Publications by authors named "Samson Afewerki"

31 Publications

Nanostructured Non-Newtonian Drug Delivery Barrier Prevents Postoperative Intrapericardial Adhesions.

ACS Appl Mater Interfaces 2021 Jun 17;13(25):29231-29246. Epub 2021 Jun 17.

Division of Engineering in Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, United States.

With the increasing volume of cardiovascular surgeries and the rising adoption rate of new methodologies that serve as a bridge to cardiac transplantation and that require multiple surgical interventions, the formation of postoperative intrapericardial adhesions has become a challenging problem that limits future surgical procedures, causes serious complications, and increases medical costs. To prevent this pathology, we developed a nanotechnology-based self-healing drug delivery hydrogel barrier composed of silicate nanodisks and polyethylene glycol with the ability to coat the epicardial surface of the heart without friction and locally deliver dexamethasone, an anti-inflammatory drug. After the fabrication of the hydrogel, mechanical characterization and responses to shear, strain, and recovery were analyzed, confirming its shear-thinning and self-healing properties. This behavior allowed its facile injection (5.75 ± 0.15 to 22.01 ± 0.95 N) and subsequent mechanical recovery. The encapsulation of dexamethasone within the hydrogel system was confirmed by H NMR, and controlled release for 5 days was observed. , limited cellular adhesion to the hydrogel surface was achieved, and its anti-inflammatory properties were confirmed, as downregulation of ICAM-1 and VCAM-1 was observed in TNF-α activated endothelial cells. , 1 week after administration of the hydrogel to a rabbit model of intrapericardial injury, superior efficacy was observed when compared to a commercial adhesion barrier, as histological and immunohistochemical examination revealed reduced adhesion formation and minimal immune infiltration of CD3+ lymphocytes and CD68+ macrophages, as well as NF-κβ downregulation. We presented a novel nanostructured drug delivery hydrogel system with unique mechanical and biological properties that act synergistically to prevent cellular infiltration while providing local immunomodulation to protect the intrapericardial space after a surgical intervention.
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http://dx.doi.org/10.1021/acsami.0c20084DOI Listing
June 2021

Oxygen-generating microparticles in chondrocytes-laden hydrogels by facile and versatile click chemistry strategy.

Colloids Surf B Biointerfaces 2021 Sep 13;205:111850. Epub 2021 May 13.

LIMAV-Interdisciplinary Laboratory for Advanced Materials, BioMatLab, UFPI - Federal University of Piaui, Teresina, PI, 64049-550, Brazil; Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139, United States. Electronic address:

Currently, oxygen supply for in vitro cell culture is one of the major challenges in tissue engineering, especially in three-dimensional (3D) structures, such as polymeric hydrogels, because oxygen is an essential element for cells survival. In this context, oxygen levels must be maintained in articular cartilage to promote the differentiation, viability, and proliferation of chondrocytes due to the low level of oxygen presence in this region. Although some technologies employ oxygen-generating materials to add sufficient oxygen levels, the limitations and challenges of current technologies include the lack of controlled, sustained, and prolonged release of the oxygen. Moreover, the fabrication methods may leave some impurities or residues resulting in toxicity to the cells. "Click" chemistry is a facile, versatile, and compatible chemical strategy to engineer hydrogels for tissue engineering applications. Herein, we disclose the engineering of oxygen-generating microparticles in chondrocytes-laden hydrogels through a versatile catalyst-free tetrazine and norbornene inverse electron demand Diels‒Alder (iEDDA) click reaction. The hydrogels combine chondroitin sulfate (CS) and poly(ethylene glycol) (PEG) crosslinked in situ, displaying tunable rheological and mechanical properties, for sustained and prolonged oxygen-release. Gene expression analysis of the chondrocytes by real-time reverse transcription polymerase chain reaction (RT-PCR) demonstrated promising cell response within the engineered hydrogel.
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http://dx.doi.org/10.1016/j.colsurfb.2021.111850DOI Listing
September 2021

Engineering multifunctional bactericidal nanofibers for abdominal hernia repair.

Commun Biol 2021 02 19;4(1):233. Epub 2021 Feb 19.

Division of Engineering in Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.

The engineering of multifunctional surgical bactericidal nanofibers with inherent suitable mechanical and biological properties, through facile and cheap fabrication technology, is a great challenge. Moreover, hernia, which is when organ is pushed through an opening in the muscle or adjacent tissue due to damage of tissue structure or function, is a dire clinical challenge that currently needs surgery for recovery. Nevertheless, post-surgical hernia complications, like infection, fibrosis, tissue adhesions, scaffold rejection, inflammation, and recurrence still remain important clinical problems. Herein, through an integrated electrospinning, plasma treatment and direct surface modification strategy, multifunctional bactericidal nanofibers were engineered showing optimal properties for hernia repair. The nanofibers displayed good bactericidal activity, low inflammatory response, good biodegradation, as well as optimal collagen-, stress fiber- and blood vessel formation and associated tissue ingrowth in vivo. The disclosed engineering strategy serves as a prominent platform for the design of other multifunctional materials for various biomedical challenges.
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http://dx.doi.org/10.1038/s42003-021-01758-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7896057PMC
February 2021

Biomineralization inspired engineering of nanobiomaterials promoting bone repair.

Mater Sci Eng C Mater Biol Appl 2021 Jan 4;120:111776. Epub 2020 Dec 4.

