Cryo-TEM imaging

Zheng Y, Lin Z, Zakin JL, Talmon Y, Davis HT, Scriven LE (2000) Cryo-TEM imaging the flow induced transition from vesicles to threadlike micelles. J Phys Chem B 104(22) 5263-5271... 

Fig. 2 PICsomes formed from oppositely charged building blocks, (a) Chemical structures of the hybrid polypeptides for PICsomes and scheme of the PICsome preparation, (b) Cryo-TEM image of 100-nm-sized PICsomes (scale bar 50 run). Arrows indicate vesicle walls. Adapted from [70] with permission. Copyright 2010 American Chemical Society...

Figure 6.3 Cryo-TEM image of the nanoemulsions of the water/polyoxyethylene 4 sorbitan monolaurate/[10% EClOin ethyl acetate] system with an O/S ratio of70 30and a water content of 90 wt%.

Fig. 8.6 TEM images of (A) exfoliated sheets of AMP in water (scale bar = 200 nm), and (B) cryo-TEM image of exfoliated AMP organoclay sheets viewed edge-on (scale bar = 50nm).

Fig. 10 (a) Chemical structure of PEG-6-PCL copolymer, (b) CLSM image of PEG-6-PCL polymersomes containing membrane-encapsulated Nile Red (2 mol%) and aqueous entrapped Calcein dyes. Scale bar 5 pm. (c) Cryo-TEM image of PEG-6-PCL polymersomes. Scale bar 100 nm. Reprinted from [228] with permission... 

Fig. 8 Cryo-TEM image of aqueous PB-P2VPQ micelles showing filament network of polyelectrolyte chain bundles. Scale bar is 50 nm. Reprinted with permission from [15]. Copyright (2004) Springer...

Figure 11.16 is a cryo-TEM image of G10 PAMAM dendrimers in water. The cryo technique involves flash freezing of the dendrimer solution as a thin film on a grid and is described elsewhere [20]. Individual dendrimers appear to be organized into an array of single dendrimer thickness. While there are complicating factors due to the sample preparation, the picture is consistent with... 

Morphology. Structural details were visualized by cryo-TEM. Figure 1A is a cryo-TEM image of a sample with an entrapped oligonucleotide-to-lipid ratio of 0.13 mg/mg. It confirms the coexistence of unilamellar liposomes with bi- and multilamellar liposomes. The membranes of the latter are in close contact. The inset of Figure 1A is an expanded view of a multilamellar... 

Figure 14.8 (Left) Primary sequence of peptide MAXI with /8-hairpin promoted intramolecular folding, leading to the reversible formation of self-assembled /8-sheets. (Right) Cryo-TEM image of self-assembled peptide scaffolds. Scale bar = 200 nm. Reprinted from Schneider et al. (2002). Copyright 2002 American Chemical Society.

Fig. 17 (a-d) Cryo-TEM images of diblock (sphere-rod) liposomes comprised of liquid-phase lipid nanorods (white arrows) connected to spherical vesicles. The lipid nanorods are stiff cylindrical micelles with an aspect ratio RilOOO. Their diameter equals the thickness of a lipid bilayer ( 4 nm) and their length reaches up to several micrometers, with a persistence length on the order of millimeters, (c) An inset of B, demonstrating the thickness of the nanorod white arrow heads point out a thickness of rj4 nm (approximate bilayer thickness, identical for the spherical vesicle and the nanorods), (d) Schematic of a MVLBisG2/DOPC sphere-rod diblock liposome. Reprinted with permission from [58]. Copyright 2008 American Chemical Society... 

FIGURE 7.32. Phase diagram of PMOXA-b-PDMS-b-PMOXA in water and Cryo-TEM image of the lamellar phase formed at x = 50. x = polymer fraction in water in % w/w La = lamellar liquid crystalline phase. 

Fig. 5 Cryo-TEM images of polyelectrolyte block copolymer micelles (PEE-PSSH) at a NaCl-concentration of 0.003 mol/1 (a) and 3 mol/1 (b). The core/shell-structure is well visible in Fig. 5b [49]...

Fig. 10 Cryo-TEM images of polyelectrolyte block copolymer micelles (PB-P2VPMeI) with unperturbed spherical corona (a), corona filaments (b), filament networks (c), and micellar strings. The scale bar is 50 nm [56]...

Spherical micelles are not the only association structure that is formed by polyelectrolyte block copolymers. With increasing hydrophobic block length there is a tendency to form block copolymer vesicles. A vesicle formed by PB-P2VP.HC1 is shown in the cryo-TEM image in Fig. 14a. The bilayer structure is clearly resolved which shows that block copolymer vesicles are structurally very similar to lipid vesicles. Vesicles can be also imaged by AFM (Fig. 14b) where they exhibit a characteristic outer rim because the interior solution of the vesicle has evaporated during sample preparation leaving a shape that resembles that of an empty football. Vesicles typically have diameters of 100-300 nm and a bilayer thickness of 10-20 nm. 

