Unraveling the solubilization and cytotoxicity study of poorly water-soluble anti-inflammatory drug in aqueous Gemini surfactants solution with physicochemical characterization and simulation study

Additive-anchored thermoresponsive nanoscale self-assembly generation in normal and reverse Tetronics®

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 Na2SO4), nonelectrolyte polyols (glucose and sorbitol), and ionic surfactants (viz. anionic-sodium dodecyl sulfate (SDS), cationic-dodecyltrimethylammonium bromide (DTAB) and zwitterionic dodecyldimethylammonium propane sulfonate (C12PS)) on these BCPs is examined to observe their influence on micellization behaviour. The presence of salts and polyols displayed interesting phase behaviour, i.e., the cloud point (CP) was decreased, the water structure was affected and the micelles were dehydrated by expelling water molecules, and thus they were likely to promote micelle formation/growth. In contrast, ionic surfactants in small amounts interacted with the BCPs and showed an increase in CPs thereby forming mixed micelles with increasing charges and decreasing micellar sizes, finally transforming to small surfactant-rich mixed micelles. Molecular interactions such as electrostatic and hydrogen bonding involved within the examined entities are put forth employing a computational simulation approach using the Gaussian 09 window for calculation along with the GaussView 5.0.9 programming software using the (DFT)/B3LYP method and 3-21G basis set. The hydrodynamic diameter (Dh) of the micelles is examined using dynamic light scattering (DLS), while the various micellar parameters inferring the shape/geometry are obtained using small-angle neutron scattering (SANS) by the best fitting of the structure factors. It is observed that 10 w/v% T904 remains as spherical micelles with some micellar growth under physiological conditions (37 °C), while 10 w/v% T90R4 remains as unimers and forms spherical micelles in the presence of additives at 37 °C. Furthermore, the additive-induced micellar systems are tested as developing nanovehicles for anticancer (curcumin, Cur) drug solubilization using UV-vis spectroscopy, which shows a prominent increase in absorbance with enhanced solubilization capacity. Additionally, the cytotoxic effect of Cur loaded on the BCP micelles in HeLa cells is studied through confocal microscopy by capturing fluorescence images that depict HeLa cell growth inhibition under the influence of additive-induced micellar systems.

Salt induced micellization conduct in PEO-PPO-PEO-based block copolymers: a thermo-responsive approach

The nanoscale self-assembly behavior in ethylene oxide (EO) and propylene oxide (PO)-based block copolymers (BCPs) commercially available as Pluronics®: L44 (PEO10-PPO23-PEO10) and F77 (PEO53-PPO34-PEO53) is put forth in aqueous solution and in the presence of sodium salts NaCl and Na2SO4. The moderate hydrophilicity of L44 is attributed to its low molecular weight PPO segment, while the high percentage of PEO content in F77 contributes to its extreme hydrophilicity. The impact of sodium salts (NaCl and Na2SO4) on the self-assembly is investigated to understand their influence and role in micellization, by employing various physicochemical techniques such as phase behavior conduct, calorimetry, tensiometry, scattering, and spectral analysis. The results indicate that at a low temperature range of 20-30 °C, Pluronics® solutions with a concentration of 10% w/v remain molecularly dissolved as individual units called unimers (Gaussian chain), which have a hydrodynamic size (Dh) of approximately 4-6 nm. Additionally, loose clusters of a few hundred nanometers in size are also observed. Though, at higher concentrations of BCPs and in the presence of salt or elevated temperatures, the examined micellar structures exhibit a higher degree of organization i.e., spherical or ellipsoidal in terms of size and shape. Also, the solubilization enhancement of a hydrophobic dye called orange OT within the examined micellar system is also undertaken using a spectral approach.

