A series of copolymeric nanoparticles of methyl methacrylate and N-vinylcaprolactam were synthesized from microemulsions containing sodium dodecyl sulfate. Etoposide as a model drug was loaded in nanoparticles during in situ polymerization. Stable nanolatex were produced and characterized for size and shape by dynamic light scattering (DLS) and transmission electron microscopy. Particles were found to be spherical in nature with size less than 50 nm. Structural characterization of copolymers was done by infrared and nuclear magnetic resonance spectroscopy. Differential scanning calorimetery (DSC) and X-ray diffractometry (XRD) techniques were used to evaluate molecular level interaction of etoposide with nanoparticles. Drug encapsulation efficiency was determined by ultraviolet (UV) spectrometry and found to be 3567%. DSC, XRD, and UV data suggested the molecular level dispersion of drug in the nanoparticles. In vitro release studies and in vitro cytotoxicity showed prolonged and controlled release of etoposide from nanoparticles along with IC50 values of nanoparticles in the range of 0.010.1 mg/mL. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2013

Copolymeric nanoparticles of methyl methacrylate (MMA) and N-vinylcaprolactam (VCL) were prepared through free radical polymerization using hydrogen peroxide and L-ascorbic acid as a redox initiator in o/w microemulsion containing sodium dodecyl sulphate (SDS). The copolymers were characterized by FTIR and gel permeation chromatography (GPC) and composition of copolymer was determined by H-1 NMR spectroscopy. Reactivity ratio was determined by linear least square and non-linear least square methods. The morphology and particle size distribution of copolymer latexes was determined through transmission electron microscopy (TEM) and dynamic light scattering (DLS). Copolymers were of less than 50 nm size with spherical morphology and latexes were stable for more than 6 months. Phase transition temperature measured through UV-vis spectrometry, for the synthesized copolymer indicates their potential use in biosensors and targeted drug delivery system. Cytotoxicity of nanoparticles was determined by MTT assay on B16F10 melanoma cell lines. Cell viability data shows the IC50 values of copolymeric nanoparticles to be in the range of 0.01-0.1 mg/mL. (C) 2010 Elsevier Ltd. All rights reserved.

The venlafaxine hydrochloride (VHL)-loaded chitosan nanoparticles were prepared by ionic gelation of chitosan (CS) using tripolyphosphate (TPP). The nanoparticles were characterized using FTIR, differential scanning calorimetry, X-ray diffraction, dynamic light scattering, transmission electron microscopy, and X-ray photoelectron spectroscopy. The effect of concentration of CS, polyethylene glycol (PEG), VHL and CS/TPP mass ratio on the particle size and zeta potential of nanoparticles was examined. The particle size of CS/TPP nanoparticles and VHL-loaded CS/TPP nanoparticles was within the range of 200-400 nm with positive surface charge. In the case of VHL-loaded nanoparticles and PEG-coated CS/TPP nano-particles, the particle size increases and surface charge decreases with increasing concentration of VHL and PEG. Both placebo and VHL-loaded CS/TPP nanoparticles were observed to be spherical in nature. PEG coafing on the surface of CS/TPP nanoparticles was confirmed by XPS analysis. Maximum drug entrapment efficiency (70%) was observed at 0.6 mg/mL drug concentration. In vitro drug release study at 37 degrees C +/- 0.5 degrees C and pH 7.4 exhibited initial burst release followed by a steady release. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 112: 2876-2887, 2009

Silver nanoparticles were prepared by microwave irradiation of silver nitrate (AgNO3) solution in ethanolic medium using polyvinylpyrrolidone (PVP) as a stabilizing agent. Ethanol was observed to act as a reducing agent in the presence of microwave. Appearance of surface plasmon band at 416nm indicated the formation of silver nanoparticles. Highly monodispersed stable polycrystalline silver nanoparticles were obtained within 5s of microwave irradiation. Through transmission electron microscopy silver nanoparticles were observed to be spherical with 10±5nm diameter. Silver nanoparticles exhibited fluorescence band at 491nm.

