Interaction, solubilization and location of p-hydroxybenzoic acid and its sodium salt in micelles of moderately hydrophilic PEO-PPO-PEO triblock copolymers

Micelles of ABA type triblock copolymers (where A is polyethylene oxide PEO and B is polypropylene oxide PPO) viz. Pluronic® P103, P104 and P105 (each containing almost the same PPO mol wt. ∼ 3250 g/mol and 30, 40 and 50 wt.% of PEO, respectively) in the presence of p -hydroxybenzoic acid (PHBA) and its sodium salt (Na-PHBA) were examined by viscosity, dynamic light scattering (DLS), small angle neutron scattering (SANS) and NMR. Spherical polymeric micelles (apparent hydrodynamic diameter ∼ 20 nm) in water at 30 ° C grow in the presence of PHBA and transform into prolate-ellipsoidal shape with an increased aggregation number. The micellar transition was favored at higher PHBA concentration, temperature and for copolymers with more hydrophobicity. The PHBA salt, however, increased cloud point and showed only a marginal decrease in aggregation number even at much higher concentrations. The location of PHBA in micelle was elucidated by nuclear Overhauser enhancement spectroscopy (NOESY)

Self-assembly modulation in star block copolymers by amphiphilic diol: A scattering insight

The present study offers a better insight into the alteration in the aggregation characteristics of ethylene oxide-propylene oxide (EO-PO)-based star block copolymers Tetronics® T1304 and T1307 induced by an amphiphilic diol Surfynol® 104 (hereafter C$_{14}$ diol) using scattering (dynamic light scattering and small angle neutron scattering) with complementary physical property measurement viz. solution viscosity and cloud point (CP). It is the hydrophobic interaction that drives C$_{14}$ diol molecules to penetrate inside copolymer micelles resulting in dehydration that lowered the CP and markedly increase in solution viscosity. Quite interestingly, initial lowering in CP is followed by sudden increase at higher level of solubilization. A significant increase in the apparent hydrodynamic diameter (D$_h$) divulges the growth of micelles which is equally supported by SANS measurements. The micellar parameters obtained from SANS analysis for T1304 and T1307 in the presence of C$_{14}$ diol are described. The preferential partitioning of C$_{14}$ diol into the copolymer micelles is the driving force for morphological changes from spherical to unilamellar vesicles. Also, the effect of temperature and NaCl was examined with the aim to observe various micellar transitions. The observed changes are clarified in terms of the hydrophobic interaction of C$_{14}$ diol with Tetronic® micelles and HLB value of copolymers. The perception of C$_{14}$ diol stabilised Tetronic® micelles is anticipated and correlated with optimal parameters obtained from computational simulation approach, providing a clear understanding of the correlation between the molecular orbital energy levels of Tetronic® and C$_{14}$ diol. The present manuscript thus sheds light on C$_{14}$ diol induced dehydration causing the micelle growth for both Tetronics® with varied hydrophobicity. Such hydrophobic diol-induced spherical to vesicular transition is observed for the first time in Tetronic®-diol mixed system

Synthesis and in vitro anti-HIV activity of N-1,3-benzo[d]thiazol-2-yl-2-(2-oxo-2H-chromen-4-yl)acetamide derivatives using MTT method

A series of novel N-1,3-benzo[d]thiazol-2-yl-2-(2-oxo-2H-chromen-4-yl)acetamide derivatives has been synthesized. All the newly synthesized compounds were evaluated for their anti-HIV activity using MTT method. Most of these compounds showed moderate to potent activity against wild-type HIV-1 with an EC50 ranging from >7 EC50 [μg/ml] to <100 EC50 [μg/ml]. Among them, N-1,3-benzo[d]thiazol-2-yl-2-(2-oxo-2H-chromen-4-yl)acetamide 6v was identified as the most promising compound (EC50 = <7 μg/ml). Among all the compounds, three compounds 6m, 6v and 6u have been exhibits potent anti-HIV activity against MT-4 cells

Synthesis and in vitro anti-HIV activity of N-1,3-benzo[d]thiazol-2-yl-2-(2-oxo-2H-chromen-4-yl)acetamide derivatives using MTT method

A series of novel N-1,3-benzo[d]thiazol-2-yl-2-(2-oxo-2H-chromen-4-yl)acetamide derivatives has been synthesized. All the newly synthesized compounds were evaluated for their anti-HIV activity using MTT method. Most of these compounds showed moderate to potent activity against wild-type HIV-1 with an EC(50) ranging from >7 EC(50) [μg/ml] to <100 EC(50) [μg/ml]. Among them, N-1,3-benzo[d]thiazol-2-yl-2-(2-oxo-2H-chromen-4-yl)acetamide 6v was identified as the most promising compound (EC(50)=<7 μg/ml). Among all the compounds, three compounds 6m, 6v and 6u have been exhibits potent anti-HIV activity against MT-4 cells