Langmuir-Schaefer transfer

Sample Preparation Langmuir-Blodgett, Langmuir Schaefer Transfer, and UV Photopolymerization... 

Methodologies for the fabrication of biomimetic membranes vary somewhat from one biomimetic membrane to another. However, a number of experimental procedures for the formation of lipid monolayers and bilayers on solid supports are common to several biomimetic membranes. The most popular procedures are vesicle fusion, Langmuir-Blodgett and Langmuir-Schaefer transfers, and rapid solvent exchange. The formation of lipid monolayers and bilayers on gold and... 

Fig. 2 The construction of a polymer-cushioned lipid bilayer membrane. (A) Architecture constructed in a sequential way first, onto the functionalized substrate a polymer layer (cushion) is deposited by adsorption from solution and covalent binding, followed by the (partial) covalent attachment of a lipid monolayer containing some anchor lipids as reactive elements (B) able to couple the whole monolayer to the polymer cushion. (C) Alternatively, a lipopolymer monolayer, organized, e.g., at the water-air interface can be co-spread with regular low-mass amphiphiles and then transferred as a mixed monolayer onto a solid support, prefunctionalized with reactive groups, able to bind covalently to the polymer chains of the lipopolymer molecules, (B). (D) By a fusion step (or a Langmuir Schaefer transfer) the distal lipid monolayer completes the polymer-tethered membrane architecture...

Langmuir-Schaefer transfer A Langmuir film transferred to a substrate by moving it parallel to the film. 

The other method of monolayer transfer from the air/water interface onto solid substrates is illustrated in Figure 2. This method is called the Langmuir-Schaefer technique, or horizontal lift. It was developed in 1938 by I. Langmuir and V. Schaefer for deposition of protein layers. Prepared substrate horizontally touches the monolayer, and the layer transfers itself onto the substrate surface. The method is often used for the deposition of rigid monolayers and for protein monolayers, hi both cases the apphcation of the Lang-muir-Blodgett method produces defective films. 

Fig. 8 shows an AFM image of a DPPC bilayer formed using a combination of the LB technique and the Langmuir-Schaefer (LS) method [18]. In this approach, the first monolayer is deposited onto the substrate using the LB dipping technique. The second monolayer is deposited on the first using the LS approach where the substrate is positioned parallel with the air-water interface and transferred through the interface. This results in a Y-type lipid bilayer supported on a substrate. 

Another procedure for transferring monolayers is the Langmuir-Schaefer (LS) method, in which the solid support is moved downward until it horizontally touches the monolayer at the liquid interface. After contacting for a few or a few tens of seconds the solid substrate is withdrawn or pushed down into the liquid subphase. The LS method is far less popular than the LB method but it may be preferred for use with monolayers that are rather rigid. 

In the Langmuir-Schaefer method, a flat substrate is placed horizontally onto a compressed monolayer on the liquid-air interface. When the substrate is lifted horizontally and separated from the water subphase, the monolayer is transferred onto the substrate (Figure 4). The method is useful to transfer viscous films as well as monolayers of lipids and proteins. ... 

The grafting-to method is based on the synthesis of polymer chains in solution, which are then physically or covalently bound to a solid surface. Various grafting-to methods have been used (i) spreading and fusion of micelles or vesicles on solid supports, (ii) transfer of monolayers (Langmuir-Blodgett (LB) and Langmuir-Schaefer (LS)), and (iii) LbL methods. ... 

The second way of preparing L-B monolayer structures, the horizontal lifting method, was introduced by Langmuir and Schaefer. In this method, a compressed monolayer first is formed at the water-air interface, and a flat substrate is then placed horizontally on the monolayer film. When the substrate is lifted and separated from the water surface, the monolayer is transferred onto the substrate, as depicted in Fig. 15(d). 

Another way of transferring monolayers to solid substrates is the horizontal dipping method, first applied by Langmuir and Schaefer to deposit proteins onto... 

Langmuir and Schaefer (13) studied the activity of films of unfolded urease transferred on metal plates by following the rate of decomposi> tion of urea. Their final conclusion was that only 5 per cent of the original activity was exhibited by the film. Furthermore, if the film was left standing at the water interphase for 15 minutes before transfer, only 2 per cent of the original activity remained. This points strongly towards complete inactivation of the urease by unfolding. 

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