TY - JOUR
T1 - Nanomechanical properties of multi-block copolymer microspheres for drug delivery applications
AU - Moshtagh, PR
AU - Rauker, J
AU - Sandker, Marjan
AU - Zuiddam, MR
AU - Dirne, FWA
AU - Klijnstra, E
AU - Duque, L
AU - Steendam, R
AU - Weinans, H
AU - Zadpoor, AA
PY - 2014
Y1 - 2014
N2 - Biodegradable polymeric microspheres are interesting drug delivery vehicles for site-specific sustained release of drugs used in treatment of osteoarthritis. We study the nano-mechanical properties of microspheres composed of hydrophilic multi-block copolymers, because the release profile of the microspheres may be dependent on the mechanical interactions between the host tissues and the microspheres that aim to incorporate between the cartilage surfaces. Three different sizes of monodisperse microspheres, namely 5, 15, and 30 van, were tested in both dry and hydrated (swollen) states. Atomic force microscopy was used for measuring nanoindentation-based force-displacement curves that were later used for calculating the Young's moduli using the Hertz's contact theory. For every microsphere size and condition, the measurements were repeated 400-500 times at different surface locations and the histograms of the Young's modulus were plotted. The mean Young's modulus of 5, 15, and 30 mu m microspheres were respectively 56.1 +/- 71.1 (mean +/- SD), 94.6 +/- 103.4, and 57.6 +/- 58.6 MPa under dry conditions and 226.4 +/- 54.2, 334.5 +/- 128.7, and 342.5 +/- 136.8 kPa in the swollen state. The histograms were not represented well by the average Young's modulus and showed three distinct peaks in the dry state and one distinct peak in the swollen state. The peaks under dry conditions are associated with the different parts of the co-polymeric material at the nano-scale. The measured mechanical properties of swollen microspheres are within the range of the nano-scale properties of cartilage, which could favor integration of the microspheres with the host tissue. (C) 2014 Elsevier Ltd. All rights reserved.
AB - Biodegradable polymeric microspheres are interesting drug delivery vehicles for site-specific sustained release of drugs used in treatment of osteoarthritis. We study the nano-mechanical properties of microspheres composed of hydrophilic multi-block copolymers, because the release profile of the microspheres may be dependent on the mechanical interactions between the host tissues and the microspheres that aim to incorporate between the cartilage surfaces. Three different sizes of monodisperse microspheres, namely 5, 15, and 30 van, were tested in both dry and hydrated (swollen) states. Atomic force microscopy was used for measuring nanoindentation-based force-displacement curves that were later used for calculating the Young's moduli using the Hertz's contact theory. For every microsphere size and condition, the measurements were repeated 400-500 times at different surface locations and the histograms of the Young's modulus were plotted. The mean Young's modulus of 5, 15, and 30 mu m microspheres were respectively 56.1 +/- 71.1 (mean +/- SD), 94.6 +/- 103.4, and 57.6 +/- 58.6 MPa under dry conditions and 226.4 +/- 54.2, 334.5 +/- 128.7, and 342.5 +/- 136.8 kPa in the swollen state. The histograms were not represented well by the average Young's modulus and showed three distinct peaks in the dry state and one distinct peak in the swollen state. The peaks under dry conditions are associated with the different parts of the co-polymeric material at the nano-scale. The measured mechanical properties of swollen microspheres are within the range of the nano-scale properties of cartilage, which could favor integration of the microspheres with the host tissue. (C) 2014 Elsevier Ltd. All rights reserved.
U2 - 10.1016/j.jmbbm.2014.03.002
DO - 10.1016/j.jmbbm.2014.03.002
M3 - Article
C2 - 24704968
SN - 1751-6161
VL - 34
SP - 313
EP - 319
JO - Journal of the Mechanical Behavior of Biomedical Materials
JF - Journal of the Mechanical Behavior of Biomedical Materials
ER -