The photopolymerization of DC 8,9 PC in microbubbles

The polymerization of diacetylene lipids is a valuable mechanism that can be exploited for various applications ranging from sensor materials to triggered drug delivery. Therefore, mixtures of diacetylene lipid and saturated phospholipids have been extensively studied in liposome vesicles and Langmuir monolayers. The present study investigates the polymerization of 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine (DC8,9PC) in a new assembly, i.e. in a lipid microbubble shell. Lipid microbubbles have a high degree of echogenicity which allows to probe the properties of the mixed lipid monolayer shell using ultrasound spectroscopy. Microbubbles with varying DC8,9PC content in a 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) matrix were characterized using ultrasound transmission spectroscopy, UV–vis absorption spectroscopy and microscopy imaging. The microbubble populations are characterized before and after UV radiation (254 nm), in order to investigate the effect of introducing DC8,9PC into the microbubble shell, and whether diacetylenes can polymerize in this configuration. Microbubbles were found to be more stable when either DSPC or DC8,9PC dominates the composition. UV radiation induced the formation of a diacetylene polymer in all DC8,9PC containing compositions that were investigated, and the polymerization was found to impair the stability of the microbubbles.