Robotics has long pursued the development of systems that can control physical objects remotely and precisely in diverse environments. With ongoing miniaturization, micro-robots have emerged as promising platforms for a wide range of applications. In particular, magnetic micro-robots are compelling because external magnetic fields provide a wireless and biocompatible means of actuation, overcoming the constraints of on-board power sources in confined and complex settings. Despite extensive studies, the classification of magnetic micro-robots has often remained indistinct. This review seeks to contribute a more systematic understanding by defining four major categories—rigid, reconfigurable, shape-changing, and swarm—while also discussing emerging hybrid systems that bridge these paradigms. We synthesize the fundamental actuation principles and representative designs of each category. By examining the capabilities and limitations of each paradigm, we identify challenges and outline future directions for the advancement of adaptive and intelligent magnetic micro-robotic systems. The field of robotics is advancing towards creating micro-robots capable of operating in confined and complex environments. This review explores magnetic micro-robots, which use external magnetic fields for actuation, bypassing the limitations of onboard power sources. The authors categorize these robots into four types: rigid, reconfigurable, shape-changing, and swarm micro-robots, each with unique structural and functional attributes. Rigid micro-robots offer precision but lack adaptability, while reconfigurable robots can change shape for varied tasks. Shape-changing robots provide continuous morphological flexibility, and swarm robots leverage collective intelligence for large-scale tasks. The authors also highlight emerging hybrid systems that integrate multiple adaptive behaviours, allowing magnetic micro-robots to switch between distinct modes of operation in response to changing tasks and environments. These advances suggest a promising future for magnetic micro-robots in biomedical, environmental, and manufacturing applications.
Photoinitiators offer an energy-saving alternative to thermal initiation, initiating free-radical polymerization through irradiation. Despite their benefits, current photoinitiators face issues of toxicity and solubility. Trifluoromethylphenyl diazirine, an aryl diazirine, is a promising photoinitiator that generates a carbene upon exposure to light. Aryl diazirines exhibit favorable optical and molecular properties, including minimal skin sensitization and liquid miscibility with aqueous and organic resins. Experimental studies demonstrate the ability of aryl diazirines to initiate free-radical polymerization of acrylate monomers, offering several advantages over traditional photoinitiators, such as TPO and BAPO. Aryl diazirines’ unique attributes include low cytotoxicity, prevention of resin shrinkage, and removal of unreacted monomers post-curing. R-group variants enable both UV and visible-light activation, thereby expanding their utility across biomedical and industrial sectors. The study explores the potential of aryl diazirines as photoinitiators for acrylate polymerization, addressing the limitations of current photoinitiators like toxicity and solubility. The authors hypothesize that aryl diazirines, with electron-withdrawing or alkyl para-substituents, can initiate radical polymerization effectively. They employ photorheometry to assess the polymerization process under various wavelengths and conditions, comparing results with commercial photoinitiators. The findings reveal that aryl diazirines achieve comparable mechanical properties to TPO, with advantages such as lower skin sensitization and better solubility in water-based resins. These properties make aryl diazirines promising for applications in biomedical fields and sustainable manufacturing. The study suggests future exploration of diazirines in 3D printing and bioadhesives, emphasizing their potential as non-toxic alternatives to traditional photoinitiators. This summary was initially drafted using artificial intelligence, then revised and fact-checked by the author. Aryl diazirines as a new class of photoinitiators. Irradiation of an aryl diazirine releases N2 and generates a triplet carbene that initiates free-radical polymerization of acrylate monomers through a hypothesized hydrogen abstraction mechanism. Unlike commercial photoinitiators, aryl diazirines exhibit unique benefits like being miscible liquids in both organic and aqueous environments, exhibit minimal cytotoxicity, and can absorb residual vinyl monomer through the diazoalkane isomer. The para-substituent tunes activation wavelength from 365 to 445 nm and nitrogen evolution offsets cure shrinkage.
