Increasing PEG Content Research Articles

Impact of PEG Content on Doxorubicin Release from PLGA-co-PEG Nanoparticles.

Nanoparticles (NPs) have become attractive vehicles for drug delivery in cancer therapy due to their ability to accumulate in tumours and mitigate side effects. This study focuses on the production of doxorubicin (DOX)-loaded NPs comprising Poly (lactic-co-glycolic acid)-Polyethylene glycol with varying PEG proportions and the examination of their impact on drug release kinetics. DOX-loaded NPs, composed of PLGA-co-PEG with PEG contents of 0%, 5%, 10%, and 15%, were synthesized by the solvent evaporation technique, exhibited spherical morphology, and had sizes ranging from 420 nm to 690 nm. In vitro drug release studies revealed biphasic profiles, with higher PEG contents leading to faster and more extensive drug release. The Baker-Lonsdale model demonstrated the best fit to the drug release data, indicating that the release process is diffusion-controlled. The diffusion coefficients for DOX determined ranged from 6.3 × 10-18 to 7.55 × 10-17 cm2s-1 and exhibited an upward trend with increasing PEG content in the polymer. In vitro cytotoxicity tests with CHO cells showed that unloaded NPs are non-toxic, while DOX-loaded PLGA-PEG 15% NPs induced a greater decrease in cellular viability compared to their PLGA counterparts. A mathematical relationship between the diffusion coefficient and PEG percentage was derived, providing a practical tool for optimizing DOX release profiles.

Effect of PEG concentration on drug release from PLA-PEG copolymers: A molecular dynamics simulation study

Mercaptopurine (6-MP), a cancer medication limited by its hydrophobic properties, was studied using molecular dynamics simulations with biodegradable copolymers (PLA-PEG, PLA-PEG-PLA, PEG-PLA-PEG) as drug carriers. The influence of PEG concentration in copolymers on drug release was examined. Results revealed that blending PEG with PLA or copolymerizing them affected hydrogen bond numbers and mixing energy in the drug carrier, dependent on copolymer type and PEG concentration. Introducing PEG into PLA chains increased hydrogen bonds and energy, but copolymerizing PLA and PEG did not consistently enhance hydrogen bond energy (PLA-PEG-PLA > PEG-PLA-PEG > PLA-PEG). Mixing energy was consistently elevated by PEG-PLA copolymerization, ranked PEG-PLA-PEG > PLA-PEG > PLA-PEG-PLA. The fastest drug release was observed with the PLA&PEG-10.9 carrier, attributed to weak PLA-PEG chain connections facilitating water access to PEG. Increasing PEG content reduced chain mixing energy, slowed drug release via stronger chain hydrogen bonding. Notably, PEG-PLA-PEG-8.7 exhibited the highest drug release rate due to quicker water penetration. The copolymer type and chain length were found to impact water molecule access to PEG and drug release rate significantly.

Effect of Poly(ethylene glycol) Configuration on Microbubble Pharmacokinetics.

Microbubbles (MBs) hold substantial promise for medical imaging and therapy; nonetheless, knowledge gaps persist between composition, structure, and in vivo performance, especially with respect to pharmacokinetics. Of particular interest is the role of the poly(ethylene glycol) (PEG) layer, which is thought to shield the MB against opsonization and rapid clearance but is also known to cause an antibody response upon multiple injections. The goal of this study was, therefore, to elucidate the role of the PEG layer in circulation persistence of MBs in the naïve animal (prior to an adaptive immune response). Here, we directly observe the number and size of individual MBs obtained from blood samples, unifying size and concentration into the microbubble volume dose (MVD) parameter. This approach enables direct evaluation of the pharmacokinetics of intact MBs, comprising both the lipid shell and gaseous core, rather than separately assessing the lipid or gas components. We examined the in vivo circulation persistence of 3 μm diameter phospholipid-coated MBs with three different mPEG2000 content: 2 mol % (mushroom), 5 mol % (intermediate), and 10 mol % (brush). MB size and concentration in the blood were evaluated by a hemocytometer analysis over 30 min following intravenous injections of 20 and 40 μL/kg MVD in Sprague-Dawley rats. Interestingly, pharmacokinetic analysis demonstrated that increasing PEG concentration on the MB surface resulted in faster clearance. This was evidenced by a 1.6-fold reduction in half-life and area under the curve (AUC) (p < 0.05) in the central compartment. Conversely, the AUC in the peripheral compartment increased with PEG density, suggesting enhanced MB trapping by the mononuclear phagocyte system. This was supported by an in vitro assay, which showed a significant rise in complement C3a activation with a higher PEG content. In conclusion, a minimal PEG concentration on the MB shell (mushroom configuration) was found to prolong circulation and mitigate immunogenicity.

