Objective Interpretation of the Rapid Urease Test for Helicobacter pylori Infection Using Colorimetry.

BACKGROUND: The rapid urease test (RUT) is a major diagnostic tool for detecting Helicobacter pylori infection. This study aimed to establish an objective method for measuring the color changes in the RUT kit to improve the test's diagnostic accuracy. METHODS: A UV-visible spectrophotometer was selected as the colorimeter; experiments were conducted in three stages to objectively identify the color changes in the RUT kit. RESULTS: First, the urea broth solution showed an identifiable color change from yellow to red as the pH increased by 0.2. The largest transmittance difference detected using the UV-visible spectrophotometer was observed at a 590-nm wavelength. Second, the commercialized RUT kit also showed a gradual color change according to the pH change detected using the UV-visible spectrophotometer. Third, 13 cases of negative RUT results with a biopsy specimen and 16 of positive RUT results were collected. The transmittance detected using the UV-visible spectrophotometer showed a clear division between the positive and negative RUT groups; the largest difference was observed at a 559-nm wavelength. The lowest transmittance in the negative RUT group was 64, while the highest in the positive RUT group was 56, at the 559-nm wavelength. The UV-visible spectrophotometry reading showed a consistency of 92.7% compared with that of manual reading. CONCLUSION: A transmittance of 60 at a 559-nm wavelength detected using UV-visible spectrophotometer can be used as a cutoff value for interpreting RUT results; this will help develop an automatic RUT kit reader with a high accuracy.

Ultrarapid and ultrasensitive electrical detection of proteins in a three-dimensional biosensor with high capture efficiency.

The realization of a high-throughput biosensor platform with ultrarapid detection of biomolecular interactions and an ultralow limit of detection in the femtomolar (fM) range or below has been retarded due to sluggish binding kinetics caused by the scarcity of probe molecules on the nanostructures and/or limited mass transport. Here, as a new method for the highly efficient capture of biomolecules at extremely low concentration, we tested a three-dimensional (3D) platform of a bioelectronic field-effect transistor (bio-FET) with vertically aligned and highly dense one-dimensional (1D) ZnO nanorods (NRs) as a sensing surface capped by an ultrathin TiO2 layer for improved electrolytic stability on a chemical-vapor-deposited graphene (Gr) channel. The ultrarapid detection capability with a very fast response time (∼1 min) at the fM level of proteins in the proposed 3D bio-FET is primarily attributed to the fast binding kinetics of the probe-target proteins due to the small diffusion length of the target molecules to reach the sensor surface and the substantial number of probe molecules available on the largely increased surface area of the vertical ZnO NRs. This new 3D electrical biosensor platform can be easily extended to other electrochemical nanobiosensors and has great potential for practical applications in miniaturized biosensor integrated systems.

Cerium-doped yttrium aluminum garnet hollow shell phosphors synthesized via the Kirkendall effect.

We report, for the first time, the synthesis of the Y3Al5O12:Ce(3+) hollow phosphor particles with a uniform size distribution via the Kirkendall effect, characterized by using a combination of in situ X-ray diffraction and high-resolution transmission electron microscopy analyses as a function of calcination temperature. The formation of hollow Y3Al5O12:Ce(3+) particles was revealed to originate from the different diffusivities of atoms (Al and Y) in a diffusion couple, causing a supersaturation of lattice vacancies. The optical characterization using photoluminescence spectroscopy and scanning confocal microscopy clearly showed the evidence of YAG (yttrium aluminum garnet) hollow shells with emission at 545 nm. Another advantage of this methodology is that the size of hollow shells can be tunable by changing the size of initial nanotemplates that are spherical aluminum hydroxide nanoparticles. In this study, we synthesized the hollow shell particles with average diameters of 140 and 600 nm as representatives to show the range of particle sizes. Because of the unique structural and optical properties, the Y3Al5O12:Ce(3+) hollow shells can be another alternative to luminescence materials such as quantum dots and organic dyes, which promote their utilization in various fields, including optoelectronic and nanobio devices.