Structure of solid-supported lipid membrane probed by noble metal nanoparticle deposition

A Ready-to-Use Metal-Supported Bilayer Lipid Membrane Biosensor for the Detection of Phenol in Water

This work presents a novel metal-supported bilayer lipid membrane (BLM) biosensor built on tyrosinase to quantitate phenol. The detection strategy is based on the enzyme-analyte initial association and not the commonly adopted monitoring of the redox cascade reactions; such an approach has not been proposed in the literature to date and offers many advantages for environmental monitoring with regard to sensitivity, selectivity, reliability and assay simplicity. The phenol sensor developed herein showed good analytical and operational characteristics: the detection limit (signal-to-noise ratio = 3) was 1.24 pg/mL and the sensitivity was 33.45 nA per pg/mL phenol concentration. The shelf life of the tyrosinase sensor was 12 h and the lifetime (in consecutive assays) was 8 h. The sensor was reversible with bathing at pH 8.5 and could be used for eight assay runs in consecutive assays. The validation in real water samples showed that the sensor could reliably detect 2.5 ppb phenol in tap and river water and 6.1 ppb phenol in lake water, without sample pretreatment. The prospects and applicability of the proposed biosensor and the underlying technology are also discussed.

Deposition of metal nanoparticles on phospholipid multilayer membranes modified by gramicidin

A planar dipalmitoyl phosphatidylcholine (DPPC) multilayer phospholipid membrane was structurally modified by introducing a transmembrane protein, gramicidin (up to 25 mol %), to study its effect on the metal nanoparticles deposited on the membrane. Without gramicidin, when 3-nm-thick Ag, Sn, Al, and Au were deposited, the nanoparticles hardly nucleated on the DPPC membrane in rigid gel state (except for Au); however, the gramicidin addition dramatically enhanced the DPPC membrane surface's affinity for metal atoms so that a dense array of metal (Ag, Sn, and Au) or metal-oxide (Al-oxide) nanoparticles was produced on the membrane surface. The particle sizes ranged from 3 to 15 nm depending on the metal and gramicidin concentration, whereas the particle density was strongly dictated by the gramicidin concentration. The proposed method provides a convenient, generally applicable synthesis route for preparing different metal or metal-oxide nanoparticles on a relatively robust biocompatible membrane.