Enhanced absorbance detection system for online bacterial monitoring in digital microfluidics.

We report a fully integrated digital microfluidic absorbance detection system with an enhanced sensitivity for online bacterial monitoring. Through a 100 µm gap in the chip, our optical detection system has a detection sensitivity for a BCA protein concentration of 0.1 mg mL-1. The absorbance detection limit of our system is 1.4 × 10-3 OD units, which is one order of magnitude better than that of the existing studies. The system's linear region is 0.1-7 mg mL-1, and the dynamic range is 0-25 mg mL-1. We measured the growth curves of wild-type and E. coli transformed with resistance plasmids and mixed at different ratios on chip. We sorted out the bacterial species including highly viable single cells based on the difference in absorbance data of growth curves. We explored the changes in the growth curves of E. coli under different concentrations of resistant media. In addition, we successfully screened for the optimal growth environment of the bacteria, in which the growth rate of PET30a-DH5α (in a medium with 33 µg mL-1 kanamycin resistance) was significantly higher than that of a 1 mg mL-1 resistance medium. In conclusion, the enhanced digital microfluidic absorbance detection system exhibits exceptional sensitivity, enabling precise bacterial monitoring and growth curve analysis, while also laying the foundation for DMF-based automated bioresearch platforms, thus advancing research in the life sciences.

Stable solution of induced modulation instability.

In this paper,we discussed the nonlinear evolution of modulation instability and the steady-state process of induced modulation instability in sine-oscillatory response nonlocal nonlinear media. With plane wave plus perturbation as initial conditions, we simulated the long-term evolution of modulation instability in the nonlocal nonlinear Schrodinger equation with sine-oscillatory response numerically. For the input of modulated wave, the approximate analytical solution of the stable solution of the equation is obtained under the assumption that only the fundamental wave and the first harmonic wave are present. For the input of modulated wave with arbitrary harmonic waves, we obtained the exact numerical solution of the stable solution of the induced modulation instability.

DNA condensation induced by ruthenium(II) polypyridyl complexes [Ru(bpy)(2)(PIPSH)](2+) and [Ru(bpy)(2)(PIPNH)](2+).

Two novel DNA-intercalating ruthenium(II) complexes, [Ru(bpy)(2)(PIPSH)](2+) and [Ru(bpy)(2)(PIPNH)](2+), have been synthesized and characterized. Gel retardation assay, atomic force microscopy, and dynamic light scattering studies show that both complexes can induce the condensation of originally circular plasmid pBR322 DNA to particulate structures under neutral conditions.