Free Radical Grafting Reaction Research Articles

Grafting of voltage stabilizer onto EPDM surface and its inhibition effect on the breakdown of EPDM/XLPE interface

Surface discharge on the EPDM/XLPE interface is threatening the safe operation of power cable system and limiting the further improvement of its voltage level. To improve the electrical strength of EPDM/XLPE interface, the surface of EPDM was modified by grafting of voltage stabilizer 4-allyloxy-2-hydroxybenzophenone (AOHBP) based on liquid-phase impregnation and subsequent free radical grafting reaction thermally initiated by DCP. EPDM samples were modified by mixed reagents of DCP and AOHBP with different mass ratios of 1:2, 1:3 and 1:4, respectively. The SEM observation and XRD analysis results indicate that the crystals of AOHBP with a uniform distribution are covered on the surface of EPDM during the sample preparation process and then dissolved after extraction by acetone. The FTIR and ATR results show that the AOHBP molecules are successfully grafted onto the surface of EPDM samples, but there remain a lot of ungrafted reagent molecules on the surface of EPDM before solvent extraction. The grafting rate of AOHBP increases with the proportion of DCP in the mixed reagents. As for the unextracted modified EPDM samples, both the AC and DC breakdown voltage of the EPDM/XLPE interface are increased compared with pure EPDM, and further increased after the ungrafted molecules are extracted because the effect of voltage stabilizer on scavenging high-energy electrons is more efficiently utilized at a smoother interface. The interface breakdown voltage of the sample modified with 1:2 mass ratio of DCP/AOHBP mixed solution is the highest because of its highest grafting rate of voltage stabilizer. This work has proposed a new technical path to improve the electrical aging resistance of polymer insulating surface.

A versatile food packaging film fabricated by gallic acid/octanoic acid grafted chitosan: Preparation, characterization, high-efficient cells capture and photodynamic eradication of bacteria and biofilms

This study aims to construct a versatile film fabricated by gallic acid/octanoic acid-grafted-chitosan (GA/OA-g-CS) for high photodynamic antibacterial and antibiofilm efficacy with blue light (BL, 420 nm) irradiation. First, the GA/OA-g-CS conjugates were synthesized by a green radical-induced grafting reaction in the redox system composed of ascorbic acid/hydroxyl peroxide (AA/H2O2). Then, the molecular structural and physicochemical characteristics of the conjugates, as well as the mechanisms of the free radical grafting reaction were further studied. Ascorbate radical (Asc•−) and hydroxyl radical (•OH) were produced in the AA/H2O2 system, and •OH reacted with CS to produce CS macro-radicals (•CS). UV–vis, Fourier transform infrared, nuclear magnetic resonance spectroscopy, X-ray diffraction (XRD), and thermogravimetric analysis confirmed that GA/OA was attached onto CS through •OH. Notably, the films constructed by GA/OA-g-CS exhibited robust multi-modal functionalities, including intriguing bacteria-capturing and contact-killing, as well as BL-driven photodynamic sterilization, ascribed to the inherent merits based on the massive photoactive GA, hydrophobic and high membrane affinity of OA within the CS chains. As a result, the GA/OA-g-CS (2:1) film plus BL irradiation can efficiently eradicate Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) and their biofilms. After BL irradiation for 30 min, the GA/OA-g-CS (2:1) film showed a reduction of 5.2 Log CFU/mL against E. coli. More importantly, the film with BL irradiation can efficiently not only inhibit the formation of biofilms but also jeopardize the matured biofilms. This research provides a potential platform and promises for applications in active and intelligent food packaging.

