Mechanism Of Poly Research Articles

EUV ablation of organic polymers at a high fluence

Abstract A preliminary investigation on short-wavelength ablation mechanisms of poly(methyl methacrylate) (PMMA) and poly (1,4-phenylene ether ether-sulfone) (PPEES) by extreme ultraviolet (EUV) radiation at 13.5 nm using a table-top laser-produced plasma from a gas-puff target at LLG (Göttingen) and at 46.9 nm by a 10 Hz desktop capillary discharge laser operated at the Institute of Physics (Prague) is presented. Ablation of polymer materials is initiated by photo-induced polymer chain scissions. The ablation occurs due to the formation of volatile products by the EUV radiolysis removed as an ablation plume from the irradiated material into the vacuum. In general, cross-linking of polymer molecules can compete with the chain decomposition. Both processes may influence the efficiency and quality of micro(nano)structuring in polymer materials. Wavelength is a critical parameter to be taken into account when an EUV ablation process occurs, because different wavelengths result in different energy densities in the near-surface region of the polymer exposed to nanosecond pulses of intense EUV radiation.

Polyinosinic-polycytidylic acid has therapeutic effects against cerebral ischemia/reperfusion injury through the downregulation of TLR4 signaling via TLR3.

Recent reports have shown that preconditioning with the TLR3 ligand polyinosinic-polycytidylic acid (poly(I:C)) protects against cerebral ischemia/reperfusion (I/R) injury. However, it is unclear whether poly(I:C) treatment after cerebral I/R injury is also effective. We used mouse/rat middle cerebral artery occlusion and cell oxygen-glucose deprivation models to evaluate the therapeutic effects and mechanisms of poly(I:C) treatment. Poly(I:C) was i.p. injected 3 h after ischemia (treatment group). Cerebral infarct volumes and brain edemas were significantly reduced, and neurologic scores were significantly increased. TNF-α and IL-1β levels were markedly decreased, whereas IFN-β levels were greatly increased, in the ischemic brain tissues, cerebral spinal fluid, and serum. Injuries to hippocampal neurons and mitochondria were greatly reduced. The numbers of TUNEL-positive and Fluoro-Jade B(+) cells also decreased significantly in the ischemic brain tissues. Poly(I:C) treatment increased the levels of Hsp27, Hsp70, and Bcl2 and decreased the level of Bax in the ischemic brain tissues. Moreover, poly(I:C) treatment attenuated the levels of TNF-α and IL-1β in serum and cerebral spinal fluid of mice stimulated by LPS. However, the protective effects of poly(I:C) against cerebral ischemia were abolished in TLR3(-/-) and TLR4(-/-)mice. Poly(I:C) downregulated TLR4 signaling via TLR3. Poly(I:C) treatment exhibited obvious protective effects 14 d after ischemia and was also effective in the rat permanent middle cerebral artery occlusion model. The results suggest that poly(I:C) exerts therapeutic effects against cerebral I/R injury through the downregulation of TLR4 signaling via TLR3. Poly(I:C) is a promising new drug candidate for the treatment of cerebral infarcts.

Temperature dependence of imprint mechanism in poly(vinylidene fluoride-trifluoroethylene) copolymer ultrathin films

The temperature dependence of imprint in ferroelectric poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) copolymer thin film capacitors has been investigated. The descriptions of imprint versus different temperatures and annealing process are given. It is found that the temperature-induced shift of the imprint rate is limited for all the investigated temperature conditions, and this low shift is mainly associated with the competition between the trap states increasing and detrapping process induced by the temperature rise. Also, the annealing temperature-dependent imprint rates in the polymer chains have been analyzed, and the annealed cell shows low imprint rate after 104 switches at an annealing temperature above 100 °C. Re-annealing recovery process of “inherent” imprint in the ferroelectric thin film capacitor shows improved imprint behaviors, which may be a wake-up of the polarization and detrapping from imprint traps. The internal electric fields for these processes are well analyzed and it is thought that the effective fields as well as charge trap states in ferroelectric layers are strongly responsible for the switching behaviors. This result may be useful for memory device design if extended to cover the temperature dependence of the polarization reversal based on P(VDF-TrFE) copolymer thin film.

