The Chemistry of Dissolvable Sutures

Introduction

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  • Sutures, commonly known as stitches, play a key role in the body’s recovery process with lacerations of the skin. The sutures bind the skin together and help the body tissue heal faster than it would without sutures. Overall there is a wide variety of different sutures, but they are mainly categorized into two groups, the kind that dissolve and the kind that do not. Within those two groups there is one main factor, if they are they made from synthetic or natural materials.

  • I chose to do to the chemistry of dissolvable sutures because I have personally had them in the past, and I work at a place that uses them almost everyday.

  • Dissolvable sutures have affected my life by helping my leg recover from surgery when I broke my femur. After the surgery  the dissolvable sutures that were under my skin kept my body tissue together, with the help of staples on top of my skin. Eventually I had to get the staples removed but the dissolvable sutures that were under my skin stayed, that is until my body naturally broke them down.

Composition of ...

Natural sutures

  • Catgut

    • sheep or cattle intestines

    • collagen (abundant protein that holds body together)

  • Cotton (C6H10O5)n

  • Silk

  • Linen

Synthetic sutures

  • Polyglycolic acid (PGA) or aka Polyglycolide (C2H2O2 )n

  • Polylactic acid(C3H4O2)n

  • Polydioxanone (biodegradable synthetic polymer and has a colorless crystalline structure) C4H6O3

  • Poliglecaprone (PGLA) C10H14O6

  • Polyglactin 910 (aka Vicryl) C10H12O8

Coatings

  • Poloxamer 188 C5H10O2

  • Calcium stearate with glycolide-lactide copolymer (lactic and glycolic acid)

    • Lactic acid CH3CH(OH)CO2H

    • Glycolic acid C2H4O3


Main Chemicals, Compounds, Components

Catgut is the main component in the natural type of dissolvable sutures. It comes from the dried, twisted intestines of animals, mainly from sheep intestines. The part of the intestines that is used is the collagen which is an abundant protein in the body that is found in places like our bones,tendons, muscles and skin. It is important because it holds our bodies together as well as gives us structure. In the making of the catgut sutures the collagen is cut and cleaned. Once the catgut is purified they twist the strips together to insure a tough single strand. Lastly they sterilize the catgut strand with a sterilizing solution that is a combination of distilled water, isopropyl alcohol and ethylene oxide.

Polyglycolic acid (PGA) or polyglycolide  is one of many types of plastic that make up synthetic sutures. This plastic differed from the other because, up until 1962 it did not have many uses, that was until it was used to make one of the first synthetic sutures. It’s chemical formula is (C2H2O2 )n. It is a biodegradable polymer that has a high melting point but does not have a boiling point. There are many different ways polyglycolic acid can be obtained and depending on which method you use to make polyglycolic acid the products molecular weight could vary.


Chemistry's Role

Chemistry plays a major role in the breakdown of dissolvable sutures. Natural and manmade sutures will appear as a foreign substance to the body and that is why the body attacks the sutures, therefore dissolving them. Depending on which type of sutures are being used, natural or man made the chemistry behind it differs. If natural sutures like catgut are being used in the body then it will be dissolved or absorbed by enzymatic degradation. Enzymatic degradation is a process where proteolytic enzymes that are usually found in the digestive tract dissolve the natural suture.These enzymes can also be referred to as peptidase, proteinase, or protease. The enzyme is separated into two different groups endopeptidase, and exopeptidase. The endopeptidase will break down the inside of the protein while the exopeptidase breaks down the outer ends of the protein. They work together to break the protein down into an amino acid.

Synthetic sutures such as polyglycolic acid are broken down in the body by a process called hydrolysis. Hydrolysis means “to split by water”, it got its name because of how water and enzymatic catalyst work together to break down the sutures. In the process of hydrolysis the body breaks polymers down to monomers. Basically the opposite of dehydration, where monomers turn into polymers and form water. The polymer is broken into two parts, then there is the factor of whether or not the polymers can be ionized or broken down into ions. If the polymer can be ionized then one part will gain an oxygen as well as a negative charge, while the other part will gain two hydrogen(H+) atoms and a positive charge. On the other hand if the polymer cannot be broken down into ions then one part gains a hydrogen(H+) atom and the other will gain a hydroxide(OH-) ion.


