Functionalized Acupuncture Needle as Surface-Enhanced Resonance Raman Spectroscopy Sensor for Rapid and Sensitive Detection of Dopamine in Serum and Cerebrospinal Fluid.

It is a challenge to develop a robust sensor for simple, rapid operation and sensitive detection of neurotransmitters in complex specimens. Herein, ferric citrate functionalized gold nanoparticles (CA-FeIII /Au NPs) are utilized to develop a facile sensor based on surface-enhanced resonance Raman spectroscopy (SERRS) for sensitive detection of dopamine (DA). The sensor is prepared by decorating the acupuncture needle with Au NPs, which enables sufficient surface-enhanced Raman spectroscopy enhancement. The CA-FeIII structure is highly sensitive and selective for DA due to the formation of the CA-FeIII -DA resonant structure; this indicates the advantages of capturing, carrying, and separating DA molecules from complicated samples in a simple operation. Furthermore, the practical application of the fabricated sensor is validated by the detection of DA in pretreated serum and cerebrospinal fluid of acupuncture-treated mice with detection limits of 0.1 and 2.5 nm DA, respectively. The developed active acupuncture needle sensor has potential benefits for sensitive detection and qualitative identification of DA molecules from biological samples.