Atomic force microscopy fibril structure

Stolz, M., Stoffler, D., Aebi, U., and Goldsbury, C. (2000). Monitoring biomolecular interactions by time-lapse atomic force microscopy. / Struct. Biol. 131, 171-180. Sunde, M., Serpell, L. C., Bartlam, M., Fraser, P. E., Pepys, M. B., and Blake, C. C. (1997). Common core structure of amyloid fibrils by synchrotron X-ray diffraction. / Mol. Biol. 273, 729-739. 

The dimension of the resultant structure was visualized by atomic force microscopy (AFM). Indeed, the width of the fibers was reduced compared to that of SAF peptides however, its length was much more heterogeneous. Most fibers were also shown to be shorter than that of previously described coiled coil nanofibers. Fiber shortening could be related to the 1) weak association between sticky-ended coiled coils and 2) salt effects. It was found that sodium chloride and ammonium sulfate have a distinct effect on the fibril lateral aggregation, leading to short fibers in NaCl and long fibers in ammonium sulfate. 

Transmission electron microscopy (TEM) has traditionally been the mainstay of morphological investigations of polyolefins [8], but recent developments in low voltage high-resolution field emission gun scanning electron microscopy (FEG-SEM) [9] and the advent of atomic force microscopy (AFM) and related near-field techniques [10] have challenged its dominance at the length scales of the order of 10 nm, characteristic of both microdeformation (cavitation, fibrils) and structural components of semicrystalline... 

In addition to defining their molecular structures, it is of considerable interest to understand the physical properties of the fibrils and the nature of the forces that lead to their stability. To this end, we have been studying a range of different fibrils by means of experimental approaches originally developed within the rapidly developing field of nanotechnology, such as atomic force microscopy (AFM), in conjunction with computer simulation methods [35]. 

In the course of our studies on the fibril formation in insulin, we have discovered several interesting possibilities to probe the unusual properties of the fibers. In the first place it is possible to follow the formation of the fibers with ultrasound velocimetry. As can be seen from Fig. 5 the decrease in adiabatic compressibility takes place at the same temperature where the P-structures start to form. The dimension of the fibers was verified by atomic force microscopy. 

The structural information about the amyloid fibrils can be obtained by imaging technique such as TEM (Transmission Electron Microscopy), AFM (Atomic Force Microscopy), and X-ray diffraction [28, 29], The analysis of amyloid structure is challenging because of their extremely large size and the difficulty of forming crystallized structures for NMR (Nuclear Magnetic Resonance) spectroscopy. 

Fukuma, T., Mostaert, A. S., Serpell, L. C., and Jarvis, S. P. 2008. Revealing molecular-level surface structure of amyloid fibrils in liquid by means of frequency modulation atomic force microscopy. Nanotechnology 19(38), 384010. 

Knowledge of sizes of ciystallites and non-crystalline domains is very important because it allows clarify the models of super-molecular structure of cellulose, in particular of elementary fibrils of cellulose. There are several methods for measuring the size of the crystallites electron microscopy (EM), atomic force microscopy (AFM),WAXS,etc. 

Atomic force microscopy (AFM) has the necessary resolution to observe nanosized cellulose fibril structures without the need for metal coatings. AFM has been applied to both MFC [7, 25] and cellulose whiskers [41-44] and to generate surface profiles of films cast from cellulose nanocrystals [44—46]. AFM may, however, overestimate the width of the particles [41, 44] due to the tip-broadening effect (the shape of the tip contributes to the recorded image). One way to overcome this problem is to measure the height of the fibrils, which is not subject to tip-broadening artifacts [43]. 

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