A microcapsule array for quantitative fluorescence detection of copper ions based on functional nucleic acid

This paper reports a portable, low-cost, user-friendly and ultrasensitive microcapsule array for quantitative fluorescence detection of copper ions based on functional nucleic acid strategy. Since the reagents are pre-sealed through ice printing technique and stored in frozen microcapsules before application, long-term stability of this device is guaranteed. Trace Cu²⁺ sample is simply injected into the thawy microcapsule by microsyringe, and after 15 minutes the fluorescence results are shown under an LED transilluminator. This assay shows great sensitivity with the minimum detection limit of 100 nM (100 fmol/μL) and specificity. Furthermore, it can be applied into other assays based on DNA fluorescence detection.