Oct 10, 2024 03:47 AM
(This post was last modified: Oct 10, 2024 04:10 AM by C C.)
https://www.eurekalert.org/news-releases/1060824
EXCERPT: . . . The accidental discovery overcame several engineering challenges to replicating spider threads. Silk fibroin solutions can slowly form a semi-solid hydrogel over a period of hours when exposed to organic solvents like ethanol or acetone, but the presence of dopamine, which is used in making the adhesives, allowed the solidification process to occur almost immediately. When the organic solvent wash was mixed in quickly, the silk solution rapidly created fibers with high tensile strength and stickiness. Dopamine and its polymers employ the same chemistry used by barnacles to form fibers that stick tenaciously to surfaces.
The next step was to spin the fibers in air. The researchers added dopamine to the silk fibroin solution, which appears to accelerate the transition from liquid to solid by pulling water away from the silk. When shot through a coaxial needle, a thin stream of the silk solution is surrounded by a layer of acetone which triggers the solidification. The acetone evaporates in mid-air, leaving a fiber attached to any object it contacted. The researchers enhanced the silk fibroin-dopamine solution with chitosan, a derivative of insect exoskeletons that gave the fibers up to 200 times greater tensile strength, and borate buffer, which increased their adhesiveness about 18-fold.
The diameter of the fibers could be varied between that of a human hair to about half a millimeter, depending on the bore of the needle.
The device can shoot fibers that can pick up objects over 80 times their own weight under various conditions. The researchers demonstrated this by picking up a cocoon, a steel bolt, a laboratory tube floating on water, a scalpel partially buried in sand, and a wood block from a distance of about 12 centimeters.
Lo Presti noted that “if you look at nature, you will find that spiders cannot shoot their web. They usually spin the silk out of their gland, physically contact a surface, and draw out the lines to construct their webs. We are demonstrating a way to shoot a fiber from a device, then adhere to and pick up an object from a distance. Rather than presenting this work as a bio-inspired material, it’s really a superhero-inspired material.”
Natural spider silk is still about 1000 times stronger than the man-made fibers in this study. But with a little added imagination and engineering, the innovation will continue to improve and pave the way for a variety of technological applications... (MORE - missing details, no ads)
EXCERPT: . . . The accidental discovery overcame several engineering challenges to replicating spider threads. Silk fibroin solutions can slowly form a semi-solid hydrogel over a period of hours when exposed to organic solvents like ethanol or acetone, but the presence of dopamine, which is used in making the adhesives, allowed the solidification process to occur almost immediately. When the organic solvent wash was mixed in quickly, the silk solution rapidly created fibers with high tensile strength and stickiness. Dopamine and its polymers employ the same chemistry used by barnacles to form fibers that stick tenaciously to surfaces.
The next step was to spin the fibers in air. The researchers added dopamine to the silk fibroin solution, which appears to accelerate the transition from liquid to solid by pulling water away from the silk. When shot through a coaxial needle, a thin stream of the silk solution is surrounded by a layer of acetone which triggers the solidification. The acetone evaporates in mid-air, leaving a fiber attached to any object it contacted. The researchers enhanced the silk fibroin-dopamine solution with chitosan, a derivative of insect exoskeletons that gave the fibers up to 200 times greater tensile strength, and borate buffer, which increased their adhesiveness about 18-fold.
The diameter of the fibers could be varied between that of a human hair to about half a millimeter, depending on the bore of the needle.
The device can shoot fibers that can pick up objects over 80 times their own weight under various conditions. The researchers demonstrated this by picking up a cocoon, a steel bolt, a laboratory tube floating on water, a scalpel partially buried in sand, and a wood block from a distance of about 12 centimeters.
Lo Presti noted that “if you look at nature, you will find that spiders cannot shoot their web. They usually spin the silk out of their gland, physically contact a surface, and draw out the lines to construct their webs. We are demonstrating a way to shoot a fiber from a device, then adhere to and pick up an object from a distance. Rather than presenting this work as a bio-inspired material, it’s really a superhero-inspired material.”
Natural spider silk is still about 1000 times stronger than the man-made fibers in this study. But with a little added imagination and engineering, the innovation will continue to improve and pave the way for a variety of technological applications... (MORE - missing details, no ads)