Detecting small extracellular vesicles is critical for understanding disease biology and developing diagnostic tools, yet current methods require lengthy isolation steps and lack sensitivity owing to interference from abundant proteins. Here we report on an assay that uses Janus particles that enable rapid, isolation-free detection by exploiting Brownian rotation-induced blinking changes. When vesicles bind, their size significantly alters the blinking frequency, while smaller proteins produce no signal, ensuring selectivity. Using less than 10 μl of sample, the assay detects approximately 200 vesicles per microlitre and works directly on plasma, serum, urine and cell media in under 1 h. In a blind study of 87 subjects with colorectal cancer, pancreatic ductal adenocarcinoma, glioblastoma, Alzheimer's disease and healthy controls, the method identified disease type with an area under the curve of 0.90-0.99. Compared with ultracentrifugation combined with surface plasmon resonance, which requires 24 h, our approach delivers 2 orders of magnitude better sensitivity and dynamic range, offering a fast and robust platform for clinical and research applications.

A highly efficient anti-icing/de-icing surface designed with Janus particle encapsulated phase-change microcapsules exhibits photothermal performance and superhydrophobicity

From Janus Spheres to Twisted Patchy Platelets and Their 3D Assemblies by Co-Crystallization-Driven Self-Assembly

An efficient strategy to separate nanoplastics from water using anisotropic magnetic Janus particles.

Interface modification via a sizing agent is a crucial strategy for improving mechanical properties of a glass fiber (GF) reinforced polypropylene (PP) composite. In this work, soft-hard Janus particles (JPs) were designed and synthesized by polymerization-induced phase separation of seeded emulsion and incorporated into a waterborne GF sizing agent for interface modification. The JPs-sized GF exhibited enhanced surface roughness (Ra) from 6.3 to 23.1 nm and reduced polar surface energy from 30.20 mJ/m2 to 25.48 mJ/m2. The soft-hard segmented structure of JPs formed a gradient modulus interphase layer with a thickness of about 244 nm that dissipated fracture energy through microdeformation. The JPs modification can enhance the interfacial adhesion with their amphiphilicity, introduce nanoscale roughness at the interface, and construct a gradient modulus interphase layer synergistically, which resulted in strengthening and toughening the short GF reinforced PP composite simultaneously. It reveals the promising application of JPs in advanced composite interfacial engineering.

Directed motion of particles is typically explained by phoretic mechanisms arising under externally imposed chemical, electric, or thermal gradients. In contrast, chemical reactions can enhance particle diffusion even in the absence of such external gradients. We refer to this increase as active diffusivity, often attributed to self-diffusiophoresis or self-electrophoresis, although these mechanisms alone do not fully account for experimental observations. Here, we investigate active diffusivity in catalytic Janus particles immersed in reactive media without imposed gradients. We show that interfacial reactions generate excess surface energy and sustained interfacial stresses that supplement thermal energy, enabling diffusion beyond the classical thermal limit. We consistently quantify this contribution using both dissipative and nondissipative approaches, assuming that the aqueous bath remains near equilibrium. Our framework reproduces experimentally observed trends in diffusivity versus activity, including the nonmonotonic behaviors reported in some systems, and agrees with data for nanometric Janus particles catalyzing charged substrates as well as vesicles with membrane-embedded enzymes driven by ATP hydrolysis. These results demonstrate that chemical reactions can induce and sustain surface-tension gradients and surface excess energy, providing design principles for tuning mobility in synthetic active matter.

ABSTRACT Complex multiphase emulsions containing liquid crystals (LCs) offer precise morphological control and dynamic tunability, enabling applications in optics, sensing, and soft matter. Here, we report a simple and scalable bulk‐emulsification strategy that circumvents the reliance on microfluidic fabrication to produce liquid crystalline network (LCN) microparticles spanning single, double (Janus), and triple emulsion morphologies within a genuinely colloidal size regime (10–20 µm). By adjusting crosslinking density and interfacial conditions, we program the LC alignment within the droplets, thereby dictating the mode and direction of actuation after photopolymerization. Single emulsions, Janus particles—coupling an active LCN hemisphere to a passive PDMS compartment—and, for the first time, triple LC emulsions—incorporating a third immiscible phase (a fluorinated oil)—are obtained via this straightforward and scalable approach. Across all morphologies, the particles exhibit robust, reversible, large‐amplitude deformations under heating, as well as chemoresponsivity through anisotropic swelling in organic solvents. In addition, the Janus particles exhibit gravitational self‐orientation, while the triple LC emulsions retain their multiphase architecture and display tunable geometries. As a proof of concept, these responsive behaviors are exploited to realize adaptive microlenses with thermally tunable focal plane and magnification, establishing complex LC emulsions as a scalable platform for multifunctional microactuators.

