Biomedical Note

Single-cell photoacoustic microscopy for early cancer diagnosis and brain imaging

Imaging of malignant tumour at an early stage is a key to cancer treatment. The biophotonics laboratory at City University of Hong Kong (CityU) is developing a novel technology called single-cell photoacoustic microscopy, which aims at cancer diagnosis at the earliest possible stage.

By combining light excitation and sound detection in a single modality, photoacoustic imaging can provide high-resolution imaging in deep biological tissue. Oxygen metabolism provides energy for tissue function and plays a key role in cancer progression. By tracking individual red blood cells in living tissue and measuring their subtle colour change, single-cell photoacoustic microscopy can quantitatively image oxygen metabolism at an unprecedented single-cell resolution, which enables the detection of small tumours at an early stage.

This author and his colleagues also applied single-cell photoacoustic microscopy to image and destroy circulating tumour cells, the main cause of cancer metastasis. Integrating an imaging laser and a therapeutic laser, single-cell photoacoustic microscopy can identify circulating tumour cells and purge them in the bloodstream, helping diagnosis of metastasis and lower the risk of tumour growth at new anatomical sites.

Single-cell photoacoustic microscopy has also been adapted to brain imaging. Oxygen metabolism in the brain is closely associated with not only neuronal activities, but also many life-threatening brain disorders, such as ischemic stroke, Alzheimer's disease, seizure, neurodegeneration and brain tumours. In vivo imaging of cerebral oxygen delivery is of crucial importance for understanding pathogenic mechanisms and exploring new therapeutic strategies in translational medicine. The CityU team has developed an ultrafast multi-wavelength laser system which enables spectral imaging at a line rate of one million per second. When combined with the new laser system, single-cell photoacoustic microscopy can image cerebral oxygen delivery with high resolution, fast imaging speed and large field of view, offering a powerful tool for translational research of the brain.

This article is contributed by Dr Wang Lidai, assistant professor in the Department of Mechanical & Biomedical Engineering, City University of Hong Kong; with the coordination of the Biomedical Division

Science in Brief

New method promises easier nanoscale manufacturing
Scientists at the University of Chicago (UChicago) and Argonne National Laboratory in the US have discovered a new way to precisely pattern nanomaterials that could open a new path to the next generation of everyday electronic devices.

The foundation of modern computing, the transistor, is manufactured using photolithography, which carves a stencil out of a layer of organic polymer by laying down a patterned 'mask' and illuminating it with ultraviolet light. After the new material is deposited on top, the polymer stencil is lifted off to reveal the pattern. Several rounds of such patterning build a miniature transistor onto the material.

However, it was originally developed for silicon and scientists are now looking at nanomaterials that can have unique and useful properties. To overcome the difficulty of manufacturing devices out of such materials, they have developed a new technique called DOLFIN, which makes different nanomaterials directly into 'ink' in a process that bypasses the need to lay down a polymer stencil. The UChicago team carefully designed chemical coatings for individual particles. These coatings react with light; when light is shone through a patterned mask, it will transfer the pattern directly into the layer of nanoparticles below, wiring them into useful devices.

"We found the quality of the patterns was comparable to those made with state-of-the-art techniques," said lead researcher Wang Yuanyuan, postdoctoral researcher at UChicago. "It can be used with a wide range of materials, including semiconductors, metals, oxides or magnetic materials - all commonly used in electronics manufacturing."

Statistical model spots anomalies in massive amounts of data
Researchers from the University of Oxford in the UK have developed a new statistical method for monitoring networks to automatically detect 'strange behaviour' and ultimately prevent security breaches and cyber-attacks.

Data arising in cyber-security applications often have a network structure. A tool that monitors networks has access to massive amounts of data of which 'normal' behaviour can be observed. "Since data on intrusions is lacking" notes Patrick Rubin-Delanchy, Heilbronn Research Fellow in Statistics at Oxford, "Accurate statistical modelling of connectivity behaviour has important implications, particularly for network intrusion detection."

The researchers have developed a 'linear algebraic' approach to network anomaly detection, in which nodes are embedded in a finite dimensional latent space, where common statistical, signal-processing and machine-learning methodologies are then available.

In contrast with traditional cyber-security approaches like anti-virus software, the new methodology is not based on hand-engineered signatures, but rather machine learning in which programmes can access and use the data and learn for themselves. "Our anticipation is that this model will provide a more robust approach to cyber-security in the future," Rubin-Delanchy said.

