Multiplexed DNA Biomarker Detection with Phase Change Nanoparticles
This talk describes a multiplexed highly-sensitive technique to detect miRNA biomarkers using solid-to-liquid phase change nanoparticles. The nanoparticles of metals and eutectic alloys with sharp melting peaks will be modified with single strand DNAs (ssDNAs), which specifically bind to one end of miRNA biomarkers. A panel of nanoparticles with composition-dependent melting temperatures will be utilized to detect multiple biomarkers after establishing a one-to-one correspondence between one type of nanoparticle and one type of biomarker. An aluminum substrate with high thermal conductivity will be modified with a panel of ssDNAs that are complementary to the other ends of miRNA biomarkers. The detection scheme is that: (1) the receptor-modified nanoparticles will be incubated in a buffer containing biomarkers; (2) after centrifugation to remove unbound species in blood, biomarkers attached on nanoparticles will be re-suspended in another buffer; (3) the substrate will be immersed in the buffer to catch nanoparticles by forming DNA-RNA duplex; (4) the substrate will be washed to remove excess nanoparticles, and the attached nanoparticles will be readout with differential scanning calorimetry (DSC), where the temperature and area of melting peak reflect the presence and amount of biomarker.
Ten different metals that can form binary eutectic alloys among any two of them are identified. They can form 1,023 types of metallic and eutectic alloy nanoparticles. The compositions and melting temperatures of high order eutectic alloys are determined by calculation of phase diagram. Based on the eutectic compositions, nanoparticles are made by thermally decomposing organometallic precursors in a high boiling point solvent (ethylene glycol) using polyvinyl alcohol as surfactant. The nanoparticles and the aluminum substrate are modified with thiolated probe ssDNA and capture ssDNA, respectively. The lowest target concentration that can be detected is 80 pM. Further, the thermal ramp rates are remained constant to readout indium nanoparticles, but are changed from 1 to 10 °C/min to readout bismuth nanoparticles. The variable ramp rate in the same scan allows ten time adjustment of heat flux (sensitivity). Four different miRNAs are simultaneously detected with four types of nanoparticles, tin, tin-lead alloy, indium and bismuth.