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Biomaterials Mar 2011The complement system is an important regulator of both adaptive and innate immunity, implicating complement as a potential target for immunotherapeutics. We have...
The complement system is an important regulator of both adaptive and innate immunity, implicating complement as a potential target for immunotherapeutics. We have recently presented lymph node-targeting, complement-activating nanoparticles (NPs) as a vaccine platform. Here we explore modulation of surface chemistry as a means to control complement deposition, in active or inactive forms, on polypropylene sulfide core, block copolymer Pluronic corona NPs. We found that nucleophile-containing NP surfaces activated complement and became functionalized in situ with C3 upon serum exposure via the alternative pathway. Carboxylated NPs displayed a higher degree of C3b deposition and retention relative to hydroxylated NPs, upon which deposited C3b was more substantially inactivated to iC3b. This in situ functionalization correlated with in vivo antigen-specific immune responses, including antibody production as well as T cell proliferation and IFN-γ cytokine production upon antigen restimulation. Interestingly, inactivation of C3b to iC3b on the NP surface did not correlate with NP affinity to factor H, a cofactor for protease factor I that degrades C3b into iC3b, indicating that control of complement protein C3 stability depends on architectural details in addition to factor H affinity. These data show that design of NP surface chemistry can be used to control biomaterials-associated complement activation for immunotherapeutic materials.
Topics: Animals; Biocompatible Materials; Complement Activation; Complement C3; Complement Pathway, Alternative; Materials Testing; Mice; Mice, Inbred C57BL; Nanoparticles; Polypropylenes; Sulfides; Surface Plasmon Resonance; Surface Properties; Vaccines
PubMed: 21183216
DOI: 10.1016/j.biomaterials.2010.11.037 -
Journal of Nanoscience and... Aug 2010The rheological properties of nanocomposites consisting of organic modified attapulgite and polypropylene are investigated. The morphology of the nanocomposites was...
The rheological properties of nanocomposites consisting of organic modified attapulgite and polypropylene are investigated. The morphology of the nanocomposites was studied with scanning electron microscopy and X-ray diffraction. Linear dynamic viscoelasticity and steady state flow step of the nanocomposites are presented. For the nanocomposites, the deviation from linear behavior occurs earlier than pure polypropylene at the strain. The storage moduli, loss moduli and dynamic viscosities of the nanocomposites increase monotonically with organoclay concentration. However, the nanocomposites show greater shear thinning tendency than pure polypropylene because of the orientation of the organoclay fibers. Therefore, the nanocomposites have higher moduli but better processibility compared with pure polypropylene.
Topics: Magnesium Compounds; Microscopy, Electron, Scanning; Nanocomposites; Polypropylenes; Rheology; Silicon Compounds; Viscosity; X-Ray Diffraction
PubMed: 21125882
DOI: 10.1166/jnn.2010.2507 -
Molecules (Basel, Switzerland) Nov 2019Achieving sustainability in composite materials for high-performance applications is a key issue in modern processing technologies. In this work, the structure-property...
Achieving sustainability in composite materials for high-performance applications is a key issue in modern processing technologies. In this work, the structure-property relationships of injection molded polypropylene (PP)/biocarbon composites were investigated with a focus on the thermal properties and specific emphasis on the coefficient of linear thermal expansion (CLTE). Biocomposites were produced using 30 wt.% biocarbon in a PP matrix, and two different sources of biocarbon produced at ~650 and 900 °C were used. The overall results were compared with 30 wt.% glass- and talc-filled PP composites. Due to the lamellar morphology of the talc developed during the extrusion-injection molding processing, talc-filled composites showed an increase in the CLTE in the normal direction (ND), and a reduction in the flow direction (FD) with respect to the neat polymer. Glass fiber composites also showed an improvement in the CLTE with respect to the neat polymer. However, the biocarbon-based composites showed the best properties in the ND, with improved values in biocarbon produced at higher temperature. The FD values for both biocarbon composites were improved with respect to the matrix, while biocarbon created at lower temperature showed slightly lower expansion values. A comprehensive explanation of these overall phenomena is supported by a series of morphological, thermal, mechanical and rheological tests.
