They can be produced synthetically and commonly identified in vitro from vast combinatorial different libraries that comprise trillions of different sequences by a process known as systematic evolution of ligands by exponential enrichments (SELEX) [7-10], that has recently been fully automated. Automation has reduced in vitro aptamer selection times from months to days. Typically, after 5 to 15 Inhibitors,Modulators,Libraries cycles of the SELEX process, the library is reduced to contain only a small number of aptamers which exhibit particularly high affinity to a target. 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 Inhibitors,Modulators,Libraries for the detection of metal ions, small organic Inhibitors,Modulators,Libraries molecules, proteins, and nucleic acids. Fluorescence, colorimetry, and electrochemistry are common detection modes used in these sensor systems [11-16].The past few years have witnessed progressive advance in the synthesis and characterization of a variety of nanomaterials (NMs), including metallic nanoparticles (NPs), quantum dots (QDs), magnetic NPs, silica (SiO2) NPs, carbon nanotubes (CNTs), and so on [17]. Having large surface area, and unique size, shape and composition-dependent physical and chemical properties including surface plasmon resonance (SPR), surface enhanced Raman scattering (SERS), fluorescence, electrochemistry, magnetism, and/or catalytic activity, those NMs are promising candidates as basic building and signaling elements for fabrication of biosensors with great sensitivity [18-21].
In the past few years, integration of functional aptamers into NMs has become a new interdisciplinary field that aims at providing new hybrid sensing systems (sensors) for specific and sensitive molecular recognition [15,16,21]. This novel integration has yielded various types of sensors for selective and sensitive detection of a wide range of analytes such as adenosine, Inhibitors,Modulators,Libraries cocaine, mercuric ion, and thrombin. Sensors are devices that respond to physical or chemical stimuli and produce detectable signals [22-24]. A sensor requires at least two steps: target recognition and signal transduction [21-24]. The target recognition element can be any chemical or biological entity such as small organic molecules, peptides, proteins, nucleic acids, carbohydrates, or even whole cells.
In these studies aptamers were used as the target recognition elements. Ideally, this element should have high affinity (low detection limit), high specificity (low interference), wide dynamic range, fast response time, and long shelf life. Signal transduction elements are responsible Anacetrapib for converting molecular Ganetespib cancer recognition events into physically detectable signals such as fluorescence, color, electrochemical signals, and magnetic resonance image changes.