Effect of Plasticization/Annealing on Thermal, Dynamic Mechanical, and Rheological Properties of Poly(Lactic Acid).

This study investigates the use of low molecular weight poly(ethylene glycol) (PEG) as a plasticizer for poly(lactic acid) (PLA). PLA/PEG blend films were prepared using the solvent casting method with varying mixing ratios. The films were analyzed using differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and dynamic rheological analysis. The results indicate that the addition of PEG as a plasticizer affects the thermal and mechanical properties of the PLA/PEG blend films. The study found that the glass transition and cold crystallization temperatures decreased with increasing PEG content up to 20 wt%, while the crystallinity and crystallization rate increased. The blends with up to 20 wt% PEG were miscible, but phase separation occurred when the plasticizer content was increased to 30 wt%. Subsequently, amorphous samples of neat PLA and PLA plasticized with 10 wt% of PEG underwent annealing at various temperatures (Ta = 80-120 °C) for durations ta of 1 and 24 h. The samples were then analyzed using DSC and DMA. The addition of PEG to PLA altered the content of α' and α crystalline forms compared to neat PLA at a given (Ta; ta) and favored the formation of a mixture of α' and α crystals. The crystallinity achieved upon annealing increased with increasing Ta or ta and with the incorporation of PEG.

Physicochemical Effects of PEG Content in Alginate-based Double Network Hydrogels as Hybrid Scaffolds

This study aims to prepare a double-network hydrogel as hybrid networks bearing both natural and synthetic polymers to obtain scaffolds with increased swelling capacity and tunable mechanical and morphological properties. Physically cross-linked alginate hydrogel was reinforced with various ratios of Poly(ethylene glycol) (PEG) polymers which were chemically gellated via UV light exposure with a water soluble initiator. Physicochemical properties of the resulting hydrogels were systematically investigated via Fourier-transform infrared (FT-IR) spectroscopy for chemical composition and Scanning Electron Microscopy (SEM) for their morphological features like porosity. Furthermore, the effect of PEG amount in the final hydrogel (10, 20 and 40%) on swelling capacity was evaluated as well as the rheological properties. Prepared double-network hydrogels were demonstrated to be composed of both natural alginate polymer and synthetic PEG chains in FT-IR spectrum. Although 10%PEG containing hydrogel was not significantly different in terms of swelling capacity from the alginate hydrogel alone, increasing PEG amount seems to have improved the swelling ability. Comparative reological studies presented that introducing covalently cross-linked PEG network into alginate one increased crosspoint of storage and loss moduli almost 12 times more providing a stiffer scaffold. Increasing PEG content decreased the pore size on SEM images, indicating more crosslinking points in hydrogel structure.

The correlation properties of polyethylene glycol in dimethyl sulphoxide by viscosimetric study

ABSTRACT This paper presents the experimental analysis of viscosimetric properties of poly(ethylene glycol) (PEG) in dimethyl sulphoxide DMSO . By the viscosimetric study of solutions of PEG/DMSO, the dynamic viscosity was measured under the influence of increasing PEG concentration (1 g/l to 10 g/l) and increasing temperature (15°C to 45°C). The reduced dynamic viscosity and the activation energy of reduced dynamic viscosity E η are calculated. The polymer solutions exhibited a critical concentration c** , separating dilute solutions into extremely dilute solutions and dilute solutions. The most important results refer to the activation energy of reduced dynamic viscosity found from Arrhenius plots. The dependence of the activation energy on solution concentration and temperature is discussed. PEG behaviour can be extrapolated from the Flory-Huggins theory by decomposing such as E η = (E η ) ex di + (E η ) di + (E η ) cri . The extremely dilute solution behaviour of Arrhenius is described by the PEG-DMSO interaction and represented by the function (E η ) ex di . For the dilute solution behaviour of non-Arrhenius which is described by the interaction between the PEG-PEG and represented by the function (E η ) di . The critical solution behaviour of is described by the PEG-PEG and PEG-DMSO interactions and represented by the function (E η ) cri . Principles that aid one to understand and interpret such results are discussed.

