Active colloids that convert light into motion provide insight into nonequilibrium chemical systems and routes toward microscale engines. Here we quantify the propulsion dynamics and force generation of light-activated Au-TiO2 Janus particles and their optically trappable polystyrene (PS) core-shell Au-PS@TiO2 analogues. By varying particle size, metal thickness, fuel concentration, and illumination wavelength, we show how photochemical energy conversion at the Au-TiO2 interface governs propulsion, yielding average velocities 33.2 ± 2.99 μm s-1 with instantaneous velocities up to ∼100 μm s-1. Optical tweezers measurements on single Au-PS@TiO2 Janus particles reveal transient propulsion forces with a median of 4.5-6.2 pN lasting on average 21-41 ms and reaching up to 20 pN under optical confinement. Simulations incorporating these transient forces reproduce the observed trajectories, confirming their role in driving active motion. Functionalization with long DNA polymers further enhances directional motion by reducing rotational diffusion. These results establish a single-particle framework for quantifying active forces in photocatalytic Janus particles and offer design principles for light-powered micromotors.
Malachite Green (MG), a widely used textile dye, is a toxic and non-biodegradable product commonly found in industrial wastewater. In this work, Fe3O4/g-C3N4 nanocomposites showed as an eco-friendly photocatalyst, effectively degrading the persistent pollutant to support sustainable wastewater treatment. Fe3O4 nanoparticles (NPs) were synthesized using a green route with Camellia sinensis (green tea) leaf extract method and integrated with g-C3N4, to form a hetero-structured photocatalyst. X-ray diffraction (XRD) analysis confirmed the successful formation of Fe3O4 and the preserved structural integrity of g-C3N4 structure. UV-visible diffuse reflectance spectroscopy (UV-vis DRS) revealed that Fe3O4 and g-C3N4 nanocomposites exhibit enhanced visible-light absorption. Photoluminescence (PL) spectra indicated suppressed recombination of photogenerated charge carriers, implying improved charge separation. Field emission scanning electron microscopy (FESEM) revealed a crumpled, sheet-like morphology. Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) analysis confirmed the mesoporous nature of the nanocomposites. Photocatalytic tests under visible light irradiation demonstrated a remarkable degradation efficiency of 99.20% for MG dye at pH 11, significantly outperforming the individual components. Liquid Chromatography-Mass Spectrometry (LC-MS) confirmed the presence of intermediate products, supporting a stepwise degradation mechanism of MG dye through demethylation and oxidative reactions.
Traditional liquid crystal elastomer (LCE)-based machines are constrained by the need for complex controllers and large power supplies, which limits their applicability in microrobots and other small-scale machines. In this paper, we propose a light-powered self-scrolling LCE crane, which is capable of self-scrolling to lift weights under steady light. Based on a dynamic LCE model, we derive the lateral curvature of the LCE crane and the driving moment for steady scrolling. By numerically solving the equilibrium equations, we found that the driving moment for the self-scrolling is originated from the uneven distribution of the LCE rod in the horizontal direction caused by light. The angular velocity of the self-scrolling depends on five system parameters: heat flux, coefficient of heat transfer, support spacing, weight mass, and scrolling friction coefficient. Through experimental comparative analysis, the results are consistent with the numerical simulation. The light-powered self-scrolling LCE crane device proposed in this paper features a simple structure, consistent horizontal illumination, and a compact light irradiation area. It advances the understanding of self-sustaining structures utilizing active materials and offers valuable insight into the potential applications of light-responsive LCEs in self-driven devices, medical instruments, robotics, sensors, and the energy sector.
