Nano- and micromotors are a class of active colloids that can self-propel outperforming Brownian motion. Polymer synthesis or degradation are alternative ways to enzyme-based or externally-driven strategies to induce self-propulsion in particles, but they are often limited due to the reaction conditions. Nature leverages biopolymerization reactions to sustain locomotion either of whole microorganisms or of organelles inside cells. With the aim of integrating natural locomotion strategies into engineered motors, we have begun to explore the propulsion mechanism of the food-borne pathogen Listeria monocytogenes, which expresses the actin-recruiting protein ActA on its surface to harness host cell actin polymerization for rapid intracellular movement. Here, we compare the locomotion of silica particles depending on the ActA immobilization strategy on the motor surface, using either homogeneous coatings, Janus-type coatings, or ActA immobilization within polymer brushes. An up to 5-fold increase in the propulsion of the motors compared to their Brownian motion is observed when Janus motors are considered. The motors orbit around or dock onto larger tracer particles depending on the environmental pH and on whether they are individuals or in clusters. Altogether, these motors illustrate how integration of concepts of the natural and synthetic world can yield unique engineered units.

Stimuli-responsive soft actuators are key components in soft robotics, enabling programmable shape changes in response to environmental cues. Here, we present a light-responsive, fish-shaped soft actuator fabricated via the 3D-printing of granular hydrogel inks composed of alginate-based microparticles. Four microparticle types with varying size and morphology were fabricated and characterized for their swelling behavior and rheological properties to optimize ink performance. Active granular hydrogel inks were prepared by infiltrating N-isopropylacrylamide (NIPAM) into microparticles to form thermoresponsive networks and embedding gold nanostars (AuNS) to introduce photothermal activity. The resulting granular inks enabled 3D printing of anisotropic structures that underwent reversible bending in response to near-infrared (NIR) light. A fish-shaped actuator, composed of an active AuNS-PNIPAM tail and passive body, exhibited reproducible bending over nine actuation cycles with change in bending angles stabilizing at similar to 37 degrees after initial thermal conditioning. Our findings highlight the potential of modular, granular ink formulations to produce programmable soft robotic systems with remote, light-triggered control.

The interplay between biomolecular condensates and cellular membranes is central to understanding dynamic intracellular organization and membrane repair. Here, we present a minimal synthetic system to examine how membrane composition and curvature govern condensate-membrane interactions within this model platform. We demonstrate that the exposure of either lipid or polymer-lipid hybrid giant vesicles with encapsulated bovine serum albumin to a resilin-inspired intrinsically disordered protein (IDP), which undergoes liquid-liquid phase separation, results in in situ formation of transmembrane condensates. This observation of cargo-triggered condensation across giant vesicle membranes directly links encapsulated protein crowding to condensate nucleation and insertion. The condensation morphology was tunable by vesicle size and membrane elasticity where smaller vesicles and stiffer hybrid membranes favored transmembrane condensation, whereas larger or softer membranes promoted membrane wetting and deformation. Condensate formation locally reorganized lipids and facilitated leaflet coupling without compromising overall membrane integrity or cargo retention. This mechanistic understanding offers a unique opportunity to gain insight into the complex cell biological process of membrane repair using a minimal system.

Synthetic catalytic antioxidants offer attractive alternatives to enzymatic redox regulators, yet their biological application is frequently limited by poor stability, formulation challenges, and insufficient control over intracellular localization. Here, we report a lipid conjugation strategy that enables the covalent integration of manganese Salen (EUK) catalysts into phospholipid membranes. A modular synthetic route is established in which a carboxylate-functionalized EUK derivative is coupled to an amine-terminated phospholipid tail, yielding a structurally defined phospholipid-EUK conjugate that retains catalytic activity upon liposome formulation, with controlled catalyst loading and long-term colloidal integrity. The resulting liposomes exhibit efficient catalytic degradation of reactive oxygen species (ROS) with activity scaling with conjugate content. Importantly, covalent anchoring of the catalyst within the lipid bilayer prevents aggregation and precipitation observed for non-conjugated analogues. Using an acetaminophen challenged steatotic HepaRG cell model, we demonstrate that lipid conjugation enables intracellular delivery of the catalyst and sustained reduction of elevated ROS levels without inducing cytotoxicity. This effort establishes a chemically precise approach for positioning organometallic catalysts within biomimetic membranes and highlights these conjugates as versatile platforms for controlled intracellular redox modulation.