Fabrication of durable and non-leaching triclosan-based antibacterial polypropylene

Despite achieving broadscale commercial applications, Polypropylene (PP) is prone to bacterial contamination, which poses huge threats to public health. Applying antibacterial agents in polymer matrix is recognized as a widespread method to endow PP biocidal properties. Herein, we report a preparation of triclosan (TCS) based antibacterial PP through free radical grafting. As the methyl acrylate group is introduced to the TCS in advance to synthesize a radical-active monomer (f), PP-f products are successfully prepared via two typical free radical grafting reactions, solution grafting (PP-f-sg) and melt grafting (PP-f-mg). Although showing high f content (up to 12.7 mol%), PP-f-sg samples are of low monomer utilization (less than 50%) and the grafting reaction must be assisted by comonomers. On the contrary, PP-f-mg samples with modest f content (from 0.08 to 0.34 mol%) reveal satisfying monomer efficiency (over 80%) without the help of any comonomers, which demonstrates significant advantages. When addition amount of f reaches 0.12 mol% (1.0 wt%), antibacterial rates (R) of PP-f exceed 99% against both E. coli and S. aureus. Since covalent bonds are formed between TCS and PP chains, the biocidal properties of PP-f are durable and non-leaching. The R of PP-f maintains over 90% after ethanol extraction, while those extracted samples made by physical blending of TCS and PP completely lose their antimicrobial properties.

Life cycle design of fully bio-based poly(lactic acid) composites with high flame retardancy, UV resistance, and degradation capacity

Polylactic acid (PLA) is flammable, susceptible to UV light, and slow during degradation in nature, which limits the expansion of its application fields. Herein, a multifunctional bioderived additive (PA@TA-CS) was prepared by free radical grafting reaction between chitosan (CS) and tannic acid (TA) with the coating of phytic acid (PA) to achieve an all-round improvement of PLA. Only 3%PA@TA-CS in PLA increased the LOI value to 26.9%, upgraded the UL-94 level to V-0, and blocked nearly 99% UV light. In addition, by the presence of PA@TA-CS, the degree of molecular chain scission caused by hydrolysis and microbial degradation was significantly intensified. This work inherited the idea of returning to nature from nature and provided an effective strategy for extending the service life of bioplastics . • A fully bio-based additive PA@TA-CS is designed and synthesized by an organic solvent-free method. • Incorporation of PA@TA-CS imparts a desirable UL-94 V-0 rating to PLA at low loading. • 3 wt%PA@TA-CS can endow PLA with excellent UV-resistance property. • PA@TA-CS accelerate the degradation rate of PLA, with the whole composite decomposing harmlessly in the soil.

Fabrication of chitosan-protocatechuic acid conjugates to inhibit lipid oxidation and improve the stability of β-carotene in Pickering emulsions: Effect of molecular weight of chitosan

In this study, chitosan (CS) with different molecular weights was functionalized with protocatechuic acid (PA) by free-radical grafting reaction, and used for the inhibition of lipid oxidation and the enhancement of stability of β-carotene in Pickering emulsions. The order of grafting ratio of PA in CS-PA conjugates was CS400 (400 kDa CS) > CS200 (200 kDa CS) > CS100 (100 kDa CS). UV–vis, FT-IR and 1H NMR spectra proved that PA was covalently bonded to CS through amino and ester linkages. Compared with native CS, three CS-PA conjugates exhibited reduced crystallinity and thermal stability and improved antioxidant activity, with a molecular weight-dependent relationship. Besides, CS-PA-conjugate particles formed by ionic gelling procedure were spherically shaped and homogeneously dispersed, which substantially improved the stability of β-carotene in Pickering emulsions than CS particles under ultraviolet irradiation, natural light exposure and heat treatment, and the retention rates of β-carotene were in the following order: CS200-PA- > CS400-PA- > CS100-PA-conjugate particles. Furthermore, the oxidation stability of Pickering emulsions fabricated by CS-PA-conjugate particles was also higher than that of CS particles. These results will provide valuable information for the application of CS-PA conjugates to protect bioactive components and inhibit lipid oxidation in emulsion systems.

