Skip to main content
Start main content

News

News

HKU Chair Professor Xuhua HE Elected Vice President of the International Mathematical Union

Professor Xuhua HE, Chair Professor in the Department of Mathematics under the Faculty of Science at The University of Hong Kong (HKU), has been elected Vice President of the International Mathematical Union (IMU). At 47, Professor He is the youngest Vice-President to join the Union’s leadership in nearly two decades, and only the second Chinese mathematician to hold this prestigious position since the IMU’s inception. The appointment was formally announced on 21 July at the IMU General Assembly in New York, USA. The IMU is the premier global authority in mathematics. A member of the International Science Council, its membership comprises mathematics organisations from more than 80 countries and regions. The IMU organises the quadrennial International Congress of Mathematicians (ICM) and adjudicates the highest accolades in mathematics, including the Fields Medal. In his role on the IMU’s core Executive Committee, the Vice-President will be instrumental in shaping global strategies for mathematical development, while overseeing the organisation of the ICM and the selection of major international awards. Professor Xiang ZHANG, President and Vice-Chancellor of HKU, extended his warmest congratulations, “Pure mathematics is the very soul of technological innovation. With the recent arrival of several world-class scholars, including a Fields Medallist, our Department of Mathematics is rapidly cementing its position as a world-class mathematical centre. Professor He’s election underscores the leading academic strength of Hong Kong and the nation on the global stage, whilst igniting the aspirations of young scholars. We trust this historic milestone will inspire a new generation of scientists to venture fearlessly into the unknown and reach new heights in global academia.” Professor He is an internationally acclaimed leader in Lie theory, arithmetic geometry, and representation theory. In 2013, he was awarded the Morningside Gold Medal of Mathematics, widely regarded as the “Chinese Fields Medal”. He was an invited sectional speaker at the ICM in 2018, and in 2022 received the Chevalley Prize in Lie Theory—the field’s highest international honour—becoming the only mathematician based in China to date to achieve this distinction. Professor He also serves as the President of the Hong Kong Mathematical Society and is a Fellow of The Hong Kong Academy of Sciences. As a leading figure in modern mathematics, Professor He displayed extraordinary talent from an early age. Born in Chongqing in 1979, he first rose to prominence in 1996 by winning a gold medal for China at the International Mathematical Olympiad (IMO). He went on to pursue his studies at Peking University and the Massachusetts Institute of Technology (MIT). Dedicated to tackling the most challenging, frontier conjectures in pure mathematics, Professor He has made systematic and highly original breakthroughs in the areas of Shimura varieties and Hecke algebras, and in the work on Serre’s conjecture II and Lusztig’s positivity conjecture on the of canonical bases. Expressing his gratitude, Professor He said, “I am deeply honoured to be elected Vice President of the International Mathematical Union. This is not only a personal milestone but, more importantly, a reflection of how the global mathematical community recognises the vibrant growth of research in China. Moving forward, I hope to actively champion open collaboration and academic exchange globally, bringing our mathematical achievements to the world stage while creating broader international opportunities for Chinese mathematicians.”

NEWS DETAIL

Image modified from Lu et al., Nat. Photon. (2026).

HKU MILES-Shenzhen Pioneers Novel Super-Inert Fluorescent Dye For Clearer Ureter Imaging during Surgical Navigation

