Abstract
Nanomaterials have become one of the most interesting sensing materials because of their unique size- and shape-dependent optical properties, high surface energy and surface-to-volume ratio, and tunable surface properties. Aptamers are oligonucleotides that can bind their target ligands with high affinity. The use of nanomaterials that are bioconjugated with aptamers for selective and sensitive detection of analytes such as small molecules, metal ions, proteins, and cells has been demonstrated. This review focuses on recent progress in the development of biosensors by integrating functional aptamers with different types of nanomaterials, including quantum dots, magnetic nanoparticles (NPs), metallic NPs, and carbon nanotubes. Colorimetry, fluorescence, electrochemistry, surface plasmon resonance, surface-enhanced Raman scattering, and magnetic resonance imaging are common detection modes for a broad range of analytes with high sensitivity and selectivity when using aptamer bioconjugated nanomaterials (Apt-NMs). We highlight the important roles that the size and concentration of nanomaterials, the secondary structure and density of aptamers, and the multivalent interactions play in determining the specificity and sensitivity of the nanosensors towards analytes. Advantages and disadvantages of the Apt-NMs for bioapplications are focused.
Highlights
Aptamers (Apt) that are short single-stranded nucleic acids (DNA or RNA) have been used to bind from small solutes to peptide to proteins to cells, viruses, or parasites, with high affinity [1,2,3,4,5,6].These functional nucleic acids can fold into well-defined three-dimensional structures to form binding pockets and clefts for the specific recognition and tight binding of any given molecular target
Aptamer-based homogeneous and heterogeneous sensor systems have been employed for the detection of metal ions, small organic molecules, proteins, and nucleic acids
The change of surface plasmon resonance (SPR) signal resulted in the hybridization reaction between aptamer and Au NPs-tagged complementary ssDNA decreased upon increasing the number of tertiary-structured aptamers, which is linearly proportional to the concentration of adenosine over the range 1 nM to 1 M
Summary
Aptamers (Apt) that are short single-stranded (ss) nucleic acids (DNA or RNA) have been used to bind from small solutes to peptide to proteins to cells, viruses, or parasites, with high affinity [1,2,3,4,5,6]. The equilibrium dissociation constants (Kd) of aptamers to targets are usually in the range of picomolar (pM) to micromolar ( M), similar to those of antibodies for antigens [9,10] Having such high affinity, aptamer-based homogeneous and heterogeneous sensor systems have been employed for the detection of metal ions, small organic molecules, proteins, and nucleic acids. The SPR frequency of Au NPs changes dramatically upon varying the refractive index of the local environment and/or the average distance between Au NPs. Systems based on analyte-induced aggregation of Au NPs have been employed for the colorimetric detection of cells, nucleic acids, proteins, small molecules, and metal ions [27,28,29,30,31]. The functionalized NMs are selective and sensitive for the analytes, showing their great potential in biosensing and bioimaging
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