Active colloids have attracted enormous attention in the past two decades. The field has evolved rapidly, resulting in diverse motor designs used to navigate in different environments. However, the question of the extent to which 2D and 3D analysis methods can be directly compared remains challenging to address. Here, we relate the motion of particles when assessed by fluorescence correlation spectroscopy (FCS) in a 3D volume to the standard optical microscopy-based tracking method in 2D. We select three types of motors that exemplify different common mechanisms of propulsion, i.e., self-diffusiophoresis, bubble propulsion, and magnetic guidance. We define minimal FCS detectability criteria for colloids and apply conditions to quantify locomotion of single and mixed motor populations. Specifically, we can distinguish between a mixed population of active and passive colloids in the same solution. Extending the existing FCS model, we can assess directed particle motion, which provides estimated velocities close to those reported by optical tracking methods. The results suggest that, while FCS and optical tracking show consistent trends in motor dynamics, they can differ in the absolute values of the effective diffusion coefficient. Nonetheless, FCS enables reliable assessment of the transport properties of motors when appropriate data treatment and evaluation procedures are applied. Taken together, FCS and optical tracking are complementary methods to determine the diffusivity values of the entire particle population and individual motors, respectively.

The assembly of synthetic systems with the ability for protein-mediated division remains a challenge in bottom-up synthetic biology. Here, the reconstitution of an active Drs2p-Cdc50p lipid flippase in polymer lipid hybrid vesicles (HVs) made from phospholipids and 1 or 2.5 mol% amphiphilic block copolymers, with poly(carboxyethyl acrylate) or poly(6-O-methacryloyl-d-galactopyranose) as the hydrophilic extension and either cholesteryl methacrylate or butyl methacrylate or combinations thereof as the hydrophobic blocks is demonstrated. The reconstitution of Drs2p-Cdc50p in HVs flip 2-dioleoyl-sn-glycero-3-phospho-l-serine (DOPS) lipids from the inner to the outer leaflet, leading to transmembrane asymmetry. Importantly, the chemical nature of the hydrophobic block in the amphiphilic block copolymers used to assemble the HVs is crucial to support changes in the spontaneous curvature of the bilayers due to translocation of DOPS lipids that results in HV constriction and division. Taken together, this effort is a step forward in imitating cell division in synthetic assemblies toward potentially bottom-up assembled self-replicating units.

The integration of artificial and mammalian cells into semi-synthetic aggregates remains a challenge in bottom-up synthetic biology. Here, the fabrication of cell membrane vesicles (CMV) from HepG2 cells and their use as a coating for alginate microgels to produce camouflaged artificial cells (ACs) is demonstrated. These ACs are used for the assembly of either synthetic aggregates or semi-synthetic aggregates. In the first case, a predator-defendant and a liver-like synthetic aggregates are investigated, showing promising initial steps toward complex synthetic aggregates. In the other case, the camouflaged ACs show enhanced integration with HepG2 cells. The encapsulation of a reactive oxygen species (ROS) scavenger artificial enzyme in the ACs shows protection against tert-butyl hydroperoxide in terms of HepG2 cell viability, proliferation, and mitochondrial health in semi-synthetic aggregates. Taken together, this effort is a substantial step forward in combining mammalian cells and ACs in the same aggregate where the latter act as support units.

Artificial cells are man-made systems that imitate specific functions of biological cells to study or harness cellular behavior. Biological cells can respond to external forces and signals by altering their shape, undergoing deformation, and generating the mechanical forces required for their movement. The cytoskeleton orchestrates this process through the coordinated action of actin filaments, intermediate filaments, and microtubules. Examples of artificial cells that sense and adapt to changes in their environment owing to cytoskeleton rearrangement have extensively been explored. These efforts focus on the use of biomolecules that stochastically self-assemble in the lumen of an artificial cell. Here, we employ actin polymerizing nanomotors to assist cytoskeleton formation inside artificial cells. Nano- and micromotors are a class of active colloids that can self-propel outperforming Brownian motion. Inspired by natures' way of leveraging biopolymerization reactions to sustain locomotion in microorganisms or in organelles within cells, we imitate the mechanism of motion of the food-born bacteria Listeria monocytogenes. Specifically, we coat polystyrene particles with an actin recruiting protein that allows for actin filament polymerization in a mammalian cell lysate environment. This polymerization results in up to a 3-fold increase in the propulsion of the motors compared to their Brownian motion. Lastly, we show that these motors can be encapsulated inside hybrid vesicle-based artificial cells made of amphiphilic block copolymers and phospholipids, forming actin filaments that assemble into a cytoskeleton-like network. Taken together, this effort highlights the synergistic integration of bottom-up synthetic biology and active matter, demonstrating how their convergence can advance the design of life-like systems.

