Medical aspects

Even though there is no doubt that peptide aptamers are potential rivals of traditional antibodies in medicine and therapy, some hurtles have to be defeated before clinical implementation will be possible.

The peptide aptamer needs

• an effector mechanism that can either activate the immune system or in some how kill the antigen or cell. Traditional antibodies have a Fab region, that bind to microbes of which they have specificity. Activation of the immune respons is conducted through their Fc region that interacts with Fc receptors on cell surfaces of lymphocytes and/or other effector cells of the immune system. Such a effector mechanism or something like it have to be attached to the peptide aptamer.
• a suitable size to avoid an respons from the human immune system. The bigger molecule the larger risk of immunogenicity. If the immune system develops immunization against the peptide aptamer it will not have any function at all.
• adjustable half-life so it can be used as a treatment for both quickly directed therapy and for chronic diseases. If the target is cancer cells or something that just needs to be detected, then there is no need for a very long half-life. But peptide aptamers targeted at chronic diseases have to have a very long degradation time.

How can peptide aptamers treat disease?

• By attaching small gold nanoparticles (sAuNPs) to the peptide aptamer it would be possible to detect the aptamer inside the body and target fx radiotherapi: Recent studies have proved small gold nanoparticles (sAuNPs) as excellent vehicles for drug delivery and cancer therapy. sAuNPs are proven as excellent vehicles especially because of their high biocompatibily, large surface-to-volume ratio and strong diffusivity. Reference: Kim CS, et al. Cellular imaging of endosome entrapped small gold nanoparticles, 2015 Jun 10;2:306-15. doi: 10.1016/j.mex.2015.06.001. (Link)