Hybrid Nanocomposite Platform, Based on Carbon Nanotubes and Poly(Methylene Blue) Redox Polymer Synthesized in Ethaline Deep Eutectic Solvent for Electrochemical Determination of 5-Aminosalicylic Acid

Abstract

A novel hybrid composite of conductive poly(methylene blue) (PMB) and carbon nanotubes (CNT) was prepared for the detection of 5-aminosalicylic acid (5-ASA). Electrosynthesis of PMB with glassy carbon electrode (GCE) or with carbon nanotube modified GCE was done in ethaline deep eutectic solvent of choline chloride mixed with ethylene glycol and a 10% v/v aqueous solution. Different sensor architectures were evaluated in a broad range of pH values in a Britton-Robinson (BR) buffer using electrochemical techniques, chronoamperometry (CA), and differential pulse voltammetry (DPV), to determine the optimum sensor configuration for 5-ASA sensing. Under optimal conditions, the best analytical performance was obtained with CNT/PMBDES/GCE in 0.04 M BR buffer pH 7.0 in the range 5–100 µM 5-ASA using the DPV method, with an excellent sensitivity of 9.84 μA cm−2 μM−1 (4.9 % RSD, n = 5) and a detection limit (LOD) (3σ/slope) of 7.7 nM, outclassing most similar sensors found in the literature. The sensitivity of the same sensor obtained in CA (1.33 μA cm−2 μM−1) under optimal conditions (pH 7.0, Eapp = +0.40 V) was lower than that obtained by DPV. Simultaneous detection of 5-ASA and its analogue, acetaminophen (APAP), was successfully realized, showing a catalytic effect towards the electro-oxidation of both analytes, lowering their oxidation overpotential, and enhancing the oxidation peak currents and peak-to-peak separation as compared with the unmodified electrode. The proposed method is simple, sensitive, easy to apply, and economical for routine analysis.

Electroanalytical Overview: The Sensing of Mesalamine (5-Aminosalicylic Acid)

“…37 Other work has reported the use of a GCE composite composed of the electroactive redox polymer formed in a ternary deep eutectic solvents using gold nanoparticles 38 or with carbon nanotubes. 39 In the former case, they performed the simultaneous sensing of ascorbic acid and 5-ASA while in the latter, simultaneously acetaminophen and 5-ASA, both approaches showing low detection limits which are successful for determining 5-ASA within pharmaceuticals. Deep eutectic solvents are attracting attention since they are composed of at least one hydrogen bond donor and a hydrogen bond acceptor.…”

“…Clearly, further research needs to measure both 5-ASA and N-acetyled-5-ASA via electroanalytical approaches. Furthermore, no one has yet used electroanalytical sensing in real measurements, i.e., collecting plasma from volunteers after a single-dose oral administration of 5-ASA in order to measure both 5-ASA and N-acetyled-5-ASA and evaluate the pharmacokinetics, pharmacodynamics, and efficacy of the drug39 �further work needs to address this.…”

Application of a novel deep eutectic solvent modified carbon nanotube for pipette-tip micro solid phase extraction of 6-mercaptopurine

“…They have distinctive features such as a low toxicity and cost of preparation, low flammability, biodegradability, and can be prepared with a wide range of polarities, which make them suitable for any extraction processes, including drugs [ 18 ]. For preconcentration of some of drugs, CNTs and poly (methylene blue) redox polymer prepared in ethaline DES [ 19 ], DES loaded onto graphene oxide [ 20 ], and DES stir bar sorptive extraction [ 21 ] were already used which showed excellent results. However, no report we could find on using a CNT coated with a hydrophobic DES for drug extraction.…”

Electrochemical Quantification of Dopamine in Presence of Ascorbic Acid with a Glass Carbon Electrode Modified with Poly5aphen Polymerized from a Deep Eutectic Solvent

“…It has been found that Deep Eutectic Solvents or DES, for the initials in English (Deep Eutectic Solvent), exhibit a great potential option for PC electrosynthesis, due to their relative low wide potential windows, chemical stability, ease of preparation, low cost, and biodegradability compared to conventional aqueous and organic solvents (4,5). Furthermore, the synthesis of polymers on DES can lead to formation of films in which DES components are capable of modulating nucleation and growth mechanisms through charge neutralization and changes in oxidation/reduction potentials, promoting cell growth, that is growth in optimizable systems of nanoscale size (6).…”