Polymer Nano Research Articles

Hollow polymeric (PLGA) nano capsules synthesized using solvent emulsion evaporation method for enhanced drug encapsulation and release efficiency

Nano-hollow polymer shells, especially those polymers which are FDA approved, have captured the attention of many researchers and scientists in the field of pharmaceutical and medical therapeutics. In the field of controlled drug/gene release, nano-capsules in colloidal solutions, i.e. particles with hollow piths, play an important role in cargo encapsulation. These nanoparticles are synthesized using a variety of procedures such as emulsion polymerization, phase separation, crosslinking of micelles, inner core etching and self-assembly. Our work proposes a novel route to prepare hollow PLGA (poly (lactic-co-glycolic) acid) nanoparticles (HNPs), which showed increased drug-encapsulation and release efficiency. The simple emulsion solvent evaporation technique was adopted to synthesize nano-hollow shells of FDA approved polymer PLGA using only one organic phase. The hollow characteristics of nanoparticles were studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and confocal microscopy analysis. The particle size was analyzed by dynamic light scattering (DLS). Nanoparticles drug loading, encapsulation and release efficiency in vitro were assessed by ultraviolet spectroscopy. The developed nanoparticles were hollow and spherical in shape and approximately 80 nm in size. The drug encapsulation efficiency is 99.4% and the drug was released in a controllable manner during in vitro analysis.

Highly stable polymer coated nano-clustered silver plates: a multimodal optical contrast agent for biomedical imaging

Here, we present a new optical contrast agent based on silver nanoplate clusters embedded inside of a polymer nano matrix. Unlike nanosphere clusters, which have been well studied, nanoplate clusters have unique properties due to the different possible orientations of interaction between the individual plates, resulting in a significant broadening of the absorption spectra. These nanoclusters were immobilized inside of a polymer cladding so as to maintain their stability and optical properties under in vivo conditions. The polymer-coated silver nanoplate clusters show a lower toxicity compared to the uncoated nanoparticles. At high nanoparticle concentrations, cell death occurs mostly due to apoptosis. These nanoparticles were used for targeted fluorescence imaging in a rat glioma cell line by incorporating a fluorescent dye into the matrix, followed by conjugation of a tumor targeting an F3 peptide. We further used these nanoparticles as photoacoustic contrast agents in vivo to enhance the contrast of the vasculature structures in a rat ear model. We observed a contrast enhancement of over 90% following the nanoparticle injection. It is also shown that these NPs can serve as efficient contrast agents, with specific targeting abilities for broadband multimodal imaging that are usable for diagnostic applications and that extend into use as therapeutic agents as well.

Assessment of nano dielectrics interface charge by electrokinetic sonic amplitude and atom force microscopy

Research has predicted the existence of the interface charges between nano particles and matrix polymers in nano dielectrics, which may become a dominant factor as the electrical properties of composites continue to improve. But until now, no experimental evidence has been found to prove this prediction. This research try to prove that the charging abilities of the nano particles in liquid suspension are related to that of polymeric nanocomposites, even more to find the existence evidence of interface charge in polymeric nanocomposites. Zeta potential of surface modified nano particles SiO 2 , and MgO/ paraffinic wax suspension systems have been measured by electrokinetic sonic amplitude (ESA) method to assess the charging properties. The average of zeta potential value of -62.8 mV and 2.1 mV of SiO 2 , and MgO/ wax suspension systems were obtained. The interface charge domains were detected by means of atomic force microscopy (AFM) lift model phase scanning of atomic flat surface of the corresponding polymeric nano composites. The interface charge domains have been found in SiO 2 / low density polyethylene (LDPE) nanocomposite but cannot be found in MgO/LDPE system, which agree with the tremendous deference of zeta potential of corresponding suspension. Three types of models are proposed to interpret the AFM phase scanning appearance of the domains. Measurement results of zeta potential and AFM phase scanning and j (current density)-E (electric field) characteristics of LDPE and two kinds of nano composites reveal that the interface charge zones would inhibit the conducting current densities of the composites, and the larger absolute value of zeta potential corresponds to the stronger inhibiting ability to the conducting current density in polymeric nanocomposites.

