Aptamers as Versatile Ligands for Biomedical and Pharmaceutical Applications

Abstract

Aptamers are a class of targeting ligands that bind exclusively to biomarkers of interest. Aptamers have been identified as candidates for the construction of various smart systems for therapy, diagnosis, bioimaging, and drug delivery due to their high target affinity and specificity. Aptamers are accounted as chemical antibodies that can be readily linked to drugs, sensors, signal enhancers, or nanocarriers for functionalization. Use of aptamer-guided medications, especially nanomedicines, has resulted in encouraging outcomes compared to those use of aptamer-free counterparts. This article reviews recent advances in the use of aptamers as targeting ligands for various biomedical and pharmaceutical purposes. Special interests focus on aptamer-based theranostics, biosensing, bioimaging, drug potentiation, and targeted drug delivery.

Keywords: aptamer; biomedical imaging; biosensor; drug delivery; theranostics.

Figure 1

Aptamer structure, characteristics, and functional illustration for biomedical applications.

Figure 2

Aptamers as theragnostic agents for various diseases by targeting to etiological loci and interfering with pathological processes.

Figure 3

Aptamer-mediated biosensors for analysis using fluorescence, chemiluminescence, electrochemistry, or immunoluminescence.

Figure 4

Design rationale and imaging methods for aptamer-facilitated biomedical imaging (A) with a demonstration of PET molecular imaging for HER2 in cancer (B). The illustration was used with permission from Zhu G, Zhang H, Jacobson O, et al. Combinatorial screening of DNA aptamers for molecular imaging of HER2 in cancer. Bioconjug Chem. 2017;28(4):1068–1075. doi:10.1021/acs.bioconjchem.6b00746, Copyright (2017) American Chemical Society.

Figure 5

Synergy and attenuation of therapeutic agents through three aptamer-related approaches: co-administration of a therapeutic aptamer and a drug, development of an aptamer-drug conjugate, and construction of an aptamer-RNA chimera.

Figure 6

Various organic and inorganic nanocarriers functionalized using aptamers for targeted drug delivery, and commonly used strategies for aptamer conjugation with nanocarriers.