The Hongjie An group is focused broadly on Nanoscience and Nanotechnology, exploring the unique physical properties of novel nanomaterials/nanobubbles/nanodroplets, and looking for applications in nano-catalsysis, renewable energy, semiconductor, biology and medicine.
Welcome to Hongjie An Group website
Gas bubbles are ubiquitous in natural and industrial systems, as easily seen in seawater, whale diving, boiling water, submerging hydrophobic surfaces in a liquid, or simply dropping a droplet into a pool. Studies on nanobubble nucleation and its dynamics are key to understanding the onset of cavitation. Nanobubble technologies is vital for wide applications spanning from aquaculture, froth flotation, surface cleaning, sanitation, and fuel energies as well as being at the heart of much of modern fluid physics, physical chemistry and nanotechnology. At the same time, nanobubbles provide sensitive, selective, clean and easy-to-use biomedicines to the diagnosis and therapeutics of diseases. Nanobubble technologies also provide new emerging technologies for renewable energy generation and storage.
The Hongjie An Group has interests ranging from fundamentals (theory of diffusion on nanobubble/nanodroplet nucleation and dynamics) to applications in biomedicines, environmental engineering, separation of mineral particles, chemical catalysis, and renewable energy. Current work also focuses on fluid mechanics of surface and bulk nanobubbles (including boundary slip and cavitating dynamics), developing nanobubble biomedicines, toxicology of nanobubbes, and single-molecule sensors in biomedicines. We develop bottom-up approaches and new methods to prepare nanomaterials and investigate the kinetics and mechanisms of interfacial reactions at the interfaces of gas/liquid/nanoelectrodes.
The group has an extensive interdisciplinary research background (Nanobubble-X). We have a wide range of interests within dedicated experimental and theoretical subgroups. This website enables you to explore some of our research, our publications (and books) and to see the scientists in, and collaborating with the Group.
Fundamentals
We focus on fundamental studies to get insight into nucleation, dynamics, and stability mechanisms of surface and bulk nanobubbles, bubble-particle interactions, the impact of surface wetting ability on boundary slip and cavitating performance, nucleation and stability of nanodroplets, chemical reations at the interface of solid/gas/liquid, Marangoni effects at nanoscales, microplasma, and sensing in microfluidic channels.
Biomedicines
Gases are important for respiration and metabolism in biosystems. We investigate how nanobubbles interact with DNA, protein, and lipids in vitro and in vivo at molecular and the cellular level. We aim to find out how gases are transported inside a cell and also through cell membranes. We look for practical applications of nanobubble technologies in biomedical engineering toward drug delivery and therapeutics with/without the assistance of radio frequency.
Nanobubble chemistry
Gas consumption and evolution reactions are ubiquitous in natural biosystems and industrial systems. This intrigues us to explore problems of nanobubbles associated with chemistry, i.e. chemical nucleation, nanobubble stability in the chemical environment and response to chemical stimuli like pH change, and the impact of nanobubbles on chemical reactions such as efficiency, reaction rates and selectivity. Our research aims to gain answers to practical problems in chemical reactions that have not yet been solved by far. Can nanobubbles be nucleated in gas evolution chemical reactions in liquids? Can the supply of nanobubble suspensions speed up reaction rates of gas consumption? How does the interface of water/gas influence chemical reactions by blocking the effective area of catalysts or accelerating chemical reaction rates?
Nanomaterials
Engineered nanomaterials can take on unique optical, magnetic, electrical, and other physical/chemical properties. These emergent properties have the potential for great impacts in electronics, medicine, and other fields. Nanomaterial-based nanotechnologies make them promising in applications for developing electron devices, manufacturing, high reactivity, sensing, diagnosis and therapeutics. It is also challenging traditional theory at the nanoscale. Low-dimension materials exhibit remarkable quantum optoelectronic properties, including an indirect-to-direct band gap transition, nonlinear optical susceptibility and valley polarization, which are highly related to their natural structures in the forms of spheres, tubes, and planar membranes. We aim to gain new knowledge and theories, develop novel devices, develop new technologies for clean energies, and improve human living quality and human health.
