PEG Mw Research Articles

Effect of Mild Conditions on PVA-Based Theta Gel Preparation: Thermal and Rheological Characterization.

Polyvinyl alcohol (PVA), possessing a strong ability to form hydrogels, has been widely used for various pharmaceutical and biomedical applications. In particular, the use of PVA-PEG in the form of theta gels for altered cartilage treatment has attracted an enormous amount of attention in the last 20 years. In this paper, we prepared 42 PVA-PEG in the form of theta gels at room temperature in an aqueous environment, testing the crystallization occurrence at basic pH (10 or 12). Using a statistical approach, the effect of PEG molecular weight, PVA molecular weight and alkaline pH values on water content and mechanical performance was evaluated. The used procedure permitted the theta gels to maintain swelling properties comparable to those of human cartilage, from 60% to 85%, with both polymers having the same influence. PEG MW mainly affected the hydrophilic properties, whereas the thermal properties were mostly influenced by the PVA. The shear and compression mechanical behavior of the produced materials were affected by both the polymers' MWs. The sample obtained using PVA 125 kDa with PEG 20 kDa as a porogen appeared to be the most suitable one for cartilage disease treatment, as it had an equilibrium shear modulus in the range of 50-250 kPa, close to that of native articular cartilage, as well as optimal mechanical response under compression along the entire analyzed frequency range with a mean value of 0.12 MPa and a coefficient of friction (COF) which remained under 0.10 for all the tested sliding speeds (mm/s).

An optimization of blocking agents for designing reliable electrochemical biosensors for ovarian cancer

Here, we report development of an electrochemical biosensor for ovarian cancer diagnosis using an optimized blocking agent for reliable performance of the device. The sensitivity, specificity and reproducibility of the device are negatively impacted by non-specific binding of molecules present in sample - proteins, DNA, RNA, small drug molecules, hormones etc, other than the analyte of interest bind to biorecognition molecule on the biosensor surface. Electrochemical biosensor was fabricated by functionalizing carbon screen printed electrodes with citrate-reduced gold nanoparticles followed by immobilization of 5′-amine modified ssDNA probe against miRNA 204 (ovarian can biomarker). To avoid or minimize non-specific binding, blocking reagent was optimized. Blocking reagents and methods are typically chosen in an empirical manner since a single standardized procedure has not been determined suitable for all applications. This paper presents the commonly used blocking buffers with varying molecular weights to minimize the non-specific binding process on the surface of the electrode. Here, three different blocking buffers are used - Bovine serum albumin (BSA; MW: 66430.3 kDa), Gelatin (MW: 40 kDa), and Polyethylene Glycol (PEG MW 4 kDa and 6 kDa). Additionally, different surfactants like tween20, Tritonx100, and HEPES buffer are used for preparation of blocking agents. Further, to evaluate the performance of different blocking agents, the sample of miRNA-204 is spiked in 0.01 M Phosphate buffer saline (PBS) and fetal bovine serum (FBS) were tested using chroamperometry. The difference in the saturation current was recorded for both curves obtained for 0.01 M PBS and FBS. Optimum blocking buffer 1% Gelatin in Tween20 was found to be giving negligible nonspecific binding for DNA based ovarian cancer biosensor.

A polymer electrolyte for rechargeable chloride ion batteries

• A poly(diallyl dimethyl ammonium chloride) (PDDAC) is proposed as an new electrolyte for chloride ion batteries. • The chloride ion conductivity is significantly varied by PEG plasticizer. • Chloride ion conductivity of 2.63 × 10 −5 S cm −1 is obtained at 303 K. • The chloride ion conducting capability is evidenced in a chloride ion battery. Chloride-ion batteries (CIBs) based on shuttling of chloride ion have recently attracted attention because of the safety, abundant resources, and high theoretical energy density. Herein, a polymer of poly(diallyl dimethyl ammonium chloride) (PDDAC) plasticized by poly(ethylene glycol) (PEG) is proposed as an new electrolyte for chloride ion batteries. The ionic conductivity of polymer electrolyte is significantly varied by the amount of plasticizer. A flexible, transparent polymer film with 70 wt% of PEG (Mw = 300) shows the highest chloride ion conductivity (2.63 × 10 −5 S cm −1 ) at 303 K. The chloride ion conducting capability is also evidenced in a lithium free chloride ion battery with CuCl as a cathode and Mg as an anode.

