One-pot facile synthesis of bright blue emitting silicon nanoparticles for sensitive detection of luteolin via inner filter effect

Phenylboronic acid-functionalized copper nanoclusters with sensitivity and selectivity for the ratiometric detection of luteolin

A desirable ratiometric fluorescent probe was designed by using 3-carboxyphenylboronic acid functionalized polyethyleneimine ethoxylated modified copper nanoclusters (CPBA@PEI-CuNCs) for detecting luteolin (LTL, cis-diols structure) with sensitivity and selectivity. Characterization techniques were carried out with the TEM, PSD, FT-IR, XPS and XRD, confirming its successful formation with a quantum yield of 40.49 %. As the optimal excitation wavelength at 386 nm, the fluorescence intensity was detected by fluorophotometer. Meanwhile, the nanoprobe has two emission wavelengths 396 and 473 nm. According to the fluorescence quenching intensity ratio (F473/F396), the LOD reached as low as 1.22 nM within the range from 0.11 to 600 μM. The CPBA@PEI-CuNCs exhibited pH-controlled, covalent, and reversible binding properties. Using PEI capped by CuNCs, cytotoxicity is reduced for potential treatment purposes. Additionally, the developed probe was used for LTL detection, HepG2 cell imaging and pH-responsive drug delivery in real samples with carrot leaves, peanut shells, and perilla leaves samples. CPBA@PEI-CuNCs demonstrated repeatability and reproducibility, making it a cost-effective and practical tool for fluorescence analysis in detection.

Selective determination of ellagic acid in aqueous solution using blue-green emissive copper nanoclusters

Development of beneficial sensors to analyze ellagic acid concentrations is of great importance for food safety and human health. Herein, a facile and fast fluorescent probe was carried out for the excellently selective and sensitive measurement of ellagic acid in real samples through histidine protected copper nanoclusters (histidine@Cu NCs) as a nanosensor. This as-developed histidine@Cu NCs were performed through UV-vis absorption spectroscopy, fluorescence spectroscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy and fluorescence lifetime analysis. The TEM image revealed that this nanomaterial had spherical features with the average diameter of 2.5 ± 0.05 nm. The blue-green fluorescence of this Cu NCs was found under the UV light. Meanwhile, the maximum excitation and emission wavelength were located at 387 nm and 488 nm. After addition of ellagic acid, the fluorescence of histidine@Cu NCs was slowly weakened with excellent linear range of 0.5-300 μM and detection limit of 0.077 μM. The fluorescence weakening mechanism of this nanosensor were attributed to the inner filter effect (IFE) and static quenching. Finally, this as-established analysis platform was successfully employed to measure ellagic acid in real samples.

Water Soluble Silicon Nanoparticles as a Fluorescent Probe for Highly Sensitive Detection of Rutin

In this work, water-soluble fluorescent silicon nanoparticles (SiNPs) were prepared by one-pot hydrothermal method using 3-(2-aminoethylamino)propyldimethoxymethylsilane (AEAPDMMS) as a silicon source and amidol as a reducing agent. The prepared SiNPs showed bright green fluorescence, excellent stability against photobleaching, salt tolerance, temperature stability, and good water solubility. Due to the internal filtration effect (IFE), rutin could selectively quench the fluorescence of the SiNPs. Based on such phenomena, a highly sensitive fluorescence method was established for rutin detection. The linear range and limit of detection (LOD) were 0.05-400 μM and 15.2 nM, respectively. This method was successfully applied to detect rutin in the samples of rutin tablets, Sophora japonica, fry Sophora japonica, and S. japonica carbon with satisfactory recovery.