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Alginate-based bio-nanocomposite reinforced with poly(2-hydroxypropyl methacrylamide) and magnetite graphene oxide for delivery of etoposide and photothermal therapy
(Elsevier Sci Ltd, 2024) Isiklan, Nuran; Geyik, Gulcan; Guncum, Enes
Recently, bio-nanocomposite nanogels/hydrogels composed of natural polymers and carbon-based nano- materials are attracting increasing attention in the fields of nanomedicine and bioengineering due to their unique properties. In this study, we propose the creation of an innovative multifunctional bio-nanocomposite based on alginate graft copolymer with poly(2-hydroxypropyl methacrylamide) (SA-g-PHPM) and magnetite graphene oxide (mGO) loaded with etoposide (EPS) for drug delivery and photothermal therapy (PTT). The SA-g-PHPM/ mGO bio-nanocomposite was synthesized using an emulsion method and exhibited favorable physicochemical properties. The structural functionalities and surface morphology of the SA-g-PHPM/mGO bio-nanocomposite were comprehensively characterized using spectroscopic techniques, including FT-IR, XRD, UV, DLS, TEM/FESEM, and AFM analyses. Under near-infrared (NIR) irradiation (808 nm, 1 Wcm-(2), 10 min), the SA-g-PHPM/ mGO bio-nanocomposite demonstrated the ability to effectively induce a temperature increase exceeding 29 degrees C. Additionally, exposure to NIR light and magnetic field led to an increased release of EPS whereas an increment in percentage of mGO caused a decreased EPS release. Notably, the synergistic effects of chemotherapy, light-triggered drug release, and PTT collectively contributed to a significant enhancement in lung cancer (H1299) cell death. In conclusion, our findings suggest that the developed SA-g-PHPM/mGO/EPS bionanocomposite serves as an efficient vehicle for multimodal therapy in lung cancer.
Aptamer-functionalized magnetic graphene oxide nanocarrier for targeted drug delivery of paclitaxel
(Elsevier Science Sa, 2018) Hussien, Nizamudin Awel; Isiklan, Nuran; Turk, Mustafa
Targeted drug delivery has come out as a golden system owing to its capability to reduce side effects and increase efficacy. The application of graphene oxide (GO) based nanomaterials for targeted delivery has recently attracted several researchers because of their advantageous properties. Herein, we have attempted to prepare aptamer-conjugated magnetic graphene oxide (MGO) nanocarrier, which can specifically target tumor cells. MGO nanocarriers were prepared by attaching Fe3O4 on the layer of GO and then, aptamer (APT) was linked as a targeting moiety. Paclitaxel (PAC), an anti-cancer drug, was also loaded on the nanocarrier. PAC loading and in vitro release results revealed a very good loading performance with entrapment efficiency 95.75% and high pH-responsive release. Cellular toxicity assay showed MGO nanocarriers are biocompatible having cell viability greater than 80% for L-929 fibroblast cell line. Besides, high cytotoxic effect was observed for PAC and PAC loaded MGO (MGO@PAC) on MCF-7 cancer cells, at different drug doses. Furthermore, flow cytometry investigation reveals that the obtained nanocarrier can specifically bind to MCF-7 cancer cells. Therefore, based on the results the prepared superparamagnetic nanocarrier could be considered as a promising agent for cancer drug delivery systems. (C) 2018 Elsevier B.V. All rights reserved.
Chemical modification of x-carrageenan with poly (2-hydroxypropylmethacrylamide) through microwave induced graft copolymerization: Characterization and swelling features
(Elsevier, 2023) Geyik, Guelcan; Isiklan, Nuran
In the last decade, interest in the development of new graft copolymers based on natural polysaccharides has grown remarkably due to their potential applications in the wastewater treatment, biomedical, nanomedicine, and pharmaceutical fields. Herein, a novel graft copolymer of x-carrageenan with poly(2-hydroxypropylmethacrylamide) (x-Crg-g-PHPMA) was synthesized using a 'microwave induced' technique. The synthesized novel graft copolymer has been well characterized in terms of FTIR, 13C NMR, molecular weight determination, TG, DSC, XRD, SEM, and elemental analyses, taking x-carrageenan as a reference. The graft copolymers' swelling characteristics were investigated at pH 1.2 and 7.4. The results of swelling studies displayed that the incorporation of PHPMA groups on x-Crg provides increasing hydrophilicity. The effect of PHPMA percentage in the graft copolymers and pH of the medium on the swelling percentage was studied and the findings exhibited that swelling ability increased with the increment in PHPMA percentage and pH of the me-dium. The best swelling percentage was attained at pH = 7.4 and a grafting percentage of 81 % reaching 1007 % at the end of 240 min. Moreover, cytotoxicity of the synthesized x-Crg-g-PHPMA copolymer was assessed on the L929 fibroblast cell line and obtained to be non-toxic.
