Carbon nanotubes-functionalized urchin-like In2S3 nanostructure for sensitive and selective electrochemical sensing of dopamine

A strategy to differentiate dopamine and levodopa based on their cyclization reaction regulated by pH

Levodopa is often used to treat Parkinson's disease. It coexists with dopamine in human fluids and is electrochemically oxidized at the same potential as dopamine. Differentiating levodopa from dopamine is difficult via electrochemical techniques. Taking advantage of the differences in the rate constants of levodopa and dopamine for the intramolecular cyclization reaction, we observed that the cyclization reaction of dopamine-quinone was completely suppressed under pH 4.8, while that of levodopa-quinone occurred. The product of cyclization caused a new cathodic peak at negative potential. Its peak current was dependent on the concentration of levodopa but not that of dopamine. As a result, we developed a method of detecting levodopa in the presence of dopamine with a bare glassy carbon electrode.

Nano assembly of NiFe spheres anchored on f-MWCNT for electrocatalytic reduction and sensing of nitrofurantoin in biological samples

The current study reports a facile simple, low-cost electrochemical sensor in the detection of nitrofurantoin (NFT) by using NiFe/f-MWCNT hybrid composite as a promising electrocatalyst. NFT is an antibiotic drug that is extensively using in pharmaceuticals and also in animal food production which causes a severe threat for both human and animal environments. Extending the residues of NFT are left into rivers, soils, lakes, and groundwaters either found or discharged leading health issues. To this NiFe/f-MWCNT composite was synthesized using a hydrothermal mechanism and then ultrasonicated to form a hybrid composite for catalytic evaluation and electrochemical detection of NFT for the very first time. Furthermore, the physicochemical properties of NiFe nanospheres conjugated on f-MWCNT are scrutinized using various analytical and spectroscopical techniques. Resulting transmission electron microscopy (TEM) displays a chain like NiFe nanospheres anchored on f-MWCNT with a well-defined spherical shape, without any comprehensive agglomeration. The NiFe/f-MWCNT screen printed carbon paste electrode (SPCE) displayed an excellent electrocatalytic activity for NFT with a LOD of 0.03 µM and a sensitivity of 11.45 µA µM^-1 cm^-2. establishing a new selectivity and with the existence of co-interfering compounds. To enhance the practical abilities analysis were performed in Human serum and urine samples which resulted in satisfactory recoveries with high precision and linear accuracy illustrated in Scheme 1.

Synthesis of a manganese dioxide nanorod-anchored graphene oxide composite for highly sensitive electrochemical sensing of dopamine

A novel manganese dioxide nanorod-anchored graphene oxide (MnO₂ NRs/GO) composite was synthesized by a simple hydrothermal method for the development of a highly sensitive electrochemical sensor for dopamine.

Highly selective and sensitive determination of dopamine in biological samples via tuning the particle size of label-free gold nanoparticles

Herein, a rapid, sensitive and selective approach for the colorimetric detection of dopamine (DA) was developed utilizing unmodified gold nanoparticles (AuNPs). This assay relied upon the size-dependent aggregation behavior of DA and three other structurally similar catecholamines (CAs), offering highly specific and accurate detection of DA. By means of this study, we attempted to overcome the tedious procedures of surface premodifications and achieve selectivity through tuning the particle size of AuNPs. DA could induce the aggregation of the AuNPs via hydrogen-bonding interactions, resulting in a color change from pink to blue which can be monitored by spectrophotometry or even the naked-eye. The proposed colorimetric probe works over the 0.1 to 4μM DA concentration range, with a lower detection limit (LOD) of 22nM, which is much lower than the therapeutic lowest abnormal concentrations of DA in urine (0.57μM) and blood (16μM) samples. Furthermore, the selectivity and potential applicability of the developed method in spiked actual biological (human plasma and urine) specimens were investigated, suggesting that the present assay could satisfy the requirements for clinical diagnostics and biosensors.

A novel ionic liquid functionalized graphene oxide supported gold nanoparticle composite film for sensitive electrochemical detection of dopamine

A simple and sensitive electrochemical sensor for detection of dopamine has been developed based on ionic liquid functionalized graphene oxide supported gold nanoparticles (GO-IL-AuNPs) coated onto a glassy carbon electrode.

Ag2S quantum dots in situ coupled to hexagonal SnS2 with enhanced photocatalytic activity for MO and Cr(vi) removal

A highly efficient visible-light-driven composite photocatalyst of Ag₂S quantum dots coupled to hexagonal SnS₂ exhibited considerably increased photocatalytic activity for MO and Cr(vi) removal.

Multiwalled carbon nanotube supported Schiff base copper complex inorganic nanocomposite for enhanced electrochemical detection of dopamine

A MWCNT/[Cu(sal-ala)bpy] inorganic nanocomposite for the electrochemical detection of dopamine (DA).