Mixing effect on emulsion polymerization in a batch reactor

The emulsion polymerization of methyl methacrylate (MMA) was carried out in a lab‐scale reactor, which was equipped with a pitched blade turbine, four baffles, a U shaped cooling coil, and a temperature controller. Potassium persulfate was used as the initiator and sodium dodecyl sulfate as the surfactant. The effects of impeller speed, mounting baffles, and reaction temperature on the monomer conversion, polymer nano particle size and number, and molecular weight were examined in detail. An increase in the impeller speed up to 250 rpm enhanced the polymer properties but further agitation reduced the conversion, particle size, and molecular weight. The installation of the baffles enhanced the particle size and molecular weight but reduced the conversion and particle number. The use of baffles resulted in a narrower size distribution throughout the polymerization process. While the particle size and molecular weight were reduced with an increase in the reaction temperature, the monomer conversion and particle number were improved. POLYM. ENG. SCI., 55:945–956, 2015. © 2014 Society of Plastics Engineers

Experimental Investigation on Dielectric and Thermal Characteristics of Nanosized Alumina Filler Added Polyimide Enamel

The polymer nano composite possess good priority recently for engineering applications. Especially the electrical insulating materials attract the high performance of nano composites. In this work the ballmill synthesiation process of nano sized Alumina (Al2O3), the preparation of new nano composite material with an content of enamel and synthesized Alumina as 1wt%, 3wt% and 5wt%. Experimental investigation has been carried out for the prepared nano composites materials with respect to dielectric parameter measurements such as dielectric loss (tan δ), dielectric constant (e), dielectric strength under various temperature. The partial discharge level also measured for all the samples and the PD inception voltage is also observed and compared. Weight loss of the material has been analyzed through TGA. It has been experimentally proved that 3wt% of Alumina nano filler added enamel has significant improvement in the dielectric and thermal properties.

Biocompatible nano-micro-particles by solvent evaporation from multiple emulsions technique

In this study, a method based on a multiple emulsions system was developed for the production of polymeric nano and micro-vectors. The possibility to apply an unified preparation technique to different polymers, such as polyesters [polycaprolactone, poly-dl-lactide, poly(dl-lactide-co-caprolactone) = 70/30] and polyacrylates [poly(methylmethacrylate–acrylic acid) = 73/27], loaded with different model molecules (budesonide, tamoxifen, and α-tocopherol) was explored. After selecting the best operating conditions, especially for emulsification and separation, the technique proved to be readily adaptable for production of both nano and micro-particles with different morphologies, depending on type of polymer, and consequently on solvent used for solubilization: nano-particles, with a round shape and a smooth surface, for polyesters, otherwise micro-particles for the polyacrylate polymer, owing to the presence of hydrophilic co-solvents, that caused both an easy coalescence between the oil and water phases, thus enlarged particles size, and a high porosity. Even the yield of encapsulation was influenced by the presence of hydrophilic co-solvents, causing a higher yield for nano-vectors. Polyesters-based nano-vectors showed release times of molecules, linked to their degradation time, higher than 8 months that make them useful to formulate injectable or implantable drug delivery systems. Polyacrylate-based micro-vectors showed an enteric behavior, interesting for designing solid pharmaceutical formulations for oral delivery. Therefore, the technique demonstrated to assure a broad application in drug delivery research.

Porous silicon-cyclodextrin based polymer composites for drug delivery applications

One of the main applications of porous silicon (PSi) in biomedicine is drug release, either as a single material or as a part of a composite. PSi composites are attractive candidates for drug delivery systems because they can display new chemical and physical characteristics, which are not exhibited by the individual constituents alone. Since cyclodextrin-based polymers have been proven efficient materials for drug delivery, in this work β-cyclodextrin–citric acid in-situ polymerization was used to functionalize two kinds of PSi (nanoporous and macroporous). The synthesized composites were characterized by microscopy techniques (SEM and AFM), physicochemical methods (ATR-FTIR, XPS, water contact angle, TGA and TBO titration) and a preliminary biological assay was performed. Both systems were tested as drug delivery platforms with two different model drugs, namely, ciprofloxacin (an antibiotic) and prednisolone (an anti-inflammatory), in two different media: pure water and PBS solution. Results show that both kinds of PSi/β-cyclodextrin–citric acid polymer composites, nano- and macro-, provide enhanced release control for drug delivery applications than non-functionalized PSi samples.

