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The direct detection of dopamine (DA) in human body fluids is a great challenge for medical diagnostics of neurological disorders like Parkinson's disease, Alzheimer's disease, senile dementia, and schizophrenia. In this work, a simple and turn off luminescence sensing of DA based on bovine serum albumin (BSA)-capped manganese-doped zinc sulphide quantum dots (Mn:ZnS/BSA QDs) is developed. The Mn:ZnS/BSA QDs were synthesized by a chemical co-precipitation method. Due to the special interaction of DA with BSA and metal ions, Mn:ZnS/BSA QDs can serve as an effective sensing platform for DA. The luminescence of Mn:ZnS/BSA QDs decreased linearly with increasing concentration of DA in the range from 6.6 to 50.6 nM. The limit of detection is 2.02 nM. The driving force for the luminescence quenching is partly provided by ground-state complex formation of QDs with DA. The photo-induced electron transfer from the conduction band of QDs to oxidized dopamine (quinone) also favors quenching. The Mn:ZnS/BSA QDs are barely interfered with by other competing biomolecules except catecholamine neurotransmitter like epinephrine. Moreover, this method is used in the analysis of DA-spiked human serum and human urine samples and good recovery percentages are found. To assess the utility of the developed sensor, paper strip assay was also successfully conducted. Graphical abstract.

The authors describe blue-green emitting nitrogen doped carbon dots (NCDs) synthesized through a microwave assisted polyol method and by using lactose as the carbon source, ammonium chloride as nitrogen source and PEG 200 as the reaction medium. The surfaces of the NCDs is rich in carboxy groups and can be functionalized with aminophenylboronic acid (APBA) to obtain APBA-modified carbon dots which are shown to a viable fluorescent probe for dopamine (DA). Operated best at excitation wavelength of 370 nm, the fluorescence of the probe increases with increasing concentration of DA. The detection limit is as low as 89 pM. The probe has good selectivity for DA over other interfering neurotransmitters, saccharides, amino acids and antioxidants. It was successfully employed for the detection of DA in (spiked) human serum samples and gave good recoveries. [ABSTRACT FROM AUTHOR]

Graphical abstract depicting detection of dopamine based on BSA stabilised copper nanocluster. • Rapid detection of dopamine is achieved by using insitu synthesized blue emitting CuNC. • Dopamine showed fast response towards H2O2 added BSA CuNC with a limit of detection 0.1637 pM. • Dopamine detection is further validated with real sample matrices such as human blood serum samples and urine samples. • Dopamine detection is further validated with real sample matrices such as human serum samples and human urine samples. • A portable paper strip detection method is developed for the onsite detection of dopamine. Rapid and real-time monitoring of catecholamine neurotransmitter dopamine receives immense importance since it plays a crucial role as a local chemical messenger for interneuronal communications in mammalian central and peripheral nervous systems. In the present study, blue emitting copper nanocluster was synthesized in presence (BSA CuNC1) and absence (BSA CuNC2) of hydrogen peroxide and fluorescence response of the two systems towards dopamine was analysed. At an excitation of 355 nm, fast response towards dopamine detection was obtained for BSA CuNC1 system having limit of detection 0.1637 pM. The fast interaction of dopamine with BSA CuNC1 can be attributed to the intrinsic peroxidase like activity of CuNC in presence of H 2 O 2. On the other hand, the response of dopamine towards BSA CuNC2 was very slow with a limit of detection 0.024 nM. Encouraged by the fast response and low limit of detection, the BSA CuNC1 system was effectively applied for dopamine detection in real sample matrices. The recovery percentage for serum sample obtained was in the range 90–98.33% and for urine sample was in the range 89–96.66%. In addition to that, a paper test strips using BSA CuNC1 was developed which exhibited colour change as well as fluorescence quenching, creates a low cost approach for the fast monitoring of dopamine. [ABSTRACT FROM AUTHOR]