Pratap Bahadur’s research while affiliated with Veer Narmad South Gujarat University and other places

Kosmotropic salts lower the cloud point (CP) in triblock copolymers (BCPs) and exhibit micellization at lower concentrations and temperatures. Our investigation utilizes various physiochemical techniques, including tensiometry, calorimetry, viscosity, spectroscopy, and scattering, to understand the self-assembly phenomenon. Furthermore, by employing photophysical methods, using Coumarin 151 (C-151) dye as a probe, the self-assembly mechanism in the highly hydrophilic F98 in water and NaCl solutions with temperature is reported. Adding NaCl decreases the CP of 10% w/v F98, inducing a significant influence on the micellization behavior. Such an effect is attributed to the dehydration of the PEO blocks of F98. The surface tension (γ) measurements provided an insight into the intermolecular hydrophobic interactions at the air–water interface, indicating the enhanced surface activity in the presence of NaCl as a function of temperature. As the temperature or NaCl concentration increases, the solution flow behavior in terms of relative viscosity $\left({\eta }_{rel}\right)$ notably rises due to the enhanced intermicellar interactions with the continued dehydration of the PEO shell of F98. The salting-out effect of the PEO and PPO blocks of F98 in the presence of NaCl was evaluated by observing changes in bond stretching through Fourier-transform infrared (FT-IR) spectroscopy. Two-dimensional nuclear Overhauser effect spectroscopy (2D-NOESY) revealed insights into the spatial arrangement and dynamic interactions of NaCl binding with the PEO corona (~ 3.0–4.0 ppm) of F98. This binding reduced hydration and significantly altered the micellar dynamics. Additionally, minor shifts observed in the PPO signals (~ 1.0–1.5 ppm) suggested indirect interactions, pointing to changes in the internal environment and segmental dynamics of the micellar core. The spectral behavior is further validated by evaluating optimum descriptors using computational simulations performed with the DFT/B3LYP method within the 3-21G basis set framework, utilizing the Gaussian 5.0.9 software. The absorption spectra under increased NaCl concentration and higher temperatures render the microenvironment around the probe C-151 more hydrophobic, suggesting the formation of H-type aggregation. Additionally, fluorescence excitation spectra indicated a blue shift with increasing NaCl concentration, further supporting H-type aggregation. Here, the average fluorescence lifetime remained constant at ~ 5.4 to ~ 5.7 ns, as observed from fluorescence emission decays. Such consistency in fluorescence lifetime, despite forming H-type and J-type aggregations, indicates that the structural changes around the probe do not significantly affect its excited-state dynamics. It has been observed that the addition of NaCl influences the spectral behavior of F98 due to the dehydration of thermosensitive regions as a function of temperature, likely due to the salting-out effect. Dynamic light scattering (DLS) analysis exhibited temperature-dependent variations in F98 micelle size in the presence of NaCl at varying concentrations, attributed to the screening and salting-out effects, which was further validated from small-angle neutron scattering (SANS) investigation, utilizing a core–shell spherical model. Furthermore, our investigation included a spectral analysis that depicted an improved solubilization assessment of the hydrophobic dye Orange OT expressed in dye loading efficiency (DL%) and encapsulation efficiency (EE%), thereby inferring NaCl to dehydrate the copolymeric micelles due to the salting-out effect. Graphical abstract Scattering and photophysical profile of 10% w/v F98 in water (blank) and with 2 M NaCl at 30 °C.

This study investigates the influence of glucose in inducing the micellar growth/transition in several structurally diverse, longer, and shorter chain polyoxyethylene (POE)‐based nonionic surfactants, commercially known as Kolliphor® HS15 (Solutol), Kolliphor EL®, Akypo®, Brij®‐78, Pluronic® (P103 and F77), Tetronic® (T1304), and Tyloxapol® in aqueous solution environment. It was observed that the addition of glucose induces dehydration of the POE moieties or chains in the tested systems, thereby enhancing the inter‐micellar interactions via hydrogen bonding in the hydrophilic part of the selected surfactants. This dehydration leads to an interesting clouding behavior across all the studied surfactant systems. Also, the dynamic light scattering (DLS) technique accounted for the probable self‐assembly and micellar growth in water and 1 M glucose ( fix ) across various temperatures. Being pharmaceutical excipients, these micellar entities were successfully employed to assay the hydrophobic anticancer drug curcumin (Cur) solubilized, as confirmed by the peak intensity variation from UV–visible spectroscopy. Cur solubilization into glucose‐containing micelles revealed enhanced solubility expressed in terms of drug loading efficiency (DL%), encapsulation efficiency (EE%), partition coefficient (log P), and standard free energy of solubilization (Δ G °), which is due to the glucose‐induced hydrophobicity in the examined nonionic micellar systems.

