Radiolabeled Aptamers for Bioimaging Applications in Oncology and Infectious Diseases

Radiolabeled aptamers are promising molecular probes for bioimaging because of their potential for high specificity, stability, and rapid clearance from nontarget tissues. They are single-stranded oligonucleotides labeled with radionuclides such as technetium-99m (⁹⁹ᵐTc), fluorine-18 (¹⁸F), and gallium-68 (⁶⁸Ga) to enable precise imaging via single-photon emission computed tomography (SPECT) and positron emission tomography (PET). The versatility of radiolabeling strategies can provide opportunities to enhance biostability and pharmacokinetics while improving imaging sensitivity. In cancer theranostics, radiolabeled aptamers can allow early detection and treatment as well as facilitate effective monitoring of therapeutic responses. The applications of radiolabeled aptamers extend to infectious disease imaging, enabling real-time tracking of infections. Despite these advances, challenges such as rapid renal clearance, immunogenicity, and the need for clinical validation persist, catalyzing further research focused on enhancing the stability of radiolabeled aptamers, improving radiolabeling efficacy, and optimizing biodistribution. Emerging strategies, including nanoparticle conjugation and hybrid bioimaging, offer a great perspective for advancing the field. This article highlights recent advancements in radiolabeled aptamers in terms of their development, bioimaging applications, and research directions to address their limitations.