Paving over cigarette litter
Researchers at RMIT University in Melbourne, Australia, has demonstrated that asphalt mixed with cigarette butts can handle heavy traffic and also reduce thermal conductivity.

Trillions of cigarette butts are produced every year worldwide, with most discarded into the environment. They take a long time to break down while their toxic chemical load is released into creeks, rivers and the ocean.

Dr Abbas Mohajerani, a senior lecturer in RMIT's School of Engineering, has found a solution whereby cigarette butts are encapsulated with bitumen and paraffin wax to lock in the chemicals and prevent any leaching from the asphalt concrete.

"Encapsulated cigarette butts developed in this research will be a new construction material which can be used in different applications and lightweight composite products," Dr Mohajerani said. "This research shows that you can create a new construction material while ridding the environment of a huge waste problem."

About 6 trillion cigarettes are produced every year, leading to more than 1.2 million tonnes of cigarette butt waste. These figures are expected to increase by more than 50% by 2025, mainly due to an increase in world population.

"Cigarette filters are designed to trap hundreds of toxic chemicals and the only ways to control these chemicals are either by effective encapsulation for the production of new lightweight aggregates or by the incorporation in fired clay bricks," said Dr Mohajerani, who is also known for his research in recycling cigarette butts in bricks.

President's Protégé Scheme

Budding engineers from diverse disciplines to be mentored
In line with the HKIE's commitment to nurture future leaders, President Ir Thomas K C Chan has selected nine young engineers to become part of the President's Protégé Scheme. Here the Protégés for Session 2017/2018 give brief introductions of themselves.

Anne BEH Hui En
Due to a blessed opportunity for a scholarship, I came to Hong Kong to pursue my bachelor's degree in mechanical engineering at The University of Hong Kong in 2012. Upon graduation, I joined WSP (Asia) Ltd as an assistant engineer under Scheme "A" training.

My two years in this multinational consulting firm has given me wide exposure to various E&M projects. In addition to deepening my technical knowledge, I was able to develop my social networking and soft skills by meeting various people in the industry, which led to me having the chance to be the master of ceremony or part of an organising committee on several occasions.

I am grateful and honoured to be selected as a Protégé this year. I would like to dedicate myself to promoting the importance of engineering in our world and to continue bringing the HKIE to an international platform.

Cindy TSANG Mei Wai
Upon graduation from the Hong Kong University of Science & Technology with a bachelor's degree in chemical and biomolecular engineering, I joined the Hong Kong & China Gas Co Ltd (Towngas) as a graduate trainee in August 2016.

The two-year training programme provided by Towngas is fruitful. Diverse workshops and trainings enriched my technical knowledge of cutting-edge technologies and broadened my horizons. Involvement in innovative projects and corporate events also provided room for creativity and polished my social skills.

It is my honour to be selected as one of the Protégés this year. I would like to take this precious opportunity to broaden my exposure, especially in renewable energy development; and contribute to the HKIE and society by working closely under the President's guidance.

Emily FUNG Kwok Yi
Trained under the dual degree programme in technology and management at the Hong Kong University of Science & Technology, I was fascinated by the synergy between the disciplines and how innovation facilitated the development of a society. In 2011 the Innovation & Technology Scholarship offered me an opportunity to be an intern at the Development Bureau and a mentee of the Permanent Secretary for Development (Works), which inspired me to contribute to society as an engineer.

Upon graduation, I joined Ove Arup & Partners Hong Kong Ltd, where I am currently working as an assistant engineer. Living up to the expectation I set for myself, I am excited to be one of the President's Protégés and will strive to promote synergy across all engineering disciplines, to shape a better world.

Kelsey CHOW Ming Wai
I graduated from The University of Hong Kong with a bachelor's degree in mechanical engineering and joined MTR Corporation Ltd (MTR) as a graduate engineer for two years of Scheme "A" training while continuing to study for a law degree under the University of London's international programme.

Being an MTR graduate engineer is exciting. I can be involved in mega projects such as the Express Rail Link and Shatin-Central Link. In addition, I am currently one of the team members for an overseas project MTR has in North America. I am very enthusiastic about the opportunity to gain overseas working experience.

It is my honour to be selected as one of the President's Protégés. I look forward to shadowing the President and working alongside my fellow Protégés in promoting the engineering profession to society.

