Autor(es): Bertão, Ana Raquel Carvalho
Data: 2017
Identificador Persistente: https://hdl.handle.net/1822/77479
Origem: RepositóriUM - Universidade do Minho
Assunto(s): Urinalysis; Zeolites; Dyes molecules; Encapsulation; Paper-based analytical devices; Colorimetric studies; Análise de urina; Zeólitos; Corantes; Encapsulação; Dispositivos de análise de microfluídica em papel; Estudos colorimétricos
Currently there is a need for diagnosis processes, which uses urine samples and offer quick, easy, and accurate results, since most of the traditional systems require time, material, facilities, and specialized personnel, which can affect the efficiency of the therapy chosen for the patient. In this context, this work reports two different strategies to improve the stability and latency of the results provided by a device specifically developed for the analysis of urine samples on diapers and early medical condition assessment. The main goal was to obtain stable, rapid, and easily interpretable results, by employing colorimetric detection, without the need of electricity to analyze several urine biomarkers. The device design already comprises components to provide the conditions for the results stability, such as a self-locking system and a cover layer. These same conditions were tested, and the outcomes suggest that the device has great potential to keep valid results for long periods. The encapsulation of the dye molecules, normally used in the bioassays, into hosts like zeolites nanostructures, which were used to enhance color stability, was also studied in order to have a chemical approach to this issue. These obtained dye nanomaterials were characterized by employing several techniques (Room Temperature Fourier Transform Infrared (FTIR), N2 adsorption isotherms, scanning electron microscopy (SEM/EDX), thermogravimetric analysis (TGA) and powder X-ray diffraction (XRD)) and, the results show that the encapsulation of the dyes was successfully achieved, preserving both the guest and host structures. Regarding the colorimetric results, a long-time stability of the dye colors was achieved due to their encapsulation into the zeolite nanostructures. The choice of the type of paper for the μPAD and the zeolite nanostructures properties influences the colorimetric response. The results obtained in this work were promising for the studied assays, and the strategy could also be extended to other biomarkers.