In this work, we discuss the development of an active colloidal system with controllable interactions with an artificial lipid bilayer membrane as a model for investigating the interplay of membrane mechanics and the transport of particles during adhesion and wrapping. We use polystyrene microspheres coated with a hemispherical platinum cap as model swimmers whose active motion is initiated by the addition of hydrogen peroxide (H2O2). Two classes of particle-membrane interactions and particle swimming direction are assessed. For the former, carboxylated particles are used to passively interact with the membrane through electrostatic interactions, while streptavidin coated particles are used to form a strong bond with biotinylated lipid membranes. For the latter, these active Janus particles are designed to be "pushers", which swim toward their metal face into the bilayer, or "pullers", which swim away from the membrane, by changing the concentration of CTAB, a cationic surfactant, in the aqueous phase. We find that a negative gravitaxis effect causes the steady movement of unbound pullers up and away from the membrane with increasing H2O2. When the particles are bound, a threshold H2O2 concentration is needed before overcoming the strength of the biotin-neutravidin bond and releasing the particles from the interface. In the case of the pusher system, as the H2O2 concentration increases the particles become increasingly wrapped in the membrane, as evidenced by their altered translational and rotational dynamics. We apply active Brownian models to characterize the nature of the particle-membrane interactions and also particle pair interactions. These results lay the groundwork to combine active colloidal systems with model lipid membranes to understand active transport in cellular contexts.

Precise spatial confinement of enzymes at oil-water interfaces offers an elegant strategy to enhance biphasic catalysis yet achieving robust and recyclable interfacial assemblies remains challenging. Here, we introduce an amphiphilic polymeric Janus particle platform that enables lipases to preferentially localize at interfaces, thereby achieving efficient Pickering interfacial catalysis (PIC). Crosslinked poly(hydroxypropyl methacrylate) colloids bearing surface carboxylic acid groups were synthesized via RAFT-mediated heterogeneous copolymerization and further transformed into snowman-shaped Janus particles through seeded emulsion polymerization. The resulting amphiphilic Janus colloids possess distinct hydrophilic-hydrophobic domains that facilitate both enzyme anchoring and emulsion stabilization. Candida rugosa lipase (CRL) immobilized on these particles exhibited strong interfacial activity, achieving enhanced catalytic efficiency, thermal stability, and recyclability compared to free CRL. The present work suggests that enzyme immobilization on Janus colloids is a promising approach to advance next-generation PIC.

The stress tensor is calculated for dilute active suspensions composed of colloidal Janus particles propelled by self-diffusiophoresis and powered by a chemical reaction. The Janus particles are assumed to be spherical and made of catalytic and non-catalytic hemispheres. The reaction taking place on the catalytic part of each Janus particle generates local molecular concentration gradients at the surface of the particle and, thus, an interfacial velocity slippage between the fluid and the particle, which is the propulsion mechanism of self-diffusiophoresis. In the dilute-system limit, the contributions of the suspended particles to the stress tensor are calculated by solving the linearised chemohydrodynamic equations for the fluid velocity and the molecular concentrations around every Janus particle considered as isolated and far apart from each other. The results are the following. First, the well-known Einstein formula for the effective shear viscosity of colloidal suspensions is recovered, including the effect of a possible uniform Navier slip length. Next, two further contributions are obtained, which depend on the molecular concentrations of the fuel and product species of the reaction, on the concentration gradients, and on the orientation of the Janus particles. The second contribution is caused by simple diffusiophoresis, which already exists in passive suspensions with global concentration gradients and no reaction. The third contribution is due to the self-diffusiophoresis generated by the chemical reaction, which arises in active suspensions. The calculation gives quantitative predictions based on the geometry of the Janus particles and on the constitutive properties of the fluid and the fluid–solid interfaces.

Optical manipulation of metallic Janus particles via self-thermophoresis results in complex trajectories due to competing effect of space-dependent speed and optical torque with the optical trapping presumed to have less or no effect. Here we report that when the beam size is comparable to the size of the particle and the laser power is small, optical trapping becomes relevant leading to the trajectory having a trochoidal-like behavior and off-center trapping. Brownian dynamics simulation incorporating space-dependent speed proportional to the local laser intensity, the induced optical torque, and optical trapping effect captures well the experimental data.