Rationalizing the Design of Pluronics-Surfactant Mixed Micelles through Molecular Simulations and Experiments

Aqueous systems comprising polymers and surfactants are technologically important complex fluids with tunable features dependent on the chemical nature of each constituent, overall composition in mixed systems, and solution conditions. The phase behavior and self-assembly of amphiphilic polymers can be changed drastically in the presence of conventional ionic surfactants and need to be clearly understood. Here, the self-aggregation dynamics of a triblock copolymer (Pluronics L81, EO₃PO₄₃EO₃) in the presence of three cationic surfactants (with a 12C long alkyl chain but with different structural features), viz., dodecyltrimethylammonium bromide (DTAB), didodecyldimethylammonium bromide (DDAB), and ethanediyl-1,2-bis(dimethyldodecylammonium bromide) (12-2-12), were investigated in an aqueous solution environment. The nanoscale micellar size expressed as hydrodynamic diameter (D_h) of copolymer-surfactant mixed aggregates was evaluated using dynamic light scattering, while the presence of a varied micellar geometry of L81-cationic surfactant mixed micelles were probed using small-angle neutron scattering. The obtained findings were further validated from molecular dynamics (MD) simulations, employing a simple and transferable coarse-grained molecular model based on the MARTINI force field. L81 remained molecularly dissolved up to ∼20 °C but phase separated, forming turbid/translucent dispersion, close to its cloud point (CP) and existed as unstable vesicles. However, it exhibited interesting solution behavior expressed in terms of the blue point (BP) and the double CP in the presence of different surfactants, leading to mixed micellar systems with a triggered morphology transition from unstable vesicles to polymer-rich micelles and cationic surfactant-rich micelles. Such an amendment in the morphology of copolymer nanoaggregates in the presence of cationic surfactants has been well observed from scattering data. This is further rationalized employing the MD approach, which validated the effective interactions between Pluronics-cationic surfactant mixed micelles. Thus, our experimental results integrated with MD yield a deep insight into the nanoscale interactions controlling the micellar aggregation (Pluronics-rich micelles and surfactant-rich micelles) in the investigated mixed system.

Cationic gemini surfactant properties, its potential as a promising bioapplication candidate, and strategies for improving its biocompatibility: A review

Gemini surfactants consist of two cationic monomers of a surfactant linked together with a spacer. The specific structure of a cationic gemini surfactant is the reason for both its high surface activity and its ability to decrease the surface tension of water. The high surface activity and unique structure of gemini surfactants result in outstanding properties, including antibacterial and antifungal activity, anticorrosion properties, unique aggregation behaviour, the ability to form various structures reversibly in response to environmental conditions, and interactions with biomacromolecules such as DNA and proteins. These properties can be tailored by selecting the optimal structure of a gemini surfactant in terms of the nature and length of its alkyl substituents, spacer, and head group. Additionally, regarding their properties, comparison with their monomeric counterparts demonstrates that gemini surfactants have higher performance efficacy at lower concentrations. Hence, less material is needed, and the toxicity is lower. However, there are some limitations regarding their biocompatibility that have led researchers to develop amino acid-based and sugar-based gemini surfactants. Owing to their remarkable properties, cationic gemini surfactants are promising candidates for bioapplications such as drug delivery systems, gene carriers, and biomaterial surface modification.

Profound implication of histological alterations, haematological responses and biocidal assessment of cationic amphiphiles unified with their molecular architecture

The interfacial properties depicting the micellization behaviour of the cationic amphiphiles (surfactants) belonging to the class of quaternary ammonium salts varying in degree of hydrophobicity were evaluated using tensiometry, conductivity and fluorescence spectrophotometric methods at 303.15 K. The impact of the amphiphilic nature of these amphiphiles as a function of their concentration is accounted against the selective microbial strains using the well-diffusion approach. Also, its influence on the histological (shrinkage/curling of lamellae, necrosis, haemorrhage, hyperplasia of villi in gills and intestine) alterations and haematological (blood parameters) changes in fingerling of Cirrhinus mrigala (C. mrigala) offers an insight into the stern damages reported as aquatic toxicity. The lesions exhibited moderate to severe alterations that are further correlated with the semi-quantitative mean alteration value (MAV). The in vitro and in vivo findings are explained significantly in terms of amphiphilic hydrophobicity which followed the order: C₁₆TAB > C₁₂TAB. All the observed outcomes are rationalized by the structural assessment of the selected amphiphiles as specified by the computational simulation approach using density functional theory (DFT) with B3LYP method and 3-21G basis source set. This work also portrays the biodegradability of these cationic amphiphiles and their fate on the environment. Graphical abstract Molecular architecture of cationic amphiphiles integrated with their in vitro and in vivo rejoinders.

