Searching for a common origin of heat-transfer effects in bio- and chemosensors: A study on thiols as a model system

[Display omitted] •The heat-transfer method HTM is a thermal bio- and chemosensing technique that is applicable in a broad range of analytical applications.•Molecular-scale changes at the interface between a solid and a liquid can profoundly alter the heat-flow efficiency across the interface.•HTM allows monitoring the self-assembly kinetics of thiols at gold-ethanol interfaces in real time, simply by measuring with thermocouples.•The results suggest that heat transfer across interfaces takes place through inter-molecular exchange of vibrational energy.•Binding of targets to receptor-functionalized surfaces causes vibrational mismatch that is detectable at macroscopic length scales. The heat-transfer method HTM is a bioanalytical technique in which a temperature gradient is established between the backside of a functionalized chip and the supernatant liquid. By combining the measured temperature difference with the power used to generate this gradient, one obtains the thermal resistance Rth. This parameter responds sensitively and in a concentration-dependent way to the binding of bioparticles to receptors as well as to phase transitions in coatings on the chip. The size of particles that can be detected with HTM spans from low-molecular weight molecules over proteins and DNA fragments up to cells with diameters at the micron scale. In this work, we explore the question whether and why small ligands adsorption can result still in quantifiable Rth changes and whether there is a common origin of the generally observed Rth increase upon binding a wide variety of cells and biomolecules. The data obtained on thiols with different capping groups suggest that the correspondence of molecular vibration frequencies of the ligands and the liquid is decisive for an efficient or impeded heat transfer and hence for the macroscopically determined Rth parameter.