Early stage, rapid, low-cost, and accurate detection of disease components in a biological fluid is critically important. A point of care device can use functionalized magnetic beads to facilitate this detection. The device can include a sample holder with a collection region. A magnet can be used to draw the functionalized nanoparticles bound to the disease component into the collection region, where the disease component is captured. A light source can shine a light beam through the collection region; and a detector can detect the light beam after traversing the collection region to determine whether the disease component is present in the sample.