A cross-disciplinary research team led by Professor Hongjie DAI, Director of The Materials Institute of Life Sciences and Energy (MILES) of The University of Hong Kong (HKU) in Shenzhen, has developed a promising near-infrared (NIR) fluorescent dye for potential clinical application in ureter imaging during surgical navigation. The novel dye, named SID-788, exhibits excellent biocompatibility and superior ureter imaging performance, enabling clear ureter visualisation for at least four to five hours in a porcine model using clinical NIR laparoscopes and robotic surgical systems, a duration sufficient for most abdominopelvic surgical procedures. Professor Dai is a Sapientia Eminence Professor and Chair Professor in the Department of Chemistry, the Department of Mechanical Engineering and the School of Biomedical Sciences. The study was conducted in collaboration with The University of Hong Kong-Shenzhen Hospital and Peking University First Hospital. Challenges of traditional NIR fluorescent dyes for ureter imaging during surgical navigation Clear visualisation of ureters is critical for avoiding injury during abdominopelvic surgery and for treating ureteral stenosis or obstruction. This requires fluorescent dyes that are highly water-soluble, safe for patients, show minimal unwanted binding to blood proteins or tissues, and are cleared almost entirely through the kidneys, achieving nearly complete renal excretion. Many strategies have been explored to improve NIR fluorescent dyes for surgical imaging. For example, a benchmark NIR dye IRDye800CW containing multiple charged groups has been extensively investigated in clinical trials. However, IRDye800CW has several limitations, including poor photostability, non-specific binding to proteins or tissues, and clearance through both biliary and renal pathways, which may reduce its specificity for highlighting the urinary system. Zwitterionic ZW800 improves renal clearance, but its chemical stability and photostability are low. Therefore, there remains an urgent need to develop new NIR dyes that combine exceptional aqueous solubility, biocompatibility and stability with high imaging performance for clinical applications. Super-Inert Near-Infrared Fluorescent Rotaxane Dye Figure 1. Top left: Structure of the super-inert near-infrared fluorescent rotaxane dye SID-788. Top middle: SID-788 is safe for overdosage injection (500-fold of imaging dose) and exhibits efficient and ~100% renal excretion. Top right: NIR-II imaging in murine model. Principal component analysis (PCA) of NIR-II video (5–40 s post-injection) reveals haemodynamics in various vessels and organs. Bottom: Schematic diagram of surgical imaging workflow in porcine model. Image modified from Lu et al., Nat. Photon. (2026).   Led by Professor Dai, this work innovated a near-neutral cyanine dye by threading it through an α-cyclodextrin ring, essentially dressing up the dye with a highly biocompatible α-cyclodextrin “cloth” to impart excellent aqueous solubility (~29 mg ml−1) and super-inertness, i.e., exhibiting negligible binding and retention by serum proteins, organs and tissues. The dye undergoes complete renal excretion in its original form within hours after administration and exhibits superior stability in physiological conditions. The resulting super-inert dye (SID), named SID-788, enables high-performance ureter imaging in mice and pigs using NIR-II (1000-3000 nm) wide-field and clinically approved NIR-I (800-1000 nm) laparoscopes and robotic surgical systems. Further, owing to the cyclodextrin ring protection of the dye backbone against chemical attacks, SID-788 exhibited superior chemical and photostability compared with existing NIR dyes. This work established that threading dye molecules through cyclodextrin provides a versatile strategy for engineering fluorescent probes with excellent biocompatibility, brightness and stability. In preclinical studies, SID-788 was well tolerated in mice at doses up to 500 times the standard imaging dose (0.5 mg kg−1), paving the way for its potential clinical translation. Professor Hongjie Dai commented, “Wrapping a molecule with a human-compatible cyclodextrin ring is exciting in the NIR dye field. The development of SID-788 serves as a compelling example of integrating fundamental innovation with translational research. Through its novel molecular design, SID-788 possesses properties long pursued in the NIR fluorescent dye field, solving some long-standing problems in this field. More importantly, we have successfully accomplished gram-scale synthesis in our laboratory and are currently partnering with a CRO to advance toward kilogram-scale production for clinical translation.” This study is supported by the Materials Institute of Life Sciences and Energy (MILES) in Shenzhen, Hong Kong’s Academic and Industry Sectors One-plus Scheme (RAISe+) and the JC STEM Lab of Nanoscience. The team’s findings have been published in Nature Photonics. The research team comprises the following HKU academics: Professor Hongjie Dai, Sapientia Eminence Professor and Chair Professor, Department of Chemistry, Faculty of Science; Department of Mechanical Engineering, Faculty of Engineering; School of Biomedical Sciences, LKS Faculty of Medicine; and Materials Institute of Life Sciences and Energy (MILES), HKU. Professor Kenneth Man-Chee Cheung, Jessie Ho Professor in Spine Surgery and Chair Professor, Department of Orthopaedics and Traumatology, and The University of Hong Kong-Shenzhen Hospital, HKU. Professor Feifei Wang, Assistant Professor, Department of Electrical and Electronic Engineering, Faculty of Engineering, and Materials Institute of Life Sciences and Energy (MILES), HKU. For more details, please refer to the journal paper “A super-inert near-infrared fluorescent rotaxane dye for surgical navigation” published in Nature Photonics. 

