Decrease In Polydispersity Index Research Articles

Antimicrobial and antioxidant therapy with bioactive plant molecules on Fe3O4 phytohybrid nanoplatforms

BackgroundNanobiomedicines have gained increasing attention for their potential to improve efficacy and are emerging as a promising therapeutic paradigm. Magnetic nanoconjugates loaded with bioactive drugs have the advantage of sustained circulation in the bloodstream and significantly reduced toxicity of therapeutic agents in a precise manner. The well-developed surface chemistry of Fe3O4 has led to the development better tools, promoting them as nanoplatforms with potential technological applications in biomedical sciences.ResultsFe3O4 phytohybrids with Laxmitaru extract as the primary coating and loaded with Eugenol and Ylang-Ylang essential oils were successfully synthesized. The X-ray diffraction technique has revealed the high purity nanoparticle materials, as no additional impurity peaks were observed. Fourier transform infra-red spectra have confirmed the presence of a primary coating of Laxmitaru extract and a secondary layer of essential oil, as additional peaks and broadening are observed in drug-loaded Fe3O4 nanoparticles. Magnetic susceptibility values indicate the material's superparamagnetic nature. Transmission electron microscopy images have ensured that the particles were spherical, monodispersed, and in the range of 4.30 nm to 13.98 nm. Antimicrobial studies show inhibition zones on the microorganisms S. Aureus and E. Coli with enhanced activity. Drug entrapment efficiency studies revealed the encapsulation of drug molecules onto Fe3O4-Laxmitaru composite. Dynamic light scattering studies confirm the increase in hydrodynamic size, indicating the loading of essential oils and the decrease in polydispersity index ensures monodispersed nanoparticles. The antioxidant study showed the essential oils retained their antioxidant activity even after they were conjugated on Fe3O4-Lax composites.ConclusionsLaxmitaru phytochemical-coated Fe3O4 nanoparticles were successfully conjugated with Eugenol and Ylang-Ylang essential oils. Our results provide a model therapeutic approach for the development of new alternative strategies for enhancing antimicrobial and antioxidant therapy, with potential advantages in the field of nanobiomedicine.

Optimizing microfluidic preparation parameters of nanosuspension to evaluate stability in nanoprecipitation of stable-iodine (127I)

The aim of the current study was the development of nanosuspension stability in nanoprecipitation using microfluidic devices. Also, it is desirable to understand how the microfluidic preparation parameters influenced the stability of the stable-iodine (127I) nanosuspension. In optimization process through artificial neural networks (ANNs), the relations between input and output variables were investigated for 37 samples obtained by microfluidic nanoprecipitation process. Solvent temperature, antisolvent flow rate, and solvent flow rate were used as input variables, and the sedimentation time and polydispersity index (PDI) were considered as output parameters. Sedimentation time as an indicator of physical stability of nanosuspension was evaluated by observation of a densely packed sediment. Also, size and PDI of different samples were determined by dynamic light scattering. The size of the optimized sample was confirmed by transmission electron microscopy. The result obtained from modeling showed that increasing solvent temperature and antisolvent flow rate led to a decrease in PDI and an increase in the sedimentation time. The antisolvent flow rate was determined as the most important factor that affected the sedimentation time and PDI. Increasing the solvent flow rate was identified as an adverse factor which increased PDI or decreased formulation’s sedimentation time. Optimization using ANN showed that microfluidic preparation parameters of nanosuspension as input variables had potential impacts on output parameters.

Submicellar aggregates in aqueous sodium dodecyl sulphate solutions: Investigations by dynamic light scattering and water penetration through porous media

Aqueous solutions of sodium dodecyl sulphate (SDS) are investigated by dynamic light scattering (DLS) and water penetration/wettability in porous hydrophobic chalk. The polydispersity index (PDI) and wettability are correlated with change in the population density of submicellar fragments. It is concluded that the number of submicellar fragments in aqueous surfactant solution is significantly reduced as a function of SDS concentration and in presence of different additives, namely sodium chloride (NaCl), dodecanol (C12OH) and dodecyl trimethyl ammonium bromide (C12TAB). The decrease in wettability and changes in polydispersity index (PDI) of micelles is correlated with the concentration of submicellar aggregates in aqueous solutions. The decrease in PDI as observed by DLS is a result of formation of stable micelles and subsequent reduction in population of submicellar aggregates. The water penetration in dustless chalk is primarily controlled by the rate of diffusion and subsequent adsorption of submicellar aggregates to the porous capillaries. With formation of stable micelles and reduction in number of submicellar aggregates, a peculiar reduction in water penetration is noted. The observed trend is described in terms of concentration of submicellar fragments under different conditions of surfactant solution.

비수계 분산중합으로 제조된 환경친화성 아크릴수지/나노클레이 복합재료의 특성 연구

Eco-friendly acrylic resin/clay nanocomposites containing pristine montmorillonite (PM) or modified clays (30B and 25A) were prepared from acrylic and styrenic monomers using non-aqueous dispersion (NAD) polymerization. Effect of nanoclays on physical properties of polymerization product and resulting nanocomposites was investigated. In view of NAD particle stability, addition of nanoclay at the beginning of polymerization is proved to be good. Results of gel fraction, acid value and viscosity of the NAD product showed that nanocomposites containing clay 25A showed better physical properties than the ones with other clays. GPC results exhibit the increase in molecular weight and decrease in polydispersity index for the 25A nanocomposite. Increase in layer distance confirmed from XRD analysis showed good dispersion of 25A in the nanocomposite. Thermal and dynamic mechanical analysis showed that highest glass transition temperature and storage modulus for 25A nanocomposites. These results indicate that 25A nanoclay gives the best properties in the process of non-aqueous dispersion polymerization of acrylic resin/nanoclay nanocomposites.

