Publications by authors named "Vinod Aswal"

This work reports the nanoscale micellar formation in single and mixed surfactant systems by combining an amphiphilic graft copolymer, Soluplus® (primary surfactant), blended with other polyoxyethylene (POE)-based nonionic surfactants such as Kolliphor® HS15, Kolliphor® EL, Tween-80, TPGS®, and Pluronics® P123 in an aqueous solution environment. The solution behaviour of these surfactants as a single system were analyzed in a wide range of surfactant concentrations and temperatures. Rheological measurements revealed distinct solution behaviour in the case of Soluplus®, ranging from low-viscosity () and fluid-like behavior at ≤20% w/v to a highly viscous state at ≥90% w/v, where the loss modulus ('') exceeded the storage modulus (').

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Surface-active peptides (SAPs) typically mimic conventional surfactants by featuring long non-polar (hydrophobic) peptide tails and short polar (hydrophilic) heads consisting of a single amino acid or short peptide. However, reverse-structure SAPs-with a long hydrophilic tail and short hydrophobic head-remain largely unexplored. If developed, such SAPs could form micelles with a larger hydrophilic area and a smaller hydrophobic core, leading to novel self-assembled structures.

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A series of amphiphilic polyurethanes were synthesized by condensation polymerization between hexyl-diisocyanate and Boc-protected serinol in the presence of a chain-stopper R-OH ( = short hydrocarbon chain). Deprotection of the Boc group produced amphiphilic polymers with pendant amine groups, which, at pH ∼5, adopted an intrachain H-bonding-stabilized pleated structure. Hierarchical assembly of such folded chains produced unilamellar vesicles with excellent surface display of the amine groups.

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Imidazolium-based surface active ionic liquids (SAILs) appended with a hydroxyethyl moiety at a cationic headgroup at a position opposite to an alkyl chain ([CImOH][Br] and [CImOH][Br]) and alkyl chain functionalized with amide ([CAImOH][Br]) and ester ([CEImOH][Br]) groups have been synthesized. Different techniques, i.e.

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Phase behaviour and wetting properties of negatively charged silica nanosuspensions are influenced strongly by polyethylene oxide-polypropylene oxide-polyethylene oxide based non-ionic surfactants, known popularly as Pluronics. These triblock copolymers are adsorbed at silica nanoparticle surfaces and impart inter-particle attraction driven re-entrant liquid-liquid phase separations in silica nanosuspensions. The association characteristics of Pluronics at silica surfaces that lead to such behaviours are, however, not clearly understood yet.

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The interaction between proteins and surfactants has gained significant research interest due to its extensive applications across various fields, including the food industry, cosmetics, and medicine. Surfactants are known to unfold the proteins, where there are extensive models describing the basic mechanism of such unfolding and the resultant structure formed across micro-to-macro length scales. These models grounded on extensive experimental and simulation studies aim to predict the interaction dynamics based on several physicochemical parameters, such as surfactant properties (, ionic character and tail length), protein characteristics (, charge and isoelectric point), and solution conditions (, pH, ionic strength, and temperature).

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This study explores the atomic-level interactions of different poly(ethylene oxide) (EO)-poly(propylene oxide) (PO)-based block copolymers (BCPs), commercially known as Pluronics, with varying hydrophilicity that influences the solution behavior within Pluronic P123 micelles as a mixed system. The critical insights into the thermoresponsiveness of P123 in the presence of different Pluronics with increasing %EO content (L61, L62, L64, and F68) is hypothesized to modulate the hydrophobic interactions, leading to distinct solution textures such as clear solution (sol), blue point (BP), and cloud point (CP). The solution relative viscosity (η) and rheological analysis will depict the dynamic flow behavior and expose the viscoelastic properties of the blended system.

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Polyoxometalates (POMs) are composed of nanometric metal-oxide anions and have rich solution chemistry. In this class, Keggin POMs have been identified as the most influential inorganic additives for aqueous nonionic soft matter systems. POMs being at the borderline of classical ions and charged colloids possess fascinating solution properties; the present work aims to delve deeper into the interactions between nanoions and nonionic soft matters from a spectroscopic point of view.

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Self-assembly of amino acids and short-peptide derivatives attracted significant curiosity worldwide due to their unique self-assembly process and wide variety of applications. Amino acid is considered one of the important synthons in supramolecular chemistry. Self-assembly processes and applications of unfunctionalized native amino acids have been less reported in the literature.

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Introduction of non-DLVO forces by nonionic surfactants brings about fascinating changes in the phase behavior of silica nanosuspensions. We show here that alterations in the interaction and wetting properties of negatively charged silica nanoparticles (Ludox® LS) in the presence of polyethylene oxide-polypropylene oxide-polyethylene oxide-based triblock copolymers called Pluronics lead to the formation of stable o/w Pickering emulsions and interparticle attraction-induced thermoresponsive liquid-liquid phase separations. The results make interesting comparisons with those reported for Ludox® TM nanosuspensions comprising larger silica nanoparticles.

