Higher PEG Content Research Articles

A Sacrificial PLA Block Mediated Route to Injectable and Degradable PNIPAAm-Based Hydrogels.

Thermoresponsive poly(N-isopropylacrylamide) (PNIPAAm)-based injectable hydrogels represent highly attractive materials in tissue engineering and drug/vaccine delivery but face the problem of long-term bioaccumulation due to non-degradability. In this context, we developed an amphiphilic poly(D,L-lactide)-b-poly(NIPAAm-co-polyethylene glycol methacrylate) (PLA-b-P(NIPAAm-co-PEGMA)) copolymer architecture, through a combination of ring-opening and nitroxide-mediated polymerizations, undergoing gelation in aqueous solution near 30 °C. Complete hydrogel mass loss was observed under physiological conditions after few days upon PLA hydrolysis. This was due to the inability of the resulting P(NIPAAm-co-PEGMA) segment, that contains sufficiently high PEG content, to gel. The copolymer was shown to be non-toxic on dendritic cells. These results thus provide a new way to engineer safe PNIPAAm-based injectable hydrogels with PNIPAAm-reduced content and a degradable feature.

Mechanistic investigation of bead-based padlock rolling circle amplification under molecular crowding conditions

We present a mechanistic investigation of bead-based padlock rolling circle amplification (RCA) under molecular crowding conditions, a sensitive and selective DNA detection method we have developed. Several important points to optimize the method were clarified: (i) the increase in the number of RCA products is proportional to the excluded volume of poly(ethylene glycol) (PEG), (ii) PEG facilitates ligation of padlock probe to form circular concatemers and monomers, both of which may act as a template for RCA, and (iii) hybridization of detection probe to the products may be facilitated at higher PEG concentrations.

Improving the perm-selectivity and anti-fouling property of UF membrane through the micro-phase separation of PSf-b-PEG block copolymers

PSf-b-PEG block copolymers with different PEG contents were synthesized to fabricate the highly perm-selective and anti-fouling ultrafiltration (UF) membranes. PEG homopolymer was also blended into the polysulfone casting solutions to fabricate the control (PSf/PEG blend) membranes. The membrane pore structure, surface properties and separation performances of PSf-b-PEG block copolymer membranes and PSf/PEG blend membranes were investigated to identify the role of PEG block for the pore formation. Our results find that the higher PEG content in the PSf-b-PEG block copolymer and in the PSf/PEG blend system was favorable to form more pores and thinner top skin layer with the slightly larger pore size and the higher MWCO of the fabricated membranes. But under the same content, PEG in the block copolymer could help to generate more pores but with similar pore size than PEG in the blend system during the phase-inversion process, which is because of the micro-phase separation of PSf block and PEG block. The fabricated PSf-b-PEG21 (PSf-b-PEG having 21 wt% PEG) membrane had a high water permeation coefficient of 980.0 ± 33.0 LMH/bar and a high BSA rejection above 98%, succeeding the current perm-selectivity upper-bound of the reported polymeric UF membranes. Antifouling experiments confirmed that the PSf-b-PEG21 membrane exhibited a slow and less flux decline during the fouling stage, but a fast and high flux recovery after the backwash cleaning. Our work provides some insights on the relationship of PSf-b-PEG block copolymer composition and membrane structure-separation properties.

Denaturation studies of Clarias gariepinus glutathione transferase in dilute and crowded solutions.