Development of methods for encapsulation of viruses into polymeric nano‐ and microparticles for aquaculture vaccines

ABSTRACTTo meet an urgent need for improved vaccines against viral diseases in aquaculture, encapsulating the viruses into biodegradable and biocompatible polymers was suggested to protect viral antigens from premature degradation and gradually expose them to the immune system. We used water‐in‐oil‐in‐water emulsion to first encapsulate model red fluorescent polystyrene (PS) particles and then infectious salmon anemia virus (ISAV) into poly‐lactic‐co‐glycolic acid (PLGA) together with coumarin 6. A milder layer‐by‐layer method was applied to incorporate both PS and ISAV into chitosan (Cs)‐fluorescein isothiocyanate and alginate (Alg) followed by ionic crosslinking. All particles were characterized by dynamic light scattering, zeta‐sizer, fluorescence, transmission‐ and scanning electron microscopy. Successful encapsulation of PS beads and ISAV into PLGA, Cs, and Alg was accomplished. The prepared particles were of different size, surface charge density, and morphology. This yields opportunities for further developments of these structures as vaccine candidates to be delivered by injection or oral administration. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40714.

Synthesis and characterizations of Fe3O4-acid fuchsin tagged poly(ϵ-caprolactone) nanocomposites

Ring opening polymerization (ROP) of caprolactone (CL) was carried out at different experimental conditions such as variation in [M], [M/I] and temperature under N2 atmosphere at 160 °C for 2 h with mild stirring condition by using acid fuchsin (AF) decorated Fe3O4 as a novel chemical initiator with the aid of stannous octoate as an effective catalyst. Thus, prepared polymer nano composite samples were characterised by various analytical techniques such as Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, UV-visible spectroscopy, fluorescence spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), gel permeation chromatography (GPC), vibrating sample measurement (VSM), scanning electron microscopy (SEM) and field emission scanning electron microscopy (FESEM). Presence of Fe2p and Fe3p was confirmed by x-ray photoelectron spectroscopy (XPS) analysis. It was found that while increasing the [M/I] the melt transition values were increased. The surface catalytic effect of Fe3O4/AF hybrid system towards the ROP of CL was also studied.

Preparation and characterization of CuI/PVA–PEDOT:PSS core–shell for photovoltaic application

In the present paper nano polymer composite of CuI/PVA blended with PEDOT:PSS has been prepared by growing CuI nano particles inside aqueous solution of PVA. The XRD characterization illustrated the growth of CuI nano crystals of 22–33nm. The optical absorption showed direct transition with an energy band gap equals to 1.18eV and 1.3eV for colloidal and thin solid films respectively. The PL investigation illustrates a quenching with increasing PEDDOT:PSS concentration. The results are interpreted according to energy confinement enhanced by plasmon–exciton interaction of CuI–PVA/PEDOT:PSS core–shell. The frequency dependence of conductivity suggested hopping conduction where the bulk conductivity is thermally activated with an activation energy in the range varies from 0.07 to 0.46eV by increasing PEDOT:PSS concentration. The cyclic voltammetry measurements have been performed to ascertain the position of both HOMO and LUMO levels which illustrated a movement of HOMO level toward vacuum level, with a decrease in the chemical band gap from 1.72 to 1.3eV with increasing PEDOT:PSS concentration.