NEWS DETAIL

Researchers found that the city’s population retains high genetic diversity despite its small size, highlighting its potential conservation value. Image credit: Uva FUNG

HKU Biologists Reveal How Neural Circuits Use Backup Mechanisms to Protect Essential Survival Reflexes

A research team led by Professor Chaogu ZHENG from the School of Biological Sciences at The University of Hong Kong (HKU), in collaboration with scientists from Princeton University and Columbia University, has discovered how sensory-motor circuits—nerve circuits that turn sensory signals into reflex actions—remain reliable even when some genes or neural connections are disrupted. Using the gentle touch reflex of the nematode Caenorhabditis elegans (C. elegans) as a model, the team found that this essential survival response is not controlled by a single biological component. Instead, it is supported by several overlapping mechanisms, including existing alternative neural pathways and molecular components that enable neurons to send and receive signals. These layers of genetic redundancy help maintain the touch response and improve the animal’s ability to escape from predators. The findings were recently published in the Proceedings of the National Academy of Sciences (PNAS). Research Background Reflex actions are among the most basic and important functions of the nervous system. When an animal senses danger, sensory neurons detect the stimulus and pass the signal through synapses, the contact points where neurons communicate, to downstream neurons that control movement. The gentle touch circuit of C. elegans is a classic model in neuroscience. Its cellular wiring was mapped at single-cell resolution about 40 years ago, showing how sensory neurons, interneurons, and motor neurons are connected in the reflex pathway. However, the molecular details of how these neurons communicate, and how this communication supports a reliable reflex response, were not fully understood. To address this question, the team examined synapses in the gentle touch reflex circuit and mapped the molecular mechanisms that allow signals to pass from sensory neurons to downstream neurons. Key Findings Through genetic screens and follow-up analyses, the team found that the touch reflex circuit is protected by several layers of genetic redundancy. These mechanisms operate at different levels, including individual genes, synapses, and neural pathways. In the posterior touch circuit, two gap junction proteins help connect sensory neurons with interneurons. Either protein alone is sufficient to maintain the connection, so losing either does not disrupt the touch response. In the anterior touch circuit, the team found another form of redundancy: two neural pathways can both support the backward movement triggered by touch. Blocking either pathway alone does not stop the motor response, indicating that the circuit can continue to function through an alternative existing route. The team also found that these redundant components are not simply spare parts. Some synaptic genes may not be essential for initiating the touch response, but they still affect how strong and effective it is. For example, removing one gene may not stop the animal from moving backwards after being touched, but it can shorten the reversal distance and make the animal less likely to turn afterwards. This weaker response reduces its ability to escape from carnivorous nematodes. These findings show that redundancy in the nervous system serves two purposes: it helps prevent an essential reflex from failing, and it strengthens the escape response. Image 2. Redundant mechanisms supporting the gentle touch reflex in C. elegans.The diagram shows how genes, synapses and neural pathways work together to maintain a reliable touch response.   Implications The study provides new insight into how nervous systems protect essential behaviours. It shows that robust neural circuits can be built through overlapping genes, synapses, and neural pathways, so that the loss of one component does not necessarily stop the behaviour. The corresponding author, Professor Chaogu ZHENG of the HKU School of Biological Sciences, explains, “From an evolutionary perspective, the findings suggest that components which appear redundant in a standard laboratory test may still be preserved because they improve survival in real-life situations, such as escaping from predators. In this way, redundancy is not merely a backup system, but part of how neural circuits produce reliable and effective behaviour.” For more details, please refer to the journal paper “Synaptic and neural pathway redundancy enables the robustness of a sensory-motor reflex and promotes predation escape in Caenorhabditis elegans” published in the Proceedings of the National Academy of Sciences (PNAS).  

