Emission Color Tuning and White Light Generation from a Trimolecular Cocktail in Cationic Micellar System with Promising Applicability in the Anticounterfeiting Technology.

The development of photoluminescent (PL) systems, displaying multiple stimuli-responsive emission color tuning, has been the pressing priority in the recent times due to their huge role in contemporary lighting and anticounterfeiting technologies. Acknowledging this importance, we present a simple and eco-friendly PL system showing emission color tuning in response to different stimuli, that is, the composition of the system, pH, excitation wavelength, and the temperature with the plus point of getting significantly pure white light emission (WLE). The novel system is fabricated from the aqueous mixture of three organic fluorophores, umbelliferone (UMB), fluorescein (FLU), and Rhodamine-B (RB). By varying the fluorophore composition in the mixture at pH 12, nearly pure WLE with a Commission Internationale d'Eclairage (CIE) 1931 profile of (0.33, 0.33) was obtained at the excitation wavelength of 365 nm, the sustainability of which was ensured by employing the micellar self-assemblies of tetradecyltrimethylammonium bromide (TTAB) molecules. Similar WLE was obtained under mildly acidic conditions (pH 6) but at the excitation wavelength of 330 nm. By proper tuning of pH and the wavelengths of the system to use it as a fluorescent ink, we found a remarkable and highly applicable phenomenon observed for the first time, that is, triple-mode orthogonal emission color tuning with white light ON/OFF switching. We validate the vital applicability of this phenomenon in protecting the authenticity of the document with its hard-to-counterfeit property. The applicability of this phenomenon is also explored by synthesizing PVA-based fluorescent films from the tri-fluorophore mixture. Moreover, the emission color of the PL system was explored lucidly for its temperature dependence owing to the thermal responsiveness of RB emission, where the PL system proves to be a full-color RGB system.

Aggregation and Rheological Behavior of the Lavender Oil-Pluronic P123 Microemulsions in Water-Ethanol Mixed Solvents.

The effect of lavender oil on aggregation characteristics of P123 in aqueous-ethanolic solutions is investigated systematically by DLS, SANS, and rheology. The solubilization capacity of the P123 based formulations toward Lavender oil increased by increasing P123 concentration. The study unveiled the importance of the short chain alcohol-ethanol, as solubilization enhancer. The apparent hydrodynamic radius (Rh) increased significantly with an increase in lavender oil concentration up to maximum oil solubilization capacity of the copolymer at a particular ethanol concentration. DLS measurements on 5, 10, and 15 wt% P123 in the presence of 25% ethanol revealed the presence of large-sized micellar clusters in addition to the oil swollen micelles. The core size (RC), radius of hard sphere (RHS), and aggregation number (N) obtained from SANS profiles showed considerable enhancement with the addition of lavender oil confirming penetration of oil inside the copolymer. Rheological studies showed that viscosity also increased significantly with the addition of lavender oil near the maximum loading limit of the P123 concentration. Quite interestingly, the sol-gel transition temperature displayed a strong dependence on both P123 as well as oil concentration and decreased almost linearly by increasing oil concentration. This study demonstrates the use of a biocompatible and temperature sensitive self-assembled P123 based formulation for lavender oil solubilization that can be beneficial in the cosmetic industry wherein controlled release of fragrances and so forth is demanded.

A novel combined chemical kinetic and trapping method for probing the relationships between chemical reactivity and interfacial H2O, Br- and H+ ion molarities in CTAB/C12E6 mixed micelles.