LIMAV-Interdisciplinary Laboratory for Advanced Materials, Materials Science and Engineering Graduate Program, UFPI - Federal University of Piaui, Teresina, PI 64049-550, Brazil. Electronic address:

A biomineralization processes is disclosed for engineering nanomaterials that support bone repair. The material was fabricated through a hot press process using electrospun poly(lactic acid) (PLA) matrix covered with hybrid composites of carbon nanotubes/graphene nanoribbons (GNR) and nanohydroxyapatite (nHA). Various scaffolds were devised [nHA/PLA, PLA/GNR, and PLA/nHA/GNR (1 and 3%)] and their structure and morphology characterized through Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDS), and Atomic force microscope (AFM). Moreover, thorough biocompatibility and toxicity studies were performed. Here, in vivo studies on toxicity and cytotoxicity were conducted in aqueous dispersions of the biomaterials at concentrations of 30, 60, and 120 μg/mL using the Allium cepa test. Further toxicity studies were performed through hemolysis toxicity tests and genotoxicity tests evaluating the damage index and damage frequencies of DNAs through comet assays with samples of the animals' peripheral blood, marrow, and liver. Additionally, the regenerative activity of the scaffolds was analyzed by measuring the cortical tibiae of rats oophorectomized implanted with the biomaterials. Biochemical analyzes [glutamic pyruvic transaminase (GPT), glutamic oxaloacetic transaminase (GOT), urea, calcium, phosphorus, and alkaline phosphatase (ALP)] were also performed on blood samples. The results suggested a toxicity and cytotoxicity level for the GNR biomaterials at a concentration of 60 and 120 μg/mL, but non-toxicity and cytotoxicity for the 30 μg/mL concentration. The scaffolds obtained at a concentration of 0.3 mg/cm were not toxic in the hemolysis test and demonstrated no cytotoxicity, genotoxicity, and mutagenicity in the blood, marrow, and liver analyzes of the animals, corroborating data from the biochemical markers of GPT, GOT, and urea. Tissue regeneration was performed in all groups and was more pronounced in the group containing the combination of nHA/GNR (3%), which is consistent with the data obtained for the calcium, serum phosphorus, and ALP concentrations. Consequently, the study indicates that the engineered nanobiomaterial is a promising candidate for bone tissue repair and regenerative applications. STATEMENT OF SIGNIFICANCE: The scientific contribution of this study is the engineering of a synthetic hybrid biomaterial, in nanoscale by a pressing and heating process. A biodegradable polymeric matrix was covered on both sides with a carbonated hybrid bioceramic/graphene nanoribbons (GNR), which has hydrophilic characteristics, with chemical elements stoichiometrically similar to bone mineral composition. The nanomaterial displayed promising bone regeneration ability, which is the first example to be used in an osteoporotic animal model. Moreover, detailed biocompatibility and toxicity studies were performed on the nanomaterials and their compositions, which is of great interest for the scientific community.
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http://dx.doi.org/10.1016/j.msec.2020.111776DOI Listing
January 2021

Combined Catalysis for Engineering Bioinspired, Lignin-Based, Long-Lasting, Adhesive, Self-Mending, Antimicrobial Hydrogels.

ACS Nano 2020 Dec 11. Epub 2020 Dec 11.

Division of Nanotechnology and Functional Materials, Department of Materials Science and Engineering, Ångström Laboratory, Uppsala University, Box 35, 751 03 Uppsala, Sweden.

The engineering of multifunctional biomaterials using a facile sustainable methodology that follows the principles of green chemistry is still largely unexplored but would be very beneficial to the world. Here, the employment of catalytic reactions in combination with biomass-derived starting materials in the design of biomaterials would promote the development of eco-friendly technologies and sustainable materials. Herein, we disclose the combination of two catalytic cycles (combined catalysis) comprising oxidative decarboxylation and quinone-catechol redox catalysis for engineering lignin-based multifunctional antimicrobial hydrogels. The bioinspired design mimics the catechol chemistry employed by marine mussels in nature. The resultant multifunctional sustainable hydrogels (1) are robust and elastic, (2) have strong antimicrobial activity, (3) are adhesive to skin tissue and various other surfaces, and (4) are able to self-mend. A systematic characterization was carried out to fully elucidate and understand the facile and efficient catalytic strategy and the subsequent multifunctional materials. Electron paramagnetic resonance analysis confirmed the long-lasting quinone-catechol redox environment within the hydrogel system. Initial biocompatibility studies demonstrated the low toxicity of the hydrogels. This proof-of-concept strategy could be developed into an important technological platform for the eco-friendly, bioinspired design of other multifunctional hydrogels and their use in various biomedical and flexible electronic applications.
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http://dx.doi.org/10.1021/acsnano.0c06346DOI Listing
December 2020

Phyco-remediation of swine wastewater as a sustainable model based on circular economy.

J Environ Manage 2021 Jan 28;278(Pt 2):111534. Epub 2020 Oct 28.

Tecnologico de Monterrey, School of Engineering and Sciences, Monterrey, 64849, Mexico. Electronic address:

Pork production has expanded in the world in recent years. This growth has caused a significant increase in waste from this industry, especially of wastewater. Although there has been an increase in wastewater treatment, there is a lack of useful technologies for the treatment of wastewater from the pork industry. Swine farms generate high amounts of organic pollution, with large amounts of nitrogen and phosphorus with final destination into water bodies. Sadly, little attention has been devoted to animal wastes, which are currently treated in simple systems, such as stabilization ponds or just discharged to the environment without previous treatment. This uncontrolled release of swine wastewater is a major cause of eutrophication processes. Among the possible treatments, phyco-remediation seems to be a sustainable and environmentally friendly option of removing compounds from wastewater such as nitrogen, phosphorus, and some metal ions. Several studies have demonstrated the feasibility of treating swine wastewater using different microalgae species. Nevertheless, the practicability of applying this procedure at pilot-scale has not been explored before as an integrated process. This work presents an overview of the technological applications of microalgae for the treatment of wastewater from swine farms and the by-products (pigments, polysaccharides, lipids, proteins) and services of commercial interest (biodiesel, biohydrogen, bioelectricity, biogas) generated during this process. Furthermore, the environmental benefits while applying microalgae technologies are discussed.
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http://dx.doi.org/10.1016/j.jenvman.2020.111534DOI Listing
January 2021

Oxygen-generating smart hydrogels supporting chondrocytes survival in oxygen-free environments.

