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9. Microcantilever arrays functionalised with spiropyran photoactive moieties as systems to measure photo-induced surface stress changes

Author

Química analítica, Kimika analitikoa, Grogan, Catherine, Florea, Larisa, Koprivica, Slavica, Scarmagnani, Silvia, O’Neill, Luke, Lyng, Fiona, Pedreschi, Fran, Benito López, Fernando, Raiteri, Roberto, Química analítica, Kimika analitikoa, Grogan, Catherine, Florea, Larisa, Koprivica, Slavica, Scarmagnani, Silvia, O’Neill, Luke, Lyng, Fiona, Pedreschi, Fran, Benito López, Fernando, and Raiteri, Roberto

Abstract

[EN] Herein we investigate the feasibility of detecting photo-induced surface stress changes using the deflection response of cantilevers. For this purpose, silicon microcantilevers have been functionalised with spiropyran photochromic molecules, using both a monolayer and a polymeric brushes approach. Uponultraviolet light irradiation, the spiropyran unit is converted to the merocyanine form due to the photo-induced cleavage of the Cspiro-O bond. The two forms of the molecule have dramatically different charge,polarity and molecular conformations. This makes spiropyrans an ideal system to study the correlation between photo-induced molecular changes and corresponding changes in surface stress. Our investigations include monitoring the changes in static cantilever deflection, and consequently, surface stress of the spiropyran functionalised cantilevers on exposure to ultraviolet light. Cantilever deflection data reveals that ultraviolet induced conformational changes in the spiropyran moiety cause a change incompressive surface stress and this varies with the type of functionalisation method implemented. The change in surface stress response from the spiropyran polymer brushes functionalised cantilevers gives an average surface stress change of 98 Nm−1(n = 24) while the spiropyran monolayer coated cantilevers have an average surface stress change of about 446 Nm−1(n = 8) upon irradiation with UV light.

Published
2016

10. Microcantilever arrays functionalised with spiropyran photoactive moieties as systems to measure photo-induced surface stress changes

Author

Grogan, Catherine, Florea, Larisa, Koprivica, Slavica, Scarmagnani, Silvia, O’Neill, Luke, Lyng, Fiona, Pedreschi, Fran, Benito-Lopez, Fernando, Raiteri, Roberto, Grogan, Catherine, Florea, Larisa, Koprivica, Slavica, Scarmagnani, Silvia, O’Neill, Luke, Lyng, Fiona, Pedreschi, Fran, Benito-Lopez, Fernando, and Raiteri, Roberto

Abstract

Herein we investigate the feasibility of detecting photo-induced surface stress changes using the deflection response of cantilevers. For this purpose, silicon microcantilevers have been functionalised with spiropyran photochromic molecules, using both a monolayer and a polymeric brushes approach. Upon ultraviolet light irradiation, the spiropyran unit is converted to the merocyanine form due to the photo-induced cleavage of the Cspiro-O bond. The two forms of the molecule have dramatically different charge, polarity and molecular conformations. This makes spiropyrans an ideal system to study the correlation between photo-induced molecular changes and corresponding changes in surface stress. Our investigations include monitoring the changes in static cantilever deflection, and consequently, surface stress of the spiropyran functionalised cantilevers on exposure to ultraviolet light. Cantilever deflection data reveals that ultraviolet induced conformational changes in the spiropyran moiety cause a change in compressive surface stress and this varies with the type of functionalisation method implemented. The change in surface stress response from the spiropyran polymer brushes functionalised cantilevers gives an average surface stress change of 98 Nm-1 (n = 8) while the spiropyran monolayer coated cantilevers have an average surface stress change of about 446 Nm-1 (n = 24) upon irradiation with UV light.

Published
2016

13. Body Composition of Children with Myelomeningocele, Determined by 40K, Urinary Creatinine and Anthropometric Measures

Author

Grogan, Catherine B. and Ekvall, Shirley M.

Abstract

Objective:The purpose of this study was to develop a method to prevent obesity in myelomeningocele (MM) children by determining the effects of growth, calories and physical activity on body composition and to apply this data to clinical practice, specifically, to correlate lean body mass (LBM) with calorie needs and to correlate body fatness with anthropometry measures.Methods:The body compositions of 14 children (four males and ten females) with MM were estimated from potassium content (40K), urinary creatinine and anthropometry measurements at the beginning and end of a six-month period. Three subjects who did not have MM were also evaluated as controls. Dietary and physical activity and dietary-goals estimates were taken from records kept by the patients after initial discussion of physical activity and dietary goals with the families.Results:The study showed potassium content (40K), or LBM, in children with MM to be approximately 50% of the potassium content (40K) of children without MM. The percentage of LBM correlated with physical activity, but not with the location of neurological lesion. Lean body mass and creatinine excretion also were significantly correlated, indicating that creatinine excretion is a good measure of lean body tissue in these children. Thorax and abdominal skinfolds, as well as total circumferential measurements (waist being highest), showed significant correlations with the percent of body fat. The caloric intake requirement to maintain the growth of a child with MM was found to be approximately 50% of the recommended daily allowance (RDA) for a child without MM of the same age. Changes in LBM were observed in children with MM who increased physical activity over a six-month interval and were greater than in those who reduced calories alone, however not significantly, presumably due to the short duration of the study.Conclusion:To prevent obesity, physical activity should begin in infancy; this will increase LBM and thereby calorie needs. Skinfolds and circumferences (abdominal and thorax skinfolds and waist circumference) which significantly correlated with body fat should be used clinically. Calorie needs according to LBM should be reduced to 50% of the RDA or approximately nine cal/cm height for maintenance or seven cal/cm height for weight loss in MM children after age six (possibly at three to four years of age if nonambulatory).

Published
1999
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