The fabrication of porous hollow polysulfone microspheres with PEG as a porogen for methylene blue adsorption

A porous hollow polysulfone (donated as PHPSF) microspheres were prepared by non-solvent-induced phase separation using PEG as a porogen. The influence of the molecular weights (Mw) of PEG on the morphology and porous structure of the microspheres were investigated. As the Mw of PEG increasing from 600 to 10,000 g·mol–1, the viscosity of the system increases, leading to the increase of the viscosity difference between the dispersed phase and the continuous phase, and a delay in phase separation. Hence, the diameter and shell thickness of the obtained microspheres increase with the porosity reducing. Moreover, when the Mw of PEG is below 4000, the low |Δδ| between PEG and solvent is conducive to the formation of microporous structure with narrow pore distribution. The as-prepared PHPSF microspheres exhibit a separation efficiency of 6 times for MB than that of the original PSF microspheres. In addition, a reusability of 5 times of PHPSF is achieved even in the harsh acid or alkali condition. These results clarify the relationship between the different Mw of PEGs and microspheres morphology. Therefore, this kind of PHPSF microspheres holds a promising for the water organic pollution treatment.

Conformation of poly(ethylene glycol) in aqueous cholinium amino acid hybrid solvents

HypothesisHybrid solvents based on cholinium amino acid ionic liquids ([Ch][AA] ILs) mixed with water are environmentally benign solvents with low toxicity. [Ch][AA] ILs are used in biomass pretreatment processes to dissolve targeted (macro)molecules such as lignin from lingnocellulose. Understanding how [Ch][AA] ILs dissolve polymers is therefore of great interest for the rational design of ILs towards industrial application. Variation of the IL anion and the water concentration are hypothesised to change the solvent properties of [Ch][AA] hybrid solvents. Therefore, we probe the solvent quality of [Ch][AA] aqueous solutions with different anions (glycinate, prolinate and argininate) and water concentration for the simple model solute poly(ethylene glycol) (PEG). ExperimentsPartial phase diagrams were produced to probe the salting-out effect of [Ch][AA] ILs towards PEG (Mw = 38 kDa). Small-angle neutron scattering experiments of deuterated PEG in hydrogenous [Ch][AA] aqueous solutions were performed to determine the polymer radius of gyration at infinite dilution (Rg,0) via Zimm-plots. Polymer concentration dependent apparent Rg values were obtained fitting an excluded volume polymer model onto the scattering data. Blends of hydrogenous and deuterated PEG under zero average contrast conditions were analysed to probe Rg at high polymer concentrations. FindingsHydrogen bond capacity of the anion is key to the salting-out effect of [Ch][AA] ILs on PEG. Rg,0 depends on anion species and water concentration. At IL:water = 1:30 (mole:mole) and 37 °C, cholinium argininate and cholinium glycinate are close to theta solvents while cholinium prolinate and dilute cholinium argininate (IL:water = 1:100) are between theta and good solvents.

Nano- and Micro-Porous Chitosan Membranes for Human Epidermal Stratification and Differentiation.

The creation of partial or complete human epidermis represents a critical aspect and the major challenge of skin tissue engineering. This work was aimed at investigating the effect of nano- and micro-structured CHT membranes on human keratinocyte stratification and differentiation. To this end, nanoporous and microporous membranes of chitosan (CHT) were prepared by phase inversion technique tailoring the operational parameters in order to obtain nano- and micro-structured flat membranes with specific surface properties. Microporous structures with different mean pore diameters were created by adding and dissolving, in the polymeric solution, polyethylene glycol (PEG Mw 10,000 Da) as porogen, with a different CHT/PEG ratio. The developed membranes were characterized and assessed for epidermal construction by culturing human keratinocytes on them for up to 21 days. The overall results demonstrated that the membrane surface properties strongly affect the stratification and terminal differentiation of human keratinocytes. In particular, human keratinocytes adhered on nanoporous CHT membranes, developing the structure of the corneum epidermal top layer, characterized by low thickness and low cell proliferation. On the microporous CHT membrane, keratinocytes formed an epidermal basal lamina, with high proliferating cells that stratified and differentiated over time, migrating along the z axis and forming a multilayered epidermis. This strategy represents an attractive tissue engineering approach for the creation of specific human epidermal strata for testing the effects and toxicity of drugs, cosmetics and pollutants.

