Ethayaraja Mani

Control over synthesis conditions is necessary to ensure high loading in polymer-encapsulated iron oxide nanoparticles (P-IONPs) and enable biomedical applications. While flash nanoprecipitation (FNP) is a robust method to fabricate P-IONPs, very little is known regarding the response of hydrophobic IONPs to the change in solvent quality during FNP and its effect on the nature of encapsulation. In this work, we first probe the sizes of oleic acid (OA)-coated IONPs at varying compositions of water (ϕw) in a tetrahydrofuran (THF)–water mixture through time-based dynamic light scattering (DLS) and cryo-electron microscopy. It was found that OA-IONPs existed as large (micron)-sized clusters in THF, which broke into smaller clusters as ϕw in the solvent mixture increased. A free energy model of clustering is presented to describe the competing repulsive and attractive interparticle interactions driving the equilibrium cluster sizes (d*) as a function of ϕw. This effect was further pronounced when an aqueous Tween 80 solution was added to the dispersion, resulting in individually dispersed IONPs at high ϕw. The d* directly influenced the nature of P-IONPs produced using FNP at varying aqueous-to-organic flow rate ratios. Finally, a systematic study was performed to investigate the effects of the concentration of polymer and IONPs, and OA surface coverage on IONPs, on the extent and nature of encapsulation. The findings suggest the key role of competing colloidal interactions in governing the fate of synthesized P-IONPs via FNP. The understanding from this study would enable the rational design of P-IONPs with high, uniform loading for desired applications.

Nanoplastics are increasingly being recognized as a global pollutant. However, relatively few studies report directly measured concentrations of nano- and microplastics in environmental samples, although available data suggest levels of up to 0.5 mg L⁻¹ in lake water, which is surprisingly high. Their degradation in the environment, particularly under UV irradiation, is still poorly understood. Here, we investigated the effect of UVB irradiation on polystyrene nanoparticles of different sizes (99 nm to 200 nm) and evaluated whether iron oxide nanoparticles accelerate their breakdown. Particle size and mass changes were monitored using differential centrifugal sedimentation (DCS), dynamic light scattering (DLS), and nanoparticle tracking analysis (NTA). Our results show that UV-mediated degradation was size-dependent, with larger nanoparticles breaking down more rapidly than the smaller ones under identical mass concentrations. The addition of iron oxide nanoparticles accelerated the UVB-mediated breakdown of the 99 nm particles, leading to a >100-fold reduction in particle concentration and loss of toxicity in Daphnia magna assays after 111 days. Mechanical breakdown experiments demonstrated that the larger particles were more susceptible to size reduction than the smaller particles. Together, these findings suggested that small nanoplastic particles may accumulate in natural environments due to their slower degradation, but iron oxide could serve as an effective and low-cost remediation strategy for accelerating their breakdown and mitigating toxicity.

Interferon-α2a (IFN-α2a), a cell-signaling therapeutic protein, is effective in treating diseases such as cancer and hepatitis. However, their clinical application is limited by rapid degradation and clearance from the body. PEGylation improves its stability and in vivo circulation time but raises concerns over immunogenicity and poor biodegradability. Polysarcosine (PSar), a biodegradable and biocompatible polypeptoid with PEG-like solubility, reduced immune recognition, and tunable properties, presents a promising alternative to PEG. We present here all-atom molecular dynamics (MD) simulations demonstrating that the interactions and stabilizing effects of polysarcosine (PSar) are similar to those of poly(ethylene glycol) (PEG) on IFN-α2a. Both polymers preserve the native protein fold across concentrations, with PSar producing a lower root-mean-square deviation (RMSD) of protein residues from their reference configurations than does PEG. Both polymers suppress hydrogen bonding of the protein with water by up to 10% at polymer concentrations typically produced by PEGylation, while creating similarly large numbers of polymer contacts with IFN-α2a, mostly, but not exclusively, with polar residues, suggesting that PSar is likely just as effective as PEG in preventing IFN-α2a aggregation. These atomistic insights highlight the enhanced ability of PSar to retain the structural stability of IFN-α2a, shielding it against aggregation as well as does PEG, reinforcing its potential as a next-generation, nonimmunogenic alternative to PEG for therapeutic protein stabilization.