Gold–silver alloy nanoparticles were synthesized by simultaneous reduction of varying mole fractions of HAuCl4 and AgNO3 by sodium citrate in aqueous solution without using stabilizing agents such as surfactant or polymer. Appearance of single absorption peak in visible spectrum indicated formation of homogeneous gold–silver alloy nanoparticles. Transmission electron micrographs also support formation of alloy nanoparticles rather than core–shell particles. The plasmon absorption bands for Au–Ag nanoparticles show linear bathochromic shift with increasing Au content. No significant change in surface plasmon band was observed on storage of samples at 25±2°C for 6 months, indicating stability of the particles. Particle size distribution, zeta-potential and conduction of these colloidal suspensions were measured by dynamic light scattering along with Zetasizer. Gold and Au–Ag alloy nanoparticles exhibited fluorescence at 600nm and in between 600 and 486nm respectively depending on alloy composition. Gold nanoparticles were used for cell line study using liposome as a carrier. This liposome entrapped gold nanoparticles showed enhanced uptake by Chinese Hamster Ovary (CHO) cells compared to gold nanoparticles.

Platinum nanoparticles of less than 5nm size have been synthesized by the reduction of H2PtCl6 using sodium borohydride in water-in-oil (w/o) microemulsions of water/TritonX-100/cyclohexene/1-hexanol at 25±2°C. Size and shape of the particles are determined through HRTEM images.

Highly stable gold–silver alloy nanoparticles with varying mole fractions were prepared in aqueous sodium dodecyl sulfate solution by simultaneous reduction of chloroauric acid (HAuCl4) and silver nitrate (AgNO3) using sodium citrate. The formation of alloy nanoparticles was confirmed by UV-visible spectroscopy and transmission electron microscopy. Particle size distribution was measured by dynamic light scattering. The surface plasmon absorption band of the Au–Ag alloy nanoparticles shows linear bathochromic shift with increasing Au content. Appearance of a single absorption peak in the visible region and lack of apparent core-shell structures in the transmission electron microscope images confirm the formation of homogeneous gold–silver alloy nanoparticles.

Porcine liver esterase was entrapped in natural polysaccharides K-carrageenan and retention of its activity was determined using p-nitrophenyl acetate as the substrate. The optimum pH for esterase activity of entrapped enzyme showed a little shift towards acidic side. Immobilized enzyme showed improved thermal and storage stability. The entrapped esterase retained 50% of its activity after eight repetitive cycles. Michaelis constant K for the free and entrapped enzymes was almost same indicting no conformational change during immobilization. Maximum velocity V,a, was observed to decrease on immobilization. The free and entrapped esterase was used for selective hydrolysis of methyl 2-acetoxybenzoate to methyl 2-hydroxybenzoate in batch process as well as in a fixed bed reactor. The hydrolysis was observed to be 99% within 2 h for free as well as immobilized enzyme in batch process. The rate of hydrolysis was found to depend on pH. The turn over number of selective hydrolysis in batch and fixed bed reactor was 3.08 x 10(6) and 1.19 x 10(7), respectively. (C) 2008 Wiley Periodicals, Inc.

Anisotropic palladium and platinum nanoparticles were synthesized by reduction of the corresponding metal ions with hydrazine using polyacrylamide as a stabilizing agent in aqueous medium under microwave irradiation. The formation of particles was confirmed by UV-visible spectroscopy. The size and shape of the particles were determined using transmission electron microscopy. Rapid microwave heating resulted in ‘star-shaped’ palladium nanoparticles, but platinum nanoparticles were observed to be spherical with a distinctly visible 3–4 nm coating of polyacrylamide on their surface, which was not observed for the palladium particles. The Pt nanoparticles were used as a catalyst in the redox reaction.

A series of copolymeric nanoparticles of the partially water-soluble monomer ethyl methacrylate and the water-soluble monomer 2-hydroxyl ethyl methacrylate were synthesized from emulsions containing sodium dodecyl sulfate via free-radical polymerization. Lamotrigine, as a model drug, was loaded in nanoparticles during in situ polymerization. A stable and transparent poly(ethyl methacrylate-co-hydroxyl ethyl methacrylate) nanolatex was produced for all compositions and characterized for particle size by dynamic light scattering and transmission electron microscopy. Particles were found to be smaller than 50 nm in size. Structural characterization of copolymers was done by infrared spectrometry, gel permeation chromatography, and NMR spectroscopy. Drug encapsulation efficiency was determined by ultraviolet (UV)-visible spectrometry and was found to be 26-62% for copolymers with different compositions. UV data suggest molecular-level dispersion of the drug in the nanoparticles. In vitro drug-release studies showed the controlled release of lamotrigine. (c) 2007 Wiley Periodicals, Inc.

