ABSTRACT
Ivabradine hydrochloride (IVR) is a medically important drug because of its ability to lower the heart rate. Techniques reported for IVR determination were expensive, laborious, besides being of poor selectivity. In this study, iron oxide @ carbon nanotube (Fe2O3@MWCNTs) nanocomposite and molecularly imprinted polymer (MIP) were synthesized and used in the fabrication of carbon paste electrodes (CPEs) for the potentiometric detection of IVR in biological and pharmaceutical samples. CPEs of the best sensor were formulated from graphite (41 wt%) as a carbon source, MIP (3 wt.%) as an ionophore, Fe2O3@MWCNTs (5 wt%) as a modifier, and nitrophenyl octyl ether (NPOE, 51 wt.%) as a conductive oil so-called plasticizer. The best sensor exhibits a Nernstian slope (response) of 56 mV decade-1 within the IVR concentration range from 1.0 × 10-3 M to 9.8 × 10-8 M with high selectivity against interfering species (ascorbic, maltose, glucose, lactose, dopamine, glycine) over those reported earlier. The use of Fe2O3@MWCNTs together with MIP in the electrode formulation was found to improve the limit of detection (LOD) from 630 to 98 nM along with high reversibility, a short response time of 30 s, and a good lifetime of more than 2 weeks. The sandwich membrane (SMM) method was used to quantify the H-bonding complexing strength of the MIP binding sites for IVR with Log ß ILn = 11.33. The constructed sensors were successfully applied for the IVR determination in blood serum, urine, and commercial formulations (Savapran®) with high sensitivity.
ABSTRACT
Ivabradine hydrochloride (IVB) has shown high medical importance as it is a medication for lowering the heart rate for the symptomatic chronic heart failure and symptomatic management of stable angina pectoralis. The high dose of IVB may cause severe and prolonged bradycardia, uncontrolled blood pressure, headache, and blurred vision. In this study, a highly sensitive carbon-paste electrode (CPEs) was constructed for the potentiometric determination of IVB in pharmaceutical formulations. t-Butyl calixarene (t-BCX) was used as an ionophore due to its ability to mask IVB in the cavity via multiple H-bonding at the lower rim, as estimated quantitatively by the sandwich membrane method (Log ßILn = 8.62). Besides, the use of multi-walled carbon nanotubes decorated with Fe2O3 nanoparticles (Fe2O3@MWCNTs) as an additive for the paste electrode significantly improved the detection limit of the sensor up to 36 nM, with Nernstian response of 58.9 mV decade-1 in the IVB linear dynamic range of 10-3-10-7 M in aqueous solutions. The constructed sensors showed high selectivity against interfering species that may exist in physiological fluids or pharmaceutical formulations (e.g. Na+, K+, NH4+, Ca2+, Mg2+, Ba2+, Fe3+, Co2+, Cr3+, Sr2+, glucose, lactose, maltose, glycine, dopamine, and ascorbic acid). The sensors were successfully employed for IVB determination in the pharmaceutical formulations (Savapran®).
Subject(s)
Calixarenes , Nanotubes, Carbon , Drug Compounding , Electrodes , Ivabradine , PotentiometryABSTRACT
In this work, we investigated the parameters for decorating multiwalled carbon nanotubes with iron oxide nanoparticles using a new, inexpensive approach based on wet chemistry. The effect of process parameters such as the solvent used, the amount of iron salt or the calcination time on the morphology, decoration density and nanocluster size were studied. With the proposed approach, the decoration density can be adjusted by selecting the appropriate ratio of carbon nanotubes/iron salt, while nanoparticle size can be modulated by controlling the calcination period. Pristine and iron-decorated carbon nanotubes were deposited on silicon substrates to investigate their gas sensing properties. It was found that loading with iron oxide nanoparticles substantially ameliorated the response towards nitrogen dioxide.
