Ultrasensitive Detection of DNA and Ramos Cell Using In Situ Selective Crystallization Based Quartz Crystal...

Herein we introduce the first successful assay of biomolecule by in situ selective crystallization based quartz crystal microbalance (QCM). Selective crystallization of CaCO₃ on QCM sensor surface was utilized as an efficient mass amplification strategy and enhanced the sensitivity of QCM significantly. High specificity is guaranteed by the cooperation of two functional groups: -N(CH₃)₃ and -COOH. Passivation of sensor surface is realized by self-assembly of -N(CH₃)₃, which effectively inhibited the nonspecific crystallization. The DNA target is detected through hybridization of probe DNA labeled with -COOH, which can effectively promot the in situ surface crystallization of CaCO₃. The concentration of target DNA is reflected by the frequency shift of QCM which is directly induced by the surface crystallization. The selective crystallization based QCM platform is simple, straightforward, high sensitive, and high specific. We demonstrate the excellent LOD (2 aM DNA) and a linear range of 10aM to 1 nM for DNA. Detection of Ramos cells are also realized with a LOD of five cells and a linear range of 5-6000 cells.