QDs@MIP nanocomposites: Sensetive sensors for the selective detection of dopamine

In a new study published in Nanomaterials journal, a team of Iranian and French scientists have introduced a new form of nanocomposites that consists of molecularly imprinted polymer (MIP)-modified core/shell CdTe0.5S0.5/ZnS quantum dots (QDs). This nanocomposite acts as a photoluminescence sensor and can detect dopamine in very low concentrations.

Detection of dopamine in biological samples

Dopamine (DA) is an important neurotransmitter which regulates many physiological processes in cardiovascular, nervous and endocrine systems. Unusual concentrations of dopamine in biological fluids are a sign of neurological disorders including Parkinson’s disease, Huntington’s disease and schizophrenia. Thus it is crucial to improve methods that can detect dopamine with high sensitivity.

In recent years various methods have been developed to detect dopamine. However, each of these methods has its own advantages and disadvantages. For example, chromatography techniques take a lot of time and require very complicated steps. Also, detecting dopamine in very low concentrations (10 nM to 10 µM) is a big challenge on its own. Fluorescence spectroscopy is a sensitive and low-cost method which is an ideal candidate for detecting low concentrations of dopamine.

Sensitive detection with the help of QDs@MIP

In a joint effort, researchers from Kharazmi University in Iran and Université de Lorraine in France introduced a composite which is made up of molecularly imprinted polymer and quantum dots. MIP has the ability to recognize target molecules and has very high stability in different conditions. Quantum dots have unique optical and electronic features and also high optical stability. Researchers combined MIP with QDs to build a nanocomposite which is selective and highly sensitive to light. Researchers used acrylamide as functional monomer that creates bonds with DA, and ethylene glycol dimethylacrylate (EGDMA) as cross-linker.

Quantum dots were added to the reaction after the initiation of polymerization. After polymeraztion, hydrogen bonds were broken and DA template was removed from the polymer structure, leaving behind empty 3-dimensional structures. QDs exhibited high photoluminescence (PL) following removal of dopamine. After addition of DA, scientists observed a linear decrease in PL in ranges from 2.63 µM to 26.30 µM of DA with a limit of detection of 6.6 nM. It was shown that these particles are able to detect dopamine in very low concentrations (4.3 ngr/ml). Based on the observations regarding the quenching of QDs PL intensity following addition of DA, scientists concluded that QDs@MIP nanocomposites are able to detect dopamine better than other cellular molecules including amino acids, peptides, vitamins and other neurotransmitters.

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