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Selective detection of dopamine in the presence of ascorbic acid via fluorescence quenching of InP/ZnS quantum dots.

Ankireddy SR, Kim J - Int J Nanomedicine (2015)

Bottom Line: The surface of the QDs was modified with l-cysteine by coupling reaction to increase the selectivity of dopamine.The fluorescence of cysteine-capped indium phosphide/zinc sulfide QDs was quenched by dopamine with various concentrations in the presence of ascorbic acid.This method shows good selectivity for dopamine detection, and the detection limit was 5 nM.

View Article: PubMed Central - PubMed

Affiliation: Department of chemical and Biological Engineering, Gachon University, Seongnam, South Korea.

ABSTRACT
Dopamine is a neurotransmitter of the catecholamine family and has many important roles, especially in human brain. Several diseases of the nervous system, such as Parkinson's disease, attention deficit hyperactivity disorder, restless legs syndrome, are believed to be related to deficiency of dopamine. Several studies have been performed to detect dopamine by using electrochemical analysis. In this study, quantum dots (QDs) were used as sensing media for the detection of dopamine. The surface of the QDs was modified with l-cysteine by coupling reaction to increase the selectivity of dopamine. The fluorescence of cysteine-capped indium phosphide/zinc sulfide QDs was quenched by dopamine with various concentrations in the presence of ascorbic acid. This method shows good selectivity for dopamine detection, and the detection limit was 5 nM.

No MeSH data available.


Related in: MedlinePlus

Schematic illustration of the fluorescence quenching of cysteine-capped InP/ZnS QDs in the presence of AA and DA.Abbreviations: InP/ZnS QDs, indium phosphide/zinc sulfide quantum dots; PL, photoluminescence; AA, ascorbic acid; DA, dopamine (3,4-dihydroxyphenethylamine).
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f7-ijn-10-113: Schematic illustration of the fluorescence quenching of cysteine-capped InP/ZnS QDs in the presence of AA and DA.Abbreviations: InP/ZnS QDs, indium phosphide/zinc sulfide quantum dots; PL, photoluminescence; AA, ascorbic acid; DA, dopamine (3,4-dihydroxyphenethylamine).

Mentions: Figure 7 shows the schematic illustration of fluorescence quenching of QDs by AA and DA. The hydroxyl group of catechol ring of DA and ribose ring of AA can be oxidized and acts as a hole trap to quench the fluorescence of QDs. When electrons are transferred from CB of QDs to DA and AA, enolate intermediate ions are formed. Figure 8 shows the schematic representation of AA and dopamine–enolate ion resonance structures. Dopamine and AA is slightly acidic for it to have recognizable acidic properties due to active hydroxyl group on the benzene and ribose rings. When electrons are transferred from QDs to DA and AA, enolate intermediate ions are formed. Dopamine and AA can lose a hydrogen ion because the phenoxide and ascorbate ions were stabilized to some extent. The negative charge on the oxygen atom is delocalized around the ring. The more stable the ion is, the more likely it is to form. One of the lone pairs on the oxygen atom overlaps with the delocalized electrons on the benzene and ribose rings. This overlap leads to a delocalization, which extends from the ring out over the oxygen atom. The dopamine enolate ion is more stable than the ascorbate enolate ion due to its more resonant structures. Due to this stability of enolate intermediate ions, the fluorescence of QDs was quenched more in the presence of DA than AA.


Selective detection of dopamine in the presence of ascorbic acid via fluorescence quenching of InP/ZnS quantum dots.

Ankireddy SR, Kim J - Int J Nanomedicine (2015)

Schematic illustration of the fluorescence quenching of cysteine-capped InP/ZnS QDs in the presence of AA and DA.Abbreviations: InP/ZnS QDs, indium phosphide/zinc sulfide quantum dots; PL, photoluminescence; AA, ascorbic acid; DA, dopamine (3,4-dihydroxyphenethylamine).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4554434&req=5

f7-ijn-10-113: Schematic illustration of the fluorescence quenching of cysteine-capped InP/ZnS QDs in the presence of AA and DA.Abbreviations: InP/ZnS QDs, indium phosphide/zinc sulfide quantum dots; PL, photoluminescence; AA, ascorbic acid; DA, dopamine (3,4-dihydroxyphenethylamine).
Mentions: Figure 7 shows the schematic illustration of fluorescence quenching of QDs by AA and DA. The hydroxyl group of catechol ring of DA and ribose ring of AA can be oxidized and acts as a hole trap to quench the fluorescence of QDs. When electrons are transferred from CB of QDs to DA and AA, enolate intermediate ions are formed. Figure 8 shows the schematic representation of AA and dopamine–enolate ion resonance structures. Dopamine and AA is slightly acidic for it to have recognizable acidic properties due to active hydroxyl group on the benzene and ribose rings. When electrons are transferred from QDs to DA and AA, enolate intermediate ions are formed. Dopamine and AA can lose a hydrogen ion because the phenoxide and ascorbate ions were stabilized to some extent. The negative charge on the oxygen atom is delocalized around the ring. The more stable the ion is, the more likely it is to form. One of the lone pairs on the oxygen atom overlaps with the delocalized electrons on the benzene and ribose rings. This overlap leads to a delocalization, which extends from the ring out over the oxygen atom. The dopamine enolate ion is more stable than the ascorbate enolate ion due to its more resonant structures. Due to this stability of enolate intermediate ions, the fluorescence of QDs was quenched more in the presence of DA than AA.

Bottom Line: The surface of the QDs was modified with l-cysteine by coupling reaction to increase the selectivity of dopamine.The fluorescence of cysteine-capped indium phosphide/zinc sulfide QDs was quenched by dopamine with various concentrations in the presence of ascorbic acid.This method shows good selectivity for dopamine detection, and the detection limit was 5 nM.

View Article: PubMed Central - PubMed

Affiliation: Department of chemical and Biological Engineering, Gachon University, Seongnam, South Korea.

ABSTRACT
Dopamine is a neurotransmitter of the catecholamine family and has many important roles, especially in human brain. Several diseases of the nervous system, such as Parkinson's disease, attention deficit hyperactivity disorder, restless legs syndrome, are believed to be related to deficiency of dopamine. Several studies have been performed to detect dopamine by using electrochemical analysis. In this study, quantum dots (QDs) were used as sensing media for the detection of dopamine. The surface of the QDs was modified with l-cysteine by coupling reaction to increase the selectivity of dopamine. The fluorescence of cysteine-capped indium phosphide/zinc sulfide QDs was quenched by dopamine with various concentrations in the presence of ascorbic acid. This method shows good selectivity for dopamine detection, and the detection limit was 5 nM.

No MeSH data available.


Related in: MedlinePlus