Topics: Hot Temperature; Polypropylenes; Structure-Activity Relationship
PubMed: 31703289
DOI: 10.3390/molecules24224026 -
Journal of Biomedical Materials... Aug 2018Prostethic mesh material such as nonabsorbable polypropylene used in open and laparoscopic hernia repair are characterized by controllable mechanical properties but may...
Prostethic mesh material such as nonabsorbable polypropylene used in open and laparoscopic hernia repair are characterized by controllable mechanical properties but may elicit undesirable physiological reactions due to the nonphysiological inert polymer material. We succeeded in developing a biocompatible coating for these meshes, based on a physiological inorganic polymer, polyphosphate (polyP) that is morphogenetically active and used as a metabolic energy source, and a collagen matrix. The polyP/collagen hydrogel material was prepared by a freeze-extraction method, with amorphous Ca-polyP microparticles. Electron microscopy (SEM and REM) studies revealed that the polyP/collagen coats are built up of ≈50 nm-sized microparticles deposited onto the collagen matrix which forms a continuous layer around the polypropylene fibers that also spans the mesh pores. This bioresorbable inorganic/organic hybrid coat was found to be degraded during three days of incubation in medium/serum. The biomechanical properties of the coated meshes are comparable to those of the unmodified polypropylene meshes, with a higher toughness in longitudinal orientation and a more pronounced extensibility in the transverse orientation. The polyP/collagen coating improved cell attachment to the polypropylene meshes and strongly increase the growth of fibroblasts (MC3T3-E1 cells). Furthermore, those mats upregulate the expression of the gene encoding the stromal cell-derived factor-1α (SDF-1), a mesenchymal stem cells attracting chemokine in the fibroblasts. We conclude that coating of inert polymer meshes with a biocompatible, collagen-inducing polyP/collagen inorganic/organic hybrid layer may improve tissue integration of the meshes and the outcome of surgical hernia repair and may redudce the foreign body reaction in contaminated field. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2109-2121, 2018.
Topics: Animals; Coated Materials, Biocompatible; Collagen; Herniorrhaphy; Hydrogels; Materials Testing; Mice; NIH 3T3 Cells; Polypropylenes; Surgical Mesh
PubMed: 29024311
DOI: 10.1002/jbm.b.34016 -
Journal of Biomedical Materials Research Nov 1976Extruded filaments of unmodified polypropylene (PP) with and without antioxidant were implanted subcutaneously in hamsters in order to determine their rate of...
Extruded filaments of unmodified polypropylene (PP) with and without antioxidant were implanted subcutaneously in hamsters in order to determine their rate of degradation. Specimens were removed periodically during a 5 month test period and analyzed by infrared spectroscopy and dynamic mechanical testing. The analyses show that degradation beigns to occur after only a few days. Although the reaction sequence is not known, several factors suggest that the in vivo degradation process is similar to autoxidation which occurs in air or oxygen. The infrared data indicate that the hydroxyl content of the implants increases at a rate of 0.061 mg/g polypropylene per day during the initiation phase of the reaction. An induction time of 108 days was extablished. Carbonyl bonds appear after an implantation time of 50--90 days and increase therafter. Mechanical tests indicate a decrease in the dynamic loss tangent, tan delta, during the first month of implantation for unmodified polypropylene. No change in the infrared spectra or tan delta was observed, however, for implants containing an antioxidant. Thus, it is apparent that polypropylene filaments implanted subcutaneously in hamsters degrade by an oxidation process which is retarded effectively by using an antioxidant. While the findings reported are specific to subcutaneous polypropylene implants, they suggest that degradation of other systems may involve similar processes. This notion suggests directions for further research on increasing the in vivo stability of synthetic polymers. Long-term effects of polymer implantation upon tissue were not studied in this work.
