Improving the adsorption potential of chitosan for heavy metal ions using aromatic ring-rich derivatives.

This study describes the simple preparation process of modified chitosan (CS) that can effectively adsorb lead ion in the aqueous medium. To design this adsorbent with high binding sites, the Schiff base ligand with three aromatic rings, 3,3-diphenylpropylimine methyl benzaldehyde (PPIMB), is synthesized. The PPIMB forms several new binding sites in modified CS by making a new imine bond with free NH2 in CS structure. The structural and physicochemical characteristics of the magnetically modified chitosan (MCS-PPIMB) are evaluated by FTIR, XRD, SEM, EDX, DLS, VSM, and TG techniques. The effect of some factors, such as pH, collision time, adsorbent dosage, and initial concentration of Pb(II), is investigated on the adsorption capacity of the adsorbent. The adsorption capacity of MCS-PPIMB against Pb(II) is obtained 230.48 mg/g. The adsorption behavior of MCS-PPIMB is fitted efficiently by the Langmuir isotherm model. The fluorometric studies show that the adsorbent has a sharp emission peak at 698 nm, and Pb(II) ion can quench the fluorescence emission of MCS-PPIMB at low concentration. The theoretical studies confirm the strong binding energy of the Pb atom with aromatic rings and imine groups of the MCS-PPIMB.

Catalytic activity and structural changes of catalase in the presence of Levothyroxine and Isoxsuprine hydrochloride.

Two drugs that pregnant women (with hypothyroidism) may use during pregnancy include Isoxsuprine hydrochloride (ISO) and levothyroxine (LEV); ISO to reduce uterine contractions and LEV for the treatment of hypothyroidism. In the current work, we explored the mechanism of binding affinity between the above drugs and antioxidant enzyme Bovine Liver Catalase (BLC). The experimental results confirmed that both drugs could bind with BLC to form drug-BLC complexes but LEV showed a higher binding affinity toward enzyme. The binding constants of LEV-and ISO-BLC were 0.42 × 105 and 0.13 × 104 M-1 at 310 K, respectively. LEV enhanced the catalase activity but the enzymatic activity of BLC reduced gradually in the presence of ISO. Both drugs were able to induce conformational changes in the BLC structure. The results of the molecular docking investigations confirmed the experimental data and showed that the main binding forces in the LEV-BLC and ISO-BLC systems were hydrogen bond and hydrophobic force. The best binding site of both drugs on BLC is located at a cavity among the wrapping domain, N-Terminal arm, and ß-barrel.