Self-assembly ( engl. Self-assembly ) - the process of formation of an ordered supramolecular structure or medium, in which only components (elements) of the original structure, additively constituting or “assembling” as parts of the whole, resulting complex structure, take part in an unchanged form [1] .
Content
Description
Self-assembly refers to typical bottom-up methods for producing nanostructures (nanomaterials). The main task that is involved in its implementation is the need to influence the system parameters in such a way and to set the properties of individual particles in such a way that they are organized to form the desired structure. Self-assembly is at the heart of many supramolecular chemistry processes, where the “instructions” on how to assemble large objects are “encoded” in the structural features of individual molecules. Self- assembly should be distinguished from self-organization , which can be used as a mechanism for creating complex “templates”, processes and structures at a higher hierarchical level of organization than that observed in the original system (see. Fig.). The differences consist in numerous and multivariate interactions of components at low levels, on which there are local, local laws of interaction that are different from the collective laws of behavior of the ordered system itself. Self-organization processes are characterized by interactions of various scales of scale, as well as the existence of restrictions on the degrees of freedom of the system at several different levels of its organization. Thus, the self-assembly process is a simpler phenomenon. Nevertheless, one should not go to extremes and consider, for example, that the process of single crystal growth is self-assembly of atoms (which corresponds, in principle, to the definition), although, for example, self-assembly of larger objects - microspheres of the same size, forming a dense ball packing, which leads to the formation of the so-called photonic crystal (a three-dimensional diffraction grating of microspheres) is a typical example of self-assembly. Self -assembly can include the formation of self-assembled monomolecular layers (for example, thiol molecules on the smooth surface of a gold film), the formation of Langmuir-Blodgett films , layered assembly , etc. [1] . The self-assembly of a number of oligopeptide derivatives in hydrogels is well known with a slight change in the environmental conditions (pH, ionic strength of the solution, temperature, addition of an organic solvent, etc.) [2] . A striking example is the self-assembly of fluorenyl diphenylalanine into nanofibrils, from which the hydrogel is further formed, mainly due to : hydrophobic interactions, the formation of hydrogen bonds and p-p interactions of phenyl rings. Of interest from the point of view of application in medicine is a 3-dimensional macroporous hydrogel as a biodegradable and non-toxic material obtained on the basis of fluorenyl diphenylalanine in one stage and without the use of any crosslinking agents. [3]
Examples
An example of a self-assembly system is micellar solutions .
Notes
- ↑ 1 2 Gudilin Evgeny Alekseevich. Self-assembly "Dictionary of nanotechnological terms" . Rusnano . Date of treatment August 21, 2012. Archived November 24, 2012.
- ↑ AM Smith, RJ Williams, C. Tang, P. Coppo, RF Collins, ML Turner, A. Saiani, RV Ulijn, Adv. Mater. 20 (2008) 37.
- ↑ D. Berillo et al. Formation of macroporous self-assembled hydrogels through cryogelation of Fmoc – Phe – Phe Journal of Colloid and Interface Science 368 (2012) 226–230
Links
- Philosophy of Nanosynthesis // Nanometer, 2007. - (Date of treatment: 13.10.2009).