RUDN University nanotechnologists have studied the use of gold nanoparticles for the diagnosis and treatment of cancer

The researchers studied about 200 scientific articles no older than 2010, which were found in the keywords “gold nanoparticles”, “cancer”, “cancer treatment”, “targeted drug delivery” and “diagnostics”. After collecting data, scientists analyzed how the shape and size of gold nanoparticles affect the penetration of nanoparticles into the cell, the ability to linger in it, as well as cytotoxicity.

“Many reviews highlight the various benefits of gold nanoparticles in cancer therapy, and also foresee a great future for diagnostic methods using them. We reviewed the latest scientific advances in these areas, but since biocompatibility and cytotoxicity depend on the size and shape of the nanoparticles, we decided to consider these two parameters as well. In addition, we studied the features of the use of gold nanoparticles for targeted drug delivery, photodynamic and ultrasonic chemical therapy and their potential for medical examinations. We also discussed the limitations that modern oncology needs to overcome in order to use gold nanoparticles most effectively — Andrey Vodyashkin, Engineer, Institute of Biochemical Technology and Nanotechnology, RUDN University.

The analysis showed that usually nanoparticles less than 200 nmare used in therapy,which are easier to pass through the cell membrane. At the same time, too small (less than 6 nm)nanoparticles are quickly released through the kidneys and do not have time to act on the tumor. For particles in the range of 10-100 nm, the half-life increases with their size, which affects the dosage and duration of action of the drug. Penetrating into the cell is best obtained in spherical particles, followed by particles in the form of rods and stars. In cytotoxicity, nanosellersbecame champions, the average results were shown by nanostars,and in third placewere nanospheres.

Nanoparticles can help in the active and passive delivery of drugs based on peptides or nucleic acids, as well as become part of hybrid preparations based on gold. Gold particles measuring 25-50 nanometers are best absorbed into the cell, but for some drugs, scientists have managed to bind up to 100 molecules to a nanoparticlewith a diameter of 2 nm.But the nanoparticles can themselves act as part of the drug — in photodynamic therapy, they increase the sensitivity of cancer cells to light and kill them, because they are able to absorb radiation close to infrared. This method does not require surgery. It is suitable for treating tumors near the surface of the body — toa depth where the skin is able to transmit light ofwavelengths of 650–950 nm. Another approach to cancer therapy uses ultrasound, which causes bubbles to appear on the rough surface of the nanoparticles. This creates an evaporation effect and destroys cancer cells nearby.

Gold nanoparticles help to clarify the location, size and other characteristics of tumors, the presence of various substances and components in them. If you wrap graphene oxide nanoparticles in gold, you can combine intracellular imaging with the delivery of a drug that attaches to this nanoparticle. Gold absorbs ultrasonicwaves, soit can be used in photoacoustic diagnostics, which is used to look for melanoma and examine the growth of vessels around the tumor. Nanoparticles will also be useful for creating new diagnostic methods, such as DNA biosensors.

“Despite the fact that the size, shape and even the charge of gold nanoparticles strongly affect their action, we did not find a direct connection between these parameters and the effectiveness of therapy. What’s more, each type of tumor requires a personalized approach to match the characteristics of the nanoparticles that are best suited to a particular organ and will be safe for the patient. A balance must be struck between toxicity to the tumor and safety to the patient. We should pay more attention to how nanoparticles are distributed throughout the body, because on average only 0.7%, and in exceptional cases, up to 5% of them reach cancer cells. In addition, we lack clinical trials, of which there were only 15 as of September 5, 2021. This greatly limits the use of gold nanoparticles in medicine,” Andrey Vodyashkin, Engineer, Institute of Biochemical Technology and Nanotechnology, RUDN University.

The results are published in the journal ChemEngeneering.