Multifunctional chitosan-cross linked- curcumin-tannic acid biocomposites disrupt quorum sensing and biofilm formation in pathogenic bacteria.

Natural products have a long history of success in treating bacterial infections, making them a promising source for novel antibacterial medications. Curcumin, an essential component of turmeric, has shown potential in treating bacterial infections and in this study, we covalently immobilized curcumin (Cur) onto chitosan (CS) using glutaraldehyde and tannic acid (TA), resulting in the fabrication of novel biocomposites with varying CS/Cur/TA ratios. Comprehensive characterization of these ternary biocomposites was conducted using FTIR, SEM, XPS, and XRD to assess their morphology, functional groups, and chemical structures. The inhibitory efficacy of these novel biocomposites (n = 4) against the growth and viability of Pseudomonas aeruginosa (ATCC27853) and Chromobacterium violaceum (ATCC12472) was evaluated and the most promising composite (C3) was investigated for its impact on quorum sensing (QS) and biofilm formation in these bacteria. Remarkably, this biocomposite significantly disrupted QS circuits and effectively curtailed biofilm formation in the tested pathogens without inducing appreciable toxicity. These findings underscore its potential for future in vivo studies, positioning it as a promising candidate for the development of biofilm disrupting antibacterial agents.

Surfactant modified/mediated thin-layer chromatographic systems for the analysis of amino acids.

This review incorporates a large number of chromatographic systems modified by the surfactants. A large number of solvent systems and stationary phases are summarized in this paper. Three different kinds of surfactants (anionic, cationic, and nonionic) are used as modifiers for stationary phases as well as solvent systems. Surfactants are used at all the three different concentration levels (below, above, and at critical micelle concentration) where surfactants behave differently. Modifications of both stationary phases and solvent systems by surfactants produced a new generation of chromatographic systems. Microemulsion solvent systems are also incorporated in this paper. Microemulsion thin-layer chromatography is a new approach in the field of chromatography.

Shape-directing role of cetyltrimethylammonium bromide in the preparation of silver nanoparticles.

We report a simple chemical reduction method for the synthesis of different colored silver nanoparticles, AgNP, using tyrosine as a reducing agent. Effects of cetyltrimethylammonium bromide, CTAB, and tyrosine concentrations are analyzed by UV-visible measurements and scanning electron microscopy (SEM) to evaluate the mode of AgNP aggregation. The position and shape of the surface resonance plasmon absorption bands strongly depend on the reaction conditions, i.e., [CTAB], [tyrosine], and reaction time. Sub-, post-, and dilution-micellar effects are accountable for the fast and slow nucleation and growth processes. Spectrophotometric measurement also shows that the average size and the polydispersity of AgNP increase with [CTAB] in the solution. CTAB acted as a shape-directing agent.

MnO2 nanostructures of different morphologies from amino acids-MnO4- reactions in aqueous solutions.

In this paper, we describe a simple method for the synthesis of MnO(2) nanostructures (quantum dots) by permanganate oxidations of methionine and cysteine. Upon addition of permanganate to a solution of reductant (methionine and/or cysteine), yellow-brown color species appears within the time of mixing which was stable for several weeks. The UV-vis spectroscopy and transmission electron microscopy (TEM) techniques were used to characterize the nature of color formed. TEM images show that the MnO(2) sol consists of aggregated spherical nonoparticles (size in the range ca

Conductometric studies of micellization of gemini surfactant pentamethylene-1,5-bis(tetradecyldimethylammonium bromide) in water and water-organic solvent mixed media.

The micellization of gemini surfactant pentamethylene-1,5-bis(tetradecyldimethylammonium bromide) (14-5-14) has been investigated in water and water-organic solvent mixed media (organic solvents used: 1,4-dioxane (DO), dimethylformamide (DMF), ethylene glycol (EG)). The conductivity in water and in mixed media (water+organic solvent) as a function of surfactant concentration was measured at different temperatures and the data were used to find critical micelle concentration (cmc) and degree of counterion dissociation (alpha) of the micelle. From the study, it is observed that the micellization tendency of the surfactant decreases in the presence of organic solvents and the increase in the cmc values is comparatively less below 20% (v/v) of organic solvents showing the predominance of water character in the bulk phase at lower compositions of the organic solvents. Thermodynamic parameters were also obtained from the temperature dependence of the cmc values. The standard free energy of micellization was found to be negative in all the cases that became less negative with the increase in the cosolvent content.

(1)H NMR and viscometric studies on cationic gemini surfactants in presence of aromatic acids and salts.

In this paper, we are reporting the influence of addition of aromatic acids (anthranilic and benzoic acid) and their sodium salts on the micellar morphological changes in three cationic gemini surfactant solutions, viz. 5 mM tetramethylene-1,4-bis(N-hexadecyl-N,N-dimethylammonium bromide), 10 mM pentamethylene-1,5-bis(N-hexadecyl-N,N-dimethylammonium bromide), and 10 mM hexamethylene-1,6-bis(N,-hexadecyl-N,N-dimethylammonium bromide). The solubilization site of the counterions (obtained from the additives) near the micellar surface are inferred by 1H NMR. The behavior is explained in the light of binding of counterions to the micelle as well as the nature of the functional group attached to the additive.

Clouding phenomenon and SANS studies on tetra-n-butylammonium dodecylsulfate micellar solutions in the absence and presence of salts.

Clouding phenomenon in aqueous micellar solutions of an anionic surfactant tetra-n-butylammonium dodecylsulfate (TBADS) has been observed as a function of surfactant concentration. Small-angle neutron scattering (SANS) experiments in these systems show clustering of micelles as the temperature approaches the cloud point (CP). The individual micelles and the clusters of micelles coexist at CP. The clustering of micelles depends on the surfactant concentration and temperature. It is proposed that clustering is due to depletion of H-bonded water present around the butyl chains at the micellar surface. This is associated with entropy gain which is considered to be the major thermodynamic factor related to micellar aggregation. The structures (clusters) that emerge depend on the relative lengths of the alkyl chains of the counterion and can be tuned by the temperature.

A 1H NMR study of 1,4-bis(N-hexadecyl-N, N-dimethylammonium)butane dibromide/sodium anthranilate system: spherical to rod-shaped transition.

The effect of addition of sodium anthranilate to 5 mM micellar solutions of gemini surfactant 1,4-bis(N-hexadecyl-N,N-dimethylammonium)butane dibromide is investigated by 1H NMR. The solubilization site of anthranilate anion near the micellar surface is inferred. In the micelles, the An- ions intercalate among the surfactant headgroups producing morphological changes.