Fig. 2 Cryo-TEM images of PS-PNIPA core-shell particles. The sample was kept at 23°C left) and 45°C right) before vitrification [55]. The circle around the core marks the core radius determined by dynamic light scattering (DLS) in solution. The circle around the entire particle gives the hydrodynamic radius of the core-shell particles as determined by DLS...

Fig. 4 Cryo-TEM images of negatively charged microgel particles embedded with different metal nanoparticles (a) with Ag (d = 8.5 1.5nm), (b) with Au (d = 2.0 0.5nm), and (c) with Pd (d = 3.8 0.6nm) nanoparticles. Small black dots are metal nanoparticles. [62]...

Fig. 6 Cryo-TEM images of the silver nanocomposite particles prepared using PS-PNIPA particles with different crosslinker content (a) KPSl-Ag (2.5 mol% BIS), (b) KPS2-Ag (5mol% BIS), and (c) KPS3-Ag (10mol% BIS), (d) Influence of degree of crosslinking on the morphology of silver composite particles [60]...

Diameter of the metal nanoparticles measured from cryo-TEM images bRate constant normalized to the surface of the particles in the system (1)... 

FIGURE 6 Cryo-TEM images of 6-O-CAPRO-P-CD nanospheres (a) and nanocapsules (,b). [(a) Reprinted from E. Memisoglu, A. Bochot, M. en, D. Duchene, and A. A. Hincal, International Journal of Pharmaceutics, 252, 143-153, 2003. Copyright 2003 with permission from Elsevier.)... 

Fig. 13 Cryo-TEM images of (a) 16, (b) I7 (inset magnified view of representative fibers), and (c) schematic representation of the proposed formation of fibers of Ig. The benzenedithiol core of building block 1 is shown in yellow and the peptide chain in blue. Stacks of hexamer are held together by the assembly of the peptide chains into elongated cross-P sheets. (Reproduced from [55])...

Figure 11.8. Illustration of sample preparation for cryo-TEM imaging. Parts (a)-(d) show specimen preparation for sample freezing (e) shows plunge freezing apparatus with temperature and humidity control and ( ) a typical image obtained by cryo-TEM. Copyright 2006 Nestec Etd.

Figure 11.10. Structure of dispersed self-assembly particles. The original cryo-TEM image is shown at the top with schematic representation of the structure below the images. Particles shown are (a) micelles, (b) vesicle, (c) inverted bicontinuous cubic and (d) reverted hexagonal phase particle. Adapted from Sagalowicz et al. 2006a.

The importance of the work on cowpea mosaic virus (GPMV) was that it represented the first time that pseudo-atomic models could be made to describe the exact contact areas of these cryo-TEM image reconstructions. Because the atomic structure of GPMV was known, it was possible to map out the area of contact between the virus and antibody. This technique was used in a number of subsequent cryo-TEM studies and has greatly improved the functional resolution of image reconstruction. 

Fig. 12 Cryo-TEM image of paclitaxol (PTX)-loaded pHPMAmDL-b-PEG micelles. (With permission from...

While the formation of micelles in the solution was expected, cryo-TEM studies proved that the short-chain PDMS-h-PEO diblock copolymers spontaneously form vesicles at low concentrations in aqueous solutions [4], Cryo-TEM images of the studied systems are shown in Fig. 1. 

When the concentration of DMS4-ft-EO 2 was increased to 5 wt%, the cryo-TEM image revealed that the vesicles start to arrange into partially well-ordered multilayers over several hundreds of nanometers, which may mark the beginning of the formation of a well-defined lamellar structure. The thickness of the hydrophobic walls in these multilayers measures 5 nm, which approximates to twice the extended length of the hydrophobic moiety of the polymer. 

Fig. 11 Cryo-TEM image of PMOXA-t>-PDMS-t>-PMOXA vesicles prepared by film swelling in water scale bar 200 nm. Reprinted from [187] Kita-Tokarczyk K, Grumelard J, Haefele T, Meier W. Block copolymer vesicles-using concepts from polymer chemistry to mimic biomembranes. Polymer 46 3540, Copyright (2005), with permission from Elsevier...

In analogy to lipids, amphiphilic block copolymers, i.e., macromolecules composed of at least one hydrophilic and one hydrophobic, covalently linked, polymer chains can form in aqueous solutions vesicles the so-called polymersomes. Generally, in self-assembling copolymer solutions, a rich diversity of morphologies is possible. An overview of the various factors important for vesicle formation, including copolymer architecture, presence of additives, solvent composition, and temperature, is given in [19]. To illustrate polymersome structures we reproduce from [21] on the top row of Fig. 2 cryo-TEM images of vesicles formed by 1.0 wt % aqueous solution of PEO- -PBD (PEO, polyethylene oxide PBD, polybutadiene) diblock copolymer for three different sizes of the PEO and PBD blocks. 

---