Electrochemical Aptasensors Based on Hybrid Metal-Organic Frameworks

Abstract

Metal-organic frameworks (MOFs) offer a unique variety of properties and morphology of the structure that make it possible to extend the performance of existing and design new electrochemical biosensors. High porosity, variable size and morphology, compatibility with common components of electrochemical sensors, and easy combination with bioreceptors make MOFs very attractive for application in the assembly of electrochemical aptasensors. In this review, the progress in the synthesis and application of the MOFs in electrochemical aptasensors are considered with an emphasis on the role of the MOF materials in aptamer immobilization and signal generation. The literature information of the use of MOFs in electrochemical aptasensors is classified in accordance with the nature and role of MOFs and a signal mode. In conclusion, future trends in the application of MOFs in electrochemical aptasensors are briefly discussed.

Keywords: 3-D networks; aptasensor; electrochemical biosensor; metal-organic frameworks; reticular materials.

Figure 1

Chemical structures of the linkers applied for assembling the MOF materials.

Figure 2

Schematic outline of various MOF structures. For a description, see the text above.

Figure 3

Characterization of the Ce-based MOF for the assembly of aptamer for ATP determination. (A) Coordination environments of Ce³⁺ ions and 2-aminoterephtalic acid; (B) the 3-D topological structure; (C) SEM image; (D) EDX elemental mapping [88].

Figure 4

Analysis of the bibliography devoted to the application of aptamers in electrochemical sensors and biosensors performed with the Web of Science database. (A) ‘MOF’ and ‘electrochemical’ search; (B) ‘MOF’ and ‘aptasensor’ search; (C) ‘MOF’ and ‘electrochemical aptasensor’ search; (D) pie chart describing distribution of the signal measurement modes: 1—assessment of permeability of the surface layer; 2—application of biochemical amplification approaches; 3—sandwich assay; 4—measurement of intrinsic redox activity of the MOFs; 5—application of diffusionally free redox indicators.

Figure 5

Covalent attachment of aminated aptamer to an insoluble carrier or electrode.

Figure 6

Biotinylated aptamer synthesis.

Figure 7

Immobilization of aptamer molecules via hybridization with auxiliary DNA strand and the following interaction with an analyte releasing the aptamer from the surface layer.

Figure 8

Monitoring aptamer–analyte interactions by the permeability of the surface layer toward small ions. (A) Mechanism of interaction; (B) changes in the signals recorded with DPV and EIS.

Figure 9

Detection of aptamer–analyte interaction with sandwich analysis using redox-active label.

Figure 10

(A) Displacement protocol for determination of phosphoprotein 1 with methylene blue-labeled aptamer; (B) Determination of E. coli with pinhole aptamer saturated with methylene blue; (C) Changes in the DPV signal of methylene blue corresponded to the analyte binding.