Solid-contact potentiometric aptasensor based on aptamer functionalized carbon nanotubes for the direct determination of proteins

Abstract

A facile, solid-contact selective potentiometric aptasensor exploiting a network of single-walled carbon nanotubes (SWCNT) acting as a transducing element is described in this work. The molecular properties of the SWCNT surface have been modified by covalently linking aptamers as biorecognition elements to the carboxylic groups of the SWCNT walls. As a model system to demonstrate the generic application of the approach, a 15-mer thrombin aptamer interacts with thrombin and the affinity interaction gives rise to a direct potentiometric signal that can be easily recorded within 15 s. The dynamic linear range, with a sensitivity of 8.0 mV/log a(Thr) corresponds to the 10(-7)-10(-6) M range of thrombin concentrations, with a limit of detection of 80 nM. The aptasensor displays selectivity against elastase and bovine serum albumin and is easily regenerated by immersion in 2 M NaCl. The aptasensor demonstrates the capacity of direct detection of the recognition event avoiding the use of labels, mediators, or the addition of further reagents or analyte accumulation.

Protein Detection with Potentiometric Aptasensors: A Comparative Study between Polyaniline and Single-Walled Carbon Nanotubes Transducers

“…Further investigation is needed to determine the correct formation of the aptamers to thoroughly understand the underlying phenomena of the generated EMF. In comparison to the previously reported CNT-based potentiometric sensor [16], PANI-based sensor does provide neither good sensitivity nor stability. However, both sensors responded to interfering proteins exhibiting a similar selective behavior.…”

“…The area differences between PANI and SWCNTs sensors could result from the fact that the surface area to volume ratio of SWCNTs is much higher than that of the PANI chains deposited in the two-dimensional plane of the sensor surface. Furthermore, spaghetti-like formation [16] of the SWCNTs compared to very orderly distributed PANI chains also supports this result. The total charges on the surface are calculated as 5.63 × 10 −6  C for PANI- and 8.21 × 10 −5  C for SWCNT-based sensors with standard deviations of 1.08 × 10 −06  C and 1.29 × 10 −05  C for PANI and SWCNTs, respectively ( N = 3).…”

“…Düzgün et al recently demonstrated the feasibility to potentiometrically detect large analytes such as proteins using a nanostructured hybrid material (based on carbon nanotubes, CNTs) that incorporates thrombin binding aptamers (TBAs) [16]. The main advantages of this detection system are simplicity due to the two-electrode system used in potentiometry, low cost, and real-time detection which make it highly valuable for different types of applications.…”

Review of progresses on clinical applications of ion selective electrodes for electrolytic ion tests: from conventional ISEs to graphene-based ISEs

“…[14] hamid Reza Rajabi et al [15] has reported a voltammetric sensor for selective recognition and sensitive determination of mercury ions using glassy carbon (GC) electrode modified with an ion imprinted polymeric nanobeads and multi-wall carbon nanotubes. And, the designed modified electrode showed a linear response in the range of 1.0 × 10 −8 to 7.0 × 10 −4 mol/L of hg 2+ ion with a detection limit of 5.0 × 10 −9 mol/L.…”

Aptamer in Bioanalytical Applications

“…Furthermore, thrombin detection was also achieved using a solid-contact potentiometric aptasensor prepared by modifying the single-walled carbon nanotube surface with thrombin aptamer. 76 …”