Novel supramolecular assemblies of repulsive DNA–anionic porphyrin complexes based on covalently modified multi-walled carbon nanotubes and cyclodextrins

Abstract

A strategy for constructing novel DNA–anionic porphyrin supramolecular assemblies by “fixation” of CNTs and “inclusion” of CDs was reported.

Abnormal Anionic Porphyrin Sensing Effect for HER2 Gene Related DNA Detection via Impedance Difference between MWCNTs and Single-Stranded DNA or Double-Stranded DNA

“…As described in Scheme 1 , MWCNTs can be readily modified by TSPP, which will push DNA away from the surface of CNTs in the meantime [ 37 ]. When increasing the concentration of TSPP solution, due to the increasingly strong electrostatic repulsion, more and more loosely-assembled dsDNA on CNTs surface were substituted by TSPP than tightly-assembled ssDNA [ 20 , 34 , 35 , 36 ], leading to a greater decrease in the impedance value than that caused by ssDNA, and finally leading to a bigger difference in the impedance values between ssDNA and dsDNA. However, after the concentration of TSPP solution was >2.5 × 10 −7 M and with its further increase, more and more TSPP molecules were absorbed by CNTs to add the negative charges of the electrode surface [ 25 ], which prevented the approach of the negative [Fe(CN) 6 ] 3−/4− and blocked the electron transfer channel, instead leading to a gradual decrease in the impedance difference.…”

“…The unique structure of porphyrin (aromatic and planar molecule) allows it to strongly interact with CNTs through π-π conjugation, and porphyrin/CNTs complexes have been widely prepared for various applications in different fields [ 20 , 21 , 22 ]. It is considered that the flattening of porphyrin molecules can reduce the distance between porphyrin planes and aromatic rings-based nanomaterials (including CNTs) [ 23 ], which will cause an efficient acceleration in the electron transfer between porphyrin/nanomaterial complex and the surface of the electrode [ 24 ], exhibiting great promise for applications in the electrochemistry field.…”

“…Then, to enlarge the impedance difference, anionic porphyrin will be utilized due to its “natural” electrostatic repulsion with DNA [ 37 ] and its strong conjugative interaction with CNTs [ 20 ]. So, as shown in Scheme 1 , secondly, an anionic porphyrin, meso-tetra(4-sulfophenyl)-porphyrin (TSPP), is added to the system of E1 or E2 to construct an electrochemical platform of TSPP/ssDNA/MWCNTs/GCE ( E3 ) orTSPP/dsDNA/MWCNTs/GCE ( E4 ), respectively, where TSPP will rival with DNA for the surface of CNTs and cause the decrease of impedance values.…”

“…Thus, based on the abnormal regulating and sensing effect of anionic porphyrin on different DNA/CNTs complexes, this assay presented can hereby establish a new efficient DNA electrochemical sensor for HER2 detection without any label, which will have a broad prospect for cancer diagnosis or treatment. Our previous research on interactions between DNA and anionic porphyrin/MWCNTs complex [ 20 ] will provide high feasibilities for the proposed strategy described in Scheme 1 . At the same time, this current work will surely offer a novel perspective for sensor fabrication via unconventional addition of anionic porphyrin to generate and amplify impedance disparity instead of utilizing optical and chemical sensing amplification, and it also will enrich the research on the unusual composite system containing anionic porphyrin, DNA and CNTs which will combine the advantages of these three kinds of compounds, especially by using the exceptional sensing effect of anionic porphyrin, which will thus will open and pave many potential avenues towards for various applications in electrochemically biomedical fields.…”

Carbon nanomaterials and their application to electrochemical sensors: a review

“…Although various polymers [162][163][164], DNA [165] and detergents [166] have all shown potential as surfactants in this process, to date, sodium dodecyl sulfate (SDS) has been the most widely used [167][168][169][170][171]. SDS has been used to prepare suitable homogeneous dispersions of CNTs for the preparation of thin films at the electrode interface [172,173].…”