Alleviating Impact of PEG Induced Drought Stress on Maize Seed Germination and Vigour with Effective Seed Priming Agents

Background: Drought stress poses a significant challenge to agricultural productivity, particularly in regions with limited water availability. Maize, a staple crop worldwide, is highly susceptible to drought stress, leading to reduced seed germination, stunted growth and ultimately diminished yields. Addressing this issue, in this study various phytohormones and polyamines were used as priming agents for seeds to evaluate its performance to mitigate drought stress in maize seed germination and vigour. It plays crucial roles in regulating plant growth and development, as well as responses to various environmental stresses, including drought. These hormones modulate physiological and biochemical processes, leading to adaptive changes that helps maize plants to cope with water scarcity. Methods: The experiment was conducted by exposing maize seeds primed with different phytohormones and polyamines in optimum along with non primed seeds (control) to various levels of PEG concentration ranging from -0.2 MPa to -1.0 MPa for creating drought stress. Primed seeds subjected to a germination test. The seedling growth parameters and seed vigour were evaluated to analyse better performing seed priming treatment to mitigate drought stress. Result: From the experiment it is concluded that increase in concentration of PEG (from -0.2 Mpa to -1.0 MPa) decreased the seed germination and seed vigour traits in maize. Among seed priming treatments, seeds primed with melatonin 150 µM showed greater performance seedling vigour and its related traits even under water deficit stress condition. In conclusion, seed priming with melatonin exhibited superior efficacy in mitigating drought stress in maize. This finding highlights the potential of melatonin as a promising seed priming agent for enhancing drought tolerance in maize seeds. As seed priming is simple, easy and cost effective method, farmers can use this technology as one of their practice to eliminate the effect of drought stress in maize crop.

Structure and thermal behaviour of different concentration PEG loaded PVA nanofibers

Poly vinyl alcohol (PVA) has established its credibility in the fields of filtration, biomedical and pharmaceutical areas. In this paper different concentration of poly (ethylene) glycol were added to PVA to prepare gel and its nano fibres. PEG is water soluble similar to PVA can give a uniform gel and a strong intermolecular bonding can be achieved by the addition of PEG in PVA. Fibres were prepared by having high wt.% of PEG loaded PVA nano fibres. Nano fibre mat having 0, 0.2,0.4 and 0.6 g PEG having low molecular weight was added in the 8.6 wt.% PVA solution and then fibres were prepared by using electro spinning technique. Nano fibres so prepared were characterised by SEM, XRD and DSC. SEM results reveal that increase of PEG concentration separated the nano fibres and increased the gap of the mesh size. SEM micro graphs depicts that produced nano fibres are homogenous in nature and there were no apparent gap between the PVA and PEG nano fibre. It may be explained that due to the high electric potential developed during the electro spinning process which helped the nano fibres to get stretched XRD patterns exhibited the crystal size increased on adding PEG in the PVA gel. Effect of PEG addition on Tm of PVA nano fibres has been determined by running their DSC scans. An additional peak of 158.13°C is observed for the sample having 0.4 g PEG. Melting temperature shifted from 215° C to 219°C due to increase in crystal size of PEG added PVA nano fibres.

Physiological response mechanism of European birch (Betula pendula Roth) to PEG-induced drought stress and hydration.

