Fig. 5. DNA-Mediated fusion as tool to program the membrane mechanical properties. (a) The fusion between a Laurdan-labelled vesicle (L1) with an unlabelled liposome (U2) of a different composition alters the bilayer structure of L1, as evidenced by the change in Laurdan GP (see ESI†). The fusion product L1–U2 may then able to further fuse with another set of unlabelled liposomes (U3), resulting in a further change in membrane properties. (b) Kinetic traces showing the hardening of 50/25/25 DOPC/DOPE/Chol LUVs (L1soft) after the addition of 50/25/25 DPPC/DOPE/Chol liposomes (U2hard), as suggested by the change in Laurdan GP. This effect was partly reverted through the addition of 50/25/25 DOPC/DOPE/Chol LUVs (U3soft) at time = 90 min. (c) Laurdan GP kinetic traces showing the softening of Laurdan labelled 50/25/25 DPPC/DOPE/Chol LUVs (L1hard) after the addition of 50/25/25 DOPC/DOPE/Chol (U2soft) liposomes. This effect was reverted through the addition of 50/25/25 DPPC/DOPE/Chol LUVs (U3hard) at time = 90 min. L1/U2 ratio was varied as indicated by the legend, while L1/U3 was 1 : 4 in all cases. (d and e) Laurdan emission spectra before and after the 1st and 2nd fusion processes corresponding to the traces shown in b,c) for a 1 : 4 L1 to U2 ratio.