Grants
2023, ARC Discovery Project, Resolving Surface Nanobubbles as Cavitation Nuclei, DP230100556, $407,907, Lead CI
2023, GSC Equipment Grant, Integrated Quantum Efficiency Measurements System, $109,000, CI
2022, Health Group Seed Grants, Understanding cavitation in medical devices: a novel approach to enhance prosthetic heart valves, $35,600, CI
2022, GSC equipment scheme, Optical Tensiometer Suite, $95,510, CI
2022, GSC Equipment Grant, Integrated N2 Glovebox for Chemical Synthesis & Device Fabrication, $109,000, CI
2020, GSC equipment scheme, Radio Frequency Power Amplifier Suite, $35,000, Lead CI
2019, ARC Future Fellowship, Bulk Nanobubbles: from Fundamentals to Biomedical Applications, FT180100361, $755,336, Sole CI
Selected research outcomes
Dr Hongjie An has published more than 80 papers, including 7 papers in Physical Review Letters, 2 in Nano Letters and 2 in ACS Nano, others in peer-reviewed journals such as JACS, Angew Chem, Langmuir, Biotechnol. Adv., Carbon, Eviron. Sci. Technol., JCIS, ect. which have attracted a total citation of more than 3,350 times, with an H-index of 35.
Nanobubbles
Tan B., An H.*, Ohl CD., Body forces drive the apparent line tension of sessile droplets. Phys. Rev. Lett. 130, 064003, 2023.
Hansen HHWB, Cha H., Ouyang L., Zhang J., Jin B., Stratton H., Nguyen N-T., An H., Nanobubble technologies: Applications in therapy from molecular to cellular level. Biotechnol. Adv. 108091, 2023.
Tan B., An H.*, Ohl CD., Comment on “Universal Gas Adsorption Mechanism for Flat Nanobubble Morphologies”, Phys. Rev. Lett. 129: 099601, 2022.
Zeng Q., An H.*, Ohl CD., Wall shear stress from jetting cavitation bubbles: influence of the stand-off distance and liquid viscosity. J. Fluid Mech., 932: A14, 2022
Tan B., Ohl CD., An H.*, Transient solubility gradients mediate oversaturation during solvent exchange. Phys. Rev. Lett. 126: 234502,2021.
Tan B., An H.*, Ohl CD., Identifying surface attached nanobubbles, Curr. Opin. Colloid Interface Sci. 53: 101429, 2021.
Tan B., An H., Ohl CD., Stability of surface and bulk nanobubbles, Curr. Opin. Colloid Interface Sci. 53: 101428, 2021.
Zhou R., Zhou R., Alam D., Zhang T., Li W., Xia Y., An H., Ostrikov K., Plasmacatalytic bubbles using CeO2 for organic pollutant degradation. Chem. Eng. J., 403: 126413, 2021
Tan B., An H.*, Ohl CD.*, How bulk nanobubbles might survive. Phys. Rev. Lett. 124: 134503, 2020.
Tan B., An H.*, Ohl CD., Stability, dynamics, and tolerance to undersaturation of surface nanobubbles. Phys. Rev. Lett. 122: 134502, 2019
Tan B., An H.*, Ohl CD., Surface nanobubbles are stabilised by hydrophobic attraction. Phys. Rev. Lett. 120: 164502, 2018.
Tan B., An H.*, Ohl CD., Resolving the pinning force of nanobubbles with optical microscopy. Phys. Rev. Lett. 118: 054501, 2017.
An H.*, Tan B., Ohl D., Distinguishing nanobubbles from nanodroplets with AFM: the influence of vertical and lateral imaging forces. Langmuir. 32: 12710-12715, 2016.
An H., Tan B., Zeng Q., Ohl D., Stability of Nanobubbles Formed at the Interface between Cold Water and Hot Highly Oriented Pyrolytic Graphite. Langmuir. 32: 11212-11220, 2016.
Zhu J., An H., Alheshibri M., Liu L., Terpstra P., Liu G., Craig S.J.V., Cleaning with bulk nanobubbles. Langmuir. 32: 11203–11211, 2016.