It is important to understand the effect of crowding conditions on the native structure and functional state of enzymes. Equilibrium denaturation studies of Clarius gariepinus GST (CgGST) by guanidine hydrochloride (GdHCl) under dilute conditions and in separate solutions of 0-100gdm-3 Ficoll 70, polyethylene glycol 6000 (PEG 6000) and equal w/v mixtures of the two polymers at 25°C and pH 7.4 were studied fluorometrically. The data were analyzed based on a two-state model assuming the native protein dimer separates into two monomers and then unfolds. The standard free energy of unfolding (ΔG°UN) increases with increasing concentration of each crowding agent in a manner suggesting that high concentrations of PEG 6000 and Ficoll 70 favour the native CgGST relative to the unfolded form. Ficoll 70 stabilizes the native CgGST better than PEG 6000 at low w/v concentration. A mixture of equal g/cm3 concentrations of both crowding agents, however, stabilizes the native form more effectively than either Ficoll 70 or PEG 6000 at equivalent w/v total concentration and is less sensitive to GdHCl. This is in strong agreement with the results of refolding studies, and suggests that a mixture of molecular crowders of widely different molecular weights might show enhanced excluded volume effects compared to a single crowder. Thus, mixed crowding agents more effectively protect the enzyme against denaturation and assist in renaturation better than a single crowder. This suggests a heterogeneous solution of crowders, as will be found within cells, enhances the beneficial effect of crowding on the folded protein stability.

Temperature-Activated PEG Surface Segregation Controls the Protein Repellency of Polymers.

Poly(ethylene glycol) (PEG) is widely used to modulate the hydration states of biomaterials and is often applied to produce nonfouling surfaces. Here, we present X-ray scattering data, which show that it is the surface segregation of PEG, not just its presence in the bulk, that makes this happen by influencing the hydrophilicity of PEG-containing substrates. We demonstrate a temperature-dependent trigger that transforms a PEG-containing substrate from a protein-adsorbing to a protein-repelling state. On films of poly(desaminotyrosyl-tyrosine-co-PEG carbonate) with high (20 wt %) PEG content, in which very little protein adsorption is expected, quartz crystal microbalance data showed significant adsorption of fibrinogen and bovine serum albumin at 8 °C. The surface became protein-repellent at 37.5 °C. When the same polymer was iodinated, the polymer was protein-adsorbent, even when 37 wt % PEG was incorporated into the polymer backbone. This demonstrates that high PEG content by itself is not sufficient to repel proteins. By inhibiting phase separation either with iodine or by lowering the temperature, we show that PEG must phase-separate and bloom to the surface to create an antifouling surface. These results suggest an opportunity to design materials with high PEG content that can be switched from a protein-attractant to a protein-repellent state by inducing phase separation through brief exposure to temperatures above their glass transition temperature.

Chlorogenic Acid Entrapped in Hybrid Materials with High PEG Content: A Strategy to Obtain Antioxidant Functionalized Biomaterials?

The formation of pro-oxidant species after implantation of biomaterials could be responsible for the failure of the implant itself, because of oxidative stress-induced damage. In this work, the SiO2/polyethylene glycol (PEG)/chlorogenic acid (CGA) hybrids synthesized by the sol–gel method with 50 wt% of the polymer and different amounts of CGA (5, 10, 15 and 20 wt%) were studied. The hybrids soaked in simulated body fluid (SBF) showed the formation of hydroxyapatite layers on their surface, suggesting that the hybrids are bioactive. Their radical scavenging capacity towards DPPH· and ABTS·+ (2,2′-Azino-bis(3-ethylbenzthiazoline-6-sulfonic acid), evaluated at three different doses (0.5, 1 and 2 mg), showed probe- and dose-dependent behavior. In addition, the antioxidant properties of CGA were not affected by the presence of high amounts of the polymer. The in vitro biocompatibility in three cell lines (NIH 3T3, HaCaT and SH-SY5Y) was assessed by using the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. Apart from SH-SY5Y, the cell viability—expressed as mitochondrial redox activity percentage of cells directly exposed to powders—and morphology was not affected, suggesting that the hybrids have the ability to interfere and act selectively against tumor cells. The antibacterial properties of the different materials against Escherichia coli and Enterococcus faecalis were affected by different amounts of the natural antioxidant component.

Mechanical Properties and Concentrations of Poly(ethylene glycol) in Hydrogels and Brushes Direct the Surface Transport of Staphylococcus aureus.