Study of solid polyurethane electrolytes synthesized from HDI and PEO of different molecular weight

The development of solid polymer electrolyte (SPE) is important for the fabrication of safe and high performance lithium ion battery of the next generation. A series of polyurethanes (PUs) based SPEs synthesized from hexamethylene diisocyanate (HDI) and poly(ethylene glycol)s (PEGs) of varying molecular weight (MW = 300 ~ 1500 corresponding to PU03 ~ PU15) via one-step approach are investigated for the conductivity of lithium ion and other electrochemical properties. These synthetic PUs exhibit semi-crystalline structures when the MW of PEG is higher than 300, and turn into amorphous after the addition of LiClO4. The ionic conductivity decreases with the increasing concentration of LiClO4. The highest lithium ion conductivity was found to be 3.42 × 10−5 S/cm for PU15 with 10 wt% LiClO4 at 50 °C. However, its lithium ion transference number is low by 0.15. All of the PU-based SPEs containing 10 wt% LiClO4 are electrochemically stable up to 4.2 ~ 4.5 V versus Li+/Li, and show very good cycling stability in charge/discharge experiments. In the assembled battery with LiFePO4 as the cathode, PU15 displays higher performances than PU03, indicating good correlation to the molecular weight of PEG.

Effects of Polyethyelene Glycol-Desferrioxamine:Gallium Conjugates on Pseudomonas aeruginosa Outer Membrane Permeability and Vancomycin Potentiation.

Pseudomonas aeruginosa exhibits a broad spectrum of intrinsic antibiotic resistance because of the limited permeability of its outer membrane. Given this situation, molecules that could make Gram-negative bacteria more permeable and more susceptible to large-scaffold Gram-positive antibiotics may be advantageous. Herein, we evaluate the antimicrobial activity of a series of targeted poly(ethylene glycol)-desferrioxamine/gallium (PEG-DG) conjugates that can improve the sensitivity of P. aeruginosa to the glycopeptide vancomycin (VAN). We observed that single-ended mPEG-DG and double-ended PEG-DG2 conjugates characterized by PEG MW ≥2000 synergistically enhanced the sensitivity of VAN against P. aeruginosa reference strains PAO1 and ATCC 27853 and three clinically isolated carbapenem-resistant strains, but not Escherichia coli strain ATCC 25922. Although the exact mechanism of this phenomenon is currently under investigation, PEG-DG conjugates enhanced nitrocefin (NCF), hexidium iodide (HI), and VAN permeability only when PEG and DG were directly conjugated. The two most important physicochemical factors contributing to the synergistic activity observed with VAN relate to (1) the final concentration of DG ligands conjugated to the polymer and (2) the polymer length, wherein MW ≥2000 yielded a similar fractional inhibitory concentration.

Synthesis and Characterization of Maleic Anhydride Modified Poly (Ethylene Glycol) as Polymeric Solid-Solid Phase Change Materials

In this study, a novel type of polymeric solid-solid phase change materials (SSPCMs) and Maleic anhydride (MA) modified poly (ethylene glycol) PEG. MAM-PEG polymers were synthesized from different moleculer weight PEG (Mw: 4000, 6000) .On the other hand two different catalyst system was used; para toluene sulfonic acid (PTSA) and 1,8-Diazabicyclo [5.4.0] undec-7-ene (DBU).The PEG bound to the backbone of the polymers formed crystalline regions responsible from latent heat storage with reversible crystalline to amorphous phase transition as linked unit prevented total melting of the structure. Also MAM-PEG polyester polymers acid and hydroxyl values were determined for number of average molecular weight (Mn) and calculated as 36232 and 49020. Characterization and thermal properties of SSPCMs were performed by using fourier transform infrared (FT-IR) spectroscopy and differential scanning calorimetry (DSC) techniques mainly. DSC results showed that solid-solid transitions 36-54 °C temperature range and 163-153 Jg-1 enthalpy. As a result, MAM-PEG polymers were found potential for thermal energy storage (TES) applications.

