Aptamer as the cell-targeting probe and intracellular detector (review article)
,1 Nasrin mohajeri
,2 Mohammad pourhassan moghaddam
,3 Fatemeh radnia
,4 Nosratollah zarghami
1. Department of Medical Biotechnology, Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences
2. Department of Medical Biotechnology, Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences
3. Department of Medical Nanotechnology, Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences
4. Department of Medical Biotechnology, Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences
5. Department of Medical Biotechnology, Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences
aptamers are single-stranded oligonucleotides (usually 20–80 nucleotides) which serve as different molecular detection through creating three-dimensional folding self. they are preferred as diagnostic probes compared to antibodies due to characteristics such as minimal bioavailability, appropriate stability and high biocompatibility. by increasing the application of aptamers in the field of diagnosis and treatment, they have captured attention to optimize molecular targeting in the live cell. the aptamers internalization is used for two different approaches. at first, aptamers in conjunction with drug, nanoparticles (np), and sirna would create targeted delivery agents for drug delivery, gene therapy and imaging respectively via targeting cell surface. secondly, the aptamers can also detect intracellular targets in order to monitor the activity of the cells through the traceability of metabolites, developing the live cell imaging and study of rna expression level.
in this article, aptamers are assessed as tools for the introduction of np, drug, toxin and sirna into cells. the different nps such as qd, graphene, ag, gold and ce6 are conjugated with aptamers for the signaling purpose, typically by the edc/nhs catalyst. the conjugations are analyzed with electrophoresis, flow cytometer and fluorescent microscopy. it has been reviewed that the intracellular targets such as atp, nadh, interfron_gama, mrna, microrna and glutathione are successfully detected with aptamers. furthermore, the biochemical and physical strategies have been developed for the internalization of aptamers. the physical delivery strategy includes electroporation and microinjection and there is the increasing number of endocytic pathways that the internalization via clathrin-dependent endocytosis is most accepted
as a result of this study, found that targeting efficiency between 30 -70 percentage and specificity of the cell-targeting aptamers could be suitable which are evaluated by flow cytometry assay and confocal laser scanning microscopy. the data demonstrated a high fold (around 70-fold) enhancement in the binding of bioconjugates (nanoparticle-aptamer) compared with nonconjugated in the target cells. the number of attached aptamer per nanoparticle is different based on size and type of the nanoparticle. the gene expression changes caused by drug and gene delivery was confirmed by rt-pcr method. these outcomes provide a promising outlook for aptamer’s application in the field of imaging, drug delivery, gene therapy and biosensing.
Finally, in spite of the several challenges and further limitations in this emerging field, there is a promising perspective for using cell-targeting aptamers and internalizing aptamers.
Cell-targeting aptamer, internalizing aptamer, intracellular detection