Spin coated chitin films for biosensors and its analysis are depended on chitin-surface interactions

Marco G. Casteleijn, Dominique Richardson, Petteri Parkkila, Niko Granqvist, Arto Urtti, Tapani Viitala

Research output: Contribution to journalArticleScientificpeer-review

10 Citations (Scopus)

Abstract

Chitin, abundant in nature, is a renewable resource with many possible applications in bioengineering. Biosensors, capable of label-free and in-line evaluation, play an important role in the investigation of chitin synthesis, degradation and interaction with other materials. This work presents a comparative study of the usefulness of a chitin surface preparation, either on gold (Au) or on polystyrene (PS). In both cases the most common method to dissolve chitin was used, followed by a simple spin-coating procedure. Multi-parametric surface plasmon resonance (MP-SPR), modeling of the optical properties of the chitin layers, scanning electron microscopy, and contact angle goniometry were used to confirm: the thickness of the layers in air and buffer, the refractive indices of the chitin layers in air and buffer, the hydrophobicity, the binding properties of the chitin binding domain (CBD) of Bacillus circulans, and the split-intein capture process. Binding of the CBD differed between chitin on Au versus chitin on PS in terms of binding strength and binding specificity due to a less homogenous structured chitin-surface on Au in comparison to chitin on PS, despite a similar thickness of both chitin layers in air and after running buffer over the surfaces. The use of the simple method to reproduce chitin films on a thin polystyrene layer to study chitin as a biosensor and for chitin binding studies was obvious from the SPR studies and the binding studies of CBD as moiety of chitinases or as protein fusion partner. In conclusion, stable chitin layers for SPR studies can be made from chitin in a solution of dimethylacetamide (DMA) and lithium chloride (LiCl) followed by spin-coating if the gold surface is protected with PS.
Original languageEnglish
Pages (from-to)261-272
Number of pages12
JournalColloids and Surfaces A: Physicochemical and Engineering Aspects
Volume539
DOIs
Publication statusPublished - 20 Feb 2018
MoE publication typeA1 Journal article-refereed

Keywords

  • biosensor
  • chitin
  • chitin binding domain
  • layer modeling
  • split-inteins
  • surface plasmon resonance (SPR)

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