Thin films of vitronectin transferred by MAPLE

We report on matrix-assisted pulsed laser evaporation (MAPLE) transfer of intact and functional protein molecules from a cryogenic aliquot obtained by freezing a protein-saline buffer solution. Vitronectin (Vn), an extracellular matrix protein with distinctive active domains for cell attachment and signalization, was expelled from frozen targets by KrF*excimer laser irradiation, and then immobilized on substrates. Particulates surrounded by a dense matrix were observed by optical, profilometry and AFM studies. The composition preservation of MAPLE-deposited protein films versus drop-cast films was demonstrated by FTIR and immunostaining studies. The stability and integrity of Vn after transfer was shown by their interaction with human osteoprogenitor cells in which actin filaments stretched across the entire cell area and clear focal points with surface were formed. The absence of detectable degradation of protein structure after MAPLE immobilization could provide benefits to surface functionalization for biomedical applications. © 2011 Springer-Verlag

Microstructure of hydroxyapatite thin layers grown by pulsed laser deposition

Thin films of hydroxyapatite (HAp) have been grown on Si, quartz, Ti, and Ge substrates by the pulsed laser deposition (PLD) method employing a KrF excimer laser (wavelength λ=248 nm, pulsed duration τFWHM= 20 ns). The influence of the laser deposition parameters on the properties of the grown layers was investigated in order to optimize the Ca/P ratio and the crystalline structure. It was found that the optimum conditions for preserving the Ca/P ratio i.e. high oxygen pressures and low substrate temperatures do not coincide with those for obtaining adherent and crystalline layers i.e. low oxygen pressures and high substrate temperatures. For films deposited onto Ti substrates it was also found that high substrate temperatures promote the diffusion of Ti through the depositing film up to the surface where it gets oxidized. Further investigations are required before high quality HAp-coated Ti implants by PLD can be obtained. ©2003 Copyright SPIE - The International Society for Optical Engineering