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A 3D printed lab-on-a-chip flow cytometer device for particle and cell analysis
Sarah Hampson, Research Student, Loughborough University
Additive manufacturing, also known as 3D printing, is currently being explored as an alternative fabrication method for microfluidic systems[1,2]. As 3D printing capabilities advance, its rapid production process (enabling greatly accelerated prototyping stages), three-dimensional design freedom and wide material choice give it the power to completely revolutionise the fields of microfluidic devices and lab-on-a-chip technologies[3, 4, 5, 6].
Microfluidic particle-based analyses and assays have been developed for a wide range of bioanalytical applications[7], but the design of such systems remains challenging due to the tendency for fouling[8]. A solution is flow cytometry, which involves particle or cell analysis in-flow via hydrodynamic focusing, which also permits coupled, on-the-fly processes such as continuous separation[9] and automated control[10].
Here we present a flow cytometer lab-on-a-chip device for single-particle and single-cell analysis that has been fabricated by stereolithography. The chip integrates optical fibers for UV-visible analysis and costs £10 to produce (in contrast to £30-100k commercial instruments), allowing future application in disposable point-of-care devices. Hydrodynamic focusing power of both dye streams and particles is demonstrated, as well as the ability to carry out multiplex analyses. Analysis optimisation was carried out via application of a genetic algorithm to a wide range of flow variables.
Synthesis and Assembly of Gold Particles on an Emulsion Droplet; Nanoparticles, Nanosheets and Core-Shell Particles within the microfluidic channel.
Suchanuch Sachdev, Research Student, Loughborough University
The synthesis and assembly of materials at the interface between two immiscible liquids is an area of growing interest. A variety of experimental setups from Pickering emulsions[1], electro and electro less deposition[2,3] allow materials to be assembled and synthesised with relative ease. The syntheses of gold (Au) nanomaterials were formed using emulsions droplets within the microfluidic channel.
By placing the Au salt in the aqueous phase and decamethylferrocene in the organic phase, Au nanoparticles (NP) or nanosheets (NS) were formed instantly. The addition of Magnetite (Fe3O4) NP into the organic phase, produces a shell of Fe3O4 particles around the as formed AuNP. As a comparison, AuNP’s that were first synthesized and placed into the aqueous phase allowed emulsion droplets to be formed without the need for a surfactant and in the presence of Fe3O4 NP’s in organic phase formed Au shell around the Fe3O4 core. This simple method of tuning the particle shape and core@shell synthesis is the first reported using emulsion droplets, and we present X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) analysis of the products.
Acoustically-driven thread-based tuneable gradient generators
Shwathy Ramesan, PhD Student, RMIT University
A thread-based microfluidic system offers a simple, low-cost, disposable and biodegradable alternative to conventional microfluidic systems. While there have been applications in gradient formation, the dynamic tuneability in biodegradable substrates using a thread-based microfluidic system has not been explored.
The authors of this work have developed an acoustically-driven thread-based tunable gradient generator to permit ‘on-the-fly’ dynamic manipulation of the flow. Precisely, generation of stable and continuous concentration gradient, in a serial dilution and re-combination network, was carried out with the application of high frequency sound waves. The chip-scale device induced convective transport through the porous, biodegradable and biocompatible cellulose threads leading to the formation of rapid, precise and uniform liquid flow which cannot be achieved solely by the passive capillary transport. Additionally, a proof-of-concept working of the gradient generators is shown by implantation of thread-based network in a three-dimensional hydrogel construct. This setup closely mimics the in-vivo tissue microenvironment typically observed in microfluidic chemotaxis studies and cell culture systems.
Continuous Enzymatic Hydrolysis of Glycyrrhizic Acid in Microchannel Reactor
Seref Akay, Research Assistant, Ege University
Licorice demonstrates a variety of pharmacological activities, including antiulcer, anti-inflammatory, antiviral, anticancer, and anti-HIV activity. Also, it is used broadly in the tobacco, food, confectionary and pharmaceutical industry all over the world. Glycyrrhetinic acid (GL) and Glycyrrhizic acid (GA) are the main active constituents of licorice. The aglycone GL is considered to be ultimately responsible for the pharmacological effects of licorice. Orally administered GA is almost completely transformed by removal of two glucuronic acid moieties in the intestinal system and reaches the systematic circulation as GL. Microreactors are generally described as miniaturized reaction systems fabricated by using methods of microtechnology and precision engineering. In this study, ß-glucuronidase and GA solutions pumped into a 26 cm long single channel microreactor with 920X400 µm dimensions. Different flow rates between 5-100 µl/min were applied. Samples were collected from the microchannel and analyzed by HPLC. The results revealed that, the increase in the flow rate increased the enzymatic conversion. The maximum conversion was obtained under 50 µl/min flow rate for both enzyme and GA solution where 25% of GA was converted to GL (8%) and intermediate products (17%). Similar results were recorded with the highest flow rate (100 µl / min). Enzymatic conversion was not observed at a flow rate of 5 µl / min which is the lowest flow rate. The conversion yields obtained in a short time can be attributed to advantages of microchannel reactor. The results have been found promising for the biotransformation of bioactive compounds.
Acknowledgements
The financial support provided by TUBITAK (113M050) is highly appreciated.
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