S. Rajesh Kumar

Quercetin conjugated superparamagnetic magnetite nanoparticles for in-vitro analysis of breast cancer cell lines for chemotherapy applications

The magnetic nanoparticles attract increasing interest due to their opportunities in cancer therapy and used as drug carriers for several other diseases. The present study investigates the quercetin conjugated superparamagnetic Fe3O4 nanoparticles for in-vitro analysis of breast cancer cell lines for chemotherapy. A simple precipitation method was used to prepare the dextran coated Fe3O4 nanoparticles and the anticancer flavonoid quercetin was conjugated on the surface via carboxylic/amine group using nanoprecipitation method. The structural, morphological and the magnetic properties of the prepared materials were studied by using X-ray diffractometer (XRD), Fourier transformed infer-red spectrometer (FTIR), transmission electron microscope (TEM) and vibrating sample magnetometer (VSM). The MTT (3-(4,5-dimethylthiahiazol-2-yl)-2,5-diphenyl tetrazolium) assay of dextran coated Fe3O4 nanoparticles did not exhibit notable toxicity against MCF7 cells, whereas the cytotoxicity of quercetin conjugated Fe3O4 nanoparticles increased significantly in comparison with pure quercetin. The incubation of MCF-7 cells with quercetin conjugated Fe3O4 nanoparticles (QCMNPs) shows significant changes in cellular morphology observed through fluorescent microscopy. The results validate the prepared quercetin conjugated Fe3O4 nanoparticles are promising anticancer agents for targeted drug delivery.

Epoxy benzoxazine based ternary systems of improved thermo-mechanical behavior for structural composite applications

Ternary mixtures of various ratios of bisphenol F benzoxazine as a hardener for bisphenol F novolac epoxy (ER) and diglycidal ether of polyethylene glycol (EL) resins were made in order to study the visco elastic and thermo mechanical properties in comparison with homo polymerized polybenzoxazine (F-a). FTIR, and DSC were used to characterize the cure characteristic. The dynamic mechanical analyzer and thermo gravimetric analysis were investigated on F-a and ternary samples. An improved Tg of curable ternary mixture with 48.1 and 3.1 wt% of ER and EL respectively with benzoxazine resin was achieved based on trends in the ternary diagram. The ternary samples were thermally stable up to 370 °C when compared to F-a. Investigation of fracture toughness and SEM images showed improved fracture toughness for the samples with 52% binary epoxy mixture in the ternary system. The newly developed ternary mixtures showed improved service temperature, thermal stability, cross linking density, processing window and fracture toughness with minimum brittleness when compared to polybenzoxazine. The applicability of the developed ternary mixture was demonstrated by preparing an S glass fabric reinforced composite with F-f. It was observed that this S glass fabric composite has improved flexural strength, flexural modulus, ILSS, Shore D hardness & hydrolytic stability when compared to the polybenzoxazine composite and was found to be very useful for high performance structural applications.

Hydrophilic polymer coated monodispersed Fe3O4 nanostructures and their cytotoxicity

Surface functionalized monodispersed Fe3O4 magnetic nanoparticles were synthesized by the polyol method. Surfactants were used to control size, shape and agglomeration of the magnetic nanoparticles during the preparation. The size of these nanoparticles was in the range of 10–30 nm as observed in transmission electron microscopy (TEM). The formation of monodispersed shapes was controlled by varying the surfactants without changing the reaction conditions. The x-ray diffraction (XRD) pattern validates the phase purity and cubic structure even after the addition of surfactants. The functional groups were observed from Fourier transform infrared (FTIR) spectroscopy analysis, confirming the surface modification with polymer molecules in the polyol medium. The saturation magnetization value decreases from 89 to 59 emu g−1 for the surfactant coated Fe3O4 nanoparticles and it also shows superparamagnetic behavior at room temperature. Cell viability rate and percentage of dead cells were accurately identified in human breast carcinoma cell lines using in vitro cell viability experiments, which confirms that pristine and surfactant coated Fe3O4 nanoparticles are non-toxic and can be used for biomedical applications.

An in vitro analysis of H1N1 viral inhibition using polymer coated superparamagnetic Fe3O4 nanoparticles

Monodispersed Fe3O4 nanoparticles were prepared by a polyol assisted solvothermal method and their activity against H1N1 influenza A virus was studied. The present study also elucidates the influence of size, shape and surface properties of the pristine, as well as polymer coated, magnetite nanoparticles. X-ray diffraction and Fourier transform infrared spectroscopic observations confirm the high crystallinity and the polymer attachment with the magnetite nanoparticles. Transmission electron microscopy (TEM) images confirm the monodispersed nanoprisms and flower like morphologies of the magnetite nanoparticles. The superparamagnetic behavior and other magnetic properties were also studied by measuring the hysteresis loop using a vibrating sample magnetometer. The cell viability studies of the magnetite nanoparticles using a standard MTT assay confirm the non-toxic nature of the samples. Reverse transcription polymerase chain reaction (RT-PCR) analysis confirms the Fe3O4 nanoparticles inhibit influenza viral RNA synthesis in MDCK cells.

