University of Madeira

About: University of Madeira is a education organization based out in Funchal, Portugal. It is known for research contribution in the topics: Population & Dendrimer. The organization has 1014 authors who have published 2759 publications receiving 59457 citations.

Bioinspired superhydrophobic poly(L‐lactic acid) surfaces control bone marrow derived cells adhesion and proliferation

Abstract: The aptitude of a cell to adhere, migrate, and differentiate on a compact substrate or scaffold is important in the field of tissue engineering and biomaterials. It is well known that cell behavior can be controlled and guided through the change in micro- and nano-scale topographic features. In this work, we intend to demonstrate that special topographic features that control wettability may also have an important role in the biological performance of biodegradable substrates. Poly(L-lactic acid) surfaces with superhydrophobic characteristics were produced, based on the so-called Lotus effect, exhibiting dual micro- and nano-scale roughness. The water contact angle could be higher than 150° and a value of that order could be kept even upon immersion in a simulated body fluid solution for more than 20 days. Such water repellent surfaces were found to prevent adhesion and proliferation of bone marrow derived cells previously isolated from the femurs of 6-week-old male Wistar rats, when compared with smoother surfaces prepared by simple solvent casting. Such results demonstrate that these superhydrophobic surfaces may be used to control cell behavior onto biodegradable substrates. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009

Surfactants in Mechanical Alloying/Milling: A Catch-22 Situation

Abstract: Mechanical alloying/milling technique is characterized by the repeated welding and fracturing of powder particles in a high-energy ball mill, which often results in excessive cold welding and agglomeration of ductile particles. To achieve the critical balance between cold welding and fracturing, the surface of the deforming particles is modified by introducing a suitable organic material, called surfactant or process control agent (PCA). However, the use of surfactants is self-contradictory by nature and requires further consideration of the milling variables and type/amount of surfactant. The current article provides a practical approach to the promises and challenges associated with surfactants in mechanical alloying/milling. An attempt has been made to address the most crucial aspects correlated with surfactants, including contamination, the morphology and size of powder particles, formation of alloy and microstructural evolution, and powder yield, as well as the physico-mechanical properties, such as ...

Targeted Tumor Computed Tomography Imaging Using Low-Generation Dendrimer-Stabilized Gold Nanoparticles

Abstract: We report a facile approach to fabricating low-generation poly(ami- doamine) (PAMAM) dendrimer-stabi- lized gold nanoparticles (Au DSNPs) functionalized with folic acid (FA) for in vitro and in vivo targeted computed tomography (CT) imaging of cancer cells. In this study, amine-terminated generation 2 PAMAM dendrimers were employed as stabilizers to form Au DSNPs without additional reducing agents. The formed Au DSNPs with an Au core size of 5.5 nm were covalently modified with the targeting ligand FA, followed by acetylation of the remain- ing dendrimer terminal amines to endow the particles with targeting spe- cificity and improved biocompatibility. Our characterization data show that the formed FA-modified Au DSNPs are stable at different pH values (5—8) and temperatures (4-508C), as well as in different aqueous media. MTT assay data along with cell morphology obser- vations reveal that the FA-modified Au DSNPs are noncytotoxic in the particle concentration range of 0-3000 nm .X - ray attenuation coefficient measure- ments show that the CT value of FA- modified Au DSNPs is much higher than that of Omnipaque (a clinically used CT contrast agent) at the same concentration of the radiodense ele- ments (Au or iodine). Importantly, the FA-modified Au DSNPs are able to specifically target a model cancer cell line (KB cells, a human epithelial carci- noma cell line) over-expressing FA re- ceptors and they enable targeted CT imaging of the cancer cells in vitro and the xenografted tumor model in vivo after intravenous administration of the particles. With the simple synthesis ap- proach, easy modification, good cyto- compatibility, and high X-ray attenua- tion coefficient, the FA-modified low- generation Au DSNPs could be used as promising contrast agents for targeted CT imaging of different tumors over- expressing FA receptors.