Analysis of Interpenetrating Polymer Networks via Quartz Crystal Microbalance with Dissipation Monitoring

Abstract

A quartz crystal microbalance with dissipation monitoring (QCM-D) was used to assess the physical properties of interpenetrating polymer networks (IPNs) through swelling experiments in ambient humidity and in phosphate-buffered saline (PBS), pH 7.4. The IPNs, based on acrylamide (AAm) and poly(ethylene glycol) (pEG), swell from thin, rigid films when dry (16.7 +/- 5.2 nm on Si/SiO(2)) to expanded, viscoelastic films when hydrated (107 +/- 24.2 nm on Si/SiO2). The dry IPNs could be analyzed using the Sauerbrey relationship, but for the hydrated films it was necessary to interpret QCM-D data with a Kelvin-Voigt viscoelastic model. A complex modulus |G| of 116 +/- 38.1 kPa for the swollen IPN surface on Si/SiO2 was defined by the model. The QCM-D was also employed to quantify the adsorption of human fibrinogen, a protein important in thrombus formation, onto the IPNs. Fibrinogen adsorption studies demonstrated the sensitivity of the QCM-D, as well as confirmed the nonfouling nature of the IPN surface, where less than 5 ng/cm2 of fibrinogen was adsorbed.

Characterization of Matrigel interfaces during defined human embryonic stem cell culture

“…20 Briefly, alternating current is applied to the piezoelectric quartz crystal so that it oscillates in a shear mode at its resonant frequency. Only negative overtones can be excited electrically, and in the Q-sense system, the first, third, fifth, seventh, ninth, eleventh, and thirteen overtones ͑designated as F1, F3, F5, F7, F9, F11, and F13, respectively͒ are excited sequentially by applying the associated voltage.…”

“…In this experiment F1 and D1 were ignored as they were not reliable. 20,21 Frequency and dissipation values were recorded in air for all crystals. All liquids were allowed to reach room temperature before introduction into the QCM-D chamber, which was set to 25°C.…”

Biomimetic interfacial interpenetrating polymer networks control neural stem cell behavior

“…17 Briefly, sensor crystals were coated with 200 nm of silicon/silicon dioxide (Si/SiO 2 ), and an unsaturated organosilane, ATC, was grafted onto the crystals by soaking them in a 1.25% (v/v) solution of ATC in anhydrous toluene (prepared in a nitrogen glovebox) for 5 min. The sensor crystals were baked for 30 min at 1258C, and the IPN synthesis of p(AAm-co-EG/AAc) proceeded as described above.…”

“…18 X-ray photoelectron spectra (XPS) were recorded using a PHI 5400 instrument (Physical Electronics, Chanhassen, MN), with a nonmonochromatic Mg anode as the X-ray source at a takeoff angle of 558, using the same method as described elsewhere. 16,17 Neural stem cell culture Neural stem cells were isolated from the hippocampi of adult female Fischer 344 rats as previously described. 8 Cells (600-30,000 cells/cm 2 ) were seeded onto peptide-modified and laminin-modified culture wells and incubated (378C, 5% CO 2 ) in serum-free media consisting of DMEM/Hams F-12 medium with N-2 supplement.…”

Peri‐implant bone formation and implant integration strength of peptide‐modified p(AAM‐co‐EG/AAC) interpenetrating polymer network‐coated titanium implants

“…In its unmodified form, the p(AAm-co-EG) IPN prevented protein adsorption in complex serum-containing environments in vitro. 29,31 For in vivo applications, a significant benefit of p(AAm-co-EG) IPN is that it is also composed of nonfouling PEG chains within the network, which add redundancy to the system to ensure that protein adsorption is retarded. By not relying on a single grafted layer (i.e., PEG brush or self-assembled monolayer), the system is more robust.…”