Experts are constantly exploring new ways to develop more effective treatments against cancer. One such approach is using amino acid nanoparticles showing potential anticancer activity.

Amino Acid Nanoparticles Crosslinked by UV Irradiation Demonstrate Enhanced Anticancer Activity
(Photo: Pexels/ Edward Jenner)

Amino acids, like tryptophan and tyrosine, are the basic building blocks that make up proteins. Since these biomolecules have different chemical groups on each end and side chain, they can form a chain by creating an amide bond. However, these weak linkages can degrade easily under certain physiological conditions. This is where Fmoc-protected amino acids come into play.

What are Fmoc-Protected Amino Acids?

Fluorenylmethoxycarbonyl (Fmoc) refers to a set of urethane-protecting groups used in organic synthesis. It is typically introduced by reacting the amine with fluorenylmethoxycarbonyl chloride (Fmoc-Cl).

In peptide synthesis, the protection of amino acids is crucial since they serve as important raw materials for solid-phase synthesis. All amino acids contain alpha-amino and carboxyl groups, and most of them have active side chains. These active groups must be protected during the synthetic reaction. In this process, the protecting groups must remain stable without side reactions since they are removed after the completion of the reaction.


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Photocrosslinked Amino Acid Nanoparticles

In a recent study, a team of researchers led by Dr. Eijiro Miyako from Japan Advanced Institute of Science and Technology (JAIST), Dr. Alberto Bianco, and Dr. Cécilia Ménard-Moyon from the Centre National de la Recherche Scientifique (CNRS), France has crosslinked Fmoc-protected amino acids. This was possible by employing UV light at 254 nanometers and riboflavin-mediated crosslinking at 365 nanometers.

The team wanted to develop new self-assembled amino acid-based nanoparticles that can be triggered through multiple mechanisms. The result of their study was discussed in the paper "Photocrosslinked Co-assembled Amino Acid Nanoparticles for Controlled Chemo/photothermal Combined Anticancer Therapy."

The self-assembled amino acids used in this study were crosslinked dimers of tyrosine and tryptophan. The resulting nanoparticles were then loaded with an anticancer drug called doxorubicin. A tannic acid-iron complex was used as the outer layer of the coating to increase the stability of the nanoparticles. This layer can degrade inside the cells through the glutathione enzymatic release or by pH difference in the tumor microenvironment. The tannic acid coating shows potential in photothermal anticancer therapy by allowing the external light to increase the local temperature around the cancer tissue.

Dr. Miyako and his colleagues studied the synthesized amino acid nanoparticles regarding their stability, structural integrity, and drug release under various pH conditions. Cell culture methods also investigated the cellular uptake, functional profile, and biocompatibility of self-assembled amino acid nanoparticles. Finally, they assessed the anticancer efficacy of synthesized particles in tumor-bearing mice.

The combined photothermal therapy and chemotherapy approaches showed excellent anticancer activity, thanks to the tannic acid coating. The study also revealed minimal drug release under a pH of 7.4, indicating that stable coating is crucial for in vivo delivery. The tumor growth inhibition observed in mice demonstrated promising anticancer effects without observable side effects.

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