The fabrication of novel zein and resveratrol covalent conjugates: Enhanced thermal stability, emulsifying and antioxidant properties

Novel zein and resveratrol conjugates were fabricated by alkaline and free radical grafting reactions. The grafting efficiency and total phenolic content of alkaline treated conjugates were slightly higher than those of free radical grafting. Compared to native and alkaline treated zein, the sulfhydryl contents of conjugates were obviously decreased, confirming that nucleophilic addition of resveratrol to sulfhydryl group of zein formed stable CS covalent bonds. The conformation changes of zein modified by resveratrol were revealed by fourier transform infrared spectroscopy and fluorescence spectroscopy. Moreover, covalent modification changed isoelectric point of zein from 6.5 to 5.4 (alkaline) or 5.6 (free radical grafting), and broadening the pH application range of zein. It was worth mentioning that the conjugates showed much higher thermal stability, antioxidant activity, and emulsify activity than those of native zein. This study provides an effective way for the design of novel delivery systems to encapsulate bioactive substances.

Polymer Ligands Derived from Jute Fiber for Heavy Metal Removal from Electroplating Wastewater.

Industrial operations, domestic and agricultural activities worldwide have had major problems with various contaminants caused by environmental pollution. Heavy metal pollution in wastewater also a prominent issue; therefore, a well built and economical treatment technology is demanded for pollution-free wastewater. The present work emphasized pure cellulose extracted from jute fiber and further modification was performed by a free radical grafting reaction, which resulted in poly(methyl acrylate) (PMA)-grafted cellulose and poly(acrylonitrile)-grafted cellulose. Subsequently, poly(hydroxamic acid) and poly(amidoxime) ligands were prepared from the PMA-grafted cellulose and PAN-grafted cellulose, respectively. An adsorption study was performed using the desired ligands with heavy metals such as copper, cobalt, chromium and nickel ions. The binding capacity (qe) with copper ions for poly(hydroxamic acid) is 352 mg g−1 whereas qe for poly(amidoxime) ligand it was exhibited as 310 mg g−1. Other metal ions (chromium, cobalt and nickel) show significance binding properties at pH 6. The Langmuir and Freundlich isotherm study was also performed. The Freundlich isotherm model showed good correlation coefficients for all metal ions, indicating that multiple-layers adsorption was occurred by the polymer ligands. The reusability was evaluated and the adsorbents can be reused for 7 cycles without significant loss of removal performance. Both ligands showed outstanding metals removal capacity from the industrial wastewater as such 98% of copper can be removed from electroplating wastewater and other metals (cobalt, chromium, nickel and lead) can also be removed up to 90%.

Dextran–Hesperetin Conjugate as a Novel Biocompatible Medicine for Antimicrobial and Anticancer Applications

Hesperidin (HD), a bioflavanone glycoside, was isolated from orange peel and converted to hesperetin (HT) using a simple and efficient green procedure. Then dextran-hesperetin conjugate (Dex-HT) was prepared by free radical grafting reaction and the functionalization degree of it was assessed by the Folin–Ciocalteu method. The antioxidant activity of HD, HT and Dex-HT was tested by DPPH⋅ radical method. Presence of dextran as a backbone in the Dex-HT structure, improved antioxidant activities of the hesperetin. In addition, antimicrobial effect of these compounds was evaluated against some food pathogens (Listeria monocytogenes and Salmonella typhimurium). According to the results, L. monocytogenes was more sensitive to these compounds than S. typhimurium. Also, Dex-HT was more bacteriostatic than HD and HT. In addition, cytotoxic effect of Dex-HT against MCF-7(human breast adenocarcinoma), AGS (gastric adenocarcinoma) and normal fibroblast cells was determined in 48 and 72 h using MTT assay. The outcomes indicated that Dex-HT induced a significant dose-dependent cytotoxic effect on both AGS and MCF-7 cells. Moreover, Dex-HT showed a greater cytotoxic effect on MCF-7 cells than on AGS and normal cells. In this study, dextran, a biodegradeble carbohydrate polymer, was employed as a versatile scaffold to develop highly efficient antioxidant, antibacterial and anticancer hybrid material.

