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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. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ce-MOF is used as a molecular probe of RRS to quantitatively detect trace formaldehyde. • Formaldehyde derivative and Ce-MOF were coupled to generate energy transfer. • This method aims to combine the traditional spectrophotometric with the existing RRS technology. • A convenient detection of trace formaldehyde is realized. Formaldehyde (HCHO) is a widespread toxic pollutant, and the content of formaldehyde in food directly affects human health. Therefore, it is particularly important to establish and develop a rapid and accurate method for the determination of trace formaldehyde to ensure food safety. Metal-organic framework (MOF) has the characteristics of both organic and inorganic materials, which can be applied in various fields. What's more, Cerium (Ce) is the most abundant rare earth element. So far, it has no report about using Ce-MOF as a molecular probe of resonance Rayleigh scattering (RRS). The purpose of this research is to establish a new method for formaldehyde by combining the highly selective acetylacetone reaction with the sensitive RRS technology. When formaldehyde is added, acetylacetone reacts with it to form a complex (DDL), which acts as an accepter. There is a RRS-energy transfer (ET) between the DDL and Ce-MOF (act as the donor) because of spectral overlap. As a result, the RRS intensity of the Ce-MOF system decreased with formaldehyde concentration increase. So, Ce-MOF is used as a molecular probe of RRS to detect formaldehyde. In this study, the detection limit of formaldehyde was 0.063 µmol/L, and the determination range was 0.067–66.67 µmol/L. Compared with other methods, this method is simple in pretreatment and operation, and has a lower detection limit. Thus, a convenient detection of trace formaldehyde is realized. [ABSTRACT FROM AUTHOR]