Aptamers: versatile molecular recognition probes for cancer detection

Abstract

In the past two decades, aptamers have emerged as a novel class of molecular recognition probes comprising uniquely-folded short RNA or single-stranded DNA oligonucleotides that bind to their cognate targets with high specificity and affinity. Aptamers, often referred to as “chemical antibodies”, possess several highly desirable features for clinical use. They can be chemically synthesized and are easily conjugated to a wide range of reporters for different applications, and are able to rapidly penetrate tissues. These advantages significantly enhance their clinical applicability, and render them excellent alternatives to antibody-based probes in cancer diagnostics and therapeutics. Aptamer probes based on fluorescence, colorimetry, magnetism, electrochemistry, and in conjunction with nanomaterials (e.g., nanoparticles, quantum dots, single-walled carbon nanotubes, and magnetic nanoparticles) have provided novel ultrasensitive cancer diagnostic strategies and assays. Furthermore, promising aptamer targeted-multimodal tumor imaging probes have been recently developed in conjunction with fluorescence, positron emission tomography (PET), single-photon emission computed tomography (SPECT), and magnetic resonance imaging (MRI). The capabilities of the aptamer-based platforms described herein underscore the great potential they hold for the future of cancer detection. In this review, we highlight the most prominent recent developments in this rapidly advancing field.

G-quadruplex-based aptamers against protein targets in therapy and diagnostics

“…This structural complexity results in a high probability of selecting an aptamer that can strongly and specifically interact with the target of interest through hydrogen bonds, salt bridges, van der Waals, hydrophobic and/or electrostatic interactions. The high affinity and selectivity for the target, as well as the multiplicity of possible target types, make aptamers a valid alternative to antibodies in a wide variety of applications, from therapeutics (as drugs or drug-delivery systems) to diagnostic and sensing devices [8][9][10][11][12][13][14][15]. Nucleic acid aptamers exhibit significant advantages over antibodies, such as smaller size, lower immunogenicity, remarkable stability in a wide range of pH (≈4-9) and temperature; in addition, aptamers the chemical and enzymatic stability of aptamers, but can also contribute to greatly broaden their chemical diversity, improving their binding affinity and specificity for a selected target.…”

Self‐Assembled Aptamer‐Nanomedicine for Targeted Chemotherapy and Gene Therapy

“…Similarly to protein antibodies, aptamers bind to their cognate targets via conformational recognition and thus, are often referred to as “chemical antibodies.” As small‐sized oligonucleotide biomaterials, aptamers can be rapidly synthesized and easily conjugated to various functional agents for different clinical needs . The aforementioned features provide aptamers with notable advantages over protein antibodies as targeting ligands to formulate nanoparticles and nanomedicines …”

“…[15][16][17] The aforementioned features provide aptamers with notable advantages over protein antibodies as targeting ligands to formulate nanoparticles and nanomedicines. [18][19][20][21] Anaplastic large cell lymphoma (ALCL) is the most common T-cell lymphoma in children. Biologically, lymphoma cells express high-levels of the surface CD30 receptor, a signaling molecule regulating cell fate and a distinct biomarker for ALCL diagnosis.…”

Aptamer-conjugated PEGylated quantum dots targeting epidermal growth factor receptor variant III for fluorescence imaging of glioma

“…[30][31][32] In recent years, aptamers have been developed as a novel recognition probes constituted with uniquely folded short RNA or ssDNA oligonucleotides which can bind to the targets with high specificity and affinity. 33 In addition, compared with antibodies or polypeptides, aptamers have many advantages including lower immunogenicity, thermal stability, ease of modification, higher specificity, smaller size, lower production cost, and no toxicity. 34,35 Compared with RNA aptamers, DNA aptamers are more stable and cheaper to synthesize.…”