Thermally induced physical gelation and phase transition of stereocomplexable poly(lactic acid)/poly(ethylene glycol) copolymers: Effects of hydrophilic homopolymers

Hydrophilic homopolymers in aqueous solution would play an important role on thermally induced physical gelation of stereocomplexable gels. Herein, the sol-gel transition, rheological behavior, crystalline structure and microstructure evolution of stereocomplexable copolymers composed of PLLA, PDLA and PEG in presence of PEG homopolymers have been systematically investigated. Ts-g of systems including PEG was much lower than that of enantiomeric mixtures. Ts-g was 36 °C after addition of PEG (Mn = 6 kg/mol), which was 6 °C below that of additive-free counterparts. The efficiency in reducing Ts-g was increased with increase of concentration of PEG, and depended on MW of PEG. Moreover, additives containing systems exhibited improved storage modulus, more compact packing of core-forming segments, larger inter-cluster distances and core radius. Essence of decrement of Ts-g by presence of PEG was the enhanced stereocomplex crystallization. This study illustrates that addition agents can serve as a regulator to modulate sol-gel transition behaviors of stereocomplexable systems.

Suitable Polymeric Coatings to Avoid Localized Surface Plasmon Resonance Hybridization in Printed Patterns of Photothermally Responsive Gold Nanoinks.

When using gold nanoparticle (AuNP) inks for writing photothermal readable secure information, it is of utmost importance to obtain a sharp and stable shape of the localized surface plasmon resonance (LSPR) absorption bands in the prints. The T increase at a given irradiation wavelength (ΔTλ) is the retrieved information when printed patterns are interrogated with a laser source. As ΔTλ is proportional to the absorbance at the wavelength λ, any enlargement or change of the absorbance peak shape in a printed pattern would lead to wrong or unreliable reading. With the aim of preparing AuNP inks suitable for inkjet printing of patterns with stable and reliable photothermal reading, we prepared liquid solutions of spherical AuNP coated with a series of different polymers and with or without additional dispersant. The optical stability of the inks and of the printed patterns were checked by monitoring the shape changes of the sharp LSPR absorption band of AuNP in the visible (λmax 519 nm) along weeks of ageing. AuNP coated with neutral polyethylenglycol thiols (HS-PEG) of mw 2000–20000 showed a strong tendency to rapidly agglomerate in the dry prints. The close contact between agglomerated AuNP resulted in the loss of the pristine shape of the LSPR band, that flattened and enlarged with the further appearance of a second maximum in the Near IR, due to plasmon hybridization. The tendency to agglomerate was found directly proportional to the PEG mw. Addition of the ethylcellulose (EC) dispersant to inks resulted in an even stronger and faster tendency to LSPR peak shape deformation in the prints due to EC hydrophobicity, that induced AuNP segregation and promoted agglomeration. The introduction of a charge on the AuNP coating revelead to be the correct way to avoid agglomeration and obtain printed patterns with a sharp LSPR absorption band, stable with ageing. While the use of a simple PEG thiol with a terminal negative charge, HS-PEGCOO(−) (mw 3000), was not sufficient, overcoating with the positively charged polyallylamine hydrochloride (PAH) and further overcoating with the negatively charged polystyrene sulfonate (PSS) yielded AuNP@HS-PEGCOO(−)/PAH(+) and AuNP@HS-PEGCOO(−)/PAH(+)/PSS(−), both giving stable prints. With these inks we have shown that it is possible to write photothermally readable secure information. In particular, the generation of reliable three-wavelength photothemal barcodes has been demonstrated.

Dual-Function Antibacterial Micelle via Self-Assembling Block Copolymers with Various Antibacterial Nanoparticles.