NEWS DETAIL

Filter by

HKU Chair Professor Xuhua HE Elected Vice President of the International Mathematical Union

Professor Xuhua HE, Chair Professor in the Department of Mathematics under the Faculty of Science at The University of Hong Kong (HKU), has been elected Vice President of the International Mathematical Union (IMU). At 47, Professor He is the youngest Vice-President to join the Union’s leadership in nearly two decades, and only the second Chinese mathematician to hold this prestigious position since the IMU’s inception. The appointment was formally announced on 21 July at the IMU General Assembly in New York, USA. The IMU is the premier global authority in mathematics. A member of the International Science Council, its membership comprises mathematics organisations from more than 80 countries and regions. The IMU organises the quadrennial International Congress of Mathematicians (ICM) and adjudicates the highest accolades in mathematics, including the Fields Medal. In his role on the IMU’s core Executive Committee, the Vice-President will be instrumental in shaping global strategies for mathematical development, while overseeing the organisation of the ICM and the selection of major international awards. Professor Xiang ZHANG, President and Vice-Chancellor of HKU, extended his warmest congratulations, “Pure mathematics is the very soul of technological innovation. With the recent arrival of several world-class scholars, including a Fields Medallist, our Department of Mathematics is rapidly cementing its position as a world-class mathematical centre. Professor He’s election underscores the leading academic strength of Hong Kong and the nation on the global stage, whilst igniting the aspirations of young scholars. We trust this historic milestone will inspire a new generation of scientists to venture fearlessly into the unknown and reach new heights in global academia.” Professor He is an internationally acclaimed leader in Lie theory, arithmetic geometry, and representation theory. In 2013, he was awarded the Morningside Gold Medal of Mathematics, widely regarded as the “Chinese Fields Medal”. He was an invited sectional speaker at the ICM in 2018, and in 2022 received the Chevalley Prize in Lie Theory—the field’s highest international honour—becoming the only mathematician based in China to date to achieve this distinction. Professor He also serves as the President of the Hong Kong Mathematical Society and is a Fellow of The Hong Kong Academy of Sciences. As a leading figure in modern mathematics, Professor He displayed extraordinary talent from an early age. Born in Chongqing in 1979, he first rose to prominence in 1996 by winning a gold medal for China at the International Mathematical Olympiad (IMO). He went on to pursue his studies at Peking University and the Massachusetts Institute of Technology (MIT). Dedicated to tackling the most challenging, frontier conjectures in pure mathematics, Professor He has made systematic and highly original breakthroughs in the areas of Shimura varieties and Hecke algebras, and in the work on Serre’s conjecture II and Lusztig’s positivity conjecture on the of canonical bases. Expressing his gratitude, Professor He said, “I am deeply honoured to be elected Vice President of the International Mathematical Union. This is not only a personal milestone but, more importantly, a reflection of how the global mathematical community recognises the vibrant growth of research in China. Moving forward, I hope to actively champion open collaboration and academic exchange globally, bringing our mathematical achievements to the world stage while creating broader international opportunities for Chinese mathematicians.”

NEWS DETAIL

HKU Astrophysicist Lixin DAI Named RGC Research Fellow for Pioneering Black Hole Research

Professor Lixin DAI in the Department of Physics has been honoured under the Research Grants Council’s Research Fellow Scheme for the 2026/27 academic year. Her awarded project, “Modelling Super-Eddington Accretion Physics from Cosmic Dawn Quasars to Gravitational-Wave Counterparts,” seeks to develop a unified framework for understanding how black holes consume matter beyond the theoretical Eddington limit. According to classical physics, radiation pressure should prevent matter from continuing to fall into a black hole once this limit is reached. However, astronomical observations suggest that black holes frequently exceed it, powering extreme phenomena such as tidal disruption events, binary black hole mergers in active galactic nucleus disks, and the recently discovered “Little Red Dots” in the early universe. Professor Dai’s team will use advanced general relativistic magnetohydrodynamic simulations and radiative-transfer calculations to investigate these processes and predict their observable signatures across different wavelengths. The findings will support observations by major international space missions, including the James Webb Space Telescope and the Einstein Probe. The project will advance understanding of black hole growth and energetic cosmic events, while strengthening Hong Kong’s position as an international centre for black hole astrophysics.  