Colloids Surf B Biointerfaces 2020 Oct 13;194:111192. Epub 2020 Jun 13.

LIMAV - Interdisciplinary Laboratory for Advanced Materials, BioMatLab, UFPI - Federal University of Piauí, Teresina, PI, 64049-550, Brazil. Electronic address:

Cartilage is one of our body's tissues which are not repaired automatically by itself. Problems associated with cartilage are very common worldwide and are considered the leading cause of pain and disability. Smart biomaterial or "Four dimensional" (4D) biomaterials has started emerging as a suitable candidate, which are principally three dimensional (3D) materials that change their morphology or generate a response measured at space and time to physiologic stimuli. In this context, the release of oxygen through hydrogels in contact with water is considered as 4D biomaterials. The objective of this study is to develop strategies to release oxygen in a sustainable and prolonged manner through hydrogels systems to promote chondrocytes survival in oxygen-free environment. The 4D biomaterials are engineered from gelatin methacryloyl (GelMA) loaded with calcium peroxide (CPO), which have the ability to generate oxygen in a controlled and sustained manner for up to 6 days. The incorporation of CPO into the hydrogel system provided materials with enhanced mechanical and porosity properties. Furthermore, the hydrogels promoted chondrocyte survival and reduced cell death under oxygen-free conditions.
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http://dx.doi.org/10.1016/j.colsurfb.2020.111192DOI Listing
October 2020

Sustainable and recyclable heterogenous palladium catalysts from rice husk-derived biosilicates for Suzuki-Miyaura cross-couplings, aerobic oxidations and stereoselective cascade carbocyclizations.

Sci Rep 2020 04 14;10(1):6407. Epub 2020 Apr 14.

Department of Natural Sciences, Mid Sweden University, Sundsvall, SE-85170, Sweden.

A new eco-friendly approach for the preparation of sustainable heterogeneous palladium catalysts from rice husk-derived biogenic silica (RH-Si and RH-Si). The designed heterogeneously supported palladium species (RH-Si-NH-Pd and RH-Si-NH-Pd) were fully characterized and successfully employed as catalysts for various chemical transformations (C-C bond-forming reactions, aerobic oxidations and carbocyclizations). Suzuki-Miyaura transformations were highly efficient in a green solvent system (HO:EtOH (1:1) with excellent recyclability, providing the cross-coupling products with a wide range of functionalities in high isolated yields (up to 99%). Palladium species (Pd(0)-nanoparticles or Pd(II)) were also efficient catalysts in the green aerobic oxidation of an allylic alcohol and a co-catalytic stereoselective cascade carbocyclization transformation. In the latter case, a quaternary stereocenter was formed with excellent stereoselectivity (up to 27:1 dr).
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http://dx.doi.org/10.1038/s41598-020-63083-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7156381PMC
April 2020

Electrospraying Oxygen-Generating Microparticles for Tissue Engineering Applications.

Int J Nanomedicine 2020 19;15:1173-1186. Epub 2020 Feb 19.

LIMAV-Interdisciplinary Laboratory for Advanced Materials, Materials Science and Engineering Graduate Program, UFPI-Federal University of Piauí, Teresina, PI CEP 64049-550, Brazil.

Background: The facile preparation of oxygen-generating microparticles (M) consisting of Polycaprolactone (PCL), Pluronic F-127, and calcium peroxide (CPO) (PCL-F-CPO-M) fabricated through an electrospraying process is disclosed. The biological study confirmed the positive impact from the oxygen-generating microparticles on the cell growth with high viability. The presented technology could work as a prominent tool for various tissue engineering and biomedical applications.

Methods: The oxygen-generated microparticles fabricated through electrospraying processes were thoroughly characterization through various methods such as X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) analysis, and scanning electron microscopy (SEM)/SEM-Energy Dispersive Spectroscopy (EDS) analysis.

Results: The analyses confirmed the presence of the various components and the porous structure of the microparticles. Spherical shape with spongy characteristic microparticles were obtained with negative charge surface (ζ = -16.9) and a size of 17.00 ± 0.34 μm. Furthermore, the biological study performed on rat chondrocytes demonstrated good cell viability and the positive impact of increasing the amount of CPO in the PCL-F-CPO-M.

Conclusion: This technological platform could work as an important tool for tissue engineering due to the ability of the microparticles to release oxygen in a sustained manner for up to 7 days with high cell viability.
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http://dx.doi.org/10.2147/IJN.S237334DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7037066PMC
June 2020

Printing 3D Hydrogel Structures Employing Low-Cost Stereolithography Technology.

J Funct Biomater 2020 Feb 22;11(1). Epub 2020 Feb 22.

LIMAV - Interdisciplinary Laboratory for Advanced Materials, BioMatLab, Materials Science and Engineering Graduate Program, UFPI - Federal University of Piauí, Teresina 64049-550, Brazil.

