization of electrochemical polymer oxidation stimuli at easily accessible potentials broadens the range of stimuli leading to NP self‐assembly and patterning. [ABSTRACT FROM AUTHOR]

Flow-induced alignment of shape-anisotropic colloidal particles is of great importance in fundamental research and in the fabrication of structurally anisotropic materials; however, rheo-optical studies of shear-induced particle orientation are time- and labor-intensive and require complicated experimental setups. We report a single-droplet oscillatory microfluidic strategy integrated with in-line polarized light imaging as a strategy for studies of shear-induced alignment of rod-shape nanoparticles. Using an oscillating droplet of an aqueous isotropic suspension of cellulose nanocrystals (CNCs), we explore the effect of the shear rate and suspension viscosity on the flow-induced CNC alignment and subsequent relaxation to the isotropic state. The proposed microfluidic strategy enables high-throughput studies of shear-induced orientations in structured liquid under precisely controlled experimental conditions. The results of such studies can be used in the development of structure-anisotropic materials. [ABSTRACT FROM AUTHOR]

In the search for new building blocks of nanofibrillar hydrogels, cellulose nanocrystals (CNCs) have attracted great interest because of their sustainability, biocompatibility, ease of surface functionalization, and mechanical strength. Making these hydrogels fluorescent extends the range of their applications in tissue engineering, bioimaging, and biosensing. We report the preparation and properties of a multifunctional hydrogel formed by CNCs and graphene quantum dots (GQDs). We show that although CNCs and GQDs are both negatively charged, hydrogen bonding and hydrophobic interactions overcome the electrostatic repulsion between these nanoparticles and yield a physically cross-linked hydrogel with tunable mechanical properties. Owing to their shear-thinning behavior, the CNC-GQD hydrogels were used as an injectable material in 3D printing. The hydrogels were fluorescent and had an anisotropic nanofibrillar structure. The combination of these advantageous properties makes this hybrid hydrogel a promising material and fosters the development of new manufacturing methods such as 3D printing. [ABSTRACT FROM AUTHOR]

Growth of three-dimensional cancer spheroids (CSs) in man-made hydrogels mimicking natural extracellular matrix is an important and challenging task. Herein, we report on a supramolecular temperature-responsive hydrogel designed for the growth and subsequent release of CSs. A filamentous hydrogel was formed at 37 °C from an aqueous suspension of cellulose nanocrystals surface-functionalized with temperature-responsive polymer molecules. The encapsulation of cells in the hydrogel enabled effective growth of CSs with dimensions determined by the concentration of cellulose nanocrystals in the hydrogel. On demand release of CSs without loss of cell viability and spheroid integrity was achieved upon hydrogel cooling. The tumorigenic properties of the released CSs were examined by encapsulating and re-growing them in fibrin hydrogel. The results in this work can be used in fundamental cancer research and in cancer drug screening. [ABSTRACT FROM AUTHOR]

Growth of three-dimensional cancer spheroids (CSs) in man-made hydrogels mimicking natural extracellular matrix is an important and challenging task. Herein, we report on a supramolecular temperature-responsive hydrogel designed for the growth and subsequent release of CSs. A filamentous hydrogel was formed at 37 °C from an aqueous suspension of cellulose nanocrystals surface-functionalized with temperature-responsive polymer molecules. The encapsulation of cells in the hydrogel enabled effective growth of CSs with dimensions determined by the concentration of cellulose nanocrystals in the hydrogel. On demand release of CSs without loss of cell viability and spheroid integrity was achieved upon hydrogel cooling. The tumorigenic properties of the released CSs were examined by encapsulating and re-growing them in fibrin hydrogel. The results in this work can be used in fundamental cancer research and in cancer drug screening. [ABSTRACT FROM AUTHOR]