NEWS DETAIL

HKU Physicists Draw on Pride and Prejudice to Break Down Barriers in Quantum Magnetism

Professor Zi Yang MENG from the HKU Department of Physics and the State Key Laboratory of Optical Quantum Materials, together with Professor Cristian D. BATISTA (University of Tennessee) and Professor Shiliang LI (Institute of Physics, Chinese Academy of Sciences), have recently published an invited Perspective in Nature Physics. Titled “An integrated theoretical and numerical approach to understand modern experiments on quantum magnetism”, the article advocates closer and more equal collaboration among three major pillars of quantum many-body physics: analytical theory, numerical simulation and experimental materials science. Drawing inspiration from Jane Austen’s Pride and Prejudice, the authors examine how disciplinary divisions may hinder scientific progress. In the quest to decipher extreme states of matter, such as quantum spin liquids and complex phase transitions, the field has traditionally treated its three core pillars as fragmented entities. Over the years, the authors observed a prevailing attitude among theorists and computational physicists—particularly pronounced within the theoretical community—where one’s own sub-discipline is viewed as the primary driver of truth, while the others are diminished as mere auxiliary tools to validate one's own cleverness. Researchers can sometimes regard their own specialism as the main source of scientific insight while treating other approaches primarily as supporting or verification tools. The authors argue that overcoming these attitudes is essential for addressing increasingly complex problems in quantum magnetism. “This reflects a very human flaw, perfectly captured by Jane Austen,” Professor Meng noted. “Theorists often harbour an elitist ‘pride’, believing that analytical field theories dictate the entire scientific narrative. Meanwhile, numerical and materials experts hold defensive ‘prejudices’, dismissing theoretical constructs as castles in the air. This traditional paradigm, which treats related disciplines as subservient tools, severely hinders progress in our field. These three pillars must operate on equal footing as an inseparable trinity. Only by embracing this integrated approach can we truly advance our understanding of quantum magnetism.” Bringing Different Approaches Together The Perspective draws on several studies to demonstrate how this integrated approach works in practice. Quantum magnetic materials are often too complex to be understood through any single method. Analytical theory proposes possible explanations, numerical simulations test them under different conditions, while experiments determine whether the predictions reflect the behaviour of real materials. To champion this holistic framework, the authors showcase three major core systems where they have actively implemented this integrated approach in recent years, chronicling the field's historical progress and the leap from low to high dimensions: The Chasm from 1D to 2D (Luttinger Liquids to Triangular Quantum Ising Magnets): The neutron scattering spectra of one-dimensional magnetic materials can be perfectly reproduced by fusing analytical Luttinger theory with numerical Density Matrix Renormalisation Group (DMRG) simulations, both yielding flawless agreement with experimental spectra. Operating under their proposed collective paradigm, the team utilised sign-problem-free, large-scale Quantum Monte Carlo (QMC) and thermal Tensor Renormalisation Group (TRG) calculations to precisely map the microscopic parameters of the 2D magnet TmMgGaO₄. This successfully predicted and experimentally verified the elusive Berezinskii-Kosterlitz-Thouless (BKT) phase in a challenging 2D quantum Ising model. [See the HKU press release] Phase Diagrams of Triangular Lattice Heisenberg Magnets: This section highlights breakthrough quantum spin liquid (QSL) materials. The article tracks the domain's evolution from the 120° magnetically ordered Ba₃CoSb₂O₉ to the genuine J₁-J₂ quantum spin liquid behaviours observed in KYbSe₂ and NaYbSe₂. This milestone was reached by seamlessly combining advanced many-body numerical modelling with the Schwinger boson theoretical framework pioneered by Professor Batista and collaborators, as well as material synthesis and characterisation, exemplifying an egalitarian alliance between theory and materials. The Historical Evolution of Kagome Lattice Heisenberg Magnets: Offering an expanded and detailed retrospective, the article reviews the domain's journey from early models like Herbertsmithite (described by a homogeneous antiferromagnetic Heisenberg model) to the recent breakthroughs in the 3J model calculation and experiment represented by YCu_3(OH)_6Br_2[Br_{1-x}(OH)_x]. Building upon HKU's 2024 breakthrough on this material—where the experimental team painstakingly co-aligned over 5,000 single crystals to secure neutron scattering data and observed the computed Dirac quantum spin liquid spectrum. Comparing the resulting data with numerical calculations provided evidence consistent with the predicted behaviour of a Dirac quantum spin liquid. Looking Ahead The authors believe this integrated approach will be essential for investigating other challenging systems, including Kitaev materials and novel quantum spin liquids. Combining theoretical models, advanced simulations, machine learning and experiments could help researchers discover and understand new quantum states and materials. Developed through extensive discussion and editorial refinement over nearly two years, the Perspective retains its central message that analytical theory and numerical simulation should stand as equal partners alongside experiments in addressing the complex challenges of quantum magnetism. Professor Meng hopes that this vision will resonate with researchers and students across the quantum many-body physics community and encourage closer, more integrated collaboration in the field. This work was supported by the high-performance computing platforms of HKU Information Technology Services, the “Blackbody” supercomputer cluster in the HKU Department of Physics, and computational resources from Beijing PARATERA Tech CO., Ltd., with funding from the Research Grants Council (RGC) of Hong Kong.

