In this study, two types of spent coffee grounds (SCG, Machine and Turkish) were tested in the production of SCG-biopolymer composite cups. The ob-jective was to develop a simple and sustainable preparation approach for SCG-based biocomposites, ensuring sufficient mechanical and thermal sta-bility for practical applications. Biocomposite cups, containing 55 to 72% of SCG were produced using sodium alginate as the primary polymer binder. To enhance mechanical performance, a secondary binder (additional poly-mer), either cellulose ether (carboxymethyl cellulose (CMC) or hydroxy-propyl cellulose (HPC)) or natural polysaccharides (dextran or pectin), was incorporated. Comprehensive characterisation was performed using fluorescence and FTIR spectroscopy, tensile testing, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Fluorescence spectroscopy/microscopy revealed a higher content of naturally fluorescent organic compounds in Machine SCG compared to Turkish SCG. FTIR spec-troscopy confirmed the successful SCG incorporation into the biopolymer matrix. Tensile testing showed that Machine SCG-based biocomposites were slightly more flexible than those prepared with Turkish SCG. Glass transition temperature (Tg) of SCG biocomposites depends on their composition and varied from around 75 to 100 degrees C. The TGA results demonstrated that SCG exhibit a greater thermal stability than both SCG-alginate biocomposites and SCG biocomposites containing additional polymers.
In the search for chemical compounds that strongly and selectively bind and inhibit one out of 12 catalytically active CA isozymes, a series of fluorinated substituted benzenesulfonamides was designed and synthesised. Substituents were intended to be stiff and have a limited conformational flexibility. We determined compound affinities using the fluorescence-based thermal shift assay. Afterward, we subtracted the binding-linked protonation reactions and calculated the intrinsic affinities, which were then used to establish the structure-affinity relationships. Compound 5 (2-(cyclohexylamino)-3,5,6-trifluoro-4-(phenylsulfonyl) benzenesulfonamide) exhibited an improved selectivity profile toward CAIX, a cancer-associated isozyme. The analysis of compound functional group contributions and the comparison with previously designed compounds provided insight toward a deeper understanding of the protein-ligand recognition principles for drug design.
This article describes the synthesis and properties of new methoxy-substituted triphenylamine-based enamines. Thermal, photophysical and electrochemical properties of the compounds are reported. In addition, the ionisation energies estimated by photoelectron emission spectroscopy and hole transporting properties examined by the time-of-flight method are discussed. The compounds form molecular glasses with glass transition temperatures of up to 91 degrees C. They exhibit a high thermal stability with 5% weight-loss temperatures above 420 degrees C. Their characteristic optical band-gaps are of 2.9 eV and the solid-state ionisation energies situate around 5.4 eV. One of the compounds shows a high hole mobility of 8.4 & times; 10-4 cm2/Vs at the electric field of 4 & times; 105 V/cm.
The nanostructuring of electrode surfaces is commonly employed to enhance the electrochemical performance of enzymatic glucose biosensors. However, the optimisation of nanostructure morphology and dimensions remains an incompletely explored area. In this work, three colloidal solutions of gold na-norods (AuNR), different in size, were synthesised. SEM analysis revealed that nanorods exhibited distinct lengths: 32.8 +/- 3.4 nm for AuNRI, 35.0 +/- 3.5 nm for AuNRII and 90.0 +/- 6.7 nm for AuNRIII. Glucose biosensors based on graphite rod electrodes modified with AuNR and glucose oxidase showed enhanced electrochemical performance. Notably, biosensors fabricated with AuNRI and AuNRIII achieved similar maximal current changes during the en-zymatic reaction (triangle Imax = 49.31 +/- 2.64 and 48.45 +/- 2.35 & micro;A, respectively), despite the pronounced difference in the electroactive surface area obtained after AuNR deposition (0.082 +/- 0.009 and 0.194 +/- 0.005 cm2, respectively). Moreover, the fabricated glucose biosensor based on AuNRI exhibited a linear range of practical relevance (0.1-8 mM), a low limit of detection (4.6 & micro;M), and is suitable for glucose detection in the diluted blood serum. Overall, the results indicate that morphological characteristics, including size, aspect ratio, and spatial organisation, play a crucial role in optimising the design and performance of enzymatic glucose biosensors.
The aim of this study was to quantify the actual melatonin content in commonly available over-the-counter melatonin sleep supplements marketed in Lithuania. For this purpose, a high-performance liquid chromatography (HPLC) method was optimised and validated. The calibration curve was linear (R2 = 0.9996) over a concentration range of 0.5-50.0 mg/L, and the limit of detection was 0.17 mg/L. Recoveries of melatonin from spiked supplement samples ranged from 96.8 to 104.1%, with relative standard deviation values below 3.2%. Melatonin was quantified in 20 commercial sleep supplements representing 10 brands and three dosage forms (capsules, tablets and liquids), with two different lots analysed for each brand. Overall, the measured melatonin content ranged from-7 to +26% relative to the labelled amount, indicating a low variability among melatonin products sold in Lithuania. Only one product contained melatonin amount outside the +/- 20% margin of the labelled claim. The least variable products were liquid supplements, which generally contained the simplest ingredient compositions.