Antibacterial biomaterials with kill-resist dual functions by combining multiple active components have been constructed, with a final aim at decreasing the incidence of biomaterial-centered infection. Self-assemblies of bactericidal ZnO or Ag–ZnO nanoparticles (NPs) with triblock copolymers, poly(ethylene glycol)-b-poly(3-hydroxybutyrate-co-3-hydroxyvalerate)–poly(ethylene glycol) (PEG–PHBV–PEG), showed a hydrophobic PHBV layer on NPs with PEG segments exposed outside via hydrogen bonding, resulting in long PEG (Mw = 2000) aggregation and short PEG (Mw = 1000) aggregation, respectively. These nanocomposite aggregations released ZnO or Ag–ZnO rapidly within initial few hours, and about 42–45% of NPs were left in the nanocomposites in deionized water for 16 d to improve the long-term antibacterial activity further. At the concentration below 50 μg/mL, the nanocomposite aggregation was cell-compatible with ATDC5 and showed sterilization rates over 91% against Escherichia coli and 98% against Staphylococcus aureus. Long PEG aggregation showed greater cell proliferation capacity than short PEG aggregation, as well as better bacterial resistance and bactericidal activity against both E. coli and S. aureus. The flexible self-assembling antibacterial NPs with antifouling block copolymers via adjusting the component ratio or the segment length have shown premise in the construction of the dual-function antibacterial materials.

Amphiphilic PLGA‐PEG‐PLGA triblock copolymer nanogels varying in gelation temperature and modulus for the extended and controlled release of hyaluronic acid

ABSTRACTDifferent compositional parameters of poly(D,L‐lactic‐co‐glycolic acid)‐b‐poly(ethylene glycol) triblock copolymers (PLGA‐PEG) were varied to analyze their effect on gel formation and mechanical properties. Parameters such as hydrophilic/hydrophobic ratio (PLGA/PEG ratio), lactic acid/glycolic acid ratio (LA/GA ratio), PEG molecular weight (PEG Mw), polymer solution concentration, copolymer molecular weight (Mw), and polydispersity index (PDI) were studied in this work. For copolymers with PEG Mw of 1500 Da, gelation temperature (34–37 °C) was affected by D,L‐LA/GA ratio and Mw; while modulus was affected by LA/GA ratio, Mw, and Mn. Based on the parametric study, an injectable, thermoresponsive hyaluronic acid (HA) delivery platform was designed for ocular applications. PLGA‐PEG copolymers with D,L‐LA/GA ratio of 15/1, PLGA/PEG ratio of 2/1, PEG Mw of 1500 Da, and Mw of about 6 KDa gelled at 35 °C, were optically transparent, had a modulus less than 350 Pa and were used for HA release studies. This work also demonstrates, for the first time, an extended and controlled release of HA, beyond 2 weeks, from injectable hydrogels modified with a noncovalent interacting agent, poly(L‐lysine). Smaller PLL chains slowed down the HA release kinetics, while larger PLL chains produced a release profile similar to the nonmodified hydrogels. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48678.

High Drug Loading, Reversible Disulfide Core-Cross-Linked Multifunctional Micelles for Triggered Release of Camptothecin.

Nanomedicines in polymeric therapeutics present a potential treatment for cancers. However, their clinical effectiveness still has room to be improved. Herein, reduction-responsive reversibly core-cross-linked micelles based on the poly(ethylene glycol)-dihydrolipoic acid (MeO-PEG2k-DHLA) conjugate were developed for triggered intracellular release of camptothecin (CPT). Coupling two molecules of dihydrolipoic acid (DHLA) to methyl-terminated PEG (Mw 2000) through a labile ester bond was performed by solution-phase condensation reaction. Due to the amphiphilic property, the MeO-PEG2k-DHLA conjugate formed micelles that were readily cross-linked with disulfide formation dispersed in water. These sole cross-linked micelles were 74.9 nm in hydrodiameter, as analyzed by dynamic light scattering (DLS). The nanostructures demonstrated excellent stability against extensive dilution, while rapidly dissociating under 10 mM glutathione (GSH), highlighting their potential for drug delivery. Interestingly, CPT was modified with a disulfide linkage and subsequently conjugated to the MeO-PEG2k-DHLA polymer scaffold. Core-cross-linking of the micelles achieved high drug loading of CPT (31.81%, wt %) and demonstrated that CPT release at pH 7.4 was significantly declined by cross-linking (i.e., less than 15% release in 24 h), whereas more than 90% of CPT was released under 10 mM GSH condition. In vitro cellular uptake and MTT assays showed that CPT-conjugated MeO-PEG2k-DHLA micelles were effectively internalized into tumor cells to induce the cytotoxic effects against HepG-2 and MCF-7 cells. Importantly, in vivo pharmacokinetics analysis demonstrated the nanoscale feature of micelles makes CPT to present longer retention time, resulting in a higher accumulation at tumor sites. Taken together, the disulfide core-cross-linked MeO-PEG2k-DHLA multifunctional micelles with high drug loading and excellent stability are potential candidates for tumor-targeting drug delivery.

