Dynamic Electrochemiluminescence Imaging of Single Giant Liposome Opening at Polarized Electrodes

Abstract

In this work, the characterization of release events from liposomes has been addressed quantitatively by an electrochemiluminescence (ECL) imaging strategy. First, ECL reagents ([Ru(bpy)3] 2+ and tripropylamine) have been encapsulated in sealed giant asymmetrical liposomes (100 µm in diameter) made of DOPG/DOPC phospholipids. After sedimentation on an ITO (Indium Tin Oxide) electrode material, the opening of liposomes was then triggered by polarization of the surface. Under these conditions, amperometry, epifluorescence and ECL were combined and synchronized to monitor and image the rupture of giant liposomes through the release and subsequent ECL emission of their redox content. Amperometry allowed the quantification of the content released from single liposomes. The location and status of liposomes (closed or opened) was assessed by epifluorescence. ECL provided imaging the efflux of matter after liposome opening. This original ECL imaging approach favorably compares to strictly photoluminescent or electrochemical techniques and appears adapted to the investigation of membrane rupture / permeation events.

Recent advances in single liposome electrochemistry

“…Recently, the characterization of release events from GUVs has been addressed quantitatively by an electrochemiluminescence (ECL) imaging strategy (Figure 3B) [17]. Similarly to a previous study dealing with probing outside and inside single giant liposomes containing ECL reagents by scanning electrochemical microscopy [53], [Ru(bpy) 3 ] 2+ and tripropylamine are encapsulated in sealed giant asymmetrical liposomes (100 μm in diameter) made of DOPG/DOPC (1,2-dioleoyl-sn-glycero-3-phospho-(1'-rac-glycerol)/1,2-dioleoyl-sn-glycero-3-phosphocholine) phospholipids (Figure 3Bi) [17].…”

“…Recently, the characterization of release events from GUVs has been addressed quantitatively by an electrochemiluminescence (ECL) imaging strategy (Figure 3B) [17]. Similarly to a previous study dealing with probing outside and inside single giant liposomes containing ECL reagents by scanning electrochemical microscopy [53], [Ru(bpy) 3 ] 2+ and tripropylamine are encapsulated in sealed giant asymmetrical liposomes (100 μm in diameter) made of DOPG/DOPC (1,2-dioleoyl-sn-glycero-3-phospho-(1'-rac-glycerol)/1,2-dioleoyl-sn-glycero-3-phosphocholine) phospholipids (Figure 3Bi) [17]. The rupture of giant liposomes during the release of their content at a polarized indium tin oxide (ITO) electrode is monitored and imaged by amperometry, epifluorescence imaging, and ECL imaging, allowing a good spatial and temporal resolution combined to a quantification of the vesicle content (Figure 3Bii and iii) [17].…”

“…Similarly to a previous study dealing with probing outside and inside single giant liposomes containing ECL reagents by scanning electrochemical microscopy [53], [Ru(bpy) 3 ] 2+ and tripropylamine are encapsulated in sealed giant asymmetrical liposomes (100 μm in diameter) made of DOPG/DOPC (1,2-dioleoyl-sn-glycero-3-phospho-(1'-rac-glycerol)/1,2-dioleoyl-sn-glycero-3-phosphocholine) phospholipids (Figure 3Bi) [17]. The rupture of giant liposomes during the release of their content at a polarized indium tin oxide (ITO) electrode is monitored and imaged by amperometry, epifluorescence imaging, and ECL imaging, allowing a good spatial and temporal resolution combined to a quantification of the vesicle content (Figure 3Bii and iii) [17]. ECL is able to provide the image of the efflux of matter (luminophores) after liposome opening and this original imaging approach compares favourably with strictly photoluminescent or electrochemical techniques and appears to be adapted for the investigation of membrane rupture / permeation events [17].…”

“…In the present review, we will focus on the recent advances in single liposome electrochemistry including single-vesicle electrochemical events with the exocytosis process [11][12][13], electrochemical single impacts of synthetic redox liposomes [7,14,15], and the electroanalysis of single giant unilamellar vesicle (GUV) [16,17]. We will present these three different electroanalytical techniques and discuss their current limitations and applications through different recent examples.…”

From glow-sticks to sensors: single-electrode electrochemical detection for paper-based devices

“…25 While the most used luminophores are based on the use of luminol 26 or RuIJbpy) 3 2+ , 27 a variety of metallic complexes and polyaromatic hydrocarbons have also been reported. 25,28 It is also important to consider that ECL has been coupled with traditional electrochemical approaches such as amperometry [29][30][31] as well as bipolar systems. 6,21,26,[32][33][34] While not strictly considered a bipolar system, ECL can also be integrated with much simpler electrochemical systems that use a single, resistive electrode 33 to drive a potential drop across the detection cell.…”