Background: Diabetes mellitus is a progressive metabolic disorder characterise by chronic hyperglycemia and impaired carbohydrate metabolism. Despite the availability of synthetic antidiabetic agents, their long-term administration is often associated with adverse effects, which stresses the urgent need for safer alternatives of plant origin. Sida cordata is a traditionally valued medicinal plant reported to exhibit antidiabetic and organ-protective actions; however, its detailed molecular mechanism for antidiabetic activity is not yet well established. Aim: To explore in depth, through in silico molecular docking and molecular dynamics simulations, the potential mechanisms of S. cordata phytoconstituents as an antidiabetic agent against important protein targets associated with diabetes. Methods: Twenty-eight S. cordata phytoconstituents were screened against four diabetes-related proteins (PDB IDs: 7VSI, 7WMV, 4EMA and 1KAV) using Schrödinger Glide for molecular docking. The stability and dynamic behavior of the top-scoring protein-ligand complexes were further investigated by molecular dynamics simulations conducted with GROMACS.ADMET and drug-likeness were predicted using SwissADME to assess pharmacokinetics. Results: The molecular docking analysis of all screened phytoconstituents revealed favorable binding affinities as evidenced by the obtained docking scores ranging from -1.4 to -12.9 kcal/mol. Notably, α-D-glucopyranoside, O-α-D-glucopyranosyl-(1→3)-α-D-fructofuranosyl exhibited the highest and most consistent binding to all targets, reaching a maximum docking score of -12.9 kcal/mol against 7VSI. Thus, an interaction analysis was conducted, which revealed stable hydrogen bonding and hydrophobic interactions within the active site. Molecular dynamics simulations demonstrated structural stability for both 7VSI-lead compound and 7VSI-standard complexes, with the least root-mean-square deviation for the entire period of the simulation study. The ADMET analysis revealed that the selected lead compound exhibited acceptable pharmacokinetic properties, good oral bioavailability, and no predicted toxicity. These findings support its drug-likeness and suitability for further antidiabetic development. The current findings support the antidiabetic potential of S. cordata, in particular its α-D-glucopyranoside derivatives, through in silico results indicating high binding affinities and biologically stable protein-ligand interactions with target proteins associated with diabetes. Major Findings: Sida cordata phytoconstituents demonstrated strong and consistent binding to multiple diabetes-related protein targets. The α-D-glucopyranoside derivative emerged as a stable lead compound, validated through molecular docking and dynamics simulations.

Microplastics (MPs, <5 mm) and nanoplastics (NPs, <1 μm) generated from plastic waste are emerging as a global environmental and health-related challenge affecting life in water and soil.

Stimuli-induced interfacial destabilization of oil–water emulsions is an attractive approach for emulsion processing, as it typically requires less energy input than conventional bulk manipulation methods. In this work, we demonstrate the photoinduced destabilization and reconstruction of n-decane-in-water emulsions that were rendered highly stable (>45 days) with the help of an azobenzene-containing cetyltrimethylammonium bromide (Azo-CTAB) surfactant. Phase separation was induced easily in Azo-CTAB stabilized emulsions by the illumination of ultraviolet (UV) light, which activates photoisomerization of the Azo-CTAB molecule and would, in turn, affect its interfacial adsorption. A simple analysis based on the size of the dispersed phase droplets shows that phase separation occurs by coalescence of the droplets, following second-order kinetics. The coalescence rate constant is higher by about 5 orders of magnitude when demulsification is induced by UV exposure, compared to those in samples stored under ambient conditions. The degree of phase separation can be controlled by tuning various factors, such as the power intensity of UV light, the addition of an electrolyte, and the addition of a mutually soluble solute. The coalescence rate is faster by about 4–5 times in the presence of an added electrolyte (NaCl). When UV light of low intensity (∼1 mW cm–2) is used, complete demulsification can still be achieved if a small quantity of a volatile liquid such as ethanol is added to the emulsion. More interestingly, we show that the original emulsion can be reconstructed by subsequently illuminating the phase-separated mixture with visible light, thus demonstrating photoswitchability in Azo-CTAB stabilized emulsions. The reversible photoswitchability persists for multiple (5–7) cycles, without any appreciable change in the appearance and size of the dispersed droplets. These results have great significance in applications that require repeated and facile stabilization and destabilization of emulsions, such as oil recovery and wastewater treatment.

Overview of gold nanoparticle synthesis using binary surfactants: key mechanisms and future directions.