This research presents a microfermentor integrated into an optical fiber sensor based on quasi-elastic light scattering (QELS) to monitor and swiftly identify cellular growth kinetic parameters. The system uses a 1310 nm laser light that is guided through single-mode silica optical fibers to the interior of perfusion chambers, which are separated by polycarbonate membranes (470 nm pores) from microchannels, where a culture medium flows in a constant concentration. The system contains four layers, a superior and an inferior layer made of glass, and two intermediate poly(dimethylsiloxane) layers that contain the microchannels and the perfusion chambers, forming a reversible microfluidic device that requires only the sealing of the fibers to the inferior glass cover. The QELS autocorrelation decay rates of the optical signals were correlated to the cells counting in a microscope, and the application of this microsystem to the monitoring of alcoholic fermentation of Saccharomyces cerevisiae resulted in the kinetic parameters of KM = 4.1 g/L and μm = 0.49 h−1. These results agree with both the data reported in the literature and with the control batch test, showing that it is a reliable and efficient biological monitoring system.

Recent progress in the design of nanocarriers for the codelivery of a drug/drug, drug/gene, and gene/gene for synergistic cancer therapeutic effects.

Localized release of nucleic acid therapeutics is essential for many biomedical applications, including gene therapy, tissue engineering, and medical implant coatings. We applied the substrate-mediated transfection and layer-by-layer (LbL) technique to achieve an efficient local gene delivery. In the experiments presented herein, we embeded lipoplexes containing plasmid DNA encoding for enhanced green fluorescent protein (pEGFP) within polyelectrolyte alginate-based microgels composed of poly(allylamine hydrochloride) (PAH), chondroitin sulfate (CS), and poly-L-lysine (PLL) with diameters between 70 and 90 μm. Droplet-based microfluidics was used as the main process to produce the alginate (ALG)-based microgels with discrete size, shape, and low coefficient of variation. The physicochemical and morphological properties of the polyelectrolyte microgels were characterized via optical microscopy, scanning electron microscopy (SEM), and zeta potential analysis. We found that polyelectrolyte microgels provide low cytotoxicity and cell− material interactions (adhesion, spreading, and proliferation). In addition, the microsystem showed the ability to load lipoplexes and a loading efficiency equal to 83%, and it enabled in vitro surface-based transfection of MCF-7 cells. This approach provides a new suitable route for cell adhesion and local gene delivery.

BACKGROUND: Microfluidics offers itself as a potential platform for optimizing microbial growth in different substrate concentrations using a single assay. The aim of this study was to construct a reversible microfluidic device for monitoring the bacterial growth in chambers with different substrate concentrations with its respective technical triplicates. The convective concentration gradient generator (CCG) system was constructed with three inlets for solutions with different concentrations that distributed them to the sequential cultivation chambers (CCs). A perfusion microbioreactor system (PM) was constructed using a commercial polydimethylsiloxane (PDMS) sheet and glass, with an adapted semi-permeable membrane system to constrain the cells within the CC. Cell growth of a fluorescent Escherichia coli JM109 was monitored by fluorescence microscope with time-lapse technique. RESULTS:The growth profile of E. coli with different streptomycin concentrations and its specific growth rates ( x ) in the microfluidics device ( x of 0.0088 and 0.0092 h −1 ) were compared in batch cultivations, which show no significant difference between the two methods. In addition, the half maximal inhibitory concentration (IC 50 ) values indicate that continuous perfusion surpasses consumption of the tested drug. CONCLUSION:The results demonstrate the efficiency of the microfluidic device for cell cultivation and its applicability in industrial biotechnology, allowing rapid screening of multiple parameters. Bacterial growth behavior within the PMSince fluorescent E. coli was used, cell growth behavior was easily momitored by analyzing fluorescence in the cultivation chambers (Supporting information S4). Two microbioreactor systems were built that differed with respect to the materials used in the cultivation chamber: (i) PDMS-PDMS (lateral wall and base) with hydrophobic characteristics; and (ii) PDMS (wall)-glass (base) with J Chem Technol Biotechnol 2019; 94: 712-720

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