Shape memory behavior and mechanism of poly(methyl methacrylate) polymer networks in the presence of star poly(ethylene glycol)

The shape memory poly(methyl methacrylate)/star poly(ethylene glycol) (PMMA/SPEG) networks and poly(methyl methacrylate)/linear poly(ethylene glycol) semi-interpenetrating networks (PMMA/LPEG semi-IPNs) were synthesized. The influence of two structural parameters for two network systems, the crosslinking density of the PMMA network and molecular weight of PEG, on the macroscopic properties of the polymer networks such as thermal properties, mechanical properties, dynamic mechanical properties and shape memory properties has been studied. The results showed that all samples for PMMA/SPEG networks had uniform deformation properties with recovery ratios above 98%. By contrast, PMMA/LPEG semi-IPNs showed poor recovery ratios. For two network systems, whereas the shape recovery speed decreased with increasing crosslinking density and molecular weight of PEG, the shape fixity ratio increased. The shape fixity ratio and shape recovery speed for PMMA/SPEG networks is highly influenced by the two structural parameters of the networks, which have a negligible effect on its shape recovery ratio. It is proven that the embedding of the star-shaped structures greatly improved the shape recovery ratio and recovery speed of the PMMA/SPEG networks with excellent mechanical properties compared to PMMA/LPEG semi-IPNs, which was caused by the star-shaped structures in the PMMA/SPEG networks according to the tube model theory proposed by Edwards and the analysis of the creep properties of the materials.

Abstract B72: Combination therapy by Toll-like receptor 3 activation and chemotherapeutics synergistically induces cancer cell death.

Abstract Toll-like receptors (TLRs) recognize molecular motifs of microbial origin and initiate innate immune response. TLR agonists are already being used in clinical studies because of their ability to induce apoptosis and activate the immune system. We have previously shown that TLR3 activation by synthetic dsRNA [poly (I:C)] in the pharyngeal cancer cell line Detroit 562 induced caspase-dependent apoptosis. Additionally, when combined with chemotherapeutics this treatment acts synergistically by enhancing cancer cell death. In this study we tried to decipher the mechanism of poly (I:C) and chemotherapeutics synergy. Cell survival was determined by using cytotoxicity assay and colony formation assay while protein expression was obtained by western blot. We demonstrated that combination of poly (I:C) and cisplatin is TLR3-dependent while methotrexate and hydroxyurea act through other dsRNA receptors (RIG-I and MDA5). Subsequently, we showed that poly (I:C) had more complex effects on Detroit 562 cells than previously thought: while it induces pro-apoptotic events it also triggers anti-apoptotic mechanisms, for example an increase in the expression of c-IAP2. Combined treatment by poly (I:C) and c-IAP inhibitor significantly decreased cell survival even at low concentrations. However, poly (A:U), which stimulates only TLR3 and not other dsRNA receptors, when combined with c-IAP inhibitor induced cell death only at high concentrations suggesting that RIG-I and MDA5 are also involved. Conversely, the combination of c-IAP inhibitors with poly (I:C) and chemotherapeutics did not result in a stronger cytotoxic effect against malignant cells. One explanation seems to be the fact that cisplatin abrogated c-IAP2 expression induced by poly (I:C) in the Detroit 262 cells thus shifting the balance towards apoptosis. Our conclusion is that future investigations should explore combinations of poly (I:C) with either cisplatin or c-IAP inhibitors. When we used laryngeal cell line SQ20B stably transfected with inducible shRNA for TLR3, we confirmed that synergistic effect of poly (A:U) and cisplatin on cell death is TLR3-dependent. Additionally, as SQ20B is radiation resistant cell line, we have shown here that they can be sensitized to radiotherapy by treatment with poly (I:C). In conclusion, synthetic dsRNAs like poly (I:C) have the potential to help overcoming the resistance of some human malignant cells to classical modalities of radiotherapy and chemotherapy. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):B72. Citation Format: Tanja Matijevic Glavan, Benjamin Verillaud, Pierre Busson, Jasminka Pavelic. Combination therapy by Toll-like receptor 3 activation and chemotherapeutics synergistically induces cancer cell death. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr B72.