Stereolithography technology associated with the employment of photocrosslinkable, biocompatible, and bioactive hydrogels have been widely used. This method enables 3D microfabrication from images created by computer programs and allows researchers to design various complex models for tissue engineering applications. This study presents a simple and fast home-made stereolithography system developed to print layer-by-layer structures. Polyethylene glycol diacrylate (PEGDA) and gelatin methacryloyl (GelMA) hydrogels were employed as the photocrosslinkable polymers in various concentrations. Three-dimensional (3D) constructions were obtained by using the stereolithography technique assembled from a commercial projector, which emphasizes the low cost and efficiency of the technique. Lithium phenyl-2,4,6-trimethylbenzoyl phosphonate (LAP) was used as a photoinitiator, and a 404 nm laser source was used to promote the crosslinking. Three-dimensional and vascularized structures with more than 5 layers and resolutions between 42 and 83 µm were printed. The 3D printed complex structures highlight the potential of this low-cost stereolithography technique as a great tool in tissue engineering studies, as an alternative to bioprint miniaturized models, simulate vital and pathological functions, and even for analyzing the actions of drugs in the human body.
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http://dx.doi.org/10.3390/jfb11010012DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7151634PMC
February 2020

Fabrication of Polymeric Microparticles by Electrospray: The Impact of Experimental Parameters.

J Funct Biomater 2020 Jan 15;11(1). Epub 2020 Jan 15.

LIMAV-Interdisciplinary Advanced Materials Laboratory, PPGCM-Materials Science and Engineering Graduate Program, UFPI-Federal University of Piaui, Teresina 64049-550, Brazil.

Microparticles (MPs) with controlled morphologies and sizes have been investigated by several researchers due to their importance in pharmaceutical, ceramic, cosmetic, and food industries to just name a few. In particular, the electrospray (ES) technique has been shown to be a viable alternative for the development of single particles with different dimensions, multiple layers, and varied morphologies. In order to adjust these properties, it is necessary to optimize different experimental parameters, such as polymer solvent, voltage, flow rate (FR), type of collectors, and distance between the collector and needle tip, which will all be highlighted in this review. Moreover, the influence and contributions of each of these parameters on the design and fabrication of polymeric MPs are described. In addition, the most common configurations of ES systems for this purpose are discussed, for instance, the main configuration of an ES system with monoaxial, coaxial, triaxial, and multi-capillary delivery. Finally, the main types of collectors employed, types of synthesized MPs and their applications specifically in the pharmaceutical and biomedical fields will be emphasized. To date, ES is a promising and versatile technology with numerous excellent applications in the pharmaceutical and biomaterials field and such MPs generated should be employed for the improved treatment of cancer, healing of bone, and other persistent medical problems.
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http://dx.doi.org/10.3390/jfb11010004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7151563PMC
January 2020

Advances in dual functional antimicrobial and osteoinductive biomaterials for orthopaedic applications.

Nanomedicine 2020 02 18;24:102143. Epub 2019 Dec 18.

LIMAV - Interdisciplinary Laboratory for Advanced Materials, Department of Materials Engineering, UFPI- Federal University of Piauí, Teresina, PI, Brazil; Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA. Electronic address:

A vast growing problem in orthopaedic medicine is the increase of clinical cases with antibiotic resistant pathogenic microbes, which is predicted to cause higher mortality than all cancers combined by 2050. Bone infectious diseases limit the healing ability of tissues and increase the risk of future injuries due to pathologic tissue remodelling. The traditional treatment for bone infections has several drawbacks and limitations, such as lengthy antibiotic treatment, extensive surgical interventions, and removal of orthopaedic implants and/or prosthesis, all of these resulting in long-term rehabilitation. This is a huge burden to the public health system resulting in increased healthcare costs. Current technologies e.g. co-delivery systems, where antibacterial and osteoinductive agents are delivered encounter challenges such as site-specific delivery, sustained and prolonged release, and biocompatibility. In this review, these aspects are highlighted to promote the invention of the next generation biomaterials to prevent and/or treat bone infections and promote tissue regeneration.
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http://dx.doi.org/10.1016/j.nano.2019.102143DOI Listing
February 2020

Enamine/Transition Metal Combined Catalysis: Catalytic Transformations Involving Organometallic Electrophilic Intermediates.

Top Curr Chem (Cham) 2019 Nov 16;377(6):38. Epub 2019 Nov 16.

Department of Natural Sciences, Mid Sweden University, 851 70, Sundsvall, Sweden.

The concept of merging enamine activation catalysis with transition metal catalysis is an important strategy, which allows for selective chemical transformations not accessible without this combination. The amine catalyst activates the carbonyl compounds through the formation of a reactive nucleophilic enamine intermediate and, in parallel, the transition metal activates a wide range of functionalities such as allylic substrates through the formation of reactive electrophilic π-allyl-metal complex. Since the first report of this strategy in 2006, considerable effort has been devoted to the successful advancement of this technology. In this chapter, these findings are highlighted and discussed.
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http://dx.doi.org/10.1007/s41061-019-0267-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6858407PMC
November 2019

Dual effective core-shell electrospun scaffolds: Promoting osteoblast maturation and reducing bacteria activity.

Mater Sci Eng C Mater Biol Appl 2019 Oct 21;103:109778. Epub 2019 May 21.