Controlled release of indomethacin from crosslinked alginate beads
(Walter De Gruyter Gmbh, 2008) Inal, Murat; Yigitoglu, Mustafa; Isiklan, Nuran
Beads of the sodium alginate ( NaAlg) were prepared by dropping aqueous sodium alginate ( NaAlg) into glutaraldehyde ( GA) as a crosslinker and HCl as a catalyst mixture solution. Beads prepared were used to deliver a model non-steroid, anti-inflammatory drug, indomethacin ( IM). The beads were characterized with Fourier transform infrared spectroscopy ( FTIR), differential scanning calorimetry ( DSC) and scanning electron microscopy ( SEM). Chemical stability of the IM after encapsulation into beads was confirmed by FTIR. SEM photograph indicated that alginate bead has spherical shape and rough surface. Preparation conditions of the beads were optimized by considering the percentage of entrapment efficiency, swelling capacity of the beads, particle size and their release data. In vitro release studies were performed in simulated gastric fluid ( pH 1.2) for the initial 2 h, followed by simulated intestinal fluid ( pH 7.4) for 4 h. Effects of variables such as, GA concentration, exposure time to GA, drug/ polymer ( d/ p) ratio and percentage of HCl on the release of the IM were investigated. It was observed that, IM release from the beads decreased with increasing GA concentration, exposure time to GA, d/ p ratio and percentage of HCl. The highest cumulative IM release obtained at the end of 6 h was 68% for alginate beads which were prepared with 0.5% HCl. On the other hand the least cumulative IM release obtained was to be 20 % for alginate beads which were prepared with 30 min exposure time to GA. In order to understand the crosslinking of the polymeric matrix, the molar mass between crosslinks were calculated using the swelling parameters. It was also found from the swelling experiments that swelling degree of the beads increases with increase in the temperature. The release data have been fitted to an empirical equation to estimate the kinetic parameters. The diffusion coefficient was also calculated for the transport of the drug through the polymeric beads. Values of these parameters were found to be consistent with the release data.
Design and development of pH-responsive alginate-based nanogel carriers for etoposide delivery
(Elsevier, 2023) Geyik, Gulcan; Guncum, Enes; Isiklan, Nuran
Recently, pH-responsive nanogels are playing progressively important roles in cancer treatment. The present study focuses on designing and developing pH-responsive alginate-based nanogels to achieve a controlled release of etoposide (Et) while enhancing its hydrophilicity. Alginate (ALG) is grafted with 2-hydroxypropyl methacrylamide (HPMA) through a microwave-supported method, and the chemical structure of the graft copolymer (ALG-g-PHPMA) was verified by 1H/13C NMR and FTIR techniques. The ALG-g-PHPMA and anticancer drug loaded ALG-g-PHPMA@Et nanogels were obtained using an emulsion method, and their structures were characterized through FTIR, TG/DSC, AFM/TEM, BET, and DLS analyses. The ALG-g-PHPMA nanogels demonstrated a good drug encapsulation efficiency (79.60 %), displaying a pH-dependent release profile and an in vitro accelerated release of Et compared to the ALG nanogels. Thermal and BET analyses revealed enhanced stability, surface area, and porosity volume of the alginate nanogels. The grafting of PHPMA chains onto alginate altered the surface topology of the ALG nanogels, resulting in lower surface roughness. Furthermore, cytotoxicity tests showed the high biocompatibility of the ALG-g-PHPMA copolymer and its nanogels. The ALG-g-PHPMA@Et nanogels exhibited a higher anticancer effect on lung cancer (H1299) cells than free etoposide. These results suggest that the ALG-g-PHPMA nanogels can be applied as a pH-dependent nanoplatform for delivering anticancer drugs.
