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Synthesis, Characterization, and Study of PLGA Copolymer in Vitro Degradation  [PDF]
Anamaria Teodora Coêlho Rios Silva, Barbara Camilla Oliveira Cardoso, Maria Elisa Scarpelli Ribeiro e Silva, Roberto Fernando Souza Freitas, Ricardo Geraldo Sousa
Journal of Biomaterials and Nanobiotechnology (JBNB) , 2015, DOI: 10.4236/jbnb.2015.61002
Abstract: The poly(lactic-co-glycolic acid), known as PLGA, is one of the main bioreabsorbable polymers used in the field of medicine today. This copolymer is widely applied in sutures, devices geared toward the controlled release of medication, and the guided regeneration of bone tissue as it presents a short degradation time. This work aimed to synthesize the 82/18 PLGA (expressed by the mass ratio of D,L-lactide and glycolide, respectively), to characterize and study the in Vitro degradation in the form of rods in phosphate buffer solution (PBS). The copolymer was synthesized by opening the cyclic dimer rings of the monomers D,L-lactide and glycolide, in the presence of the tin octanoate initiator and of the lauryl alcohol co-initiator. The characterization of the copolymer and the follow-up of its in vitro degradation were studied using: Differential Scanning Calorimetry (DSC), Thermogravimetry (TG), Infrared Molecular Absorption Spectroscopy with Fourier Transform (FTIR), Rheometry, and Scanning Electron Microscopy (SEM). Through these characterization techniques, it was possible to obtain the glass transition temperature, thermal stability, chemical composition, morphology, and molar mass of both the synthesized and the degraded copolymer. The molar mass of the synthesized copolymer was, approximately, 106 g·mol-1. The degradation rate of PLGA significantly increased from the 19th to the 28th day in PBS. After 28 days in PBS, the glass transition temperature and the molar mass reduced from 45°C to 17°C and from 1.5 × 106 g·mol-1 to 7.5 × 10g·mol
Apoptosis of HepG2 cells in vitro induced by emodin-loaded nanoparticles using a newly synthesized PLGA-STPGS as carrier

- , 2018, DOI: 10.7652/jdyxb201805028
Abstract: 摘要:目的 合成高分子材料乙交酯丙交酯共聚物-琥珀酰基维生素E聚乙二醇1000琥珀酸酯(PLGA-STPGS),并以其为载体制备大黄素PLGA-STPGS纳米粒(EPTN),考察其体外诱导人肝癌细胞HepG2的凋亡效果。方法 用市售材料PLGA和TPGS为原料,采用酯化反应合成高分子材料PLGA-STPGS,并用红外光谱、氢核磁共振、凝胶渗透层析、差示扫描量热法分别对其进行表征;以PLGA-STPGS为载体,采用乳化溶剂挥发法制备EPTN和大黄素??PLGA??纳米粒(EPN)并测定二者的粒径、载药量和包封率;分别使用流式细胞仪检测Annexin V-FITC/PI试剂盒和荧光显微镜观察TUNEL试剂盒处理的HepG2细胞在体外与EPTN和EPN孵育24、72h后的凋亡效果。结果 成功合成高分子材料PLGA-STPGS,数均分子量和分散度分别为25347和1.42;24、72h时EPTN和EPN诱导HepG2细胞的凋亡率分别为47.2%、62.4%和41.6%、52.1%;荧光显微镜观察到EPTN组比EPN组有更多呈绿色荧光的细胞核。结论 成功合成高分子材料PLGA-STPGS,以其为载体制备的EPTN能明显诱导HepG2细胞凋亡,而材料本身对细胞无明显毒性。
ABSTRACT: Objective To prepare emodin (EMO)-loaded PLGA-STPGS nanoparticles (EPTN) and evaluate the cellular apoptosis of EPTN in the human liver cancer cell line HepG2 in vitro after synthesis and characterization of a new copolymer of polylactide-co-glycolide-succinyl-D-α-tocopheryl polyethylene glycol 1000 succinate (PLGA-STPGS). Methods PLGA-STPGS was synthesized by esterfication method using PLGA and TPGS purchased from the market, and characterized using the fourier transform infrared spectrophotometer (FTIR), 1H nuclear magnetic resonance 1H-NMR), gel permeation chromatography (GPC), and differential scanning calorimetry (DSC) analysis. EPTN and EMO-loaded PLGA nanoparticles (EPN) were prepared by an emulsification solvent evaporation method; their particle size, drug loading, and entrapment efficiency were determined. Annexin