Surface-associated transport of flowing bacteria, including cell rolling, is a mechanism for otherwise immobile bacteria to migrate on surfaces and could be associated with biofilm formation or the spread of infection. This work demonstrates how the moduli and/or local polymer concentration play critical roles in sustaining contact, dynamic adhesion, and transport of bacterial cells along a hydrogel or hydrated brush surface. In particular, stiffer more concentrated hydrogels and brushes maintained the greatest dynamic contact, still allowing cells to travel along the surface in flow. This study addressed how the mechanical properties, molecular architectures, and thicknesses of minimally adhesive poly(ethylene glycol) (PEG)-based coatings influence the flow-driven surface motion of Staphylococcus aureus MS2 cells. Three protein-repellant PEG-dimethylacrylate hydrogel films (∼100 μm thick) and two protein-repellant PEG brushes (8-16 nm thick) were sufficiently fouling-resistant to prevent the accumulation of flowing bacteria. However, the rolling or hopping-like motions of gently flowing S. aureus cells along the surfaces were specific to the particular hydrogel or brush, distinguishing these coatings in terms of their mechanical properties (with moduli from 2 to 1300 kPa) or local PEG concentrations (in the range 10-50% PEG). On the stiffer hydrogel coatings having higher PEG concentrations, S. aureus exhibited long runs of surface rolling, 20-50 μm in length, an increased tendency of cells to repeatedly return to some surfaces after rolling and escaping, and relatively long integrated contact times. By contrast, on the softer more dilute hydrogels, bacteria tended to encounter the surface for brief periods before escaping without return. The dynamic adhesion and motion signatures of the cells on the two brushes were bracketed by those on the soft and stiff hydrogels, demonstrating that PEG coating thickness was not important in these studies where the vertically oriented surfaces minimized the impact of gravitational forces. Control studies with similarly sized poly(ethylene oxide)-coated rigid spherical microparticles, that also did not arrest on the PEG coatings, established that the bacterial skipping and rolling signatures were specific to the S. aureus cells and not simply diffusive. Dynamic adhesion of the S. aureus cells on the PEG hydrogel surfaces correlated well with quiescent 24 h adhesion studies in the literature, despite the orientation of the flow studies that eliminated the influence of gravity on bacteria-coating normal forces.

Will a water gradient in oral mucosa affect transbuccal drug absorption?

Formulations for buccal drug delivery often comprise polymers to facilitate mucoadhesion based on water sorption. The main objective of the current study was therefore to evaluate the effect of dehydration on drug uptake through oral mucosa. We have used diffusion cells with excised porcine mucosa to study uptake of three alternative drugs (i.e., Metronidazole, Benzydamine and Xylometazoline) together with polyethylene glycol (PEG) as the model polymer for adjusting water activity in the test solutions. Taking drug activity into account, we can conclude that addition of PEG results in a drug flux through mucosa that is about two times lower for Metronidazole and more than 40 times lower for Xylometazoline compared to that from a pure PBS-solution. However, for Benzydamine the uptake through mucosa was more or less the same, which could possibly be due to the high PEG-concentration (65 wt%) affecting the dissociation constant and thus the permeability. These results indicate that an increased water gradient may have the same limiting effect on permeability through oral mucosa as previously seen for skin. Thus, water gradient effects should be a factor to consider when developing buccal adhesive formulations.

Effect of Drought on Seed Germination and Early Seedling of Tomato Genotypes using Polyethylene Glycol 6000

Tomato is a sensitive crop to a variety of environmental stresses, especially drought. Therefore, the objective of the present work was to screen for drought tolerance at seed and seedling (vegetative) levels for better understanding of drought mechanisms and identification and selection of the most tolerant tomato genotypes. Twenty four (24) tomato genotypes were screened for drought tolerance using 0%, 4% and 14% polyethylene glycol 6000 (PEG 6000). The experiment was laid in complete randomized design with three replication and three treatments. The following parameters: germination percentage, shoot length, root length, shoot and root weight and recovery date were recorded in the course of the experiment. There was no significant difference in germination percentage between control and low PEG. However, significant differences were observed between control and low concentration of PEG when compared to high PEG concentration. Water stress created by PEG 6000 at high concentration (14%) significantly reduced all the parameters measured in all the genotypes. Overall, NGB01357, L00170 and NHGB/09/113 performed better under drought conditions and could be very vital in breeding program.

