Hydrogels in Medicine Quiz
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Questions and Answers

What type of interactions can cause crosslinks in hydrogels?

  • Single covalent bonds, double covalent bonds, triple covalent bonds, coordinate covalent bonds
  • Ionic bonding, metallic bonding, dipole-dipole interactions, London dispersion forces
  • Ionic bonding, covalent bonding, metallic bonding, van der Waals interactions
  • Covalent bonding, hydrogen bonds, van der Waals interactions, ionic interactions (correct)

    • What type of polymer yields a hydrogel when lightly crosslinked?

  • Highly crosslinked elastomer
  • Lightly crosslinked thermoset
  • Lightly crosslinked hydrophilic polymer (correct)
  • Highly crosslinked polymer

    • What forces can form non-covalent physical hydrogels?

  • Covalent bonding, hydrogen bonds, van der Waals interactions, ionic interactions
  • Molecular entanglements, van der Waals, hydrogen bonding, hydrophobic forces (correct)
  • Hydrogen bonding, metallic bonding, coordinate covalent bonds, London dispersion forces
  • Ionic bonding, metallic bonding, dipole-dipole interactions, London dispersion forces

    • What is the classification based on ionic charges for hydrogels?

    <p>Neutral, Anionic, Cationic or Ampholytic</p> Signup and view all the answers

    What type of hydrogel classification involves more than three types of mers?

    <p>Multipolymer hydrogels</p> Signup and view all the answers

    What is the term for the connections between chains in a hydrogel?

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

    What is the ideal network structure involving tetrafunctional covalent crosslinks called?

    <p>Ideal network with tetrafunctional covalent crosslinks</p> Signup and view all the answers

    What can be controlled by polymer composition and crosslink density in hydrogels?

    <p>Swelling Ratio</p> Signup and view all the answers

    What is the term for a polymer comprising two or more networks which are at least partially interlaced on a molecular scale but not covalently bonded to each other?

    <p>Interpenetrating Polymer Network (IPN)</p> Signup and view all the answers

    What is the purpose of blood-compatible coatings using hydrogels?

    <p>Preventing protein deposition and platelet adhesion</p> Signup and view all the answers

    What type of hydrogel is used for tissue engineering scaffolds such as artificial tendon and cartilage?

    <p>Hydrogels with controlled swelling ratio</p> Signup and view all the answers

    What is the term for a polymer network that absorbs water and expands after polymerization?

    <p>Swelling hydrogel</p> Signup and view all the answers

    What is the term for the ratio of the weight of swollen sample to that of the dry sample expressed as percentage?

    <p>Weight ratio</p> Signup and view all the answers

    What is the term for a mixture of two or more preformed polymer networks that is NOT an Interpenetrating Polymer Network (IPN)?

    <p>A mixture of two or more preformed polymer networks</p> Signup and view all the answers

    What type of interactions can cause crosslinks in hydrogels?

    <p>Chemical reaction</p> Signup and view all the answers

    Match the following with their description:

    <p>Hydrogels = Water swellable crosslinked polymers Thermoset = Highly crosslinked polymer Elastomer = Lightly crosslinked polymer JELL-O = Hydrogel made from a naturally derived polymer</p> Signup and view all the answers

    Match the following with their examples:

    <p>Covalently Crosslinked Hydrogels = pHEMA + EGDMA (Ethylene Glycol Dimethacrylate) Non-covalent Physical Hydrogels = Formed by molecular entanglements and/or secondary forces such as van der Waals, H-bonding or hydrophobic forces Polymers = Comprising two or more networks which are at least partially interlaced on a molecular scale but not covalently bonded to each other Crosslinks = Connections between chains in a hydrogel</p> Signup and view all the answers

    Match the following with their primary cause of crosslinks:

    <p>Covalently Crosslinked Hydrogels = Crosslinks caused by reaction (covalent bonding) between 'mers' Non-covalent Physical Hydrogels = Formed by molecular entanglements and/or secondary forces such as van der Waals, H-bonding or hydrophobic forces Ionic interactions = Cause of crosslinks in hydrogels van der Waals interactions = Cause of crosslinks in hydrogels</p> Signup and view all the answers

    Match the following hydrogel classification with their descriptions:

    <p>Homopolymer hydrogels = Hydrogels formed from one type of hydrophilic mer Copolymer hydrogels = Hydrogels formed from two types of mers, at least one hydrophilic Multipolymer hydrogels = Hydrogels formed from more than three types of mers Interpenetrating polymeric hydrogels = Hydrogels formed by swelling a network of polymer1 in mer2 or making intermeshing network of polymer1 and polymer2</p> Signup and view all the answers

    Match the following hydrogel classification with their structural or morphological properties:

    <p>Amorphous hydrogels = Hydrogels with a random network structure Semicrystalline hydrogels = Hydrogels with dense regions of 'order' Non-covalently bonded hydrogels = Hydrogels formed through assembly systems Crosslink structure = The ideal network structure with tetrafunctional covalent crosslinks (rare)</p> Signup and view all the answers