Influence of bivalent malate on aggregation behavior of butanediyl-1,4-bis(dodecyl hydroxyethyl methyl ammonium bromide) (12-4-12 MEA) surfactant was studied through SANS and conductometric measurements. Critical micelle concentration (CMC), Krafft temperature, foamability, foam stability, oil solubilization capacity and aggregation number showed maxima or minima at 12-4-12 MEA: Na-malate concentration ratio 1:0.5. Complete disappearance of charged on micelles was observed on addition of equivalent or excess amount of Na-malate. No significant change was observed in aggregation parameters of dodecyldimethyl ethanolammonium bromide (C12DMEAB) surfactant on addition of Na-malate.

Silver, gold and silver–gold alloy nanoparticles were prepared in w/o microemulsion containing TritonX-100 and cyclohexane. Silver nitrate and tetrachloroauric(III) acid (HAuCl4) were taken as the metal precursors and sodium borohydride (NaBH4) was used as a reducing agent. The formation of Ag and Au nanoparticles was confirmed from the appearance of surface plasmon absorption maxima at 404 ± 2 and 525 ± 2 nm for Ag and Au nanoparticles, respectively. For bimetallic nanoparticles absorption peak was observed between the two maximas of corresponding metallic particles. The surface plasmon absorption maxima for bimetallic nanoparticles changes linearly with increasing Au mole ratio content in various alloy compositions. The transmission electron microscopy (TEM) showed formation of particles of 5–50 nm diameter. Dynamic light scattering (DLS) data gave narrow particle size distribution.

Gold, silver and gold–silver alloy nanoparticles were prepared under mild conditions using microwave heating, polyacrylamide as a stabilizing agent and hydrazine hydrate as a reducing agent. The UV–vis spectroscopy revealed the formation of silver and gold nanoparticles by exhibiting surface plasmon absorption maxima at 410 and 548nm, respectively. For Au–Ag bimetallic particles the surface plasmon absorption maxima appeared in between the peaks corresponding to pure silver and pure gold. The surface plasmon absorption maxima for bimetallic nanoparticles changes linearly with increasing gold content in the alloy. Transmission electron micrograph (TEM) showed presence of spherical particles in the range of 5–50nm size.

Small angle neutron scattering and conductance measurements were carried out for understanding the behavior of mixed surfactant system containing novel hydroxylated gemini surfactant 12-4-12 MEA (where MEA is monoethanol amine) and its corresponding monomeric counterpart dodecyldimethylethanol ammonium bromide (C12DMEAB). Critical micelle concentration (cmc) and average degree of ionization (βave) of mixed micelle was determined from conductance data, where as aggregation number (N), effective fractional charge per monomer (α), equilibrium distance between the charged heads (d) and dimension of micelle (b/a) were determined from SANS data. cmc, βave and d values were observed to decrease significantly and N and b/a values were observed to increase with increasing mole fraction of 12-4-12 MEA surfactant in mixed micellar system. The Kraft temperature (kT), methyl methacrylate (MMA) solubilization capacity, foamability and foam stability of mixed surfactant systems were also examined.

Cationic gemini surfactants have been extensively studied in the recent past and the effect of chain length, spacer length and nature on aggregation behavior has been examined. But the effect of variation in head group polarity on micellization has not been examined. Hence, the effect of head group polarity of the butane-1,4-bis(dodecyldimethylammonium bromide) surfactants on aggregation properties is studied through conductance, surface tension, viscosity, and small-angle neutron scattering (SANS) measurements. The critical micellar concentration (cmc), average degree of micelle ionization (βave), minimum area per molecule of surfactant at air–water interface (Amin), surface excess concentration (Γmax) and Gibbs free energy change of micellization (ΔG°mic) of the surfactants were determined from conductance and surface tension data. The aggregation numbers (N), dimension of micelle (b/a), effective fractional charge per monomer (α) were determined from SANS and hydration of micelle (hm) from viscosity data. The increasing head group polarity of gemini surfactant having spacer chain length of 4 methylene units promotes micellar growth, leading to decrease in cmc, βave, ΔG°mic and increase in N and b/a. This is well supported by the observed increase in hydration (hm) of micelle with increase in aggregation number (N) and dimension (b/a) of micelle. The Kraft temperature (kT), foamability and foam stability as a function of head group polarity of gemini surfactants were also examined.