Influence of biostimulants-seed-priming on Ceratotheca triloba germination and seedling growth under low temperatures, low osmotic potential and salinity stress

Extreme temperatures, drought and salinity stress adversely affect seed germination and seedling growth in crop species. Seed priming has been recognized as an indispensable technique in the production of stress-tolerant plants. Seed priming increases seed water content, improves protein synthesis using mRNA and DNA and repair mitochondria in seeds prior to germination. The current study aimed to determine the role of biostimulants-seed-priming during germination and seedling growth of Ceratotheca triloba (Bernh.) Hook.f. (an indigenous African leafy vegetable) under low temperature, low osmotic potential and salinity stress conditions. Ceratotheca triloba seeds were primed with biostimulants [smoke-water (SW), synthesized smoke-compound karrikinolide (KAR1), Kelpak® (commercial seaweed extract), phloroglucinol (PG) and distilled water (control)] for 48h at 25°C. Thereafter, primed seeds were germinated at low temperatures, low osmotic potential and high NaCl concentrations. Low temperature (10°C) completely inhibited seed germination. However, temperature shift to 15°C improved germination. Smoke-water and KAR1 enhanced seed germination with SW improving seedling growth under different stress conditions. Furthermore, priming seeds with Kelpak® stimulated percentage germination, while PG and the control treatment improved seedling growth at different PEG and NaCl concentrations. Generally, high concentrations of PEG and NaCl brought about detrimental effects on seed germination and seedling growth. Findings from this study show the potential role of seed priming with biostimulants in the alleviation of abiotic stress conditions during seed germination and seedling growth in C. triloba plants.

Enhancement of CO2 capture by polyethylene glycol-based polyurethane membranes

Poly (ethylene glycol) (PEG)-based polyurethane (PU) membranes are attractive materials for CO2 separation from various sources such as flue gas and syngas. However, the strong tendency of PEG chains to crystallize leads to reduced permeability of the membrane. Here, we developed new types of PU chemistries with high PEG content and reduced crystallinity. A series of PUs were synthesized based on mixtures of PEG and poly (propylene glycol) (PPG), and various PEG-PPG triblock copolymers (PEG-b-PPG). The presence of PEG-b-PPG triblock copolymers combines the high selectivity of PEG while the PPG pendant methyl group hinders local crystallization. The resulting membranes showed CO2 permeability of 144 barrer and high CO2/N2 and CO2/H2 selectivities up to 54 and 8.3, respectively. Due to the absence of the crystalline soft phase, synthesized PUs with PEG-b-PPG triblock copolymers exhibit higher chain flexibility which is reflected by a decrease in the glass transition temperature of the soft segments. In contrast, the mixture of PEG and PPG showed minimal effects on the crystallinity of PEG domains. This resulted in lower membrane gas separation performance where CO2 permeability and CO2/H2 selectivity decreased to 68 barrer and 4.9, respectively.

Surface PEG Grafting Density Determines Magnetic Relaxation Properties of Gd-Loaded Porous Nanoparticles for MR Imaging Applications.

