High Sensitive Detection Of Biomolecules On Chip Through Integrated Nanostructures

Fluorescent assays have been widely explored and become the gold standard for detecting myriad biomarkers in disease treatment and clinical diagnostics.However,due to reduced sample volume available and low concentration of analytes contained,the ability to push the limit of detection(Lo D)is of utmost significance to enhance the overall analytical performance of fluorescent assays and achieve early detection of various diseases.On the other hand,the Lo D of assays can be tremendously improved by nanostructures or nanoparticles due to the metal enhanced fluorescence.In resent years,various nanostructures are fabricated and dramatically improve the sensitivity of immunoassays.However,these nanostructures are usually prepared either by solution-phase method or advanced nanofabrication tools,which may involve cumbersome operation procedure or expensive equipment.Here,we report a novel microfluidic chip which integrates high aspect ratio gold nanorod(NR)arrays for high-sensitive fluorescent immunoassays of proteins.The microfluidic chip consists of a patterned layer made by polydimethylsiloxane(PDMS)and a glass substrate,which stores detection antibodies(d Abs)on the surface and integrates 3.5×2 mm2 areas of Au nanorods(NRs)bonded with capture antibodies(c Abs).Further,The PDMS device comprises a single sample inlet,flow resistors,a capillary pump with vents,a deposition zone aligning the d Abs stored on the glass substrate and a reaction chamber aligning the Au NRs detection area.Compared with conventional glass or PDMS plates,we have demonstrated one-step immunoassays by over 100-fold enhancement of fluorescent intensity.Leveraging on this chip,the limit of detection(Lo D)for goat Ig G reaches 1ng/ml within 5 min reaction time.More importantly,the fabrication and integration of these nanorods eliminate the requirement of expensive and time-comsuming nanofabrication equipment,such as e-beam lithography.The gold nanorod-based and capillary-driven microfluidic chips presented here can benefit for early diagnostics of various diseases.