These clusters were more prone to be washed together off the substrate and resulted in a large amount of empty spots on the array
These clusters were more prone to be washed together off the substrate and resulted in a large amount of empty spots on the array. antibodies and therefore ensured the formation of high resolution B lymphocyte arrays. The cellCligand interaction specificity was investigated and the anti-CD19 decorated micropatterns presented a much higher cell-capturing rate (88%) than those modified by non-specific ligands (15% for anti-CD5 and 7% for streptavidin). The approach was verified to be biocompatible and the properties of the antibody-modified surface were maintained after 12 h cell culture. The Mifepristone (Mifeprex) HMDS monolayer formation and patterning Mifepristone (Mifeprex) processes, and the universal HMDS/biotin-BSA/streptavidin template, provide a very simple and convenient process to generate high resolution micropatterns of cell-adhesive ligands and are extendable to form arrays of other types of cells as well. Introduction The inception of micro-electro-mechanical systems (MEMS) in the late 1980s has enabled the miniaturization of transducers at the length scale commensurate with biological cells.1 The integration of microfluidic actuators, such as microvalves, micro-pumps, and micromixers, with on-chip biosensors has greatly improved the efficiency and sensitivity of biological assays.2,3 Current lab-on-a-chip technologies, with increased system level integration, have become the heart of point-of-care devices allowing for rapid detection, high diagnostic efficiency, and low Mifepristone (Mifeprex) reagent consumption.4 One attractive application is to use live cells as the biosensing elements in that their cellular machinery and signaling pathways can be exploited to enhance the specificity and sensitivity of the detection scheme.5 The phenomenal successes of microtransducer manufacturing in the past decades have shifted the research emphasis of lab-on-a-chip systems from device fabrication to the engineering of surface molecular properties. The focus now lies in improving the detection limit of biotransducers, which is essentially determined by the amount of non-specific molecular binding and strongly depends on the surface property of the device. For point-of-care diagnostics, live cell-based biosensors can be exploited to detect the presence of certain analytes in body fluids and screen for toxic reagents.6,7 Spatially controlling the organization of large quantities of cells into precisely defined regions, ideally at the single-cell scale, is also dependent on the modification of surface molecular properties.8C11 The invention of new biofunctional materials and advancements in surface molecular patterning are therefore always of great interest for point-of-care applications. Self-assembled monolayer (SAM), a well-ordered monomolecular layer formed spontaneously by the reaction of certain types of molecules with supporting solid materials, has been widely explored to modulate the surface properties in order to enhance or prevent cell attachment.12C14 Arrays of SAMs can be defined by a variety of micro- and nano- patterning methods such as microcontact printing,15 photolithography,16 scanning probe lithography,17 electron-beam lithography,18 and ink-jet printing.19 These micro- and nano- patterns of SAMs can be subsequently coupled with extracellular matrix (ECM) proteins or peptides, antibodies, and other biomolecules to NOV control the selective attachment of both anchorage-dependent and non-adherent cells to the substrates. Two typical families of SAMs are alkanethiol reacting with gold and organosilane reacting with oxidized surfaces.14 Mifepristone (Mifeprex) Compared to alkanethiol SAM formation which needs a special gold deposition procedure, organosilane SAMs can be directly formed on transparent substrates such as glass and quartz, which is especially applicable for biological studies to achieve high resolution imaging.20 Another essential requirement for high selective cell patterning is to render the areas beyond the desired cell-adhesion regions inert to resist bio-fouling. Among several non-fouling molecular systems, poly-(ethylene glycol) (PEG) has attracted increased interest in its effectiveness for preventing non-specific protein binding.13,21C23 The highly hydrated PEG chains can minimize the interaction of proteins with the substrate and thus suppress bio-fouling. The Mifepristone (Mifeprex) combination of SAM micropatterning and PEG passivation provides a powerful research tool for a variety of applications such as genomics, proteomics, drug discovery, and molecule or cell-based biosensing. In this paper, we demonstrated a molecular engineered system combining organosilane and PEG for the successful generation of large area two-dimensional B lymphocyte arrays. Hexamethyldisilazane (HMDS), a commonly used photoresist adhesion promoter in micromachining, was self-assembled on the glass substrate by vapor phase deposition and was patterned by photolithography. The patterned HMDS served as a template to anchor antibodies for immunocapturing the B cells. The background was passivated with PEG through the silanization reaction of PEGCsilane and hydroxyl group terminated glass surface in order to prohibit the non-specific protein binding. The PEG passivation process was verified to have no impact on pre-fabricated HMDS micropatterns and the effectiveness of PEG in.