Guide for Biodegradable Materials

Barret
Date: Jul 3,2020

There are many different types of biodegradable materials in the market. Few of them are processed naturally in the environment, such as Chitin. Other degradable materials are synthesized chemically. Through special processes, we could obtain material that meed our requirement. The most used is polylactide series and polycaprolactone.

In this post, we will explain all the details about biodegradable materials.

What Does Biodegradable Material Mean?

According to the Merriam Webster Dictionary, biodegradable means, “capable of being broken down especially into innocuous products by the actions of living things （such as microorganism）.” In 3D printing, this means that the material can break down over time. Using these materials is more environmentally friendly because it reduces carbon emissions and more.

Plastics take many years to degrade, and these biodegradable alternatives are important for the future of the planet. In fact, many governments are taking steps to ban single use plastics. As a result, there is a rise in the development of biodegradable materials used in different ways in three-dimensional printing.

What Makes a Material Biodegradable?

Biodegradable materials are simply materials that will break down quickly into harmless compounds with the action of microorganisms. For example, when you see a leaf fall off a tree, it degrades until there is nothing visible left. Fungi and bacteria break it down into smaller parts, and finally, it is broken down into elements that helped to make it, such as carbon dioxide and oxygen.

Biodegradable materials are made from natural ingredients that can degrade. This is achieved by minimizing the amount of processing the material goes through. The material needs to be plant-based, animal-based, or mineral-based to biodegrade, and how quickly it can do so is determined by how much it has been altered from its original state.

Examples of Biodegradable Materials

1.PLLA (poly-l lactide)

Poly-L Lactide is a biodegradable polymer that is often used in medical devices and pharmaceutical applications. It can be used to fabricate resorbable medical devices that degrade over time in physiological conditions.

This material is one of the easiest and most affordable polymers to use for this application. For example, they can be used to make a coronary stent and for bone tissue engineering. PLLA is able to degrade into lactic acid and breaks down over six months to two years in the human body. This makes it a great material for medical implants, including screws, plates, pins, and rods.

2. PDLLA (poly-d l-lactic acid)

PDLLA is a polymer obtained from the DL lactide, and it has a different structure from polymers obtained using only the L-lactide or the D-lactide. It is considered to be amorphous because the polymer is composed randomly of the repeating L-lactide and D-lactide units. It is mainly applied as dental devices or coatings.

PDLLA does not show a melting point, and it can be used as the coating for a suture. It is known to degrade faster than other polymer blends.

3. PCL (polycaprolactone)

Polycaprolactone is a biodegradable polyester that has a low melting point of close to 60 degrees Celsius. Its glass transition temperature is -60 degrees Celsius, and it is resistant to water, oil, solvents, and more. It is degraded by hydrolysis, and it can be used as a biodegradable implant material for the human body. It is successfully used in facial implants and other applications. It can also be used in targeted drug delivery.

4. PLGA (poly lactic co glycolic acid)

PGLA is obtained by the ring-opening co-polymerization of glycolide and lactide as monomers. Lactide has three optical isomers, so the copolymer is glycolide and L-Lactide is abbreviated to PLGA. Its primary use is as an absorbed suture. PGLA, with its higher content of glycolide.

PLGA is rigid and less flexible, which makes it good for drug delivery, stents, sutures, and more. It is a biodegradable and absorbable polymer.

5. PGA (polyglycolide)

PGA is a polymer that is obtained by the ring-opening polymerization of glycolide as a monomer. It is a synthetic braided polymer, and it does a good job of resisting infections from contaminating bacteria. It also retains at least 50% of its tensile strength over 25 days, which makes it good for sutures of the subcutaneous tissue. It is a tough fiber forming polymer that has also been used in the food packaging industry.

6. PTMC (poly trimethylene carbonate)

PTMC are polymers that work well for soft tissue regeneration and drug delivery. It is studied widely because it has a slow degradation time, which extends its lifetime and ends up with fewer adverse reactions inside the body. As a suture, it shows good handling and tying characteristics. It is also ideal for sutures under the skin because it can maintain closure of the skin long enough to give it time to heal.

7. PPDO (poly-p dioxanone)

PPDO is a polymer that is biodegradable, and it is used for drug delivery and sutures. It is also used for absorbable medical devices, including sutures. It is sufficient to use as a suture, a stent, an adhesion barrier, or reinforcement for an adhesion barrier. It is obtained by the ring opening polymerization of p-dioxanone. It is a multifilament, and it also works in pediatric cardiovascular procedures and other tissues that are still growing.

What Is Biodegradable Material Usually Made of?

1. Suture

In the past, sutures were placed in the skin, and they needed to be removed. Biodegradable materials have made it possible to make different sutures that can be absorbed by the body. They hold their integrity long enough to allow the body to heal, and then, they will biodegrade. You can use PLGA and PGA for sutures in subcutaneous tissue. In addition, PTMC works well for sutures under the skin that hold tissue together. PPDO works for deep tissues as well, especially in children as it works with tissue that is still growing.

2.Stent

Stent is placed into the artery to keep it open. Several of these biodegradable materials are excellent choices for this process. You can use PLLA as a coronary stent. PLGA and PGS are good materials for stents and are known to be resistant to infection. Being able to use these biodegradable materials have opened up new doors in the medical field.

3.Bone

3D printed biodegradable bone implants are able to help heal fractures and breaks, as well as other items. They can help support broken bones as they heal. For example, PLLA is used to make screws, rods, pins, and more, which are critical to healing a broken or fractured PDLLA is also used for bone plates and screws.

PCL is useful for helping the tissue around the bone to heal.

4. 3D Printing

3D printing is the process where you make a three-dimensional object from a digital file. You can use all different materials to print the object, including those listed above. When the computer tells the printer what to create, the filament comes out in layers. The 3D object is made once all of the layers are finished.

The biodegradable materials above have led to breakthrough discoveries in the medical field because sutures, stents, and devices to help bone repair can all be made via 3D printing using the biodegradable materials above.