(Top) Principle of biodegradable adhesive made by mixing poly(ethylene glycol)-poly(lactic acid) diblock copolymer and tannic acid in water. Yellow coacervate is precipitated by way of hydrogen bonding between the block copolymer micelles and tannic acid, and reveals adhesion. After warmth remedy, hydrogen bonds are rearranged to additional enhance adhesion. (Bottom) Adhesion comparability. Compared to utilizing poly(ethylene glycol) polymer (d), it could help 10 instances extra weight when utilizing block copolymer (e) and 60 instances extra weight after warmth remedy (f). The indicated G’ values characterize the elastic modulus of the fabric. Credit: JACS Au (2022). DOI: 10.1021/jacsau.2c00241
Medical adhesives are supplies that may be utilized to numerous makes use of corresponding to wound therapeutic, hemostasis, vascular anastomosis, and tissue engineering, and they’re anticipated to contribute drastically to the event of minimally invasive surgical procedure and organ transplants. However, adhesives which have excessive adhesion and low toxicity whereas additionally being able to decomposing within the physique are uncommon.
Adhesives based mostly on pure proteins, corresponding to fibrin and collagen, have excessive biocompatibility however inadequate adhesive power. Synthetic polymer adhesives based mostly on urethane or acrylic have larger adhesion however don’t decompose nicely and should trigger an inflammatory response within the physique.
A joint analysis crew led by Professor Myungeun Seo and Professor Haeshin Lee from the KAIST Department of Chemistry has now developed a bio-friendly adhesive from biocompatible polymers utilizing tannic acid, the supply of astringency in wine.
The analysis crew centered on tannic acid, a pure polyphenolic product. Tannic acid is a polyphenol current in massive quantities in fruit peels, nuts, and cacao. It has a excessive affinity and coating skill on different substances, and we sense the astringent style in wine when tannic acid sticks to the floor of our tongue. When tannic acid is blended with hydrophilic polymers, they kind coacervates, or small droplets of jelly-like fluids that sink.
If the polymers used are biocompatible, the combination will be utilized as a medical adhesive with low toxicity. However, coacervates are essentially fluid-like and can’t stand up to massive forces, which limits their adhesive capabilities. Thus, whereas analysis to put it to use as an adhesive has been actively mentioned, a biodegradable materials exhibiting robust adhesion as a consequence of its excessive shear power has not but been developed.
(a) Overview of a hair transplantation technique utilizing a biodegradable adhesive (proper) in comparison with a standard hair transplantation technique (left) that transplants hair containing hair follicles. After making use of an adhesive to the tip of the hair, it’s fastened to the pores and skin by implanting it by way of a subcutaneous injection, and repeated remedy is feasible. (b) Initial animal check outcomes. One day after 15 hair transplantation, 12 strands of hair stay. If you pull the three strands of hair, you may see that the entire physique is pulled up, indicating that it’s firmly implanted into the pores and skin. All strands of hair utilized with out the brand new adhesive materials fell off, and within the case of adhesive with out warmth remedy, the effectivity was 1/7. Credit: JACS Au (2022). DOI: 10.1021/jacsau.2c00241
The analysis crew discovered a method to improve adhesion by mixing two biocompatible FDA-approved polymers, polyethylene glycol (PEG) and polylactic acid (PLA). While PEG (which is used broadly in eyedrops and cream) is hydrophilic, PLA (a widely known bioplastic derived from lactic acid) is insoluble in water.
The crew mixed the 2 right into a block copolymer, which fashioned hydrophilic PLA aggregates in water with PEG blocks surrounding them. A coacervate created by mixing the micelles and tannic acid behaved like a strong as a result of arduous PLA elements, and confirmed an elastic modulus improved by a thousand instances in comparison with PEG, enabling it to resist a lot larger power as an adhesive.
Furthermore, the analysis crew noticed that the fabric’s mechanical properties will be improved by over 100 instances by way of a heating and cooling course of that’s used to heat-treat metals. They additionally found that that is as a result of enforced interactions between micelle and tannic acid arrays.
The analysis crew used the truth that the fabric reveals minimal irritation to the pores and skin and decomposes nicely within the physique to display its attainable utility as an adhesive for hair transplantation by way of an animal experiment. Professor Haeshin Lee, who has pioneered varied utility fields together with medical adhesives, hemostatic brokers, and browning shampoo, centered on the adhesive capacities and low toxicity of polyphenols like tannic acid, and now appears to be like ahead to it enhancing the constraints of present hair transplant strategies, which nonetheless contain follicle switch and are troublesome to be repeated
The analysis was printed on-line on August 22 within the journal JACS Au underneath the title “Biodegradable Block Copolymer-Tannic Acid Glue.”
Acid could also be key ingredient for higher adhesive power, digital elements
More data:
Jongmin Park et al, Biodegradable Block Copolymer–Tannic Acid Glue, JACS Au (2022). DOI: 10.1021/jacsau.2c00241
Provided by
The Korea Advanced Institute of Science and Technology (KAIST)
Citation:
Team develops biocompatible adhesive relevant to hair transplants (2022, October 10)
retrieved 10 October 2022
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