RESUMEN
Like standard tissue culture plates, tissue engineering scaffolds can be chemically treated to couple proteins without losing the conformation and thus biological function of the proteins; a process called surface functionalization. In this work, the surface of novel 45S5 Bioglass-derived foam-like scaffolds, which exhibit adequate mechanical stability and tailorable bioresorbability, have been modified by applying 3-aminopropyl-triethoxysilane. The efficiency and stability of the surface modification were satisfactorily and quantitatively assessed by X-ray photoemission spectroscopy. It was also found that treatment in buffered (pH 8) water solution at 80 degrees C for 4h, applied during the surface functionalization procedure, accelerated the bioreactive kinetics of the scaffolds, i.e. the transition of the relatively bioinert but mechanically competent crystalline structure of the struts to a biodegradable but mechanically weak amorphous network during immersion in simulated body fluid. Thus the aqueous heat treatment is confirmed to be an important factor that must be considered in the design of these Bioglass-derived glass-ceramic scaffolds. Possible mechanisms responsible for the accelerated bioreactivity are proposed.
Asunto(s)
Materiales Biocompatibles/química , Cerámica/química , Ensayo de Materiales , Silanos/química , Fenómenos Biomecánicos , Líquidos Corporales/química , Tampones (Química) , Simulación por Computador , Cristalización , Microanálisis por Sonda Electrónica , Vidrio , Calor , Concentración de Iones de Hidrógeno , Cinética , Microscopía Electrónica de Rastreo , Modelos Químicos , Porosidad , Propilaminas , Espectrometría por Rayos X , Propiedades de Superficie , Factores de Tiempo , Ingeniería de Tejidos/métodos , Agua/química , Difracción de Rayos XRESUMEN
Instructors and the teaching practices they employ play a critical role in improving student learning in college science, technology, engineering, and mathematics (STEM) courses. Consequently, there is increasing interest in collecting information on the range and frequency of teaching practices at department-wide and institution-wide scales. To help facilitate this process, we present a new classroom observation protocol known as the Classroom Observation Protocol for Undergraduate STEM or COPUS. This protocol allows STEM faculty, after a short 1.5-hour training period, to reliably characterize how faculty and students are spending their time in the classroom. We present the protocol, discuss how it differs from existing classroom observation protocols, and describe the process by which it was developed and validated. We also discuss how the observation data can be used to guide individual and institutional change.