TY  - JOUR
A1  - Zhang, Nan
A1  - Said, Andre
A1  - Wischke, Christian
A1  - Kral, Vivian
A1  - Brodwolf, Robert
A1  - Volz, Pierre
A1  - Boreham, Alexander
A1  - Gerecke, Christian
A1  - Li, Wenzhong
A1  - Neffe, Axel T.
A1  - Kleuser, Burkhard
A1  - Alexiev, Ulrike
A1  - Lendlein, Andreas
A1  - Schäfer-Korting, Monika
T1  - Poly[acrylonitrile-co-(N-vinyl pyrrolidone)] nanoparticles - Composition-dependent skin penetration enhancement of a dye probe and biocompatibility
JF  - European Journal of Pharmaceutics and Biopharmaceutics
N2  - Nanoparticles can improve topical drug delivery: size, surface properties and flexibility of polymer nanoparticles are defining its interaction with the skin. Only few studies have explored skin penetration for one series of structurally related polymer particles with systematic alteration of material composition. Here, a series of rigid poly[acrylonitrile-co-(N-vinyl pyrrolidone)] model nanoparticles stably loaded with Nile Red or Rhodamin B, respectively, was comprehensively studied for biocompatibility and functionality. Surface properties were altered by varying the molar content of hydrophilic NVP from 0 to 24.1% and particle size ranged from 35 to 244 nm. Whereas irritancy and genotoxicity were not revealed, lipophilic and hydrophilic nanoparticles taken up by keratinocytes affected cell viability. Skin absorption of the particles into viable skin ex vivo was studied using Nile Red as fluorescent probe. Whilst an intact stratum corneum efficiently prevented penetration, almost complete removal of the horny layer allowed nanoparticles of smaller size and hydrophilic particles to penetrate into viable epidermis and dermis. Hence, systematic variations of nanoparticle properties allows gaining insights into critical criteria for biocompatibility and functionality of novel nanocarriers for topical drug delivery and risks associated with environmental exposure.
KW  - Biocompatibility testing
KW  - Drug delivery systems
KW  - Nanoparticle
KW  - Poly[acrylonitrile-co-(N-vinyl pyrrolidone)]
KW  - Polymers
KW  - Skin absorption
Y1  - 2017
U6  - https://doi.org/10.1016/j.ejpb.2016.10.019
SN  - 0939-6411
SN  - 1873-3441
VL  - 116
SP  - 66
EP  - 75
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Lendlein, Andreas
A1  - Heuchel, Matthias
T1  - Shape-memory polymers designed in view of thermomechanical energy storage and conversion systems
BT  - Effective temporary shape fixation by strain-induced formation of supramolecular nanostructures enables high energy density one-way shape-memory polymers
JF  - ACS central science
KW  - Actuators
KW  - Deformation
KW  - Energy
KW  - Energy storage
KW  - Polymers
Y1  - 2021
U6  - https://doi.org/10.1021/acscentsci.1c01032
SN  - 2374-7951
VL  - 7
IS  - 10
SP  - 1599
EP  - 1601
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Ghobadi, Ehsan
A1  - Heuchel, Matthias
A1  - Kratz, Karl
A1  - Lendlein, Andreas
T1  - Influence of different heating regimes on the shape-recovery behavior of poly(L-lactide) in simulated thermomechanical tests
JF  - Journal of applied biomaterials & functional materials
N2  - Aim: Multifunctional polymer-based biomaterials, which combine degradability with a shape-memory capability and in this way enable the design of actively moving implants such as self-anchoring implants or controlled release systems, have been recently introduced. Of particular interest are approved degradable polymers such as poly(L-lactide) (PLLA), which can be easily functionalized with a shape-memory effect. In the case of semicrystalline PLLA, the glass transition can be utilized as shape-memory switching domain.
 Methods: In this work we applied a fully atomistic molecular dynamics simulation to study the shape-memory behavior of PLLA. A heating-deformation-cooling programming procedure was applied to atomistic PLLA packing models followed by a recovery module under stress-free conditions allowing the shape recovery. The recovery was simulated by heating the samples from T-low = 250 K to T-high = 500 K with different heating rates beta of 125, 40 and 4 K.ns(-1).
 Results: We could demonstrate that the obtained strain recovery rate (R-r) was strongly influenced by the applied simulation time and heating rate, whereby R-r values in the range from 46% to 63% were achieved. On its own the application of a heating rate of 4 K.ns(-1) enabled us to determine a characteristic switching temperature of T-sw = 473 K for the modeled samples.
 Conclusions: We anticipate that the atomistic modeling approach presented should be capable of enabling further study of T-sw with respect to the molecular structure of the investigated SMP and therefore could be applied in the context of design and development of new shape-memory (bio) materials.
KW  - Molecular modeling
KW  - Polymers
KW  - Shape-memory effect
Y1  - 2012
U6  - https://doi.org/10.5301/JABFM.2012.10440
SN  - 2280-8000
VL  - 10
IS  - 3
SP  - 259
EP  - 264
PB  - Wichtig
CY  - Milano
ER  -