Liquid phase SPR imaging experiments for biosensors applications

Surface plasmon resonance (SPR) has recently gained attention as a label-free method for the detection of biological molecules binding onto functionalised surfaces. It is one of the most sensitive detection method for monitor variations in the thickness and refractive index in ultra-thin films. Here, the adsorption processes of oligonucleotides onto gold substrates have been investigated in aqueous buffer solution using SPR imaging measurements. The hybridization of a thiol-modified, single stranded oligonucleotide anchored to a gold surface via thiol group, with its complementary sequence has been observed and characterised monitoring the hybridization process by SPR equipment. In situ investigation of smallest changes in SPR imaging measurements dynamically performed in liquid phase in the presence of DNA complementary probes was performed. Infrared spectroscopy and scanning electron microscopy characterisation of the functionalised gold surfaces of the biosensor were compared with the images obtained by SPR experimental apparatus.     

Purification and properties of a thermophilic and thermostable DNA polymerase from the archaebacterium Sulfolobus solfataricus

A DNA-dependent DNA polymerase was obtained in homogenous form from the thermoacidophilic archaebacterium Sulfolobus solfataricus. The enzyme, purified 706-fold, has a molecular mass of about 110000 daltons as determined by gel filtration and by glycerol gradient centrifugation. It requires Mg++ for its activity and has a pH optimum of 7.7. The activity is sharply dependent on the ionic strength. The enzyme is thermostable; its properties and activity requirements were characterized. The features of this enzyme are compared to those of other DNA polymerases isolated either from prokaryotes or eukaryotes.