engleski

AFM as a Tool in Marine Biophysics

Atomic force microscopy (AFM) is a member of a family of new microscopic techniques that are referred to as scanning-probe microscopies (SPMs). The concept on which all SPMs are based is the generation of images of surfaces by measuring the physical interaction between a sharp tip and the sample rather than by using an incident beam (light or electrons) as in classical microscopy. In general, the AFM studies can be divided in topographical (imaging) and non-topographical (non-imaging) applications. AFM provides real topographic images of the sample surfaces in three dimensions with a vertical resolution as small as 1 Å ; , and with lateral resolution superior to 1 nm. Besides providing topographic data, AFM can also bring other information. In "force mode", the movements of the AFM cantilever can be used to measure forces. A wide range of applications includes measuring intra- and inter-molecular forces, and measuring viscoelastic properties of the samples. Potential applications of AFM in marine biophysics are very broad since this new technique provides a range of new opportunities for viewing and manipulating living and non-living marine specimens under ambient conditions. Examples of AFM images (tapping mode) presented are: marine nano-particles, native marine gel network, miniscule coccolith, marine bacteria (Vibrio harveyi), unicellular marine algae (Dunaliella tertiolecta). The focus of our interest were AFM images of native marine gel. The imaging of native marine gel demonstrate that an important fraction of specimen consists of entangled fibrils. The fibrils look like rigid macromolecules with typical diameter between 1-3 nm and lenght of 0, 1-5 μ m. Althought it is difficult to determine the nature of the fibril based on simple observation, there is strong evidence that the fibrils are mainly polysaccharides since AFM images of polysaccharide molecules have demonstrated similar features^1 as well as chemical and structure analysis of marine gel composition^2. References: 1. McIntire, T. ; Brant, A.D. J. Am. Chem. Soc. 1998, 120, 6909. 2. Kovač, N. ; Faganeli, J. ; Sket. B. ; Bajt, O. Org. Geochem. 1998, 29, 1623.

AFM; AFM imaging of nanostructures; marine nanoparticles; marine biophysics; marine bacteria; marine gel network; nanoplankton; nanostructure

Rad je kao poster prezentiran i na skupu Regional Biophysics Meeting, održanom od 16.-20.03.2005., Zreče, Slovenija ; objavljen u Knjizi sažetaka s programom, Zrinka Abramovič, Iztok Dogša, (ur.) ; Ljubljana, Slovenian Biophysical Society, 2005.