Detection of cerebrospinal fluid

A method of detecting asialo-transferrin in a biological sample comprising:

• a) contacting the biological sample with a first plurality of transferrin-binding antibodies conjugated to nanoparticles;
• b) centrifuging the product of step a) so as to separate and obtain conjugates of transferrin bound to transferrin-binding antibodies conjugated to nanoparticles;
• c) contacting the conjugates obtained in step b) with a lateral flow device, and observing if asialo-transferrin bound antibodies bind to a second plurality of transferrin-binding antibodies affixed to the lateral flow device, wherein if such antibodies bind then asialo-transferrin has been detected in the biological sample and wherein if no asialo-transferrin bound antibodies bind to the second plurality of transferrin-binding antibodies affixed to the lateral flow device then asialo-transferrin has not been detected in the biological sample,
• and wherein the lateral flow device comprises in sequential order:
• a portion comprising a fixed sialic acid-specific lectin;
• and
• a portion comprising a second plurality of transferrin-binding antibodies affixed to the lateral flow device;
• and
• a portion comprising a plurality of anti-antibody antibodies affixed to the lateral flow device.