Synthesis and characterization of new periodic mesoporous organosilicas, PMOs, containing benzene and thiophene groups 'within' the channel walls, is presented.

We report a new system of laterally mobile, arrayed vesicles that are encoded with DNA to control tethering to fluid-supported phospholipid bilayers. The motion of individual fluorescently labeled vesicles, specifically bound, are easily visualized by fluorescence video microscopy and observed to collide reversibly on the surface. This system is an ideal model for studying interactions involving membranes, in particular integral membrane proteins.

We recently reported a novel system shown schematically in Figure 1A in which intact lipid vesicles were assembled on a fluidsupported bilayer using oligonucleotide tethers. 1 Functionalized oligonucleotides were covalently attached to the surface of preformed lipid vesicles by incorporating a small fraction of lipids with reactive headgroups during vesicle assembly. Vesicles displaying oligonucleotides were then tethered to a fluid-supported bilayer displaying oligonucleotides of complementary sequence. These tethered vesicles retain their integrity and diffuse parallel to the plane of the supporting bilayer. Encoded arrays of tethered vesicles were created by displaying orthogonal sequences of oligonucleotides on a patterned bilayer surface. 2,3 A major drawback of this method is the requirement for the inclusion of a reactive lipid during the vesicle assembly process. This may be incompatible with vesicles containing proteins (proteoliposomes), the ultimate target of the tethering strategy, due to side reactions with the protein or special features of the proteoliposome assembly. Furthermore, it is desirable to control as much as possible the number of oligonucleotides displayed on the surface and to avoid side reactions such as hydrolysis of the reactive headgroup that leaves unwanted and uncontrolled levels of impurities on the vesicle surface. We now report the synthesis of an amphiphilic oligonucleotide species ( Figure 1B) which is soluble in buffer but inserts cleanly into preformed vesicles and proteoliposomes of varying composition under mild conditions for sequence-specific tethering onto a fluidsupported bilayer ( Figure 1C). This method should be more generally useful not only for synthetic vesicles and proteoliposomes but also for native vesicles and cells.To achieve this goal, we utilized a simple method for functionalization and subsequent modification of oligonucleotides on the 5′-end prior to cleavage from the DNA synthesis column. 4 The terminal dimethoxytrityl (DMT) group was removed and reacted with an iodination reagent, (PhO) 3 PCH 3 I, to render the 5′-end electrophilic. Treatment with a lipid-thiolate 5 followed by deprotection, cleavage, and reverse-phase HPLC purification yielded the desired product ( Figure 1B) (see Supporting Information for details). A complementary set of 24-mer oligonucleotides (sequences A and A′) were synthesized and modified in this way ((C 18 ) 2 -A, (C 18 ) 2 -A′). 7 Egg yolk phosphatidylcholine (PC) vesicles containing Texas Red 1,2-dihexadecanoyl-phosphatidylethanolamine (Texas Red DHPE) (1 mol %) for visualization and unlabeled PC vesicles containing 2 mol % 1,2-dipalmitoyl phosphatidylserine (DPPS) were prepared by extrusion through 100 nm polycarbonate membranes at approximate lipid concentrations of 10 mg/mL. (C 18 ) 2 -A and (C 18 ) 2 -A′ were dissolved in a 50/50 (v/v) mixture of buffer and acetonitrile to 10 µM and added to these preformed Texas Red DHPE and unlabeled PC/DPPS vesicles, respectively, and incubated at 4°C for 4 h. 8 The (C 18 ) 2 -DN...

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The first examples of an oriented periodic mesoporous organosilica (PMO) film, containing a variety of organic groups (ethane, ethene, benzene, thiophene) inside the channel walls, are reported. The mesostructure of the PMO film appears oriented with respect to the surface of the underlying glass substrate. Liquid‐crystal topological defects in the precursor gels are replicated in the resulting PMO film and are evident in polarized optical microscopy images, recorded between crossed‐polarizers, which show fan‐type optical birefringence texture characteristic of the mesostructure.