Department of Physics and Materials Science and Engineering graduate program, Federal University of Piaui, 64049-550 Teresina, PI, Brazil. Electronic address:

Herein, we electrospun ultrathin core-shell fibers based on polycaprolactone (PCL), polyethylene glycol (PEG), gelatin and osteogenic growth peptide (OGP), and evaluated their potential to upregulate human osteoblast cells (hFOB) and to reduce Gram-positive and Gram-negative bacteria. We also evaluated the fiber morphology, chemical structure and peptide delivery efficacy. The employment of core-shell fibers compared to fibers without a core-shell showed improved mechanical strength, comparable to the strength of pure PCL, as well as improved hydrophilicity and wettability. The careful selection of polymer combination and core-shell strategy promoted a controlled and sustained release of OGP. Moreover, increased calcium deposition (CD) (1.3-fold) and alkaline phosphate (ALP) activity was observed when hFOBs were cultivated onto core-shell fibers loaded with OGP after 21 days of culture. Our developed scaffolds were also able to reduce the amount of Pseudomonas aeruginosa (ATCC 25668) bacteria by a factor of two compared to raw PCL without the use of any antibiotics. All of these results demonstrate a promising potential of the developed core-shell electrospun scaffolds based on PCL:PEG:Gelatin:OGP for numerous bone tissue applications.
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http://dx.doi.org/10.1016/j.msec.2019.109778DOI Listing
October 2019

Combination of nejayote and swine wastewater as a medium for Arthrospira maxima and Chlorella vulgaris production and wastewater treatment.

Sci Total Environ 2019 Aug 23;676:356-367. Epub 2019 Apr 23.

Tecnologico de Monterrey, School of Engineering and Sciences, Campus Monterrey, Ave. Eugenio Garza Sada 2501, CP 64849 Monterrey, N.L., Mexico. Electronic address:

Nejayote and swine wastewater are highly pollutant effluents and a source of organic matter load that sometimes released into water bodies (rivers or lakes), soils or public sewer system, with or without partial treatments. Nejayote is a wastewater product of alkaline cooking of maize, whereas, swine wastewater results from the primary production of pigs for the meat market. Owing to the presence of environmentally related pollutants, both sources are considered the major cause of pollution and thus require urgent action. Herein, we report a synergistic approach to effectively use and/or treat Nejayote and swine wastewater as a cost-effective culture medium for microalgae growth, which ultimately induces the removal of polluting agents. In this study, the strains Arthrospira maxima and Chlorella vulgaris were grown using different dilutions of Nejayote and swine wastewater. Both wastewaters were used as the only source of macronutrients and trace elements for growth. For A. maxima, the treatment of 10% nejayote and 90% of water (T3) resulted in a cell growth of 32 × 10 cell/mL at 12 days (μ = 0.27/d). While, a mixture of 25% swine wastewater, 25% nejayote and 50% water (T2) produced 32 × 10 cell/mL at 18 days (μ = 0.16/d). A significant reduction was also noted as 92% from 138 mg/L of TN, 75% from 77 mg/L of TP, and 96% from 8903 mg/L of COD, among different treatments. For C. vulgaris, the treatment of 10% swine wastewater and 90% water (T1) gave a cell growth of 128 × 10 cell/mL (μ = 0.57/d) followed by T3 yielded 62 × 10 cell/mL (μ = 0.70/d) and T2 yielded 48 × 10 cell/mL (μ = 0.54/d). Up to 91% reduction from 138 mg/L of TN, 85% from 19 mg/L of TP and 96% from 4870 mg/L of COD was also recorded. These results show that microalgae can be used to treat these types of wastewater while at the same time using them as a culture media for microalgae. The resultant biomass can additionally be used for getting other sub-products of commercial interest.
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http://dx.doi.org/10.1016/j.scitotenv.2019.04.278DOI Listing
August 2019

Bioprinting a Synthetic Smectic Clay for Orthopedic Applications.

Adv Healthc Mater 2019 07 8;8(13):e1900158. Epub 2019 Apr 8.

LIMAV Interdisciplinary Laboratory for Advanced Materials, Department of Materials Engineering, UFPI-Federal University of Piauí, Teresina, PI, 64049-550, Brazil.

Bioprinting technology has emerged as an important approach to bone and cartilage tissue engineering applications, because it allows the printing of scaffolds loaded with various components, such as cells, growth factors, or drugs. In this context, the bone has a very complex architecture containing highly vascularized and calcified tissues, while cartilage is avascular and has low cellularity and few nutrients. Owing to this complexity, the repair and regeneration of these tissues are highly challenging. Identification of the appropriate biomaterial and fabrication technologies can provide sustainable solutions to this challenge. Here, nanosized Laponite (Laponite is a trademark of the company BYK Additives Ltd.) has shown to be a promising material due to its unique properties such as excellent biocompatibility, facile gel formation, shear-thinning property (reversible physical crosslinking), high specific surface area, degrade into nontoxic products, and with osteoinductive properties. Even though Laponite and Laponite-based composite for 3D bioprinting application are considered as soft gels, they may therefore not be thought exhibiting sufficient mechanical strength for orthopedic applications. However, through the merging with suitable composite and, also by incorporation of crosslinking step, desired mechanical strength for orthopedic application can be obtained. In this review, recent advances and future perspective of bioprinting Laponite and Laponite composites for orthopedic applications are highlighted.
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http://dx.doi.org/10.1002/adhm.201900158DOI Listing
July 2019

The Chemical Synthesis and Applications of Tropane Alkaloids.

Alkaloids Chem Biol 2019;81:151-233. Epub 2018 Sep 7.

Department of Natural Sciences, Mid Sweden University, Sundsvall, Sweden; Berzelii Center EXSELENT, The Arrhenius Laboratory, Stockholm University, Stockholm, Sweden. Electronic address:

Tropanes are an important class of alkaloid natural products that are found in plants all over the world. These compounds can exhibit significant biological activity and are among the oldest known medicines. In the early 19th century, tropanes were isolated, characterized, and synthesized by notable chemical researchers. Their significant biological activities have inspired tremendous research efforts toward their synthesis and the elucidation of their pharmacological activity both in academia and in industry. In this chapter, which addresses the developments in this field since 1994, the focus is on the synthesis of these compounds, and several examples of sophisticated synthetic protocols involving both asymmetric and catalytic approaches are described. In addition, the structures of more than 100 new alkaloids are included as well as the applications and pharmacological properties of some tropane alkaloids.
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http://dx.doi.org/10.1016/bs.alkal.2018.06.001DOI Listing
April 2019

Gelatin-polysaccharide composite scaffolds for 3D cell culture and tissue engineering: Towards natural therapeutics.

