unsaturated π-bonds in their structure lead to a high electrical conductivity of CNMs.
Enabling and enhancing the electron transfer process between an electrode and a
given molecule is the principle of such applications of CNMs. It is considered that
the enhancement in properties of CNMs toward electrochemical detection of the
molecules can be achieved via incorporation of cyclodextrin units into the material.
The CDs promote the supramolecular recognition of various molecules. Hence, the
considered reason of improved performance of the CD-bearing CNM sensors is the
synergistic effect between the adsorption of the detected molecules on the surface of
the CNMs and the formation of the inclusion complexes with CDs.
Electrochemical sensing that uses conjugates of CNMs with CDs constitutes an
emerging and widely explored area of molecular recognition research. Graphene
oxide is a material characterized by a single graphene sheet, or “monolayer,” that
displays unique electronic and mechanical properties that are advantageous for
sensing applications. Fabrications of the sensors based on CD-modified two-dimensional GO or rGO covered both covalent and non-covalent approaches. From the
synthetic point of view, the presence of oxygen groups on the surface of GO or rGO
opens avenues for an enhanced hydrogen-bonding-dependent self-assembly phenomenon with the inclusion of CD units, as well as for covalent functionalization
via, e.g., amide or ester bond formation. More works referred to the experimental
procedure reported by Guo et al. (Fig. 2) [8] suggested the formation of the noncovalent β-CD/rGO material via the hydrogen-bonding-dependent adsorption of
CDs on the surface of rGOs. Application of non-covalent CD/GO and CD/rGO
materials as versatile electrochemical sensors can be clearly claimed, because these
constructs were used for the detection of various molecules. Bioactive species [8, 9],
drugs [8, 9], and organic pollutants [10, 11] were detected with excellent LOD
values. Also the three-dimensional rGO as the bearing material has been used to
conjugate with CD for fabricating an electrochemical sensor [9, 12].
Meanwhile, carbon nanotubes, with unique tubular shape, possess encouraging
electronic properties, such as good electrical conductivity and broad electrochemical
potential window, and MWCNTs perform more excellent electronic properties in
comparison to SWCNTs. CD/MWCNT sensors were successfully applied for the
electrochemical determination of organic pollutants [13] and various biomolecules
[14, 15]. Recently, construction of the hybrid carbon platforms composed of more
than one graphene nanostructure, as cyclodextrin-bearing materials for electrochemical
sensing, was also studied. Second carbon material [16], metallic nanoparticles [17] and
metal oxide nanoparticles [18] have been introduced to the carbon platform for electrochemical sensing. Introduction of the second carbon material to a carbon platform was
found to increase the number of CD units in the nanostructure, because of enhancing
hydrogen-bonding interactions. And the hybrid with metallic nanoparticles and metal
oxide nanoparticles improved the electrical conductivity and catalytic performance of
CD-conjugated CNMs electrochemical sensor.
Due to the CD cavity’s unique hydrophobic character and inherent chirality,
electrochemical sensing of CD-conjugated carbon nanomaterials for chiral recognition
has been widely investigated [12, 19–23]. The cyclodextrin-conjugated graphene
quantum dots β-CD/GQDs have been applied for the electrochemical detection of
428
W. Liang and S. Shuang
Enabling and enhancing the electron transfer process between an electrode and a
given molecule is the principle of such applications of CNMs. It is considered that
the enhancement in properties of CNMs toward electrochemical detection of the
molecules can be achieved via incorporation of cyclodextrin units into the material.
The CDs promote the supramolecular recognition of various molecules. Hence, the
considered reason of improved performance of the CD-bearing CNM sensors is the
synergistic effect between the adsorption of the detected molecules on the surface of
the CNMs and the formation of the inclusion complexes with CDs.
Electrochemical sensing that uses conjugates of CNMs with CDs constitutes an
emerging and widely explored area of molecular recognition research. Graphene
oxide is a material characterized by a single graphene sheet, or “monolayer,” that
displays unique electronic and mechanical properties that are advantageous for
sensing applications. Fabrications of the sensors based on CD-modified two-dimensional GO or rGO covered both covalent and non-covalent approaches. From the
synthetic point of view, the presence of oxygen groups on the surface of GO or rGO
opens avenues for an enhanced hydrogen-bonding-dependent self-assembly phenomenon with the inclusion of CD units, as well as for covalent functionalization
via, e.g., amide or ester bond formation. More works referred to the experimental
procedure reported by Guo et al. (Fig. 2) [8] suggested the formation of the noncovalent β-CD/rGO material via the hydrogen-bonding-dependent adsorption of
CDs on the surface of rGOs. Application of non-covalent CD/GO and CD/rGO
materials as versatile electrochemical sensors can be clearly claimed, because these
constructs were used for the detection of various molecules. Bioactive species [8, 9],
drugs [8, 9], and organic pollutants [10, 11] were detected with excellent LOD
values. Also the three-dimensional rGO as the bearing material has been used to
conjugate with CD for fabricating an electrochemical sensor [9, 12].
Meanwhile, carbon nanotubes, with unique tubular shape, possess encouraging
electronic properties, such as good electrical conductivity and broad electrochemical
potential window, and MWCNTs perform more excellent electronic properties in
comparison to SWCNTs. CD/MWCNT sensors were successfully applied for the
electrochemical determination of organic pollutants [13] and various biomolecules
[14, 15]. Recently, construction of the hybrid carbon platforms composed of more
than one graphene nanostructure, as cyclodextrin-bearing materials for electrochemical
sensing, was also studied. Second carbon material [16], metallic nanoparticles [17] and
metal oxide nanoparticles [18] have been introduced to the carbon platform for electrochemical sensing. Introduction of the second carbon material to a carbon platform was
found to increase the number of CD units in the nanostructure, because of enhancing
hydrogen-bonding interactions. And the hybrid with metallic nanoparticles and metal
oxide nanoparticles improved the electrical conductivity and catalytic performance of
CD-conjugated CNMs electrochemical sensor.
Due to the CD cavity’s unique hydrophobic character and inherent chirality,
electrochemical sensing of CD-conjugated carbon nanomaterials for chiral recognition
has been widely investigated [12, 19–23]. The cyclodextrin-conjugated graphene
quantum dots β-CD/GQDs have been applied for the electrochemical detection of
428
W. Liang and S. Shuang