Micro/nanorobots based on immune cells show great potential for addressing challenging biological and biomedical conditions. However, their powerful innate immune functions, particularly the phagocytosis capabilities, remain a big challenge to fully leverage with the current designs of immune cell-based microrobots. Herein, we report a light-powered phagocytic macrophage microrobot (phagobot), which is capable of robotic navigation toward specific foreign bio-threats and executing precise phagocytosis of these targeted entities under light control. Without genetic modification or nanoengineering of macrophages, the phagobot's "wake-up" program is achieved through direct activation of a resting-state macrophage by a tightly focused near-infrared (NIR) light beam. The phagobot exhibits robotic steering and directional navigation controlled by optical manipulation of the extended pseudopodia within the activated macrophage. It can further execute targeted phagocytic clearance tasks via engulfing various foreign bio-threats, including nanoplastics, microbials, and cancer cell debris. Notably, the phagobot can be constructed in a living larval zebrafish through optical activation and manipulation of the endogenous macrophage, which also exhibits controllable navigation and targeted phagocytic capabilities in vivo. With the intrinsic immune functions of macrophages, our light-powered phagobot represents a novel form of intelligent immune cell-based microrobots, holding many new possibilities for precise immune regulation and treatment for immune-related diseases.
Microbial rhodopsins are photoactive membrane proteins known for transporting small inorganic ions such as H+, Cl-, and Na+. Their compact structure─comprising seven transmembrane helices─has long been thought to limit their substrate range to such ions. Here, we report that several anion-pumping rhodopsins can also transport organic anions. In particular, a rhodopsin from cyanobacteria transports bulky organic anions, including those with a benzene ring, with volumes up to ∼120 Å3─five times larger than Cl-. These anions bind in the dark state and are translocated upon photoactivation, via a mechanism similar to Cl-. Notably, only anions with pKa values below 2 are transported, suggesting that negative charge is essential for binding. This study provides the first evidence that naturally occurring proteins can use light to transport organic compounds across membranes. These findings broaden the functional scope of microbial rhodopsins and open new possibilities for light-driven transport of organic ions.
Ruddlesden-Popper quasi-2D perovskites represent robust candidates for optoelectronic applications, achieving a delicate balance between outstanding photoresponse and stability. However, mitigating the internal defects in polycrystalline films remains challenging, and their optoelectronic performances still lag behind that of their 3D counterparts. This work highlights the profound impact of defect passivation at the buried interface and grain boundaries through a dual-cation-release strategy. Cations released from the pre-deposited inorganic iodide buffer layer effectively repair deep-level defects by inducing low-dimensional phase reconstruction and interacting with undercoordinated ions. The resulting quasi-2D perovskite polycrystalline films feature large grain size (>2 µm) and minimum surface roughness, along with alleviated out-of-plane residual tensile strain, which is beneficial for inhibiting the initiation and propagation of cracks. The fabricated photodetector demonstrates drastically improved self-powered photoresponse capability, with maximum responsivity up to 0.41 A W-1 at 430 nm and an ultrafast response speed of 161 ns / 1.91 µs. Moreover, this strategy is compatible with the photolithography-assisted hydrophobic-hydrophilic patterning process for fabricating pixelated photodetector arrays, which enables high-sensitivity imaging. This study presents a feasible defect passivation approach in quasi-2D perovskites, thereby providing insights into the fabrication of high-performance optoelectronic devices.
While DNA amplifier-built nanobiosensors featuring a DNA polymerase-free catalytic hairpin assembly (CHA) reaction have shown promise in fluorescence imaging assays within live biosystems, challenges persist due to unsatisfactory precision stemming from premature activation, insufficient sensitivity arising from low reaction kinetics, and poor biostability caused by endonuclease degradation. In this research, we aim to tackle these issues. One aspect involves inserting an analyte-binding unit with a photoinduced cleavage bond to enable a light-powered notion. By utilizing 808 nm near-infrared (NIR) light-excited upconversion luminescence as the ultraviolet source, we achieve entirely a controllable sensing event during the biodelivery phase. Another aspect refers to confining the CHA reaction within the finite space of a DNA self-assembled nanocage. Besides the accelerated kinetics (up to 10-fold enhancement) resulting from the nucleic acid restriction behavior, the DNA nanocage further provides a 3D rigid skeleton to reinforce enzymatic resistance. After selecting a short noncoding microRNA (miRNA-21) as the modeled low-abundance sensing analyte, we have verified that the innovative NIR light-powered and DNA nanocage-confined CHA nanobiosensor possesses remarkably high sensitivity and specificity. More importantly, our sensing system demonstrates a robust imaging capability for this cancer-related universal biomarker in live cells and tumor-bearing mouse bodies, showcasing its potential applications in disease analysis.
