Chemical transformations in individual ultrasmall biomimetic containers

Individual phospholipid vesicles, 1 to 5 micrometers in diameter, containin g a single reagent or a complete reaction system, were immobilized with an infrared laser optical trap or by adhesion to modified borosilicate glass s urfaces. Chemical transformations were initiated either by electroporation or by electrofusion, in each case through application of a short (10-micros econd), intense (20 to 50 kilovolts per centimeter) electric pulse delivere d across ultramicroelectrodes. Product formation was monitored by far-field laser fluorescence microscopy. The ultrasmall characteristic of this react ion volume led to rapid diffusional mixing that permits the study of fast c hemical kinetics. This technique is also well suited for the study of react ion dynamics of biological molecules within lipid-enclosed nanoenvironments that mimic cell membranes.