An H., Liu G., Craig S.J.V., Surface Nanobubbles in Nonaqueous Media: Looking for Nanobubbles in DMSO, Formamide, Propylene Carbonate, Ethylammonium Nitrate, and Propylammonium Nitrate. ACS Nano. 9: 7596–7607, 2015.
An H., Liu G., Craig S.J.V., Wetting of nanophases: Nanobubbles, nanodroplets and micropancakes on hydrophobic surfaces. Adv. Colloid Interface Sci. 222: 9-17, 2015.
German S., Wu X., An H., Craig S.J.V., Mega T., Zhang X., Interfacial Nanobubbles Are Leaky: Permeability of the Gas/Water Interface. ACS Nano. 8: 6193-6201, 2014.
Microfluidic Channels
Dai Y, Cha H, Nguyen N-K, Ouyang L, Galogahi F, Yadav AS, An H, Zhang J, Ooi CH, Nguyen N-T., Dynamic Behaviours of Monodisperse Double Emulsion Formation in a Tri-Axial Capillary Device. Micromachines13:1877, 2022
Dai Y, Cha H, Simmonds MJ, Fallahi H, An H, Ta HT, Nguyen NT, Zhang J, McNamee AP., Enhanced Blood Plasma Extraction Utilising Viscoelastic Effects in a Serpentine Microchannel. Biosensors12:120, 2022
Cha H., Fallahi H., Dai Y., Yadav S., Hettiarachchi S., Antony McNamee A., An H., Nan Xiang, Nguyen N-T, Zhang J., Tuning particle inertial separation in sinusoidal channels by embedding periodic obstacle microstructures. Lab Chip, 22: 2789-2800, 2022
Cha H., Fallahi H., Dai Y., Yuan D., An H., Nguyen N-T, Zhang J., Multiphysics microfluidics for cell manipulation and separation: a review. Lab Chip, 22: 423-444, 2022
Galogahi FM, Ansari A, Teo AJT, Cha H, An H, Nguyen N-T., Fabrication and characterization of core-shell microparticles containing an aqueous core. Biomed Microdevices 24:40, 2022
Ren H., Zhu Z., Xiang N., Wang H., Zheng T., An H., Nguyen NT., Zhang J., Multiplexed serpentine microchannels for high-throughput sorting of disseminated tumor cells from malignant pleural effusion. Sens. Actuator B-Chem., 337: 129758, 2021.
Yuan D, Yadav S, Ta H, Fallahi H, An H, Kashaninejad N, Ooi CH, Nguyen N-T, Zhang J., Investigation of viscoelastic focusing of particles and cells in a zigzag microchannel. Electrophoresis 42: 2230–2237, 2021
Galogahi FM, An H., Nguyen, N., Core-shell microparticles: generation approaches and applications, J. Sci.-Adv. Mater. Dev. 5: 417-435, 2020.
Zhang, J., Chintalaramula, N., Vadivelu R., An H., Yuan D., Jin J., Ooi CH., Cock IE., Li W., Nguyen NT., Inertial microfluidic purification of floating cancer cells for drug screening and three-dimensional tumour models. Anal. Chem. 92: 11558–11564, 2020.
Liu N., Xu J., An H., Phan D., Hasimoto M., and Lew W. Direct Spraying Method for Fabrication of Paper-based Microfluidic Devices. J. Micromech. Microeng. 27: 104001, 2017.
Nanomaterials
Tan B., Zhang J., Jin J., Ooi C., He Y., Zhou R., Ostrikov K., Nguyen N., An H.* Direct Measurement of the Contents, Thickness, and Internal Pressure of Molybdenum Disulfide Nanoblisters. Nano Lett. 20: 3478-3484, 2020.
Li R., An H., Huang W., He Y. Molybdenum oxide nanosheets meet ascorbic acid: Tunable surface plasmon resonance and visual colorimetric detection at room temperature. Sens. Actuator B-Chem. 258: 59–63, 2018.
An H.*, Moo. G.J., Tan B.H., Liu S., Pumera M., Ohl CD. Etched nanoholes in graphitic surfaces for enhanced electrochemistry of basal plane. Carbon 123: 84-92, 2017.