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Article Synopsis
  • The study compares the DNA compaction efficiency of two single-head-double-tailed surfactants (DDAB16 and DDAB18) and one triple-head-double-tailed surfactant (MQAS12), finding DDAB18 to be the most efficient and MQAS12 the least.
  • Hybrid materials combining surfactants with silica nanoparticles show improved compaction efficiency due to cooperative binding, allowing for effective DNA compaction at lower surfactant concentrations, which reduces cytotoxicity.
  • The research indicates that the hydrophobicity and structural characteristics of surfactants and nanoparticles significantly influence DNA compaction, supporting the potential design of safe and efficient non-viral vectors for biomedical applications.
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Hybrid nanoparticles formed by Silica (SiO) coated with cationic gemini surfactants with variable hydroxyl group substituted spacers, 12-4(OH)-12,2Br and 12-4(OH)-12,2Br have shown a great extent of compaction of calf thymus DNA (ct-DNA) compared to conventional counterpart cationic surfactant, dodecyl trimethylammonium bromide (DTAB). Study shows not only the hydrophobicity of the spacer but also the hydrogen bonding interactions between the hydroxyl group substituted spacer and DNA have a great role in DNA compaction. 12-4(OH)-12,2Br is more efficient in compacting ct-DNA compared to 12-4(OH)-12,2Br due to the stronger binding of the former with ct-DNA than the latter.

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Fundamental investigations into the photophysical properties and microenvironmental features of pluronic-zwitterionic surfactant mixed assemblies are essential for advancing our understanding of molecular interactions at the nanoscale, setting the stage for innovative solutions in drug delivery, diagnostics, and other applications of pluronic-zwitterionic surfactant assemblies. This investigation explores the intricate photophysics of pluronic-zwitterionic surfactant mixed assemblies, utilizing the twisted intramolecular charge transfer state forming styryl dye trans-2-[(4-dimethylamino) styryl] benzothiazole as a probe. By comparing the behaviors of two distinct poly(ethylene oxide)--poly(propylene oxide)--poly(ethylene oxide) block copolymers with block composition of (PEO)(PPO)-(PEO) [F108] and (PEO)-(PPO)-(PEO) [F127] at concentrations of 5 and 10 wt %, this study systematically examines the impact of the addition of zwitterionic surfactants.

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An interesting evolution of the re-entrant interaction has been observed in an anionic silica nanoparticle (NP)-block copolymer (P85) dispersion due to mutually competing effects of temperature and polymer concentration. It has been demonstrated that a rise in the temperature leads to an evolution of attraction in the system, which interestingly diminishes on increasing the polymer concentration. Consequently, the system exhibits a re-entrant transition from repulsive to attractive and back to repulsive at a given temperature but with respect to the increasing polymer concentration, within a selected region of concentration and temperature.

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The effects of two ionic liquids (ILs), 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim]BF) and 1-butyl-1-methyl pyrrolidinium tetrafluoroborate ([bmp]BF), on a mixture of phospholipids (PLs) 1,2-dipalmitoyl--glycero-3-phosphatidylcholine (DPPC), 1,2-dipalmitoyl--glycero-3-phosphoethanolamine (DPPE), and 1,2-dipalmitoyl--glycero-3-phosphoglycerol (DPPG) (6:3:1, M/M/M, 70% PL) in combination with 30 mol % cholesterol (CHOL) were investigated in the form of a solvent-spread monolayer and bilayer (vesicle). Surface pressure (π)-area () isotherm studies, using a Langmuir surface balance, revealed the formation of an expanded monolayer, while the cationic moiety of the IL molecules could electrostatically and hydrophobically bind to the PLs on the palisade layer. Turbidity, dynamic light scattering (size, ζ-potential, and polydispersity index), electron microscopy, small-angle X-ray/neutron scattering, fluorescence spectroscopy, and differential scanning calorimetric studies were carried out to evaluate the effects of IL on the structural organization of bilayer in the vesicles.

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The addition of a surfactant and/or an increase in temperature disrupt the native structure of proteins, where high temperature further results in protein gelation. However, in a mixed protein-surfactant system, surfactant concentration and temperature have been observed to exhibit both mutually associative and counter-balancing effects towards heat-induced gelation of protein-surfactant dispersion. This study is conducted on globular bovine serum albumin (BSA) protein and cationic surfactant dodecyl trimethyl ammonium bromide (DTAB), which interact strongly owing to their oppositely charged nature.

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Extensive research has been carried out to investigate the stability and function of human serum albumin (HSA) when exposed to surface-active ionic liquids (SAILs) with different head groups (imidazolium, morpholinium, and pyridinium) and alkyl chain lengths (ranging from decyl to tetradecyl). Analysis of the protein fluorescence spectra indicates noticeable changes in the secondary structure of HSA with varying concentrations of all SAILs tested. Helicity calculations based on the Fourier transform infrared (FTIR) data show that HSA becomes more organized at the micellar concentration of SAILs, leading to an increased protein activity at this level.