Herein, an implantable, miniature biohybrid device has been developed that utilizes light-dependent ion-gradient formation by genetically engineered human designer cells, expressing light-activated ion channels and proton pumps to generate electrical potential and deliver electrical energy. These designer cells are cultured in custom-designed polycarbonate chambers, connected by electrodes and separated from an ion reservoir by a proton-selective Nafion membrane. Upon illumination, the light-activated channels and pumps on the designer cells establish a sustained proton gradient across the Nafion membrane, which drives an electrical current in the external circuit. When exposed to simulated ambient sunlight of 3 mW cm- 2 of intensity, a single solar collection device (SCD), containing these designer cells, appropriately sized for subcutaneous implantation in mice, generates an electrical potential of ≈0.4 V. By connecting multiple SCDs in series and increasing the cell suspension volume, the output can be scaled up sufficiently to power a commercial light-emitting diode. Thus, this study demonstrates the feasibility of a photovoltaic system based on optogenetically engineered mammalian cells for powering bioelectronic implants or wearable devices.
In this paper, we propose an innovative light-powered LCE-slider system that enables continuous self-circling on an elliptical track and is comprised of a light-powered LCE string, slider, and rigid elliptical track. By formulating and solving dimensionless dynamic equations, we explain static and self-circling states, emphasizing self-circling dynamics and energy balance. Quantitative analysis reveals that the self-circling frequency of LCE-slider systems is independent of the initial tangential velocity but sensitive to light intensity, contraction coefficients, elastic coefficients, the elliptical axis ratio, and damping coefficients. Notably, elliptical motion outperforms circular motion in angular velocity and frequency, indicating greater efficiency. Reliable self-circling under constant light suggests applications in periodic motion fields, especially celestial mechanics. Additionally, the system's remarkable adaptability to a wide range of curved trajectories exemplifies its flexibility and versatility, while its energy absorption and conversion capabilities position it as a highly potential candidate for applications in robotics, construction, and transportation.
Neutron detection is widely used in many applications including nuclear physics, nuclear energy, nuclear technologies and nuclear safeguards. Developing an end-to-end neutron detection and imaging workflow paves way towards fully automated processes for many applications. We implemented an automated workflow for neutron detection experiments which use a solid state image sensor to capture neutron hits as a digital image. We deploy the workflow to an edge-based optical neural network (ONN) to increase the radiation-hardness and lifetime of neutron detection instruments. We present a two-stage neural network framework for detection of neutrons at sub-pixel resolution. The first stage uses a region proposal network to efficiently detect and extract neutron hits from the input camera image. The second stage feeds the extracted hits into a fully connected neural network to predict the sub-pixel hit position. The performance of the two-stage framework is evaluated using the edge-based ONN. The results show that we can achieve above 96% neutron detection accuracy as well as sub-pixel and sub-micron position resolution, while enjoying the advantages of the ONN hardware including radiation-hardness, low energy consumption and high computing speed for integrated edge camera and hardware deployment, when compared with electronic counterparts.
Continuous-flow photochemistry allows late-stage functionalization of N-heteroaromatics with gaseous alkane.
