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A new magnetic-liquid crystal nanosurface molecularly imprinted polymer (5CB-Fe 3 O 4 @MIP) resonance Rayleigh scattering temperature sensor was prepared, using liquid crystal 4'-cyano-4'-pentylbiphenyl as the temperature sensing element, nano-Fe 3 O 4 as the substrate, methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as the crosslinking agent. It was characterized by molecular spectroscopy, scanning electron microscopy and Fourier transform infrared spectroscopy. The thermosensitive effect of 11 liquid crystals, that is, the relationship between RRS and temperature, was studied. The 4'-cyano-4'-pentylbiphenyl exhibits best sensitive. The 5CB-Fe 3 O 4 @MIP temperature sensor had a strong resonance Rayleigh scattering peak at 370 nm. The resonance Rayleigh scattering intensity increased with the increase of temperature, and showed a good linear relationship. The temperature range of measurement was 30-95 °C, with a slope of 16.8 a.u./°C. And by optimizing the preparation conditions of molecularly imprinted polymers, the best preparation conditions were obtained: template molecule: 0.25 mmol, functional monomer: 2.5 mmol, cross-linker: 5 mmol, reaction temperature: 70 °C, reaction time: 2.5 h. As a comparison, we also studied the effect of Fe 3 O 4 with different particle sizes on the 5CB-Fe 3 O 4 @MIP temperature sensor. At the same time, the temperature sensor is applied to the temperature measurement of cooling water, which is effective., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In this paper, a new dimode scattering spectral method for rapid detection of ultratrace melamine (ML) in dairy products was established by coupling nanosurface molecular imprinting technology with nanocatalytic amplification reaction of liquid crystal particles. It was found that liquid crystal cholesteryl butyrate (CBU) nanosurface imprinted polymers (CBU@MIP) not only recognized ML but also catalyzed the nano indicator reaction of HAuCl 4 -sodium formate to produce gold nanoparticles with surface-enhanced Raman scattering (SERS) and resonance Rayleigh scattering (RRS) effect. When ML was added, it specifically combined with CBU@MIP to form CBU@MIP-ML conjugates with strong catalytic activity, and SERS and RRS signals increased linearly with the detection limits of 0.0072 pmol/L and 0.093 pmol/L respectively. The method was applied to the determination of ML in dairy products and plastic tablewares with relative standard deviation (RSD) of 2.2-4.4 % and 1.6-4.7 %, and recovery of 95.4 %-108.3 % and 95.9-108.6  % respectively., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Lead ion (Pb 2+ ) is a toxic heavy metal, which is very harmful to organisms. Therefore, the establishment of a rapid, simple, and sensitive method is of great significance to food safety and human health. It was found that MXeneTi 3 C 2 nanosheet (NS) has a strong catalytic effect on the oxidation of 3,3,5,5-tetramethylbenzidine (TMB) via H 2 O 2 to form the oxidized product (TMB OX ); it has a strong fluorescence peak at 415 nm and an absorption (Abs) peak at 295 nm. The aptamer of Pb 2+ (Apt pb ) can be adsorbed on the surface of an NS to form MXene-Apt conjugates, which reduces its catalytic active sites and inhibits its catalytic activity. When the target Pb 2+ is added, it specifically binds with Apt pb to release MXene NSs to enhance the dimode signals. Therefore, a new MXene catalytic fluorescence/absorption dimode aptamer biosenering platform was fabricated for the determination of trace Pb 2+ in milk and water samples, with the fluorescence assay linear range (LR) of 5.0 × 10 -2 -2.0 nmol/L., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Zhi, Wei, Zhang, Yi, Li and Jiang.)