Methods and materials for treating cancer

A method for detecting a target polypeptide in a fluid sample, the method comprising:

• providing a microfluidic chip comprising a) a capture surface comprising a plurality of multi-valent capture antibodies, wherein said capture surface has a side comprising a biotin-poly(ethylene)glycol (PEG) coating, wherein said capture antibodies are conjugated to said biotin-PEG moieties via a deglycosylated avidin linker, and wherein said avidin linker conjugates a plurality of capture antibodies to each biotin moiety on said biotin-PEG coating;
• and b) a chip enclosure comprising a flow channel disposed on said capture surface, wherein said flow channel is in fluid contact with said capture surface, and wherein said flow channel comprises staggered herringbone grooves on an inner channel surface;
• infusing the fluid sample through the flow channel of said microfluidic chip, wherein said target polypeptide, when present in said fluid sample, binds to said capture antibodies;
• infusing fluorophore-labeled detection antibodies through the flow channel of said microfluidic chip, wherein said target polypeptide, when bound to said capture antibodies, binds to said fluorophore-labeled detection antibodies;
• imaging the presence or absence of said fluorophore-labeled detection antibodies in at least 10 regions of said capture surface, wherein said imaging comprises time-stream total internal reflection (TIRF) microscopy, wherein said imaging can spatially resolve individual clusters of target proteins, and wherein each cluster is a fluorescent spot;
• performing a fluorescent shape analysis, wherein the fluorescent shape analysis comprises determining a number of fluorescent counts, wherein said determining comprises generating 2D scatter plots of σ and intensity of each fluorescence spot, converting said 2D scatter plots into 2D histograms, converting said 2D scatter plots into a heat map, and correcting for detection errors;
• and
• determining the presence of said target polypeptide, wherein said number of fluorescent counts corresponds to the presence of said target polypeptide.