University of Oulu

Simo Kalliola, Eveliina Repo, Varsha Srivastava, Juha P. Heiskanen, Juho Antti Sirviö, Henrikki Liimatainen, Mika Sillanpää, The pH sensitive properties of carboxymethyl chitosan nanoparticles cross-linked with calcium ions, Colloids and Surfaces B: Biointerfaces, Volume 153, 1 May 2017, Pages 229-236, ISSN 0927-7765,

The pH sensitive properties of carboxymethyl chitosan nanoparticles cross-linked with calcium ions

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Author: Kalliola, Simo1; Repo, Eveliina1; Srivastava, Varsha1;
Organizations: 1Lappeenranta University of Technology, Sammonkatu 12, Mikkeli FI-50130, Finland
2Research Unit of Sustainable Chemistry, University of Oulu, P.O. Box 3000, FI-90014, Finland
3Fibre and Particle Engineering Research Unit, University of Oulu, P.O. Box 4300, FI-90014, Finland
4Department of Civil and Environmental Engineering, Florida International University, Miami, FL-33174, USA
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.5 MB)
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Language: English
Published: Elsevier, 2017
Publish Date: 2017-03-01


In environmental applications the applied materials are required to be non-toxic and biodegradable. Carboxymethyl chitosan nanoparticles cross-linked with Ca²⁺ ions (CMC-Ca) fulfill these requirements, and they are also renewable. These nanoparticles were applied to oil-spill treatment in our previous study and here we focused on enhancing their properties. It was found that while the divalent Ca²⁺ ions are crucial for the formation of the CMC-Ca, the attractive interaction between -NH₃⁺ and -COO⁻ groups contributed significantly to the formation and stability of the CMC-Ca. The stability decreased as a function of pH due to the deprotonation of the amino groups. Therefore, the nanoparticles were found to be fundamentally pH sensitive in solution, if the pH deviated from the pH (7–9) that was used in the synthesis of the nanoparticles. The pH sensitive CMC-Ca synthesized in pH 7 and 8 were most stable in the studied conditions and could find applications in oil-spill treatment or controlled-release of substances.

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Series: Colloids and surfaces. B, Biointerfaces
ISSN: 0927-7765
ISSN-E: 1873-4367
ISSN-L: 0927-7765
Volume: 153
Pages: 229 - 236
DOI: 10.1016/j.colsurfb.2017.02.025
Type of Publication: A1 Journal article – refereed
Field of Science: 116 Chemical sciences
215 Chemical engineering
Funding: This study was funded by the Academy of Finland (decision number 283200).
Academy of Finland Grant Number: 283200
Detailed Information: 283200 (Academy of Finland Funding decision)
Dataset Reference: Supplementary data associated with this article can be found, in the online version, at
Copyright information: © 2017 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (