Chlorhexidine digluconate on chitosan-magnetic iron oxide nanoparticles modified electrode: Electroanalysis and mechanistic insights by computational simulations

Sousa, Camila P.; Oliveira, Raissa C. de; Freire, Tiago M.; Fechine, Pierre Basílio Almeida; Salvador, Michele Aparecida; Homem-de-Mello, Paula; Morais, Simone; Lima‐Neto, Pedro de; Correia, Adriana N.

doi:10.1016/j.snb.2016.08.181

Cited by 26 publications

(14 citation statements)

References 35 publications

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“…The results are in agreement with those accomplished by CV (Fig. 1a) [47,57]. Figure 2a, b shows the TEM micrographs for the magnetic nanocomposite at different magnifications.…”

Section: Characterization Of the Modified Electrodesupporting

confidence: 89%

Chitosan-magnetite nanocomposite as a sensing platform to bendiocarb determination

et al. 2018

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A novel platform for carbamate-based pesticide quantification using a chitosan/magnetic iron oxide (Chit-FeO) nanocomposite as a glassy carbon electrode (GCE) modifier is shown for an analytical methodology for determination of bendiocarb (BND). The BND oxidation signal using GCE/Chit-FeO compared with bare GCE was catalyzed, showing a 37.5% of current increase with the peak potential towards less positive values, showing method's increased sensitivity and selectivity. Using square-wave voltammetry (SWV), calibration curves for BND determination were obtained (n = 3), and calculated detection and quantification limits values were 2.09 × 10 mol L (466.99 ppb) and 6.97 × 10 mol L (1555.91 ppb), respectively. The proposed electroanalytical methodology was successfully applied for BND quantification in natural raw waters without any sample pretreatment, proving that the GCE/Chit-FeO modified electrode showed great potential for BND determination in complex samples. ᅟ Graphical abstract.

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“…The results are in agreement with those accomplished by CV (Fig. 1a) [47,57]. Figure 2a, b shows the TEM micrographs for the magnetic nanocomposite at different magnifications.…”

Section: Characterization Of the Modified Electrodesupporting

confidence: 89%

Chitosan-magnetite nanocomposite as a sensing platform to bendiocarb determination

et al. 2018

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“…Iron oxide nanoparticles (IONP) have been used independently or in combination with other materials (nanomaterials, polymers, proteins, etc.) , for the construction of (bio)sensors, presenting improved responses, excellent electrocatalytic activity, and high sensitivity in the detection of analytes in the health, environment and agriculture fields. In particular, the combination with MWCNT has been shown to bring additional electrocatalytic advantages and enhanced performance, besides offering simplicity of construction and low cost .…”

Section: Introductionmentioning

confidence: 99%

Iron Oxide Nanoparticle and Multiwalled Carbon Nanotube Modified Glassy Carbon Electrodes. Application to Levodopa Detection

2018

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The combination of iron (III) oxide nanoparticles (Fe2O3NP) with functionalized multi‐walled carbon nanotubes (MWCNT) has been used to develop a new and easily prepared modified glassy carbon electrode (GCE). The Fe2O3NP‐MWCNT/GCE were electrochemically characterized by cyclic voltammetry with the model hexacyanoferrate(III)/(II) redox probe. Their application as electrochemical sensors was demonstrated using levodopa oxidation, with excellent analytical performance. The analytical parameters compare favourably with other similar modified electrodes reported in the literature. Excellent selectivity was shown in interference studies and the determination of levodopa was carried out in pharmaceutical samples.

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“…From empirical pKa calculations (Blackburn et al, 2007) and by using the pKa predictor of the MarvinSketch software (ChemAxon, 2015), the protonation form at acidic conditions may vary from two to four nitrogen atoms protonated, and consequently net total charge equals to + 2 or +4. At pH = 4, the condition our previous experiments (Sousa et al, 2017) have used, we have analyzed the system with net charges +2 and +4. monoprotonated CHD, while Ha's initial structure is neutral.…”

Section: (C) and (D))mentioning

confidence: 99%

“…Taking these apparently conflicting experimental results into account, in this work we aim to shed light on the oxidation process of chlorhexidine, starting from different neutral forms, and by considering various protonation sites. In a previous work (Sousa et al, 2017) we performed quantum mechanical calculations simulations and free energy studies to support electrochemical studies on CHD oxidation, focusing on the adsorption process. Here, we extend that study in order to give a molecular insight about the effects of the protonation states on degradation pathway of CHD.…”

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Evaluation of degradation mechanism of chlorhexidine by means of Density Functional Theory calculations

Salvador

Sousa

Morais

et al. 2017

Computational Biology and Chemistry

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Chlorhexidine (CHD), a germicidal drug, has degradation products that can be hemotoxic and carcinogenic. However, there is no consensus in literature about the degradation pathway. In order to shed light on that mechanism, we have employed Density Functional Theory to study reactants, in different protonation states, products and intermediates involved in the different pathways. Based on free energy values comparison and frontier molecular orbital analysis, we have obtained the most stable structures in each protonation state. CHD in saturated form has HOMO localized in one p-chloroaniline, and, due to molecule's symmetry, HOMO-1 has contributions from the other side of the molecule, but mainly from the biguanide portion of the molecule, instead of from the p-chloroaniline. For the saturated form, we have studied two possible degradation pathways, starting from the monoprotonated structure, and three pathways starting from the neutral structure. We found out that the mechanisms proposed in literature, whose pathways lead to p-chloroaniline (PCA) formation in a smaller number of steps, are more likely than the mechanisms with more intermediate steps or pathways that do not predict PCA formation. Also, based on free energy results, we have found that the formation of another sub-product (PBG-AU) is favorable as well.

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Chlorhexidine digluconate on chitosan-magnetic iron oxide nanoparticles modified electrode: Electroanalysis and mechanistic insights by computational simulations

Cited by 26 publications

References 35 publications

Chitosan-magnetite nanocomposite as a sensing platform to bendiocarb determination

Chitosan-magnetite nanocomposite as a sensing platform to bendiocarb determination

Iron Oxide Nanoparticle and Multiwalled Carbon Nanotube Modified Glassy Carbon Electrodes. Application to Levodopa Detection

Evaluation of degradation mechanism of chlorhexidine by means of Density Functional Theory calculations

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