An apparatus for measuring a concentration of amyloid-beta within a chiral solution includes signal generation circuitry for generating a first signal having an applied first orbital angular momentum signature and applying the first signal to the chiral solution. A detector for receiving the first signal after the first signal passes through the chiral solution and determining the concentration of amyloid-beta within the chiral solution based on a detected second orbital angular momentum signature received from the chiral solution that comprises an amplitude measurement and a phase measurement.