    Match the following hydrogel classification with their ionic charges:

    <p>Neutral hydrogels = Hydrogels with no net charge Anionic hydrogels = Hydrogels with a negative charge Cationic hydrogels = Hydrogels with a positive charge Ampholytic hydrogels = Hydrogels with both positive and negative charges</p> Signup and view all the answers

    Match the following components with their role in the design of hydrogels:

    <p>Hydrophilic component = Monomers, oligomers, or polymers bearing polar groups like hydroxyl (-OH), carboxyl (-COOH), amide (-CONH), sulfhydryl (-SH), sulfate (-SO3H) etc. Crosslinking component = Bifunctional or multifunctional mer used for crosslinking the hydrogel Radiation reactions = Inducing crosslinks in hydrogels through electron beams, gamma-rays, X-rays, or UV Chemical crosslinking = Creating crosslinks in hydrogels using small molecular weight crosslinking agents or copolymerization-crosslinking reactions</p> Signup and view all the answers

    Match the following forces with their role in the swelling of hydrogels:

    <p>Swelling force = The thermodynamically driven force that causes the polymer network to absorb water and expand Retractive force = The force of the crosslinked structure that counterbalances the swelling force Equilibrium = When the swelling force and retractive force become equal Degree of swelling = Influences solute diffusion coefficient, polymer surface properties, optical properties, and mechanical properties</p> Signup and view all the answers

    Match the following hydrogels with their examples:

    <p>Highly swollen hydrogels = Cellulose derivatives, poly(vinyl alcohol), poly(N-vinyl 2-pyrrolidone), PNVP, poly(ethylene glycol) Moderately or poorly swollen hydrogels = Poly(hydroxyethyl methacrylate) (PHEMA) and derivatives Controlled release drug delivery devices = Application of highly swollen hydrogels Blood-compatible coatings = Application of highly swollen hydrogels to prevent protein deposition and platelet adhesion</p> Signup and view all the answers

    What type of hydrogel classification involves more than three types of mers?

    <p>Multipolymer hydrogels</p> Signup and view all the answers

    What is the term for a polymer comprising two or more networks which are at least partially interlaced on a molecular scale but not covalently bonded to each other?

    <p>Interpenetrating Polymer Network (IPN)</p> Signup and view all the answers

    What is the ideal network structure involving tetrafunctional covalent crosslinks called?

    <p>Ideal network with tetrafunctional covalent crosslinks</p> Signup and view all the answers

    What is the term for the connections between chains in a hydrogel?

    <p>Crosslink or junction</p> Signup and view all the answers

    What is the classification based on ionic charges for hydrogels?

    <p>Neutral, Anionic, Cationic, or Ampholytic</p> Signup and view all the answers

    What forces can form non-covalent physical hydrogels?

    <p>Assembly systems</p> Signup and view all the answers

    What is the term for a polymer network that absorbs water and expands after polymerization?

    <p>Hydrophilic gel</p> Signup and view all the answers

    What type of polymer yields a hydrogel when lightly crosslinked?

    <p>Hydrophilic polymer</p> Signup and view all the answers

    What is the purpose of blood-compatible coatings using hydrogels?

    <p>Prevents protein deposition and platelet adhesion</p> Signup and view all the answers

    What can be controlled by polymer composition and crosslink density in hydrogels?

    <p>Swelling ratio</p> Signup and view all the answers

    What is the term for the ratio of the weight of swollen sample to that of the dry sample expressed as percentage?

    <p>Swelling ratio</p> Signup and view all the answers

    What is the term for a mixture of two or more preformed polymer networks that is NOT an Interpenetrating Polymer Network (IPN)?

    <p>Not an IPN</p> Signup and view all the answers

    Explain the difference between covalently crosslinked hydrogels and non-covalent physical hydrogels, and provide an example of each type.

    <p>Covalently crosslinked hydrogels are formed by covalent bonding between polymer chains, while non-covalent physical hydrogels are formed by molecular entanglements and/or secondary forces such as van der Waals, hydrogen bonding, or hydrophobic forces. An example of covalently crosslinked hydrogel is pHEMA + EGDMA (Ethylene Glycol Dimethacrylate), used for soft contact lenses. An example of non-covalent physical hydrogel is JELL-O, made from a naturally derived polymer collagen.</p> Signup and view all the answers

    What are the different types of interactions that can cause crosslinks in hydrogels, and how do they contribute to the formation of hydrogels?

    <p>The different types of interactions that can cause crosslinks in hydrogels are covalent bonding between polymer chains, hydrogen bonds, van der Waals interactions, and ionic interactions. Covalent bonding leads to the formation of covalently crosslinked hydrogels, while hydrogen bonds, van der Waals interactions, and ionic interactions contribute to the formation of non-covalent physical hydrogels.</p> Signup and view all the answers

    What is the relationship between crosslink density and the properties of hydrogels, and how does it impact their applications in medicine?

