AP Biology class blog for discussing current research in Biology

Tag: Hydrogel

Birds Can Teach Us More Than Just Flying

Birds are known for their mostly beautiful, sometimes annoying songs, as well as their super flight abilities, but now, those shouldn’t be the only things they are known for. Scientists have observed the method small birds use to make their nests, as a guide to constructing cellulose gels in a nontoxic way. Scientists use a freeze-thaw process to make the cellulose. This process is modeled after how swift birds (not named after Taylor Swift) spit on the twigs in their nests to hold them together, but also to help connections form between the twigs. Cellulose gel is just a hydrated version of cellulose. Cellulose is the most abundant organic compound on earth. It is a chain of glucose that is different from starches because the glucose is in its beta form. It forms long chains that can build cell walls. It is a major constituent of paper and cotton. Most organisms can not digest cellulose, but inside of us, it acts as soluble fiber that stimulates the digestive tract to secrete mucus to help move feces along.

Cellulose is also a very useful material when it comes to making hydrogels, something that is used in a variety of things in the medical field ranging from contact lenses to wound care. Unfortunately, the process of creating hydrogels is not only difficult but can also be toxic. Normally, you would have to break down the cellulose and then get it to make the crosslink or structure of interest. This process often required the use of toxic, unstable, and/or difficult-to-handle solvents. Knowing how swift birds make their nests, The researchers added a water-soluble cellulose called carboxymethyl cellulose (CMC) to an acid solution and dissolved the CMC. After that, they added powdered cellulose fiber to the solution and put it through four rounds of freezing and thawing. This process generated cellulose gel. Repeatedly freezing and thawing the solution causes the cellulose to compact and intertwine itself into the sticky network. The researchers also did those processes with bamboo fibers and it was a success. This implies that this bird-like freeze-thaw process could be useful with other lignin and cellulose-containing fibers. The cellulose gels are robust, stable at room temperature, and can be tuned to degrade on a schedule, meaning that they’d be very helpful with drug delivery.

Do you think there’s anything else in nature that might hold the key to solving human challenges?

What are some other examples of humans learning from nature?

Little swift, Apus affinis, at Kruger National Park, South Africa, crop

Biomaterial Breakthrough: A New Hope for Heart Attack Patients

In the world of science and medicine, new breakthroughs are always being made. In very recent news, a team of researchers from the University of California San Diego has created a game-changing biomaterial that could be the answer to treating tissue damage caused by heart attacks. This new discovery is not only exciting for those suffering from heart conditions, but it also showcases the importance of understanding cell and tissue repair in AP Biology.

Here’s how it works: the biomaterial, which can be injected intravenously or infused into a coronary artery in the heart, is made from a hydrogel derived from the extracellular matrix (ECM) of cardiac muscle tissue. The hydrogel forms a scaffold in damaged areas of the heart, promoting cell growth and repair. In previous studies, the team had already proven the effectiveness of the hydrogel when injected directly into the heart muscle. However, this method could only be used a week or more after a heart attack, as injecting sooner could cause damage during the procedure.

But this new biomaterial takes things to the next level. It’s put through a centrifuge to sift out larger particles, leaving only nano-sized particles, and then undergoes dialysis and sterile filtering before being freeze-dried. Adding sterile water to the final powder results in a material that can be infused into a blood vessel in the heart or injected intravenously, allowing for immediate treatment after a heart attack.Depiction of a person suffering from a heart attack (Myocardial Infarction)

And that’s not all! The biomaterial was tested on rodent and porcine models of heart attacks, and researchers found that not only did it pass through blood vessels and into the tissue, but it also bound to cells and closed gaps in the blood vessels, reducing inflammation and accelerating healing. In addition, the team tested the hypothesis that the same biomaterial could help target inflammation in rat models of traumatic brain injury and pulmonary arterial hypertension.

So, why is this important from an AP Biology perspective? Well, in the course, we’ve learned about the body’s ability to repair and regenerate cells and tissues. By mimicking the B blood cells’ ability to reduce inflammation and react to an infection, this new biomaterial is a prime example of how that knowledge can be applied in the real world to help improve human health. It’s a new approach to regenerative engineering, and the possibilities of treating other difficult-to-access organs and tissues are endless.