Sulfate radical (SO₄•⁻)-based advanced oxidation processes (SR-AOPs) offer high redox potential, long half-life, and superior selectivity for degrading persistent pollutants in wastewater. However, challenges remain in developing high-activity, recoverable, and reusable catalysts using non-noble metals. Here, we report a high-performance catalyst by immobilizing cobalt pyroborate (Co₂B₂O₅) onto dendritic fibrous silica (KCC-1), enabling efficient peroxymonosulfate (PMS) activation for degrading 4-nitrophenol (4-NP), tetracycline (TC), and sulfamethoxazole (SMX). The optimized Co₂B₂O₅@KCC-1 catalyst (Si/Co = 6, B/Co = 1.5) exhibited 1.6-, 1.9-, and 4.6-fold activity enhancements over CoₓOᵧ@KCC-1, Co₂B₂O₅@MCM-41, and one-pot synthesized Co–B@KCC-1, respectively, underscoring the synergistic benefits of the pyroborate phase and fibrous silica support. This enhanced performance stems from the synergistic integration of redox-active Co₂B₂O₅ with the high-surface-area, radially porous KCC-1 framework, which enables uniform dispersion, increased active site accessibility, and accelerated mass transport. Reactive oxygen species (ROS) trapping and EPR analyses confirmed the generation of surface-bound SO₄•⁻ and singlet oxygen (¹O₂), suggesting coexisting radical and non-radical oxidation pathways. XPS revealed dynamic Co²⁺/Co³⁺ redox transitions during PMS activation, while Bader charge analysis via DFT showed that borate ligands reduce Co electron density by ~0.16 |e| relative to Co₃O₄, facilitating redox cycling. The catalyst exhibited excellent reusability, structural integrity, and retained activity in natural organic matter-rich and river water matrices. This work establishes a foundational platform for high-loading cobalt borates immobilized on fibrous supports, offering a scalable and robust solution for the catalytic degradation of emerging contaminants via sulfate radical-based AOPs. The persistent release of organic pollutants like pharmaceuticals into water bodies poses significant environmental challenges, as conventional wastewater treatments often fall short in degrading these substances. This study explores the development of cobalt pyroborate catalysts supported on dendritic fibrous silica (KCC-1) for advanced oxidation processes (AOPs). The authors employed both one-pot hydrothermal and post-synthetic impregnation methods to synthesize Co₂B₂O₅@KCC-1 catalysts, varying Si/Co and B/Co molar ratios to optimize phase composition and morphology. The optimized catalyst demonstrated superior degradation of pollutants such as 4-nitrophenol, tetracycline, and sulfamethoxazole, attributed to the formation of phase-pure Co₂B₂O₅ with favorable redox properties. The study highlights the catalyst’s high reusability and stability, suggesting its potential for practical wastewater treatment applications. Future work could focus on further enhancing the catalyst’s performance and reducing cobalt leaching. This summary was initially drafted using artificial intelligence, then revised and fact-checked by the author. High-loading Co₂B₂O₅ supported on dendritic fibrous KCC-1 exhibits enhanced catalytic performance by integrating favorable Co₂B₂O₅ redox chemistry with accessible active-site dispersion and efficient mass transport. The Co(II)/Co(III) redox cycle promotes PMS activation and reactive oxygen species generation for the degradation of diverse organic pollutants. Comparative studies with MCM-41-supported and low-loading catalysts demonstrate that catalytic performance is governed by the combined effects of active-phase identity, cobalt loading, spatial distribution, and support architecture rather than surface area alone.
