PMID- 16800688
OWN - NLM
STAT- MEDLINE
DCOM- 20070803
LR  - 20081121
IS  - 0743-7463 (Print)
IS  - 0743-7463 (Linking)
VI  - 22
IP  - 14
DP  - 2006 Jul 4
TI  - Selective protein adsorption on a phase-separated solvent-cast polymer blend.
PG  - 6286-92
AB  - Polymer-based biomedical devices are growing increasingly sophisticated as 
      compositions evolve toward copolymers and blends in order to satisfy complex 
      design criteria. Such polymers afford opportunities for both micro- and 
      macrophase separation at nano- and micro-length scales and raise questions 
      concerning the role of heterogeneous surface morphology on protein adsorption. 
      Adsorbed protein layers play a critical role in mediating the interaction of 
      cells with polymer surfaces, and both understanding and controlling protein 
      adsorption is assuming greater significance in the development of surfaces with 
      enhanced physiological compatibility. Here we study the short-time adsorption of 
      ferritin, a model protein highly resistant to denaturation and easily imaged in 
      the transmission electron microscope (TEM), onto a phase-separated homopolymer 
      blend of polycaprolactone (PCL) and a polycarbonate derived from 
      desaminotyrosyl-tyrosine dodecyl ester (PDTD). At physiological pH, ferritin 
      selectively adsorbs onto the PDTD phase at a surface density approximately three 
      times greater than that on the PCL phase. By decreasing the pH below ferritin's 
      isoelectric point so its average charge becomes positive, the selective 
      adsorption disappears and the surface density of adsorbed ferritin becomes 
      independent of the phase separation. We attribute the selectivity to the 
      electrostatic repulsion between ferritin and hydrolytically charged PCL, both of 
      which will have a net negative charge at physiological pH. To perform these 
      experiments, we solvent-cast ultrathin polymer films onto dissolvable salt 
      substrates, and we characterize the morphology by TEM imaging and quantitative 
      spatially resolved electron energy-loss spectroscopy (EELS). We find that the 
      film morphology depends strongly on such processing-related variables as the 
      solvent evaporation rate and the nature of the surface in contact with the 
      polymer film during casting. The adsorption of ferritin depends on whether the 
      film is phase-separated as well as to which surface of the film the protein 
      solution is exposed, and these findings suggest that seemingly small variations 
      in polymer processing that influence both the bulk and surface morphology can 
      have a profound effect on the short-time protein adsorption.
FAU - Sousa, Alioscka
AU  - Sousa A
AD  - Department of Chemical, Biomedical, and Materials Engineering, Stevens Institute 
      of Technology, Hoboken, New Jersey 07030, USA.
FAU - Sengonul, Merih
AU  - Sengonul M
FAU - Latour, Robert
AU  - Latour R
FAU - Kohn, Joachim
AU  - Kohn J
FAU - Libera, Matthew
AU  - Libera M
LA  - eng
GR  - PH1 EB001046-01A1/EB/NIBIB NIH HHS/United States
PT  - Journal Article
PT  - Research Support, N.I.H., Extramural
PT  - Research Support, U.S. Gov't, Non-P.H.S.
PL  - United States
TA  - Langmuir
JT  - Langmuir : the ACS journal of surfaces and colloids
JID - 9882736
RN  - 0 (Polycarboxylate Cement)
RN  - 0 (Polyesters)
RN  - 0 (Solvents)
RN  - 24980-41-4 (polycaprolactone)
RN  - 25766-59-0 (polycarbonate)
RN  - 9007-73-2 (Ferritins)
SB  - IM
MH  - Adsorption
MH  - Animals
MH  - Ferritins/*chemistry
MH  - Horses
MH  - Hydrogen-Ion Concentration
MH  - Phase Transition
MH  - Polycarboxylate Cement/*chemistry
MH  - Polyesters/*chemistry
MH  - Solvents/chemistry
MH  - Spectroscopy, Electron Energy-Loss
MH  - Static Electricity
EDAT- 2006/06/28 09:00
MHDA- 2007/08/04 09:00
CRDT- 2006/06/28 09:00
PHST- 2006/06/28 09:00 [pubmed]
PHST- 2007/08/04 09:00 [medline]
PHST- 2006/06/28 09:00 [entrez]
AID - 10.1021/la053081r [doi]
PST - ppublish
SO  - Langmuir. 2006 Jul 4;22(14):6286-92. doi: 10.1021/la053081r.