Li+ ion conduction mechanism in poly (ε-caprolactone)-based polymer electrolyte

In this work, solid polymer electrolytes based on poly(ɛ-caprolactone) (PCL) with lithium bis(oxalato)borate as a doping salt were prepared by solution cast technique using DMF as a solvent. The electrical DC conductivity and dielectric constant of the solid polymer electrolyte samples were investigated by electrochemical impedance spectroscopy over a frequency range from 50 Hz to 1 MHz. It was found that the DC conductivity increased with increase in the salt concentration to up to 4 wt% and thereafter decreased. Dielectric constant versus salt concentration was used to interpret the decrease in DC conductivity with increase in salt concentration. The DC conductivity as a function of temperature follows Arrhenius behavior in low temperature region, which reveals that ion conduction occurs through successful hopping. The curvature of DC conductivity at high temperatures indicates the contribution of segmental motion to ion conduction. High values for dielectric constant and dielectric loss were observed at low frequencies. The plateau of dielectric constant and dielectric loss at high frequencies can be observed as a result of rapid oscillation of the AC electric field. The HN dielectric function was utilized to study the dielectric relaxation. The experimental and theoretical data of dielectric constant are very close to each other at low temperatures. At high temperatures, the simulated data are more deviated from the experimental curve of dielectric constant due to the dominance of electrode polarization. The non-unity of relaxation parameters (α and β) reveals that the relaxation processes in PCL-based solid electrolyte is a non-Debye type of relaxation.

Emerging treatment options for recurrent ovarian cancer: the potential role of olaparib

Olaparib has shown promising anticancer activity as a single agent in the treatment and maintenance of recurrent ovarian cancer in early clinical trials, but it is far from standard therapy. This article outlines the problem of relapsed ovarian cancer and the mechanisms of poly(ADP-ribose) polymerase inhibitors and reviews the recent literature pertaining to olaparib in ovarian cancer.

Determination of the dye-fixing mechanism of poly(dimethyldiallylammonium chloride)s on cotton fabric

Determination of the dye-fixing mechanism of poly(dimethyldiallylammonium chloride)s on cotton fabric

Doping mechanism in poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate):TiO2 nanoparticles composite films

The doping mechanism for composite poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate) films having TiO2 nanoparticles, denoted TiO2-doped PEDOT:PSS, is investigated in this study. It is shown that TiO2 doping may lead to decreased carrier concentration, owing to a combined effect of the high activation energy and changes in the chemical structure of PEDOT:PSS. The carrier mobility in PEDOT:PSS samples exhibits unexpectedly strong temperature dependence, implying the domination of tunneling (hopping) at low (high) temperatures. An exhibition of high mobility of TiO2-doped PEDOT:PSS samples is attributed to the weak local electron–phonon coupling.

Effect of the regimen of Gaoshan Hongjingtian on the mechanism of poly(ADP-ribose) polymerase regulation of nuclear factor kappa B in the experimental diabetic retinopathy

Background Poly(ADP-ribose) polymerase (PARP) plays an important role in the death of retinal capillary cells in diabetic retinopathy (DR) partly via its regulation of nuclear factor kappa B (NF-κB). The current study investigated the effect of the regimen of Gaoshan Hongjingtian (RG) on the mechanism of PARP regulation of NF-κB, and demonstrated the possible impact of the RG and Gaoshan Hongjingtian (Rhodiola sachalinensis, RS) on diabetic retinopathy. Methods Wistar rats were made diabetic by administering streptozotocin. They were then assigned to three groups at random. After 2 months, the three groups of these diabetic rats were treated with RS or RG, or untreated. Analyses of expression levels of PARP, NF-κB, and intercellular adhesion molecule-1 (ICAM-1) in the retinas of rats in different groups were performed by Western blotting and immunohistochemical assays, and mRNA levels of NF-κB and ICAM-1 were determined by real-time polymerase chain reaction (PCR). In addition, the basement membranes of capillaries in the rats' retinas were observed using electron microscopy, and diabetes-induced capillary degeneration (ghost pericytes and acellular capillaries) were quantitated. Results From the third month after the injection of streptozotocin, the diabetic rats were given daily RG, RS or tap water separately. The diabetic rats failed to gain weight compared with normal age-matched rats, whereas their glycated hemoglobin levels were significantly increased. After 5 months, the mRNA levels of NF-κB and ICAM-1 and the protein expression of PARP, NF-κB, and ICAM-1 were significantly increased in the retinas of diabetic rats in the untreated group compared with the nondiabetic controls. After 8 months, the number of degenerated retinal capillaries (ghost pericytes and acellular capillaries) was significantly increased in the diabetic rats in the untreated group compared with normal age-matched rats. RG and RS inhibited diabetes-induced over-expression of PARP, NF-κB, and ICAM-1 in the retinas of diabetic rats at the end of 5-month diabetic duration. Treatment using RG and RS significantly inhibited increases in the number of acellular capillaries and pericyte ghosts and suppressed the basement membrane thickening in the retinas of rats with diabetes for 8 months compared with the control diabetic rats. Conclusions These results indicate that PARP plays an important role in the pathogenesis of diabetic retinopathy. RS and RG may have acted on the mechanism of PARP regulation of NF-κB, which suppressed the expression of NF-κB and ICAM-1, and led to the inhibition of retinal capillary degeneration.

