Waret Veerasai

Comparison of Gravitational SPLITT Fractionation with Gravitational Settling for Separating Micron Size Particles

Abstract The performance of gravitational Split‐flow thin‐channel (GrSPLITT) fractionation has been compared with conventional gravitational settling (GrSettling) method. Two modes of GrSPLITT (full‐feed depletion (FFD) mode and transport (TS) mode) were employed. Silica and natural river particles were used to test these techniques. The particles were fractionated at the following cutoff diameters (d c ) 2, 4, 6, 10, 14, and 20 µm. The fractions with diameter <d c were analyzed for their particle size distribution by both optical or scanning electron microscopy and image analysis. Several parameters were used to objectively compare the efficiency of the methods. Almost all of the tests showed that TS‐GrSPLITT had the highest separation efficiency. The ranking of FFD‐GrSPLITT and GrSettling were considered to be of equal ranking as the order varied for the different parameters and samples used.

Detecting DNA-DNA Hybridization at 3-Mercaptopropionic Acid Self-Assembled on Tin-Doped Indium Oxide Film with Electrochemical Measurement

Self-assembled monolayers (SAM) of 3-mercaptopropionic acid (MPA) were applied on tin-doped indium oxide (ITO) surfaces and used as a working electrode for sensing DNA hybridization. The concentration of probe single stranded DNA (ssDNA), complemented with target DNA, was optimized for the highest yield immobilization on MPA/ITO platform. The ssDNA/MPA/ITO was allowed to hybridize to target DNA prepared from PCR amplification that first tested by the synthesized complementary sequences. Both cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were employed for investigating probe ssDNA immobilization and target DNA hybridization. For fast and low concentration detecting purposes, methylene blue (MB) coupled with differential pulse voltammetry (DPV) was used for detecting the target DNA hybridization events.