Design and fabrication of hybrid triple-responsive x-carrageenan-based nanospheres for controlled drug delivery
(Elsevier, 2021) Geyik, Gulcan; Isiklan, Nuran
In the last two decades, the utilization of magnetic nanospheres in intelligent polymeric structures have received increased attention of researchers in numerous biomedical applications. Here, hybrid nanostructured triple-responsive magnetic nanospheres (kappa-Car-g-P(AA/DMA)@Fe3O4) containing inorganic iron oxide core (Fe3O4) and organic graft copolymeric shell based on x-carrageenan (kappa-Car) and poly(acrylic acid/dimethylaminoethyl methacrylate) (P(AA/DMA)) were synthesized by microwave induced co-precipitation technique. The structure, size, surface morphology, magnetic property and stability of synthesized kappa-Car-g-P(AA/DMA)@Fe3O4 magnetic nanospheres were characterized using FTIR, UV, XRD, TEM, Zeta-sizer, and VSM. kappa-Car-g-P(AA/DMA)@Fe3O4 nanospheres were loaded with 5-Fluorouracil (5-FU) as an antineoplastic drug, and their 5-FU release behavior was explored in diverse graft yields, pH values, temperatures and in the existence of an alternating magnetic field. The kappa-Car-g-P(AA/DMA)@Fe3O4 nanospheres demonstrated pH-, thermo-, and magnetic field-responsive 5-FU release with good biocompatibility and excellent anticancer activity. In addition, 5-FU release under 50 mT magnetic field reached to 100% within 4 h. This work exhibits that hybrid nanospheres have a triple stimuli-responsive influence, which is of principal importance for the future design and application of multi-functional responsive platforms to develop externally stimulated release of active agents and their healthcare capability.
Development and characterization of dual sensitive poly(N,N-diethyl acrylamide) grafted alginate microparticles
(Elsevier Science Bv, 2019) Isiklan, Nuran; Altinisik, Zeynep
Temperature and pH dual sensitive materials have attracted much interest in the fields of tissue engineering and drug delivery. In this study, a novel temperature and pH dual sensitive poly(N,N-diethyl acrylamide) grafted alginate (A-g-PDEA) microparticles were developed for 5-fluorouracil (5-FU) delivery. The structures of 5-FU loaded A-g-PDEA microparticles were characterized by FTIR, DSC, SEM, and XRD analyses. The effect of PDEA grafting percentage, temperature and pH on the swelling ratio and the release of 5-FU was explored. The obtained results displayed that the 5-FU release was controlled by both the temperature and pH of the medium. Furthermore, A-g-PDEA microparticles demonstrated a sustained release of 5-FU compared to free 5-FU. Moreover, the 5-FU release and swelling ratio of A-g-PDEA microparticles decreased with the increase in grafting percentage, crosslinking time and 5-FU/copolymer ratio. All the results indicated that A-g-PDEA microparticles are promising candidates for the sustained and controlled delivery of drugs.
Development and characterization of polymeric-based nanoparticles for sustained release of amoxicillin - an antimicrobial drug
(Taylor & Francis Ltd, 2018) Guncum, Enes; Isiklan, Nuran; Anlas, Ceren; Unal, Nilgun; Bulut, Elif; Bakirel, Tulay
In this study, amoxicillin (AMO)-loaded poly(vinyl alcohol)/sodium alginate (PVA/NaAlg) nanoparticles were prepared as a polymer-based controlled release system. The physicochemical properties of the obtained nanoparticles were investigated by XRD, DSC/TGA, particle size analyses and zeta potential measurements. The average particle sizes were in the range from 336.3 +/- 25.66 to 558.3 +/- 31.39 nm with negative zeta potential values from -41.86 +/- 0.55 to-47.3 +/- 2.76 mV. The influences of PVA/NaAlg ratio, span 80 concentration, exposure time to glutaraldehyde (GA) and the drug/polymer ratio on AMO release profiles were evaluated. In vitro drug release studies showed a controlled and pH dependent AMO release with an initial burst effect. XRD patterns and DSC thermograms of AMO-loaded nanoparticles revealed that the drug in the nanoparticles was in amorphous form, which was more stable than the crystalline form. The antibacterial activity of the optimal formulation was also investigated. The minimum inhibitory concentration (MIC) values of this formulation had the comparable antibacterial activity with that of pure AMO. These results indicate that the developed nanoparticles could be a promising candidate drug delivery system for AMO.
