Study of in situ adsorption kinetics of polyelectrolytes and liposomes using quartz crystal microbalance: Influence of experimental layout

A. A. Duarte, L. M G Abegão, J. H F Ribeiro, J. P. Lourenço, P. A. Ribeiro, M. Raposo

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Quartz Crystal Microbalance (QCM) is a widely used technique to characterize adsorption/desorption phenomena at the solid/liquid interface. However, the obtained adsorption/desorption kinetics curves are often not reproducible and present some noise and long term fluctuations. In this work, the accuracy of a commercial QCM to measure the adsorbed amount of polyelectrolytes and biological molecules was evaluated in terms of experimental QCM configurations with respect to quality, stability, and reproducibility of the measured data. Evaluation consisted in comparing the adsorption kinetics curves of the cationic polyelectrolyte poly(ethyleneimine) and the anionic 1,2-dipalmitoyl-sn-glycero-3-phospho-(1′-rac-glycerol) (sodium salt) liposomes, when setting the quartz crystal surface in stationary horizontal open, stationary horizontal closed, stationary vertical open, continuous vertical closed, and stationary vertical closed measuring configuration. For this last configuration, a new cell was designed and implemented. The analysis of the kinetics curves revealed that horizontal modes are more unstable when subjected to fostering noise due to the mechanical vibrations and lead to resonance frequency shift. This shift is caused by the measurement of non-adsorbed molecules which are deposited on the quartz crystal due to gravity force. The vertical modes proved to be more reproducible and reliable.

Original languageEnglish
Article number063901
JournalReview of Scientific Instruments
Volume86
Issue number6
DOIs
Publication statusPublished - 1 Jun 2015

Keywords

  • BY-LAYER FILMS
  • QCM-D
  • SURFACE
  • SENDOR
  • WATER
  • MICROSCOPY
  • MEMBRANES
  • POLYMER
  • BINDING
  • CELLS

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