Integration of a guided-mode resonance filter with microposts for in-cell protein detection.

We present an integrated microfluidic system consisting of a label-free biosensor of a guided-mode resonance filter (GMRF) and a microfluidic channel with a micropost filter. The GMRF was fabricated through replica molding using an ultraviolet-curable polymer and a plastic substrate. An array of microposts (a diameter and height of 26.5 and 56 µm, respectively, and a spacing between 7.5 and 9.5 µm), fabricated on a silicon substrate through photolithography, was used as the filter. A double-sided tape was used to laminate the GMRF and a microfluidic chip such that the integrated device provides two functions: filtration of the cell debris and quantification of the in-cell protein concentration. By measuring the changes in the resonant wavelength from the GMRF, the detection of ß-actin in an unprocessed lysed cell sample was demonstrated; the cell debris was separated using the micropost filter to prevent false measurement.

A highly efficient bead extraction technique with low bead number for digital microfluidic immunoassay.

Here, we describe a technique to manipulate a low number of beads to achieve high washing efficiency with zero bead loss in the washing process of a digital microfluidic (DMF) immunoassay. Previously, two magnetic bead extraction methods were reported in the DMF platform: (1) single-side electrowetting method and (2) double-side electrowetting method. The first approach could provide high washing efficiency, but it required a large number of beads. The second approach could reduce the required number of beads, but it was inefficient where multiple washes were required. More importantly, bead loss during the washing process was unavoidable in both methods. Here, an improved double-side electrowetting method is proposed for bead extraction by utilizing a series of unequal electrodes. It is shown that, with proper electrode size ratio, only one wash step is required to achieve 98% washing rate without any bead loss at bead number less than 100 in a droplet. It allows using only about 25 magnetic beads in DMF immunoassay to increase the number of captured analytes on each bead effectively. In our human soluble tumor necrosis factor receptor I (sTNF-RI) model immunoassay, the experimental results show that, comparing to our previous results without using the proposed bead extraction technique, the immunoassay with low bead number significantly enhances the fluorescence signal to provide a better limit of detection (3.14 pg/ml) with smaller reagent volumes (200 nl) and shorter analysis time (<1 h). This improved bead extraction technique not only can be used in the DMF immunoassay but also has great potential to be used in any other bead-based DMF systems for different applications.

The agreement of caregivers' initial identification of children's developmental problems with the professional assessment in Taiwan.

Children's developmental problems vary, with some easier to identify than others. The accuracy of caregivers' initial identification of children's developmental problems is important in the timely treatment of those problems by medical professionals. In this study, we investigated the degree to which caregivers' initial identification of children's developmental problems matched the clinical assessment by a team of qualified professionals in a developmental assessment unit of a medical center in Taiwan. The practitioners included a pediatric neurologist, a psychiatrist, a psychologist, an occupational therapist, a physical therapist, and two speech therapists. Caregivers of 943 children (age range: 2-80 months; mean: 37.7 months) who visited the unit for a suspected developmental problem were interviewed about the chief problem that led to the caregivers bringing their children to the unit. The results showed high agreement in the global and the motor domains between the caregivers and the professionals, and low agreement in the cognitive and the speech/language domains. The agreement was significantly related to the caregivers' native origin and socioeconomic status index (SSI). Caregivers with a foreign origin (immigrant mothers) and low SSI were more likely to misidentify their children's problems. It is recommended that pediatric practitioners offer continuing education to caregivers, especially in the domains of cognitive and speech/language development.