Synchronous fluorescence spectroscopy for detecting blood meal and blood products

Derivative Matrix-Isopotential Synchronous Spectrofluorimetry and Hantzsch Reaction: A Direct Route to Simultaneous Determination of Urinary δ-Aminolevulinic Acid and Porphobilinogen

Early and sensitive detection of δ-aminolevulinic acid (δ-ALA) and porphobilinogen (PBG) is the cornerstone of diagnosis and effective treatment for acute porphyria. However, at present, the quantifying strategies demand multiple solvent extraction steps or chromatographic approaches to separate δ-ALA and PBG prior to quantification. These methods are both time-consuming and laborious. Otherwise, in conventional spectrofluorimetry, the overlapping spectra of the two analytes cause false diagnosis. To overcome this challenge, we present a two-step approach based on derivative matrix-isopotential synchronous fluorescence spectrometry (DMISFS) and the Hantzsch reaction, realizing the simple and simultaneous detection of δ-ALA and PBG in urine samples. The first step is chemical derivatization of the analytes by Hantzsch reaction. The second step is the determination of the target analytes by combining MISFS and the first derivative technique. The proposed approach accomplishes following advantages: 1) The MISFS technique improves the spectral resolution and resolves severe spectral overlap of the analytes, alleviating tedious and complicated pre-separation processes; 2) First derivative technique removes the background interference of δ-ALA on PBG and vice versa, ensuring high sensitivity; 3) Both the analytes can be determined simultaneously via single scanning, enabling rapid detection. The obtained detection limits for δ-ALA and PBG were 0.04 μmol L−1 and 0.3 μmol L−1, respectively. Within-run precisions (intra and inter-day CVs) for both the analytes were <5%. Further, this study would serve to enhance the availability of early and reliable quantitative diagnosis for acute porphyria in both scientific and clinical laboratories.

Dual-mode turn-on ratiometric fluorescence sensor based on carbon dots and CuInS2/ZnS quantum dots for detection of chlorotetracycline

A new ratiometric fluorescence sensor is prepared for selective detection of chlorotetracycline (CTC) through dual-mode fluorescence method. The sensor is composed of carbon dots (CDs) with blue emission and carboxyl-modified CuInS₂/ZnS quantum dots (QDs) with dark-red emission. Usually QDs are used as fluorescent probes or signal sources, but it is interesting in this strategy that CuInS₂/ZnS QDs innovatively work as quenching agent to reduce the fluorescence of CDs, mainly due to the fluorescence resonance energy transfer (FRET). After the addition of CTC, the interaction between CDs and CuInS₂/ZnS QDs is restrained, resulting in the fluorescence recovery of CDs, whilstthe QDs' fluorescence remains unaffected. In this work, CTC is detected in the range of 0-50 μM by conventional fluorescence and synchronous fluorescence methods under an excitation wavelength of 360 nm or Δλ = 90 nm, and the detection limits of the two methods are 0.46 μM and 0.36 μM, respectively. The designed sensor displays good selectivity compared with other tetracycline drugs with similar structure to CTC, different ions and various natural - amino acids. And the sensor can also be applied to determine CTC in tap water and milk.

Official Feed Control Linked to the Detection of Animal Byproducts: Past, Present, and Future

In the context of the expansion of the human population, availability of food, and in extension of animal feed, is a big issue. Favoring a circular economy by the valorization of byproducts is a sustainable way to be more efficient. Animal byproducts are an interesting source of feed materials due to their richness in proteins of high nutritional value. Prevention and control efforts have allowed a gradual lifting of the feed ban regarding the use of animal byproducts. Nevertheless, the challenge remains the development of analytical methods enabling a distinction between authorized and unauthorized feed materials. This Review focuses on the historical and epidemiological context of the official control, the evaluation of current and foreseen legislation, and the available methods of analysis for the detection of constituents of animal origin in feedingstuffs. It also underlines the analytical limitations of the approach and discusses some prospects of novel methods to ensure food and feed safety.

Fluorometric determination of the CCAAT/enhancer binding protein alpha by using gold nanoparticles and a labeled protein-binding DNA

A method is described for the determination of the CCAAT/enhancer binding protein alpha (C/EBPα) which is a regulator in adipocyte differentiation. The method is based on quenching of the red fluorescence (with excitation/emission maxima at 548/562 nm) of Cy3-labeled DNA if it becomes adsorbed on positively charged gold nanoparticles (AuNPs). Fluorescently labeled dsDNA that can bind C/EBPα is introduced as a fluorescent probes. The dsDNA is electrostatically adsorbed on the positively charged AuNPs to quench their fluorescence. In the presence of C/EBPα, it will bind dsDNA which then diffuses away. The fluorescence of the AuNPs becomes restored. The fluorescent signal increases linearly in the 0.05 to 600 ng·mL^-1 μM C/EBPα concentration range, and the detection limit is 29 pg·mL^-1. The method is specific and was applied to analyze cell lysates and in-situ. Graphical abstractSchematic representation of a fluorometric method for determination of the CCAAT/enhancer binding protein alpha (C/EBPα). Fluorescently labeled dsDNA that can bind C/EBPα is introduced as a fluorescent probes. The dsDNA is electrostatically adsorbed on the positively charged AuNPs to quench their fluorescence. In the presence of C/EBPα, it will bind dsDNA which then diffuses away. The fluorescence of the AuNPs becomes restored.