Phage Langmuir monolayers and Langmuir-Blodgett films

Stable insoluble Langmuir monolayer films composed of Staphylococcus aureus specific lytic bacterio phage were formed at an air-water interface and characterized The phage monolayer was very strong withstanding a surface pressure of similar to 40 mN/m at 20 C The surface pressure-area (Pi-A) Isotherm pos sessed a shoulder at similar to 7 x 10(4) nm(2)/phage particle attributed to a change in phage orientation at the air-water interface from horizontal to vertical capsid down/tail up orientation as surface pressure was increased The Pi-A-dependence was accurately described using the Volmer equation of state assuming horizontal orientation to an air-water interface at low surface pressures with an excluded area per phage particle of 4 6 x 10(4) nm(2) At high pressures phage particles followed the space filling densely packed disks model with a specific area of 8 5x 10(3) nm(2)/phage particle Lytic phage monolayers were transferred onto gold coated silica substrates from the air-water interface at a constant surface pressure of 18 mN/m by Langmuir-Blodgett method then dried and analyzed by scanning electron microscopy (SEM) and ellip sometry Phage specific adsorption (Gamma) in Langmuir-Blodgett (LB) films measured by SEM was consistent with that calculated independently from Pi-A isotherms at the transfer surface pressure of 18 mN/m (Gamma = 23 phage particles/mu m(2)) The 50 nm thickness of phage monolayer measured by ellipsometer agreed well with the horizontal phage average size estimated by SEM Surface properties of phage Langmuir monolayer compare well with other monolayers formed from nano and micro particles at the air-water interface and similar to that of classic amphiphiles I 2 diphytanoyl sn glycero 3 phosphocholine (phos pholipid) and stearic acid (C) 2010 Elsevier B V All rights reserved