PEG-Peptide Inhibition of Scavenger Receptor Uptake of Nanoparticles by the Liver

PEGylated polylysine peptides represent a new class of scavenger receptor inhibitors that may find utility at inhibiting DNA nanoparticle uptake by Kupffer cells in the liver. PEG-peptides inhibit scavenger receptors in the liver by a novel mechanism involving in situ formation of albumin nanoparticles. The present study developed a new in vivo assay used to explore the structure-activity-relationships of PEG-peptides to find potent scavenger receptor inhibitors. Radio-iodinated PEG-peptides were dosed i.v. in mice and shown to saturate liver uptake in a dose-dependent fashion. The inhibition potency (IC50) was dependent on both the length of a polylysine repeat and PEG molecular weight. PEG30kda-Cys-Tyr-Lys25 was confirmed to be a high molecular weight (33.5 kDa) scavenger receptor inhibitor with an IC50 of 18 μM. Incorporation of multiple Leu residues improved potency, allowing a decrease in PEG MW and Lys repeat, resulting in PEG5kda-Cys-Tyr-Lys-(Leu-Lys4)3-Leu-Lys that inhibited scavenger receptors with an IC50 = 20 μM. A further decrease in PEG MW to 2 kDa increased potency further, resulting in a low molecular weight (4403 g/mol) PEG-peptide with an IC50 of 3 μM. Optimized low molecular weight PEG-peptides also demonstrated potency when inhibiting the uptake of radio-iodinated DNA nanoparticles by the liver. This study demonstrates an approach to discover low molecular weight PEG-peptides that serve as potent scavenger receptor inhibitors to block nanoparticle uptake by the liver.

Dipeptide-modified nanoparticles to facilitate oral docetaxel delivery: new insights into PepT1-mediated targeting strategy

Oligopeptide transporter 1 (PepT1) has been a striking prodrug-designing target. However, the underlying mechanism of PepT1 as a target to facilitate the oral absorption of nanoparticles (NPs) remains unclear. Herein, we modify Poly (lactic-co-glycolic acid) (PLGA) NPs with the conjugates of dipeptides (L-valine-valine, L-valine-phenylalanine) and polyoxyethylene (PEG Mw: 1000, 2000) stearate to facilitate oral delivery of docetaxel (DTX) to investigate the oral absorption mechanism and regulatory effects on PepT1 of the dipeptide-modified NPs. The cellular uptake of the dipeptide-modified NPs is more efficient than that of the unmodified NPs in the stably transfected hPepT1- Hela cells and Caco-2 cells, suggesting the involvement of PepT1 in the endocytosis of NPs. The internalization of the dipeptide-modified NPs is proved to be a proton-dependent process. Moreover, the L-valine-valine modified NPs with shorter PEG chain exhibit distinct advantages in terms of intestinal permeability and oral absorption, resulting in significantly improved oral bioavailability of DTX. In summary, PepT1 could serve as a desirable target for oral nanoparticulate drug delivery and the dipeptide-modified NPs represent a promising nanoplatform to facilitate oral delivery of hydrophobic drugs with low bioavailability.

Effect of plasticizer poly(ethylene glycol) on the crystallization properties of stereocomplex-type poly (lactide acid)

The effects of the plasticizer poly(ethylene glycol) (PEG) on crystallization properties of equimolar poly(L-lactide) (PLLA)/poly(D-lactide) (PDLA) blends were investigated. Formation of the stereocomplex-type poly(lactide acid) (sc-PLA) crystallites was confirmed by Wide-angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC) analyses. Sc-PLA crystallites without any homochiral poly(lactide acid) (hc-PLA) formed, as the result of the incorporation of the plasticizer PEG (more than or equal to 10%(wt)) at a processing temperature (240 °C). Moreover, when the M W of PEG reached 1 000 g · mol–1, the crystallizability of stereocomplex crystallites was the best. Isothermal crystallization kinetics further revealed that PEG could accelerate the crystallization rate of sc-PLA, with the optimum crystallization kinetic parameters being obtained at 10% (wt) PEG. Several crystallization kinetics equations were applied to describe the effect of PEG on the crystallization behavior of sc-PLA. The influence of PEG on the spherocrystal morphologies of sc-PLA was also investigated using polarized optical microscopy.

