I am looking into synaptic membrane receptor numbers and would thus like to perform postsynaptic density (PSD) isolation, which includes a synapto(neuro)somal preparation. This usually requires a sucrose density gradient centrifugation step. As I am studying the amygdala on individual rodent brains (rat), meaning I get one sample per brain (no pooling tissue together), my homogenates are only 100-200 µL in volume. My issue is with the sucrose density gradient step volumes: I'm using 0.5 mL (500 µL) ultracentrifuge tubes, so I'd have to make, say, sucrose steps of only 50 µL, which classically should be at least around 1 mL. If anyone has ever tried this, I would be very grateful if you could share your experience with me. Thank you.