Dextran-immobilized curcumin: An efficient agent against food pathogens and cancer cells

Curcumin–dextran conjugate was synthesized by free radical grafting reaction between curcumin and dextran. The chemical characterization of the conjugate was obtained by Fourier-transform infrared and 1H-NMR (proton nuclear magnetic resonance) spectroscopy analysis, while the functionalization degree was determined by the Folin–Ciocalteu assay, finding a 22.93 mg of curcumin/g of dextran conjugate. Antioxidant activity of curcumin and curcumin–dextran conjugate was investigated employing DPPH• radical method, and IC50 (the half maximal inhibitory concentration) values of curcumin and the curcumin–dextran conjugate (Cur equivalents) were 86.6 ± 0.1 and 17.4 ± 1 µM, respectively. The presence of dextran into the curcumin–dextran conjugate improved radical scavenging activities of the curcumin. In addition, antimicrobial effect of curcumin and curcumin–dextran conjugate was evaluated against gram-positive ( Listeria monocytogenes and Staphylococcus aureus) and gram-negative ( Escherichia coli O157:H7 and Salmonella typhimurium) bacteria. According to our experiments, gram-positive microorganisms are more sensitive to these compounds than gram-negative ones. Curcumin–dextran is a more potent bacteriostat ( S. aureus (minimum inhibitory concentration = 0.008 µg/mL), E. coli O157:H7 (minimum inhibitory concentration = 250 µg/mL), and S. typhimurium (minimum inhibitory concentration = 500 µg/mL)) and also a more potent bacteriosid against S. aureus and S. typhimurium than curcumin. The cytotoxic effects of the curcumin–dextran conjugate toward AGS, MCF-7, and normal fibroblast cell lines were determined at 48 and 72 h using an MTT assay. The results revealed the considerable antiproliferative effects of the curcumin–dextran conjugate in both AGS and MCF-7 cancer cells in comparison with fibroblast cells. This study shows that dextran as a versatile scaffold develops the biological activities of curcumin by covalent grafting and can be regarded in further bioapplications.

Numerical study of turbulent heat transfer of nanofluids containing eco-friendly treated carbon nanotubes through a concentric annular heat exchanger

In this study, we conducted numerical simulations using finite volume method to examine thermal and hydrodynamic characteristics of clove-treated multi-walled carbon nanotube (C-MWCNT)/distilled water nanofluids in a concentric annular heat exchanger exposed to uniform and constant heat flux boundary conditions. We devised an environmentally friendly functionalization method to synthesize the MWCNTs where the MWCNTs were covalently treated with clove buds in one pot using free radical grafting reaction for preparation of homogeneous MWCNT nanofluid without involving existing corrosive, hazardous acid based conventional functionalization methods of carbon nanomaterials. We analysed the C-MWCNTs using Fourier transform infrared spectroscopy in order to assess the surface modification of MWCNTs. Next, we performed numerical simulations in order to predict the convective heat transfer and hydrodynamic characteristics of the nanofluids considering three concentrations of C-MWCNTs: 0.075, 0.125, and 0.175 wt.%. The effective thermo-physical properties of the nanofluids, which we obtained experimentally, were used in our three-dimensional simulations in order to solve the governing equations of fluid dynamics (continuity, momentum and energy), along with the k-ω turbulence model. We found that there is a good agreement between the simulation and experimental results. We also noticed that the addition of a small fraction of C-MWCNTs into distilled water significantly enhances the convective heat transfer coefficient relative to distilled water. Our results are also encouraging because we observed that the friction factor does not vary significantly for the nanofluids at their concentration range. In general, we conclude that our simulation model can be used to predict the convective heat transfer and hydrodynamic characteristics of C-MWCNT/distilled water nanofluids in a concentric annular heat exchanger with reasonable accuracy and the results show the promising capabilities of these nanofluids as coolants.

