Deciphering the “catalytic black box”

Powerful catalysis

　　Human production and life are inseparable from chemistry, which is related to health, environment, energy and other fields. Many of the clothes we wear, the food we eat, and all kinds of daily necessities are provided by the chemical industry. Achieving control over chemical reactions is the key to chemical scientific research. To make chemical reactions more precise and controllable, catalytic technology is needed to help.
　　Catalysis is a phenomenon that accelerates or slows down the rate of chemical reactions due to the intervention of catalysts, and is a common phenomenon in nature. Catalysis is so powerful that it pervades almost the entire field of chemical reactions. To really understand it, we must first understand a term for chemical reactions – energy barrier.
　　The existence of energy barriers is very necessary. We can imagine that if there is no energy barrier, any two substances can have a chemical reaction when they meet, then our life will really be a “big bang”!
　　But the energy barrier is too high and the chemical reaction cannot proceed, or the reaction is extremely slow. What should I do if the energy barrier is too high? This is the time for the catalyst to “make a big splash”.
Catalysts can also run into trouble

　　Catalysis is achieved through catalysts. The larger the surface area of ​​the catalyst, the more active sites on the surface, and the higher the catalytic activity of the catalyst. Just like when we cook meat, we cut it into small pieces instead of putting the whole piece into the pot. In fact, it is to increase the contact area between the meat and the sauce, so that the taste of the sauce can soak into the tissue of the meat from more contact surfaces, making the meat more fragrant.
　　However, in the process of use, the catalyst is often lost, and even agglomerates, resulting in a serious reduction of the surface area. This problem was successfully solved by the emergence of “nano-confined catalysis”.
“Constraining” catalysts with scientific means

　　How to understand “limited area”? In simple terms, confinement is to provide a constrained environment for catalytic reactions. Scientists have discovered the phenomenon of narrow confinement catalysis in carbon nanotubes. The cavities of carbon nanotubes are extremely small, about one-60,000th the diameter of our hair. Confining the catalyst in the carbon nanotubes can prevent the catalyst from agglomerating and ensure the activity of the catalyst. Moreover, in this extremely small space, the catalyst can also show unique catalytic properties.
　　Through “nano-confined catalysis”, scientists can control the reaction interface, atmosphere and environment to constrain and stabilize the active state of catalysis.
　　Today, the new concept of “nano-confined catalysis” has been generally verified in the international academic community. It is believed that in the future, it will promote the development of catalysis and shine in more fields.

　　Scientists propose that in the future, humans can store their own stem cells in advance, and when they need new neurons, muscle cells, and skin cells, they can be extracted from this “stem cell bank”, and the body’s immune system will not reject them. or attack these new cells. In fact, your body doesn’t even realize that these new cells are being made in a cell factory. Breakthroughs in recent years at the intersection of biology, laser physics and machine learning have made this vision possible.
　　How is this achieved? First, let’s start with physics.
Introduction to Stem Cell Therapy

　　The human body is a miracle of nature. Hundreds of millions of cells work synchronously to pump blood and secrete dopamine for us, allowing us to experience the world. But as we age, our cells get older, the skin starts to loosen, the cartilage in the body starts to wear down badly, and so on. Aging and disease are natural laws, but stem cells can delay this law because stem cells can become totipotent replacement cells.
　　Stem cells, a kind of primitive cells with self-renewal ability and multi-directional differentiation potential, are the origin cells of the body. Under certain conditions, they can differentiate into various functional cells or tissues and organs, so they are also called “universal cells”. After stem cells are implanted into the human body, they can replace damaged cells for repair, so as to achieve the purpose of treatment. This is stem cell therapy (Stem-celltherapy).

Schematic diagram of stem cells

stem cell therapy

　　By isolating, culturing, and directional inducing differentiation of stem cells in vitro, new, normal and younger cells, tissues, organs, etc. can be cultured. It is then transplanted into the body through special transplantation technology to replace those sick or abnormal cells, thereby restoring the body’s function. In fact, stem cell therapy is not new. There are numerous cases of hematopoietic stem cell transplantation to cure leukemia. This technology can also be applied to the treatment of diseases such as liver cirrhosis and cerebral palsy.
Stem cell therapy encounters difficulties

Manual assessment of stem cells

Scientists project through microscopes, manually assess and remove unwanted cells

Custom stem cells aim to make medicines that actually work for everyone

　　Stem cell therapy is an important research and application direction of future medicine. However, making stem cells is not an easy task, requiring the extraction of blood cells from patients and adding chemicals to turn them into stem cells. However, what you end up with in real life is a very messy plate of cells with different orientations (towards the eye, the brain, the liver), and these random cells have to be removed.
　　Previously, researchers had to manually remove these random cells. During Nabiha’s first visit to the Harvard Stem Cell Institute, he saw a scientist observing and evaluating stem cells—using their years of experience and expertise to identify which cells were of poor quality and remove unwanted cells. This manual process is time-consuming, tedious, and yields little. The cells that can eventually pass the final quality assurance test required for human transplantation account for about 10% to 20% of the total, so customized stem cell banks are valuable.
　　To make the stem cell production process scalable and affordable, the process needs to be automated, and Dr. Nabiha decided to use physical methods to overcome this challenge.

Process map of stem cell laser customization technology
Stem cells meet laser

　　Nabiha proposed during his studies that lasers could be used creatively to design and modify cells. Before graduating, she patented the invention of cell laser editing — which can target any one of millions of cells at precise time intervals.
　　To improve the automation of the process of removing unwanted cells with a laser, Nabiha formed a team after graduation, attracting a large number of researchers with backgrounds in physics, stem cell biology and machine learning to collaborate. They used machines to learn to identify unwanted cells and remove them, and they developed algorithms that were also effective at finding useful information and images, and became a perfect use case for machine learning, revolutionizing the regenerative medicine industry.
　　The principle of the stem cell laser customization technology is: take some blood cells, put them in a cartridge, add chemicals to the blood cells to make them stem cells, and the machine recognizes the unwanted cells and kills them with a laser.
　　In order to determine the level of cell quality, researchers also collected a large amount of data and applied algorithms to determine cell quality based on various factors. Cell quality is judged by cell morphology—that is, the shape, size, and density of cells.
　　The machine decides when and how often to print the cells and uses a fully automated system to run the entire process. After repeated pruning, an exclusive, perfect stem cell culture is obtained, ready to be deposited in the Stem Cell Bank and used.
What is the future of stem cell therapy

　　As costs come down, scientists can conduct larger and larger clinical trials to develop treatments that don’t yet exist. And it can bring different ideas to the development of new drugs, which may make the future more interesting.

In the future, there will be large-scale stem cell farms with millions of cassettes holding everyone’s customized stem cell bank

　　For example, the way we take medicine right now is kind of a trial and error, you don’t know for sure if the medicine is going to work for you, you just put it in your body first. But what if we had a chip that contained tiny human replicas of your cells (like eye cells, brain cells, heart cells, muscle cells, blood cells). We can test them first in the lab to see if they work. If it works, you can take the medicine; if it doesn’t, the pharmacist can customize the medicine for you. This is also the hope and dream of scientists for many years.
　　If the 20th century was the era of drug therapy, then the 21st century is the era of customized cell therapy. One day, we will be able to find a treatment method suitable for every patient. With the rapid development of science and technology, I believe this day will come much faster than you think.