Development of chitosan-graphene oxide blend nanoparticles for controlled flurbiprofen delivery
(Elsevier, 2023) Erol, Umit Haydar; Guncum, Enes; Isiklan, Nuran
The use of natural polymeric nanoparticles (Nps) as drug carriers is a highly promising area of research in the field of drug delivery systems because of their high efficiency. In this study, flurbiprofen (FB) loaded chitosangraphene oxide (CS-GO) blend Nps were synthesized as a controlled delivery system using the emulsion method. The crystalline, molecular, and morphological structures of the prepared CS-GO Nps were characterized using a variety of analytical methods, including Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-Ray diffractometry (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). It was found that the introduction of GO into the CS nanoparticle formulation increased its thermal stability. The range of the average particle size was between 362 & PLUSMN; 5.06 and 718 & PLUSMN; 2.21 nm, with negative zeta potential values between -7.67 & PLUSMN; 4.16 and - 27.93 & PLUSMN; 2.26 mV. The effects of the CS/GO ratio, the FB/polymer ratio, the amount of span 80, and the cross-linker concentration were assessed on FB release profiles. In vitro release studies displayed a two-stage release behaviour with a fast initial release of the FB, followed by sustained and extended release, and the incorporation of GO into the CS Nps made the FB release more sustained and controlled manner. Besides, the cytotoxicity test of the FB-loaded CS-GO Nps was studied through MTT assay, and it was found that they were biocompatible. Based on these findings, it can be inferred that the prepared CS-GO Nps might be a promising candidate drug carrier system for FB.
Development of thermo-responsive poly(vinyl alcohol)-g-poly(N-isopropylacrylamide) copolymeric membranes for separation of isopropyl alcohol/water mixtures via pervaporation
(Elsevier Science Inc, 2016) Kursun, Fatma; Isiklan, Nuran
This study aims to develop thermo-responsive poly(N-isopropylacrylamide) (PNIPAAm) grafted poly(vinyl alcohol) (PVA-g-PNIPAAm) copolymer membranes for separation of isopropyl alcohol (IPA)/water mixtures via pervaporation. PVA-g-PNIPAAm copolymers were synthesized by microwave supported graft copolymerization. Structure of copolymers was characterized by element analysis, FTIR, TGA/DTG/DSC, C-13 NMR and SEC. PVA-g-PNIPAAm membranes prepared with casting technique were characterized by SEM-AFM. Effects of grafting yield, operation temperature, and feed concentration on separation factor and flux were investigated to determine the membrane performance. The maximum separation factor was 95 with flux of 0.011 kg/m(2) h at 87.4% IPA. Thermo-responsive PVA-g-PNIPAAm membranes developed in this study are promising for pervaporation. (C) 2016 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.
Development of thermo/pH-responsive chitosan coated pectin-graft-poly(N, N-diethyl acrylamide) microcarriers
(Elsevier Sci Ltd, 2019) Isiklan, Nuran; Tokmak, Seyma
Pectin based micro/nanocarriers display promising properties for biomedical applications. In this study, thermo/pH-responsive chitosan coated pectin-graft-poly(N,N-diethyl acrylamide) (Pec-g-PDEAAm/CS) microcarriers containing 5-Fluorouracil (5-FU) as a model drug were developed. The structure, thermal stability and surface morphology of 5-FU-loaded microcarriers were investigated using FTIR, XRD, DSC and SEM. Microcarrier formulations were fabricated by varying grafting yield, drug/copolymer ratio, chitosan, and crosslinking agent concentrations. The effect of these parameters on swelling degree and 5-FU release was explored. It was observed that the grafting of pectin with poly(N,N-diethyl acrylamide) ensured sustained/controlled and thermo/pH responsive release of 5-FU. Besides, in vitro cytotoxicity results displayed that Pec-g-PDEAAm/CS microcarriers had good biocompatibility. Results illustrated that 5-FU release and swelling degree of the microcarriers were greatly controlled by especially chitosan shell, 5-FU/copolymer ratio and crosslink density. Therefore, based on the findings the developed thermo/pH-responsive Pec-g-PDEAAm/CS microcarriers might be considered as a promising carrier for controlled drug delivery.
