Luminescence can be utilized in various commercially important applications such as anti-counterfeit (AC) markings and bioaffinity assays. The increasing demands for product authentication by consumers, and point-of-care (POC) health monitoring systems, can be met using luminescence based solutions developed to be compatible with simple instrumentation such as smartphones. Use of environmentally friendly materials like cellulose would further benefit such applications. In this thesis, the luminescence properties of fibrillary cellulose films and cardboard materials are studied to find a cellulose based material usable as a substrate for luminescent AC markers. Multiple combinations of organic luminophores, lanthanide chelates and inorganic phosphors have been used to create datasets i.e. luminescence topography maps (LTM) for verification of the authenticity of the product package. The whole authentication process, from the photoexcitation of the marker to the recognition of the product, is demonstrated with a smartphone application. Wide variety of marker luminophores can be used in the future, as camera technologies and computing power of the smartphones are constantly evolving. The results also show that cellulose as substrate displays weak long-lived photoluminescence emission. This emission originating from multiple luminescence centers, can be utilized in LTM as an internal standard in the method. Cellulose based composite materials are also investigated as low-cost alternatives for expensive oxide-coated silicon electrodes for electrochemiluminoimmunoassays. Composite electrodes made of insulating cellulose derivatives or polystyrene with different conductive carbon materials are studied, and these materials are used to make screen-printed electrode chips. The analytical applicability of the electrodes have been tested in immunoassay of C-reactive protein with Tb(III)chelate and fluorescein isothiocyanate (FITC) labels. The results indicate that conductive carbon-cellulose composite materials are well suited for the fabrication of screen-printed electrodes. Low background emission, wide linear range and low detection limits are obtained with these electrodes. FITC could provide lower detection limits of the analyte than the presently used Tb(III) chelate labels, which is very promising for low-cost POCT applications.
|Translated title of the contribution||Luminoivat merkki- ja leima-aineet autentikoinnissa ja bioaffiniteettimäärityksissä|
|Publication status||Published - 2020|
|MoE publication type||G5 Doctoral dissertation (article)|
- composite electrodes
- bioaffinity assays