Preparation of Monomodal Polyelectrolyte Complex Nanoparticles of PDADMAC/Poly(Maleic Acid-alt-α-methylstyrene) by Consecutive Centrifugation

Abstract

We report on the refinement of anionic and cationic nanoparticles of nonstoichometric polyelectrolyte complexes (PEC) by consecutive centrifugation, which was studied by dynamic light scattering (DLS), atomic force microscopy (AFM), colloid titration and infrared spectroscopy (IR). PEC dispersions were prepared by mixing poly(diallyldimethylammonium chloride) (PDADMAC) and sodium poly(maleic acid-alt-alpha-methylstyrene) (PMA-MS) at the monomolar mixing ratio of n-/n+ = 1.50 (anionic PEC) and 0.66 (cationic PEC), respectively, and the polymer concentration of c(POL) = 0.002 M. The particle size (Rh), titrable charge amount, and IR spectra were determined for both dispersions in the original state, after the first centrifugation and after the second centrifugation. Freshly prepared PEC dispersions contained two different particle sizes: around 10-25 nm (small particles) and around 100 nm (large particles). Consecutive centrifugation of freshly prepared PEC dispersions resulted in the separation of highly charged excess polyelectrolyte (PEL) and small PEC particles from a low charged coacervate phase of the desired larger PEC particles. After the second centrifugation, the coacervate phase of both dispersions PEC-1.50 and PEC-0.66 consisted of monomodal particles sizing around 100 nm. These results were supported by AFM measurements on the respective dispersions deposited on glass plates. PEC-1.50 particles tended to adopt slightly smaller sizes ( approximately 90 nm) in comparison to PEC-0.66 ones (approximately 110 nm). No significant influence of the PDADMAC molecular weight on the particle size was found. IR spectroscopy showed changes in the environment of the carboxylate groups of PMA-MS by consecutive centrifugation. The centrifuged PEC-1.50 dispersions showed remarkable long-term stability over more than a year. The high macroscopic stability of the studied PEC dispersions is presumably due to repulsive electrostatic interparticle interactions and attractive hydrophobic intraparticle interaction. The introduced monomodal PEC particles might be projected as latex analogues or as nanocarriers for drugs and proteins.

Cast adhesive polyelectrolyte complex particle films of unmodified or maltose-modified poly(ethyleneimine) and cellulose sulphate: fabrication, film stability and retarded release of zoledronate

“…The hydrodynamic radius R H was estimated using the Stokes-Einstein equation. Intensity weighted DLS data were considered, as it was applied earlier therein [18]. Errors of R H are related to the standard deviation of at least three different measurements.…”

Interaction between immobilized polyelectrolyte complex nanoparticles and human mesenchymal stromal cells

“…Intensity-weighted DLS data were considered, as they were applied earlier therein. 26 Errors of D H are related to the standard deviation of at least three different sample measurements. The Zetasizer 3000 Software (PCS v.1.61 Rev 1) of Malvern Instruments Ltd was used for recording and calculating DLS parameters.…”

Polyelectrolyte Complex Nanoparticles of Poly(ethyleneimine) and Poly(acrylic acid): Preparation and Applications

“…In typical PEC systems standard cationic and anionic PELs and PELs of natural origin like polypeptides, polysaccharides and their modified analogues are combined. Beside PEL structural parameters, important parameters were found to be the molar mixing ratio of charged units (n − /n + ), concentration, pH and ionic strength, which can regulate particle size, distribution and shape [11,12] and the interaction to surfaces [13][14][15][16]. Dynamic light scattering (DLS) and colloid titration were applied on the dispersions as well as scanning force microscopy (SFM) and attenutaed total reflection (ATR) Fourier transform infrared (FTIR) spectroscopy on particle layers.…”

“…Dynamic light scattering (DLS) and colloid titration were applied on the dispersions as well as scanning force microscopy (SFM) and attenutaed total reflection (ATR) Fourier transform infrared (FTIR) spectroscopy on particle layers. Recently, the monomodality of PEC dispersions could be significantly improved applying consecutive centrifugation, separation and redispersion steps of the coacervate phase, which was explained by -accelerated ripening‖ (Ostwald) of the raw dispersion [12]. This experimental finding was proved by recent simulation studies [17] supporting, that the PEC formation process is subdivided in the rapid formation of molecular or primary complex particles (R H = 5-20 nm), which is followed by aggregation of primary particles to secondary particles.…”