A delicate balance-of-forces governs the interactions responsible for surfactant self-assembly and chemical reactivity within them. Chemical reactions in micellar media generally occur in the interfacial region of micelles that is a complex mixture of: water, headgroups, counterions, co-ions, acids or bases, organic solvents, and the reactants themselves. We have carried out a detailed study of a complex chemical reaction in mixed CTAB/C12E6 micelles by using the chemical kinetic (CK) and chemical trapping (CT) methods. The results provide a detailed quantitative treatment of the reaction of the anion of the antioxidant t-butylhydroquinone, TBHQ-, with 4-hexadecylbenzenediazonium, 16-ArN2+, within the interfacial region of the mixed micelles in the C12E6 mole fraction range of 0 to 1 at three different total surfactant concentrations. CK experiments showed that this reaction is monophasic in C12E6 micelles, but biphasic in mixed micelles. The results were fully consistent with a complex mechanism in which TBHQ- reacts with 16-ArN2+ to give a transient diazoether intermediate that competitively breaks down into products and or reverts to starting materials. The kinetics are the same in mixed micelles of CTAB/C12E6 (grow) and CTAB/C12E8 (don't grow) showing that the rates only depend on micelle composition, not shape. CT results provided estimates of interfacial molarities of H2O are approximately constant at ca. 39 and Br- decreases from ca. 2.75 to 0.05 moles per liter of interfacial volume as C12E6 mole fraction increases from 0 to 1. Combined CK/CT results provided values for interfacial pH, ranging from ca. 4.25 in cationic micelles to 1.5 in nonionic micelles despite a constant bulk pH of 1.5 and the TBHQ interfacial pKa = 3.8 at all C12E6 molar fractions. In totality, these results yielded an extraordinary amount of quantitative information about the relationships between the chemical reactivity and interfacial compositions of the mixed micelles.

Bergenia stracheyi extract-based hybrid hydrogels of biocompatible polymers with good adhesive, stretching, swelling, self-healing, antibacterial, and antioxidant properties.

An ultra-stretchable, quickly self-healable, adhesive hydrogel with efficient anti-oxidant and anti-bacterial activities makes it potential wound dressing material, particularly in healing skin wounds. However, it is highly challenging to prepare such hydrogels with a facile and efficient material design. Given this, we opine the synthesis of medicinal plant Bergenia stracheyi extract-loaded hybrid hydrogels of biocompatible and biodegradable polymers like Gelatin, Hydroxypropyl cellulose, and Polyethylene glycol with acrylic acid via in situ free radical polymerization reaction. The selected plant extract is rich in phenols, flavonoids, and tannins and found to have important therapeutic benefits such as anti-ulcer, anti-Human Immunodeficiency Virus, anti-inflammatory, and burn wound healing effects. The polyphenolic compounds in the plant extract interacted strongly via hydrogen bonding with -OH, -NH2, -COOH, and C-O-C groups of the macromolecules. The synthesized hydrogels were characterized by fourier transform infrared spectroscopy and rheology. The as-prepared hydrogels demonstrate ideal tissue adhesion, excellent stretchability, good mechanical strength, broad-band anti-bacterial capability, and efficient anti-oxidant properties, in addition to quick self-healing and moderate swelling properties. Thus, the aforementioned properties attract the potential use of these materials in the biomedical field.

pH Changes in the Micelle-Water Interface of Surface-Active Ionic Liquids Dictate the Stability of Encapsulated Curcumin: An Insight Through a Unique Interfacial Reaction between Arenediazonium Ions and t-Butyl Hydroquinone.

The chemical kinetic (CK) method, which involves the reduction of 4-hexadecylbenzenediazonium ions (16-ArN2 +) by antioxidants (in the present case, TBHQ) occurring exclusively at the interface of the association colloids, was employed to establish the changes in the chemical reactivity of anionic surface-active ionic liquids (SAILs) as a function of the concentration and the composition in their mixed states. We used sodium dodecyl sulfate and different SAILs based on the dodecylsulfate surfactant containing 1-alkyl-3-methylimidazolium cations as counterions having a varying alkyl chain length of 4 (bmim), 8 (omim), and 12 (ddmim) carbon atoms. The structural transitions of aggregates of the SAILs from the micellar to vesicular form were observed as a function of concentration in single surfactant systems and as a function of composition in mixed surfactant systems. Results of the reduction kinetics of 16-ArN2 + at the interface of such aggregates, which depends on the acid/base equilibria at the interface, gave an insight into the changes in the interfacial H+ ions with the change in the hydrophobicity of the counterions of SAILs and the morphological changes from micelles to vesicles as a function of concentration or composition. These changes in the interfacial pH correlate very well with the stability of curcumin within these self-assemblies, which exclusively depends on the pH of the medium and highlights the importance of the results obtained from the CK method in selecting the appropriate medium/conditions for the stabilization of the bioactive molecules.

Exploiting self-assembled soft systems based on surfactants, biopolymers and their mixtures for inhibition of Citral degradation under harsh acidic Conditions.

