Biosensing of dissolved analytes with AFM based single molecule force spectroscopy

Atomic force microscopy based single molecule force spectroscopy is an important tool for directly investigating the interactions between synthetically engineered biomolecules and different materials interfaces. Based on this technique, biosensors for the detection of adenosine, mercury ions, and thrombin are developed in the thesis. The biosensors based on specific aptamers for the detection of adenosine and mercury ions show extremely high sensitivity and selectivity. A novel method based on single molecule force mapping method is also developed and applied for the detection of mercury ions. The method is simple, quick, and also shows excellent sensitivity and selectivity. In addition, the interactions of avidin biotin and streptavdin biotin are investigated by single molecule force spectroscopy in combination with a specific oligopeptide sequence, with the aim to detecting thrombin in aqueous solution. This system and the underlying sensing principle are relatively complex, so more efforts are needed to improve this biosensora s performance. In summary, it is believed the AFM based single molecule force spectroscopy sensing technique developed in the present thesis will be useful and promising also for many other analytes. It has the potential to be exploited in commercial devices especially because of the low detection limit, if a sufficient degree of automatization and reproducibility are achieved.