Fingerprint characterization of M-EDTA complexes and iron compounds using terahertz time-domain spectroscopy

RS, S (+) - and R (-)-ibuprofen cocrystal polymorphs: Vibrational spectra, XRD measurement and DFT calculation studies

In this paper, cocrystal polymorphs of RS-ibuprofen (RS-IBU), S (+)-ibuprofen (S(+)-IBU), R (-)-ibuprofen (R(-)-IBU) with nicotinamide (NIC) were synthesized by different methods. RS-IBU is a chiral drug with only one chiral center in the molecule, which has two enantiomers (S (+)-IBU and R (-)-IBU). Due to the low solubility and bioavailability of IBU, its application is limited. The pharmaceutical cocrystal technology can improve the physicochemical properties of the drug. In this paper, we characterized RS-IBU, S (+)-IBU, R (-)-IBU, NIC, physical mixtures and cocrystal polymorphs by terahertz (THz), Raman and X-ray Diffraction (XRD), respectively. By observing the experimental results, we could clearly distinguish the cocrystal polymorphs. We found that the melt recrystallization method can generate cocrystal form A, while the solvent drop grinding method and solution evaporation method can generate cocrystal form B. In addition, in order to verify the successful preparation of them, we used density functional theory (DFT) to optimize and simulate the theoretical structures of the RS-IBU: NIC cocrystal polymorphs, and compared the simulated results with the experimental results. These research results provide a reference for the analysis and preparation of pharmaceutical cocrystal polymorphs and help to distinguish the cocrystal polymorphs.

Flexible terahertz metamaterial biosensor for label-free sensing of serum tumor marker modified on a non-metal area

Terahertz (THz) metamaterials for rapid label-free sensing show application potential for the detection of cancer biomarkers. A novel flexible THz metamaterial biosensor based on a low refraction index parylene-C substrate is proposed. The biomarkers are modified on non-metal areas by a three-step modification method that simplifies the modification steps and improves the modified effectivity. Simulation results for non-metal modification illustrate that a bulk refractive index sensitivity of 325 GHz/RIU is achieved, which is larger than that obtained for the traditional metal modification (147 GHz/RIU). Meanwhile, several fluorescence experiments proved the uniform modification effect and selective adsorption capacity of the non-metal modification method. The concentration of the carcinoembryonic antigen (CEA) biomarkers for breast cancer patients tested using this THz biosensor is found to be consistent with results obtained from traditional clinical tests. The limit of detection reaches 2.97 ng/mL. These findings demonstrate that the flexible THz metamaterial biosensor can be extensively used for the rapid detection of cancer biomarkers in the future.