Bioeng Transl Med 2019 Jan 28;4(1):96-115. Epub 2018 Dec 28.

Biomaterials Innovation Research Center, Division of Biomedical Engineering, Dept. of Medicine Brigham and Women's Hospital, Harvard Medical School Cambridge MA 02142.

Gelatin is a promising material as scaffold with therapeutic and regenerative characteristics due to its chemical similarities to the extracellular matrix (ECM) in the native tissues, biocompatibility, biodegradability, low antigenicity, cost-effectiveness, abundance, and accessible functional groups that allow facile chemical modifications with other biomaterials or biomolecules. Despite the advantages of gelatin, poor mechanical properties, sensitivity to enzymatic degradation, high viscosity, and reduced solubility in concentrated aqueous media have limited its applications and encouraged the development of gelatin-based composite hydrogels. The drawbacks of gelatin may be surmounted by synergistically combining it with a wide range of polysaccharides. The addition of polysaccharides to gelatin is advantageous in mimicking the ECM, which largely contains proteoglycans or glycoproteins. Moreover, gelatin-polysaccharide biomaterials benefit from mechanical resilience, high stability, low thermal expansion, improved hydrophilicity, biocompatibility, antimicrobial and anti-inflammatory properties, and wound healing potential. Here, we discuss how combining gelatin and polysaccharides provides a promising approach for developing superior therapeutic biomaterials. We review gelatin-polysaccharides scaffolds and their applications in cell culture and tissue engineering, providing an outlook for the future of this family of biomaterials as advanced natural therapeutics.
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http://dx.doi.org/10.1002/btm2.10124DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6336672PMC
January 2019

Understanding the impact of crosslinked PCL/PEG/GelMA electrospun nanofibers on bactericidal activity.

PLoS One 2018 20;13(12):e0209386. Epub 2018 Dec 20.

Faculty of Medical Sciences, State University of Campinas, Campinas, São Paulo, Brazil.

Herein, we report the design of electrospun ultrathin fibers based on the combination of three different polymers polycaprolactone (PCL), polyethylene glycol (PEG), and gelatin methacryloyl (GelMA), and their potential bactericidal activity against three different bacteria Staphylococcus aureus (S. aureus), Pseudomonas aeruginosa (P. aeruginosa), and Methicillin-resistant Staphylococcus aureus (MRSA). We evaluated the morphology, chemical structure and wettability before and after UV photocrosslinking of the produced scaffolds. Results showed that the developed scaffolds presented hydrophilic properties after PEG and GelMA incorporation. Moreover, they were able to significantly reduce gram-positive, negative, and MRSA bacteria mainly after UV photocrosslinking (PCL:PEG:GelMa-UV). Furthermore, we performed a series of study for gaining a better mechanistic understanding of the scaffolds bactericidal activity through protein adsorption study and analysis of the reactive oxygen species (ROS) levels. Furthermore, the in vivo subcutaneous implantation performed in rats confirmed the biocompatibility of our designed scaffolds.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0209386PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6301679PMC
May 2019

Electrospun nanofiber blend with improved mechanical and biological performance.

Int J Nanomedicine 2018 22;13:7891-7903. Epub 2018 Nov 22.

Division of Engineering in Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Cambridge, MA 02139, USA,

Background: Here, electrospun fibers based on a blend of polycaprolactone (PCL), poly(ethylene glycol) (PEG), and gelatin methacryloyl (GelMA) were developed. The careful choice of this polymer combination allowed for the preparation of a biomaterial that preserved the mechanical strength of PCL, while at the same time improving the hydrophilicity of the blended material and human osteoblast maturation.

Methods: The morphology, chemical structure, wettability, and mechanical properties before and after UV photocrosslinking were evaluated. Furthermore, human osteoblasts (hFOB) were cultivated for up to 21 days on the scaffolds, and their potential to upregulate cell proliferation, alkaline phosphatase (ALP) activity, and calcium deposition were investigated.

Results: Contact angle measurement results showed that the developed scaffolds presented hydrophilic properties after PEG and GelMA incorporation before (25°) and after UV photocross-linking (69°) compared to pure PCL (149°). PCL:PEG:GelMA-UV displayed a slight increase in mechanical strength (elastic modulus ~37 MPa) over PCL alone (~33 MPa). Normally, an increase in strength of fibers leads to a decrease in elongation at break, due to the material becoming less deformable and stiffer, thus leading to breaks at low strain. This behavior was observed by comparing PCL (elongation at break ~106%) and PCL:PEG:GelMA-UV (~50%). Moreover, increases in ALP activity (10-fold at day 14) and calcium deposition (1.3-fold at day 21) by hFOBs were detected after PEG and GelMA incorporation after UV photocross-linking compared to pure PCL. Ultrathin and hydrophilic fibers were obtained after PEG and GelMA incorporation after UV photocrosslinking, but the strength of PCL was maintained. Interestingly, those ultrathin fiber characteristics improved hFOB functions.

Conclusion: These findings appear promising for the use of these electrospun scaffolds, based on the combination of polymers used here for numerous orthopedic applications.
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http://dx.doi.org/10.2147/IJN.S175619DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6255114PMC
January 2019

Smart Biomaterials: Recent Advances and Future Directions.