Background Research

Sutures have been used for thousands of years, it has been discovered that even ancient Egyptians used them for medical purposes. Dissolvable sutures are used for inside the body, whereas non dissolvable sutures are used on the outside of the body and are eventually removed. Sutures have different thicknesses,elasticity and decomposition rates, which help the sutures adjust to different kinds of lacerations. Sutures range in sizes from 11-0 to 7 and are usually attached to a curved needle.There are braided sutures, and chromic sutures which are single stranded.  When in the body  the dissolvable sutures must be taken care of, they will itch but itching them may ruin them, and by staying away from dirt, mud or anything that could get in the wound and infect it. Signs to look for when checking if the wound with sutures is infected would include bleeding, swelling,or pus coming from the wound itself. Other signs would be a bad odor or a red appearance coming from around the wound, and an increase of pain from the area. It is important to check in with your doctor if any of these symptoms occur.

Resources

http://science.howstuffworks.com/innovation/everyday-innovations/question611.htm

  • What are dissolvable sutures made of

  • Features of sutures

  • Difference in sutures

  • why the body breaks them down

https://en.wikipedia.org/wiki/Surgical_suture#Materials

  • synthetic material

  • needle types and techniques used to sew sutures

  • Hydrolysis and proteolytic enzymatic degradation- 2 ways chemistry is involved

http://www.surgisolution.com/blog/difference-between-absorbable-and-non-absorbable-surgical-sutures/

  • types of sutures and where they are used on the body

http://www.madehow.com/Volume-7/Suture.html

  • raw materials in sutures (absorbable and nonabsorbable)

  • different designs of sutures

  • manufacturing the thread

  • history of sutures (how far back they have been used)

http://www.upstate.edu/surgery/pdf/education/clerkship/suture_types.pdf

  • synthetic and natural suture material

  • types of natural and synthetic sutures

  • size and where they are used on body

  • other surgical instruments and descriptions

http://www.just-health.net/Dissolvable-Stitches.html

  • how dissolvable stitches work

  • how to take care of sutures

  • what happened when they get infected

http://www.medicalnewstoday.com/articles/262881.php

  • collagen what it is and does, where in the body

http://www.ethicon.com/healthcare-professionals/products/wound-closure/absorbable-sutures/surgical-gut-suture

  • gut sutures composition and sizes

  • description of sutures

https://en.wikipedia.org/wiki/PLGA

  • glycolide-lactide copolymer composition (lactic acid and glycolic acid )

https://en.wikipedia.org/wiki/Polydioxanone

  • what polydioxanone is and how it is used

https://en.wikipedia.org/wiki/Lactic_acid

  • lactic acid formula,characteristics and uses

https://en.wikipedia.org/wiki/Glycolic_acid

  • glycolic acid  formula, uses and properties

http://healthcert.com.au/product-of-the-month/catgut_sutures-_a_timeless_classic_or_a_thing_of_the_past

  • what catgut is and other uses for it

  • enzymatic degeneration by body for catgut

  • how it's made into sutures

  • hydrolysis by body for synthetic

https://en.wikipedia.org/wiki/Polyglycolide

  • degeneration process of polyglycolide

  • uses and properties of polyglycolide

  • helped develop first dissolvable sutures

https://en.wikipedia.org/wiki/Catgut_suture

  • how catgut is manufactured

  • some background information

https://www.boundless.com/biology/textbooks/boundless-biology-textbook/biological-macromolecules-3/synthesis-of-biological-macromolecules-53/hydrolysis-295-11428/

  • hydrolysis “to split by water”

  • polymers to monomers

  • enzymatic catalyst

  • differences between dehydration and hydrolysis

  • ionized (turned into ions)

  • unionized (one gains hydrogen other gain hydroxide)

http://pubchem.ncbi.nlm.nih.gov/compound/71391

  • polyglactin 910 formula

http://pubchem.ncbi.nlm.nih.gov/compound/65431#section=Top

  • Poliglecaprone formula

http://pubchem.ncbi.nlm.nih.gov/compound/18233

  • polydioxanone formula

http://pubchem.ncbi.nlm.nih.gov/compound/Poloxamer_188

  • poloxamer 188 formula

http://www.britannica.com/science/proteolytic-enzyme

  • proteolytic enzyme information and how it degrades catgut sutures

https://en.wikipedia.org/wiki/Cellulose

  • cottons chemical formula

About the Author
April Zimmerman is a junior at Billings Senior High. She is a member of the Billings Senior High tennis team as well as the orchestra. She also has a part time job at a local veterinary clinic. In her free time she enjoys hanging out with friends, watching tv, and spending time with her dog.
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