Drought stress is also one of the important abiotic factors limiting plant growth and development, and the global temperature is rising year by year, resulting in a dry environment in most terrestrial forests, which will continue to affect the growth, development and reproduction of tree species in forests. European birch(Betula pendula Roth.) native to Europe, introduced to the mountains of eastern Liaoning in 1981 (annual precipitation of about 800mm), European birch relative to downy birch (B. pubescens)has strong adaptability and drought tolerance and cold tolerance, can grow normally in eastern Liaoning, but it is easy to be affected by drought at the seedling stage and cause death, many arid and semi-arid areas have no introduction and practical application of European birch, and there is less research on the drought resistance of European birch. This study used different concentrations of PEG-6000 treatment to simulate drought stress and clarify the changes of various growth physiological parameters and photosynthetic characteristics of European birch seedlings under drought stress, in order to investigate the physiological response mechanism of European birch under drought stress . This study used different concentrations of PEG-6000 treatment to simulate drought stress and clarify the changes of various growth physiological parameters and photosynthetic characteristics of European birch seedlings under drought stress, in order to investigate the physiological response mechanism of European birch under drought stress. The findings demonstrated that stress duration and increasing PEG concentration had a highly significant impact on the growth traits of European birch seedlings (p<0.01); With increasing stress concentration and stress time, antioxidant enzyme activity, membrane lipid peroxidation, and osmoregulatory substance concentrations increased significantly (p<0.01); With increasing stress concentration and duration, photosynthetic parameters and pigments decreased highly significantly (p<0.01); Under different PEG concentration treatments, the anatomical structure of seedling leaves changed more noticeably; there was a significant effect (p <0.05) on the change in mean stomatal length and a highly significant effect (p<0.01) on the change in mean stomatal structure. The study's findings serve as a foundation for the selection and breeding of new drought-tolerant European birch species, as well as a theoretical underpinning for the use of this species in landscaping and the promotion of new drought-tolerant species in China.

High-Modulus Single-Ion-Conducting Electrolytes Based on a Rigid-Rod Polyanion

Single-ion-conducting electrolytes enable easy processing and can block Li dendritic growth, showing potential for use in solid-state batteries. We report solid electrolytes that combine a rigid-rod polyanion, poly(2,2′-disulfonyl-4,4′-benzidine terephthalamide) (PBDT), with Na+ or Li+ counterions, and poly(ethylene glycol) (PEG, Mn = 400 g mol–1). PBDT-PEG membranes show Young’s modulus from 90 to 2110 MPa that increases with the PBDT content and is >4× higher for Li-based vs Na-based electrolytes. We attribute this dramatically higher modulus in LiPBDT–PEG to poorer ion dissociation between Li+ and PBDT sulfonate groups and stronger interactions between LiPBDT and PEG. These membranes show an increase in ionic conductivity with increasing PEG concentration (0.1–7 μS cm–1 at 30 °C), reaching 0.13 mS cm–1 at 120 °C. These materials use highly rigid and charged PBDT double helices to “solidify” low-molecular-weight PEG into mechanically strong and highly single-ion-conductive solid polymer electrolytes with high thermal stability. Their combination of high cation conductivity and high modulus exceeds those of competing single-ion conductors at 30 °C.

Screening and Variability Studies in Rice Genotypes for Drought Tolerance and Yield

In the present investigation, laboratory and field screening of nine rice genotypes, namely, TM 12061, TM 12077, TM 12012, TM 14035, TM 16017, Senthuram, Vandhana, TKM 12 and Anna (R) 4 was taken up to assess their drought tolerance potential. For laboratory screening, the effect of different levels of PEG concentration namely, -0.2, -0.4, -0.6 and -1.0 MPa on germination, shoot length and root length were studied. There was a considerable decrease in the germination potential among all the genotypes with increase in PEG concentration. The culture, TM 12077 showed higher level of tolerance to PEG induced drought stress showing 30.8% germination with 3.2 cm and 8.85 cm shoot and root length, respectively at higher level of PEG concentration (1.0 MPa). In field screening under managed stress condition, the cultures, TM 12077 and TM 12012 showed higher accumulation of proline (4.15 mg/g). Chlorophyll stability index was more than 80% in the genotypes, TM 12012, TM 12077, and TM 12061. The culture TM 14035, the varieties Anna (R) 4 and Vandhana matured early in 115 days. Plant height was found to be moderate in Vandhana (103.3 cm), TM 12077(105.4 cm), TM 12061 (108.2 cm) and TM 12012 (110.5 cm) under managed stress condition. The number of tillers per plant, number of panicles/sqm and yield/hectare were maximum in the culture, TM 12077 under managed stress condition. Based on laboratory and field screening, the cultures TM 12077, TM 12012, and TM 12061 were found promising for water stress environment and can be utilized as donors in the breeding programs for drought tolerance in rice. High heritability coupled with moderate to high GA as per cent of mean was recorded for plant height, tillers per plant, chlorophyll Stability index and total chlorophyll content indicating the presence of additive gene effects and scope for their improvement through direct selection.