Understanding and controlling the motion of self-propelled particles in complex fluids is crucial for applications in targeted drug delivery, microfluidic transport, and the broader field of active matter. Here, we investigate the thermophoretic self-propulsion of partially gold-coated polystyrene Janus particles (Au-PS) in temperature-responsive linear poly(N-isopropyl acrylamide) (PNIPAM) solutions across various concentrations and temperatures. Particle velocities are examined at three representative temperatures: room temperature ((21 ± 0.2) °C), (28 ± 1) °C (just below the LCST), and (34 ± 1) °C (above the LCST). Viscosity values of the PNIPAM solutions were found to be close to those of pure water, with no significant shear thinning or other viscoelastic effects observed under relevant experimental conditions. In pure water, Au-PS Janus particles propel with the PS hemisphere leading, driven by their intrinsic thermophoretic response. At low polymer concentrations (0.05 wt%), experiments and theoretical calculations reveal a non-monotonic dependence of particle velocity on temperature, with a maximum near the LCST. In this regime, the positive Soret coefficient of PNIPAM causes the polymer to accumulate near the cooler PS hemisphere, generating a diffusiophoretic drift that can dominate the intrinsic thermophoretic motion and reverse the propulsion direction. Experimentally, the propulsion direction switches from PS-forward to Au-forward between 0.04 wt% and 0.05 wt%, and within the 0.05 wt% solution, a secondary reversal back to PS-forward is observed at higher temperatures, consistent with the weakening of the depletion-induced drift above the LCST. At higher concentrations (0.5 wt% and 1 wt%), the increased polymer content leads to stronger adsorption onto the entire particle surface, which suppresses propulsion by reducing local asymmetry. At 34 °C, thermophoretic propulsion stops, leaving only Brownian motion. Additionally, the diffusion coefficient increases due to temperature raise. These results highlight the potential of thermo-responsive polymers to control microswimmer dynamics, offering tunable transport properties for applications in active matter and targeted delivery systems.

Simultaneous detection of tetracycline and aflatoxin M1 using constructing Janus particles functionalized by molecular imprinting and aptamer.

This study presents a novel approach to electronically steering X rays using Janus spheres arranged in multiple layers, each reflecting at an example 4o Bragg angle.

Anisotropic colloidal particles serve as valuable models for fundamental research and as versatile building blocks for functional materials. Our previous work (Luo et al. Soft Matter 2021, 17, 10696) demonstrated that delaying the addition of the cross-linker divinylbenzene (DVB) creates seeds whose surfaces bear one large shell buckling-induced indentation (SBI) and several smaller phase-separated indentations (PSIs). When these dented seeds are subjected to seeded emulsion polymerization, monomer selectively nucleates at the dent sites; however, the factors governing this site preference remain unclear. Here, we systematically varied the delayed feeding time td of DVB to prepare seeds bearing well-defined dents and subjected them to seeded emulsion polymerization. Particles with coexisting rough and smooth surface domains were obtained. Under identical temperature, amount of monomer and initiator conditions, monomer preferentially nucleates within the SBI of low-td seeds (td ≤ 3.5 h), yielding one larger protrusion at the SBI site and finer protrusions at the PSIs ones; conversely, for high-td seeds (td = 4.5 h), nucleation within one of the PSIs of the seeds produces larger protrusion. Raising the temperature or initiator concentration smooths the originally rough seed surface, resulting in Janus particles with one smooth and one rough lobe. As buckling and phase separation impart distinct cross-link densities to SBI and PSIs, we ascribe the observed site selectivity and surface roughness to spatial variations in seed cross-linking. Our approach offers a simple route to Janus particles whose protrusion locations and roughness can be programmed, providing a flexible platform for next-generation functional colloids.

Anisotropic Janus Particles with Variable Morphology via Controllable Polymerization-Induced Phase Separation of Core–Shell Structure

Enzyme-powered nanomotor probes for enhanced sensitivity in lateral flow immunoassay of aflatoxin B1

The locomotion of a self-diffusiophoretic Janus particle in a complex medium is crucial for biomedical applications. In this work, the self-propulsion of a spherical Janus particle in a Brinkman medium is studied by developing a coupled mathematical model integrating solute diffusion with Brinkman flow equations. Notably, the law of the particle's self-diffusiophoretic speed, power dissipation, and swimming efficiency are investigated with the surface coverage and swimming resistance. Numerical results show that the distribution of propulsion speed is symmetric regarding the surface coverage, and the relative propulsion speed is independent of surface coverage. The relative power dissipation is increased significantly with swimming resistance when the swimming resistance exceeds a critical value. Additionally, swimming efficiency demonstrates non-monotonic behavior with variations of resistance. Our numerical results may further guide the design of synthetic active particles capable of efficient operation within complex physiological environments.

One-step microfluidic synthesis of Janus particles with controllable magnetic nanoparticle proportion and their magnetoresponsive motion

Abstract We report a novel method for fabricating Janus particles using photodegradable core–shell structures composed of poly(methyl methacrylate) (PMMA) cores and poly(di-n-butylsilane) (PDBS) shells. Upon ultraviolet irradiation (320 nm), the PDBS shell selectively decomposes, exposing the PMMA core and forming Janus-type particles. SEM and X-ray photoelectron spectroscopy analyses confirmed the formation of core–shell structures and successful photodegradation. This approach enables control over patch morphology, offering a versatile platform for designing colloidal architectures with tailored interparticle interactions.