Abstract

Bio- and Biomimetic Sensors for Medical Diagnostics Based on the Heat-Transfer Method

Patrick Wagner, Professor, Soft-Matter Physics and Biophysics Section, KU Leuven

In 2012, we found that the thermal denaturation of double-stranded DNA, immobilized on a sensor chip, goes along with a significant increase of the thermal boundary resistance at the solid-to-liquid interface. This effect can be utilized to detect SNP mutations as shown exemplarily on sequences of the PAH gene. The technique, now termed heat-transfer method HTM, has proven to be highly versatile in bioanalytical sensing: Using e.g. cell-imprinted polyurethane layers, we could detect and distinguish sharply between closely related cancer cell lines. Employing molecularly imprinted polymers (MIPs) as receptors, nicotine-, histamine-, and serotonin concentrations down to the nanomolar level could be measured. In combination with aptamer receptors, HTM can also serve for the detection of proteins such as the allergen Ara h1 in peanut-butter extract. So far, these thermal boundary effects are empirical, but latest results suggest that the mismatch between the characteristic vibration frequencies (solid, soft bio-molecular layer, liquid) may play a role. Conceptually, HTM is related to impedance spectroscopy in the sense that capacitive- or ionic currents are replaced by a thermal current. Potential advantages of HTM can be seen in the fact that this sensing principle is not limited to electrically conducting liquids and chip materials.