Development of Polymeric Nanopaclitaxel and Comparison with Free Paclitaxel for Effects on Cell Proliferation of MCF-7 and B16F0 Carcinoma Cells

Paclitaxel is hydrophobic in nature and is recognized as a highly toxic anticancer drug, showing adverse effects in normal body sites. In this study, we developed a polymeric nano drug carrier for safe delivery of the paclitaxel to the cancer that releases the drug in a sustained manner and reduces side effects. N-isopropylacrylamide/ vinyl pyrrolidone (NIPAAm/VP) nanoparticles were synthesized by radical polymerization. Physico- chemical characterization of the polymeric nanoparticles was conducted using dynamic light scattering, transmission electron microscopy, scanning electron microscopy and nuclear magnetic resonance, which confirmed polymerization of formulated nanoparticles. Drug release was assessed using a spectrophotometer and cell viability assays were carried out on the MCF-7 breast cancer and B16F0 skin cancer cell lines. NIPAAm/ VP nanoparticles demonstrated a size distribution in the 65-108 nm range and surface charge measured -15.4 mV. SEM showed the nanoparticles to be spherical in shape with a slow drug release of ~70% in PBS at 38° over 96 h. Drug loaded nanoparticles were associated with increased viability of MCF-7 and B16F0 cells in comparison to free paclitaxel. Nano loaded paclitaxel shows high therapeutic efficiency by sustained release action for the longer period of time, i increasing its efficacy and biocompatibility for human cancer therapy. Therefore, paclitaxel loaded (NIPAAm/VP) nanoparticles may provide opportunities to expand delivery of the drug for clinical selection.

Second blows in the head-on collisions of spherical nano polymer droplets

We report observations of a weird but interesting phenomenon from molecular dynamics simulations: the occurrence of second blows in head-on collisions of two equal-sized spherical nano polymer droplets. In head-on collisions, we usually expect single-peak impact forces between the two colliding droplets. However, a second peak of the impact force is actually observed in the simulations. Its underlying mechanisms on a molecular scale are proposed.

A new solder matrix nano polymer composite for thermal management applications

The increasing integration of microelectronics, raising the need for effective heat dissipation, requires new and improved composite materials technologies. For both thermal interface and die attach materials, a major challenge is to combine low thermal resistance joints with sufficient thermomechanical decoupling and reliability. In this paper, we present the fabrication and characterisation of a new type of solder matrix nano polymer composite (SMNPC) aiming to address these challenges. The SMNPC is fabricated into preforms by liquid-phase infiltration of a Sn–Ag–Cu matrix into a silver nanoparticle coated electrospun polyimide fibre mesh. The composite is demonstrated to possess high heat transfer capability, close to that of a direct soldered interface, lower elastic modulus compared to pure Sn–Ag–Cu alloy, and reliable thermomechanical performance during thermal cycling. Taken together, the results indicate that the developed SMNPC can be a useful composite alternative compared to conventional solders and polymer matrix materials for thermal management applications.

Conformation and Structure of Bio Polymer Nano Particle Formed by β-Lactoglobulin-Pectin in the Presence of Sorbitol

Aims: This research investigates the influences of low methoxyl pectin (LMP) and sorbitol on the morphology and secondary structure of beta-lactoglobulin (BLG). Methodology: The effects of pH and temperature on the structure of the nano-complexes containing BLG, BLG-LMP and BLG-LMP in the presence of co-solvent (sorbitol) were studied by means of a far-UV Circular Dichroism spectroscopy (CD) and the size and morphology of nano-complexes measured by particle size analyzers, Scanning Electron Microscope (SEM) and Transmission Electron Microscopy (TEM). Results: CD results at different pH levels (4, 4.5, 5.3 and 6.3) indicated that the structural changes of BLG were more pronounced relative to BLG-LMP and BLG-LMP in presence of sorbitol. However, less destruction faced the protein structure at pH 5.3 compared to pH 4.5 and 4, therefore pH 5.3 was selected. BLG-LMP in presence of sorbitol had more protective effects on the secondary structure and indicated a high thermal stability when heated up to 75oC for 10 minutes. Particle size measurement revealed that the size of BLG aggregate was as much as 250 nm while the BLG-LMP size in presence of sorbitol nanocomplex was around 100 nm. SEM and TEM observations indicated uniform and spherical nano-complexes. Conclusion: The treated bio polymer particles have suitable properties and great potential as carriers for encapsulation and delivery of bio-active materials as well as a substitution Research Article British Journal of Applied Science & Technology, 3(4): 1144-1161, 2013 1145 for lipid droplets.