Topics: Animals; Antioxidants; Cricetinae; Dermatologic Surgical Procedures; Hydroxylation; Oxidation-Reduction; Plastics; Polypropylenes; Skin; Stress, Mechanical
PubMed: 993229
DOI: 10.1002/jbm.820100611 -
Tissue Engineering. Part A May 2013Hepatocytes in high density are a requisite for the functional performance of complex devices such as bioartificial liver (BAL). In addition to high cell number,...
Hepatocytes in high density are a requisite for the functional performance of complex devices such as bioartificial liver (BAL). In addition to high cell number, efficient mass transfer is also a key parameter in such devices. High-density culture of cells and efficient mass transfer can be achieved in BAL with hollow-fiber-based bioreactors. Even though different types of hollow fibers have been tried in a BAL, prospects of using polypropylene hollow fibers are not well evaluated. In this study, a prototype of bioreactor with polypropylene hollow fibers was fabricated and evaluated for cytotoxicity and hepatocyte function. High density of HepG2/adult hepatocyte cultures was used to evaluate polypropylene hollow fiber to support the biochemical activities (albumin and urea production), ammonia detoxification, and gene expression and to provide effective oxygenation. The results confirmed that a polypropylene hollow-fiber prototype bioreactor is able to provide efficient oxygenation and supported hepatocyte functions in a high-density culture.
Topics: Animals; Bioreactors; Cell Cycle; Cell Survival; Cells, Cultured; Hep G2 Cells; Hepatocytes; Humans; Liver, Artificial; Male; Polypropylenes; Rats; Rats, Wistar
PubMed: 23240809
DOI: 10.1089/ten.TEA.2012.0332 -
Biomedical Chromatography : BMC Jul 2019Stability studies are necessary in healthcare settings as they facilitate fast, cost-effective and efficient work related to batch manufacturing and availability of...
Stability of mycophenolate mofetil in polypropylene 5% dextrose infusion bags and chemical compatibility associated with the use of the Equashield closed-system transfer device.
Stability studies are necessary in healthcare settings as they facilitate fast, cost-effective and efficient work related to batch manufacturing and availability of supplies. We studied the stability of 1-10 mg/mL mycophenolate mofetil (MMF) in polypropylene 5% dextrose infusion bags prepared from Cellcept and with a generic brand name (Micofenolato de Mofetilo Accord) at different storage temperatures. To ensure chemical compatibility during preparation, we also tested MMF sorption to the Equashield closed-system drug transfer device used in this step. For this, a validated stability-indicating high-performance liquid chromatography method was developed for the quantification and identification of MMF in the infusion bags. The analytical selectivity of the assay was determined by subjecting an MMF sample to extreme values of pH, oxidative stress and heat conditions to force degradation. Protected from light, 1-10 mg/mL MMF in infusion polypropylene bags prepared from reconstituted Cellcept 500 mg or Accord 500 mg in 5% dextrose was stable for at least 35 days when stored at 2-8°C or between -15 and -25°C, and for 14 days when stored at 25°C. MMF loss owing to chemical sorption to the Equashield closed-system drug transfer device set was negligible.
Topics: Chromatography, High Pressure Liquid; Drug Delivery Systems; Drug Stability; Glucose; Mycophenolic Acid; Polypropylenes
PubMed: 30845352
DOI: 10.1002/bmc.4529 -
International Journal of Biological... May 2021A novel and environmentally friendly lignin-based surfactant sodium lignosulfonate (SLS) modified layered double hydroxide (LDH) flame retardant (LDH-LS) was fabricated...