NEWS DETAIL

HKU Chemists Create New Carbon-Based Material for Future Sensors and Flexible Electronics

A research team led by Professors David Lee PHILLIPS and Seungkyu LEE of the Department of Chemistry at The University of Hong Kong (HKU) has developed a new two-dimensional carbon-based material, offering a strategy for building stable, ordered molecular frameworks for advanced technologies. The material, named HKU-50, belongs to a class of materials known as covalent organic frameworks, or COFs. These materials are built from molecular units that connect into regular, repeating structures. HKU-50 is distinctive because its framework is made entirely from carbon and hydrogen, forming an ordered hydrocarbon structure with long-range crystallinity. Creating such ordered all-carbon frameworks has long been impossible. Carbon–carbon bonds are strong and stable, but this also means that once molecules connect in the wrong way during synthesis, they are difficult to rearrange. As a result, scientists often obtain a disordered network, whose properties are harder to control, rather than a well-ordered crystalline material with clearer and more useful functions. The HKU team overcame this challenge using a reaction known as olefin metathesis, which allows carbon–carbon double bonds to break and reform during synthesis. This reversibility gave the growing framework a chance to correct misplaced connections, helping it assemble into an ordered crystalline structure instead of a disordered network. The resulting HKU-50 showed high thermal and chemical stability. Its ordered structure also significantly improved its light-emitting performance. Compared with the disordered version of the same material, HKU-50 showed a fourfold increase in photoluminescence quantum yield — a measure of how efficiently a material converts absorbed light into emitted light. This suggests that the ordered structure not only makes the material easier to study and control, but also directly enhances its optical properties. The findings provide a new route for constructing crystalline hydrocarbon frameworks, a long-standing challenge in materials chemistry. In the future, such materials may support the development of flexible electronics, chemical sensors and other advanced light-emitting technologies. The study was published in the Journal of the American Chemical Society and highlighted on the journal’s cover, as well as in Chemical & Engineering News.  

NEWS DETAIL

Image modified from Lu et al., Nat. Photon. (2026).

HKU MILES-Shenzhen Pioneers Novel Super-Inert Fluorescent Dye For Clearer Ureter Imaging during Surgical Navigation

