Besides their positive role, microorganisms are related to a number of undesirable effects, including many diseases, biodeterioration and food spoilage, so when their presence is undesired, they must be controlled. Numerous biocides limiting the development of microorganisms have been proposed, however, in this paper the biocidal and inhibitory activity of quaternary ammonium salts (QASs) and their zwitterionic derivatives is addressed. This paper presents the current state of knowledge about the biocidal activity of QAS and their derivatives. Moreover, the known mechanisms of antimicrobial activity and the problem of emerging resistance to QAS are discussed. The latest trends in the study of surfactants and their potential use are also presented.

Surfactants are important ingredients of personal care products and household products. The main characteristic of these compounds is to decrease the surface tension of solvent and resulting many properties such as contact angle, foam properties etc. The coexistence of other ingredients in the product may affect the properties of surfactants. One of the main components contained in almost every personal care and household product is sodium chloride. The main aim of this work was to determine the effect of this salt on some surface and usage properties of cocamidopropyl betaine (CAPB). From our experiments it was shown that the effect of added sodium chloride in the aqueous solutions of CAPB on the properties is the opposite to the one described in the literature for cationic and anionic surfactants, i.e., CMC increases with increasing ionic strength, foam height decreases with increasing salt concentration. Our investigation showed that sodium chloride makes worse the properties of the CAPB solutions examined in this work.

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Sulfobetaines belong to the group of zwitterionic surfactants. They are electroneutral salts, which have in the same molecule, two ionic centers with different charge. Due to the specific structure they exhibit excellent properties such as good solubility in water and detergency. In this paper we present surface properties and adsorption parameters of sulfobetaines in water/air systems. From the adsorption isotherms the CMC value, the surface tension and surface pressure at the CMC as well as the efficiency of adsorption were determined. Physicochemical analyses of the data allowed for the further description of adsorption process. Results showed that sulfobetaines exhibit good surface properties especially low CMC and p20 values. Additionally the antimicrobial activity of sulfobetaines solutions against gram‐positive and gram‐negative bacteria were tested by the well‐diffusion method. MIC values and growth kinetics were determined by microdilution method. Antimicrobial assays demonstrated that sulfobetaines can be good antibacterial agents, but the activity of surfactants strongly depends on alkyl chain length.

Fourteen new sulfobetaines with N-alkylmorpholinium moiety have been synthesized using correspording N-alkylmorpholines and propanesultone or butanesultone. Their interfacial activities in aqueous solution were studied by equilibrium and dynamic surface tension measurements. Surface tension measurements provide information about the surface excess concentration, the minimum area per surfactant molecule, the critical micellar concentration (CMC) and the standard Gibbs energy of adsorption. The adsorption properties of these compounds significantly depend on the length of alkyl chain (the number of carbons). The lowest value of critical micellar concentration is obtained for the compound with the longest carbon chain and decrease with increasing of chain length of compounds considered. The same tendency is observed for effectiveness of adsorption.

Functional biological synthetic composite (BSC) membranes were made using phospholipids, biological membrane proteins and permeable synthetic supports or membranes. Lipid bilayers were formed on porous polycarbonate (PC), polyethylene terephthalate (PETE) and poly (l-lactic acid) (PLLA) membranes and in 10-100 microm laser-drilled pores in a 96-well plastic plate as measured by increased resistance or decreased currents. Bilayers in 50 microm and smaller pores were stable for up to 4 h as measured by resistance changes or a current after gramicidin D reconstitution. Biological membrane transport reconstitution was then carried out. Using vesicles containing Kv1.5 K(+) channels, K(+) currents and decreased resistance were measured across bilayers in 50 microm pores in the plastic plate and PLLA membranes, respectively, which were inhibited by compound B, a Kv1.5 K(+) channel inhibitor. Functional reconstitution of Kv1.5 K(+) channels was successful. Incorporation of membrane proteins in functional form in stable permeable membrane-supported lipid bilayers is a simple technology to create BSC membranes that mimic biological function which is readily adaptable for high throughput screening.

A new method for the preparation of new heterocyclic amine surfactants based on sulfobetaines is proposed. Interfacial activities of the surfactants obtained in aqueous solution were studied by surface tension measurements. The critical micelle concentration, surface excess concentration, minimum area per surfactant molecule, and standard Gibbs energy of adsorption were determined. The adsorption properties of these compounds depend significantly on the alkyl chain length. Alkyl chain length also affects biological properties of the new surfactants, determining the minimum inhibitory concentration and size of inhibited growth zone. The compounds have high antimicrobial activity.

People taking dietary supplements are usually determined to lose weight, supplement nutrition or reduce the risk of illness and negative effects of their state of health. Chromium(III) supplementation influence body composition and mass, glucose and lipid metabolism and it enhance insulin action. This fact could be of general interest because diabetes mellitus is an increasing health problem in many countries. The study describes the effects of high dietary doses of chromium(III) complex with propionic acid [Cr3] (from 100 to 1000 mg Cr · kg(-1) diet) on the organisms of healthy female rats, with special regard to overall nutritional, carbohydrate, lipid and blood biochemical and morphological and haematological indices. The study was carried out on 30 10-week-old female Wistar rats, which were divided into five equal groups (six animals in each): the control group and four groups of tested animals which had free access to the diet supplemented with 100, 200, 500 and 1000 mg Cr · kg(-1) (equivalent of 10, 20, 50 and 100 mg Cr · kg body weight (b.w.) · day(-1)), given as [Cr3O(O2CCH2CH3)6(H2O)3]⋅NO3, also known as Cr3, for 4 weeks. There were no significant differences in body mass gains, feeding efficiency ratio, internal organ masses or blood serum glucose concentrations, except for some changes in the serum triglycerides concentration, which decreased in the rats that received 500 and 1000 mg Cr · kg(-1) diet, as opposed to the group treated with 200 mg Cr · kg(-1) diet. The dietary supplementation of Cr3 for 4 weeks at doses of 100 to 1000 mg Cr · kg(-1) diet did not affect overall nutritional indices and most blood biochemical, morphological and haematological indices.