Graphene Oxide Nanoparticles Influence on the Electrical Properties of (PVA– PEG ) Blend

In this study, we preparation polymer blend (PVA-PEG) for three samples in different Molecular weight of PEG ( 4000-8000- 20000 g/mol) then preparation anther three samples polymer Nanocomposites (PVA-PEG-GO) by adding Graphene oxide nanoparticles (GO) concentrically (0.01wt) to blend polyvinyl Alcohol (PVA) and Polyethylene colacyl by using casting method after that study the Electrical properties (A-C) and structure (FTIR) and Optical Microscope enlargement (10x). The results of the study showed the effect of the addition of Graphene oxide on the alternating electrical properties have shown that the insulation constant. The electrophoresis and isolation loss of polymer compounds (PVA-PEG-) are reduced with increasing frequency of the electric field dominant and dielectric loss increases with increasing PEG concentration. The results showed that the alternating electrical conductivity of polymeric composite increased with increasing frequency and molecular weight of all prepared composite. It was also shown that the increase of electrical conductivity significantly with samples of poly nanoparticles (PEG-PVA-GO) by increasing the molecular weight of PEG and be at the highest molecular weight (20000g / mol).

Polyoxyethylene Diamine Modification of Poly(amide-imide)-polyethylene Glycol Exhibits Excellent Hydrophilicity, Degradability, and Biocompatibility

We designed and synthesized the polyoxyethylene diamine (H2N-PEG-NH2) and poly(amide-imide)-polyethylene glycol (PAI-PEG) copolymers. The physical and chemical properties, mechanical properties, and in vitro biocompatibility of the materials were characterized. The results showed that the best elongation at break and recovery were obtained when the amount of PEG was 5 wt%. With the increase in PEG content, the degradation rate, hydrophilic property, tensile strength and tensile modulus of the copolymer decreased to a certain extent. The material had the best thermal stability and mechanical properties when 5 wt% PEG was added. Cytocompatibility evaluation showed that the addition of PEG could enhance the cell compatibility of the material and make it potentially suitable for application in bone repair.

Preparation, Purification and Performance Evaluation of Polyclonal Antibody Against SARS-CoV-2 Produced in Rat.

Among all known human coronaviruses, some viruses (e.g., SARS-CoV-2) cause severe pneumonia or even death. With the regard to its spread and the importance of its rapid identification/treatment, and because pAbs are relatively cheap, able to bind to more sites on antigens and even neutralize them, this study was done for the production and purification of anti-SARS-CoV-2 polyclonal antibodies (pAb) in rats. Viral antigen purification was performed by PEG/NaCl precipitation. The efficiency of the sucrose cushion method was also investigated to produce a purer antigen. Immunization was done and antibody purification was performed by ammonium sulfate precipitation (33%), dialysis, and ion-exchange chromatography. Western blotting and enzyme-linked immunosorbent assay (ELISA) were performed to verify the antibody specificity. All data were analyzed by SPSS software. The results showed that the amount of concentrated virus increased with the increase of PEG concentration. Moreover, the sucrose cushion method increased its purity. Besides, induction of immune response in rats for pAb production with high titers was reached via these antigens and ELISA/western blot results indicated a suitable antibody-antigen interaction. Additionally, it was shown that ion-exchange chromatography could be a suitable technique for IgG purification. Herein, we presented a simple and cheap method for the purification of whole viral particles with relatively high quality. The results verified that these antigens could elicit a good immune response in the rat. The obtained pAbs showed a good specificity toward SARS-CoV-2 antigens. Accordingly, this study proposes a promising method for viral vaccine development.

