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We used DFT to investigate the aspirin adsorption behavior onto the ZnO nanocage substrate. Almost all possible adsorption mechanisms and corresponding geometries of the aspirin drug over ZnO were studied. The findings indicate that the favorability of the process of adsorption via the –C = O side of the drug is more regarding the energy compared to the other sides of the drug. Located on the zinc atoms in the, the binding sites are eligible according to opposite charge-based interactions. It was found that the charge is transferred from the substrate to the adsorbate according to NBO analysis. The formation of physical bonds was verified by the projected density of states analysis. Furthermore, the AP-ZnO complex showed that the LUMO was mainly localized on the adsorbate species. On the contrary, we observed the highest electronic densities associated with HOMOs at the surface of the ZnO in the most energetically favorable configurations. [ABSTRACT FROM AUTHOR]

Hordenine is an active compound found in several foods, herbs and beer. In this work, a novel sorbent was fabricated for selective solid-phase extraction (SPE) of hordenine in biological samples. The organic polymer sorbent was synthesized in one step in the plastic barrel of a syringe by a pre-polymerization solution consisting of methacrylic acid (MAA), 4-vinylphenylboronic acid (VB) and ethylene glycol dimethacrylate (EGDMA). The conditions for preparation were optimized to generate a poly(MAA-VB-EGMDA) monolith with good permeability. The monolith exhibited good enrichment efficiency towards hordenine. By using tyramine as the internal standard, a poly(MAA-VB-EGMDA)-based SPE-HPLC method was established for analysis of hordenine. Conditions for SPE, including volume of eluting solvent, pH of sample solution, sampling rate and sample volume, were optimized. The proposed SPE-HPLC method presented good linearity ( R2 = 0.9992) within 10-2000 ng/mL and the detection limits was 3 ng/mL, which is significantly more sensitive than reported methods. The method was also applied in plasma and urine samples; good capability of removing matrices was observed, while hordenine in low content was well extracted and enriched. The recoveries were from 90.6 to 94.7% and from 89.3 to 91.5% for the spiked plasma and urine samples, respectively, with the relative standard deviations <4.7%. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]