The quality of food is one of the emergent points worldwide. Many microorganisms produce toxins that are harmful for human and animal health. In particular, mycotoxins from Fusarium fungi are strictly controlled in cereals. Simple and robust biosensors are necessary for ‘in field’ control of the crops and processed products. Nucleic acid-based sensors (aptasensors) offer a new era of point-of-care devices with excellent stability and limits of detection for a variety of analytes. Here we report the development of a surface-enhanced Raman spectroscopy (SERS)-based aptasensor for the detection of T-2 and deoxynivalenol in wheat grains. The aptasensor was able to detect as low as 0.17% of pathogen fungi in the wheat grains. The portable devices, inexpensive SERS substrate, and short analysis time encourage further implementation of the aptasensors outside of highly equipped laboratories.
22 July 2022 in Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
The expansion of the range of physico-chemical methods in the study of industrially significant α-olefin oligomers and polymers is of particular interest. In our article, we present a comparative Raman study of structurally uniform hydrogenated dimers, trimers, tetramers, and pentamers of 1-hexene and 1-octene, that are attractive as bases for freeze-resistant engine oils and lubricants. We found out that the joint monitoring of the disorder longitudinal acoustic mode (D-LAM) and symmetric C–C stretching modes allows the quantitative characterization of the number and length of alkyl chains (i.e., two structural characteristics), upon which the pour point and viscosity of the hydrocarbons depend, and to distinguish these compounds from both each other and linear alkanes. We demonstrated that the ratio of the contents of CH2 and CH3 groups in these hydrocarbons can be determined by using the intensities of the bands in the spectra, related to the asymmetric stretching vibrations of these groups. The density functional theory (DFT) calculations were applied to reveal the relations between the wavenumber and bandshape of the symmetric C–C stretching mode and a conformation arrangement of the 1-hexene and 1-octene dimers. We found that the branched double-chain conformation results in the splitting of the C–C mode into two components with the wavenumbers, which can be used as a measure of the length of branches. This conformation is preferable to the extended-chain conformation for hydrogenated 1-hexene and 1-octene dimers.
Anhydrofusarubin is a naphthoquinone pigment synthesized by a number of Fusarium genus fungi. Being a biologically active substance, it demonstrates promising antibiotic properties and rather good hypothetical effectiveness against certain types of cancer. In this regard, an important task arises to study the structural properties and spectral manifestation of Anhydrofusarubin in order to identify and characterize this substance in terms of synthesis and application purposes. In this regard, the aim of the article was to study the structure of the Anhydrofusarubin molecule and its structure-property correlation. The density functional theory was used to investigate the optical properties and stability of the molecular structures. The computational results obtained with B3LYP and wb97XD exchange correlation functionals and the triple zeta basis sets were compared with available experimental data. In addition to the ground state structure, a tautomer with slightly higher energy (by 0.78–0.9 kcal/mol) and a relatively small potential barrier was found. Also, the investigation of flexibility of the pyran ring reveals the presence of two conformational enantiomer forms, being in good agreement with the recent experimental data on the crystal structure. The vibrational and UV-visible absorption spectra were simulated and interpreted.