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Role of Protein Adsorption - Coggle Diagram

- - - - Amino Acids
        
        Human body requires 20 standard Amino Acids to grow, repair tissues, and function properly
        
        Divided into 3 main categories:
        
        Essential Amino Acids (9)
        
        The body cannot manufacture these.
        
        Must be obtained through diet or supplements
        
        Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, Valine
        
        Nonessential Amino Acids (5)
        
        Body can synthesize these internally
        
        Alanine, Asparagine, Aspartic Acid, Glutamic Acid, Serine
        
        Conditionally Essential Amino Acids (6)
        
        Normally Non-essential, but become essential during periods of illness, stress, rapid growth, or trauma
        
        Arginine, Cysteine, Glutamine, Glycine, Proline, Tyrosine
  - - - Amino Acid Sequence
    - - Regularly repeating local structures stabilized by hydrogen bonds
    - - Overall shape of a single protein molecule
    - - Structure formed by several protein molecules
        
        Called polypeptide chains
- - - - Albumin, Fibrinogen, & Fibronectin
- - - - Keep the blood from leaking out of blood vessels
      - Carry some medicines & other substances through the blood
      - Important for tissue growth & healing
      - More than half of the protein in blood serum
    - - 4 Types:
        
        Alpha-1
        
        High-Density Lipoprotein (HDL)
        
        "Good cholestestorol" is included in this fraction
        
        Alpha-2
        
        Haptoglobin
        
        Binds to hemoglobin
        
        Included in this fraction
        
        Beta
        
        Help carry substances, such as iron, through the bloodstream & help fight infection
        
        Gamma
        
        Antibodies
        
        Help prevent & fight infection
        
        Bind to foreign substances & destroy them
    - - Hormones, Enzymes, & Antibodies
- - - - Water molecules & ions from body fluids interact w/ biomaterial surface within milliseconds
        
        Forms a hydration shell that depends on the material's chemical & physical properties
    - - Free proteins from blood or interstitial fluid land on surface within seconds to minutes
        
        Smaller, fast-moving proteins arrive first, such as Albumin
        
        Later replaced over time by larger or higher-affinity proteins
        
        Called the Vroman effect
    - - Once adsorbed, protein molecules can change their 3D shape
        
        Due to surface energy, hydrophobic interactions, or electrostatic forces
        
        This unfolding can expose hidden active binding cites that cells can recognize
    - - Cells do not touch bare biomaterial
        
        Instead, they bind to newly formed protein layer via specific cell-surface receptors called integrins
        
        This dictates whether the body integrates the material (bone growth, tissue healing) or rejects it (inflammation, blood clotting, or fibrous encapsulation)
  - - - Surface Chemistry
        
        Plays an important role in determining adsorbed protein conformation
        
        As well as rates of adsorption & the amount of protein adsorbed
        
        Through interaction between functional groups & those of the protein itself
        
        Chemical nature of the surface can be modified to induce greater protein-surface affinity
        
        By either electrostatic or hydrophobic interactions
      - Topography
        
        Architecture of the surface may be used to manipulate protein shape & form upon adsorption
        
        Atomic force microscopy & SCM to determine topography
        
        Topography on the order of nanometres has been shown to impact the conformation of bound proteins
        
        Architecture of the surface may be used to manipulate protein shape & form upon adsorption
        
        Not fully explored, but a critical factor in understanding scaffold architecture
    - - Most info is based on in-vitro studies
      - Most in-vivo studies are conducted for applications like:
        
        Wound healing
        
        Osseointegration
      - Fate of implants is determined by the response of cells to the implant material's surface
        
        Positive, like tissue regen & osseointegration
        
        Negative, like chronic inflammation & fibrous encapsulation
        
        Fibrous encapsulation = immune response where body surrounds foreign object in scar tissue
      - Initial presentation of a foreign material to cells is a layer of spontaneously adsorbed proteins
        
        Their composition & bioactivity provide a biological interpretation of underlying physiochemical properties
      - Adsorption of proteins such as vitronectin and fibronectin is a key factor several processes
      - Interaction of fibrinogen with implant surfaces is critical in-vivo
        
        It has involvement in clot formation & platelet activation
      - Only in early stages of understanding
        
        Understanding composition of the interface at the relevant time point is crucial for predicting or controlling living tissue response to implanted surfaces
        
        Understanding formation & function of the adsorbed protein layer would provide important link btwn biomaterial surface properties & biological responses
- - - - Minimizes contact w/ the aqueous phase
  - - - Surface-protein interactions are not well understood
      - Plays a fundamental role in protein adsorption
      - Properties of protein over-layers can be altered by the underlying surface chemistry of a material
  - - - Sorbent = insoluble material that recovers liquids or gases through absorption
- - - - Which proteins are adsorbed & in what quantities
    - - Functionality, as determined by conformation, orientation, etc.