PHEMA hydrogels modified through the grafting of phosphate groups by ATRP support the attachment and growth of human corneal epithelial cells

Converting the surface of poly(2-hydroxyethyl methacrylate) (PHEMA) hydrogel into a cell-adhesive surface has been successfully achieved through a method based on atom transfer radical polymerization (ATRP) grafting. Following activation of the surface hydroxyl groups of PHEMA by bromination, surface-initiated ATRP of mono(2-methacryloyloxyethyl) phosphate (MMEP) was conducted in a methanol—water system with Cu(I)Br as catalyst at room temperature. The conversion of PHEMA hydroxyl groups to brominated isobutyryl groups and the occurrence of grafting of PMMEP were confirmed by infrared and X-ray photoelectron spectroscopies. Cell attachment experiments were conducted by culturing human corneal limbal epithelial cells on the PMMEP-grafted PHEMA, and on unmodified PHEMA and tissue culture plastic for comparison. The results showed that the grafted PMMEP was homogeneously distributed, and the phosphate groups appeared to significantly promote the attachment, spreading and growth of cells, at a level comparable to the tissue culture plastic

Fathers\u27 and Mothers\u27 Cognitive Stimulation in Early Play with Toddlers: Predictors of 5th grade Reading and Math

Developmental support in early parent-infant interactions has been shown to predict children\u27s early development and later academic success, but the long-term combined impacts of maternal and paternal interactions are rarely examined. For 229 low-income children in the US Early Head Start Research and Evaluation Project, parent-toddler interactions at age 2, observed separately with fathers and mothers, were examined in relation to child outcomes at age 3 and 5th grade. In families with resident biological fathers, both mother and father cognitive stimulation independently predicted 5th grade math and reading, over and above program impacts and child gender. In other families, only mother cognitive stimulation predicted later child outcomes, even if fathers were involved in children\u27s lives. Adding early developmental indicators to the model showed that the contributions of mothers\u27 early cognitive stimulation on children\u27s later academic skills were significantly mediated by children\u27s early development in biological father-resident families, but not in other families. Similarly, adding early developmental indicators to the reading model showed that the contributions of fathers\u27 early cognitive stimulation on children\u27s later reading was partially mediated by children\u27s early vocabulary in biological father-resident families, but not in other families. These results suggest that fathers\u27 and mothers\u27 cognitive stimulation in early play with toddlers both have the potential to make long-term direct and indirect impacts on their children\u27s academic success