Abstract
A new method for the determination of oxytetracycline (OTC) has been established by coupling the catalytic amplification reaction of copper nanoclusters (CuNCs) with the aptamer reaction. CuNCs prepared by a wet chemical method have the catalytic activity for the formation of gold nanoparticles (AuNPs) resulting from a HAuCl4-ethanol (En) reaction. The experimental results showed that OTC aptamer (Apt) can be adsorbed on the surface of CuNCs in a non-specific way, thus inhibiting its catalytic activity. When OTC was added to the solution, the OTC-Apt complex was generated by a specific reaction, which made the CuNCs desorb and restore their catalytic activity. With the increase of OTC, the recovery of the catalytic activity of CuNCs is strengthened, the reaction speed is accelerated, and the number of AuNPs is increased. The generated AuNPs exhibited surface enhanced Raman scattering (SERS) signals at 1615 cm−1 in the presence of Vitoria blue 4R (VB4R) molecular probes, and a resonance Rayleigh scattering (RRS) peak at 586 nm. There is a good linear relationship between the intensities of SERS, or RRS, and OTC concentration at the range of 37.5–300 ng/L or 37.5–225 ng/L, respectively. A new SERS and RRS assay for the determination of trace OTC based on the regulation of CuNCs catalysis was established.
Highlights
The addition of CuNCs can greatly catalyze the reaction of HAuCl4 -ethanol, generating more AuNPs and stronger resonance Rayleigh scattering (RRS) signals
After the addition of OTC, the Apt was desorbed from the surface of the CuNCs due to the specific binding between the OTC and Apt, and the catalytic activity of the CuNCs was restored
CuNCs with high catalytic activity were prepared using a simple method, and their morphology was characterized by SEM and TEM
Summary
Metal nanoclusters have attracted much attention because of their unique physical, chemical, and optical properties, and have become a hot research field in recent decades [1]. Copper, which is in the same group as gold and silver, has attracted extensive attention. The preparation conditions of CuNCs are simple, and it has been proved experimentally that CuNCs have similar advantages to gold and silver nanoclusters in optical properties [3]. The preparation of CuNCs in the laboratory is usually directly reduced by using a wet chemical method, which involves adding reductive substances to make copper ions recover in the solution to produce Cu atom particles, which are further clustered until CuNCs are obtained [4]. In combination with different methods to improve the stability of CuNCs, more synthesis
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