This study presents the self-assembly of polyethylene oxide (PEO)-block-polypropylene oxide (PPO)-block-polyethylene oxide (PEO)-based block copolymer (BCP) commercially known as Pluronic® P123 in water and in the presence of different copolymeric surfactants (L61, L62, L64, and F68) with varying degree of hydrophilicity, i.e., %EO content. The clouding behavior demonstrates the varied phase transition ranging from solution, blue point (BP), and cloud point (CP). The characteristics of the micelles in the single and mix system are characterized utilizing dynamic light scattering (DLS) and small-angle neutron scattering (SANS) techniques at different temperatures. These scattering approaches provide an insightful information on the micelle size and shape. The size variations in self-assembled micelles designated the micelles to undergo growth/transition in shape from spherical to elongated ellipsoidal as function of temperature. Additionally, the application of these nanoscale micellar aggregates as carriers for delivering the anticancer drug Quercetin (QCT) was undertaken by a thorough quantitative and qualitative analysis to gain valuable insights into the effectiveness of the mix-micellar system as an ideal platform for drug delivery. A comprehensive investigation of drug release kinetics is presented using various kinetic models. The MTT (cytotoxicity assay) assay is used to gauge the effectiveness of the QCT-loaded copolymeric micelles. Graphical abstract Micellar transition of 5% w/v P123 in water and in the presence of copolymeric surfactants as additives at 0.2% weight fraction (fix) at different temperatures

The micellization behavior of conventional cationic surfactant: tetradecyltrimethylammonium bromide (TTAB), and Gemini surfactant (GS): N , N ′‐ditetradecyl‐ N , N , N ′, N ′‐tetramethyl‐ N , N ′ ‐ ethanediyl‐diammonium dibromide (14‐ 2 ‐14) in water and water‐trifluoroethanol (TFE) solvent mixture has been examined using tensiometric and small‐angle neutron scattering (SANS) techniques. Critical micelle concentration (CMC), and various interfacial parameters such as surface tension at CMC (γ CMC ), surface pressure at CMC (π CMC ), maximum surface excess concentration (Γ max ), and minimum area occupied by the head group ( A min ) were evaluated for our examined systems at 303.15 K. It was observed that with the increase in TFE concentration, the CMC of the tested cationic surfactants decreased, thereby favoring the micellization in the presence of the surface‐active TFE. Furthermore, the geometry and aggregation number ( N agg ) of surfactant micelles were inferred using SANS that revealed the decrease in micelle size of cationic surfactants. Additionally, the computational simulation study provided an insight into the molecular interactions in the examined system that validated our experimental findings.

Self-assembly in ethylene oxide (EO)-propylene oxide (PO)-based star-shaped block copolymers (BCPs) in the presence of different kinds of additives is investigated in aqueous solution environment. Commercially available four-armed BCPs namely...

Degradable polymers (both biomacromolecules and several synthetic polymers) for biomedical applications have been promising very much in the recent past due to their low cost, biocompatibility, flexibility, and minimal side effects. Here, we present an overview with updated information on natural and synthetic degradable polymers where a brief account on different polysaccharides, proteins, and synthetic polymers viz. polyesters/polyamino acids/polyanhydrides/polyphosphazenes/polyurethanes relevant to biomedical applications has been provided. The various approaches for the transformation of these polymers by physical/chemical means viz. cross-linking, as polyblends, nanocomposites/hybrid composites, interpenetrating complexes, interpolymer/polyion complexes, functionalization, polymer conjugates, and block and graft copolymers, are described. The degradation mechanism, drug loading profiles, and toxicological aspects of polymeric nanoparticles formed are also defined. Biomedical applications of these degradable polymer-based biomaterials in and as wound dressing/healing, biosensors, drug delivery systems, tissue engineering, and regenerative medicine, etc., are highlighted. In addition, the use of such nano systems to solve current drug delivery problems is briefly reviewed.