Poly (styrene-divinylbenzene-acrylic acid) nanoparticles were synthesized through microemulsion polymerization using a three component oil-in-water microemulsion containing sodium dodecylsulphate. Stable and transparent poly (styrene–DVB-acrylic acid) nanolatexes were produced. The latexes were characterized for particle size and number of particles by dynamic light scattering and TEM. The isolated products were characterized by IR. The particles were further used for the loading of Acryflavin drug. Acryflavin was selected as a model drug to understand the behavior of in-vitro drug release pattern at different pH in nanoparticles.

ABSTRACT The emulsion and microemulsion copolymerizations of partially water-soluble monomers ethylacrylate (EA) and methylmethacrylate (MMA) were studied with the water-soluble initiator KPS and the oil soluble initiator AIBN. On changing from an emulsion to microemulsion system the shift in relative contribution of the different phases involved in particle formation is expected to control the kinetic and colloidal parameters and hence the solid content and latex stability. This has been tested using the water-soluble initiator KPS and the oil-soluble initiator AIBN. The microemulsion system initiated with KPS resulted in a much higher particle size and lower particle stability, whereas the emulsion system initiated with KPS at identical reaction conditions resulted in a stable colloidal polymer particles of very low particle size at a higher solid content. On the contrary, AIBN-initiated microemulsion generated a stable nanolatex as compared to the emulsion system. The copolymers, isolated during the nucleation stage, were analyzed for their composition using 1H NMR and for their thermal properties using DSC.

Effect of variation in head group polarity on physicochemical properties of butane-1,4-bis(dodecyldimethylammonium bromide) surfactants has been examined through conductance, surface tension and viscosity measurements. The critical micellar concentration (cmc) was determined by surface tension and conductance measurements. Surface tension data was further used to determine the maximum surface excess concentration (Γmax), minimum area per molecule (Amin) at air/water interface and Gibb's free energy of adsorption (ΔG°ad). Effect of variation in head polarity on average degree of micelle ionization (αave), binding of counterions to the micelle (β) and thermodynamics of micellization was examined through conductance measurement. Effective Gibb's free energy (ΔG°eff) and cmc were observed to decrease with head group polarity indicating that increase in head group polarity favors micellization process as compared to adsorption at the air/water interface. The intrinsic viscosity (η) and hydration of micelle (hE) were observed to increase with polarity of head and decrease with temperature.

The porcine pancrease lipase was immobilized by entrapment in the beads of K-carrageenan and cured by treatment with polyethyleneimine (PEI) in the phosphate buffer. The retention of hydrolytic activity of lipase and compressive strength of the beads were examined. The activity of free and immobilized lipase was assessed by using olive oil as the substrate. The immobilized enzyme exhibited a little shift towards acidic pH for its optimal activity and retained 50% of its activity after 5cycles. When the enzyme concentration was kept constant and substrate concentration was varied the Km and Vmax were observed to be 0.18 × 10−2 and 0.10, and 0.10 × 10−2 and 0.09 respectively, for free and for entrapped enzymes. When the substrate concentration was kept constant and enzyme concentration was varied, the values of Km and Vmax were observed to be 0.19 × 10−7 and 0.41, and 0.18 × 10−7 and 0.41 for free and entrapped enzymes. Though this indicates that there is no conformational change during immobilization, it also shows that the reaction velocity depends on the concentration. Immobilized enzyme showed improved thermal and storage stability. Hydrolysis of olive oil in organic–aqueous two-phase system using fixed bed reactor was carried out and conditions were optimized. The enzyme in reactor retained 30% of its initial activity after 480min (12cycles).

The compatibility of blends of starch cinnamate (StCn) with polyvinyl chloride (PVC), polystyrene (PS), and styrene acrylonitrile copolymer (SAN) has been examined through viscometry at 30°C. The results of the three systems are compared with the already reported PMMA/StCn system. From the intrinsic viscosity, relative viscosity, reduced viscosity, and density measurements the PVC/StCn and SAN/StCn blends were found to be compatible while PS/StCn blend was found to be incompatible. The compatibility of the blends was also confirmed by SEM analysis. The compatibility of these blends based on heat of mixing and polymer-polymer interaction parameter was also examined. Blends were observed to be compatible on the basis of heat of mixing theory but not on the basis of polymer - polymer interaction parameters. Biodegradation studies of compatible blends containing 30% StCn showed 13%, 15%, 18%, and 23% weight loss in case of PMMA, SAN, and PVC blends after 120 days. Keywords: BlendMiscibilityViscosityInteraction ParameterBiodegradability