Prof. Anderson H. C. Shum

The most significant contribution to the fields of microfluidics and soft matter is to introduce and elucidate possibilities offered by an all-aqueous multiphase system. Traditionally, aqueous two-phase systems have only found applications in extraction of molecules and in green chemical synthesis. Its potential and value as a system for studying novel interfacial phenomena and for novel nanobiomedicine have been largely overlooked. The ultralow interfacial tension of the system has called for new ways to induce formation of uniformly sized droplets in microfluidic devices. The passivity of the interface allows visualization and recording of sound and music on a liquid-liquid interface for the first time (featured in Asian Scientist Newsroom and an arts exhibition by The University of Hong Kong (HKU) University Artists in December 2016). The diffuse interfaces of these aqueous interfaces create new opportunities to assembly particles and macromolecules, such as enzymes, for forming new structures with enhanced bio- & cyto-compatibility, as reported in our 2016 HOT paper and cover article in Journal of Materials Chemistry B. Aqueous phase separation can be taken advantage of to create multishelled droplets, as described in our 2018 cover article in Small. Based on this pioneering works, we have incorporated proteins into our all-aqueous droplets to form a new type of vesicles, which we called “fibrillosomes” in our 2016 Nature Communications paper. By manipulating the proteins and the network that it forms, we also demonstrate the overcoming of the thermodynamically favored coalescence dynamics, and induce division of emulsion droplets, a finding that we published in our 2018 Nature Communications paper. This inspires new way to achieve biomimetic behaviors in droplet-based materials that have potential for a new class of programmable carriers for nanomedicine and drugs. The all-aqueous multiphase system suggests opportunities for new analytical chemistry techniques.

Moreover, the constituent components of the all-aqueous systems, such as the proteins, require microscaled analytical chemical approach to study, due to their availability in small volumes. Variations in the concentrations of these components can lead to phase separation without changing the temperature. This not only allows a phase-separation-based strategy to modify the structures of droplets, possibly mimicking biological droplets, but it also provides an excellent model system for studying the intricate relationships between interfacial phenomena and degree of phase separation. Such aqueous phase separation has been shown to influence cytoplasmic dynamics in biological cells discovered by other researchers (Sanders et al., Nature 2017). Our pioneering works have earned the honors of publishing in Emerging Investigators issues in Lab on a Chip, in Soft Matter by RSC, as well as in Early Career Authors in Langmuir, by ACS. In addition, we also discovered a way to map all three dynamical states (jetting, coiling and whipping) of an electrified liquid jet for the first time. The discovery, reported in our 2018 PNAS paper, provides important insights for applying electrified liquid jets, which finds application in forming nanoparticles and nanofibers for biomedical applications. Moving forward, we focused on the application of droplet microfluidics to develop disruptive medical instrumentation to enable faster and more personalized screening and diagnostics, as demonstrated in proof-of-concept studies in performing immunoassay of C-reactive proteins (Tang et al. Lab Chip, 2016) and in detecting foodborne pathogens using loop-mediated isothermal amplification in droplets (Yuan et al. Analytical Chemistry, 2018). Furthermore, our team has clarified the physical process by which diffusion predominates in the generation of all-aqueous droplets (Physical Review Letters, 2019) and developed a numerical profile-transformation program that allows the engineering of stable flow profiles over a wide range of flow conditions for complex microfluidic environmental prediction and design (Engineering, 2021). We have therefore contributed significant progress in understanding dynamics at aqueous–aqueous interfaces, which helped developing interface-assisted design of artificial cells and cyto-mimetic materials, fabrication of cyto- and bio-compatible microparticles, cell micropatterning, 3D bioprinting, and microfluidic separation of cells and biomolecules (Chemical Society Review, 2020), with great potential in the fields of nano-biomedicine and revolutionary interface research.  

