Samson Afewerki

Dr. Samson Afewerki

1. Division of Engineering in Medicine, Department of Medicine, Harvard Medical School, Brigham & Women´s Hospital, Cambridge, MA 02139, USA. 2. Harvard-MIT Division of Health Science and Technology, Massachusetts Institute of Technology, MIT, Cambridge,
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Research Focus & Metrics

Academic Career Length

16Years (2011-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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30 November 2018 in Bioengineering & Translational Medicine
Verified
Journal Article
Open access
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SASamson Afewerki
Samson Afewerki
ASAmir Sheikhi
Amir Sheikhi
SKSoundarapandian Kannan
Soundarapandian Kannan
SASamad Ahadian
Samad Ahadian
Ali  KhademhosseiniAli Khademhosseini
Ali Khademhosseini
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.

11 December 2020 in ACS Nano
Verified
Journal Article
Closed access
SASamson Afewerki
Samson Afewerki
XWXichi Wang
Xichi Wang
GRGuillermo U. Ruiz-Esparza
Guillermo U. Ruiz-Esparza
CTCheuk-Wai Tai
Cheuk-Wai Tai
XKXueying Kong
Xueying Kong
Maria StrømmeMaria Strømme
Maria Strømme

27 September 2018 in ACS Biomaterials Science & Engineering
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Journal Article
Closed access
PKPiotr S. Kowalski
Piotr S. Kowalski
CBChandrabali Bhattacharya
Chandrabali Bhattacharya
SASamson Afewerki
Samson Afewerki
RLRobert Langer
Robert Langer

Verified
Journal Article
Open access
PDF file
AMAlan Ícaro Sousa Morais
Alan Ícaro Sousa Morais
EVEwerton Gomes Vieira
Ewerton Gomes Vieira
SASamson Afewerki
Samson Afewerki
Ricardo de SousaRicardo de Sousa
Ricardo de Sousa
LHLuzia M. C. Honorio
Luzia M. C. Honorio
Anderson de Oliveira LoboAnderson de Oliveira Lobo
Anderson de Oliveira Lobo
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.

6 June 2018 in Biomaterials Science
Verified
Journal Article
Closed access
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Amir SheikhiAmir Sheikhi
Amir Sheikhi
SASamson Afewerki
Samson Afewerki
RORahmi Oklu
Rahmi Oklu
AGAkhilesh K. Gaharwar
Akhilesh K. Gaharwar
Ali  KhademhosseiniAli Khademhosseini
Ali Khademhosseini
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.