High Precision Biochips of Membrane Mimics for Blood Biomarker Assessment Multiple sclerosis (MS) is an immune-mediated, inflammatory demyelinating and neurodegenerative disease of the central nervous system. There has been tremendous effort in searching of biomarkers that are capable of distinguishing between MS disease and control, detecting inflammatory activity and the degree of neurodegeneration and demyelination/ remyelination. Despite a list of candidate biomarkers, most of them have not been validated, and therefore they are not clinically useful. Additionally, many of these marker candidates are from cerebrospinal fluid (CSF), which are difficult to evaluate routinely. Blood-based biomarkers, on the other hand, are of great value because of the ease in blood collection by a minimally invasive manner. However, evaluation of marker candidates in blood has met considerable difficulty due to issues of low abundance, complex background, and lack of technical capability to carry out effective screening. This proposal aims to develop a set of biochips with precise display of lipid antigens in the form of air-stable, robust membrane mimics arrays. These biochips will be combined with surface plasmon resonance imaging (SPRi) technique for assessment of biomarker detection in blood in a high throughput fashion. We will employ lithography and 3D printing technology to fabricate both the chip substrate and flow cells that enable better control of solution delivery, eliminate alignment steps and avoid index matching fluid, substantially simplifying the experimental procedure in SPRi measurement. SPRi is an attractive label-free technique for microarray analysis, offering high detection sensitivity without the need of a label, and enables various measurement functions to be carried out with simple instrument configuration.
Specific aims for this work include 1) fabrication of high performance array of membrane mimics for SPRi with photolithographic methods. A ganglioside array will be constructed with natural and synthetic lipid hosting environment for studies to understand how molecular display of antigens affects binding and marker screening in blood samples; 2) fabrication of highly integrated arrays of membrane mimics with 3D printing technology. We will characterize the performance of ganglioside arrays in detection of antibodies in blood and test a 3D printed flow system that can be assembled into biochips to form a cartridge-like unit; 3) assessment of analytical performance of the high precision biochips for detection of MS biomarkers in blood. The focus is to construct high quality arrays consisting of known and potential lipid antigens and carry out performance characterization in terms of sensitivity, working range and cross activity. We will also run clinical samples of MS patients from commercial sources to evaluate the effectiveness of this platform for biomarker screening as compared to lipid overlay array method.
The proposed research is relevant to public health because it will develop new analytical methods to facilitate biomarker research and its screening for multiple sclerosis (MS), the leading cause of neurological disability in young adults. We develop high precision microarray of membrane mimics that properly display lipid antigens in a cell-mimetic environment to maximize the interactions with antibodies, allowing close scrutiny of the potential binding events. The use of membrane mimics for construction of array elements also suppresses nonspecific interactions, allowing direct screening of biomarkers from bodily fluids including CSF and blood with advanced label-free technology.