Modeling methyl methacrylate free radical polymerization in nanoporous confinement

Nanoconfinement of methyl methacrylate free radical polymerization is known to impact the molecular weight and molecular weight distribution of the polymer produced, with results in the literature generally indicating an increase in molecular weight and a concomitant decrease in polydispersity index. In the present work, the mathematical model described by Verros et al. (2005) for free radical bulk polymerization of methyl methacrylate is extended to account for polymerization in nanopores. The model of Verros et al. (2005) incorporates diffusion effects and is capable of describing the conversion and the number- and weight-average molecular weights of the resulting poly(methyl methacrylate) as a function of polymerization time and process conditions. The model is extended by incorporating the effect of nanoconfinement on diffusivity using the scaling reported in the literature. The calculations indicate that nanoconfinement will lead to higher molecular weights and lower polydispersity, and the gel effect will occur earlier. The results are compared to experimental work and implications discussed.

Bis-ureidodeazapterin (Bis-DeAP) as a general route to supramolecular star polymers

Supramolecular recognition unit Bis-DeAP, 1, containing two high affinity hydrogen-bonding acceptor–acceptor–donor–donor (AADD) arrays was designed to self-assemble into cyclic assemblies. It was prepared through a highly scalable synthesis and was further functionalized with 2-bromo-2-methylpropanoyl bromide and used to initiate the polymerization of methylmethacrylate (MMA). Bis-DeAP–PMMA polymers quantitatively self-assembled into star polymers in toluene. In DMF Bis-DeAP–PMMA forms a mixture of star polymers and unassembled polymers. Bis-DeAP was also functionalized with polyethylene glycol (PEG) polymers. The Bis-DeAP–PEG polymers formed star polymers in DMF; however, higher molecular weight polymeric assembles that varied with concentration were observed in water. Mixing studies in toluene indicated that the self-assembled star polymers are kinetically stable and resist mixing even at elevated temperatures. In DMF, kinetically controlled structures are initially observed, however, mixing occurs at a faster rate and assembled star polymers show a decrease in polydispersity index (PDI) over time. In addition, Bis-DeAP functionalized PS and PMMA were mixed in DMF to generate a star copolymer through self-assembly.

Flow-induced chain scission as a physical route to narrowly distributed, high molar mass polymers

We present data showing a substantial narrowing of the polydispersity index (PDI) of high polymers occurring as a consequence of random chain scission events in a transient elongational flow field. In our experiments, semi-dilute aqueous solutions of high-molar mass, polydisperse polymers (PDI>1.4) were injected under pressure through an elongational flow field at the entrance of a capillary tube (i.d. 250 μm). Chain scission events occurring during multiple passes through the capillary entrance cause a marked decrease in PDI, to values as low as 1.12, along with the expected decrease of the average molar mass. The phenomenon appears to be entirely physical and independent of the chemical nature of the polymer, since similar results are obtained with polyacrylamide, polydimethylacrylamide, and poly(ethylene oxide). Statistical modeling of the evolution of the polymer molar mass distribution shows the results to be consistent with the random scission, near the mid-point, of those polymer chains that exceed a certain flow field-dependent critical chain length.

Step polymerisation with unequal reactivities in a CSTR

A mathematical model for step polymerisation of BB with AA in a CSTR where the functional groups of AA are not equally reactive has been developed. Unequal reactivity can be due to either asymmetry or induced asymmetry. The polydispersity index (PDI) of the product of a CSTR was calculated and was found to be always greater than that of a batch reactor. Calculations show that, when compared with situations where unequal reactivity is absent, the presence of induced asymmetry can cause either an increase or a decrease in PDI while the presence of asymmetry can only cause a decrease in PDI. However where BB is in excess of AA in the feed, the limit of the calculated PDI as residence time tends to infinity was unaffected by unequal reactivity.

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Aqueous solutions of sodium dodecyl sulphate (SDS) are investigated by dynamic light scattering (DLS) and water penetration/wettability in porous hydrophobic chalk. The polydispersity index (PDI) and wettability are correlated with change in the population density of submicellar fragments. It is concluded that the number of submicellar fragments in aqueous surfactant solution is significantly reduced as a function of SDS concentration and in presence of different additives, namely sodium chloride (NaCl), dodecanol (C12OH) and dodecyl trimethyl ammonium bromide (C12TAB). The decrease in wettability and changes in polydispersity index (PDI) of micelles is correlated with the concentration of submicellar aggregates in aqueous solutions. The decrease in PDI as observed by DLS is a result of formation of stable micelles and subsequent reduction in population of submicellar aggregates. The water penetration in dustless chalk is primarily controlled by the rate of diffusion and subsequent adsorption of submicellar aggregates to the porous capillaries. With formation of stable micelles and reduction in number of submicellar aggregates, a peculiar reduction in water penetration is noted. The observed trend is described in terms of concentration of submicellar fragments under different conditions of surfactant solution.