Polymers as Biomaterials and Biodegradation
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Which of the following factors does NOT affect the degradation time of bioabsorbable polymers?

  • Environmental temperature (correct)
  • Material properties
  • Implantation site
  • Manufacturing process

    • Bioabsorbable polymers can be toxic when degrading.

    True

    What are the two types of degradation mechanisms mentioned for bioabsorbable polymers?

    Hydrolytic and enzymatic degradation

    The degradation time of bioabsorbable polymers depends on the polymer's ______ and ______.

    <p>molecular weight, structure/morphology</p> Signup and view all the answers

    Match the degradation factor with its description:

    <p>Hydrophobic = Repels water, may slow down degradation Hydrophilic = Attracts water, may enhance degradation Enzymatic = Releases reaction products influenced by specific enzymes Molecular weight = Influences the chain length and degradation rate</p> Signup and view all the answers

    Which polymer degrades faster due to its hydrophilic nature?

    <p>PGA</p> Signup and view all the answers

    PLA degrades completely in 3 to 5 years.

    <p>True</p> Signup and view all the answers

    What is the degradation product of PLA?

    <p>lactic acid</p> Signup and view all the answers

    PGA is more _____ compared to PLA.

    <p>hydrophilic</p> Signup and view all the answers

    Match the following polymers with their properties:

    <p>PLA = Degrades in 3 to 5 years PGA = Degrades in 3 to 6 months PCL = Slower degradation compared to PLA PDLA = Derived from D-lactide</p> Signup and view all the answers

    What applications are mentioned for PLA?

    <p>Drug delivery</p> Signup and view all the answers

    Polyesters like PLLA and PDLA have a high degradation rate.

    <p>False</p> Signup and view all the answers

    What is one method that can be used to improve the properties of polyesters?

    <p>Copolymization</p> Signup and view all the answers

    What is a characteristic of PGA?

    <p>Hydrophilic and semi-crystalline</p> Signup and view all the answers

    PLLA exhibits a very fast degradation process.

    <p>False</p> Signup and view all the answers

    What acid does PLGA degrade into?

    <p>lactic acid and glycolic acid</p> Signup and view all the answers

    PLLA can leave _______ residue that can cause a late inflammatory response.

    <p>crystalline</p> Signup and view all the answers

    Which property of PLCL is highlighted in the content?

    <p>Good drug release properties</p> Signup and view all the answers

    Match each polymer with its key property:

    <p>PGA = Fast degradation PLLA = High-crystalline and hydrophobic PLGA = Biocompatibility PLCL = Flexible and tailorable properties</p> Signup and view all the answers

    The lactide monomer in PLGA can alter its hydrophobic properties.

    <p>True</p> Signup and view all the answers

    What type of orthopedic implants can be made using PLGA?

    <p>Screws, nails, pins</p> Signup and view all the answers

    What is the primary degradation mechanism for polyglycolide (PGA)?

    <p>Combines hydrolysis and enzymatic degradation</p> Signup and view all the answers

    Only low molecular weight products are produced through the degradative mechanisms of synthetic bioabsorbable polymers.

    <p>False</p> Signup and view all the answers

    What is glycolic acid used for after the degradation of PGA?

    <p>It is eliminated through metabolic pathways as carbon dioxide and water.</p> Signup and view all the answers

    PGA is used in developing the first totally synthetic, bioabsorbable __________.

    <p>sutures</p> Signup and view all the answers

    Match the following synthetic bioabsorbable polymers with their corresponding types:

    <p>PGA = Homopolymer PLA = Homopolymer PLGA = Copolymers PBS = Copolymers</p> Signup and view all the answers

    Which of the following is NOT a characteristic of polyglycolide (PGA)?

    <p>Low melting point</p> Signup and view all the answers

    Cofactors can only function inside the cells.

    <p>False</p> Signup and view all the answers

    What two products result from the degradation of synthetic bioabsorbable polymers?

    <p>Low molecular weight products and water soluble products.</p> Signup and view all the answers

    What is the most common type of degradation for synthetic bioabsorbable polymers?

    <p>Hydrolytic degradation</p> Signup and view all the answers

    Natural polymers are commonly used in load-bearing applications.

    <p>False</p> Signup and view all the answers

    What is a significant benefit of bioabsorbable materials compared to traditional metal implants?

    <p>Less pain and avoiding operations</p> Signup and view all the answers

    Bioabsorbable materials can cause microplastic contamination in the body.

    <p>False</p> Signup and view all the answers

    Name one common bioabsorbable polymer used in medical applications.

    <p>Polylactide (PLA)</p> Signup and view all the answers

    Name one of the two major mechanisms of biodegradation.

    <p>Hydrolytic or Enzymatic</p> Signup and view all the answers

    Natural polymers are known for being __________ and enabling cell adhesion.

    <p>biocompatible</p> Signup and view all the answers

    The process by which polymers are broken down in the body and subsequently metabolized is known as __________.

    <p>bioabsorption</p> Signup and view all the answers

    Match the following disadvantages to the respective type of polymers:

    <p>Natural Polymers = Limited mechanical stability Synthetic Polymers = More stable physical properties</p> Signup and view all the answers

    Which area is NOT commonly associated with the application of bioabsorbable polymers?