Graft copolymerization of itaconic acid onto sodium alginate using benzoyl peroxide
(Elsevier Sci Ltd, 2010) Isiklan, Nuran; Kursun, Fatma; Inal, Murat
Graft copolymers of sodium alginate (NaAlg) with itaconic acid (IA) were prepared in aqueous solution using benzoyl peroxide (BPO) as the initiator. Grafted copolymers (NaAlg-g-PIA) were characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy scanning electron, microscopy and thermogravimetric analysis. The grafting parameters, including the graft yield (GY%) of the graft copolymer and the grafting efficiency (GE%) of the reaction were evaluated comparatively. The effects of the reaction variables such as the reaction time, temperature, percentage of sodium alginate, monomer and initiator concentrations on these parameters were studied. It was observed that GY and GE first increased and then decreased with increasing polymerization temperature, concentrations of IA, and BPO. The optimum grafting conditions for maximum graft yield were obtained with reaction time of 1 h, reaction temperature of 85 degrees C. IA concentration of 1.38 M. BPO concentration of 1.82 x 10(-2) M and percentage of NaAlg 1.5 g/dL. (C) 2009 Elsevier Ltd. All rights reserved.
Graft Copolymerization of Itaconic Acid onto Sodium Alginate Using Ceric Ammonium Nitrate as Initiator
(John Wiley & Sons Inc, 2009) Isiklan, Nuran; Kursun, Fatma; Inal, Murat
Graft copolymers of sodium alginate (NaAlg) with itaconic acid (IA) were prepared in aqueous solution using ceric ammonium nitrate (CAN) as the redox initiator under N(2) atmosphere. The carboxylic acid groups of IA were neutralized with sodium hydroxide before grafting process. Grafted copolymers as sodium salts (NaAlg-g-PIA) were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, intrinsic viscosity measurement, differential scanning calorimetry, and thermogravimetric analysis. The graft yield (GY %) of the graft copolymer and the grafting efficiency (GE %) of the reaction were evaluated comparatively. The effects of the reaction variables such as the reaction time, temperature, percentage of NaAlg, monomer and initiator concentrations on these parameters were studied. It was observed that GY% and GE% increased and then decreased with increasing concentrations of IA and polymerization temperature. The optimum grafting conditions for maximum GY were obtained with a reaction time of 5 h, reaction temperature of 30 degrees C, IA concentration of 0.23 M, CAN concentration of 9.12 X 10(-2) M and percentage of NaAlg 0.5 g/dL. The overall activation energy for the grafting was also calculated to be 1135 cal/mol. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 114: 40-48, 2009
Hydroxypropyl cellulose functionalized magnetite graphene oxide nanobiocomposite for chemo/photothermal therapy
(Elsevier, 2023) Isiklan, Nuran; Hussien, Nizamudin Awel; Turk, Mustafa
In this work, graphene oxide nanosheets (GO) are dual functionalized with Fe3O4 nanoparticles and hydrox-ypropyl cellulose (CLS) for chemo/phototherapy. The TEM, XRD, FTIR, Raman, UV, TG, DLS, and VSM analyses were used to confirm the CLS and Fe3O4 incorporated GO (CLS@mGO) nanobiocomposite structure. Function-alization of magnetite graphene oxide surface by CLS not only improved biocompatibility, colloidal stability, and entrapment efficiency for paclitaxel (PTX) but also accelerated PTX release. Under 808 nm laser light, the CLS@mGO-PTX nanobiocomposite displayed good photothermal features. The CLS@mGO-PTX nano-biocomposite exhibited high photothermal conversion efficiency (47.85%) and photo stability. The notable synergistic chemo/photothermal impacts have also been determined by the in vitro experiments in killing MCF-7 cancer cells. The results of these experiments exhibited that compared to single phototherapy and chemotherapy, chemo/phototherapy could more effectively kill cancer cells by synergetic anticancer impact. Therefore, the CLS@mGO-PTX nanobiocomposite has great potential for chemo/phototherapy.