An H.*, Tan B. Moo G.J., Liu S., Pumera M., Ohl CD. Graphene nanobubbles formed by water splitting. Nano lett. 17: 2833-2838, 2017.
An H., Jin B. Prospects of Nanoparticle-DNA Binding and its Implications in Medical Biotechnology. Biotechnol. Adv. 30: 1721–1732, 2012.
An H., Jin B. Impact of fullerene particle interaction on biochemical activities in fermenting Zymomonas mobilis. Environ. Toxicol. Chem. 31：712-716, 2012.
An H., Jin B. DNA exposure to buckminsterfullerene (C60): toward DNA stability, reactivity, and replication. Environ. Sci. Technol. 45: 6608–6616, 2011.
An H.*, Liu Q., Ji Q., Jin B. DNA binding and aggregation by carbon nanoparticles. Biochem. Biophys. Res. Commun. 2010, 393: 571-576
Yang W., Shen C., Ji Q., An H., Wang J., Liu Q., Zhang Z. Food storage material silver nanoparticles interfere with DNA replication fidelity and bind with DNA. Nanotechnology, 2009, 20: 085102
Zhang Z., Wang M., An H. Aqueous suspension of carbon nanopowder enhances the efficiency of polymerase chain reaction. Nanotechnology, 2007, 18: 355706.
Li H., Huang J., Lv J., An H., Zhang X., Zhang Z., Fan C., and Hu J.. Nanoparticle PCR: Nanogold-Assisted PCR with Enhanced specificity. Angew. Chem. Int. Ed. 2005, 44: 5100-5103
Single-molecule detection and Nanomanipulations
An H., Yang H., Liu Z., Zhang Z. Effects of heating modes and sources on nanostructure of gelatinized starch molecules using atomic force microscopy. LWT-Food Sci and Technol. 2009, 41: 1466-1471.
An H., Huang J., Lü M., Li M., and Hu J., Single-base-resolution and long-coverage sequencing based on single-molecule nanomanipulation. Nanotechnology, 18: 225101, 2007
An H., Guo Y., Zhang X., Zhang Y., Hu J. Nano-dissection of ss- and ds-DNA by atomic force microscopy. J. NanoSci. Nanotechnol. 5: 1656-1659, 2005
Lü J., Li H., An H., Wang G., Wang Y., Li M., Zhang Y., and Hu J., Positioning Isolation and Biochemical Analysis of Single DNA Molecules Based on Nanomanipulation and Single-Molecule PCR. J. Am. Chem. Soc. 126: 11136-11137. 2005
Yang H., An H. (Co-first author), Li Y. Manipulate and stretch single pectin molecules with modified molecular combing and fluid fixation techniques. Eur. Food Res. Technol. 2006, 223: 78-82
Yang H., Feng G., An H., Li Y. Microstructure changes of sodium carbonate-soluble pectin of peach by AFM during controlled atmosphere storage. Food Chem. 2006, 94: 179-192
Zhou X., Sun J., An H., Guo Y., Fang H., Su C., Hu J. Radial compression elasticity of single DNA molecules studied by vibrating scanning polarization force microscopy. Phys. Rev. E. 2005, 71: 062901(1-4)
Services
2021- present, Editorial member for Grain & Oil Science and Technology
2021- present, Review Editor for Diagnostic and Therapeutic Devices
2022 - present, Editorial member for Micromachines
Nano-Manipulations
Positioning nanomanipulation is a crucial cutting-edge technology for structural biology and personal care. It is in high demand to acquire specific single-molecule of biological samples of interest. Force spectroscopy senses the ultra-small force while an AFM tip unfolds a protein molecule. In addition, the isolation of single DNA/protein/lipid molecules is important for trace bioassay and personal genome analysis. This technique is motivated for an ordered DNA sequencing strategy by cutting and picking up a single DNA fragment from a batch genome DNA.
Single-molecule detection
An advanced vibrating scanning probe microscopy with picometer amplitude was developed to measure the nanomechanics of single-molecule polymer in liquids. It is also used to detect short-range forces, including hydrophilic or solvation forces, and the deformation of soft materials.