Mechanism of poly‐l‐lysine‐modified iron oxide nanoparticles uptake into cells

Poly-l-lysine-modified iron oxide nanoparticle (IONP-PLL), which is formed by modifying poly- l-lysine to the surface of iron oxide nanoparticles, can deliver exogenous genes to cells in vitro and in vivo. However, there is relatively little information available about how is IONP-PLL uptaken by cells. In this study, we are focusing on the transferrin receptor (TFR) mediated and TFR-independent cellular internalization of IONP-PLL. The cells were incubated with 1 µM of IONP-PLL with or without transferrin bound. Transferrin-TFR pathway blockers, such as NH4 Cl, CH3 NH2 , or trypsin, were added to the media and their effects were observed. Atomic absorption spectrophotometer was used to quantify the cellular concentration of iron. The cellular concentrations of iron were evaluated at 37°C or 4°C. (1) Transferrin-IONP-PLL uptake into cells was reliant on time and temperature. (2) The addition of blockers, either NH4 CL, CH3 NH2 , or trypsin, decreased the cellular transferrin-dependent IONP-PLL uptake, but not completely blocked the entry of IONP-PLL. (3) When the cells were culture at pH 6.5, under conditions which the binding of iron and transferrin were inhibited, IONP-PLL still had the capacity to enter into cells with time and temperature-dependent manner. These results suggest that the cellular internalization of IONP-PLL, much like iron ion, were mediated by TFR-dependent endocytosis and TFR-free uptake.

Between Superexchange and Hopping: An Intermediate Charge-Transfer Mechanism in Poly(A)-Poly(T) DNA Hairpins

We developed a model for hole migration along relatively short DNA hairpins with fewer that seven adenine (A):thymine (T) base pairs. The model was used to simulate hole migration along poly(A)-poly(T) sequences with a particular emphasis on the impact of partial hole localization on the different rate processes. The simulations, performed within the framework of the stochastic surrogate Hamiltonian approach, give values for the arrival rate in good agreement with experimental data. Theoretical results obtained for hairpins with fewer than three A:T base pairs suggest that hole transfer along short hairpins occurs via superexchange. This mechanism is characterized by the exponential distance dependence of the arrival rate on the donor/acceptor distance, k(a) ≃ e(-βR), with β = 0.9 Å(-1). For longer systems, up to six A:T pairs, the distance dependence follows a power law k(a) ≃ R(-η) with η = 2. Despite this seemingly clear signature of unbiased hopping, our simulations show the complete delocalization of the hole density along the entire hairpin. According to our analysis, the hole transfer along relatively long sequences may proceed through a mechanism which is distinct from both coherent single-step superexchange and incoherent multistep hopping. The criterion for the validity of this mechanism intermediate between superexchange and hopping is proposed. The impact of partial localization on the rate of hole transfer between neighboring A bases was also investigated.