Controlled synthesis and characterization of core-shell fluoro-silicone-containing fabric agent

The core-shell particles containing fluorine-silicon polymer was prepared by activators regenerated by electron transfer atom transfer radical polymerization(ARGET-ATRP)using SiO2-Br as initiator.The obtained polymer with well-controlled molecular weight and low polydispersity was used as water and oil repellent fabric finishing agent.Kinetics of the polymerization showed the polymerization was a living/controlled system.Characterization of FT-IR,1 H NMR,19 F NMR,XPS,TEM confirmed the core-shell structure of the polymer and the presence of F element.The formation of dual micro-nano structure between nano polymer and the surface of fabric enhanced the water and oil repellency of the cotton fabric.

Overview on in Polymer-Nano Clay Composite Paper Coating for Packaging Application

This is a review of the existing studies on the Polymer/ clay nano composite used for improving water and moisture barrier in coating. Clays have been and continue to be one of the more important industrial minerals. Research and development activities by clay scientists in academia, government, and industry are continually resulting in new and innovative clay products many of these new applications are the result of improved processing which provides clays of higher purity, more precise particle size and distribution, whiter and brighter color, modified surface chemistry, and other physical and chemical modifications. Some new and improved clay products include tailored or engineered paper coating kaolins, nanocomposites for plastics etc. The use of mineral pigments in coating to provide improved barrier properties has recently gaining increased attention. I described the use of Polymer nano clay for improving the barrier properties of the coated paper studied by several researchers.

Static Behaviour of Visco-elastic Sandwich Plate with Nano-composite Facings under Mechanical Load

Static behaviour of visco-elastic sandwich plate with functionally graded carbon nano tube reinforced polymer nano composite facings has been analyzed using finite element method. Parameter studies have been carried out to analyze influence of volume fraction of carbon nanotube (CNT), nature of functional grading of CNT, core material and core thickness to facing layer thickness ratio on static bending deflection, axial stress and transverse shear stresses of the plate under mechanical load. It is found that functional grading of CNTs in FG-X pattern enhances the static characteristics compare to uniform distribution of CNTs. It is found that maximum static bending deflection of the visco-elastic plate decreases with increase in volume fraction of CNTs. Influence of visco-elastic core thickness and visco-elastic core material on static characteristics is significant.

Y-shaped block copolymer (methoxy-poly(ethylene glycol))2-b-poly(l-glutamic acid): preparation, self-assembly, and use as drug carriers

The nano polymer drugs based on Y-shaped block copolymer mPEG2-PGA show a great potential on the treatment for solid tumors.

Cross-Linked Polysaccharide Assemblies in Marine Gels: An Atomistic Simulation

Marine polymeric gels or colloidal nano- and microgels have been shown to contribute significantly to the primary marine aerosol and cloud condensation nuclei over remote marine areas. A microscopic understanding of such biologically derived matter at the sea–air interface is important for future development of global climate models, but unfortunately cannot be obtained from modern characterization techniques. In this contribution, we employ molecular dynamics simulations to reveal the atomistic details of marine polymeric gels represented by anionic polysaccharide assemblies. The ionic bonds formed between polysaccharides and metal ions in seawater as well as the hydrophobic contribution to surface area are investigated in detail, and destabilization of the assemblies upon removal of Ca2+ or acidification is explained. These results provide insight into physicochemical properties of polysaccharide–Ca2+ structures and enable future studies of their roles of in the wetting process of cloud droplet activation.

Engineering Polymeric Microparticles as Theranostic Carriers for Selective Delivery and Cancer Therapy

Multifunctional polymeric nano- and microparticles are engineered as theranostic carriers and their selective size-dependent cellular uptake is demonstrated. It is found that effective uptake and accumulation of nanoparticles occurs in both normal and cancer cells, whereas, that of microparticles occurs in cancer cells but not in normal cells, allowing cancer cells to be specifically targeted for local drug delivery.