Chemical and Structural Properties of Drug–protein Nanocomposites Prepared by Pulsed Laser Deposition from Conjugated Targets

Abstract

Nanostructured indomethacin (IM) – bovine serum albumin (BSA) composite particulates below 50 nm were obtained by pulsed laser deposition (PLD) with 1064 nm IR beam. IM and BSA powders were coground for up to 210 min to prepare conjugated targets for PLD with varying structural states. The ablation threshold was determined to be around 1.8 J/cm², from in situ monitoring of the deposited amount by a QCM sensor. The crystallinity of IM was preserved after PLD at 5 J/cm² and decreased with increasing the laser fluence. The non-crystalline state of IM in the target after prolonged cogrinding with BSA, was also preserved in the deposited film. FT-IR absorption bands due to amide I of BSA became sharper while preserving the peak top position after cogrinding with IM. Conversely, we observed broadening of the amide I bands by PLD. Preservation and change in the chemical and structural states of the conjugates after PLD is discussed in terms of the secondary structure of BSA and crystallinity of IM.