# Rod-Shaped NanoZnTPyP Paper-Based Sensor for Visual Detection of Dopamine in Human Plasma

## TL;DR

A new paper-based sensor using nanoZnTPyP and CdTe quantum dots can visually detect dopamine in human plasma with high sensitivity and selectivity.

## Contribution

A novel rod-shaped nanoZnTPyP-based fluorescence paper sensor for sensitive and visual detection of dopamine in physiological samples.

## Key findings

- The sensor detects dopamine in the range of 0.5–10 nmol/L with a limit of detection of 0.38 nmol/L.
- The sensor successfully detected dopamine in human plasma with high selectivity against interfering substances.
- The fluorescence recovery mechanism involves the oxidation of dopamine to DA-quinine and its interaction with nanoZnTPyP.

## Abstract

Dopamine (DA) is a catecholamine neurotransmitter secreted by the human adrenal medulla and is related to many medical diseases. The rapid and sensitive detection of DA levels in physiological media is attracting attention. This paper has developed a fluorescence paper-based sensor using CdTe quantum dots (QDs)-rod nanozinc 5, 10, 15, 20-tetra (4-pyridyl)−21H-23H-porphine (nanoZnTPyP) for sensitive and visual detection of DA. After adding DA, the original quenching fluorescence of the CdTe QDs-rod nanoZnTPyP sensor was effectively restored. The detection mechanism may be that the oxidation of DA to the alkaline CdTe QDs-rod nanoZnTPyP solution produced DA-quinine, and the recovery of fluorescence was caused by the electronic effect of DA-quinine and rod-shaped nanoZnTPyP. The detection range is 0.5∼10 nmol/L, and the limit of detection (LOD) is 0.38 nmol/L (S/N = 3). The sensor system was used on paper device to detect significant changes in the fluorescent color of DA at different concentrations. In addition, this method has been successfully used for the determination of DA in human plasma. The sensor system is simple, easy to operate, and has high selectivity for possible DA interfering substances, which provided new ideas for detecting DA and Parkinson's disease, Alzheimer's disease, and other DA-related diseases.