A cross-disciplinary research team led by Professor Hongjie DAI, Director of The Materials Institute of Life Sciences and Energy (MILES) of The University of Hong Kong (HKU) in Shenzhen, has developed a promising near-infrared (NIR) fluorescent dye for potential clinical application in ureter imaging during surgical navigation. The novel dye, named SID-788, exhibits excellent biocompatibility and superior ureter imaging performance, enabling clear ureter visualisation for at least four to five hours in a porcine model using clinical NIR laparoscopes and robotic surgical systems, a duration sufficient for most abdominopelvic surgical procedures. Professor Dai is a Sapientia Eminence Professor and Chair Professor in the Department of Chemistry, the Department of Mechanical Engineering and the School of Biomedical Sciences. The study was conducted in collaboration with The University of Hong Kong-Shenzhen Hospital and Peking University First Hospital. Challenges of traditional NIR fluorescent dyes for ureter imaging during surgical navigation Clear visualisation of ureters is critical for avoiding injury during abdominopelvic surgery and for treating ureteral stenosis or obstruction. This requires fluorescent dyes that are highly water-soluble, safe for patients, show minimal unwanted binding to blood proteins or tissues, and are cleared almost entirely through the kidneys, achieving nearly complete renal excretion. Many strategies have been explored to improve NIR fluorescent dyes for surgical imaging. For example, a benchmark NIR dye IRDye800CW containing multiple charged groups has been extensively investigated in clinical trials. However, IRDye800CW has several limitations, including poor photostability, non-specific binding to proteins or tissues, and clearance through both biliary and renal pathways, which may reduce its specificity for highlighting the urinary system. Zwitterionic ZW800 improves renal clearance, but its chemical stability and photostability are low. Therefore, there remains an urgent need to develop new NIR dyes that combine exceptional aqueous solubility, biocompatibility and stability with high imaging performance for clinical applications. Super-Inert Near-Infrared Fluorescent Rotaxane Dye Figure 1. Top left: Structure of the super-inert near-infrared fluorescent rotaxane dye SID-788. Top middle: SID-788 is safe for overdosage injection (500-fold of imaging dose) and exhibits efficient and ~100% renal excretion. Top right: NIR-II imaging in murine model. Principal component analysis (PCA) of NIR-II video (5–40 s post-injection) reveals haemodynamics in various vessels and organs. Bottom: Schematic diagram of surgical imaging workflow in porcine model. Image modified from Lu et al., Nat. Photon. (2026).   Led by Professor Dai, this work innovated a near-neutral cyanine dye by threading it through an α-cyclodextrin ring, essentially dressing up the dye with a highly biocompatible α-cyclodextrin “cloth” to impart excellent aqueous solubility (~29 mg ml−1) and super-inertness, i.e., exhibiting negligible binding and retention by serum proteins, organs and tissues. The dye undergoes complete renal excretion in its original form within hours after administration and exhibits superior stability in physiological conditions. The resulting super-inert dye (SID), named SID-788, enables high-performance ureter imaging in mice and pigs using NIR-II (1000-3000 nm) wide-field and clinically approved NIR-I (800-1000 nm) laparoscopes and robotic surgical systems. Further, owing to the cyclodextrin ring protection of the dye backbone against chemical attacks, SID-788 exhibited superior chemical and photostability compared with existing NIR dyes. This work established that threading dye molecules through cyclodextrin provides a versatile strategy for engineering fluorescent probes with excellent biocompatibility, brightness and stability. In preclinical studies, SID-788 was well tolerated in mice at doses up to 500 times the standard imaging dose (0.5 mg kg−1), paving the way for its potential clinical translation. Professor Hongjie Dai commented, “Wrapping a molecule with a human-compatible cyclodextrin ring is exciting in the NIR dye field. The development of SID-788 serves as a compelling example of integrating fundamental innovation with translational research. Through its novel molecular design, SID-788 possesses properties long pursued in the NIR fluorescent dye field, solving some long-standing problems in this field. More importantly, we have successfully accomplished gram-scale synthesis in our laboratory and are currently partnering with a CRO to advance toward kilogram-scale production for clinical translation.” This study is supported by the Materials Institute of Life Sciences and Energy (MILES) in Shenzhen, Hong Kong’s Academic and Industry Sectors One-plus Scheme (RAISe+) and the JC STEM Lab of Nanoscience. The team’s findings have been published in Nature Photonics. The research team comprises the following HKU academics: Professor Hongjie Dai, Sapientia Eminence Professor and Chair Professor, Department of Chemistry, Faculty of Science; Department of Mechanical Engineering, Faculty of Engineering; School of Biomedical Sciences, LKS Faculty of Medicine; and Materials Institute of Life Sciences and Energy (MILES), HKU. Professor Kenneth Man-Chee Cheung, Jessie Ho Professor in Spine Surgery and Chair Professor, Department of Orthopaedics and Traumatology, and The University of Hong Kong-Shenzhen Hospital, HKU. Professor Feifei Wang, Assistant Professor, Department of Electrical and Electronic Engineering, Faculty of Engineering, and Materials Institute of Life Sciences and Energy (MILES), HKU. For more details, please refer to the journal paper “A super-inert near-infrared fluorescent rotaxane dye for surgical navigation” published in Nature Photonics. 

NEWS DETAIL

Artist’s illustration showing JWST, aided by gravitational-lensing, enabled the team to measure the mass of an inactive black hole in the early Universe. Image credit: Navid Marvi/Carnegie Science.