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The micellization of choline-based anionic surface-active ionic liquids (SAILs) having lauroyl sarcosinate [Sar], dodecylsulfate [DS], and deoxycholate [Doc] as counter-ions was investigated in an aqueous medium. Density functional theory (DFT) was employed to investigate the net interactional energy (), extent of non-covalent interactions, and band gap of the choline-based SAILs. The critical micelle concentration (cmc) along with various parameters related to the surface adsorption, counter-ion binding (), and polarity of the cores of the micelles were deduced employing surface tension measurements, conductometric titrations and fluorescence spectroscopy, respectively.

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The constraints associated with current cancer therapies have inspired scientists to develop advanced, precise, and safe drug delivery methods. These delivery systems boost treatment effectiveness, minimize harm to healthy cells, and combat cancer recurrence. To design advanced drug delivery vehicle with these character, in the present manuscript, we have designed a self-healing and injectable hybrid hydrogel through synergistically interacting metal organic framework, CuBTC with the poly(vinyl alcohol) (PVA).

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The present study investigated the feasibility of fabricating self-assembled liposomes, LeciPlex®, a phospholipid-based vesicular nanocarrier using cationic, anionic, and nonionic stabilizers. The phospholipid investigated was soy phosphatidylcholine and the nano-precipitation method based on solvent diffusion was applied as the fabrication technique of liposomes in this study. The effects of various formulation variables, such as lipid and stabilizer concentration, total solid concentration, and solvent type on the self-assembly of vesicles were studied for physical characterization including particle size analysis, differential scanning calorimetry, viscosity, optical transmittance, transmission electron microscopy, and small angle neutron scattering.

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Transdermal drug delivery systems (TDDS) are a promising and innovative approach for breast cancer treatment, offering advantages such as noninvasiveness, potential for localized and prolonged drug delivery while minimizing systemic side effects through avoiding first-pass metabolism. Utilizing the distinctive characteristics of hydrogels, such as their biocompatibility, versatility, and higher drug loading capabilities, in the present work, we prepared ionic hydrogels through synergistic interaction between ionic liquids (ILs), choline alanine ([Cho][Ala]), and choline proline ([Cho][Pro]) with oleic acid (OA). ILs used in the study are biocompatible and enhance the solubility of 5-fluorouracil (5-FU), whereas OA is a known chemical penetration enhancer.

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Iron oxyhydroxide, a natural nanophase of iron found in the environment, plays a crucial role in regulating surface and groundwater composition. Recent research proposes that within the nonclassical prenucleation cluster growth model, subnanometer-sized clusters (olation clusters/Fe δ-Keggin oxolation clusters) might act as the prenucleation clusters (PNCs) of ferrihydrite or iron oxyhydroxide solid phase. However, these clusters are difficult to characterize as they are only observable momentarily in low-pH, high-Fe concentration solutions before agglomerating into extended solids, keeping the controversy over the true nature of the PNCs alive.

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The rise of multidrug-resistant bacterial infections and the dwindling supply of newly approved antibiotics have emerged as a grave threat to public health. Toward the ever-growing necessity of the development of novel antimicrobial agents, herein, we synthesized a series of cationic amphiphilic biocides featuring two cationic headgroups separated by different hydrophobic spacers, accompanied by the inclusion of two lipophilic tails through cleavable ester functionality. The detailed aggregation properties offered by these biocides were investigated by small-angle neutron scattering (SANS) and conductivity.

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Self-assembly of ethylene oxide (EO)-propylene oxide (PO)-based star-shaped block copolymers (BCPs) in the presence of different kinds of additives is investigated in an aqueous solution environment. Commercially available four-armed BCPs, namely Tetronics® (normal: T904 with EO as the terminal end block; and reverse: T90R4 with PO as the terminal end block), each with 40%EO, are used. The effect of various additives such as electrolytes (NaCl and NaSO), nonelectrolyte polyols (glucose and sorbitol), and ionic surfactants ( anionic-sodium dodecyl sulfate (SDS), cationic-dodecyltrimethylammonium bromide (DTAB) and zwitterionic dodecyldimethylammonium propane sulfonate (CPS)) on these BCPs is examined to observe their influence on micellization behaviour.

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Objective: This study aimed to develop a mixed polymeric micelle formulation incorporating candesartan cilexetil (CAND) drug to enhance its oral bioavailability for the better treatment of hypertension.

Methods: A Box-Behnken design was utilized to optimize the CAND-incorporated mixed polymeric micelles formulation (CAND-PFLC) consisting of Pluronics (P123 and F68) and lecithin (LC). The optimized CAND-PFLC micelles formulation was characterized for size, shape, zeta potential, polydispersity index (PDI), and entrapment efficiency (%EE).

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