In vitro toxicity assessment and enhanced drug solubility profile of green deep eutectic solvent derivatives (DESDs) combined with theoretical validation

Green solvents are actively taking over as the absolute replacement of intrinsic toxic volatile organic solvents. This is conspicuously analyzed in this study, which mentions the preparation of green deep eutectic solvent derivatives (DESDs) composed of choline chloride (ChCl) as the hydrogen bond acceptor (HBA) and two acids, viz., oxalic acid (OX) and citric acid (CA) as preliminary hydrogen bond donors (HBDs) with ethylene glycol (EG) and glycerol (GLY) as secondary HBDs in an equimolar ratio. This study exposes the vigilant choice of the type and mole ratio of HBA and HBDs, which permit the extended stability of the formulated DESDs in the liquid state even below the room temperature. The prepared DESDs were well-characterized by FT-IR spectroscopy. Furthermore, this work aimed at investigating their antimicrobial activity towards selected bacterial and fungal strains expressed in terms of viscosity measurements. The in vitro toxicity profiles in terms of cytotoxicity (human cervical cancer cell line) and genotoxicity (DNA fragmentation), which have not been reported to date, were also assessed for the prepared DESDs. Tuning the HBA and HBDs in selected DESDs for promising biological activity was found to have ethical implications. In addition, this study focused on the solubilization enhancement of the local anaesthetic drug lidocaine (LDC) in the stated DESDs as a function of water composition, and higher solubility was observed due to the fair intermolecular hydrogen bonding interactions between LDC and DESDs, which was further validated using the computational simulation approach. In addition, the electron-donating and accepting sites were depicted by 3D-molecular electrostatic potential (3D-MEP) for the examined systems. The observed variations were attributed to the changes in the solvation capacity, viscosity and ionic strength of pure DESDs as a function of water concentration. Finally, this study supports the role of dual HBDs in leading to the formation of stable DESDs with noteworthy action towards drug solubilization and a remarkable biological response.

Scheme illustrating the sustainable preparation of deep eutectic solvent derivatives (DESDs), their biological response and water-insoluble hydrophobic drug dissolution trend.

Biotoxicity and tissue-specific oxidative stress induced by Gemini surfactant as a protocol on fingerlings of Cirrhinus mrigala (Ham.): An integrated experimental and theoretical methodology

An increasing concern for Gemini surfactants (GS) based on the class alkanediyl-α-ω-bis (dimethylalkylammonium bromide) has been reported in ecotoxicological researchbecause of their estrogenic properties causing an alarm to aquatic life. In this study, we analyzed the toxic effects of the synthesized GS (12-2-12 and 16-2-16) leading to histological changes in fingerlings (kidney, gills, intestine, and liver) of Cirrhinusmrigala. Damage in the tissues in correlation with their normal architecture was observed microscopically and was manifold. The tissue-specific morphological alterations associated with somatic index (MAV- mean alteration value) were used as biomarker. The present study also highlighted the changes in the antioxidant enzymes such as superoxide dismutase (SOD) and catalase (CAT). In order to estimate the sub-lethal toxic properties of GS, the genotoxicity and cytotoxicity of GS were evaluated using blood smear assay and HeLa cell line respectively. Results of the study exhibited potential biotoxicity where GS with the highest hydrophobicity showed upper most toxicity level under different exposure time, while GS with less hydrophobic features exhibited least stressful regimeto the tested animal. The prepared GS were also examined for their biodegradability following the die-away method. The theoretical approach estimates the structural information by computational simulation.