CFD modeling of turbulent convection heat transfer of nanofluids containing green functionalized graphene nanoplatelets flowing in a horizontal tube: Comparison with experimental data

In this research, a series of numerical simulations were conducted utilizing computational fluid dynamics (CFD) software in order to predict the heat transfer performance of queues nanofluids containing clove-treated graphene nanoplatelets (CGNPs) flowing in a horizontal stainless steel heated pipe. The GNPs were covalently functionalized with clove buds using free radical grafting reaction using an eco-friendly process. The advantage of this synthesis method was that it did not use hazardous acids, which are typically used in traditional treatment methods of carbon nanostructures. The thermo-physical properties of the aqueous nanofluids obtained experimentally were used as inputs for the CFD simulations for solving the governing equations of heat transfer and fluid motion. The shear stress transport (SST) k-ω turbulence model was also used in these simulations. The corresponding convective heat transfer coefficient and friction factor of aqueous nanofluids for nanoparticle weight concentrations of 0.025, 0.075, and 0.1% were evaluated. The simulation results for both heat transfer coefficient and friction factor were shown to be in agreement with the experimental data with an average relative deviation of about ±10%. The presented results confirmed the applicability of the numerical model for simulating the heat transfer performance of CGNPs aqueous nanofluids in turbulent flow regimes.

Preparation, characterization, and functional evaluation of proanthocyanidin-chitosan conjugate

In this study, chitosan (CS) was conjugated with proanthocyanidin (PA) by a free radical grafting reaction. The successful synthesis of PA-CS conjugate was confirmed by Fourier transform infrared spectroscopy and proton nuclear magnetic resonance. The optimal molar ratio of PA to CS repeat unit for the preparation of PA-CS was 0.13:1, which led to a high PA content of 381.76 mg PAE/g in PA-CS. The antioxidant assays demonstrated that PA-CS had much stronger radical scavenging activity and reducing power than the native CS. Especially, the half-inhibition concentrations of PA-CS against DPPH and ABTS radicals were only 6.2 μg/mL and 5.9 μg/mL, respectively. In addition, PA-CS showed an alteration in antibacterial activity compared with CS, and the alteration varied with bacterial strain.

Reaction Mechanisms and Structural and Physicochemical Properties of Caffeic Acid Grafted Chitosan Synthesized in Ascorbic Acid and Hydroxyl Peroxide Redox System.

The ascorbic acid (AA) and hydroxyl peroxide (H2O2) redox pair induced free radical grafting reaction is a promising approach to conjugate phenolic groups with chitosan (CS). In order to reveal the exact mechanisms of the AA/H2O2 redox pair induced grafting reaction, free radicals generated in the AA/H2O2 redox system were compared with hydroxyl radical (•OH) produced in the Fe2+/H2O2 redox system. Moreover, the structural and physicochemical properties of caffeic acid grafted CS (CA-g-CS) synthesized in these two redox systems were compared. Results showed that only ascorbate radical (Asc•-) was produced in the AA/H2O2 system. The reaction between Asc•- and CS produced novel carbon-centered radicals, whereas no new free radicals were detected when •OH reacted with CS. Thin layer chromatography, UV-vis, Fourier transform infrared, and nuclear magnetic resonance spectroscopic analyses all confirmed that CA was successfully grafted onto CS through Asc•-. However, CA could be hardly grafted onto CS via •OH. CA-g-CS synthesized through Asc•- exhibited lower thermal stability and crystallinity than the reaction product obtained through •OH. For the first time, our results demonstrated that the synthesis of CA-g-CS in the AA/H2O2 redox system was mediated by Asc•- rather than •OH.

