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ABSTRACT:Silanization has emerged in recent years as a way to obtain a stronger and more stable attachment of biomolecules to metallic substrates. However, its impact on protein conformation, a key aspect that influences cell response, has hardly been studied. In this work we analyzed by AFM the distribution and conformation of type I collagen on plasma treated surfaces before and after silanization. Subsequently, we investigated the effect of the different collagen conformations on fibroblasts adhesion and fibronectin secretion by immunofluorescence analyses. Two different organosilanes were used on plasma-treated titanium surfaces, either 3-chloropropyl-triethoxy-silane (CPTES), or 3-Glycidyloxypropyl-triethoxy-silane (GPTES). The properties and amount of the adsorbed collagen was assessed by contact angle, XPS, OWLS and AFM.AFM studies revealed different conformations of type I collagen depending on the silane employed. Collagen was organized in fibrillar networks over very hydrophilic (plasma treated titanium) or hydrophobic (silanized with CPTES) surfaces, the latter forming little globules with a beads-on-a-string appearance, whereas over surfaces presenting an intermediate hydrophobic character (silanized with GPTES), collagen was organized into clusters with a size increasing at higher protein concentration in solution.Cell response was strongly affected by collagen conformation, especially at low collagen density. The samples exhibiting collagen organized in globular clusters (GPTES-functionalized samples) favored a faster and better fibroblast adhesion, as well as better cell spreading, focal adhesions formation and more pronounced fibronectin fibrillogenesis. In contrast, when a certain protein concentration was reached at the material surface the effect of collagen conformation was masked, and similar fibroblast response was observed in all samples.

In this work, different bioactive compounds were obtained from Calendula officinalis by using conventional soxhlet extraction, shaker-assisted extraction and ultrasound-assisted extraction. The effect of different extraction time and temperature on the quantity of bioactive compounds obtained was investigated. The extracts obtained were further analyzed by UV–visible spectrometric analysis. The effect of extraction technique on both the colorant power of carotenoids and antibacterial capacity of the flavonoids was evaluate. Colorant power was evaluated by UV–visible spectrometric and dyeing ability in dairy product. Antibacterial activity of extracts was developed against Escherichia coli and Salmonella typhimurium by diffusion technique in well. Outstanding extraction results were obtained by ultrasound extraction technique performed during 2 hours, at 30°C and with 96% ethanol, for bioactive compounds evaluated. The same treatment showed the best result in colorant power and dyeing ability. The extracts obtained by ultrasound had a slightly inhibitory effect of growth on E. coli in comparison with the other techniques, while none of the extracts obtained from the different techniques reported a significant inhibition on the growth of S. Typhi. Therefore, ultrasound-assisted extraction is considered as an alternative process for obtaining the bioactive compounds from C. officinalis with high concentration, colorant power and antibacterial activity.