Synthesis of tethered poly(N-isopropylacrylamide) for detection of breast cancer recurrence DNA

We have grafted temperature-responsive tethered poly(N-isopropylacrylamide) (PNIPAAm) onto silicon surfaces through atom transfer radical polymerization (ATRP) as a medium to extract human genomic DNA molecules from a biological specimen, namely human blood incorporating target DNA (hgDNA584) and control DNA (hgDNA528) at concentrations of 0.5, 1, and 50 ng μL–1. The variable adhesion forces of the tethered PNIPAAm brushes on the surfaces were used to capture and release DNA molecules through changes in temperature. After amplifying the signal of the hgDNA584 and hgDNA528 strands released from the tethered PNIPAAm on the substrate using the polymerase chain reaction (PCR), we identified these DNA macromolecules using agarose gel electrophoresis. The accuracy of the detection of hgDNA584 and hgDNA528 was controlled through the design of specific primers in the PCR process. The quantities of these two DNA molecules obtained through the capture and release from tethered PNIPAAm brushes under temperature tuning conditions were sufficient for them to be amplified recognizably, suggesting that this approach could be used in miniaturized lab-on-a-chip cartridges for rapid disease diagnosis.

Graphical abstractTethered poly(N-isopropylacrylamide) is synthesized to capture and release human genomic DNA by temperature tuning from a specimen including human blood and 0.5 ng L−1 concentration of target DNA..Figure optionsDownload full-size imageDownload high-quality image (56 K)Download as PowerPoint slideHighlights► Human genomic DNAs are captured by poly(N-isopropylacrylamide) brush. ► The quantity of DNA released from polymer brush is sufficient to diagnose breast cancer recurrence. ► Adhesion of poly(N-isopropylacrylamide) brush confirms the “tentacle” behavior.