Fig. 1.

Experimental design. The CD14 biosensor is comprised of an avidin-conjugated antibody targeting module and a set of biotin-conjugated readout modules for dual functionality (NMR/fluorescence) to selectively label high CD14-expressing cells. Multiple avidin molecules are conjugated to each targeting module, an anti-CD14 specific antibody, but for schematic simplicity, only one avidin is depicted per antibody. Step 1. The biosensor can be applied in two different ways: sequential incubation (A and B), in which cells are incubated with the targeting module, followed by the readout modules, or via incubation with the complete construct (C), in which the targeting modules and readout modules are preconnected. Step 2. Cells are washed to remove any unbound biosensor and harvested. Step 3. Cellular uptake, biosensor specificity and cellular localization can be evaluated via the fluorescence readout module. Step 4. The cell suspensions are placed into separate compartments within an NMR double phantom. The hp-Xe is bubbled through the samples for xenon MRI measurements. Step 5. Illustrative xenon MRI shows a cross-section of the NMR double phantom. The CEST effect encodes the localization of the CrA readout module in the compartment containing the high-CD14-expressing cells.