Interaction of Macromolecular Chain with Phospholipid Membranes in Solutions: A Dissipative Particle Dynamics Simulation Study.

The interaction between macromolecular chains and phospholipid membranes in aqueous solution was investigated using dissipative particle dynamics simulations. Two cases were considered, one in which the macromolecular chains were pulled along parallel to the membrane surfaces and another in which they were pulled vertical to the membrane surfaces. Several parameters, including the radius of gyration, shape factor, particle number, and order parameter, were used to investigate the interaction mechanisms during the dynamics processes by adjusting the pulling force strength of the chains. In both cases, the results showed that the macromolecular chains undergo conformational transitions from a coiled to a rod-like structure. Furthermore, the simulations revealed that the membranes can be damaged and repaired during the dynamic processes. The role of the pulling forces and the adsorption interactions between the chains and membranes differed in the parallel and perpendicular pulling cases. These findings contribute to our understanding of the interaction mechanisms between macromolecules and membranes, and they may have potential applications in biology and medicine.

Nanomaterial/ionophore-based electrode for anodic stripping voltammetric determination of lead: an electrochemical sensing platform toward heavy metals.

A novel nanomaterial/ionophore-modified glassy carbon electrode for anodic stripping analysis of lead (Pb(2+)) is described. Nanosized hydroxyapatite (NHAP) with width of 20-25 nm and length of 50-100 nm has been prepared and used to improve the sensitivity for detection of Pb(2+) because it provides unique three-dimensional network structure and has strong adsorption ability toward Pb(2+). An ionophore, usually used in ion-selective electrodes, is utilized here for its excellent selectivity toward Pb(2+). Nafion, a cation-exchange polymer, is employed as the conductive matrix in which NHAP and the ionophore can be tightly attached to the electrode surface. Such a designed NHAP/ionophore/Nafion-modified electrode shows remarkably improved sensitivity and selectivity to Pb(2+). The electrode has a linear range of 5.0 nM to 0.8 microM with a 10 min accumulation time at open-circuit potential. The sensitivity and detection limit of the proposed sensor are 13 microA/microM and 1.0 nM, respectively. Interference from other heavy metal ions such as Cd(2+), Cu(2+), and Hg(2+) associated with lead analysis can be effectively diminished. The practical application of the proposed sensor has been carried out for determination of trace levels of Pb(2+) in real water samples.