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X. J. Dai, J. du Plessis, I. L. Kyratzis, G. Maurdev, M. G. Huson, C. Coombs, Plasma Process. Polym. 2009, 6, 490
L. Li, X. J. Dai,* H. S. Xu, J. H. Zhao, P. Yang, G. Maurdev, J. du Plessis, P. R. Lamb, B. L. Fox, and W. P. Michalski, Plasma Process. Polym. 2009, DOI: 10.1002/ppap.20090004
Two key steps towards improved bio-interfaces have been demonstrated. Primary amines (-NH2) are an important functional group for bonding biological molecules. The first paper demonstrates that the density of primary amines on a degradable polymer can be controlled by selection of pulsed plasma conditions. The NH2 groups come from the plasma polymerization of heptylamine (PPHA) with the amount being quantified by chemical derivatization. The treatment gave increased hydrophilicity and achieved a sufficient level of primary amine functionality (3.5%) for practical applications. The duty cycle and the average RF power were the key parameters for achieving both a higher density of primary amines and increased hydrophilicity.
The second paper reveals the novel approach of combining continuous wave (CW) and pulsed plasma modes. This has enabled the generation of stable interfaces with a higher density of -NH2 on metals, ceramics and semiconductors. In this new design, a thin CW PPHA layer provides strong cross-linking and attachment to the metal or semiconductor surface and a good foundation for better bonding of a pulsed PPHA layer. This top layer has higher levels of functional groups because it retains more of the monomer structure. The combined mode provides the pulsed mode advantage of a 3-fold higher density of -NH2 while retaining much of the markedly higher stability in aqueous solutions, or during sterilization, of the continuous mode.
Gianni Ciofani1,*, Vittoria Raffa1, Jun Yu2, Ying Chen2, Yosuke Obata3, Shinji Takeoka3, Arianna Menciassi1,4, and Alfred Cuschieri
1Scuola Superiore Sant'Anna, Piazza Martiri della LibertÓ, 33 - 56127 Pisa, Italy
2Department of Electronic Materials and Engineering, Research School of Physical Sciences and Engineering, The Australian National University, Canberra, ACT 0200, Australia
3Department of Life Science and Medical Bioscience, School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsu- cho, Shinjuku-ku, Tokyo 162-8480, Japan
4Italian Institute of Technology (IIT), Via Morego, 30 - 16163 Genova, Italy
Current Nanoscience, 2009, 5, 33-38
Abstract: Whereas several biomedical applications of carbon nanotubes have been proposed, the use of boron nitride nanotubes (BNNTs) in this field has been largely unexplored despite their unique and potentially useful properties. Our group has recently initiated an experimental program aimed at the exploration of the interactions between BNNTs and living cells. In the present paper, we report on the magnetic properties of BNNTs containing Fe catalysts which confirm the feasibility for their use as nanovectors for targeted drug delivery. The magnetisation curves of BNNTs characterised by the present study are typical of superparamagnetic materials with important parameters, including magnetic permeability and magnetic momentum, derived by employing Langevin theory. In-vitro tests have demonstrated the feasibility for influencing the uptake of BNNTs by living cells by exposure to an external magnetic source. A finite element method analysis devised to predict this effect produced predictive data with close agreement with the experimental observations.
Magnetic driven BNNT uptake: experimental set-up and main result.
J. Yu, Y. Chen, B.M. Cheng
Solid State Communications 149 (2009) 763 - 766
Abstract: Ammonium oleate surfactants can help the dispersion of multiwalled boron nitride nanotubes (BNNTs) in water to form a BNNT solution stable for several months, which was due to the non-covalent functionalization of nanotube surfaces. Fourier Transform Infrared Spectroscopy (FTIR) and Photoluminescence (PL) analysis with synchrotron radiation source revealed that this BNNT aqueous solution preserves the intrinsic optical properties of BNNTs.
Photos of the BNNT solutions suspended for different times: (a) 8 days, (b) 11 days, (c) 14 days, and (d) 60 days.