To illustrate with concrete examples, our research findings have been applied in the creation of self-assembling Aquabots (ACS Nano, 2022), a new class of soft robots primarily composed of liquids, used as programmable carriers to deliver nanomedicine and drugs through very narrow channels into larger compartments to self-assemble in performing surgical tasks, then dissembled and detached without damage. Another exemplary product advancement would be our invention of elastomeric TransfOrigami microfluidics with embedded stimulus-responsive materials to accomplish plant-like device responsiveness to temperature, humidity and light (Science Advances, cover article, 2022), that is rarely demonstrated in conventional materials for fabricating microfluidic devices, creating new opportunities for intelligent fluidic systems and biomimetic microfluidic devices. We proposed one-pot approach employing mono-sized nanoparticles to self-assemble nanostructures, and discovered that mono-sized nanoparticles would be non-uniformly distributed in two phases and self-assemble into photonic crystals with two different colors that are highly programmable by regulating the colloidal concentration. Imitation of dual-color patches in nature, such as the Papilio Palinurus butterfly, is believed to inspire functional materials designs in industrial and engineering areas related to camouflage, message delivery, and thermoregulation (Nano Letters, 2022). Besides, our team has also demonstrated, for the first time, an innovative all-aqueous technique to perform enzyme-free RNA cleavage reaction through segregative aqueous phase separation in droplets, suggesting a route to prebiotic compartmentalization during the origin of life (Nature Communications, 2021). On the other hand, our inventions/patents also facilitate early virus detection, treatment of infectious diseases, and preventing future pandemics through ATPS and microfluidics applications: presenting large-scale screening methods for identifying determinants of cell–cell fusion induced by spike protein of SARS-CoV-2 (Nature Biomedical Engineering, 2023); suggesting treatment of dysfunctional condensates in diseases with insights into prebiotic compartmentalization triggered by liquid-liquid phase separation (JACS, 2023); discovering Marangoni transport process that inspires automatic fiber fabrication (Nature Communications, 2022) and proposing new ATPS to reproduce viscoelastic networks for modulating biomolecular condensates in synthetic systems mimicking the origin of life (Advanced Materials, 2022)

Since joining HKU in 2010, I have successfully secured competitive grants as a principal investigator; these include one ECS and ten GRF grants from the Research Grants Council of Hong Kong in the past 9 years, a General Program grant, a Science Fund for Young Scholars and a Major Research Project (as a key co-I) under the National Natural Science Foundation of China (NSFC), a grant funded by the Science and Technology Innovation Commission of Shenzhen Municipality, a tier-3 Innovation and Technology Fund (ITF) and a Guangdong-Hong Kong Scheme (TCFS) ITF, as well as a Health and Medical Research Fund (HMRF) on ophthalmological projects. I am the project coordinator of a Research Impact Fund, and was a co-PI on a Collaborative Research Grant (CRF) project. I have published over 100 refereed journal and conference publications. As of Dec 2022, my publications have led to citations of 9639/6892 and h-index of 53/45 in Google scholars/Web of Science. Our works have been translated vigorously through collaborations with clinicians and industries, including a startup that I co-founded with my former PhD student, while also chairing a taskforce on entrepreneurship to establish a university-wide Techno-Entrepreneurship Core for the commercialization of multidisciplinary engineering innovations across microfluidics, photonics, biotechnologies, etc. through instrumentation via serving as the Managing Director of the Advanced Biomedical Instrumentation Centre. Since joining HKU in December 2010, our group has filed patents for 20 inventions, with 7 of them already licensed. Two patented technology was awarded silver medals in the 46th and 47th International Exhibition of Inventions, Geneva, Switzerland in 2018 and 2019. For the above scientific contributions, I have received recognitions, such as Top 1% Scholars by ISI Essential Science Indicators 2018, New Innovator in IEEE Nanomed 2018, FRSC in 2017, HKU Outstanding Young Researcher Award 2016-17, Early Career Award by HK Research Grants Council in 2012. I was selected to join the Hong Kong Young Academy of Sciences as a founding member in 2018. I and my works have been featured in various newspapers and science news outlets, such as Advanced Science News, Wiley Materials Views, Soft Matter Blog, Harvard SEAS Alumni News, etc. In April 2019, I am featured as an emerging talent by HKU. I also contribute to the community by serving editorial roles, such as associate editor of Biomicrofluidics, editorial board member of Scientific Reports, editorial advisory board member of Lab-on-a-Chip, as well as reviewing papers for over 100 journals, including Nature Nanotechnology, Nature Communications, Advanced Materials and PNAS, as well as organizing scientific meetings, such as symposium in Materials Research Society (MRS) Spring Meeting, International Symposium on Microchemistry and Microsystems (ISMM) 2016, Colloids and Interface Symposium 2019, etc. Former members of the group have also gone on to great success in their careers, for instance, as a co-founder and a project manager in the industries, as postdoc in Georgia Institute of Technology, and as faculty members (associate professor/assistant professor/ lecturer) at universities, such as University of California Santa Barbara (UCSB), Nottingham University (Ningbo), Shenzhen University, and HKU Ophthalmology.