Fluorescence microscopy self-assembly

Kimura, Shirai and coworkers used two chiral dimeric porphyrins 95 and 96 to investigate their self-assembling behavior [162,163]. While incorporation into fibers made of the alkylamide derivatives of (fl,fl)-DACH, 95 formed stable well-resolved fibrous assemblies as visualized by transmission electron microscopy, the fluorescence of which was not quenched by external electron acceptors [162]. However, the induced CD was not detected indicating an inability of 95 to form chirally orientated aggregates under the applied conditions. In contrast, 96 was able to produce optically active inter molecular self-assemblies with an enhanced chiroptical response through the //-oxo bridging in an alkali solution, while intramolecular //-oxo dimer formation was excluded on the basis of steric reasons [163]. 

Fig. 21. Top schematic representation of the subsequent aggregation and gelation processes with the Pt(II) complex. Middle fluorescence microscopy images of the aggregates, and (right) of the gel. Bottom (left and center) SEM micrographs of the self-assembled fibers and TEM micrograph (bottom, right) of the self-assembled gel. Reproduced with the permission of Wiley-VCH (217).

Fig. 15.7. Self-assembly of nanoparticles to patterns of binding sites, (a) The transfer DNA is modified with biotin, so that patterns of specific binding sites are created with SMCP. Fluorescent nanoparticles carrying streptavidin self-assemble to these patterns and form superstructures, (b) The formation of superstructures is observed online with TIRF microscopy, (c) The patterns of binding sites were created with different size and incubated with nanoparticles fluorescing at different wavelengths. Also, the scale bar is formed in this way. The pictures are standard deviations of TIRF microscopy image series recorded at 20 Hz...

The authors also reported on the supramolecular self-assembly from rod—coil—rod triblock copolymers prepared by copolymerization of 5-acetyl-2-aminob-ezophenone with diacetyl functionalized polystyrene with low polydispersity (Scheme 12).110 In contrast to the rod—coil diblock copolymers which exhibit multiple morphologies, the triblock copolymers were found to spontaneously form only microcapsules or spherical vesicles in solution as evidenced by optical polarized, fluorescence optical, and scanning electron microscopies (Figure 33). 

As distinct from sohd supports such as gold or silver, mercury imparts lateral mobihty to hpid monolayers directly self-assembled on its surface, because of its liquid state. This is demonstrated by rapid spontaneous phase separation, with microdomain formation, in a hpid mixture monolayer self-assembled on top of a DPTL thiolipid monolayer tethered to a mercury microelectrode [30]. The presence of microdomains was directly verified from the images of the distal hpid monolayer obtained using two-photon fluorescence lifetime imaging microscopy. 

Studying the interaction forces between molecules and interfaces by means of atomic force microscopy and fluorescence-based technologies on the nanometer scale will provide valuable information on interfaces. Investigating surface functionalization processes with organic and biomolecular moieties, as well as self-assembly at surfaces, will enable insights into the basic properties of the interfaces. 

Herron, J. N., Muller, W., Paudler, M., Riegler, H., Ringsdorf, H., Sici, P. A. (1992). Specific recognition-induced self-assembly of a biotin lipid/streptavidin/Fab fragment triple layer at the air/water interface Ellipsometric and fluorescence microscopy investigations, Langmuir, 8 1413. 

Diblock copolymers can self-assemble into micelles when immersed in a selective solvent of small molecules, or in a matrix comprised of a homopolymer. The micelles are easily detected by techniques such as light scattering (f ) and transmission electron microscopy ( ), but the critical micelle concentration (cmc) may be so small that other techniques are required for its determination. Techniques based on the ability to detect fluorescence from very dilute systems have been used for this purpose ( ). 

Samples, one half coated with SiOa and the other half with Ti02, were used for quantitative surface analysis after each of the siuface treatment steps (cleaning, self-assembly, and polymer and protein adsorption, section 2). These samples exhibit material contrast on a macroscopic scale and are discussed in section 3.1. Micropat-temed surfaces were subjected to identical siuface modification procedures and characterized qualitatively by imaging ToF-SIMS (section 3.2) and fluorescence microscopy (section 3.3) and were used in the cell experiments (section 3.4). In both types of samples, material contrast (on a macroscopic or microscopic scale, Figure la) is converted into contrast with respect to protein adhesion (Figure Ic) via a series of surface modification steps (self-assembly of DDP, adsorption of PLL-g-PEG section 2). 

Figure 1 Chemical structures of the 20 amino acids found in peptides, grouped according to the characteristics of their side chain. Common names and their one letter abbreviations are used to represent the amino acids. Bottom an atomic force microscopy image showing typical morphology of a self-assembling peptide network, macroscopic appearance of a gel for cell cultnre, and appearance of fluorescent-stained gels in a 3D construct.

---