    <p>Cosmetic surgery</p> Signup and view all the answers

    Match the type of degradation with its characteristic:

    <p>Hydrolytic degradation = Breakdown involving water Enzymatic degradation = Breakdown mediated by enzymes Bioabsorbable materials = Materials metabolized within the body Biostable materials = Materials that remain intact in the body</p> Signup and view all the answers

    Batch-to-batch variation in natural polymers can complicate their medical applications.

    <p>True</p> Signup and view all the answers

    Which of the following is NOT an advantage of bioabsorbable materials?

    <p>Permanent metal implant</p> Signup and view all the answers

    What strategies are used to improve the properties of natural polymers?

    <p>Mechanical reinforcement</p> Signup and view all the answers

    Bioabsorbable materials can interfere with imaging procedures.

    <p>False</p> Signup and view all the answers

    What is the ultimate goal of both hydrolytic and enzymatic degradation?

    <p>To produce low-molecular weight products that are water-soluble and can be cleared by the body's natural processes.</p> Signup and view all the answers

    Study Notes

    Polymers as Biomaterials

    • Polymers are used as biomaterials due to their variety of compositions, properties, and forms (solid, elastic, hydrogel).
    • They are easily fabricated into complex shapes (sheets, fibers, powders, films).
    • Biodegradation and reasonable costs make them suitable.
    • Biostable polymers are more complex, have higher strength and thermal resistance, but also are more expensive.
    • Bioabsorbable polymers are a focus for this lecture as a specific material type.

    Biodegradation Mechanisms

    • Two main types of biodegradation are Hydrolytic and Enzymatic.
    • Both aim to produce relatively low-molecular-weight water-soluble products.
    • These products are cleared by the body's natural processes.

    Polymer Classification

    • Polymers can be classified according to their properties (biostable, bioabsorbable) or origin (natural, modified natural, synthetic).

    Hydrolytic Degradation

    • Hydrolysis is a chemical reaction where a compound is broken down by reacting with water.
    • Chain scission is facilitated by water molecules breaking bonds (e.g., O and/or N) within the macromolecule.
    • Hydrolysis leads to bulk erosion (material loss throughout) or surface erosion (loss layer by layer).
    • Degradation time depends on water penetration rate, material properties (hydrophobic/hydrophilic).
    • Autocatalytic degradation occurs when degradation products speed up the degradation process because they are acidic.

    Enzymatic Degradation

    • Enzymes are proteins found in tissues that have an affinity for specific chemical groups in polymers.
    • These enzymes catalyze chemical reactions like hydrolysis and oxidation.
    • Degradation occurs outside or inside cells.
    • Enzymes cut molecular chains into smaller pieces.
    • Enzymatic degradation can occur after or alongside hydrolysis.

    Common Synthetic Bioabsorbable Polymers

    • Polyesters are a common synthetic bioabsorbable class of polymers.
      • Polyglycolic acid (PGA), a homopolymer, is highly crystalline, degrades rapidly.
      • Polylactic acid (PLA), also a homopolymer, is highly crystalline, degrades slowly.
      • Polycaprolactone (PCL), a homopolymer, has slower degradation and is well-mixed with other polymers.
      • Poly(lactic-co-glycolic acid) (PLGA), a copolymer, is commonly studied due to its biocompatibility and processability
    • Other copolymers, including poly(lactic-co-caprolactone), are used for their tailored properties.

    Copolymers

    • Homopolymers may not have good properties for medical applications.
    • Copolymerization offers a way to adjust properties (mechanical, degradation, crystallinity).
    • Copolymers like PLGA and PLCL are often used for their tailored properties.

    Hydrogel Applications

    • Hydrogels are hydrophilic polymers that swell in the presence of water.
    • They find applications as drug carriers, wound dressings, contact lenses, and tissue engineering scaffolds.
    • Injectable hydrogels allow for localized delivery of materials for cartilage, bone, and spinal cord repair, and are used to grow cells in their desired locations for tissue regeneration.

    (Modified) Natural Bioabsorbable Polymers

    • Natural polymers such as collagen, gelatin, fibrin, elastin, hyaluronic acid (important polysaccharide), chitosan, alginate, silk fibroin are extracted, purified, and modified for biocompatibility and degradability.
    • They have good biocompatibility but often have less stability than synthetic polymers.
    • Significant challenges include stability, batch-to-batch variation, and difficulty in processing.

    Materials Selection

    • Material selection depends on the specific needs for strength, flexibility, and resorption rates.
    • Different materials (e.g. biodegradable, synthetic and mixed) are tailored to meet specific requirements in different applications.

    General Announcements

    • Presentations, lectures, and practical labs are required. Information regarding times and places can be found on the specific course modules.
    • A summary of previous material is provided to ensure comprehensive understanding from the beginning to the end of the course
    • Exam details for a particular course/unit.

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    Polymers as Biomaterials PDF

    Description

    Explore the properties of polymers as biomaterials, focusing on their classifications and biodegradation mechanisms. Understand the differences between biostable and bioabsorbable polymers. This quiz will cover essential concepts related to polymer application and degradation in medical contexts.

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