ICG-Conjugated magnetic graphene oxide for dual photothermal and photodynamic therapy
(Royal Soc Chemistry, 2016) Ocsoy, Ismail; Isiklan, Nuran; Cansiz, Sena; Ozdemir, Nalan; Tan, Weihong
Aptamer-functionalized magnetic graphene oxide conjugates loaded with indocyanine green (ICG) dye, or Apt@ICG@mGO, have been successfully developed for dual-targeted photothermal and photodynamic therapy. In general, a drug or its carrier or their dosage can be important issues in terms of toxicity. However, in this system, each component used is quite safe, biocompatible and clean. For instance, ICG, a Food and Drug Administration (FDA) approved near-infrared (NIR) dye, serves as both a photothermal and photodynamic agent. It is immobilized on the surface of mGO via a physical interaction called "pi-pi stacking". The mGO, as a most biocompatible member of the carbo family, is selected for use as a platform for aptamer and ICG dye conjugation, as well as a photothermal agent. The light in the near-infrared region (NIR) was chosen as a harmless light source for activating the agents for photothermal therapy (PTT) and photodynamic therapy (PDT). The magnetic properties of mGO are also used for separation of Apt@ICG@mGO conjugates from the reaction medium. Aptamer sgc8 acts as a targeting ligand to selectively and specifically bind to a protein on the membrane of cancer cell line CCRF-CEM. After the aptamer-functionalized ICG@mGO conjugates are incubated with target CEM cells at 37 degrees C for 2 hours, they are bound to cells or they may be internalized into the cell via endocytosis. More significantly, we demonstrated that the Apt@ICG@mGO conjugates produce heat for photothermal therapy (PTT) and singlet oxygen for photodynamic therapy (PDT) upon NIR laser irradiation at 808 nm. Thus, remarkably efficient cancer cell destructions with similar to 41% and similar to 60% and similar to 82% cell killing using 10, 50 and 100 ppm Apt@ICG@mGO, respectively are achieved in 5 min light exposure.
ICG-conjugated magnetic graphene xxide for dual photothermal and photodynamic therapy
(Lippincott Williams & Wilkins, 2015) Ocsoy, Ismail; Isiklan, Nuran; Cansiz, Sena; Ozdemir, Nalan; Tan, Weihong
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In vitro release study of diltiazem hydrochloride from poly(vinyl pyrrolidone)/sodium alginate blend microspheres
(Wiley, 2008) Sanli, Oya; Bicer, Emine; Isiklan, Nuran
Polymeric blend microspheres of poly(vinyl pyrrolidone) (PVP) with sodium alginate (NaAlg) were prepared by cross-linking with calcium ions and used to deliver a calcium channel blocker drug, diltiazem hydrochloride (DT). The prepared microspheres were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. Scanning electron microscopy confirmed the spherical nature of the particles. Preparation conditions for the microspheres were optimized by considering the percentage entrapment efficiency, particle size, and swelling capacity. Effects of variables such as PVP/NaAlg ratio, molecular weight of PVP, cross-linker concentration, and drug/polymer ratio on the release of DT were discussed at two different pH values (1.2, 6.8) at 37 degrees C. It was observed that DT release from the microspheres decreased with increasing molecular weight of PVP and extent of cross-linking. However, DT release increased with increasing PVP content and drug/polymer ratio (d/p) of the blend microspheres. The highest DT release percentage was obtained as 99% for PVP/NaAlg ratio of 1/2 with d/p ratio of 1/2 at the end of 4 h. It was also observed from release results that DT delivery from the microspheres through the external medium are much higher at low pH (1.2) value than that of high pH (6.8) value. The drug release from the microspheres mostly followed Fickian transport. (c) 2007 Wiley Periodicals, Inc.