The chemical instability of Citral in acidic conditions is viewed as hurdle to commercialize it in food/beverage industries. We attempted to stabilize citral in various single and mixed surfactant systems at pH 1.0 and temperature 25 °C. The study highlights the importance of amount and density of positive charge of cationic surfactants and oxyethylene content of nonionic surfactants at the interface of self-assembly in inhibiting citral degradation. The hybrid of Chitosan and P123 showed a significant increase in the half-life of citral compared to that in its individual components. The results of the study suggest that it is possible to stabilize citral in strong acidic environs having a pH as low as 1.0 using mixed surfactant or polymer-amphiphile systems with significant positive charge/number of oxyethylene in their single components. Such polymer-surfactant systems formulations if biocompatible/food grade may act as promising media to enhance shelf life of citral.

Immunomodulatory activity of isoflavones isolated from Iris germanica (Iridaceae) on T-lymphocytes and cytokines.

The immunomodulatory activities of two isoflavones, 5,7-dihydroxy-6,4'-dimethoxyisoflavone (irisolidone) (1) and 5,4'-dihydroxy-6,7-methylenedioxyisoflavone (irilone) (2) isolated from Iris germanica (Iridaceae) is reported. Their influence on production of T-lymphocytes (CD4+ and CD8+ cells) and T-cell cytokines, namely Th1: IL-2, IFN-gamma and Th2: IL-4 and IL-5 in a dose-dependent manner was studied by flow cytometric method in Balb/c mice. Oral administration of drugs at doses of 0.1-0.8 mg/kg per oral dose showed 1 to possess stimulatory activity on T-cells and Th1 cytokine production, while as 2 acted as an immunosuppressant for both cells and cytokines. The methylated products of 1 and 2 showed a similar trend to that of their parent compounds but their activity was drastically decreased revealing the importance of free phenolic groups for their immunomodulating activities.

Immunomodulatory effect of bergenin and norbergenin against adjuvant-induced arthritis--a flow cytometric study.

Bergenin (1), a C-glycoside of 4-O-methyl gallic acid, isolated from rhizomes of Bergenia stracheyi (Saxifragaceae) and its O-demethylated derivative norbergenin (2), prepared from 1, are reported to show anti-arthritic activity through possible modulation of Th1/Th2 cytokine balance. Flow cytometric study showed that the oral administration of 1 and 2 at doses of 5, 10, 20, 40 and 80 mg/kg per oral dose inhibit the production of proinflammatory Th1 cytokines (IL-2, IFN-gamma and TNF-alpha) while as potentiate anti-inflammatory Th2 cytokines (IL-4 and IL-5) in the peripheral blood of adjuvant-induced arthritic balb/c mice. This shows the potential Th1/Th2 cytokine balancing activity of 1 and 2 which is strongly correlated with their anti-arthritic activity. At similar dose levels, the effect of 2 was found to be more than that of 1. The oral LD(0) for 1 and 2 was more than 2000 mg/kg body weight of the mice.

Evaluation of antioxidant and antimicrobial activities of Bergenin and its derivatives obtained by chemoenzymatic synthesis.

Bergenin pentacetate (2), a peracetate derivative of biologically active lead compound Bergenin (1) isolated from Bergenia stracheyi was subjected to lipase catalyzed regioselective alcoholysis to obtain 3,4,10,11-tetracetate of Bergenin (3). The free hydroxyl group of 3 was derivatised using higher carboxylic acids to obtain acyl derivatives (4-7). These compounds synthesized via chemoenzymatic route were characterized using 1H NMR, 13C NMR and mass spectral data and evaluated for DPPH radical scavenging, antimicrobial and xanthine oxidase inhibitory activities. The studies revealed that biological activity of Bergenin can be optimized by selective modification of its structure.

New isoflavones from Iris kashmiriana.

Phytochemical investigation of the rhizomes of Iris kashmiriana (Iridaceae) led to the isolation of three isoflavones characterized by 1D and 2D NMR, IR, UV, and MS as 4'-hydroxy-8-methoxy-6,7-methylenedioxyisoflavone (isonigricin, 1), 5,6-dihydroxy-4',7-dimethoxyisoflavone (isoirisolidone, 2), and 5,7-dihydroxy-4',6-dimethoxyisoflavone (irisolidone, 3). Compound 1 is a new isoflavone, while 2 is reported for the first time from a natural source.