DNA-nanoparticle interactions
The widespread use of nanoparticles raises environmental risks, e.g. the potential impacts of the nanoparticles via DNA binding on the toxicity of the microorganisms. The nanoparticle–DNA binding could alter DNA molecular structure and its biochemical activities, and vary DNA detection, and gene therapy. We have done a few case studies, carbon/silver/gold nanoparticles, associated with the application of nanoparticle–DNA binding devices in medical detection and biotechnology. The information can provide useful references for further studies on biomedical science and technology.
Nanoparticle cytotoxicity and genotoxicity
The growing use of nanoparticles and associated products has raised a risk issue of the environment and human health. Previous research showed that evaluation of cytotoxicity and genotoxicity of nanoparticles can be difficult due to their structure, size distribution, shape and agglomeration state, surface chemistry and purity. Our research has recognized that the nanoparticles can penetrate the cell membrane, resulting in damaging the cells and altering their enzymatic, metabolic and genomic activities. Cellular uptake mechanisms can be driven by the types of cells, and size or surface chemistry of the nanoparticles.
Food function molecules
The texture is the principal quality attribute of fruits and foods that influences shelf life, transport capability and disease resistance of fruits, and ultimately affects acceptability by consumers. Structural changes that occur in the middle lamella and primary cell wall during ripening result in cell separation and softening of the tissue. The softening process is due to the solubilisation and depolymerisation of pectin and hemicellulose, and the correlation with texture during ripening has been found in a dozen fruits and vegetables. We investigated the individual structure of fruit and vegetable molecules, in particular, the microstructures during food processing and fruit storage, which is useful and important for the spatial arrangement of food functional molecules.
Starch chemistry
Starch is the main source of polysaccharides in plants and food, mainly composed of amylopectin and amylose. The content of each amylopectin and amylose in grains influences significantly the sense of touch and taste of food, e.g., sticky rice and long-shaped rice. The nature of starch chemistry such as enzyme degradation and starch-iodine interaction is extremely complex and remains a longstanding challenge, though there is great promise in applications for qualitative and quantitative analysis. Starch chemistry has been widely used in determining apple fruit maturity and then the first acceptable harvest date of fruits, in the evaluation of gene engineering and plant development, in curing female disease and iodine deficiency disorders, and in nanotechnologies.
Lipid bilayer
Membrane raft microdomains are postulated to be biologically important because of their physical and chemical properties. Sphingolipids and cholesterol preferentially pack into laterally organized regions in which proteins can be selectively included or excluded and play an important role in physiological functions such as maintaining membrane thickness and fluidity, limiting ion leakage, ensuring signal transduction, trafficking membrane proteins, mediating certain neurodegenerative disorders, and causing infertility. Cholesterol has also been shown to play a key role in mechanotransduction processes in endothelial cells and differential activation of extracellular signal-regulated kinase due to shear stress or hydrostatic pressure. We made lipid raft domains and investigated the role of cholesterol in these small, heterogeneous, highly dynamic domains that compartmentalize cellular processes.
Advanced microscopy
Ultra High Vacuum STM/AFM, Vibrating polarization FM, Vibrating DFM with picometer amplitudes, Darkfield microscopy, Total internal reflection fluorescence microscopy, and Reflection interference microscopy techniques were developed and are used for high-resolution imaging and nanomanipulations.
Identifying surface nanobubbles
Reproducibility and contamination are two main problems while generating surface nanobubbles. It is a long journey to prove or falsify that surface nanobubbles are gaseous. Once micro-pancakes are considered as gases with insufficient evidence. Our recent work uncovered this significant and long-standing problem by proving that the widespread use of one-use medical syringes in the field leads to the contamination of experiments in the field. We developed an AFM-only technique to unambiguously distinguish surface-attached nanobubbles from nanodroplets of oil by carefully controlling the orientation and magnitude of imaging forces, which fixed a long-standing inability in the field to distinguish gaseous bodies from liquid droplets. We also developed contamination-free techniques to produce surface nanobubbles by deposition of cold water on a warmer substrate.