Cinoxacin synthetic biology combines biology with engineering to design and build novel biomolecular components, networks, and pathways. It is well known that the features important for synthetic biology include modularity, standardization, and rigorously predictive models. In recent years, an increasing number of studies in synthetic biology have focused on constructing simple synthetic gene circuits that exhibit desired properties. Meanwhile, a large variety of functional genetic parts are characterized and assembled to construct biological circuits to program new biological behaviors, dynamics, and logical control. Standard biological parts, such as BioBricks from the “Registry of Standard Biological Parts” at MIT, USA, provide the foundation for designing and constructing synthetic biological systems. Therefore, a synthetic biological system can be achieved using synthetic biological methods and BioBricks for which gene expression can be precisely regulated and quantitatively and accurately measured. Ribosome binding site is a sequence where translation of mRNA into protein starts with. RBS efficiency can be Nodakenin different with binding strengths of various sequences with a ribosome, as a result, yields of protein will be different. In this study, we investigated a few RBSs with different binding strengths. Our aim was to combine the assembly of BioBricks and a bacterial quorum-sensing mechanism to build synthetic circuits to subtly control bacterial population density at different levels. Moreover, our current investigation systematically studied the functions of different components in regulating bacterial population density through quorum-sensing circuits. Therefore, our system provides an example and model for modulation of cell density in other field, such as fermentation industry, which requires to maintain bacterial growth 
at a desired density for a long time or to prolong the stationary phase of bacterial growth, so that the production of bacterial metabolites can be achieved. Synthetic biology holds promise for developing artificial systems to address challenges posed by major global problems such as health, environment, materials, and energy. It is advancing from the development of proof-ofconcept designs to a focus on core platforms, including DNA construction, parts libraries, computational design tools, and interfaces for manipulating and probing synthetic circuits. We generated a series of engineered E. coli cells by cloning all the essential components of a quorum-sensing circuit into the same plasmid of each engineered E. coli cell using the BioBrick standard assembly method. As a result, luxR and luxI expression levels in this system were regulated and coordinated by the promoter PlacO-1. Since it is an artificial simplified system, it can be an ideal platform to investigate how the quorum-sensing process works, such as by exploring its molecular signal pathway. Furthermore, the quorum-sensing process involves in well controlled regulations and responses, so that the sensor circuit can monitor subtle change of environmental stimuli to control its own population density. Therefore, it can be potentially used as a testing or alarming system to sense environmental change, such as pollution, or microbes outbreak. Glaucoma is an optic neurodegenerative disorder that leads to gradual loss of vision due to degeneration of the retinal ganglion cells. Two subtypes of primary glaucoma can be distinguished, primary open angle glaucoma and primary angle closure glaucoma, which are associated with different anatomical defects.