Eric YAU Kai Pui
Upon graduation from The University of Hong Kong in 2016 with a bachelor's degree in medical engineering, I joined the Electrical & Mechanical Services Department (EMSD) as a biomedical engineering graduate.

The two-year training at the EMSD enriched me with lots of technical knowledge on medical engineering, which has helped me develop my engineering mindset and become a well-equipped engineer. Determined to help people in need through my profession, I engaged in social services with my EMSD colleagues. I also joined a volunteer group working on innovative designs to raise the living standards of the disabled and elderly. These experiences broadened my exposure and strengthened my knowledge.

It is my honour to be selected as one of the Protégés this year. I will devote myself to promoting the engineering profession and inspiring more talented youngsters to pursue a career in engineering.

Steven LEUNG Yu Kit
Upon graduation from The Hong Kong Polytechnic University (PolyU) in 2016 with a bachelor's degree in building services engineering, I joined Hip Hing Construction Co Ltd (Hip Hing) as an assistant construction officer.

Under the construction officer development programme, I am undergoing rotation to different sections of a construction project. This comprehensive graduate training programme has enriched my technical knowledge in multiple disciplines and equipped me to be a potential project manager in the future.

Before joining Hip Hing, I was active in two engineering-related societies in the PolyU, which provided me with chances to organise engineering-related events on campus and in the community. I also developed a subject registration referencing system called 'EasyReg' for the PolyU students, which recorded over 80,000 visits over the past two years and is still in service.

It is my honour to be selected as one of the HKIE President's Protégés. I am dedicated to promoting the engineering profession to the community and raising youngsters' interest in the engineering discipline.

Randall LEE Wing Hang
I graduated from the Hong Kong University of Science & Technology with a double bachelor's degrees in civil engineering and business. During my studies, I acquired not only technical knowledge but also international perspectives through a research programme at Princeton University and an exchange programme at the University of Illinois.

Upon graduation, I joined the Geotechnical Engineering Office of the Civil Engineering & Development Department as a geotechnical engineering graduate in 2016. Under the comprehensive and well-organised training scheme, I gained insight into geotechnical engineering in both theory and practice.

As a President's Protégé, I am devoted to sharing my passion for engineering and committed to serving the HKIE and society.

Jenny LIN Jia
Upon graduation from North China Electric Power University (Beijing) with a master's degree in electrical engineering, I joined CLP Power (Hong Kong) Ltd (CLP) as a graduate trainee in August 2016.

Owing to the well-organised training programme provided by CLP, I gained practical engineering knowledge in different teams under the guidance of experienced engineers and had opportunities to talk with pioneers in multiple domains. Both my engineering sense and soft skills were cultivated. Prior to graduation, I devoted time to research into compressed-air energy storage and renewable energy. Through field research in areas with abundant wind power resources such as Xinjiang and Liaoning Province in the Mainland, I tried to find out how renewable energy can be commercially utilised and its impact on the power grid managed.

Being selected as one of the Protégés this year, I have the honour to shadow the President and cooperate with my fellow Protégés closely. I aspire to mix engineering with art and culture in order to enrich public understanding of engineering.

Derek TANG Chung Hin
Upon graduation from the Hong Kong University of Science & Technology (HKUST) with a bachelor's degree in civil engineering, I joined Meinhardt C&S Ltd as a graduate geotechnical engineer.

During my training, I participated in the design of site formation works, a tunnel, and the excavation and lateral support for the Liantang/Heung Yuen Wai Boundary Control Point. This project is challenging; my team and I have to propose different measures to avoid any hazards caused by adverse geological conditions. This has enabled me to gain technical knowledge and hands-on experience in tackling geological problems.

Apart from work, my passion for civil engineering has driven me to join various activities to train up myself, such as membership of the executive committee of the HKUST Civil Engineering Students' Society and being a master of ceremony, etc.

It is my honour to be selected as one of the Protégés this year. I look forward to exchanging ideas with experts from different disciplines and working alongside my fellow Protégés in taking the engineering industry to a new horizon.

Anne BEH Hui En

Cindy TSANG Mei Wai

Emily FUNG Kwok Yi

Kelsey CHOW Ming Wai

Eric YAU Kai Pui

Steven LEUNG Yu Kit

Randall LEE Wing Hang

Jenny LIN Jia

Derek TANG Chung Hin

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