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Chitosan is an important and abundant natural-based polymer, and it has broad applications. However, dissolving chitosan in plain water is a challenge, which mostly limits the biomedical applications of chitosan materials. Herein, we report an ecofriendly dissolution method to obtain a plain water-based chitosan solution for the first time. In this method, dissolving chitosan in ionic liquid followed by overnight freezing at −20 °C and subsequent solvent exchange with plain water at room temperature results in a stable chitosan dispersion in water with nanosize, namely water-based, chitosan pseudosolution. The overall process is ecofriendly. This new method augments the quality and processability of chitosan solutions used in manufacturing and bioprocessing and promotes the biomedical applications of chitosan-based products.

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BackgroundPrecise spatial control and patterning of cells is an important area of research with numerous applications in tissue engineering, as well as advancing an understanding of fundamental cellular processes. Poly (dimethyl siloxane) (PDMS) has long been used as a flexible, biocompatible substrate for cell culture with tunable mechanical characteristics. However, fabrication of suitable physico-chemical barriers for cells on PDMS substrates over large areas is still a challenge.ResultsHere, we present an improved technique which integrates photolithography and cell culture on PDMS substrates wherein the barriers to cell adhesion are formed using the photo-activated graft polymerization of polyethylene glycol diacrylate (PEG-DA). PDMS substrates with varying stiffness were prepared by varying the base to crosslinker ratio from 5:1 to 20:1. All substrates show controlled cell attachment confined to fibronectin coated PDMS microchannels with a resistance to non-specific adhesion provided by the covalently immobilized, hydrophilic PEG-DA.ConclusionsUsing photolithography, it is possible to form patterns of high resolution stable at 37°C over 2 weeks, and microstructural complexity over large areas of a few cm2. As a robust and scalable patterning method, this technique showing homogenous and stable cell adhesion and growth over macroscales can bring microfabrication a step closer to mass production for biomedical applications.Electronic supplementary materialThe online version of this article (doi:10.1186/1754-1611-8-24) contains supplementary material, which is available to authorized users.