Surface PEGylation of nanoparticles designed for biomedical applications is a common and straightforward way to stabilize the materials for in vivo administration and to increase their circulation time. This strategy becomes less trivial when MRI active porous nanomaterials are concerned as their function relies on water/proton-exchange between the pores and bulk water. Here we present a comprehensive study on the effects of PEGylation on the relaxometric properties of nanozeolite LTL (dimensions of 20 × 40 nm) ion-exchanged with paramagnetic GdIII ions. We evidence that as long as the surface grafting density of the PEG chains does not exceed the “mushroom” regime (conjugation of up to 6.2 wt % of PEG), Gd-LTL retains a remarkable longitudinal relaxivity (38 s–1 mM–1 at 7 T and 25 °C) as well as the pH-dependence of the longitudinal and transverse relaxation times. At higher PEG content, the more compact PEG layer (brush regime) limits proton/water diffusion and exchange between the interior of LTL and the bulk, with detrimental consequences on relaxivity. Furthermore, PEGylation of Gd-LTL dramatically decreases the leakage of toxic GdIII ions in biological media and in the presence of competing anions, which together with minimal cytotoxicity renders these materials promising probes for MRI applications.

Molecular simulation and experimental studies of the miscibility of polylactic acid/polyethylene glycol blends

Computer simulation and experiments were performed to investigate the miscibility of PLA/PEG blends with different PEG concentrations. Flory-Huggins interaction (χ) parameter used to predict the miscibility for the blends was estimated by molecular dynamic simulation of fully atomistic model. The calculated χ parameter and radial distribution function suggest that the PLA and PEG blends are likely miscible at low PEG concentrations (10–30 wt%), but they become apparently immiscible at higher PEG content (>50 wt%). This result is consistent with density distribution of PLA and PEG beads calculated from dissipative particle dynamics simulation of coarse-grained model. To support the computational results, experiments based on differential scanning calorimetry (DSC) and rheometry were also performed. The DSC thermograms of 90:10, 80:20, and 70:30 (wt/wt) of PLA/PEG blends showed a single glass transition and PLA melting peak, indicating PLA/PEG is miscible over this composition. In rheometry, frequency (ω) dependence of storage moduli (G′) at low frequencies for 75:25 and 70:30 blends indicate that these samples are near the phase separation point.

Preparation and characterization of polyethylene glycol/poly(L-lactic acid) blends

Abstract The effect of incorporation of poly(ethylene glycol) (PEG) on thermomechanical and hydrophilicity properties of poly(L-lactic acid) (PLLA) was investigated. PEG/PLLA blends, containing 10, 20, 30 and 40 wt% PEG, were prepared by melt-extrusion in a co-rotating twin-screw extruder. By DSC analysis, it was observed that the Tg of PLLA phase in PEG/PLLA blends decreased accompanied by a significant decrease in Tcc and increase in their melting enthalpy. Therefore, the addition of PEG enhances the crystallization ability of PLLA phase due to its lubricating effect which increased mobility of PLLA chains. From TGA it was observed that low concentrations of PEG (10 & 20 wt%) increase the Tonset of thermal degradation, probably due to improved heat resistance of the crystalline phase. At higher PEG content, the Tonset decreases, as the lubricating effect becomes the controlling mechanism for the initiation of degradation process. Decrease in tensile strength and modulus was recorded especially in PLLA blends with PEG content higher than 20 wt%. The elongation at break decreases reaching a maximum at 20 wt% PEG and then dropped again. To investigate the effect of PEG on the wetting ability of PLLA, water contact angle measurements were performed. The results indicate that the introduction of PEG lowers the contact angle values in PEG/PLLA film surfaces, as compared to pure PLLA, suggesting improved hydrophilic properties.