V-FITC/PI Apoptosis Kit with a fluorescence-activated cell sorter quantitatively and TUNEL Apoptosis Kit under a fluorescence inversion microscope (FIM) qualitatively were used to detect the in vitro apoptotic effect on HepG2 cells induced by EPTN and EPN after incubation for 24 and 72 hours. Results PLGA-STPGS was successfully synthesized as a new material and further confirmed by the FTIR, 1H-NMR, DSC, and GPC analysis. The number average molecular weight (Mn) and polydispersity of the PLGA-STPG random copolymer was 25347 and 1.42. The apoptosis ratios of HepG2 cells incubated with EPTN and EPN for 24 and 72 hours were 54.2%, 62.4% and 41.6%, 52.1%, respectively. Compared with the EMO solution (EMS) group, most of the cellular nuclei in the NP groups were fluorescently labelled in green with TUNEL, and the EPTN group showed the highest level of nuclear green fluorescence observed using FIM. Conclusion PLGA-STPGS was successfully synthesized, and EPTN prepared with PLGA-STPGS as carrier exhibited a stronger effect on the apoptosis of HepG2 cells. The results also indicated that PLGA-STPGS had no obvious toxicity to HepG2 cells
Preparation, Characterization, In Vitro Release and Degradation of Cathelicidin-BF-30-PLGA Microspheres  [PDF]
Lili Li, Qifeng Wang, Hongli Li, Mingwei Yuan, Minglong Yuan
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0100809
Abstract: Cathelicidin-BF-30 (BF-30), a water-soluble peptide isolated from the snake venom of Bungarus fasciatus containing 30 amino acid residues, was incorporated in poly(D,L-lactide-co-glycolide) (PLGA) 75:25 microspheres (MS) prepared by a water in oil in water W/O/W emulsification solvent extraction method. The aim of this work was to investigate the stability of BF-30 after encapsulation. D-trehalose was used as an excipient to stabilize the peptide. The MS obtained were mostly under 2 μm in size and the encapsulation efficiency was 88.50±1.29%. The secondary structure of the peptide released in vitro was determined to be nearly the same as the native peptide using Circular Dichroism (CD). The ability of BF-30 to inhibit the growth of Escherichia coli was also maintained. The cellular relative growth and hemolysis rates were 92.16±3.55% and 3.52±0.45% respectively.
Síntese e caracteriza??o térmica e química do copolímero poli(D,L-lactídeo-co-glicolídeo)
Erbetta, Cynthia D. C.;Viegas, Carla C. B.;Freitas, Roberto F. S.;Sousa, Ricardo G.;
Polímeros , 2011, DOI: 10.1590/S0104-14282011005000063
Abstract: poly (d, l-lactide-co-glycolide) copolymer (plga) has attracted a great deal of interest due to their special characteristics as biomaterials since it is bioreabsorbable, biocompatible, nontoxic and the kinetics of degradation can be modified by the ratio of monomers in copolymerization. in this work, the copolymers were synthesized at 175 oc, by opening the ring of cyclic dimers of d,l-lactide and glycolide monomers in the presence of tin(ii) octanoate initiator and lauryl alcohol co-initiator. the efficient control of the vacuum in the medium combined with adequate stirring were essential to the success of the synthesis. characterization of the copolymers samples was carried out by using differential scanning calorimetry (dsc), thermogravimetry (tg) and fourier transform infrared spectroscopy (ftir). we analyzed not only the products of reaction but also the initial monomers. the new synthesis route employed was appropriate and the poly(d, l-lactide-co-glycolide) was successfully obtained.
