Gene Therapy and Viral Vectors Lecture 10

Nanorods Nanorods are morphology of nanoscale objects. Each of their dimension ranges from 1–100 nm. Nanorods may be synthesized from metals or semiconducting materials (germanium, silicon). One way for synthesis of nanorods is produced by direct chemical synthesis. The combinations of ligands (capping agents) act as shape control agents and bond to different facets of the nanorod with different strengths. This allows different faces of the nanorod to grow at different rates, producing an elongated object.

Capping/stabilizing agents: ligands, surfactants, polymers, dendrimers, biomolecules The use of coating nanoparticle with surfactant or polymer is to prevent aggregation of the particles due to nanoparticles high surface energy. It also controls the size of the particles during synthesis process. Capping of nanoparticles can be checked using TEM (Transmission Electron Microscope)

Capping agents Capping agent would help preventing the nanoparticles from growth. Final product could be either a solid or liquid. Stabilizing agent could be used to prevent agglomeration of the nanoparticles. Here too, the final product could be either a solid or liquid. Dispersing agent also helps in preventing agglomeration, but the final product must be a liquid. There may be just one material, for example the PEG, which could serve all the three roles mentioned above. That is the reason why all these terms are being used by the researchers in common. PEG: Poly Ethylene Glycol

Addition of biomolecules After synthesis, the stabilizing agents surrounding the nanoparticles can be replaced by other molecules usually by ligand exchange reactions. Biomolecules such as DNA/RNA, oligonucleotides (i.e. siRNA, ssDNA), peptides and antibodies, fluorescent dyes, polymers, drugs, tumoral markers, various enzymes and other proteins, that are easily attached to the nanoparticles’s surface. In addition, ligands can also be linked to the shell of stabilizing agents. One of the most common applications is the linkage of amino groups in biological molecules with carboxyl groups at the free ends of the stabilizing agents.

Photothermal therapy using nanorods In photothermal therapy a photosensitizer is excited with specific band light (electromagnetic radiation most often in infrared wavelengths) . This activation brings the sensitizer to an excited state where it then releases vibrational energy (heat), which is what kills the targeted cells. https://www.youtube.com/watch?v=Jebxo cVt4f0

Acute Kidney Injury Acute kidney injury, which occurs when the kidneys become unable to filter waste products from the blood, develops rapidly over a few hours or a few days. It is common in people who are hospitalized, particularly in those critically ill people or who have had heart surgery. To date, there have not been any sensors that can easily detect if a person will experience acute kidney injury.

Gold nanorods that detect proteins can be used for kidney disease detection This process involves attaching the target proteins to the surface of the nanorods, then adding small molecules around the proteins to form a polymer layer around the outside of the nanorods. The target proteins are removed to leave cavities on the surface of the nanorods, which are the artificial antibodies. When the nanorods with the artificial antibodies are exposed to a substance, such as urine, that contains the target protein, those proteins settle into the cavities, similar to a puzzle piece fitting into a jigsaw puzzle.

Srikanth Singamaneni, PhD, assistant professor of engineering, along with Evan Kharasch, MD, PhD, and Jerry Morrissey, PhD, at Washington University School of Medicine, have developed a biomedical sensor using gold nanorods designed to detect the elevation of the protein neutrophil gelatinase-associated lipocalin (NGAL), a promising biomarker for acute kidney injury, in urine.

Drug delivery https://www.youtube.com/watch?v=RBjW wlnq3cA