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Chromogenic silk films - application to pH and glucose detection

Toytziaridis, Andreas LU (2016) KBK820 20161
Pure and Applied Biochemistry
Abstract
Five consecutive experiments were conducted with the goal to produce a chromogenic silk film, namely a film that is optically responsive to pH and glucose, made of regenerated silk fibroin, laponite, organic dye and glucose oxidase enzyme. The goal also included that the film should be produced with simple methods, such as adsorption and mixing in water. 2 dyes well suited for adsorbing onto laponite while still retaining pH responsive, Neutral red and Thionine acetate, were selected in a screening by UV-vis spectrophotometry and spectrofluorimetry. A factorial design experiment was conducted to optimize the ratios of silk, laponite and dye for greatest response in absorbance and fluorescence. New films of the chosen recipe, containing... (More)
Five consecutive experiments were conducted with the goal to produce a chromogenic silk film, namely a film that is optically responsive to pH and glucose, made of regenerated silk fibroin, laponite, organic dye and glucose oxidase enzyme. The goal also included that the film should be produced with simple methods, such as adsorption and mixing in water. 2 dyes well suited for adsorbing onto laponite while still retaining pH responsive, Neutral red and Thionine acetate, were selected in a screening by UV-vis spectrophotometry and spectrofluorimetry. A factorial design experiment was conducted to optimize the ratios of silk, laponite and dye for greatest response in absorbance and fluorescence. New films of the chosen recipe, containing Neutral red, were produced and tested for photo-stability and operational stability over several cycles of pH altering. No enhanced photostability was observed, but repeatability was observed over the tested cycles. To demonstrate glucose sensing as an application of the films, new films of the optimized recipe with co-immobilized glucose oxidase were produced and immersed in glucose solutions ranging from 0-300uM. Signal in absorbance from the activity of the glucose oxidase was observed, demonstrating that the principle worked. Further studies are needed to optimize the system and apply it to other more suitable purposes. As a continuation of creating a cheap, easily produced biosensor, the present report suggest a design for single wavelength absorbance- and fluorimetric detection based on LED technology. (Less)
Popular Abstract
This project used low-cost commodity materials and a simplified fabrication methods for making transparent, optically responsive films for measuring pH or glucose levels in a solution. Everything is done in water with a very stable end product. This demonstrates the diverse possibilities of silk proteins for functional material applications.
The environment has a central role in our modern societies, this in turn drives industry towards greener and more energy efficient materials and processes. As enzymes are both green and efficient, new uses for them as biocatalysts or biosensors are widely sought after. Efficient immobilization of enzymes onto manageable sized materials allows for reuse of enzymes, which is attractive if the... (More)
This project used low-cost commodity materials and a simplified fabrication methods for making transparent, optically responsive films for measuring pH or glucose levels in a solution. Everything is done in water with a very stable end product. This demonstrates the diverse possibilities of silk proteins for functional material applications.
The environment has a central role in our modern societies, this in turn drives industry towards greener and more energy efficient materials and processes. As enzymes are both green and efficient, new uses for them as biocatalysts or biosensors are widely sought after. Efficient immobilization of enzymes onto manageable sized materials allows for reuse of enzymes, which is attractive if the immobilization is cost-effective and stable.
Most of the project was aimed at developing a pH-responsive transparent film made of silk. Film consists of clay nanoparticles (Laponite), some pH-indicator dyes adsorbed on the laponite and silk proteins. The Laponite clay gives increased strength to the silk. It also provides a support to attach the pH indicator dye without further leakage. A suitable dye was selected and the recipe for making the films was optimized. This resulted in a see-through colored film. The film could change color and fluorescence as a result of different pHs. By including the enzyme glucose oxidase into the recipe, this pH sensor could be turned into a glucose sensor as well. Glucose oxidase catalyzes conversion of glucose into an acid, which decreases the pH and so changes the color of the film.
Because of the textile industry, low quality silk fibre is a relatively cheap bulk commodity. Laponite is also a bulk commodity, because it is used in many cosmetics products and food. Neither is considered toxic and both show remarkable properties. Particularly the mechanics of silk and the adsorption possibilities of Laponite are widely useful.
This project combined these two materials, to devise responsive, reusable and environment-friendly film. The manufacturing was very easy – just mixing the right proportions in the right order, all in water. This demonstrates the great possibilities of using silk-laponite and will hopefully inspire new uses in the industries. (Less)
Please use this url to cite or link to this publication:
author
Toytziaridis, Andreas LU
supervisor
organization
alternative title
Glucose- and pH sensitive silk films
course
KBK820 20161
year
type
H2 - Master's Degree (Two Years)
subject
keywords
colorimetric sensor, pH, glucose oxidase, Thionine acetate, Neutral Red, Silk, Laponite, biosensor, sensor, applied biochemistry, tillämpad biokemi
language
English
additional info
The alternative title is the title for the popular abstract.
id
8883219
date added to LUP
2016-06-27 10:02:32
date last changed
2016-06-27 10:02:32
@misc{8883219,
  abstract     = {Five consecutive experiments were conducted with the goal to produce a chromogenic silk film, namely a film that is optically responsive to pH and glucose, made of regenerated silk fibroin, laponite, organic dye and glucose oxidase enzyme. The goal also included that the film should be produced with simple methods, such as adsorption and mixing in water. 2 dyes well suited for adsorbing onto laponite while still retaining pH responsive, Neutral red and Thionine acetate, were selected in a screening by UV-vis spectrophotometry and spectrofluorimetry. A factorial design experiment was conducted to optimize the ratios of silk, laponite and dye for greatest response in absorbance and fluorescence. New films of the chosen recipe, containing Neutral red, were produced and tested for photo-stability and operational stability over several cycles of pH altering. No enhanced photostability was observed, but repeatability was observed over the tested cycles. To demonstrate glucose sensing as an application of the films, new films of the optimized recipe with co-immobilized glucose oxidase were produced and immersed in glucose solutions ranging from 0-300uM. Signal in absorbance from the activity of the glucose oxidase was observed, demonstrating that the principle worked. Further studies are needed to optimize the system and apply it to other more suitable purposes. As a continuation of creating a cheap, easily produced biosensor, the present report suggest a design for single wavelength absorbance- and fluorimetric detection based on LED technology.},
  author       = {Toytziaridis, Andreas},
  keyword      = {colorimetric sensor,pH,glucose oxidase,Thionine acetate,Neutral Red,Silk,Laponite,biosensor,sensor,applied biochemistry,tillämpad biokemi},
  language     = {eng},
  note         = {Student Paper},
  title        = {Chromogenic silk films - application to pH and glucose detection},
  year         = {2016},
}