Magnetic graphene oxide functionalized alginate-g-poly (2-hydroxypropylmethacrylamide) nanoplatform for near-infrared light/ pH/magnetic field-sensitive drug release and chemo/phototherapy
(Elsevier, 2024) Guncum, Enes; Geyik, Gulcan; Isiklan, Nuran
Multifunctional nanoplatforms developed from natural polymers and graphene oxide (GO) with enhanced biological/physicochemical features have recently attracted attention in the biomedical field. Herein, a new multifunctional near -infrared (NIR) light-, pH- and magnetic field -sensitive hybrid nanoplatform (mGO@AL-gPHPM@ICG/EP) is developed by combining iron oxide decorated graphene oxide nanosheets (mGO) and poly(2hydroxypropylmethacrylamide) grafted alginate (AL-g-PHPM) copolymer loaded with indocyanine green (ICG) and etoposide (EP) for chemo/phototherapy. The functional groups, specific crystal structure, size, morphology, and thermal stability of the nanoplatform were fully characterized by XRD, UV, FTIR, AFM/TEM/FE-SEM, VSM, DSC/TG, and BET analyses. In this platform, the mGO and ICG, as phototherapeutic agents, demonstrate excellent thermal effects and singlet oxygen production under NIR-light (808 nm) irradiation. The XRD and DSC analysis confirmed the amorphous state of the ICG/EP in the nanoparticles. In vitro photothermal tests proved that the mGO@AL-g-PHPM@ICG/EP nanoparticles had outstanding light stability and photothermal conversion ability. The in vitro release profiles presented NIR light-, pH- and magnetic field -controlled EP/ICG release behaviors. In vitro experiments demonstrated the excellent antitumor activity of the mGO@AL-g-PHPM@ICG/EP against H1299 tumor cells under NIR laser. Benefiting from its low-cost, facile preparation, and good dualmodal therapy, the mGO@AL-g-PHPM@ICG/EP nanoplatform holds great promise in multi -stimuli -sensitive drug delivery and chemo/phototherapy.
Microwave assisted synthesis and characterization of sodium alginate-graft-poly(N,N '-dimethylacrylamide)
(Elsevier Science Bv, 2016) Akin, Alper; Isiklan, Nuran
Modification of sodium alginate (NaAlg) was carried out using N,N'-dimethylacrylamide (DMAAm) as a monomer and azobisizobutyronitrile (AIBN) as an initiator under microwave irradiation. The effect of reaction conditions such as concentrations of DMAAm, AIBN, NaAlg as well as microwave power and temperature on grafting and grafting efficiency has been explored. Maximum grafting and grafting efficiency has been observed at 1 h of grafting time, 0.291 M of DMAAm concentration, 500W microwave irradiation power, 0.134M of AIBN concentration, 75 degrees C of reaction temperature and 0.5 g/dL of NaAlg concentration. The grafted copolymer has been characterized by FTIR, DSC, TGA, C-13 NMR, XRD, SEM, and GPC analysis. Cytotoxicity as standard MTT assay, apoptotic and necrotic effects of graft copolymer were investigated on L929 fibroblast cell. It has been found that the grafted copolymer is biocompatible and thermally more stable than the ungrafted alginate. (c) 2015 Elsevier B.V. All rights reserved.
Microwave based synthesis and spectral characterization of thermo-sensitive poly(N,N-diethylacrylamide) grafted pectin copolymer
(Elsevier Science Bv, 2018) Isiklan, Nuran; Tokmak, Seyma
The functionalization of polysaccharides with synthetic polymers has attracted great attention owing to its application in many industrial fields. The aim of this work was to study the impact of pectin functionalization with N, N-diethylacrylamide (DEAAm). Pectin was modified via microwave-induced graft copolymerization of DEAAm using ceric ammonium nitrate (CAN) and N,N,N',N'-tetramethylethylenediamine (TEMED). FTIR, C-13 NMR, DSC/TGA, XRD, and SEM techniques were used to verify the structure of graft copolymers. Various reaction conditions such as microwave irradiation time, temperature, microwave power, monomer, initiator, and TEMED concentrations were investigated to get a maximum grafting yield of 192%. Lower critical solution temperatures (LCST) of graft copolymers were determined by UV spectroscopy. Graft copolymers were found to be thermo-sensitive, with LCST of 31 degrees C and high thermal resistance. Biocompatibility test of copolymers showed that copolymers were not cytotoxic to L929 fibroblasts cells and can be used as a biomaterial. (C) 2018 Elsevier B.V. All rights reserved.

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