Biomolecular machines autonomously convert energy into functions, driving systems away from thermodynamic equilibrium. This energy conversion is achieved by leveraging complex, kinetically asymmetric chemical reaction networks that are challenging to characterize precisely. In contrast, all known synthetic molecular systems in which kinetic asymmetry has been quantified are well described by simple single-cycle networks. Here, we report on a unique light-driven [2]rotaxane that enables the autonomous operation of a synthetic molecular machine with a multi-cycle chemical reaction network. Unlike all prior systems, the present one exploits a photoactive macrocycle, which features a different photoreactivity depending on the binding sites at which it resides. Furthermore, E to Z isomerization reverses the relative affinity of the macrocycle for two binding sites on the axle, resulting in a multi-cycle network. Building on the most recent theoretical advancements, this work quantifies kinetic asymmetry in a multi-cycle network for the first time. Our findings represent the simplest rotaxane capable of autonomous shuttling developed so far and offer a general strategy to generate and quantify kinetic asymmetry beyond single-cycle systems.
In the field of sustainable chemistry, it is still a significant challenge to realize efficient light-powered space-confined catalysis and propulsion due to the limited solar absorption efficiency and the low mass and heat transfer efficiency. Here, novel semiconductor TiO2 nanorockets with asymmetric, hollow, mesoporous, and double-layer structures are successfully constructed through a facile interfacial superassembly strategy. The high concentration of defects and unique topological features improve light scattering and reduce the distance for charge migration and directed charge separation, resulting in enhanced light harvesting in the confined nanospace and resulting in enhanced catalysis and self-propulsion. The movement velocity of double-layered nanorockets can reach up to 10.5 μm s-1 under visible light, which is approximately 57 and 119% higher than that of asymmetric single-layered TiO2 and isotropic hollow TiO2 nanospheres, respectively. In addition, the double-layered nanorockets improve the degradation rate of the common pollutant methylene blue under sustainable visible light with a 247% rise of first-order rate constant compared to isotropic hollow TiO2 nanospheres. Furthermore, FEA simulations reveal and confirm the double-layered confined-space enhanced catalysis and self-propulsion mechanism.
3-Hydroxypropionic acid (3-HP) is a highly sought-after platform chemical serving as a precursor to a variety of high value-added chemical products. In this study, we designed and constructed a novel light-powered in vitro synthetic enzymatic biosystem comprising acetyl-CoA ligase, acetyl-CoA carboxylase, malonyl-CoA reductase, and phosphotransferase to efficiently produce 3-HP through CO2 fixation from acetate, a cost-effective and readily available substrate. The system employed natural thylakoid membranes (TMs) for the regeneration of adenosine triphosphate and nicotinamide adenine dinucleotide phosphate. Comprehensive investigations were conducted on the effects of buffer solutions, substrate concentrations, enzyme loading levels, and TMs loading levels to optimize the yield of 3-HP. Following optimization, a production of 0.46 mM 3-HP was achieved within 6 h from an initial 0.5 mM acetate, with a yield nearing 92%. This work underscores the simplicity of 3-HP production via an in vitro biomanufacturing platform and highlights the potential for incorporating TMs as a sustainable and environmentally friendly approach in biomanufacturing processes.
A zirconium metal-organic framework (MOF), NU-1003, along with TEMPO (2,2,6,6-tetramethylpiperidine-N-oxyl), is constructed as a system of cooperative photocatalysis for blue light-powered aerobic sulfoxidation. The incorporation of 4 mol% of TEMPO enhances the hole transfer and thereby aerobic sulfoxidation by NU-1003 photocatalysis, demonstrating the pivotal role of a redox mediator in transforming an established MOF.