Ibuprofen-loaded micelles based on star-shaped erythritol-core PLLA-PEG copolymer: effect of molecular weights of PEG

Amphiphilic star-shaped copolymers based on star-shaped poly(L-lactide) (s-PLLA) and poly(ethylene glycol) (PEG) (s-PLLA-PEG) were synthesized with variable molecular weights (Mw) of PEG, and the relationship between the PEG block molecular weight of s-PLLA-PEG copolymers and their micelle properties were investigated. The structure and Mw of s-PLLA-PEG were characterized with 1H NMR, GPC, DSC, and XRD. The ibuprofen (IBU)-loaded s-PLLA-PEG micelles were prepared by dialysis method. The effects of PEG block molecular weight on the morphology, particle size, zeta potential, drug loading content (LC), drug encapsulation efficiency (EE), and in vitro drug release behavior of prepared micelles were investigated. Results indicated that the average diameters, LC, and EE of IBU-loaded s-PLLA-PEG micelles increased with increasing the Mw of PEG in s-PLLA-PEG copolymers. The in vitro study showed that the IBU accumulative release can be depressed by increasing the Mw of the s-PLLA-PEG, and the release profiles of IBU from s-PLLA-PEG followed the Baker-Lonsdale model equation. The results suggest that structural tailoring of PEG length from s-PLLA-PEG copolymers could provide a new strategy for designing drug carriers of high efficiency.

Improved processability and performance of biomedical devices with poly(lactic acid)/poly(ethylene glycol) blends

ABSTRACTTo improve the processability of micropolymer‐based devices used for biomedical applications, poly(lactic acid) (PLA) was melt‐blended with poly(ethylene glycol)s (PEGs) of different molecular weights (MWs; weight‐average MWs = 200, 800, 2000, and 4000; these PEGS are referred to as PEG200, PEG800, PEG2000, and PEG4000, respectively, in this article). The thermal properties, mechanical properties, and rheological properties of the PLA and the PLA–PEG blends were investigated. The tensile samples’ morphologies showed that the low‐MW PEGs filled molds well. The rheological properties confirmed that the low‐MW PEGs decreased the complex viscosity, and improved the processability. With decreasing PEG MW, the PLA glass‐transition temperature decreased. The nanoindenter data show that the addition of PEG decreased the modulus and hardness of PLA. The morphologies of the tensile samples showed that with increasing PEG MW, the thicknesses of the core layers increased gradually. The elongation at break was improved by approximately 247% with the addition of PEG200. Such methods can produce easily processed biological materials for producing biomedical products. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45194.

Plasmid DNA affinity partitioning using polyethylene glycol - sodium sulfate aqueous two-phase systems.

Extraction of plasmid DNA (pDNA) from an alkaline bacterial cell lysate has been investigated using partitioning and affinity partitioning in aqueous two-phase systems (ATPSs) containing 12% (w/w) polyethylene glycol and 12% (w/w) sodium sulfate. In this work, a modified 20bp pyrimidine oligonucleotide acting as a triplex-forming oligonucleotide (TFO) was employed as an affinity ligand to improve the partition behavior. The pUC118 plasmid was chosen to be extracted because of its specific oligonucleotide recognition sequence. In order to find the proper conditions, operational parameters such as PEG molecular weight, pH and lysate load were also studied. The results showed that adding the affinity ligand strongly changed the partitioning behavior of pDNA without any considerable impact on the partitioning of RNA and protein content. The best achieved result was at pH=6 and PEG MW of 600Da and 60% of lysate load. In these conditions, 67% of pDNA was recovered in the top phase while the contaminants mainly accumulated in the bottom phase.