Microfluidic method

Bioscience (BPS) used recombinant HDACs prepared in baculovims systems Andrianov et al. used batch-mode capture for recombinant HDAC preparations Balasubramanian ct al. performed continuous protease-coupled en2yme assays for recombinant HDAC activit) Kozikowski ct al. used a microfluid method for activities Li ct al. and Richon ct al. used immunopredpitated HDAC proteins for reactions. 

In a cell manipulation experiment, a constriction together with two narrow channels ( 50 pm) at the corner of a large channel were fabricated on a PDMS chip (see Figure 8.12). This microfluidic method was devised to remove cumulus cells from individual bovine cumulus-oocyte complexes before in vitro fertilization. In natural fertilization, sperms release hyaluronidase that attack... 

FIGURE 8.3 a-Selective glycosylation of KDO with a disaccharide acceptor using the microfluidic method. Alloc, allyloxycarbonyl Cbz, benzyloxycarbonyl, PMB, p-methoxybenzyl. 

FIGURE 8.4 a-Selective glycosylation of monosaccharide acceptors with KDO using the microfluidic method. 

Microfluidics - Method and Design 237 Utility of Microfluidics for Crystallization 242 References 253... 

A precondition for miniatiuization of the assay volume to a few microliter is the availability of reliable and versatile liquid-handling tools for precise metering and delivery of microliter and nanoliter aliquots of compound solutions, assay reagents, and biological materials. Low-volume liquid handlers in the life sciences utilize a variety of basic microfluidic methods for precise dosage of the aliquot volume being transferred, including ... 

Bodmeier, R. Chen, H. Hydrolysis of cellulose acetate butyrate pseudolatexes prepared by a solvent evaporation—microfluidization method. Drug Dev. Ind. Pharm. 1993, 19 (5), 521-530. 

It should be noted that the microfluidization process involves a very high shearing force that can potentially damage the structure of material to be encapsulated (40 5). Another disadvantage of the microfluidization method is material loss, contamination and being relatively difficult to scale-up (44). 

For this purpose, Li s group reported a simple multi-functional particle detection PDMS chip [17]. This chip generates liquid flow and particle motion electrokinetically, and uses two pairs of parallel optical fibers embedded in the chip to measure particle speed and size, and to count particles. More recently, a new microfluidic method was developed to counting the particles flowing through microchannels, not by the optic method as described previously, but by an electric method. This method is called the microfluidic differential resistive pulse sensor method [18]. Figure 6 below illustrates the principle of this method. 

To overcome these limitations imposed on conventional and microfluidic methods for size separation, hydrophoretic methods have been developed. Here we provide a review of the methods for continuous size separation of microparticles, blood cells and cell-cycle synchrony, and for sheathless focusing of cells without external fields and sheath flows in microfluidic devices. We describe details of the separation mechanism and its application to particle and cell manipulation, comparing its advantages and disadvantages with other microfluidic methods. Finally, we present some challenges of the hydrophoretic technology. 

Hydrophoresis offers advantages of a sheathless method, passive operation, and single channel. These advantages can make this separation technique a solution to the challenging problem of conventional separation methods. Here, we provide a detailed review of hydrophoretic methods for particle and cell manipulation, comparing their advantages and disadvantages with other microfluidic methods. 

An ideal on-site detection system would be inexpensive, sensitive, fully automated, reliable, multiplex sample handling, and detect a broad range of explosives. The advent of microfluidic lab-on-a-chip technology might offer such a detection system. Microfluidic capillary electrophoresis chips have been utilized for the detection of nitroaromatics such as TNT, DNT, NT, and DNB [9-12]. Due to the good redox properties of nitroaromatics and the inherent suitability for miniaturization, most of the microfluidic methods so far used electrochemical methods for detection. The individual components of nitroaromatics can be detected in the capillary electrophoresis chips (analyte-specific) unlike the colorimetric methods (class-specific) where nitroaromatics are detected broadly. 

Table 1 summarizes the advantages and disadvantages of established chemotaxis assays, including microfluidic methods. In the following sections, we discuss methods for developing two new types of microfluidic chemotaxis systems (1) a pPlug model... 

Although silica-based purifications of DNA and RNA are, by far, the most common microfluidic methods for isolation of nucleic acids, there have also been other solid phases and methods explored... 

The majority of microfluidic methods produce droplet using passive devices generating a uniform, evenly spaced, continuous stream of droplet, whose volume ranges from femtoliters to nanoliters. Their operational modes take advantage of the characteristics of the flow field to deform the interface and promote the natural growth of interfacial instabilities, avoiding in this way the necessity of any local external actuation. Droplet polydispersity, defined as the ratio between the standard deviation of the size distribution and the mean droplet size, can be as small as l%-3%. 

G. F. Christopher and S. L. Anna, Microfluidic methods for generating continuous droplet streams. Journal of Physics D Applied Physics, 40, 319-336, 2007. 

Capacitance-based microfluidic sensors have emerged as a powerful tool and been widely used in sensing pressure, position, biological cells, etc., since it has many advantages such as low cost and being compact, which makes capacitance-based microfluidic sensors of great potential use for point-of-care diagnosis. In this short entry, the mechanism, current applications, limitations, and perspectives of capacitance-based microfluidic method are introduced in details. 

Bogojevic D, Chamberlain MD, Barbulovic-Nad I, Wheeler AR (2012) A digital microfluidic method for multiplexed cell-based apoptosis assays. Lab Chip 12(3) 627-634... 

Similarly, Lan et al. [7] developed a one-step microfluidic method for fabricating nanoparticle-coated patchy particles. A coaxial microfluidic device was employed to produce Janus droplets composed of curable phase and non-curable phase. The results showed that nanoparticles were dispersed either in the continuous fluid or the non-curable phase fluid. The nanoparticles (30 nm or 300-500 nm) were adsorbed onto the interface between these phases, and the curable phase was solidified by UV-irradiated polymerization. Thus, the patchy microparticles asymmetrically coated by nanoparticles were synthesized. They also employed Si02, TS-1, and fluorescent polystyrene nanoparticles as the coating materials to demonstrate the validity of the method. The microfluidic approach exhibited excellent controllability in morphology, monodispersity, and size for the nanocomposites. The morphology of the particles could be controlled from less than a hemisphere to a sphere by adjusting the flow rate ratio of the two dispersed phases. The method can be applied to other nanoparticles with specific surface properties. 

The microfluidic method of microparticle fabrication can be used to generate particles with controlled internal morphology [66]. This method allows for control of both the size and shape of the polymer droplets. The setup for microfluidic devices is more complicated compared to other methods however, it allows for easier control of the system. By having flows of different polymers, a microparticle with an inner core and outer shell made from different polymers can be produced [49]. The size of the particles produced by microfluidic devices can be controlled by the flow rate of the polymers. Fig. 11.3 depicts the use of a microfluidic system to fabricate (a) PLGA microparticles and (b) PLGA microparticles with an alginate shell. 

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