CASITA: a controlled pilot study of community-based family coaching to stimulate early child development in Lima, Peru.

OBJECTIVE: To determine whether the 3-month, community-based early stimulation coaching and social support intervention 'CASITA', delivered by community health workers, could improve early child development and caregiver-child interaction in a resource-limited district in Lima, Peru. DESIGN: A controlled two-arm proof-of-concept study. SETTING: Six neighbourhood health posts in Carabayllo, a mixed rural/urban district in Lima. Sessions were held in homes and community centres. PARTICIPANTS: Children aged 6-24 months who screened positive for risk of neurodevelopmental delay (using validated developmental delay tool) and poverty (using progress out of poverty tool) were enrolled with their caregivers. Dyads with children born >21 days early were excluded. INTERVENTION: 12-week parenting/support intervention plus nutritional support (n=41) or nutrition alone (n=19). OUTCOME MEASURES: Development and home environment differences and mean changes from baseline to 3 months postintervention were evaluated using age-adjusted z-scores on the Extended Ages and Stages Questionnaire (EASQ) and the Home Observation Measurement of the Environment (HOME) scores, respectively. RESULTS: Development in CASITA improved significantly in all EASQ domains, whereas the control group's z-scores did not improve significantly in any domain. The mean adjusted difference (MAD) in change in EASQ age-adjusted z-scores between the two study arms was 1.39 (95% CI 0.55 to 2.22); Cohen's d effect size of 0.87 (95% CI 0.23 to 1.50). Likewise, intervention significantly improved global HOME scores versus control group (MAD change of 6.33 (95% CI 2.12 to 10.55); Cohen's d of 0.85 (95% CI 0.28 to 1.41)). CONCLUSIONS: An evidence-based early intervention delivered weekly during 3 months by a community health worker significantly improved children's communication, motor and personal/social development in this proof-of-concept study.

Versatile Particle-Based Route to Engineer Vertically Aligned Silicon Nanowire Arrays and Nanoscale Pores.

Control over particle self-assembly is a prerequisite for the colloidal templating of lithographical etching masks to define nanostructures. This work integrates and combines for the first time bottom-up and top-down approaches, namely, particle self-assembly at liquid-liquid interfaces and metal-assisted chemical etching, to generate vertically aligned silicon nanowire (VA-SiNW) arrays and, alternatively, arrays of nanoscale pores in a silicon wafer. Of particular importance, and in contrast to current techniques, including conventional colloidal lithography, this approach provides excellent control over the nanowire or pore etching site locations and decouples nanowire or pore diameter and spacing. The spacing between pores or nanowires is tuned by adjusting the specific area of the particles at the liquid-liquid interface before deposition. Hence, the process enables fast and low-cost fabrication of ordered nanostructures in silicon and can be easily scaled up. We demonstrate that the fabricated VA-SiNW arrays can be used as in vitro transfection platforms for transfecting human primary cells.

Ultrathin, freestanding, stimuli-responsive, porous membranes from polymer hydrogel-brushes.

The fabrication of freestanding, sub-100 nm-thick, pH-responsive hydrogel membranes with controlled nano-morphology, based on modified poly(hydroxyethyl methacrylate) (PHEMA) is presented. Polymer hydrogel-brush films were first synthesized by surface-initiated atom transfer radical polymerization (SI-ATRP) and subsequently detached from silicon substrates by UV-induced photo-cleavage of a specially designed linker within the initiator groups. The detachment was also assisted by pH-induced osmotic forces generated within the films in the swollen state. The mechanical properties and morphology of the freestanding films were studied by atomic force microscopy (AFM). Inclusion of nanopores of controlled diameter was accomplished by performing SI-ATRP from initiator-coated surfaces that had previously been patterned with polystyrene nanoparticles. Assembly parameters and particle sizes could be varied, in order to fabricate nanoporous hydrogel-brush membranes with tunable pore coverage and characteristics. Additionally, due to the presence of weak polyacid functions within the hydrogel, the membranes exhibited pH-dependent thickness in water and reversible opening/closing of the pores.

A multiscale approach to the adsorption of core-shell nanoparticles at fluid interfaces.

Self-assembly of colloidal particles at liquid-liquid interfaces is a process with great potential for the creation of controlled structures, due to the trapping of the particles in the plane of the interface combined with their lateral mobility. Here we present a multiscale characterisation of the adsorption and interfacial behaviour of core-shell iron oxide-poly(ethylene glycol) nanoparticles at a water-n-decane interface using three complementary, in situ, methods, which span many different length scales. First, dynamic interfacial measurements are taken to follow the adsorption of particles from the bulk aqueous phase to the interface. The mechanical properties of the interface are then probed using micron-sized tracers in probe-particle tracking and nano-tracers in fluorescence correlation spectroscopy. The results show that the rate of particle adsorption to the interface scales with the square of bulk concentration, as predicted by a recent model. In addition, we show that despite full monolayers of nanoparticles forming, the interface remains unexpectedly fluid, with only a slowing of tracer particle mobility but no evidence of interface jamming as seen for hard nanoparticles. Our results illustrate that nanoparticles stabilised by soft, extended polymeric shells, display distinct features at fluid interfaces that can be harnessed for the fabrication of functional materials.