21 research outputs found
Tissue engineered vascular grafts are resistant to the formation of dystrophic calcification
Get PDFAdvancements in congenital heart surgery have heightened the importance of durable biomaterials for adult survivors. Dystrophic calcification poses a significant risk to the long-term viability of prosthetic biomaterials in these procedures. Herein, we describe the natural history of calcification in the most frequently used vascular conduits, expanded polytetrafluoroethylene grafts. Through a retrospective clinical study and an ovine model, we compare the degree of calcification between tissue-engineered vascular grafts and polytetrafluoroethylene grafts. Results indicate superior durability in tissue-engineered vascular grafts, displaying reduced late-term calcification in both clinical studies (p¿<¿0.001) and animal models (p¿<¿0.0001). Further assessments of graft compliance reveal that tissue-engineered vascular grafts maintain greater compliance (p¿<¿0.0001) and distensibility (p¿<¿0.001) than polytetrafluoroethylene grafts. These properties improve graft hemodynamic performance, as validated through computational fluid dynamics simulations. We demonstrate the promise of tissue engineered vascular grafts, remaining compliant and distensible while resisting long-term calcification, to enhance the long-term success of congenital heart surgeries.Peer ReviewedArticle signat per 19 autors/es: Mackenzie E. Turner, Kevin M. Blum, Tatsuya Watanabe, Erica L. Schwarz, Mahboubeh Nabavinia, Joseph T. Leland, Delaney J. Villarreal, William E. Schwartzman, Ting-Heng Chou, Peter B. Baker, Goki Matsumura, Rajesh Krishnamurthy, Andrew R. Yates, Kan N. Hor, Jay D. Humphrey, Alison L. Marsden, Mitchel R. Stacy, Toshiharu Shinoka & Christopher K. BreuerPostprint (published version
Synthesis and evaluation of catalytic application of porous resin
Get PDFThe abilities to tailor catalytic functional groups and chemical characteristics onto a robust polymer structure make mesoporous phenolic resins great candidates for catalytic support applications. The use of a template synthesis method for configuring a catalytic structure is neither commercially nor environmentally friendly. In this Ph.D. thesis, new one-pot template-free methods for synthesizing mesoporous metal-doped phenol-formaldehyderesin were developed. The methods facilitate scaling for industrial catalytic applications in pharmaceutical, environmental, and medical applications. Heterogeneous palladium centered catalytic mesoporous structures were synthesized by a single-stage template-free method. BET adsorption measurements, SEM, EDX, XPS, and TEM were used to study the surface area, uniformity of Pd distribution, and an interconnected porous network structure. Subsequently, the activity of the catalyst was evaluated in bed batch and continuous reactors for Suzuki-Miyaura cross-coupling reactions. The catalyst was confirmed for biocompatibility and used for extracellular synthesis of anti-cancer PP121 drug in the mono-cell layer and 3D printed model structures with encapsulated cells. The metabolic activity and flow cytometry results confirmed the efficiency of this catalyst for in-situ drug synthesis. Additionally, this catalyst was doped using cobalt and nickel and evaluated for CO2 capture and electrochemical conversion to fuels and chemicals
Evaluation of adsorption efficiency of activated carbon/chitosan composite for removal of Cr (VI) and Cd (II) from single and bi-solute dilute solution
No full textThe aim of this study was to evaluate the adsorption capacity of the novel coated activated carbon by chitosan for removal of Cr (VI) and Cd (II) ions from single and bi-solute dilute aqueous solutions. In addition, the adsorption abilities of activated carbon (AC), chitosan (CH) and chitosan / activated carbon composite (CHAC) have been compared. Adsorption studies were performed in a batch system, and the effects of various operating parameters such as solution pH, particle size and the dose of adsorbent were considered for removal of Cr (VI) and Cd (II) by Taguchi method. Equilibrium experimental data were well fitted to Langmuir isotherm for single and bi-solute solutions. The adsorption capacities of AC and CH adsorbents have improved by synthesis CHAC composite. As it was expected, competitive adsorption of metal ions on the CHAC surface led to reducing the adsorption capacity from 90.9 mg g-1 to 41.94 mg g-1 for Cr (VI) and 52.63 mg g-1 to 30.21 mg g-1 for Cd (II) ions, respectively. The adsorption capacities for the metal solution–adsorbent systems are in the order Cr (VI) > Cd (II). The kinetic studies indicated that the adsorption process was best described by the pseudo-second-order kinetics for single and bi-solute solutions
Developing Eco-Friendly and Cost-Effective Porous Adsorbent for Carbon Dioxide Capture.
