Long-term stable poly(ionic liquid)/MWCNTs inks enable enhanced surface modification for electrooxidative detection and quantification of dsDNA

Abstract

This work demonstrates the use of imidazolium-based poly(ionic liquid)s (PILs) as efficient dispersants of multi-walled carbon nanotubes (MWCNTs). With these polymeric dispersants, highly stable fine dispersions of MWCNTs (inks) can be easily prepared in aqueous media and applied for rather simple but efficient surface modification of screen-printed electrodes (SPEs). Such a modification of SPEs remarkably increases the electroactive surface area and accelerates the electron transfer rate due to synergistic combination of specific features of MWCNTs such as strong adsorptive property and high specific surface with the advantages of PILs like ion conductivity and dispersability. We further show that the PIL/MWCNT-modified SPEs can be beneficially utilized for direct electrochemical analysis of double stranded DNA (dsDNA). Specifically, it is exemplified by the direct electrooxidation of guanine and adenine bases in salmon testes dsDNA chosen as a model system. The linear ranges for the determination of dsDNA correspond to 5-500 µg/mL for the oxidative peak of guanine and 0.5-50 µg/mL for the oxidative peak of adenine. This makes direct electrochemical dsDNA detection with the use of the easy-preparable PIL/MWCNT-modified SPEs strongly competing to currently applied spectral and fluorescent techniques. Furthermore, we show that the developed constructs are capable of sensing a single point mutation in the 12-bases single-stranded DNA fragments. Such detection is of high clinical significance in choosing an adequate anticancer treatment, where the electrochemical identification of the point mutation could offer time and cost benefits.

Nanoconfined Crosslinked Poly(ionic liquid)s with Unprecedented Selective Swelling Properties Obtained by Alkylation in Nanophase-Separated Poly(1-vinylimidazole)-l-poly(tetrahydrofuran) Conetworks

“…Another class of imidazole-based polymers belongs to poly(ionic liquid)s (PILs), that is macromolecules with ionic liquid (IL) moieties. Due to the challenging tasks of the synthesis, revealing the structure–property relationships, and the broad range of special application possibilities, PILs have been intensively investigated in recent years (see e.g., references [ 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 ] and references therein). PILs may find applications in energy production as proton [ 57 ], electron [ 58 , 59 ], or Li-ion [ 60 , 73 ] conducting materials; as metal free [ 61 ] and metal containing [ 62 ] catalysts; gas separation membranes [ 63 , 64 ]; DNA isolation microspheres [ 65 ] etc.…”

“…PILs may find applications in energy production as proton [ 57 ], electron [ 58 , 59 ], or Li-ion [ 60 , 73 ] conducting materials; as metal free [ 61 ] and metal containing [ 62 ] catalysts; gas separation membranes [ 63 , 64 ]; DNA isolation microspheres [ 65 ] etc. PILs are prepared either by polymerization of ionic liquid-type monomers [ 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 ], or less frequently by polymer analogous postmodification of suitable polymers [ 66 , 67 , 68 ] as shown, for instance, recently by the synthesis of PVIm-based PIL brushes via termination of oxazoline polymerization by PVIm homopolymer [ 68 ]. Although several applications require crosslinked PILs, PIL networks have not gained broad interest yet.…”

Rational Design of Amphiphilic Diblock Copolymer/MWCNT Surface Modifiers and Their Application for Direct Electrochemical Sensing of DNA

“…It is worth noting that lower amounts of A and G residues are accessible for electrooxidation in the long rigid double-stranded DNA (dsDNA) than in short oligodinucleotides, flexible single-stranded DNA (ssDNA), or individual heterocyclic bases. Hence, an electrochemical signal coming from dsDNA is weaker [ 21 ], lowering the sensitivity of analysis [ 10 , 11 , 22 , 23 ].…”

“…However, MWCNTs are hardly dispersible in most conventional solvents, and that makes them not easy-to-handle. The main strategy to overcome this disadvantage is dispersing of MWCNTs in solutions of synthetic or natural polymers [ 23 , 30 , 31 , 32 , 33 , 34 ].…”

“…Due to their amphiphilic structure, such materials are good dispersants for carbon nanomaterials. Moreover, the charged groups provide the subsequent immobilization of analytes, while the presence of a hydrophobic segment preferably with a low or moderate glass transition temperature T g might considerably facilitate the modification of hydrophobic carbon surfaces [ 23 , 34 , 35 , 36 ].…”