ABSTRACT
Self-assembled monolayers of charged polymers are an integral component of many state-of-the-art nanobiosensors. Electrical interactions between charged surfaces and charged biomolecules, adopting the roles of linkers or capture molecules, are not only crucial to the sensor performance but may also be exploited for novel sensing concepts based on electrically actuated interfaces. Here we introduce an analytical model describing the behavior of double-stranded DNA and proteins tethered to externally biased microelectrodes. Continuum electrostatic Poisson-Boltzmann models and the drift-diffusion (Smoluchowski) equation are used to calculate the steady state as well as the dynamic behavior of oligonucleotide rods in DC and AC electric fields. The model predicts the oligonucleotide orientation on the surface and calculates how the increased hydrodynamic drag caused by a protein bound to the DNA's distal end affects the molecular dynamics of the DNA-protein complex. The results of the model are compared to experiments with electrically switchable DNA layers, and very good agreement between theory and experiment is found. The hydrodynamic diameter of the bound protein can be analyzed from experimental data of the slowed motion of the DNA-protein conjugate with angstrom precision.
Subject(s)
DNA/chemistry , Molecular Dynamics Simulation , Proteins/chemistry , DNA/metabolism , Diffusion , Electricity , Entropy , Microelectrodes , Models, Chemical , Proteins/metabolism , Static Electricity , Surface PropertiesABSTRACT
12-month-olds were seen with their mothers and fathers in a laboratory procedure designed to compare infants' solicitation of, emotional resonance to, and self-regulation on the basis of happy, fearful, and conflicting emotional signals from mothers versus fathers. Measures of positive and negative affect and affect lability; of look, approach, and proximity behavior; and of overall response pattern were obtained. Infants showed more positive and less negative affect and greater toy proximity with happy compared to fearful signals. Few differences emerged in infants' referencing response to mothers versus fathers. Infants looked more to mothers than fathers when no signals were given but did not differentiate between parents when only one was signaling or when both were signaling (conflict). In affective state and behavioral regulation, they were not differentially responsive to maternal versus paternal signals either when only one parent was signaling or when both were giving signals.
Subject(s)
Cues , Emotions , Father-Child Relations , Mother-Child Relations , Social Behavior , Arousal , Attention , Female , Humans , Infant , Male , Maternal Behavior , Paternal Behavior , Play and Playthings , Social EnvironmentSubject(s)
Mother-Child Relations , Object Attachment , Female , Humans , Infant, Newborn , Male , Mothers/psychologyABSTRACT
Animal studies on the biological basis of mother-to-infant attachment have led to the hyphothesis that human mother-infant contact shortly after delivery may be crucial for the facilitation of such attachment. However, existing data do not clearly substantiate the influence of early contact on human maternal behavior. The present study was designed with procedural and methodological controls which were not always adequate in earlier studies and tested the hypothesis that early and enhanced contact facilitates maternal attachment behavior. 15 healthy primiparous mothers had their infants 1 hour at delivery and 90 min at each feeding; 15 received the usual hospital routine--brief contact at delivery and 30 min at each feeding. No differences in maternal behavior were obtained on 28 discrete response measures or on pooled sets of individual measures. A modest sex effect between contact conditions was found. Maternal behavior did not differ as a function of age. Factors that may account for differences obtained between this and other studies are discussed.