[Zurück]

A. Balbekova, G. Ramer, B. Lendl:
"Toward monitoring of dynamic biochemical systems by the time resolved photothermal infrared nanoscopy";
Poster: SCIX 2014, Reno, Nevada, US; 28.09.2014 - 03.10.2014; in: "Final Program Book of Abstracts", (2014), S. 143.

Over the past few years photothermal infrared (IR) nanoscopy attracted great scientific interest. Recently important advances with regard to spatial resolution and monolayer sensitivity were developed. However, so far, only static samples have been investigated. Our research activities are focused on the investigation of dynamic systems using photothermal IR nanoscopy. The working principle of this technique is based on the detection of the local thermal expansion of a sample induced by absorption of pulsed IR radiation. The sample expansion is recorded by an Atomic Force Microscope (AFM). The amplitude of a cantilever deflection is directly proportional to the sample's absorbance. Our experimental setup consists of the AFM (Agilent 5400 scanning probe microscope) coupled to an external cavity quantum cascade laser, EC-QCL (Daylight Solutions, California). The EC-QCL laser covers the wavelength region 1730-1565 1/cm. This spectral region is ideally suited for protein analysis. Poly-L-Lysine (PLL) has been selected as a model protein for our studies. PLL ultrathin films were spin-coated either on a calcium fluoride or on gold substrates. Experimental conditions were adjusted in order to perform a hydrogen-deuterium exchange and to achieve a transition from alpha-helix to beta-sheet secondary structure conformers through a temperature variation. Initial test measurements were performed using a Bruker IR microscope (Hyperion 3000). These experiments confirm the dynamic behavior of our model system. First data on using photothermal IR nanoscopy will be shown as well.