In recent years, there have been many studies focused on improving the performance of active materials; however, applying these materials to active machines still presents significant challenges. In this study, we introduce a light-powered self-translation system for an asymmetric friction slider using a liquid crystal elastomer (LCE) string oscillator. The self-translation system was composed of a hollow slide, two LCE fibers, and a mass ball. Through the evolution of photothermal-induced contraction, we derived the governing equations for the system. Numerical simulations revealed two distinct motion modes: the static mode and the self-translation mode. As the mass ball moved, the LCE fibers alternated between illuminated and non-illuminated states, allowing them to effectively harvest light energy to compensate for the energy dissipation within the system. Unlike traditional self-oscillating systems that oscillate around a fixed position, the asymmetric friction enabled the slider to advance continuously through the oscillator's symmetric self-sustained oscillation. Furthermore, we explored the critical conditions necessary for initiating self-translation as well as key system parameters that influence the frequency and amplitude of the oscillator and average speed of the slider. This self-translation system, with its simple design and ease of control, holds promising potential for applications in various fields including soft robotics, energy harvesting, and active machinery.
Membrane-active molecular machines represent a recently emerging, yet important line of expansion in the field of artificial transmembrane transporters. Their hitherto demonstrated limited types (molecular swing, ion fishers, shuttlers, rotors, etc.) certainly call for new inspiring developments. Here, we report a very first motorized ion-transporting carrier-type transporter, i.e., a modularly tunable, light-powered propeller-like transporter derived from Feringa's molecular motor for consistently boosting transmembrane ion transport under continuous UV light irradiation. Based on the EC50 values, the molecular propeller-mediated ion transport activities under UV light irradiation for 300 s are 2.31, 1.74, 2.29, 2.80, and 2.92 times those values obtained without irradiation for Li+, Na+, K+, Rb+, and Cs+ ions, respectively, with EC50 value as low as 0.71 mol % for K+ ion under light irradiation.
Biological photoresponsive ion transport systems consistently attract researchers' attention owing to their remarkable functions of harvesting energy from nature and participating in visual perception systems. Designing and constructing artificial light-driven ion transport devices to mimic biological counterparts remains a challenge owing to fabrication limitations in nanoconfined spaces. Herein, a typical conjugated polyelectrolyte (PFN-Br) was assembled onto a laminated MoS2M using simple solution-processing vacuum filtration, resulting in a heterogeneous three- and two-dimensional nanoporous membrane. The designed band alignment between PFN-Br and MoS2 enables effective directional ion transport under irradiation in an equilibrium solution, even against a 30-fold concentration gradient. The staggered energy structure of PFN-Br and MoS2 enhances charge separation and establishes a photogenerated potential as the driving force for ion transport. Additionally, the activation energy barrier for ion transport across the heterogeneous membrane decreased by 60% after light irradiation, considerably improving ion transport flux. The easy fabrication and high performance of the membrane in light-powered ion transport provide promising approaches for designing nanofluidic devices with possible applications in energy conversion, light-enhanced biosensing, and photoresponsive ionic devices.
Imidacloprid (IMI) is used extensively as an insecticide and poses a significant risk to both the ecological environment and human health. Biological methods are currently gaining recognition among the different strategies tested for wastewater treatment. This study focused on evaluating a recently discovered green alga, Scenedesmus sp. TXH202001, isolated from a municipal wastewater treatment plant (WWTP), exhibited notable capacity for IMI removal. After an 18-day evaluation, medium IMI concentrations (50 and 100 mg/L) facilitated the growth of microalgae whereas low (5 and 20 mg/L) and high (150 mg/L) concentrations had no discernible impact. No statistically significant disparities were detected in Fv/Fm, Malonaldehyde or Superoxide dismutase across all concentrations, suggesting Scenedesmus sp. TXH202001 exhibited notable resilience and adaptability to IMI conditions. Most notably, Scenedesmus sp. TXH202001 successfully eliminated > 99 % of IMI within 18 days subjected to IMI concentrations as high as 150 mg/L, which was contingent on the environmental factor of illumination. Molecular docking was used to identify the chemical reaction sites between IMI and typical degrading enzyme CYP450. Furthermore, the study revealed that the primary path for IMI removal was biodegradation and verified that the toxicity of the degraded product was lower than parent IMI in Caenorhabditis elegans. The efficacy of Scenedesmus sp. TXH202001 in wastewater was exceptional, thereby validating its practical utility.