Techniques regarding integrated purification-detection devices for detecting one or more biomarkers are provided. For example, one or more embodiments described herein are directed to an apparatus, comprising a housing and a microfluidic chip contained within the housing. The microfluidic chip comprises a separation unit that separates, using one or more nano deterministic lateral displacement (nanoDLD) arrays, target biological entities having a defined size range from other biological entities included in a biological fluid sample. The microfluidic chip further comprises a detection unit that facilitates detecting presence of one or more biomarkers associated with the target biological entities using one or more detection molecules or macromolecules that chemically reacts with the one or more biomarkers.