Characterization of a membrane-based gradient generator for use in cell-signaling studies

Abstract

This paper describes a method to create stable chemical gradients without requiring fluid flow. The absence of fluid flow makes this device amenable to cell signaling applications where soluble factors can impact cell behavior. This device consists of a membrane-covered source region and a large volume sink region connected by a microfluidic channel. The high fluidic resistance of the membrane limits fluid flow caused by pressure differences in the system, but allows diffusive transport of a chemical species through the membrane and into the channel. The large volume sink region at the end of the microfluidic channel helps to maintain spatial and temporal stability of the gradient. The chemical gradient in a 0.5 mm region near the sink region experiences a maximum of 10 percent change between the 6 and 24 h data points. We present the theory, design, and characterization of this device and provide an example of neutrophil chemotaxis as proof of concept for future quantitative cell-signaling applications.

An agarose-based microfluidic platform with a gradient buffer for 3D chemotaxis studies

“…It is involved in a number of important processes including immune responses, tissue repair, and tumor cell metastasis, and understanding the molecular mechanisms governing directed cell migration is important for the development of new therapeutic strategies. Even though most, if not all, physiological and pathophysiological chemotaxis occurs within 3D environments, most in vitro chemotaxis experiments have been conducted in 2D settings (Abhyankar et al 2006;Boyden 1962;Frevert et al 2006;Irimia et al 2006;Irimia et al 2007;Jiang et al 2005;Li Jeon et al 2002;Shamloo et al 2008;Diao et al 2006;Cheng et al 2007;Sun et al 2008;Zigmond 1977).…”

Organic electronics for precise delivery of neurotransmitters to modulate mammalian sensory function

“…Furthermore, delivery should preferably be achieved with minimal fluid flow, as liquid flow can lead to undesirable effects, e.g., chemical gradient disruption 9 , or increased pressure in compartments with limited volume. Non-convective delivery would enable introduction of biosubstances per se into small compartments in organs, e.g., the cochlea.…”

A membrane-based microfluidic device for mechano-chemical cell manipulation

“…Several microfluidic systems have been proposed in which membranes or gel layers are used as interfaces through which chemicals can diffuse to the cells (Saadi et al 2007;Abhyankar et al 2006;Kim et al 2009;Cheng et al 2007). The microfluidic system proposed in this study has the following advantages.…”

“…Liu et al developed a microfluidic method for monitoring in real time the effect of an anticancer drug on cancer glioma cells (Liu et al 2010). Furthermore, to generate stable chemical gradients without producing shear stress over cultured cells, gradient barriers such as membranes (Abhyankar et al 2006;Kim et al 2009) or hydrogels (Saadi et al 2007;Cheng et al 2007;Mosadegh et al 2007) have been integrated in microfluidic devices. These systems allow establishing a controllable chemical gradient without affecting the fluid flow in the cell area.…”

“…They established the chemical gradient by separating the gradient channel and the cell culture channel with a polyester membrane and measured the uptake of the chemical by the cultured cells. Abhyankar et al (Abhyankar et al 2006) created a stable chemical gradient without requiring fluid flow by diffusion through a membrane from a chemical source region. Saadi et al (Saadi et al 2007) developed a microfluidic device for generating stable concentration gradients based on a two-compartment diffusion system consisting of two large parallel channels connected by horizontal microgrooves filled with collagen gel.…”