The isolation of graphene monolayer has ignited a surge of exploration into two-dimensional materials, unveiling unprecedented opportunities to control matter at atomic precision. Among these emerging families, polymeric carbon nitride (CxNy) stands out by bridging molecular tunability with semiconductor functionality. The nitrogen-rich framework further stabilizes metal atoms as atomically dispersed catalytic centers, transforming CxNy from a passive support into an electronically interactive participant in catalytic reactions. This perspective highlights recent advances in atomic-site engineering within CxNy frameworks, emphasizing how the interplay between coordination chemistry, electronic structure, and charge dynamics governs photocatalytic activity and selectivity. Finally, we discuss emerging principles of metal-support interactions and outline future directions toward programmable single-atom catalysts that unify structural, electronic, and functional precision within the CxNy structures. Polymeric carbon nitride (CxNy) stands out in the realm of two-dimensional materials for its tunable structure and electronic properties, making it a promising candidate for photocatalysis. This study explores how atomic-site modulation, particularly through metal-site engineering, enhances the photocatalytic efficiency of CxNy. They highlight that metal atoms anchored within the nitrogen-rich framework of CxNy improve light absorption and charge separation, leading to enhanced photocatalytic activity. Notably, single-atom catalysts within CxNy show superior performance in hydrogen evolution and other reactions due to precise control over electronic states and catalytic sites. This work highlights the potential of CxNy as a versatile platform for sustainable photocatalysis and suggests future directions.“This summary was initially drafted using artificial intelligence, then revised and fact-checked by the author.” Polymeric carbon nitride serves as a programmable platform for sustainable photocatalysis. Its nitrogen-rich framework stabilizes atomically dispersed metal centers, transforming it from a passive support into an electronically interactive participant. This Perspective highlights recent advances in atomic-site engineering within carbon nitride frameworks, emphasizing how atomic-scale regulation of the spatial microenvironment allows for precise control over electronic structure and charge dynamics. Finally, we discuss emerging principles of metal-support interactions and outline future directions toward programmable single-atom catalysts that offer a pathway toward efficient, durable, and selective solar-driven reactions.
Porous honeycomb architectures based on TEMPO-oxidized cellulose nanofibers (CNF) have been extensively explored in filtration, separation, and energy-related applications, where directional transport and mechanical stability are essential. While it remains to be studied to translate these structurally efficient architectures into tissue engineering applications, which is challenging due to the stringent requirements for aqueous stability, biocompatibility, and tissue-relevant mechanics. Here, we report a conceptual transition of CNF honeycomb materials from transport-oriented functional media to biologically active, mechanically compliant scaffolds for soft tissue regeneration. Using unidirectional freeze-drying, we fabricated aligned honeycomb scaffolds composed of TEMPO-oxidized CNF, atelocollagen (AC), and β-tricalcium phosphate (TP). This ternary design integrates the structural integrity and anisotropic templating capability of CNF with the bioactivity of AC and the stiffness modulation provided by TP. The optimized scaffold exhibits a highly ordered honeycomb channel architecture with an average channel size of approximately 70 μm, excellent aqueous stability, and soft-tissue-relevant mechanical properties. In vitro studies using C2C12 myoblasts demonstrate not only high cytocompatibility but also efficient cell infiltration depth and promoted myogenic differentiation along the aligned channels, when compared with the random porous control sample. The proposed CNF-based honeycomb scaffold serves as a versatile platform for aligned soft tissue engineering, like skeletal muscle and potentially biologically integrated bioreactor systems that meet the functional demands of regenerative medicine. Porous materials have long been pivotal in biomedical research, particularly as scaffolds for tissue regeneration due to their high surface area and tunable porosity. This study addresses the challenge of creating mechanically robust, biocompatible scaffolds with aligned pore structures using cellulose nanofibers (CNF), atelocollagen (AC), and tricalcium phosphate (TP). The authors employed unidirectional freeze-drying to fabricate a CNF-AC-TP scaffold with honeycomb channels, optimizing freezing conditions to achieve uniform pore sizes. The scaffold demonstrated enhanced mechanical stability and water resistance, crucial for soft tissue applications. It supported C2C12 myoblast cell adhesion, infiltration, and differentiation, indicating its potential for muscle tissue engineering. The study advances scaffold design by integrating structural, mechanical, and biological functionalities, suggesting future exploration into vascularization and in vivo applications. This work establishes a foundation for developing multifunctional scaffolds for regenerative medicine. This summary was initially drafted using artificial intelligence, then revised and fact-checked by the author. Anisotropic honeycomb scaffolds composed of TEMPO-oxidized cellulose nanofibers, atelocollagen, and β-tricalcium phosphate were fabricated by unidirectional freeze-drying for soft tissue engineering. The optimized scaffold exhibited highly aligned honeycomb channels, excellent aqueous stability, and soft tissue-relevant mechanical properties. Compared with random porous scaffolds, it significantly enhanced C2C12 myoblast infiltration and promoted aligned myogenic differentiation. This work demonstrates a conceptual transition of CNF honeycomb materials to biologically active scaffolds, providing a versatile platform for skeletal muscle regeneration and other aligned soft tissue engineering applications.
