Functionalization of MWCNTs with Ferrocene‐poly(p‐phenylene) and Effect on Electrochemical Properties: Application as a Sensing Platform

Abstract

1Introduction Nanostructures such as carbon nanotubes (CNTs) have been extensively used as transducers for electrochemical biosensing analysis [1].T hese nanomaterials offer al arge surface-to-volumer atio and exhibit excellent chemical and thermal stability [2].M oreover, they have electronic properties leading to the enhancement of electron transport. Thus,m ulti-walled carbon nanotubes (MWCNTs) are appropriate nanomaterials for covalent binding of redox proteins and mediators [3].O ne of the challenges with employing CNTsi nab iosensor device is the individual dispersion of nanotubes and the introduction of functional groups such as redox mediators.C NTs are insoluble in aqueous and polar media and have at endency to form agglomerates due to hydrophobic interactions and Va nder Waals forces between nanotubes.Different approaches have been employed for their dispersion in the solution [ 4,5].T he most common method to disperse carbon nanotubesi nt he solution is to modify them chemically.Amajor strategyc onsists in the oxidation of carbon nanotubes by the oxygen of the air in concentrated sulfurica cid, nitric acid, aqueous hydrogenp eroxide,o rt he mixture of acids [6].D uring these reactions variousc hemicalg roupsa re formed on CNTs surface such as carboxylic, ketones,e sters,a ldehydes,a lcohol groups [7-9].T he polar carboxylic groups protect carbon nanotubes from aggregation and allow high dispersion in aqueous medium or organic solvents.T he functionalization of carbon nanotubes is facilitatedb ym any defects at the end caps of CNTs [10].E nd capsh ave at endency to be composed of highlyc urved fullerene like hemispheres, which are also highly-reactive as compared to the sidewalls.S uch drastic conditionsa sa cid oxidation and sonication leads to thef ormation of functional groups at the end capso fC NTs,b yo pening the tube caps as well as the formation of holesi nt he sidewalls.T he efficiency of functionalization depends also on the size of carbon nanotubes (the reactivity of CNTs increase with as mall nanotubed iameter) and their chirality [11].A dditionally, oxidative conditions have al arge influence on the electronic properties of the carbon nanotubes with ad ecrease in their conductivity.N on-covalent functionalizationo f nanotubes is of particular interestb ecause it does not include the physical properties of CNTs[ 12],b ut improves the solubility and the process ability.T his type of functionalization mainly involves surfactants,c hargedm acromolecules and polymers,a romatic compounds.I tc onsists of Va nd er Waals,e lectrostatic interactions, and p-stacking. Thel etterc an be obtainedb yt heir interaction with organic compounds such as methalloporphyrins [13] or Abstract:M WCNTsh ave been dispersed with modified ferrocene-poly(para-phenylene) by p staking interaction to improve dispersion of MWCNTS in organic solution. Such interaction has been demonstrated through electrochemical and chemical characterizationo ft he composite. Al ayer based on the formed composite (MWCNTs/Fc-PPP) has been de...

A Facile Electrochemical Sensor Labeled by Ferrocenoyl Cysteine Conjugate for the Detection of Nitrite in Pickle Juice

“…It should be mentioned that the rapid growth of organometallic chemistry has benefitted from the discovery of ferrocene and its derivatives [20]. The most important application of ferrocene and its derivatives is that they can be used as electrochemical probes for detection of a wide range of biomolecules with great stability in aqueous media.…”