The researchers, along with Ventrix Bio, Inc., a startup co-founded by lead researcher Karen Christman, are hoping to receive FDA authorization to conduct a study in humans within the next one to two years. This is exciting news for those affected by heart conditions, and we can’t wait to see what the future holds for this groundbreaking biomaterial.

Self-Assembling Hydrophobic Sandwiches

You read that correctly! Researchers at Rice University in Houston, Texas alongside Jeffrey Hartgerink have made a significant advance in injury treatment, illness education, and drug candidate by testing the self-assembling abilities of 3D printed nanofibrous multidomain peptide hydrogels, referred to as “hydrophobic sandwiches.” 


The main goal of Hartgerink’s team was to create a structure that could house cells and help them grow tissue by 3D printing the peptide ink. The printing allows researchers to recreate the complexity of biological structures due to their soft and flexible tissue-like feel, making this a major scientifical discovery and advantage. Hartgerink and his team describe their printed peptides as “hydrophobic sandwiches” due to their design, flexibility, and behavior. The peptides were printed to have one hydrophobic side and one hydrophilic side, allowing them to flip on top of each other when placed in water and resemble sandwiches. Like we learned in AP Biology, the hydrophillic qualities of one side will attract water, and the hydrophobic qualities of the other will repel water. Hydrophobic molecules repel water because they are nonpolar molecules, so they are not attracted to water, which is polar. Once the “sandwiches” were stacked after flipping in the water, they formed the hydrogels which can be vital to tissue engineering and wastewater treatments. 

Hydrogel Structure

The multidomain peptides have already been utilized due to their self-assembling nature for regenerating nerves, treating cancer, healing wounds, and encouraging tissue development throughout the body. Rather than only focusing on this aspect of the peptides, Adam Farsheed, a lead author in Hartgerink’s study, wanted to specifically highlight the fact that these peptides are an ideal 3D-printing ink choice due to their self-assembling nature. When testing the “sandwiches,” Farsheed took a unique, brute-force approach to add more of the material, rather than chemically modifying it, to test its function and ability to reassemble itself after deformation. He proved that adding more peptide material lets the peptide reassemble and heal itself extremely well after being deformed. This discovery will make the hydrogels an ideal candidate for scientific and medical usage.  

Through continued testing, he was also able to confirm that the peptides behave differently depending on their charge. The peptide cells with a negative charge tended to ball up on the substrate of the experiment and the positively charged cells spread out and started to mature on their own. Farsheed has confidently stated that their findings will allow the group to “control cell behavior using both structural and chemical complexity.” Both Hartgerink and Farsheed have made incredible contributions to the world of science through their studies using 3D-printed peptide hydrogels. 


Want To Replicate Cells?

If you are similar to me in that you aren’t satisfied with the current state of artificial cells and want to “more accurately replicate the gel-like properties of intracellular and extracellular biological environments” you’re in luck. New studies have been published that show how to do this, but first, we must understand what hydrogel is. Hydrogel is made of two polysaccharides: cellulose and chondroitin sulfate. A polysaccharide is a carbohydrate, meaning its elements are CH2O. Carbohydrates are found in sugars and starches, and they’re used for energy. Hydrogel is made by joining cellulose and chondroitin sulfate through a dehydration reaction. Forming a glycosidic linkage.


Now that we know hydrogel, how do you think it could be used to create artificial cells? The answer is in its backbone. Scientists graft anti-Hist-tag aptamers into the backbone of a bunch of polymers made up of cellulose and chondroitin sulfate, along with feeding nutrients this artificial cell can perform protein expression for more than 16 days. This discovery is used to accurately replicate intracellular and extracellular biological environments.

Here are some examples of how scientists plan to use these artificial cells: therapeutic delivery, biosensing, cell therapy, and bioremediation. Therapeutic delivery is the act of bringing a compound to a specific site in the body. Biosensing detects pathogens, such as E. coli, in food. Cell therapy is the act of injecting healthy cells into a patient. Lastly, bioremediation is when an organism consumes and breaks down pollutants in our environment. It’s astonishing to see every way these artificial cells can be used, and I hope you’re excited about how much these cells can help save lives.








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