ACS Biomater Sci Eng 2018 Nov 15;4(11):3809-3817. Epub 2018 Oct 15.

Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, United States.

Smart biomaterials have the ability to respond to changes in physiological parameters and exogenous stimuli and continue to impact many aspects of modern medicine. Smart materials can promote promising therapies and improve treatment of debilitating diseases. Here, we describe recent advances in the current state-of-the-art design and application of smart biomaterials in tissue engineering, drug delivery systems, medical devices, and immune engineering.
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http://dx.doi.org/10.1021/acsbiomaterials.8b00889DOI Listing
November 2018

Prolonged Drug-Releasing Fibers Attenuate Alzheimer's Disease-like Pathogenesis.

ACS Appl Mater Interfaces 2018 Oct 22;10(43):36693-36702. Epub 2018 Oct 22.

Institute of Science and Technology , Universidade Brasil , Itaquera 08230-030 , São Paulo , Brazil.

Delivering drugs and agents to the brain is a huge challenge, especially for chronic neurodegenerative disorders, such as Alzheimer's disease (AD). For this, prolonged and sustained release methods to increase brain uptake represent an impacting concept. The bioresorbable polymer poly-lactic acid (PLA) has high potential for medical implants; at the same time, glucagon-like peptide-1 (GLP-1) analogues have considerable neuroprotective attributes and represent a therapeutic strategy for AD. Here, a biodevice is produced by electrospinning PLA with a GLP-1 analogue (liraglutide, LG), coated with a thin layer of gelatin. The biodevice is subcutaneously implanted in a transgenic mouse model of AD and LG is released for 14 days in mice serum. After 4 weeks of implantation, crucial hallmarks of the AD are highly diminished: hippocampal senile amyloid β plaque load and neuroinflammatory markers. Furthermore, neurogenesis is enhanced in the subventricular zone, an important neurogenic niche in the brain. The designed biodevice holds great promise for being an affordable candidate to act as a prolonged drug provider, promoting LG mission through increasing its lifetime, constituting a relevant approach for old and impaired brain.
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http://dx.doi.org/10.1021/acsami.8b12649DOI Listing
October 2018

Effect of ionic strength on shear-thinning nanoclay-polymer composite hydrogels.

Biomater Sci 2018 Jul;6(8):2073-2083

Biomaterials Innovation Research Center, Division of Biomedical Engineering, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Cambridge, MA 02139, USA.

Nanoclay-polymer shear-thinning composites are designed for a broad range of biomedical applications, including tissue engineering, drug delivery, and additive biomanufacturing. Despite the advances in clay-polymer injectable nanocomposites, colloidal properties of layered silicates are not fully considered in evaluating the in vitro performance of shear-thinning biomaterials (STBs). Here, as a model system, we investigate the effect of ions on the rheological properties and injectability of nanoclay-gelatin hydrogels to understand their behavior when prepared in physiological media. In particular, we study the effect of sodium chloride (NaCl) and calcium chloride (CaCl2), common salts in phosphate buffered saline (PBS) and cell culture media (e.g., Dulbecco's Modified Eagle's Medium, DMEM), on the structural organization of nanoclay (LAPONITE® XLG-XR, a hydrous lithium magnesium sodium silicate)-polymer composites, responsible for the shear-thinning properties and injectability of STBs. We show that the formation of nanoclay-polymer aggregates due to the ion-induced shrinkage of the diffuse double layer and eventually the liquid-solid phase separation decrease the resistance of STB against elastic deformation, decreasing the yield stress. Accordingly, the stress corresponding to the onset of structural breakdown (yield zone) is regulated by the ion type and concentration. These results are independent of the STB composition and can directly be translated into the physiological conditions. The exfoliated nanoclay undergoes visually undetectable aggregation upon mixing with gelatin in physiological media, resulting in heterogeneous hydrogels that phase separate under stress. This work provides fundamental insights into nanoclay-polymer interactions in physiological environments, paving the way for designing clay-based injectable biomaterials.
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http://dx.doi.org/10.1039/c8bm00469bDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6085890PMC
July 2018

Sustainable Design for the Direct Fabrication and Highly Versatile Functionalization of Nanocelluloses.

Glob Chall 2017 Oct 13;1(7):1700045. Epub 2017 Sep 13.

Department of Natural Sciences Mid Sweden University Holmgatan 10 851 70 Sundsvall Sweden.

This study describes a novel sustainable concept for the scalable direct fabrication and functionalization of nanocellulose from wood pulp with reduced energy consumption. A central concept is the use of metal-free small organic molecules as mediators and catalysts for the production and subsequent versatile surface engineering of the cellulosic nanomaterials via organocatalysis and click chemistry. Here, "organoclick" chemistry enables the selective functionalization of nanocelluloses with different organic molecules as well as the binding of palladium ions or nanoparticles. The nanocellulosic material is also shown to function as a sustainable support for heterogeneous catalysis in modern organic synthesis (e.g., Suzuki cross-coupling transformations in water). The reported strategy not only addresses obstacles and challenges for the future utilization of nanocellulose (e.g., low moisture resistance, the need for green chemistry, and energy-intensive production) but also enables new applications for nanocellulosic materials in different areas.
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http://dx.doi.org/10.1002/gch2.201700045DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6607377PMC
October 2017

Combinations of Aminocatalysts and Metal Catalysts: A Powerful Cooperative Approach in Selective Organic Synthesis.

Chem Rev 2016 11 10;116(22):13512-13570. Epub 2016 Oct 10.

Department of Natural Sciences, Mid Sweden University , SE-851 70 Sundsvall, Sweden.