A new approach with prepregs for reinforcing nitrile rubber with phenolic and benzoxazine resins

Acrylonitrile-co-butadiene rubbers (NBR) reinforced with phenolic and benzoxazine resins (NBR–Ph and NBR–Bz respectively) are prepared by a novel method using co-curing. The relative effect of these resin reinforcements with NBR in comparison to the non-reinforced NBR rubber compound NBR–S under the same conditions has been investigated. It was found that these resins exist in the form of a localized, interpenetrating network structure in the NBR matrix. For both NBR–Ph and NBR–Bz composites, the tensile strength, tear strength and elongation at break increases compared to NBR–S. The tensile strength in particular was increased by about 91% for NBR–Ph and by about 109% for NBR–Bz. Thermogravimetric analysis (TGA) provides evidence for the superior thermal stability for NBR composites over NBR–S. A decrease in the swelling values are observed in the NBR composites and the retained tensile strength, elongation at break and modulus from thermal aging studies are found to be superior than NBR–S. These results have shown that both the phenolic and benzoxazine resins are effective reinforcements for NBR materials.

Facile synthesis of yeast cross-linked Fe3O4 nanoadsorbents for efficient removal of aquatic environment contaminated with As(V)

A facile solvothermal method was adopted to prepare monodispersed surface functionalized Fe3O4 nanoparticles via self assembly process. The pure yeast, diethylamine functionalized Fe3O4 nanoparticles (DMNPs) and yeast cross-linked Fe3O4 nanoparticles (YcMNPs) were used for the efficient removal of arsenate from aqueous solution. The crystal structure, morphology and magnetic properties of these nanoparticles were characterized by using X-ray diffraction, field emission scanning electron microscopy and vibrating sample magnetometer. The observed physico-chemical properties confirms the metal binding nature of prepared samples. The adsorption of As(V) on the functionalized magnetite nanoparticles was tested under different operating conditions like contact time, adsorbate dosage, adsorbate concentration and pH. The faster removal of As(V) was obtained using YcMNPs (99%) than DMNPs and pure yeast. The adsorption equilibrium data obeys Langmuir isotherm than Freundlich model and the kinetics data well depicts the pseudo-second-order model. The batch column experiment confirms the adequate desorption as well as reusability without significant loss of efficiency. The results reveal the technical feasibility of the prepared nanoparticles for their easy synthesis, recovery, cost effective, eco-friendly and a promising advanced adsorbent for environmental pollution.

Novel E glass composites with polybenzoxazine and in situ generating reactive multi branched titanate for low temperature cure and high thermal resistance applications

A new class of E glass fabric reinforced polybenzoxazine titanate composites (EBTA) were made with bisphenol F benzoxazine (BZ) and in situ generating reactive multi branched n-butoxy triethanol amine titanate (TEA) chelate in various ratios. The incorporation of TEA into a polybenzoxazine matrix could cause uniform dispersion within the polymer matrix and ring opening of oxazine at lower temperature, which result in an increase of the cross link density, stiffness and hindered network structures responsible for enhancing the thermal and water resistance. The hypothetical chemical reaction between BZ and TEA was understood by studying the reaction between model compounds such as phenol, tetra isobutyl titanate and triethanol amine. FTIR and DSC studies were utilized to optimize the curing studies and the final cure temperature was established for EBTA composites. The DMA analysis carried out on EBTA composites showed improved stiffness, crosslink density and service temperatures (Tg) with uniform phase distribution when compared to the E glass fabric reinforced polybenzoxazine composite. The thermal stability and char yield with TGA analysis, interfacial adhesion with SEM and hydrolytic stability for the EBTA composites using up to 23% of TEA were found to be improved when compared to the polybenzoxazine composite. The flame retardancy of EBTA composites were found to be retained for the V1 class of polybenzoxazine composite. The EBTA composites showed low maximum cure temperature, improved service temperature, cross link density, stiffness, water absorption resistance, thermal stability and char yield when compared to the E glass fabric polybenzoxazine composite.

Novel glass fabric-reinforced polybenzoxazine–silicate composites with polyvinyl butyral for high service temperature applications

The aim of this study is to develop novel glass fabric-reinforced polybenzoxazine–silicate composites with enhanced performances, which can overcome the disadvantages related to the low crosslink density of glass fabric-reinforced polybenzoxazine composites. Glass polybenzoxazine silicate composites were prepared via the copolymerization of bisphenol F benzoxazine using glass fabric, polyvinyl butyral as the coupling agent and various ratios of ethyl silicate. FTIR and DSC were utilized to study the chemical reactions and curing optimization, respectively. It was found that complete polymerization occurred at 200 °C. DMA analysis of the prepared glass polybenzoxazine silicate composites showed enhanced stiffness, crosslink density, service temperature, and network branching with uniform phase distribution. The thermal oxidative decomposition temperatures and char yield obtained by TGA and interfacial adhesion by SEM for glass polybenzoxazine silicate composites were found to be improved when compared to that of the glass polybenzoxazine composites. The composites prepared by this method showed enhanced service temperature, stiffness, crosslink density, thermal oxidative resistance, and char yield when compared to glass fabric-reinforced homopolymerized polybenzoxazine composites. These newly developed glass polybenzoxazine silicate composites are promising materials to overcome various shortcomings associated with polybenzoxazine and other traditional resin composites.