Porous gelatin/poly(ethylene glycol) scaffolds for skin cells

ABSTRACTBiocompatible porous polymeric scaffolds provide a suitable environment for proliferation of stem cells in human body. In this research work, porous gelatin – poly(ethylene glycol), PEG, based scaffolds were prepared using combination of freeze-gelation and freeze-extraction methods. Effects of various parameters such as freezing temperature, cross-linking agent, concentrations of gelatin and PEG and their blending ratio on physical and mechanical properties, swelling ratio, porosity, pore size, and degradation rate of scaffolds were investigated. Also, proliferation of fibroblast skin cells on the scaffolds was examined by MTS assay to assess the suitability of the scaffolds in wound healing and skin regeneration. The mean pore diameters of the scaffolds ranged from 100 to 182 µm. The scaffolds with higher PEG content possessed larger pore size. On the contrary, the scaffolds prepared from higher solution concentration had smaller mean pore size, and the pores were mostly interconnected. The latter scaffolds had good mechanical properties. Addition of PEG contributed to softness of the scaffolds as well. The water uptake capacity of the scaffolds was higher with larger pore size and higher pore interconnectivity. The scaffolds were biocompatible with human skin fibroblast cells and showed high growth level of the cells.

Effects of Terminal Sterilization on PEG-Based Bioresorbable Polymers Used in Biomedical Applications.

The effects of ethylene oxide (EO), vaporized hydrogen peroxide (VHP), gamma (γ) radiation, and electron-beam (E-beam) on the physiochemical and morphological properties of medical device polymers are investigated. Polymers with ether, carbonate, carboxylic acid, amide and ester functionalities are selected from a family of poly(ethylene glycol) (PEG) containing tyrosine-derived polycarbonates (TyrPCs) to include slow, medium, fast, and ultrafast degrading polymers. Poly(lactic acid) (PLA) is used for comparison. Molecular weight (Mw) of all tested polymers decreases upon gamma and E-beam, and this effect becomes more pronounced at higher PEG content. Gamma sterilization increases the glass transition temperature of polymers with high PEG content. EO esterifies the carboxylic acid groups in desaminotyrosol-tyrosine (DT) and causes significant degradation. VHP causes hydroxylation of the phenyl ring, and hydrolytic degradation. This study signifies the importance of the chemical composition when selecting a sterilization method, and provides suggested conditions for each of the sterilization methods.

Influence of exogenous 5-aminolevulinic acid on chlorophyll synthesis and related gene expression in oilseed rape de-etiolated cotyledons under water-deficit stress

5-aminolevulinic acid (ALA) is an essential precursor for the biosynthesis of tetrapyrrols such as heme and chlorophyll (Chl). Previous studies have focused mainly on promotive effects of exogenous ALA on plant growth, while regulatory mechanisms affecting Chl biosynthesis have been only partially discussed. In the present study, the ameliorative role of exogenous ALA was investigated on Chl and endogenous ALA biosynthesis in six-day-old etiolated oilseed rape (Brassica napus L.) cotyledons during the de-etiolation stage. We showed that exogenously applied ALA of a low dosage enhanced Chl and ALA accumulation in cotyledons, while 600 µM ALA treatment inhibited the accumulation of Chl and ALA severely. However, the gene expression levels of glutamyl-tRNA reductase (HEMA) and glutamate-1-semialdehyde aminotransferase (GSA) were not affected under either low or high ALA concentrations. Furthermore, water deficit induced by polyethylene glycol 6000 (PEG) suppressed the Chl and ALA accumulation in cotyledons, while the inhibition was partially alleviated in the cotyledons pretreated with ALA. The decrease in Chl biosynthesis induced by PEG stress was assumed to be related to downregulation of HEMA and Mg-chelatase ChlH (ChlH), and upregulation of ferrochelatase (FC) genes. Moreover, exogenously applied ALA did not show any effect on the expression of Chl synthesis-related genes under the PEG treatment. These results showed a difference in suppressing ALA synthesis due to the high concentration of ALA and PEG. Exogenously applied ALA did not affect the expression of HEMA and GSA, thus exogenous ALA regulated Chl synthesis not via the regulation of transcriptional level in ALA biosynthesis. However, the inhibition in Chl and endogenous ALA accumulation by the PEG treatment may be attributed to downregulation of HEMA and ChlH, and upregulation of FC.

The effect of PEG length on the size and guest uptake of PEG-capped MIL-88A particles.

