Highly Sensitive Detection of Physiological Spinsin a Microfluidic Device.

Sensing and imaging paramagneticspecies under physiological conditionsis a key technology in chemical and biochemical analytics, cell biology,and medical sciences. At submicrometer length scales, nitrogen-vacancy(NV) centers in diamond offer atom-sized probes for magnetic fields.We show that spin relaxation of an ensemble NV sensor allows sensingof adsorbed and freely diffusing manganese(II) ions and adsorbed ferritin.Sensitivities approach 175 Mn ions and 10 ferritin proteins per diffractionlimited spot under ambient conditions. [ABSTRACT FROM AUTHOR]