Switchable Release of Bone Morphogenetic Protein from Thermoresponsive Poly(NIPAM-co-DMAEMA)/Cellulose Sulfate Particle Coatings

Abstract

Thermoresponsive coatings of poly(N-isopropylacrylamide-co-DMAEMA)/cellulose sulfate (PNIPAM-DMAEMA/CS) complexes are reported eluting bone-morphogenetic-protein-2 (BMP-2) on demand relevant for implant assisted local bone healing. PNIPAM-DMAEMA/CS dispersions contained colloid particles with hydrodynamic radii RH = 170–288 nm at T = 25 °C shrinking to RH = 74–103 nm at T = 60 °C. Obviously, PNIPAM-DMAEMA/CS undergoes volume phase transition (VPT) analogously to pure PNIPAM, when critical VPT temperature (VPTT) is exceeded. Temperature dependent turbidity measurements revealed broad VPT and VPTT 47 °C for PNIPAM-DMAEMA/CS colloid dispersions at pH = 7.0. FTIR spectroscopy on thermoresponsive PNIPAM-DMAEMA/CS particle coatings at germanium model substrates under HEPES buffer indicated both wet-adhesiveness and VPT behavior based on diagnostic band intensity increases with temperature. From respective temperature courses empirical VPTT ≈ 42 °C for PNIPAM-DMAEMA/CS coatings at pH = 7.0 were found, which were comparable to VPTT found for respective dispersions. Finally, the PNIPAM-DMAEMA/CS coatings were loaded with BMP-2 and model protein papain (PAP). Time dependent FTIR spectroscopic measurements showed, that for T = 37 °C there was a relative protein release of ≈30% for PAP and ≈10% for BMP-2 after 24 h, which did not increase further. Heating to T = 42 °C for PAP and to 47 °C for BMP-2 further secondary protein release of ≈20% after 24 h was found, respectively, interesting for clinical applications. BMP-2 eluted even at 47 °C was found to be still biologically active.

Highly Efficient Antimicrobial and Antifouling Surface Coatings with Triclosan-Loaded Nanogels

“… 26 Additionally, the protonated DMAPMA amino segments are hydrophilic, leading to a stronger coordination of water molecules, and consequently, the VPTT is affected and the VPTT increase as compared to pure PNIPAM and the decrease in the hydrodynamic radius happen over a broader temperature range. 39 After quaternization with 1-bromo-dodecane, the thermoresponsiveness was altered compared to the N-nGel most likely because of the already collapsed network due to the intraparticle hydrophobic interactions of the dodecane chains that limit the swelling/deswelling process. As expected, the hydrophobic interactions and permanent charges affect the VPTT after quaternization, which additionally confirms that the modification with 1-bromo-dodecane is successful.…”

Thermoresponsive Catechol Based-Polyelectrolyte Complex Coatings for Controlled Release of Bortezomib

“…The necessary complexation was exploited to establish an external control of the release. Therefore, P(NIPAM- co -DMAEMA) (22 mole% DMAEMA) was used as the polycation, which is a thermoresponsive copolymer that exhibits a lower critical solution temperature (LCST) at 55 °C [21]. The coatings from the PECs were analyzed regarding their thermoresponsive properties using a self-manufactured heatable ATR-FTIR measurement cell.…”

Construction of biocompatible bilayered light‐driven actuator composed of rGO/PNIPAM and PEGDA hydrogel

“…To study the effect of reduction time on the photothermal conversion efficiency, GO/PNIPAM and rGO/PNIPAM hydrogels with different reduction times (24,48, and 72 hr) were prepared. When exposed to NIR laser, the surface temperature of GO/PNIPAM and rGO/PNIPAM hydrogels increased with time and then reached the equilibrium state (Figure 3c).…”

“…[21] Among these stimuli-responsive hydrogels, PNIPAM is one of the most widely studied temperature-responsive hydrogel with volume phase transition temperature (VPTT). [24] At the temperature below the VPTT (around 33 C), the side chains are linked with the water molecules by hydrogen bonds. PNIPAM is hydrophilic and swells in water.…”