A novel and environmentally friendly lignin-based surfactant sodium lignosulfonate (SLS) modified layered double hydroxide (LDH) flame retardant (LDH-LS) was fabricated via co-precipitation method, and subsequently incorporated into polypropylene (PP) matrix to obtain the PP and LDH-LS composites (PP/LDH-LS) by melt blending method. The XRD, FT-IR and XPS results indicated that SLS had successfully modified LDH by adsorbing on the surface of the LDH nanosheet. The WCA and SEM results revealed that the hydrophobic property of LDH-LS had been evidently improved, and it displayed a more homogeneous dispersion than virgin LDH in the PP matrix. Furthermore, cone calorimetry tests (CCT) illustrated that the peak heat release rate (PHRR), total heat release (THR), and total smoke release (TSR) of PP/LDH-LS composites exhibited declines of 62.9%, 25.1%, and 43.3% compared with those of Neat PP, respectively. Besides, the PP/LDH-LS achieved a LOI value of 29.4% and a UL-94 V-0 rating, whereas the PP/LDH showed only a LOI value of 25.2% and a UL-94 V-2 rating at 20 wt% loading. These improvements of flame retardant properties can be attributed to that the well-dispersed LDH-LS and synergistic flame retardancy between LDH and SLS.
Topics: Flame Retardants; Hydroxides; Lignin; Polypropylenes; Smoke; Surface-Active Agents
PubMed: 33631261
DOI: 10.1016/j.ijbiomac.2021.02.148 -
ACS Applied Materials & Interfaces Jul 2015A simple, rapid (10 s) and scalable method to fabricate superhydrophobic polypropylene (PP) fabrics is developed by swelling the fabrics in cyclohexane/heptane mixture...
A simple, rapid (10 s) and scalable method to fabricate superhydrophobic polypropylene (PP) fabrics is developed by swelling the fabrics in cyclohexane/heptane mixture at 80 °C. The recrystallization of the swollen macromolecules on the fiber surface contributes to the formation of submicron protuberances, which increase the surface roughness dramatically and result in superhydrophobic behavior. The superhydrophobic PP fabrics possess excellent repellency to blood, urine, milk, coffee, and other common liquids, and show good durability and robustness, such as remarkable resistances to water penetration, abrasion, acidic/alkaline solution, and boiling water. The excellent comprehensive performance of the superhydrophobic PP fabrics indicates their potential applications as oil/water separation materials, protective garments, diaper pads, or other medical and health supplies. This simple, fast and low cost method operating at a relatively low temperature is superior to other reported techniques for fabricating superhydrophobic PP materials as far as large scale manufacturing is considered. Moreover, the proposed method is applicable for preparing superhydrophobic PP films and sheets as well.
Topics: Cyclohexanes; Hexanes; Hydrophobic and Hydrophilic Interactions; Oils; Polypropylenes; Solvents; Textiles
PubMed: 26061028
DOI: 10.1021/acsami.5b03056 -
Molecules (Basel, Switzerland) May 2019Polypropylene composites reinforced with a filler mixture of graphene nanoplatelet-glass fiber were prepared by melt mixing, while conventional composites containing...
Polypropylene composites reinforced with a filler mixture of graphene nanoplatelet-glass fiber were prepared by melt mixing, while conventional composites containing graphene nanoplatelet and glass fiber were prepared for comparative reasons. An extensive study of thermally stimulated processes such as crystallization, nucleation, and kinetics was carried out using Differential Scanning Calorimetry and Thermogravimetric Analysis. Moreover, effective activation energy and kinetic parameters of the thermal decomposition process were determined by applying Friedman's isoconversional differential method and multivariate non-linear regression method. It was found that the graphene nanoplatelets act positively towards the increase in crystallization rate and nucleation phenomena under isothermal conditions due to their large surface area, inherent nucleation activity, and high filler content. Concerning the thermal degradation kinetics of polypropylene graphene nanoplatelets/glass fibers composites, a change in the decomposition mechanism of the matrix was found due to the presence of graphene nanoplatelets. The effect of graphene nanoplatelets dominates that of the glass fibers, leading to an overall improvement in performance.
Topics: Calorimetry, Differential Scanning; Crystallization; Glass; Graphite; Kinetics; Manufactured Materials; Materials Testing; Polypropylenes; Thermodynamics
PubMed: 31126104
DOI: 10.3390/molecules24101984