Effect of degradation of PLGA and PLGA/β-TCP scaffolds on the growth of osteoblasts
YanFang Yang,GongWen Tang,YunHui Zhao,Yang Zhang,XiuLan Li,XiaoYan Yuan
Chinese Science Bulletin , 2011, DOI: 10.1007/s11434-010-4132-1
Abstract: Osteoblasts were cultured on porous scaffolds of poly(L-lactide-co-glycolide) (PLGA) and PLGA/β-tricalcium phosphate (β-TCP) to evaluate their cytocompatibility. The proliferation of the cells on both scaffolds was examined before and after in vitro degradation for 4, 8 and 12 weeks under static (shaking water bath) and dynamic (cyclic loading) conditions. Results indicate that porous PLGA and PLGA/β-TCP scaffolds have good biocompatibility and can be used as effective templates for guiding the growth of osteoblasts. The degradation of the scaffolds affects the proliferation of osteoblasts and the cell viability decreased with the degradation time.
Synthesis and Analysis of Resorcinol-Acetone Copolymer  [PDF]
Ataru Kobayashi,Gen-ichi Konishi
Molecules , 2009, DOI: 10.3390/molecules14010364
Abstract: Synthesis and characterization of resorcinol-acetone copolymer is described. The polymer was prepared by trifluoroacetic acid-catalyzed polymerization of resorcinol with acetone. According to the 1H-NMR, 13C-NMR, and MALDI-TOF Mass spectra data, the obtained polymer had three types of repeating units: isopropylidene bridged-resorcinol, chromane ring, and spiro-shaped double chromane ring, indicating that polymerization proceeded via simultaneous addition-condensation and cyclization of resorcinol with acetone. The obtained polymer can be useful not only for the development of plastic materials such as thermosets, adhesives, and coatings but also for the synthesis of biomaterials such as antimicrobial agents, pesticides, and medicines.
Synthesis, Characterization and In Vitro Anticancer Evaluation of Itaconic Acid Based Random Copolyester  [PDF]
J. Gowsika,R. Nanthini
Journal of Chemistry , 2014, DOI: 10.1155/2014/173814
Abstract: The present study deals with the synthesis and characterization of an aliphatic copolyester, poly [butylene fumarate-co-butylene itaconate] (PIFB) copolymer was obtained from itaconic acid, fumaric acid, and 1,4-butanediol using titanium tetraisopropoxide (TTiPO) through a two step process of transesterification and melt polycondensation. The synthesized aliphatic random copolyester was characterized with the help of FT-IR, 1H-NMR, 13C-NMR, viscosity measurements, Gel Permeation Chromatography (GPC) and X-ray diffraction (XRD) analysis. Thermal properties have been analyzed using thermogravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC). Hydrolytic degradation studies were carried out in acid and alkaline regions of various pH values. The synthesized copolymer was subjected to in vitro anticancer activity studies against human breast cancer (MCF-7) cell line. 1. Introduction The polymer synthesis was found to be an effective development on human chemotherapy. Polyesters, polyanhydrides, and so forth are mainly used in pharmaceutical, biomedical, soft tissue engineering, and drug delivery. Drug device polyester is used for plasma expanders and also tablet coating. Whenever a new drug molecule is synthesized, it is given orally or injected into the affected tissues. Nevertheless, this system of intake has disadvantage like an undesirable effect, poor drug efficiency, duration, concentration, bioavailability, and the drug that might not be controlled. To overcome this drawback, a new controlled release technology was developed. In this technology, a drug remains inside the human body for a prolonged period of time by releasing in a controlled manner [1]. The first drug delivery application is reported using hydrogel in 1960 [2]. In the beginning, biodegradable poly (glycolic acid) and poly (lactic acid) were used for tissue engineering system [3–5]. Later, poly (lactide-co-glycolide) was synthesized for medical application like dental implant and scaffold for bone TE [6]. In recent years, biodegradable polyesters are widely used for drug delivery, especially for anticancer drugs [7, 8]. Biodegradable polyesters have also attracted much attention as green materials and biomaterials in biodegradable fibers, nonwovens, films, sheets, bottles, injection-molded products, pharmaceutical, medical, biomedical engineering applications including drug delivery systems, and functional materials in tissue engineering [9–11]. Polyesters have good biocompatibility and biodegradation property which are concluded by many researchers in the past decades.