Microgel dynamics within the 3D porous structure of transparent PEG hydrogels

We report an investigation on the effects of the confinement imposed by application-relevant poly(ethylene glycol) (PEG) hydrogel matrices with controlled porosity on the dynamics of soft microgels. Through a detailed characterization of the internal structure of the hydrogels at the nano and microscale, we were able to link the microgel dynamics, measured by particle tracking, to the 3D geometrical confinement imposed by the porous matrices. PEG hydrogels with a high degree of transparency and tunable pore sizes and volume fractions were obtained using freeze-thawing. We found that the porosity of the hydrogel networks is characterized by elongated channels having asymmetric sections, with the average size decreasing from about 7 to about 2 particle diameters, and the size distribution becoming narrower with increasing PEG content in the pre-reaction mixture. The microgel dynamics slowdown and change from diffusive to sub-diffusive as a result of the increasing confinement. The observed decrease in diffusivity is consistent with models of diffusion in cylindrical pores and can be attributed to hydrodynamic and steric effects in addition to geometrical constriction. A dependence of the effective diffusion coefficient on the pore volume fraction, which is unusually pronounced, suggests the presence of microgel-hydrogel interactions. Our results demonstrate that a detailed characterization of the 3D geometry of the porous network is of primary importance for the understanding of transport properties in complex, random porous media.

Nanoclay Reinforced Ternary Blends Based on Biodegradable Polymers for Drug Delivery Application.

In this study, ternary blends based on chitosan, polyvinyl alcohol, and polyethylene glycol reinforced with organically modified montmorillonite (nanoclay) clay were synthesized. These ternary blends were evaluated as transdermal drug delivery patches using tramadol as a model drug. The FTIR study showed interaction among important functional groups and compatibility among the mixing components. Among drug-loaded formulations, composite MA12 shows maximum thermal stability with 27.9% weight residue at 540°C. The prepared formulations exhibited crystalline nature as observed by XRD analysis. SEM studies revealed that there are no gaps and cracks in prepared films and nanoclay was found dispersed in the formulations. The swelling ratio was higher in pH 1.2 as compared to pH 4.5 and pH 6.8 buffers, and there was an increase in swelling with an increase in PVA concentration. Moreover, the drug release test performed in phosphate buffer pH 6.8 showed that tramadol release from nanocomposite films increases with an increase in PEG concentration. Permeation studies indicated that the rate of permeation increased with a decrease in PVA concentration. The permeation rate was found to be higher for samples without nanoclay. The overall results suggest nanocomposite films as excellent candidates for transdermal drug delivery application.

Enzymatic co-crosslinking of star-shaped poly(ethylene glycol) tyramine and hyaluronic acid tyramine conjugates provides elastic biocompatible and biodegradable hydrogels.

A combination of the viscoelastic properties of hyaluronic acid (HA) and the elastic properties of star shaped 8-arm poly(ethylene glycol) (8-arm PEG) was used to design in-situ forming hydrogels. Hydrogels were prepared by the enzymatic crosslinking of a partially tyramine modified 8-arm PEG and a tyramine conjugated HA using horseradish peroxidase in the presence of hydrogen peroxide. Hydrogels of the homopolymer conjugates and mixtures thereof were rapidly formed within seconds under physiological conditions at low polymer and enzyme concentrations. Elastic hydrogels with high gel content (≥95%) and high storage moduli (up to 22.4 kPa) were obtained. An in vitro study in the presence of hyaluronidase (100 U/mL) revealed that with increasing PEG content the degradation time of the hybrid hydrogels increased up to several weeks, whereas hydrogels composed of only hyaluronic acid degraded within 2 weeks. Human mesenchymal stem cells (hMSCs) incorporated in the hybrid hydrogels remained viable as shown by a PrestoBlue and a live-dead assay, confirming the biocompatibility of the constructs. The production of an extracellular matrix by re-differentiation of encapsulated human chondrocytes was followed over a period of 28 days. Gene expression indicated that these highly elastic hydrogels induced an enhanced production of collagen type II. At low PEG-TA/HA-TA ratios a higher expression of SOX 9 and ACAN was observed. These results indicate that by modulating the ratio of PEG/HA, injectable hydrogels can be prepared applicable as scaffolds for tissue regeneration applications.

