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Aptasensors as any biosensor consists of two main components: a bioreceptor and a transducer. In case of aptasensors the bioreceptor is made up of aptamers - short synthetic nucleic acids.

Antamers are very small (5–25 kDa) and exhibit superior specificity and physicochemical stability compared to antibodies (another commonly used transducer). On top of that aptamers have low susceptibility to denaturation, they are low in cost, have less batch variation, and can be easly modified to facilitate covalent bonding to materials surfaces.

Most common substrate employed in a aptasensor is gold (Au). Most frequently used method to immobilize aptamer on this metal surface is via thiol-Au interactions. In orderd to achive that aptamers are first modified with short thiols at the 3' or 5' end. Other methods are: amine-Au interactions or via specific interactions using biotin-streptavidin/avidin/neutravidin.

Transducers
Depending on the method, different transducers are applied.

Optical
Long aptamers undergo conformational change when target sample is introduced. If signaling or reporter molecules are incorporated into the aptamer, then target binding event can be detected. For example fluorescent detection aptasensor was used by Ozaki and colleagues to detect L-argininamide.

Electrochemical
Due to its ease of fabrication and easy integration of electrochemical cells with lab-on-a-chip devices, electrochemical detection is becoming increasingly popular in biosensors. This platform enables simultaneous detection of multiple analytes on a simple, fast, and inexpensive platform. Typically, electrochemical detection setups include three electrodes: the working electrode, auxiliary electrode, and reference electrode. Changes in current or potential resulting from biomolecular interactions are detected at the electrode interface.

Electrochemical detection has been applied in several ways for aptamer sensing. Some of these include inorganic or organic catalysts, enzymes, redox enzymes, and nanoparticles. Aptasensor can also employs electroactive labels such as ferricyanide, ferrocene , methylene blue (MB) , as redox-active reporting units.

Mass-sensitive
Mass-sensitive transucers include, among other: Surface plasmon resonance (SPR), Quartz crystal microbalance (QCM).