Fabrication and formation mechanism of poly (L-lactic acid) ultrafine multi-porous hollow fiber by electrospinning

Poly(L-lactic acid) (PLLA) ultrafine multi-porous hollow fibers are fabricated by electrospinning with methyl- ene dichloride as solvent. The Kirkendall effect has been widely applied for the fabrication of hollow structure in metals and inorganic materials. In this study, a conceptual extension is proposed for the formation mechanism: the development of porous hollow fiber undergoes three stages. The initial stage is the generation of small voids or pits on the surface of the fiber via surface diffusion and phase separation; the second stage is the formation of multi-pores penetrating the core of the fiber through the interaction of Kirkendall effect, surface diffusion and phase separation; the third stage is dominated by surface diffusion of the core material along the pore surface. To explore the formation conditions, the factors including ambient temperature, relativity humidity (R. H.), molecular weight and fiber diameter are studied. The longitudinal and cross sectional morphologies of these fibers are examined by scanning electron micrograph (SEM). The results show that the prerequisite for the formation of uniform porous hollow PLLA fibers include moderate ambient temperature (10~20°C) and appropriate molecular weight for the PLLA, as well as the diameter of the fiber in the range of several micrometers to about 100 nanometers.

Investigation on the Effects and Mechanisms of PTFE Surface Modification by Low Pressure Plasma

Using argon as the work gas, the effects and mechanisms of poly(tetrafluoroethylene) (PTFE) film surface modification were investigated in a low pressure plasma reactor. Results show that higher hydrophilicity with little degradation, in terms of the scanning electron microscopy (SEM), was obtained after treatment, especially when the sample was placed in the post-discharge area. More polar functional groups and higher surface free energy, especially the polar component, formed on the PTFE surface were responsible for the modification. For the relatively high purity radicals and rare discharge particles in the post-discharge area, the etching was restrained and the introducing reactions were enhanced, and thus, a better modification occurred there.

Charge transport in poly-imidazole membranes: a fresh appraisal of the Grotthuss mechanism

A detailed theoretical investigation of the charge transport mechanism in poly(4-vinyl-imidazole) (P4VI), the parent polymer of a series of N-heterocyclic-based membranes used as an electrolyte in proton exchange membrane fuel cells, is presented. In particular, Density Functional Theory (DFT) results obtained for small model systems (protonated imidazole dimers and trimers) suggest that the commonly accepted conduction mechanism, based on a sequential proton transfer between imidazole moieties, could be impeded by the geometrical constraints imposed by the polymeric backbone. Indeed only one kind of proton transfer reaction is energetically allowed between adjacent imidazoles, so that a rotation of the protonated imidazole is required for a second proton transfer. Molecular dynamics simulations on a larger model (15 oligomers with an excess proton) show that the rotation of the imidazole carrying the excess proton is a soft large amplitude motion. These results allow us to propose a new proton conduction mechanism in P4VI, where a frustrated rotation of the protonated imidazole before each proton transfer reaction represents the rate-limiting step. Furthermore, in contrast with the Grotthuss proton transport mechanism in water, our results indicate that here it is the same proton which could be successively transferred. From a chemical point of view, these new insights into the mechanism are relevant for a rational design of modified azole-based systems for Proton Exchange Membrane Fuel Cells.

Poly I:C inhibits cell proliferation and enhances the growth inhibitory effect of paclitaxel in oral sqaumous cell carcinoma

Objective. Toll-like receptors (TLR) signaling has dual effect of promoting tumor progression and anti-cancer property. This study was designed to determine the effect of polyinosinic-polycytidilic acid (poly I:C), a TLR3 agonist, on the proliferation of oral cancer cells. Materials and methods: Human oral squamous cell carcinoma cell lines, YD-10B and YD-8, were used. TLRs expression was examined by RT-PCR and IL-8 production by poly I:C was examined by ELISA. Cell proliferation was determined by MTT assay. Flow cytometry and Western blot analysis were performed to determine the molecular mechanism of poly I:C-induced cell death. Results. TLR3 was functionally expressed in YD-10B and YD-8 cells. Treatment of poly I:C inhibited the cell growth in a dose-dependent manner. Flow cytometry and Western blot analysis revealed that poly I:C induced apoptosis via a mitochondria-dependent pathway. In addition, combination treatment with poly I:C and paclitaxel more significantly inhibited cell proliferation compared with poly I:C or paclitaxel alone. Conclusions. Poly I:C effectively inhibits oral cancer cell proliferation and can be considered as a candidate to improve the inhibitory effect of anti-cancer drugs.