Role of hydroxypropyl-β-cyclodextrin on freeze-dried and gamma-irradiated PLGA and PLGA–PEG diblock copolymer nanospheres for ophthalmic flurbiprofen delivery
Vega E, Egea MA, Calpena AC, Espina M, García ML
International Journal of Nanomedicine , 2012, DOI: http://dx.doi.org/10.2147/IJN.S28481
Abstract: le of hydroxypropyl-β-cyclodextrin on freeze-dried and gamma-irradiated PLGA and PLGA–PEG diblock copolymer nanospheres for ophthalmic flurbiprofen delivery Original Research (2824) Total Article Views Authors: Vega E, Egea MA, Calpena AC, Espina M, García ML Published Date March 2012 Volume 2012:7 Pages 1357 - 1371 DOI: http://dx.doi.org/10.2147/IJN.S28481 Received: 22 November 2011 Accepted: 23 December 2011 Published: 12 March 2012 Estefanía Vega1, M Antònia Egea1, Ana Cristina Calpena2, Marta Espina1, M Luisa García1 1Department of Physical Chemistry, 2Department of Biopharmacy and Pharmaceutical Technology, Institute of Nanoscience and Nanotechnology, Faculty of Pharmacy, University of Barcelona, Barcelona, Spain Abstract: Poly(D,L-lactide-co-glycolide) and poly(D,L-lactide-co-glycolide) with poly(ethylene glycol) nanospheres (NSs) incorporating flurbiprofen (FB) were freeze-dried with several cryoprotective agents and sterilized by γ-irradiation. Only when 5.0% (w/v) hydroxypropyl-β-cyclodextrin (HPβCD) was used, a complete resuspension by manual shaking and almost identical particle size of the NSs was obtained after freeze-drying. In vitro drug release and ex vivo corneal permeation of NSs with and without HPβCD were evaluated. The presence of HPβCD resulted in a reduction of burst effect, providing a more sustained release of the drug. A significant decrease in the FB transcorneal permeation of NSs containing HPβCD was obtained, related to the slower diffusion of FB observed in the in vitro results. The uptake mechanism of the NSs was examined by confocal microscopy, suggesting that NSs penetrate corneal epithelium through a transcellular pathway. Ocular tolerance was assessed in vitro and in vivo by the Eytex and Draize test, respectively. Long-term stability studies revealed that γ-irradiated NSs stored as freeze-dried powders maintained their initial characteristics. Stability studies of the resuspended NSs after 3 months of storage in the aqueous form showed that NSs were stable at 4°C, while formulations stored at 25°C and 40°C increased their initial particle size.
Synthesis and micellization behavior of stimuli-responsive polypeptide hybrid triblock copolymer
JingYi Rao,ZhiYuan Zhu,ShiYong Liu
Chinese Science Bulletin , 2009, DOI: 10.1007/s11434-009-0244-x
Abstract: Polypeptide hybrid triblock copolymer, poly(L-glutamic acid)-b-poly(propylene oxide)-b-poly (L-glutamic acid) (PLGA-b-PPO-b-PLGA), was synthesized by the ring-opening polymerization of benzyl-L-glutamic N-carboxyanhydride (BLG-NCA) using poly(propylene glycol) bis(2-aminopropyl ether) as initiator, followed by the subsequent deprotection step. The obtained double hydrophilic triblock copolymer exhibits “schizophrenic” micellization behavior in aqueous solution upon dually playing with solution pH and temperature. The multi-responsive micellization behavior of this polypeptide hybrid triblock copolymer has been thoroughly investigated by 1H NMR, laser light scattering (LLS), temperature-dependent optical transmittance, and circular dichroism spectroscopy (CD).
Degradation versus self-assembly of block copolymer micelles  [PDF]
Alexander Muratov,Vladimir A. Baulin
Physics , 2012, DOI: 10.1021/la204625p
Abstract: The stability of micelles self-assembled from block copolymers can be altered by the degradation of the blocks. Slow degradation shifts the equilibrium size distribution of block copolymer micelles and change their properties. Quasi-equilibrium scaling theory shows that the degradation of hydrophobic blocks in the core of micelles destabilize the micelles reducing their size, while the degradation of hydrophilic blocks forming coronas of micelles favors larger micelles and may, at certain conditions, induce the formation of micelles from individual chains.
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