Polymeric Nanogels with Tailorable Degradation Behavior

Abstract

Please cite this article as: Schut IM, Engelhart D, Pasma JH, Aarts RGKM, Schouten A.C.Compliant support surfaces affect sensory reweighting during balance control.Gait and Posture http://dx.doi.org/10. 1016/j.gaitpost.2017.02.004 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Netherlands. Corresponding author:I.M.Schut, e-mail: i.m.schut@tudelft.nl Acknowledgements:This research is supported by the Dutch Technology Foundation STW (NeuroSIPE #10737 BalRoom) which is part of the Netherlands Organisation for Scientific Research (NWO), and which is partly funded by the Ministry of Economic Affairs. Declaration of conflicting interest:The authors whose names are listed above certify that they have NO affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers' bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or non-financial interest (such as personal or professional relationships, affiliations, knowledge or beliefs) in the subject matter or materials discussed in this manuscript.*I.M.Schut and D.Engelhart contributed equally to this work. 2 HighlightsStanding on foam yields a support surface rotation and a compliance effect on sensory reweighting.A support surface rotation effect leads to down weighting of proprioceptive information.A compliance effect leads to less sensory reweighting. 3 ABSTRACTTo maintain upright posture and prevent falling, balance control involves the complex interaction between nervous, muscular and sensory systems, such as sensory reweighting. When balance is impaired, compliant foam mats are used in training methods to improve balance control. However, the effect of the compliance of these foam mats on sensory reweighting remains unclear.In this study, eleven healthy subjects maintained standing balance with their eyes open while continuous support surface (SS) rotations disturbed the proprioception of the ankles. Multisine disturbance torques were applied in 9 trials; three levels of SS compliance, combined with three levels of desired SS rotation amplitude. Two trials were repeated with eyes closed. The corrective ankle torques, in response to the SS rotations, were assessed in frequency response functions (FRF). Lower frequency magnitudes (LFM) were calculated by averaging the FRF magnitudes in a lower frequency window, representative for sensory reweighting.Results showed that increasing the SS rotation amplitude leads to a decrease in LFM. In addition there was an interaction effec...

In Vitro Evaluation of Anti‐Aggregation and Degradation Behavior of PEGylated Polymeric Nanogels under In Vivo Like Conditions

“…N ‐(2‐hydroxyethyl)methacrylamide (HEMAm), HEMAm‐oligoglycolates (HEMAm‐Gly, degree of polymerization 1.83), and N ‐(2‐azidoethyl)methacrylamide (AzEMAm) were synthesized as previously described . BCN‐PEG 5000 ‐OMe was purchased from SynAffix BV (Oss, the Netherlands).…”

“…P(HEMAm‐co‐AzEMAm)‐Gly‐HEMAm with degrees of substitution (DS, the number of methacryloyl groups per 100 HEMAm units) of ≈5, 10, and 20 were prepared as previously described . Briefly, 1,1′‐carbonyldiimidazole (CDI)‐activated HEMAm‐Gly (HEMAm‐Gly‐CI) was obtained by reaction of the hydroxyl group of HEMAm‐Gly (degree of polymerization 1.83) with CDI.…”

“…A common method is to measure their weight loss during incubation . Determination of changes in particle size as well as particle concentration in the suspension has also been investigated . Assaying the degradation products is another way to study the degradation kinetics of nanoparticles .…”

“…Determination of changes in particle size as well as particle concentration in the suspension has also been investigated . Assaying the degradation products is another way to study the degradation kinetics of nanoparticles . However, while these techniques can provide important information about the physicochemical characteristics of the material used, they have limited predictive value for their in vivo performance as nanocarrier drug formulations.…”

“…Moreover, by varying the chemical composition of nanogels, their characteristics such as size, charge, porosity, amphiphilicity, softness, and degradability can be fine‐tuned and tailored. Our previous study has shown that pHEMAm‐Gly‐HEMAm nanogels are cytocompatible and their degradation can be tailored depending on the crosslink density of nanogels . Therefore, PEGylated biodegradable p(HEMAm‐co‐AzEMAm)‐Gly‐HEMAm‐based nanogels that require in vitro optimization of their degree of PEGylation and crosslink density ( Figures 1 and 2 ) were used as an example.…”