Studies on Cure Kinetics of Poly(phenylene ether)/Epoxy Resin System Using an Advanced Iso-Conversional Method

The kinetics and mechanism of poly(phenylene ether)/epoxy resin (PPE/EP) cure system were investigated using an advanced iso-convensional method (AICM). The curing experiments of a PPE/EP cure system with different PPE/EP ratios were carried out by means of non-isothermal differential scanning calorimetry (DSC) with different heating rates of 5, 10, 15 and 20°C/min. From the DSC curves, it was shown that the curing mechanism of PPE/EP is very complicated, and PPE content affects most cure kinetic parameters. A variation of the effective activation energy with the extent of conversion was obtained by AICM and analyzed.

Efficient and low potential operative host/guest concentration graded bilayer polymer electrophosphorescence devices

This study investigates enhanced electrophosphorescence and its mechanism in poly(N-vinyl carbazole) (PVK): N,N′-diphenyl-N,N′-bis(3-methylphenyl)-[1,1-biphenyl]-4,4′-diamine (TPD)/2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD): fac-tris(2-phenylpyridine)iridium [Ir(ppy) 3] concentration graded bilayer electroluminescence devices. The two layers are partially intermixed at the bilayer interface because the upper layer (composed of Ir(ppy) 3 and PBD) was spun cast from a solvent that slightly swells the bottom layer (composed of PVK and TPD). Moreover, PBD in the upper layer can act as an efficient electron transport layer as well as a hole blocking layer, resulting in greatly enhanced electron–hole recombination. An indium tin oxide (ITO)/3,4-polyethylenedioxythiophene–polystyrenesulfonate (PEDOT)/[PVK:TPD/Ir(ppy) 3:PBD] bilayer/LiF/Al device showed dramatically decreased turn-on and driving voltages, enhanced luminescence efficiency, and narrower emission spectra compared to those of conventional ITO/PEDOT:PSS/[PVK:TPD:Ir(ppy) 3:PBD] blend/LiF/Al devices.

The mechanism of poly(ethylene glycol) 4000 effect on enzymatic hydrolysis of lignocellulose

Adsorption of cellulase on substrates is a key step for enzymatic hydrolysis of lignocellulose. Addition of surface active additives affects the interaction between cellulase and substrates and has been proven to enhance enzymatic hydrolysis of lignocellulose by many studies. However, the mechanism of poly(ethylene glycol) effect is not yet clear. In this study, enzymatic activity and the adsorption of cellulase on different substrates with different addition sequence of PEG 4000 were investigated. The crystallinity index of substrates incubated by PEG 4000 was also measured by FTIR and XRD. Except for reduction of unproductive binding of cellulase on lignin which was reported by some literatures, current results confirmed a crucial function of PEG 4000 which prevented cellulase deactivation on cellulose rather than lignin through significant difference in adsorption capacity and enzymatic activity of cellulase with different PEG 4000 addition sequence. This conclusion rationally explained PEG 4000 had positive effect on pure cellulose without lignin as well as on lignocellulosic biomass. In addition, PEG 4000 was also found to be contributed to promote the removal of amorphous cellulose. These conclusions are helpful to understand the effect of surface active additives and optimize the enzymatic hydrolysis process.

On the mechanism of poly(methacrylic acid –co– methyl methacrylate)-induced angiogenesis: Gene expression analysis of dTHP-1 cells

Identifying the critical molecules associated with “biocompatibility” is a grand challenge. Poly(methacrylic acid -co- methyl methacrylate) (MAA) beads improve wound closure and wound vascularity in vivo, but the mechanism of this phenomenon is unknown. We used quantitative real-time PCR to identify the subtle changes in the expression of a small selection of molecules involved in wound healing and angiogenesis in a macrophage-like cell (dTHP-1) treated with the MAA beads (45 mol% methacrylic acid). MAA beads decreased the expression of osteopontin (OPN) compared to poly(methyl methacrylate) (PMMA) and untreated cells, and increased the expression of IL-1β, IL-6 and TNF-α over the 24–96 h of the experiment. Interestingly, molecules associated with angiogenesis, such as bFGF, CXCL12, HIF-1α, PDGF-B, TGF-β and VEGF, were not significantly affected by MAA beads over the course of the study. MAA beads also increased the gene expression of OPN in HUVEC compared to untreated cells, while PMMA beads did not. MAA beads modified the phenotype (gene expression) of dTHP-1 cells in a subtle yet distinct manner that was different than PMMA. It remains to connect the changes in OPN in dTHP-1 (and HUVEC) and other molecules to the enhanced vascularity seen in vivo with this polymer.