ACS Omega最新文献

For the first time, Zn/Cr-containing layered double hydroxides (LDH) and mixed metal oxides (MMO) were applied in the synthesis of 5-substituted 1H-tetrazole heterocycles from different aromatic nitriles and TMSN₃ (trimethylsilyl azide) as a less explosive/toxic and easily recoverable azide source. Effects of the nitrile concentration, reaction time, temperature, catalyst loading, and amount of N₃ ^- source were carefully investigated to achieve high yields and selective tetrazole formation under the most sustainable conditions. Both Zn _x Cr-LDH and -MMO (prepared based on thermogravimetric analysis) catalyst forms were efficient in the reaction (achieving between 60 and 95% conversion), and Zn₃Cr-LDH tolerated nitriles containing different electron-withdrawing and -donating substituents well. The catalyst was recycled five times and characterized by X-ray diffractometry, transmission, and scanning electron microscopy with energy-dispersive X-ray analysis, infrared, and Raman spectroscopic techniques. Based on the tests, excellent catalyst reusability results (over 80% conversion and 100% selectivity even at the fifth use) were due to the robustness of the catalytic surface. The performance of zinc-rich Zn₃Cr-LDH catalyst rivaled that of many extreme and noticeably expensive metal-containing materials (Cu, Pd, La), and it was also highly effective for use in DMSO solvent approved for medical research. For the extension of tetrazole synthesis, four new nitriles of kynurenic acid (glutamate receptor antagonists, potential neuroprotective agents with modified blood-brain barrier permeability) were synthesized and fully characterized by nuclear magnetic resonance and mass spectroscopic analyses.

Erbium-doped yttrium oxide nanoparticles (Er:Y₂O₃ NPs) with a log-normal size distribution peaking at 43 nm were synthesized and coloaded with PEG and folic acid (FA) to achieve tumor cell targeting while maintaining good water dispersibility. Structural and optical analyses (TEM, FTIR, PL, upconversion) confirmed successful functionalization without significant alterations in the fluorescence signal. In colorectal cancer cells (HCT-116), MTT assays showed >80% viability for concentrations of NPs between 0.1 and 1 μg/mL, indicating low cytotoxicity. Confocal microscopy revealed fluorescence signals consistent with potential nanoparticle internalization, although contrast was limited by cellular autofluorescence. ICP-OES quantification supported greater internalization of PEG-FA nanoparticles compared to PEG nanoparticles, confirming the role of FA in enhancing internalization. Moreover, NIR excitation (980 nm) suppressed cellular autofluorescence, suggesting the potential of these nanoparticles for high-contrast bioimaging applications.

Extracellular vesicles (EVs) are crucial in many physiological and pathological processes, and therefore, they are increasingly studied for their potential as diagnostic biomarkers, therapeutic agents, and drug carriers. Red-blood-cell-derived EVs (REVs) have gained particular interest due to their beneficial properties for drug delivery and their unique biophysical and molecular characteristics, which make them a practical model system for EV research. While EV cryopreservation methods have advanced in the past decade, REVs remain relatively understudied, with their hemoglobin-rich composition presenting unique storage challenges. To address this gap, we investigated how the vesicle concentration and buffer composition affected REV preservation to identify the best storage conditions. We evaluated changes in protein and lipid contents, hemoglobin retention, particle recovery, size distribution, and optical properties using a variety of analytical methods. Our results show that phosphate-buffered saline (PBS), despite its common use, leads to significant losses in vesicle number and major compositional changes. While human serum albumin (HSA) alone showed no protective effect, the combined action of HEPES, HSA, and trehalose (PBS-HAT) preserved the biochemical and biophysical integrity of REVs much more effectively. Furthermore, we found that the initial REV concentration at the time of freezing significantly affected particle recovery but not the composition of the EVs. Notably, a loss in particle concentration (30%) was already evident at an initial concentration of 1.2 × 10¹¹ particles/mL. Our findings demonstrate that PBS-HAT offers an effective strategy for the short- to midterm cryopreservation of REVs above the initial concentration of 10¹² particles/mL.