Curcumin loaded chitin-glucan quercetin conjugate: Synthesis, characterization, antioxidant, in vitro release study, and anticancer activity

In this study, we have synthesized chitin-glucan quercetin conjugate (ChGCQ) by an easy and facile free radical grafting reaction. The structure of ChGCQ was confirmed by proton nuclear magnetic resonance (1H NMR) and Fourier transforms infrared spectroscopy (FT-IR). Curcumin was loaded into ChGCQ to study its anti-cancer efficiency. The biocompatibility of ChGCQ and curcumin loaded ChGCQ (Cu-ChGCQ) were analysed by different assays in Peripheral blood mononuclear cells (PBMCs) and cytotoxicity test was performed in a macrophage cancer cell line (J774). The result shows tremendous biocompatibility of ChGCQ and Cu-ChGCQ in peripheral blood mononuclear cells and excellent cytotoxity in macrophage cancer cell line (J774). Chitin-glucan complex (ChGC), ChGCQ and Cu-ChGCQ showed 51%, 66% and 74% of DPPH radical-scavenging activity at 1mg/ml respectively, which are much higher than that of ChGC and in ABTS*+ assay 58%, 71% and 83% show radical-scavenging activity at 1mg/ml. Antioxidant assay of Cu-ChGCQ conjugate expressed much higher antioxidant activity than ChGCQ and ChGC. In vitro drug release study of Cu-ChGCQ conjuagate showed faster drug release in acidic medium in comparison to PBS of physiological pH and anticancer activity in vitro assay showed more anticancer activity of Cu-ChGCQ in comparison to ChGCQ conjugate.

Biodegradable biocomposites from poly(butylene adipate‐co‐terephthalate) and miscanthus: Preparation, compatibilization, and performance evaluation

ABSTRACTMiscanthus fibers reinforced biodegradable poly(butylene adipate‐co‐terephthalate) (PBAT) matrix‐based biocomposites were produced by melt processing. The performances of the produced PBAT/miscanthus composites were evaluated by means of mechanical, thermal, and morphological analysis. Compared to neat PBAT, the flexural strength, flexural modulus, storage modulus, and tensile modulus were increased after the addition of miscanthus fibers into the PBAT matrix. These improvements were attributed to the strong reinforcing effect of miscanthus fibers. The polarity difference between the PBAT matrix and the miscanthus fibers leads to weak interaction between the phases in the resulting composites. This weak interaction was evidenced in the impact strength and tensile strength of the uncompatibilized PBAT composites. Therefore, maleic anhydride (MAH)‐grafted PBAT was prepared as compatibilizer by melt free radical grafting reaction. The MAH grafting on the PBAT was confirmed by Fourier transform infrared spectroscopy. The interfacial bonding between the miscanthus fibers and PBAT was improved with the addition of 5 wt % of MAH‐grafted PBAT (MAH‐g‐PBAT) compatibilizer. The improved interaction between the PBAT and the miscanthus fiber was corroborated with mechanical and morphological properties. The compatibilized PBAT composite with 40 wt % miscanthus fibers exhibited an average heat deflection temperature of 81 °C, notched Izod impact strength of 184 J/m, tensile strength of 19.4 MPa, and flexural strength of 22 MPa. From the scanning electron microscopy analysis, better interaction between the components can be observed in the compatibilized composites, which contribute to enhanced mechanical properties. Overall, the addition of miscanthus fibers into a PBAT matrix showed a significant benefit in terms of economic competitiveness and functional performances. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45448.

Experimental Study on Heat Transfer and Thermo-Physical Properties of Covalently Functionalized Carbon Nanotubes Nanofluids in an Annular Heat Exchanger: A Green and Novel Synthesis

In order to eliminate the use of toxic acids in common carbon nanomaterial functionalization methods, a facile and eco-friendly procedure is introduced in this study to synthesize highly dispersed, covalently functionalized multiwalled carbon nanotubes (MWCNTs) for use in heat transfer fluids. The MWCNTs are treated covalently with clove buds in one pot using a free radical grafting reaction. The clove-treated MWCNTs (C-MWCNTs) are then dispersed in distilled water (DI water) at three different concentrations of C-MWCNTs (0.075, 0.125, and 0.175 wt %), resulting in C-MWCNT-DI water nanofluids. The effectiveness of the functionalization process is then verified using Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and transmission electron microscopy (TEM). UV–vis spectroscopy is also used to examine the stability of the C-MWCNTs in the base fluid. The thermal conductivity, density, and dynamic viscosity of the C-MWCNT-DI water nanofluids are studied experimentally, and th...

