Browsing by Author "Anchev B.A."
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Item ANTIMICROBIAL ACTIVITIES OF AMPHIPHILIC DERIVATIVES OF α-AMINO ACIDS(2023-01-01) Kondova V.K.; Tsekova D.S.; Anchev B.A.; Miravet J.F.; Angulo-Pachón C.Antimicrobial products are very important to the health of the society. The increasing resistance of some bacteria to existing antimicrobials require searching of new active substances with antimicrobial activities. This review is devoted to the newly synthesised amphiphilic derivatives of proteinogenic a-amino acids and study of their antimicrobial properties. For this purpose, classification of the basis of both - head charge and type of the amino acid is presented with focus on the cationic representatives as possessing well-expressed antimicrobial activities. Data about representatives of amphiphilic alpha-amino acid derivatives with proven antimicrobial activity has been summarised, presented in tables and compared. Results obtained up to now show that arginine derivatives are the most promising, but also gemini derivatives of lysine and arginine amphiphiles have higher antimicrobial activity then monomeric ones. Even though these compounds have lower toxicity thаn conventional surfactants, they are still more toxic than accepted for drug formulations, so to be used in terms of antibiotics. Characteristics of the newly designed alpha-amino acid amphiphilic derivatives should be improved before their antimicrobial potential becomes practically applicable.Item Monolayer formed by l-Asp-based gemini surfactants self-assembled in 1D nanostructures(2019-01-01) Anchev B.A.; Tsekova D.S.; Mircheva K.M.; Grozev N.A.Herein, studies on the surface activities of newly synthesized l-Asp-based gemini surfactants, both nonionic and anionic, are presented. Conductometry, tensiometry, and the Langmuir-Blodgett (LB) film technique were applied for this purpose. π-A isotherms were obtained with a Langmuir trough and Wilhelmy balance. The structures of the monolayers assembled at the air/water interface and those deposited as LB films were studied via Brewster angle microscopy (BAM) and atomic force microscopy (AFM). The 2D films formed by the anion-active compounds show a well-known pattern of a monolayer film, whereas the nonionogenic amphiphiles have been found to be 1D structures with nano-widths and micro-lengths that align with each other during the process of compression; this is the first study where the organization of 1D fibrils in 2D films during compression is reported. The scanning electron microscopy (SEM) study reveals that 1D nanostructure formation is an intrinsic tendency of these molecules as not only nonionogenic surfactants, but also the anion active representatives have been constructed in the solid state by fibrillary structures.