| Abstract
| - The development of chemical reactions in nanospaces is of paramount importance for the development of activenanodevices, particularly in nanofluidics. It has been shown in a previous paper that phospholipid vesicles can beincorporated without spontaneous bilayer rupture into poly-l-glutamic acid/poly(allylamine) (PGA/PAH) multilayeredpolyelectrolyte films. The aim of the present study was to use such a system as an “embedded submicronic reactor”able to trigger precipitation of calcium phosphates within closed spaces through an enzymatic reaction, the enzymealso being encapsulated in the vesicle interior. To this aim, large unilamellar vesicles (LUVs) were produced containingcalcium ions as active ions in the mineralization process, spermine as an activator of crystal growth, and alkalinephosphatase as a catalyst to convert phosphate esters into phosphates. After stabilization by adding a layer of poly-(d-lysine), these vesicles were embedded in a (PGA-PAH)n film. A paranitrophenyl phosphate containing solutionwas then put in contact with this film. It is shown by means of infrared spectroscopy in the attenuated total reflectionmode that, consecutively to this contact, calcium phosphates are growing inside the embedded vesicles. By usingscanning near-field fluorescence microscopy, it is demonstrated that the alkaline phosphatase enzymes are mostprobably located inside the vesicles after their embedding. In addition, atomic force microscopy was used to show,after chemical removal of the organic top layer of the film, that the inorganic platelets produced after the precipitationreaction are localized in volumes of similar size and shape as that of the vesicles into which the phosphate esterhydrolysis and subsequent precipitation reaction did occur.
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