    <p>Crosslink density in hydrogels is related to their swelling behavior, mechanical strength, and biocompatibility. Higher crosslink density generally leads to reduced swelling, increased mechanical strength, and improved biocompatibility. This relationship impacts the design of hydrogels for specific medical applications, such as drug delivery, tissue engineering, and wound healing, where controlled swelling, mechanical properties, and biocompatibility are crucial factors.</p> Signup and view all the answers

    Study Notes

    • Covalent bonds can form crosslinks between polymer chains in hydrogels, leading to a rigid structure
    • Non-covalent interactions such as hydrogen bonding, hydrophobic interactions, and electrostatic interactions can also create crosslinks, resulting in a more flexible structure

    Hydrogel Types

    • Physical hydrogels are formed by non-covalent interactions and are typically reversible
    • Chemical hydrogels are formed by covalent bonds and are generally irreversible
    • Interpenetrating Polymer Networks (IPNs) are made up of two or more polymer networks that are physically entangled but not covalently bonded
    • Semi-IPNs are similar to IPNs but contain one network that is physically entangled with a pre-existing network.
    • Blends are mixtures of two or more preformed polymer networks which are NOT an Interpenetrating Polymer Network (IPN).
    • Multi-component hydrogels contain more than three different types of mers.

    Hydrogel Properties

    • Crosslink density refers to the number of crosslinks per unit volume of the hydrogel.
    • Swelling ratio is the ratio of the weight of a swollen hydrogel to that of the dry sample, expressed as a percentage.
    • Mechanical properties of hydrogels, such as strength and elasticity, can be controlled by polymer composition and crosslink density.

    Hydrogel Applications

    • Hydrogels are used in tissue engineering scaffolds, particularly for artificial tendons and cartilage where their biocompatibility and ability to mimic natural tissue are beneficial.
    • Hydrogels are used in blood-compatible coatings to prevent blood clotting.

    Ideal Network Structure

    • The ideal network structure for a hydrogel involves tetrafunctional covalent crosslinks, creating a regular and robust network.

    Terminology

    • Crosslinks: refer to the connections between chains in a hydrogel that give it its structure.
    • Hydrogel: A polymer network that absorbs water and expands after polymerization.
    • The degree of swelling refers to the amount of water absorbed by a hydrogel.

    Forces in Hydrogel Swelling

    • Osmotic pressure drives water into the hydrogel, pushing the polymer chains apart.
    • Hydrogen bonding between the water molecules and the polymer chains helps maintain the swollen state.
    • Electrostatic interactions can also contribute to swelling, especially in hydrogels with charged polymer chains.

    Hydrogels in Different Fields

    • Biocompatible hydrogels are used in drug delivery systems and tissue engineering scaffolds, which are designed to be compatible with biological tissues.
    • Injectable hydrogels can be administered through a syringe, allowing for minimally invasive delivery.
    • Self-healing hydrogels can repair themselves after damage, which can be beneficial for applications such as wound healing and tissue regeneration.

    Examples of Hydrogels

    • Alginate hydrogels are used in tissue engineering scaffolds and drug delivery.
    • Collagen hydrogels are used in wound healing and tissue regeneration.
    • Poly(ethylene glycol) (PEG) hydrogels are used in drug delivery and biocompatible coatings.

    Difference Between Covalently Crosslinked and Non-Covalent Physical Hydrogels

    • Covalently crosslinked hydrogels are formed by permanent covalent bonds between polymer chains, making them more stable and robust. They are typically used in applications where strength and durability are essential. Example: PEG hydrogel crosslinked with a chemical reagent.
    • Non-covalent physical hydrogels are formed by temporary interactions such as hydrogen bonding or electrostatic interactions, making them more flexible and responsive to environmental changes. They are suitable in applications where reversible behavior is required or strength is not a primary concern. Example: Gelatin hydrogel formed through hydrogen bonding.
    • Higher crosslink density leads to:
      • Increased stiffness and strength
      • Reduced swelling capacity
      • Reduced permeability to molecules
      • Increased resistance to degradation
    • Lower crosslink density leads to:
      • Increased flexibility and elasticity
      • Enhanced swelling capacity
      • Increased permeability to molecules
      • Reduced resistance to degradation

    Applications in medicine

    • Controlled drug delivery: Hydrogels can encapsulate drugs and release them at a controlled rate, ensuring sustained therapeutic effects.
    • Tissue engineering: Hydrogels act as scaffolding materials that support cell growth and tissue regeneration.
    • Wound healing: Hydrogels can promote wound healing by providing a moist environment and protecting the wound from infection.
    • Biocompatible coatings: Hydrogels can be used as coatings for medical devices, improving their biocompatibility and reducing inflammation.

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    EBME 306-Sen Gupta-Polymeric Biomaterials-Lecture 5-Fall 2023.pptx

    Description

    Test your knowledge on hydrogels in medicine with this quiz based on the lecture by Anirban Sen Gupta, Ph.D. Explore the properties and crosslinking mechanisms of hydrogels, and assess your understanding of their applications in the medical field.

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