The energy transfer based fluorescent approach to detect the formation of silica supported phosphatidylcholine and phosphatidylserine containing bilayers

• Silica coated Tb(III) complexes are templates for adsorption of phosphatidylcholine.
• Energy transfer from Tb(III) to dyes senses adsorption of phosphatidylcholine onto silica.
• Phosphatidylserine–phosphatidylcholine mixtures of various content are adsorbed onto silica.
• Enrichment by phosphatidylserine enhances binding of copper ions by adsorbed bilayers.
• Energy transfer from Tb(III) to Cu(II) senses enrichment of bilayers by phosphatidylserine.

The work introduces the quenching of silica coated Tb(III) complexes by merocyanine 540 (MC540) and copper ions as a tool to reveal the adsorption of phosphatidylcholine (PC) and phosphatidylserine (PS) at various PS:PC ratio onto silica nanoparticles doped with Tb(III) complex. The binding of MC540 with PC-based bilayers and copper ions with PS-based ones are the basis of their use as organic and inorganic probes to sense PS:PC ratio in silica supported mixed bilayers. The enrichment of mixed bilayers by PS results in the displacement of MC540 anions, while it enhances the binding with copper ions. The displacement or binding of probe ions results in the diverse luminescence response of Tb(III)-centred luminescence. The reestablishment of the steady state and time resolved luminescence is observed, when MC540 anions are applied as probes. The use of copper ions as probes results in the opposite quenching effect. The developed route enables to discriminate the formation of the phospholipids bilayers onto silica surface from those in the bulk of solution under various concentration conditions.

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