Iron oxide nanoparticles dispersed within a thermally responsive poly(N-isopropylacrylamide) (PNIPAm) hydrogel matrix effectively convert the photo energy of visible light of modest intensity into thermal energy, providing the efficient means to trigger changes in volumetric swelling of hydrogels. However, long irradiation time (on the order of minutes) and modest volume change limit their applications that need fast response and/or large volume change. In this work, we found that the degree of volume change triggered by light could be maximized by adjusting the lower critical solution temperature (LCST) of the hydrogels. On the basis of the evidence in this investigation, we can develop highly responsive hydrogels that show rapid and significant light-induced volume change, which could be achieved by incorporating a hydrophobic N,N-diethylacrylamide moiety in the PNIPAm network. This enhanced responsiveness led to the successful application of this material in a remote-controllable microvalve for microfluidic devices operated by light illumination within a few seconds.
On-demand release from stimuli-responsive hydrogels has received great attention due to an increasing clinical need. Here, we have prepared spherical hydrogel beads showing visible light-induced volume change at body temper-ature. By spray injection of the monomer solution using the alginate templ-ating method, hybrid beads of several hundred micrometers, consisting of temperature-responsive poly(N-isopropylacrylamide-co-vinyl-2-pyrrolidinone) hydrogel and magnetite nanoparticles (MNP), are produced. MNP dispersed in the hydrogel matrix absorbed visible light and generated heat, increasing the temperature of the matrix and resulting in shrinkage of the beads proportional to light intensity. It is demonstrated that light-induced volume change of dexamethasone-loaded hybrid beads result in on-demand and localized release of the drug by exposure to moderate visible light. As a potential application of the light-sensitive hybrid hydrogel beads, a transdermal patch is developed that incorporates drug-loaded hydrogel beads in multiple drug reservoirs, achieving enhanced release of a model drug when exposed to visible light. This platform should be applicable to on-demand, sequential, and long-term release of drugs via light exposure.
The study examined the clinical utility and psychometric properties of the Korean Modified Checklist of Autism in Toddlers (K-M-CHAT)-2. A sample of 2300 parents of 16- to 36-month-old children was recruited across South Korea. A phone interview was utilized to follow up with participants who initially screened positive for autism spectrum disorder (ASD). Item response theory was applied to assess the psychometric properties of the K-M-CHAT-2. Parents' responses were substantially changed after the follow-up, and the final screen-positive rate was 2.3 %. Results indicated that the psychometric properties of items 1, 3, 11, 18 and 22 were not as strong as the other items. The K-M-CHAT-2 is a useful ASD screening test when implemented with a follow-up.
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