Radiolabeling of Nucleic Acid Aptamers for Highly Sensitive Disease-Specific Molecular Imaging

Abstract

Aptamers are short single-stranded DNA or RNA oligonucleotide ligand molecules with a unique three-dimensional shape, capable of binding to a defined molecular target with high affinity and specificity. Since their discovery, aptamers have been developed for various applications, including molecular imaging, particularly nuclear imaging that holds the highest potential for the clinical translation of aptamer-based molecular imaging probes. Their easy laboratory production without any batch-to-batch variations, their high stability, their small size with no immunogenicity and toxicity, and their flexibility to incorporate various functionalities without compromising the target binding affinity and specificity make aptamers an attractive class of targeted-imaging agents. Aptamer technology has been utilized in nuclear medicine imaging techniques, such as single photon emission computed tomography (SPECT) and positron emission tomography (PET), as highly sensitive and accurate biomedical imaging modalities towards clinical diagnostic applications. However, for aptamer-targeted PET and SPECT imaging, conjugation of appropriate radionuclides to aptamers is crucial. This review summarizes various strategies to link the radionuclides to chemically modified aptamers to accomplish aptamer-targeted PET and SPECT imaging.

Updates on Aptamer Research

“…The confocal images also confirmed the specificity of 18 F-labelled aptamers to HER2-positive cells [165]. For strategies employed in the development of aptamer-based SPECT and PET imaging we refer the readers to an informative review by Hassanzadeh et al [166].…”

<p>Aptamers as Versatile Ligands for Biomedical and Pharmaceutical Applications</p>

“…Ligand-mediated non-invasive imaging allows for visual observation of diseases at the cellular and molecular levels. 41 This technique provides high accuracy and predictability for early diagnosis and treatment, resulting in improved prognosis. Aptamer-aided biomedical imaging can be achieved through direct or activatable optical imaging by linking an aptamer to a fluorescent molecule or a fluorescent mediator (NPs or quantum dots), or through other tomographic techniques, such as MRI, ultrasound, and PET ( Figure 4).…”

Predicting Future Prospects of Aptamers in Field-Effect Transistor Biosensors

“…Intensive research on the fundamentals and principles of this area has attracted more investments [96][97][98] whilst binding affinity has also been strengthened at all cost [19,99]. Consequently, these breakthroughs have been accompanied by an expansion and improvement of the application of aptamers to small molecules in areas such as drug delivery [100] and molecular imaging [101], particularly in sensing technology where they are combined with electrochemistry, surface plasmon resonance, optical fibers, quantum dots, field-effect transistors, fluorescence and a variety of other techniques used to monitor contaminants, metal ions, hormones, explosives, toxins, drugs, antibiotics and pesticides [29,[102][103][104][105][106][107][108].…”