Expression of CrMPK3 and alkaloid synthesis genes with antioxidants in callus of Catharanthus roseus in response to polyethylene glycol

To improve the yield of secondary metabolites and understand the effects of PEG-induced drought stress on physiological and biochemical characteristics and the relationship between CrMPK3 and some genes of vinblastine biosynthesis pathway, PEG (0, 2.5%, 5%, and 10%) was applied in different exposure times (24 and 72 h) on callus of two cultivars (Alba and Rosea) of Catharanthus roseus. The increase in malondialdehyde and proline contents by increasing PEG concentration in both exposure times in Alba cultivar were more than in Rosea cultivar. Also, the activity of antioxidant enzymes including catalase (CAT), guaiacol peroxidase (GOPX), superoxide dismutase (SOD), glutathione peroxidase (GPX), and ascorbate peroxidase (APX) in the Alba cultivar was higher than the Rosea cultivar. The relative expression of vinblastine biosynthesis genes including STR, DAT, and PRX1 was significantly increased in both cultivars, especially in the medium with 5% PEG. However, the change of T16H gene expression was more minor. Vinblastine content confirmed the expression results of these genes at different concentrations of PEG after 24 and 72 h in both cultivars. The relative expression of CrMPK3 and catalase genes increased significantly in all media containing PEG. The highest expression of CrMPK3 and catalase genes was obtained after 24 and 72 h at 5% PEG in both cultivars, respectively. Finally, PEG can induce the accumulation of vinblastine in calli of C. roseus through a signaling pathway in which MAPK trigger the activation of antioxidant enzymes with up-regulation of the TIAs biosynthesis genes.

Study of the PEG content effect on some properties of the PVA/PEG-EY films using the Raman, positron annihilation and impedance spectroscopies

PVA/PEG-EY blend structures are synthesized with PEG concentrations of 0, 1, 3, 5, 10, 15 and 20 wt% using casting method. The electrical and dielectric properties of the blend samples were studied with frequency in range (0.1 Hz to 20 MHz), via impedance spectroscopy. The Raman spectroscopy characterized and distinguish the structure of the prepared films. Theoretical results of Raman spectra of PVA, PEG and EY samples were analyzed based on linear response time-dependent density functional theory and then compared with experimental results of the samples. The microstructure and defect distribution of the synthesized samples were inferred using the positron annihilation spectroscopy (PAS). Experimental and theoretical Raman analysis indicates the increase of diffusion of EY and PEG. Broadband dielectric spectroscopy investigation on a broad range of frequencies shows that the enhancement of electrical conductivity of the prepared PVA/PEG-EY film with increasing PEG content. The considerable effect of the PEG content on the film microstructure was approved. The interactions between the PVA and PEG through the formation of hydrogen bonding modify the size and concentration of the free volume holes.

A highly transparent tri-polymer complex in situ hydrogel of HA, collagen and four-arm-PEG as potential vitreous substitute

There is a requirement of removal and replacement of vitreous for various ophthalmic diseases, e.g. retinopathy and retinal detachment. Clinical tamponades, e.g. silicone oil and fluorinated gases are used but limited due to their toxicity and some complications. A lot of polymer-based materials have been tested and proposed as vitreous substitute, but till date, there is no ideal vitreous substitute available. Thus, it requires to develop an improved vitreous substitute which will be highly suitable for vitreous replacement. We have developed tri-polymer complex in situ hydrogels by crosslinking among hyaluronic acid (HA), collagen (Coll) and four-arm-polyethylene glycol (PEG). All the developed hydrogels are biocompatible with NIH 3T3 mouse fibroblast cells, having pH in the range 7–7.44 and refractive index in the range 1.333–1.345. The developed hydrogels are highly transparent, showing transmittance >97%. FTIR study shows that the hydrogel was crosslinked by amide bond formation between HA and PEG, and between Coll and PEG. The rheological study shows that all the developed hydrogels exhibit viscoelastic behavior and all the hydrogels have storage modulus values (>100 pa) which is greater than loss modulus values—indicating sufficient elasticity for vitreous application. The elastic nature of the hydrogel increases with the increase in PEG concentration. The gel is formed in between 2 and 3 min—indicating its application in situ. The viscosity of the developed hydrogels shows shear thinning behavior. The pre-gel solution of the hydrogel is injectable through a 22 G needle—indicating its application in situ through vitrectomy surgery. All the hydrogels are hydrophilic and have water content of 96% approximately. Thus, the results show the positive properties for its application as a potential vitreous substitute.