Millifluidic chip with a modular design used as a sample pretreatment cartridge for flour and flour food products.

The integration of sample pretreatment remains one of the hurdles towards a rapid, automated micro total analytical system (µ-TAS) for real samples. In this paper, a modular design, which was used for sample preparation, has been developed as the polydimethylsiloxane (PDMS) millifluidic chips with channels at a millimeter level. Multiple functional units, including extraction, filtration, mixing and solid phase extraction (SPE), for sample pretreatment were integrated in one chip. In this chip, each functional unit was connected by pump tubings and one-way valves in series to form a fully automated system. Based on the modular design, multiple functional units have been combined in different sequences according to practical needs. In addition, the proposed system has characteristics of miniaturization, portability, and real-time application. Herein, spiked benzoyl peroxide (BPO) in flour samples was used as a model compound to study the system's performances. With a portable integrated Raman spectrometer for detection, the detection limit of BPO was 0.017gkg-1, with a linear relationship from 0.025 to 0.5gkg-1. This modular design was demonstrated to be effective and it can be expanded for pretreatment of other food samples.

Responses of oral epithelial cells to dental resin components.

The light-polymerized resins used in dentistry and their various constituents have been shown to produce significant levels of cytotoxicity, depending upon the material and the cell type exposed to it. These responses include altered cell growth and macromolecule synthesis. The current study examined the effects of several resin components on growth and lipid metabolism of oral epithelial cells. Resin discs were fabricated from triethyleneglycol dimethacrylate (TEGDMA) as received from the manufacturer and after removal of the stabilizer methyl ether hydroquinone (MEHQ). Some discs also contained the initiators benzoyl peroxide (BPO) and camphoroquinone (CQ), and/or an activator, dimethylaminoethyl methacrylate (DMAEMA). After polymerization, the ability of components to elute from the discs and alter cell growth and lipid synthesis were assayed by a colorimetric method and thin layer chromatography respectively. Purified TEGDMA had little effect on the cells' growth or lipid metabolism, while TEGDMA containing MEHQ did inhibit growth as well as total polar lipid synthesis. Eluates from discs containing DMAEMA inhibited cell growth as well as decreasing polar lipid formation. However, this same material produced increased synthesis of diglycerides and cholesterol esters. Eluates from BPO-containing discs, as well as those with CQ, with or without DMAEMA resulted in increased levels of diglycerides. These results demonstrate that even after polymerization, components used in dental resins may elute into the immediate environment and alter various cell metabolic processes.