The cooperation and interplay between organic and metal catalyst systems is of utmost importance in nature and chemical synthesis. Here innovative and selective cooperative catalyst systems can be designed by combining two catalysts that complement rather than inhibit one another. This refined strategy can permit chemical transformations unmanageable by either of the catalysts alone. This review summarizes innovations and developments in selective organic synthesis that have used cooperative dual catalysis by combining simple aminocatalysts with metal catalysts. Considerable efforts have been devoted to this fruitful field. This emerging area employs the different activation modes of amine and metal catalysts as a platform to address challenging reactions. Here, aminocatalysis (e.g., enamine activation catalysis, iminium activation catalysis, single occupied molecular orbital (SOMO) activation catalysis, and photoredox activation catalysis) is employed to activate unreactive carbonyl substrates. The transition metal catalyst complements by activating a variety of substrates through a range of interactions (e.g., electrophilic π-allyl complex formation, Lewis acid activation, allenylidene complex formation, photoredox activation, C-H activation, etc.), and thereby novel concepts within catalysis are created. The inclusion of heterogeneous catalysis strategies allows for "green" chemistry development, catalyst recyclability, and the more eco-friendly synthesis of valuable compounds.
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http://dx.doi.org/10.1021/acs.chemrev.6b00226DOI Listing
November 2016

Combined heterogeneous metal/chiral amine: multiple relay catalysis for versatile eco-friendly synthesis.

Angew Chem Int Ed Engl 2014 Mar;53(13):3447-51

Herein is described a versatile and broad synergistic strategy for expansion of chemical space and the synthesis of valuable molecules (e.g. carbocycles and heterocycles), with up to three quaternary stereocenters, in a highly enantioselective fashion from simple alcohols (31 examples, 95:5 to >99.5:0.5 e.r.) using integrated heterogeneous metal/chiral amine multiple relay catalysis and air/O₂ as the terminal oxidant. A novel highly 1,4-selective heterogeneous metal/amine co-catalyzed hydrogenation of enals was also added to the relay catalysis sequences.
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http://dx.doi.org/10.1002/anie.201310216DOI Listing
March 2014

A palladium/chiral amine co-catalyzed enantioselective dynamic cascade reaction: synthesis of polysubstituted carbocycles with a quaternary carbon stereocenter.

Angew Chem Int Ed Engl 2013 Jun 25;52(23):6050-4. Epub 2013 Apr 25.

Department of Natural Sciences, Engineering and Mathematics, Mid Sweden University, 85170 Sundsvall, Sweden.

Polysubstituted 5- and 6-membered carbocycles were synthesized by the title reaction. The one-pot dynamic relay process generates four new stereocenters, including a quaternary carbon center, in a highly enantioselective fashion (99.5:0.5→99:0.5 e.r.) by using a simple combination of palladium and chiral amine co-catalysts.
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http://dx.doi.org/10.1002/anie.201300559DOI Listing
June 2013

Palladium/chiral amine co-catalyzed enantioselective β-arylation of α,β-unsaturated aldehydes.

Angew Chem Int Ed Engl 2013 Jan 23;52(3):878-82. Epub 2012 Nov 23.

Department of Natural Sciences, Engineering and Mathematics, Mid Sweden University, 85170 Sundsvall, Sweden.

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http://dx.doi.org/10.1002/anie.201208634DOI Listing
January 2013

Highly enantioselective cascade transformations by merging heterogeneous transition metal catalysis with asymmetric aminocatalysis.

Sci Rep 2012 14;2:851. Epub 2012 Nov 14.

Department of Organic Chemistry, The Arrhenius Laboratory, Stockholm University, Stockholm, Sweden.

The concept of combining heterogeneous transition metal and amine catalysis for enantioselective cascade reactions has not yet been realized. This is of great advantage since it would allow for the recycling of expensive and non-environmentally friendly transition metals. We disclose that the use of a heterogeneous Pd-catalyst in combination with a simple chiral amine co-catalyst allows for highly enantioselective cascade transformations. The preparative power of this process has been demonstrated in the context of asymmetric cascade Michael/carbocyclization transformations that delivers cyclopentenes bearing an all carbon quaternary stereocenters in high yields with up to 30:1 dr and 99% ee. Moreover, a variety of highly enantioselective cascade hetero-Michael/carbocyclizations were developed for the one-pot synthesis of valuable dihydrofurans and pyrrolidines (up to 98% ee) by using bench-stable heterogeneous Pd and chiral amines as co-catalysts.
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http://dx.doi.org/10.1038/srep00851DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3496984PMC
April 2013

Direct regiospecific and highly enantioselective intermolecular α-allylic alkylation of aldehydes by a combination of transition-metal and chiral amine catalysts.

Chemistry 2012 Mar 1;18(10):2972-7. Epub 2012 Feb 1.

Department of Natural Sciences, Engineering and Mathematics, Mid Sweden University, 851 70 Sundsvall, Sweden.

The first direct intermolecular regiospecific and highly enantioselective α-allylic alkylation of linear aldehydes by a combination of achiral bench-stable Pd(0) complexes and simple chiral amines as co-catalysts is disclosed. The co-catalytic asymmetric chemoselective and regiospecific α-allylic alkylation reaction is linked in tandem with in situ reduction to give the corresponding 2-alkyl alcohols with high enantiomeric ratios (up to 98:2 e.r.; e.r.=enantiomeric ratio). It is also an expeditious entry to valuable 2-alkyl substituted hemiacetals, 2-alkyl-butane-1,4-diols, and amines. The concise co-catalytic asymmetric total syntheses of biologically active natural products (e.g., Arundic acid) are disclosed.
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http://dx.doi.org/10.1002/chem.201103366DOI Listing
March 2012
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