A bio-based, facile approach for the preparation of covalently functionalized carbon nanotubes aqueous suspensions and their potential as heat transfer fluids

In this study, we propose an innovative, bio-based, environmentally friendly approach for the covalent functionalization of multi-walled carbon nanotubes using clove buds. This approach is innovative because we do not use toxic and hazardous acids which are typically used in common carbon nanomaterial functionalization procedures. The MWCNTs are functionalized in one pot using a free radical grafting reaction. The clove-functionalized MWCNTs (CMWCNTs) are then dispersed in distilled water (DI water), producing a highly stable CMWCNT aqueous suspension. The CMWCNTs are characterized using Raman spectroscopy, X-ray photoelectron spectroscopy and transmission electron microscopy. The electrostatic interactions between the CMWCNT colloidal particles in DI water are verified via zeta potential measurements. UV–vis spectroscopy is also used to examine the stability of the CMWCNTs in the base fluid. The thermo-physical properties of the CMWCNT nano-fluids are examined experimentally and indeed, this nano-fluid shows remarkably improved thermo-physical properties, indicating its superb potential for various thermal applications.

Novel carbon nanotube composites by grafting reaction with water-compatible redox initiator system

Multi-walled carbon nanotubes were chemically functionalized with methacrylic acid and methacrylated bovine serum albumin by free radical grafting reaction to obtain novel nanocomposites. The nanotubes were synthesized by aerosol-assisted chemical vapor deposition, and then the monomers were directly grafted by the action of hydrogen peroxide/ascorbic acid redox pair which allows operating in water-compatible and eco-friendly environment without the generation of any toxic reaction by-product. A multi-technique approach was used to evaluate the effectiveness of the grafting process employing Fourier transform infrared, Raman, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, and thermogravimetric analyses. Considering the high importance of methacrylate polymers and bovine serum albumin, the proposed nanocomposites could be of great applicability in biomedical and pharmaceutical fields.

Dextran-Catechin Conjugate: A Potential Treatment Against the Pancreatic Ductal Adenocarcinoma

A polysaccharide-flavonoid conjugate was developend and proposed for the treatment of pancreatic ductal adenocarcinoma (PDAC). The conjugate was synthesized by free radical grafting reaction between catechin and dextran. The chemical characterization of the conjugate was obtained by UV-Vis, 1H-NMR, FT-IR and GPC analyses, while the functionalization degree was determined by the Folin-Ciocalteu assay. The biological activity of the catechin-dextran conjugate was tested on two different cell lines derived from human pancreatic cancer (MIA PaCa-2 and PL45 cells), and the toxicity towards human pancreatic nestin-expressing cells evaluated. Both the cancer cell lines are killed when exposed to the conjugate, and undergo apoptosis after the incubation with catechin-dextran which resulted more effective in killing pancreatic tumor cells compared to the catechin alone. Moreover, our experimental data indicate that the conjugate was less cytotoxic to human pancreatic nestin-expressing cells which are considered a good model of non-neoplastic pancreatic cells. The suitability of newly synthesized Dextran-Catechin conjugate in the treatment of PDAC was proved confirming the high potential application of the proposed macromolecula system in the cancer therapy.

Poly(2-hydroxyethyl methacrylate)-quercetin Conjugate as Biomaterial in Ophthalmology: An "ab initio" Study.

A novel polymeric material with antioxidant properties and suitable for ophthalmic application was synthesized by free radical grafting reaction between 2-hydroxyethyl methacrylate and quercetin. The presence of quercetin in the polymeric chain was confirmed by FT-IR and UV-Vis analyses, while an estimation of the amount of quercetin bound per gram of polymer was obtained by the Folin-Ciocalteu assay. The conjugate shows high biocompatibility (HET-CAM assay) and antioxidant and anti-inflammatory properties which were extensively investigated by specific in vitro tests.