Creating artificial cells with a dynamic cytoskeleton, akin to those in living cells, is a major goal in bottom‐up synthetic biology. In this study, we demonstrate the in situ polymerization of microtubules encapsulated in giant polymer‐lipid hybrid vesicles (GHVs) composed of 1,2‐dioleoyl‐ sn ‐glycero‐3‐phosphocholine and an amphiphilic block copolymer. The block copolymer is comprised of poly(cholesteryl methacrylate‐ co ‐butyl methacrylate) as the hydrophobic block and either poly(6‐O‐methacryloyl‐D‐galactopyranose) or poly(carboxyethyl acrylate) as the hydrophilic extension. Depending on the concentrations of guanosine triphosphate (GTP) or its slowly hydrolyzable analog, guanosine‐5′‐[(α,β)‐methyleno]triphosphate (GMPCPP), different microtubule morphologies are observed, including encapsulated microtubule networks, spike protrusions, as well as membrane‐associated or aggregated microtubules. Overall, this work represents a step forward in mimicking the cellular cytoskeletons and uncovering the influence of membrane composition on microtubule morphologies.

Inspired by Richard Feynman's 1959 lecture and the 1966 film Fantastic Voyage, the field of micro/nanorobots has evolved from science fiction to reality, with significant advancements in biomedical and environmental applications. Despite the rapid progress, the deployment of functional micro/nanorobots remains limited. This review of the technology roadmap identifies key challenges hindering their widespread use, focusing on propulsion mechanisms, fundamental theoretical aspects, collective behavior, material design, and embodied intelligence. We explore the current state of micro/nanorobot technology, with an emphasis on applications in biomedicine, environmental remediation, analytical sensing, and other industrial technological aspects. Additionally, we analyze issues related to scaling up production, commercialization, and regulatory frameworks that are crucial for transitioning from research to practical applications. We also emphasize the need for interdisciplinary collaboration to address both technical and nontechnical challenges, such as sustainability, ethics, and business considerations. Finally, we propose a roadmap for future research to accelerate the development of micro/nanorobots, positioning them as essential tools for addressing grand challenges and enhancing the quality of life.

Nano/micromotors are self-propelled particles that show enhanced motion upon being triggered by a stimulus.

Amphiphilic block copolymer and lipids can be assembled into hybrid vesicles (HVs), which are an alternative to liposomes and polymersomes. Block copolymers that have either poly(sitostryl methacrylate) or statistical copolymers of sitosteryl methacrylate and butyl methacrylate as the hydrophobic part and a poly(carboxyethyl acrylate) hydrophilic segment are synthesized and characterized. These block copolymers assemble into small HVs with soybean L-α-phosphatidylcholine (soyPC), confirmed by electron microscopy and small-angle X-ray scattering. The membrane's hybrid nature is illustrated by fluorescence resonance energy transfer between labeled building blocks. The membrane packing, derived from spectra when using Laurdan as an environmentally sensitive fluorescent probe, is comparable between small HVs and the corresponding liposomes with molecular sitosterol, although the former show indications of transmembrane asymmetry. Giant HVs with homogenous distribution of the block copolymers and soyPC in their membranes are assembled using the electroformation method. The lateral diffusion of both building blocks is slowed down in giant HVs with higher block copolymer content, but their permeability toward (6)-carboxy-X-rhodamine is higher compared to giant vesicles made of soyPC and molecular sitosterol. This fundamental effort contributes to the rapidly expanding understanding of the integration of natural membrane constituents with designed synthetic compounds to form hybrid membranes.

Hydrogel-based actuators are innovative materials that exhibit responsive and dynamic behavior in response to external stimuli, making them promising candidates for a wide range of applications in fields such as soft robotics. We employ 3D printing to create layered rectangles, using a passive ink composed of gelatin methacryloyl (GelMA) and an active ink consisting of GelMA and poly(N-isopropylacrylamide) (PNIPAM). Our aim is to assess and compare the bending capabilities of these structures based on their layer arrangements in a buffer above the lower critical solution temperature. Therefore, an asymmetric rectangular structure is selected as the shape-changing component in the tail of a 3D printed fish-shaped hydrogel actuator. We show that gold nanostars integrated into the actuators serve as photothermal elements, enabling the fish tail to repeatedly bend when near infrared light is turned on and off. Our effort illustrates the potential of combining 3D printing, responsive hydrogels and photothermal elements with near infrared light towards soft robotic applications. This combination yields actuators capable of shape-shifting without requiring localized light or transitioning between environments with varying temperatures.

