What is it about?

Dopamine (DA) is one of the most important catecholamine neurotransmitters of the human central nervous system, and is involved in many behavioral responses and brain functions. Below normal DA levels in biological fluids can lead to different neurodegenerative conditions. For excess DA levels, a failure in energy metabolism is indicated. In this study, a facile room-temperature phosphorescence sensor is developed to detect DA based on l-cysteine capped Mn doped ZnS quantum dots (l-cys ZnS:Mn QDs). The QDs display a prominent orange emission band peaking at ~598 nm, which is strongly quenched upon addition of DA in alkaline medium. The sensor exhibits a linear working range of ~0.15–3.00 μM, and a limit of detection of ~7.80 nM. These results are explained in terms of a pH-dependent electron transfer process, in which the oxidized dopamine quinone functions as an efficient electron acceptor. The QDs-based sensor shows a high selectivity to DA over common interfering biomolecules (including some amino acids, ascorbic acid, chloride and glucose). The sensor has been successfully applied for the detection of DA in urine samples, yielding recoveries as high as 93%. Our findings indicate that our developed sensor exhibits high sensitivity and reproducibility to determine DA even in biological fluids where DA is at low levels, e.g., in the central nervous system, which is the usual clinical profile of a neurodegenerative disorder associated to the Parkinson's disease.

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Why is it important?

We establish critical parameters to detect dopamine at concentrations as low as that associated to the neurodegenerative disorder in Parkinson's disease.

Perspectives

The US National Institute of Neurological Disorders classifies Parkinson's disease as the second most common neurodegenerative disorder; affecting approximately one million of people in the US. This disease is related to the loss of brain cells that produce dopamine (DA). DA is one of the most important catecholamine neurotransmitters of the human central nervous system, and is involved in many behavioral responses and brain functions. Abnormal levels of DA have been associated to several diseases. For instance, schizophrenia and aprosexia can result from deficient levels of DA, while pleasurable/rewarding feelings (even euphoria) and failure in energy metabolism are observed when in excess. This makes the selective and sensitive detection of DA of paramount importance in health clinics and the pharmaceutical industry. In this study, we have designed a room-temperature phosphorescence sensor based on L-cysteine capped Mn doped ZnS quantum dots (QDs) to detect dopamine with high sensitivity and selectivity at concentrations as low as that associated to the neurodegenerative disorder in Parkinson's disease.

Dr Juan Beltran-Huarac
Harvard University

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This page is a summary of: L-cysteine capped ZnS:Mn quantum dots for room-temperature detection of dopamine with high sensitivity and selectivity, Biosensors and Bioelectronics, January 2017, Elsevier,
DOI: 10.1016/j.bios.2016.09.022.
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