Liposomes binding

Especially phosphatidylserine (PS) seems to deliver a good liposome binding signal for DCs therefore the influence of PS content on the binding to DCs was studied in greater detail in a second set of experiments (data not shown in figure 2). At a PS content of 50% in the liposomes, about 80% of... 

Integrin receptor-binding peptides have been used to enhance liposome binding, uptake, and expression (25,47 9). The inclusion of an 0(5pi integrin-targeted peptide into a liposomal complex enhanced transfection efficiency four- to five-fold in Jurkat cells and 10- to 13-fold in TF-1 cells (48). Confocal and electron microscopy revealed that the mechanism of cell entry conferred by RGD peptides on liposomes is predominantly by clathrin-coated endocytosis rather than by phagocytosis (50). 

Fricks CE, Hogle JM. Cell-induced conformational change in poliovirus Extemalization of the amino terminus of VP1 is responsible for liposome binding. J Virol 1990 64 1934-1945. 

Fig. 4.6 (A and B) Dependence of the drug-induced reduction of the transition temperature (A 7",) on the amount of chlorphentermine and clofibric acid added. The dissociation equilibrium of the drugs was shifted to the indicated forms by adjusting the pH of the liposome suspension to pH 6 and over pH 9 respectively (A). Dose-effect curves of the uncharged forms (pH 10 and pH 4.5, respectively. Dotted line indicates drug amounts at which morphologic alterations occurred in the liposome suspension (B). (Reprinted from Fig. 2 of ref. 96 with permission from Elsevier Science). (C) Liposomal binding of chlorphentermine and clofibric acid depending on the total amount of drug added to the liposome suspension (mean values of triplicate determinations). Maximum deviation from the mean was 10% of the mean. (Reprinted from Fig. 3 of ref. 96 with permission from Elsevier Science)...

Quantitative investigation of recognition of this pair of liposomes was performed with isothermal titration microcalorimetry (ITC). It has been found that one-to-one binding between adenine and barbituric acid in the lipid/water/lipid interface occurs. However at T= 58°C, above the main lipid phase transition, the situation is different and no liposomal binding is detected. This is mainly due to the molecular disorder within the bilayer (liquid-disordered/liquid ordered phase coexistence) that limits the capacity of complementary moieties to bind, due to the weakening of the hydrogen bonds at these high temperatures. 

Free folic acid is added for competitive inhibition of folate targeted liposome binding to the folate receptor. Consequently, receptor-mediated uptake of these liposomes will also be inhibited (5). 

Fig. 2. Intracellular localization of TAT-liposomes. OVCAR-3 cells are incubated with 150 nmol of double fluorescently labelled TAT-liposomes for 1 h and subsequently incubated for 1 h (a) or 23 h (b) in liposomes-free medium. Thirty minutes before visualization the endocytic pathway is labelled with Lysotracker Red. Live cell imaging is performed with confocal laser scanning microscopy. Double labelled liposomes are used to study the integrity of the liposome during the uptake process co-localization of both liposomal labels would indicate that the liposomes are intact. 1 h both liposomal labels are localized at the plasma membrane, which represent intact cell-bound TAT-liposomes. The electronically merged image clearly shows lack of co-localization with the endocytic pathway marker, Lysotracker Red. This opposite to the 24 h incubation, both liposomal labels can be seen intracellularly in a punctuate pattern. In the electronically merged image, co-localization with Lysotracker Red is clearly visible. This indicates that the TAT-peptide modified liposomes bind to the plasma membrane and after internalization are present in endocytic vesicles. Therefore, we conclude that the liposomes are internalized by endocytosis. (Reproduced from (12) with permission from Elsevier Science)...

Reporter probe-tagged liposomes bind at control zone... 

Figure 10.1. General scheme for detection of analytes by PDA liposomes. Binding of the analyte to the receptor on the liposome surface induces structural perturbations in the PDA structure, leading to changes in color.

The simultaneous measurements of SPR and electrochemical impedance were carried out using a flow injection analysis (FIA) cell by Bart et al. [5]. The FIA system was tested for interferon-y detection using liposome bounded to the secondary antibody to increase the amount of mass for SPR detection. Liposome binding did not yield an impedance shift, but the different concentrations of interferon caused an increase in the impedance signal. In this way, it was possible to use the impedance-SPR measurements in this system. This immunosensor indicates the usefulness of the FIA cell for investigations of the ESPR method as a biosensor development. 

This approach can also be used to identify novel or unexpected proteins that contribute to cytoskeletal function on membranes. We have successfully isolated and identified individual protein bands from the SDS-PAGE gels and identified them using mass spectrometry (Chen et al., 2004). This has been particularly feasible with the vesicle fractions and liposome binding assays where the background from resident Golgi proteins is greatly reduced or absent (Fig. 3). 

Weinstein JN, Blumenthal R, Sharrow SO et al (1978) Antibody-mediated targeting of liposomes. Binding to lymphocytes does not ensure incorporation of vesicle contents into the cells. Biochim Biophys Acta 509 272-288... 

Minnes R, Weitman H, Lee HJ, Goran SM, Ehrenberg B (2006) Enhanced acidity, photophysical properties and liposome binding of perfluoroalkylated phthalocyanines lacking C-H bonds. Photochem Photobiol 82 593-599... 

Glycolipids are highly suited to be integrated into liposomes for testing glycan-dependent liposome aggregation and liposome binding to surfaces. No chemical... 

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