HKU-HKIAA Astronomer Joins International Study to Weigh Inactive Black Hole Seen 10 Billion Years Ago

An international team of astronomers, including Professor Meng GU, an affiliated member of the Hong Kong Institute for Astronomy and Astrophysics (HKIAA) at The University of Hong Kong (HKU), has directly measured the mass of an inactive supermassive black hole in the early Universe for the first time. The breakthrough opens a new window onto how supermassive black holes and their host galaxies grew together. The study was recently published in Science and was led by Dr Andrew NEWMAN at Carnegie Observatories. Professor Gu, the second author of the paper, was affiliated with the HKU Department of Physics at the time of the research and is now an affiliated member of HKIAA. Black Holes at the Centres of Galaxies Supermassive black holes are thought to lie at the centres of most massive galaxies. Although black holes themselves cannot be seen directly, their presence can be revealed by the way their gravity affects the motion of nearby stars. This same principle led to the discovery of the supermassive black hole at the centre of our own Milky Way, where Reinhard GENZEL and Andrea GHEZ resolved and tracked individual stars to measure its mass with high precision. They shared the 2020 Nobel Prize in Physics for this work. Later studies measured black hole masses from the integrated motions of unresolved stars in nearby galaxies, typically within about 650 million light-years from Earth. Pushing this approach to more distant galaxies, however, is extremely difficult: the region where a black hole’s gravity dominates is very small, making it usually impossible to resolve the sphere of influence across billions of light-years. In this study, the team observed MRG-M0138, a massive galaxy seen as it was about 10 billion years ago, when the Universe was only about one-quarter of its current age. At its centre, they found a dormant supermassive black hole with a mass of around six billion Suns. The black hole is inactive, meaning it is not currently feeding strongly on surrounding gas and therefore does not shine brightly like a quasar. Instead of detecting it through light, the team detected it through gravity: the motions of stars near the galaxy’s centre revealed an enormous, highly concentrated mass, far too compact to be a cluster of stars and best explained by a single supermassive black hole. How the Team Weighed the Black Hole The measurement was made possible by the James Webb Space Telescope and gravitational lensing. A massive foreground galaxy cluster acted as a natural cosmic magnifying glass, magnifying the light of MRG-M0138 by about 30 times. This allowed the team to study the motions of stars near the galaxy’s centre in exceptional detail. The result is surprising because the black hole appears too massive for its host galaxy — but only in one sense. Compared with the galaxy’s bulge mass, the black hole is about 12 times more massive than expected for galaxies in the nearby Universe. Bulge mass refers to the mass of stars in the dense central part of a galaxy. In simple terms, MRG-M0138 had not yet built up enough stars to match such a huge black hole by today’s standards. Yet compared with the galaxy’s stellar velocity dispersion, the black hole looks normal. Stellar velocity dispersion measures how much the stars’ speeds vary, reflecting the depth of the galaxy’s central gravitational potential. Together, these two findings give astronomers an important clue. The black hole and the galaxy's central stellar motions were already in place, while the galaxy still had to build up its stellar mass. In other words, the central engine was already fully grown, but the galaxy around it was still catching up. . Stellar kinematics of MRG-M0138 compared with dynamical models. The prominent central peak in the stellar second velocity moment can only be reproduced when the model includes a black hole of about six billion solar masses; models without a black hole cannot explain the observations. Image adapted from Newman et al., Science 392, 1065–1068 (2026) In the relation between black hole mass and stellar velocity dispersion, MRG-M0138 appears similar to nearby galaxies. However, when compared with the bulge mass, its black hole appears unusually overmassive, about 12 times more massive than expected from the local black hole-bulge mass relation. Image adapted from Newman et al., Science 392, 1065–1068 (2026).   Rethinking How Black Holes and Galaxies Grow The study helps address a major question in astronomy: do supermassive black holes and galaxies grow together in step, or can one mature before the other? This discovery suggests that, at least in some massive galaxies, the black hole and central core may grow rapidly in the early Universe, while the host galaxy continues to build up its stellar mass later, possibly through mergers with other galaxies. By directly weighing a dormant black hole from the early Universe, the team has provided a rare benchmark for testing the growth timeline of black holes and galaxies across cosmic history. The finding also shows that, with JWST and gravitational lensing, astronomers can now study distant inactive black holes that were previously beyond reach. “It is remarkable that we can study a galaxy seen 10 billion years ago in such detail.  This would not be possible without strong gravitational lensing acting like nature's magnifying glass and the power of JWST,” said Professor Meng Gu, now an Assistant Professor in the Department of Astronomy at Tsinghua University. “What excites me most is that we can now extend this direct way of weighing black holes back to such an early phase.” For more details, please refer to the journal paper “A stellar dynamical mass measurement of an inactive black hole at redshift 2” published in Science. 

NEWS DETAIL