Hybrid vesicles, made of lipids and amphiphilic block copolymers, have become increasingly popular thanks to their versatile properties that enable the construction of intricate membranes mimicking cellular structures. This tutorial review gives an overview over the different hybrid vesicle designs, and provides a detailed analysis of their properties, including their composition, membrane fluidity, membrane homogeneity, permeability, stability. The review puts emphasis on the application of these hybrid vesicles in bottom-up synthetic biology and aims to offer an overview of design guidelines, particularly focusing on composition, to eventually realize the intended applications of these hybrid vesicles.

Intracellular reactive oxygen species (ROS) in steatotic cells pose a problem due to their potential to cause oxidative stress and cellular damage. Delivering engineered phospholipids to intracellular lipid droplets in steatotic hepatic cells, using the cell's inherent intracellular lipid transport mechanisms are investigated. Initially, it is shown that tail-labeled fluorescent lipids assembled into liposomes are able to be transported to intracellular lipid droplets in steatotic HepG2 cells and HHL-5 cells. Further, an antioxidant, an EUK salen-manganese derivative, which has superoxide dismutase-like and catalase-like activity, is covalently conjugated to the tail of a phospholipid and formulated as liposomes for administration. Steatotic HepG2 cells and HHL-5 cells incubated with these antioxidant liposomes have lower intracellular ROS levels compared to untreated controls and non-covalently formulated antioxidants. This first proof-of-concept study illustrates an alternative strategy to equip native organelles in mammalian cells with engineered enzyme activity. The level of intracellular reactive oxygen species (ROS) in steatotic cells is lowered by delivering tailored phospholipids to lipid droplets via intrinsic intracellular transport mechanisms. Fluorescent lipids and a EUK salen-manganese derivative conjugated to lipids, both formulated as liposomes, effectively target intracellular lipid droplets in steatotic HepG2 and HHL-5 cells, leading to reduced intracellular ROS levels. image

Nano/micromotors outperform Brownian motion due to their self-propulsive capabilities and hold promise as carriers for drug delivery across biological barriers such as the extracellular matrix. This study employs poly(2-(diethylamino)ethyl methacrylate) polymer brushes to enhance the collagenase-loading capacity of silica particle-based motors with the aim to systematically investigate the impact of gelatine viscosity, motors' size, and morphology on their propulsion velocity. Notably, 500 nm and 1 mu m motors achieve similar speeds as high as similar to 15 mu m s-1 in stiff gelatine-based hydrogels when triggered with calcium. Taken together, our findings highlight the potential of collagenase-based motors for navigating the extracellular matrix, positioning them as promising candidates for efficient drug delivery. Motors equipped with collagenase trapped in polymer brushes exhibit high speeds of up to similar to 15 mu m s-1 in stiff gelatine hydrogels when activated with calcium, showing potential as effective carriers for drug delivery across the extracellular matrix.

Designing and assembling artificial cells (ACs) is a core direction in bottom-up synthetic biology. Here, the advancements in the past 3 years in engineering ACs with focus on compartmentalization and surface modifications with the aim for their integration in semi-synthetic tissue are outlined. Compartmentalization in vesicles, coacervates and hydrogels are discussed for encapsulated catalysis or cytoskeleton formation including the use of components of mammalian cells to increase the ACs' complexity. Following on, the surface modification of the ACs is reviewed due to its relevance when integration of ACs with mammalian cells into semi-synthetic tissue is the goal. Finally, the interaction of ACs and mammalian cells for cellular communication or the fabrication of semi-synthetic tissue toward therapeutic opportunities is outlined, before a short perspective is provided. The advancement in engineering artificial cells over the past 3 years is discussed, focusing on compartmentalization and surface modification. Furthermore, the elements necessary for beneficial interaction and integration of artificial cells and mammalian cells are discussed, with the objective of assembling semi-synthetic tissues. image

Integration of living cells with extrinsic functional entities gives rise to bioaugmented nanobiohybrids, which hold tremendous potential across diverse fields such as cell therapy, biocatalysis, and cell robotics. This study presents a biocompatible method for incorporating multilayered functional liposomes onto the cell surface, creating extracellular artificial organelles or exorganelles. The introduction of various extrinsic functionalities to cells is achieved without comprising their viabilities. The integration of extrinsic enzymatic reactions is exemplified through the cascade reaction involving glucose oxidase and horseradish peroxidase. Furthermore, our protocol offers the design flexibility to customize liposome compositions, thereby providing effective cell modification. The versatility of the liposome-based exorganelle approach establishes an advanced chemical tool, empowering cells with novel functionalities that surpass or are complementary to their innate capabilities.