A New Method to create microscale superstructures, HKU chemists develop shape-shifting agents for targeted load delivery in small quantities. In nature, structures that combine both soft and hard materials are often found. These structures are responsible for the various properties and functions of biological systems. As a common example, the human spine has a replacement of hard bones and a soft intervertebral disc, which is an important structure that supports the human body and maintains th
e flexibility.
The simulation of hard and soft natural processes can, in principle, inspire the design of mechanical devices and devices, such as human beings and robots. However, the implementation is very difficult, especially at the microscale, where the installation and processing of the material becomes insignificant.
With the goal of developing biomimetic materials on a scale that is visible, the research team of Dr. Yufeng WANG from the Department of Chemistry at the University of Hong Kong (HKU) has developed a new method to create a high-quality microscale material, called MicroSpine, which has both soft and hard materials that mimic the structure of the spine and can function as microactuators with flexible shapes. This progress, published in the scientific journal Science Advances, was made by colloidal assembly, a simple system of nanoparticles and microparticles that organize themselves simultaneously in the cosmic system.
Most living things, from mammals to arthropods and microorganisms, have a combination of soft and hard tissues. These structures are in different lengths, from micrometers to centimeters, and account for the functional activity of the biological system. They have also inspired the creation of artificial devices, such as actuators and robots, that change shape, move or act based on external signals.
Although soft hard materials are easy to produce on a large scale (millimeters and above), they are more difficult to achieve on a microscale (micrometers and below). In fact, it is increasingly difficult to integrate and manage different resources in a small way. Traditional manufacturing methods, such as lithography, face many limitations when trying to create small parts using top-down designs.
For example, low yields can occur because the production process is a little more complex and requires a lot of precision, which can increase the chance of defects and errors in the final product.
To overcome the challenge, Dr. Wang and his colleagues took a different approach, called colloidal assembly. Colloids are particles about 1/100 the size of human hair and can be made from a variety of ingredients. When properly designed, particles can interact with each other, assembling at once into ordered structures.
As a surface method, colloidal assembly is useful for creating microscale structures because it allows controlling the composition of the desired materials from different building walls, with a high yield. However, the difficulty is how to direct these particles to be assembled in a structure that is hard and soft.
Using the backbone as a basis, the team created new materials based on metal-organic structures (MOFs), emerging materials that can be assembled in high directions and specifications. Also being solid particles, these MOF particles can bond with the soft water molecules to form linear chains. The hard and soft elements take other positions in the chain, imitating the structure of the spine, i.e. MicroSpine.
“We introduce a method in which the soft chain parts can expand and contract when the MicroSpine is heated or cooled, so that it can change its shape,” explained Ms. Dengping LYU, author first of the subject, and a PhD Researcher in the Department of Chemistry at HKU.
Using the MicroSpine system, the team also showed different types of motion when the soft parts of the chain were selected. In addition, a cable has been used for the insulation and release of the guest material, which is controlled only by temperature.
The understanding of these functions is important for the development of the system in the future, because it can lead to the creation of intelligent microrobots that can perform complex tasks in small quantities, such as drug delivery, area detection and discovery. other applications. These unstructured and well-structured materials can be used to create more efficient drug delivery systems or sensors that can detect molecules with high sensitivity and precision.
The research team believes that this technology represents an important step towards creating complex microscale devices and machines. As Dr. According to Wang, “If you think about modern bikes like cars, they are put together by tens of thousands of different parts. Our goal is to achieve the same level of complexity by using different colloidal components. By taking inspiration from nature, the research team hopes to create more biomimetic systems that can perform complex tasks at the microscale and beyond.
Source: The University of Hong Kong