The surface functionalization of MOF particles with poly(ethylene glycol) (PEG) is important for their use in biomedical applications. Here, the effect of the molecular weight of a monovalent PEG-carboxylate capping ligand (MWPEG) was investigated in a newly developed one-step, stoichiometric procedure that aims at functionalizing MIL-88A particles and achieving size control at the same time. The bulk of the MIL-88A particles is composed of iron(iii) oxide metal clusters connected by fumaric acid as the organic ligand. The surface is functionalized with monovalent PEG-carboxylate capping ligands of different lengths. The size of the PEG-functionalized MIL-88A decreased with increasing MWPEG, and nanoMOFs were obtained for long (≥2 kDa) PEG chains. For lower MWPEG, higher concentrations of PEG were needed to obtain the maximum size effect, but the resulting sizes were still larger than for long PEGs. BET surface area, elemental analysis, zeta potential, and infrared spectroscopy measurements showed that the PEG chains were attached to the surface of the MOF particles and not in their interior. Moreover, it was demonstrated that longer chains occupy a larger surface area, and the PEG chains adopt the low-density brush conformation. Uptake and release experiments with sulforhodamine B dye (as a model drug) showed a higher and faster uptake and release for MIL-88A functionalized with PEG (20 kDa) than for native MIL-88A, which is attributed to a larger surface-to-volume ratio for the PEG-covered particles, and to the well-hydrated and accessible nature of the PEG layer in an aqueous medium. Complete release of the dye was achieved in phosphate buffered saline, the majority by counter ion exchange, and a smaller fraction in the salt form.

Striking Dispersion of Recrystallized Poly(ethylene glycol)-Poly(lactic acid) Solvent-Casting Blend

The solvent casted poly(ethylene glycol) (PEG) and poly(lactic acid) (PLA) blend was recrystallized by the thermal treatment of a heating and cooling cycle. The high PEG content blend (30 wt%) showed a striking dispersion behavior, that the materials rapidly dispersed and dissolved in the aqueous environment in a few hours. This phenomenon has not been reported by others, and was not observed in low PEG content samples of 5%, 10%, and 20%, or quenched(amorphous) samples. We hypothesized the mechanism that the chain rearrangement during the thermal treatment leads to the phase separation. And with the phase separation in the recrystallized samples, the PEG potions rapidly dissolved in the aqueous environment, left out the small PLA spherulites being separated and dispersed in the solution. The same underlying reason can also be inferred from the degradation behaviors of other samples. Characterizations of DSC, XRD, and SEM have been done to validate our hypothesis.

Near IR fluorescent conjugated poly(ethylene glycol)bisphosphonate nanoparticles for in vivo bone targeting in a young mouse model.

Bisphosphonate (BP) compounds are widely used in the treatment of bone disorders. This group of drugs with a high affinity to Ca+2 ions is rapidly attracted to bone mineral, especially in areas of high resorption. We have engineered unique biodegradable BP nanoparticles (NPs) by dispersion co-polymerization of the monomers methacrylate-PEG-BP) and (3-Aminopropyl)mathacrylamide) with the crosslinker monomer tetra ethylene glycol diacrylate. These NPs possess a dual functionality: (1) covalent attachment of a dye (e.g. near IR dye) or a drug to the nanoparticles through the primary amine groups on the surface of the NPs; (2) chelation to the bone mineral hydroxyapatite through the BP on the surface of the NPs. This study describes the uptake of the unique near IR fluorescent Cy 7-conjugated BP NPs in bone of a young mouse model. Blood half-life studies revealed a relatively long half-life (approximately 5 h) due to a high concentration of PEG in the BP NPs as well as a relatively long whole body clearance (approximately 2 weeks). Body distribution studies showed a specific uptake of the BP NPs in bone. These unique engineered BP NPs are planned to be utilized in future work for diagnostic and drug delivery systems that are targeted to bone disorders.