Concentration gradient definition
For example, soluble concentration gradients of vascular endothelial growth factor (VEGF) have been shown to promote endothelial cell migration ( Shamloo et al., 2012), interleukin-8 (IL-8) gradients are known to direct migration of human neutrophils ( Vasaturo et al., 2012), whilst concentration gradients of neurotrophic factors and sonic hedgehog (Shh) have a proven role in axonal guidance ( Xu et al., 2018). Biomolecular concentration gradients established by diffusion have been implicated in a number of fundamental physiological and pathological processes occurring throughout development and adulthood i.e., embryogenesis ( Christian, 2012), axonal guidance ( Cao and Shoichet, 2001), and chemotaxis ( Qasaimeh et al., 2018). The in vivo microenvironment is modulated by the precise orchestration between a multitude of chemical, physical, and biological stimuli influencing cellular behavior. We believe this device presents as a convenient and useful tool that can be easily adopted for study of cellular response in gradient-based assays. The compatibility of our platform with cell culture was demonstrated using a LIVE/DEAD ® assay on terminally differentiated SH-SY5Y neurons.
![concentration gradient definition concentration gradient definition](http://image2.slideserve.com/4587272/concentration-gradient-n.jpg)
The steepness of gradients generated are within appropriate range to elicit response in certain cell types. FITC-Dextran (40 kDa) took longer to establish in all hydrogel setups. Our model molecules sodium fluorescein (376 Da) and FITC-Dextran (10 kDa) quickly established a concentration gradient that was maintained out to 96 h, with 24 hourly replenishment of the source and sink reservoirs. The presence of collagen within the agarose-collagen co-gel increased the mechanical properties of the gel.
![concentration gradient definition concentration gradient definition](https://content.byui.edu/file/a236934c-3c60-4fe9-90aa-d343b3e3a640/1/module5/images/chamber3.gif)
#Concentration gradient definition generator#
Here, we present the design and fabrication of a compartmentalized polydimethylsiloxane diffusion-based gradient generator capable of sustaining concentration gradients of soluble molecules within thick (5 mm) and thin (2 mm) agarose and agarose-collagen co-gel matrices. Despite this, there remains a current paucity of simplistic, convenient devices capable of generating biologically relevant concentration gradients for cell culture assays. This has motivated the development of numerous in vitro gradient-generators allowing researchers to study cellular response in a precise, controlled environment.