A label-free method for the spatio-temporal mapping of protein secretions from individual cells in real time by using a chip for localized surface plasmon resonance (LSPR) imaging. The chip is a glass coverslip compatible for use in a standard microscope having at least one array of functionalized plasmonic nanostructures patterned onto it. After placing a cell on the chip, the secretions from the cell are spatially and temporally mapped using LSPR imaging. Transmitted light imaging and/or fluorescence imaging may be done simultaneously with the LSPR imaging.