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Application of gold nanoparticles in tumor diagnosis and treatment


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Title: Application of gold nanoparticles in tumor diagnosis and treatment

Application of gold nanoparticles in tumor
diagnosis and treatment
  • In recent years, nanomaterials and nanotechnology
    have increasingly entered the clinical
    application stage. Gold nanoparticles have very
    unique physical and chemical properties. And gold
    nanoparticles are relatively safe, easy to
    prepare, and very stable. In addition to the
    small size effects, surface effects, quantum size
    effects, macro quantum tunnel effects, and
    dielectric effects of nanoparticles, gold
    nanoparticles also have unique electrical,
    optical, magnetic, catalytic effects. Therefore,
    gold nanoparticles have been widely used in the
    filed of biomedicine. In the treatment of tumors,
    gold nanoparticles have better penetrating power
    than traditional drugs, and their risks in
    diagnosis and treatment are lower than
    traditional drugs.

Structure and Properties of gold nanoparticles
  • Gold nanoparticles exhibit unique physical and
    chemical properties due to their different shapes
    and sizes. The gold nuclei of gold nanoparticles
    are essentially inert and non-toxic. The
    synthesis of gold nanoparticles is relatively
    easy, and the diameter range is controllable,
    generally in the range of 1 to 150 nm. Gold
    nanoparticles with different properties and sizes
    can control the release of drugs in different
    parts, so it is a good drug carrier. Various
    shapes of gold nanoparticles have been developed
    to meet different therapeutic needs.Gold
    nanospheres (AuNPs) are gold nanoparticles
    produced by reduction of chloroauric acid, with
    diameters ranging from 1 to more than 100 nm, and
    they are mainly used for imaging and
    radiosensitization. Gold nanoshells (AuNSs) are
    spherical with diameters ranging from 50 to 150
    nm. The structure of the gold nanoshell includes
    a core of silicon dioxide and a thin gold shell.
    The optical properties of AuNSs can be adjusted
    by changing the diameter of the core and the
    thickness of the shell wall. Gold nanorods
    (AuNRs) are usually synthesized by the reaction
    of chloroauric acid on gold seeds using
    cetyltrimethylammonium bromide (CTAB) as a
    stabilizer. The size of AuNRs is usually 25-200
    nm. The wavelength of the absorption peaks of
    AuNRs can be changed by changing the ratio of the
    length and diameter of these particles (ie, the
    aspect ratio). There are also other forms of gold
    nanoparticles, such as nanocages and hollow gold

Application of gold nanoparticles in tumor
  • One of the differences between tumor cells and
    normal tissue cells is the difference in cellular
    metabolic activity. For example, in liver cancer
    cells, breast cancer cells, or melanoma cells,
    protein kinase (PKCa) is either overexpressed or
    has abnormal activity. Protein kinases can
    phosphorylate specific substrate peptides,
    resulting in changes in the net charge carried by
    the substrate peptides. When the substrate
    peptide and nanogold are mixed, the stability of
    the nanogold colloid is affected by the net
    charge before and after the substrate peptide is
    phosphorylated. The surface charge layer of the
    nanogold is destroyed by the large net charge of
    the substrate peptide, which will cause colloid
    aggregation Therefore, the activity or expression
    of protein kinase can be indirectly determined by
    whether or not nanogold is aggregated, so that
    tumor cells and normal tissue cells can be
    distinguished. Imaging with gold nanoparticles in
    the visible spectrum can only be applied to
    cancers on the skin surface. Optical imaging of
    most solid tumors in vivo needs to be performed
    in the near infrared spectral region of 780 to
    2526 nm (especially 780 to 1100 nm). Changing the
    size, shape and composition of gold
    nanoparticles, or modifying the surface of gold
    nanoparticles can make the nanoparticles have
    high surface plasmon resonance absorption and
    scattering capabilities in the near-infrared
    spectral region. By connecting them with specific
    biological targeting molecules, gold
    nanoparticles can become a very effective imaging
    agent for tumor imaging. Studies have found that
    PEGylated gold nanoparticles, gold cages and gold
    rods all have good stability, biocompatibility,
    biodispersity, and osmotic retention effects, and
    can accumulate in large quantities at tumor
    sites. In the near-infrared spectral region,
    these types of gold nanoparticles have suitable
    local surface plasmon resonance peaks, so they
    can clearly develop tumor tissue.

Application of gold nanoparticles in tumor
  • As a drug carrier, gold nanoparticles can improve
    the pharmacokinetics of drugs, thereby reducing
    non-specific side effects and achieving targeted
    drug delivery at higher doses. Gold nanoparticles
    can also be used in thermotherapy treatments. The
    mechanism of hyperthermia treatment involves the
    thermal stress response of cells at 42-47 C,
    which causes the activation of cells and the
    activation of degradation mechanisms inside and
    outside the cell. The negative effects of
    hyperthermia on cells include misfolding and
    aggregation of proteins, changes in signal
    transduction, cell apoptosis, changes in pH,
    reduced perfusion and tumor oxygenation, etc.
    Gold nanoparticles such as gold nanorods (AuNRs)
    or gold nanoshells (AuNSs) have obvious
    advantages in the absorption and scattering of
    near-infrared light (wavelengths from 650 to 900
    am). When exposed to electromagnetic radiation,
    especially near-infrared light, gold
    nanoparticles can generate heat through surface
    plasmon resonance effects. Because the peak of
    the absorption wave of gold nanoparticles is in
    the visible light range (450-600 nm), the
    absorption of near-infrared light by normal
    tissues is very small. Stimulating gold
    nanoparticles with near-infrared laser light can
    induce heat generation and hardly damage normal
    tissues. Therefore, gold nano-mediated
    photothermal therapy has the advantages of strong
    specificity and less trauma compared with
    traditional tumor treatment.

  • Gold nanoparticles have unique physical and
    chemical properties and have been a hot spot in
    tumor diagnosis and treatment. The application of
    gold nanoparticles in the detection of tumor
    markers and the imaging of tumors is the focus of
    researchers' attention. However, more studies are
    needed on the metabolism of gold nanoparticles in
    the body and its effect on normal cell activity,
    especially on gene expression or regulation.
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