Get PDFTo address the issue of global warming and climate change issues, recent research efforts have highlighted opportunities for capturing and electrochemically converting carbon dioxide (CO2). Despite metal doped polymers receiving widespread attention in this respect, the structures hitherto reported lack in ease of synthesis with scale up feasibility. In this study, a series of mesoporous metal-doped polymers (MRFs) with tunable metal functionality and hierarchical porosity were successfully synthesized using a one-step copolymerization of resorcinol and formaldehyde with Polyethyleneimine (PEI) under solvothermal conditions. The effect of PEI and metal doping concentrations were observed on physical properties and adsorption results. The results confirmed the role of PEI on the mesoporosity of the polymer networks and high surface area in addition to enhanced CO2 capture capacity. The resulting Cobalt doped material shows excellent thermal stability and promising CO2 capture performance, with equilibrium adsorption of 2.3 mmol CO2/g at 0C and 1 bar for at a surface area 675.62 m2/g. This mesoporous polymer, with its ease of synthesis is a promising candidate for promising for CO2 capture and possible subsequent electrochemical conversion
Cloning and Optimization of Formate Dehydrogenase Gene Expression in E. COLI
No full textIntroduction: The increase in greenhouse gas levels and the gradual warming of the earth have garnered worldwide interest. The enzyme formate-dehydrogenase can reduce CO2 by converting it into formate, which is subsequently converted into methanol by the enzyme alcohol dehydrogenase. The purpose of this research was to evaluate the effect of different concentrations of IPGT, modifier, induction time and culture medium on the expression of formate-dehydrogenase enzyme and optimization.
Methods: Specific primers were designed to amplify the gene fragment using polymerase chain reaction (PCR). The Formate-dehydrogenase enzyme gene was inserted into the pET28b vector, and the recombinant plasmid was used to transform E.coli. To enhance protein expression, a Taguchi experimental design was conducted to investigate the effects of temperature, inducer concentration, and type of culture medium type on protein expression levels at two different levels.
Results: PCR results confirmed the amplification of formate-dehydrogenase enzyme gene in E. coli DH5α. Induction time and concentration negatively impacted on expression. The highest level of expression of the recombinant protein was observed 24 hours post-induction at a temperature of 25°C, with an IPTG concentration of 0.1 mM in the presence of sorbitol. LB culture medium was chosen as the best expression medium.
Conclusion: This study showed that low concentrations of IPTG were sufficient for producing the recombinant protein, proving to be economical. Reducing the induction time also increased protein expression. LB medium enhanced with sorbitol was identified to be the best culture medium for inducing the expression of the formate dehydrogenase enzyme
Enhanced mechanical properties and biocompatibility of novel hydroxyapatite/TOPAS hybrid composite for bone tissue engineering applications
No full textHydrogel-Encapsulated Heterogenous Mesoporous Resin Catalyst for In Situ Anti-Cancer Agent Production under Biological Conditions.
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Hydrogel-Encapsulated Heterogenous Mesoporous Resin Catalyst for In Situ Anti-Cancer Agent Production under Biological Conditions
Get PDFA heterogenous Palladium anchored Resorcinol-formaldehyde-hyperbranched PEI mesoporous catalyst, made by one-pot synthesis, was used successfully for in situ Suzuki-Miyaura cross coupling synthesis of anticancer prodrug PP-121 from iodoprazole and boronic ester precursors. The mesoporous catalyst with the non-cytotoxic precursors were tested in 2D in vitro model with excellent cytocompatibility and a strong suppression of PC3 cancer cell proliferation, underscored by 50% reduction in PC3 cells viability and 55% reduction in cell metabolism activity and an enhanced rate of early and late apoptosis in flow cytometry, that was induced only by successful in situ pro drug PP121 synthesis from the precursors. The 3D gelatin methacrylate hydrogel encapsulated in vitro cell models underscored the results with a 52% reduction in cell metabolism and underscored apoptosis of PC3 cells when the Pd anchored catalyst was combined with the precursors. In situ application of Suzuki-Miyaura cross coupling of non-cytotoxic precursors to cancer drug, along with their successful encapsulation in an injectable hydrogel could be applied for tumor point drug delivery strategies that can circumvent deleterious side effects and poor bioavailability chemotherapy routes with concomitant enhanced efficacy
3D Bioprinting: Patient-Specific Bioinks for 3D Bioprinting of Tissue Engineering Scaffolds (Adv. Healthcare Mater. 11/2018)
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