Silver nanoparticles formation on fibres and potential for optical sensing
Loading...
URL
Journal Title
Journal ISSN
Volume Title
Kemian tekniikan korkeakoulu |
Master's thesis
Unless otherwise stated, all rights belong to the author. You may download, display and print this publication for Your own personal use. Commercial use is prohibited.
Authors
Date
2014-12-02
Department
Major/Subject
Renewable Materials Engineering
Mcode
KM3002
Degree programme
KEM - Kemian tekniikan koulutusohjelma
Language
en
Pages
56
Series
Abstract
Silver nanoparticles (AgNP) formation mediated by fibres in paper can be a promising process for optical sensing applications with high sensitivity and low cost. Thus, the aim of this thesis was to develop a paper-based sensor to quantify the concentration of analyte. The work focused on investigating the role of interactions between silver ions-cellulosic hydroxyl groups and analyte molecules in AgNP formation. A multilayer sensor module that included layers supporting silver ion precursor and ascorbic acid reducing agent was constructed. The effect of positional order of the sensor layers on AgNP formation was studied. UV-vis spectroscopy and SEM were used to characterize the AgNP plasmon effect and morphology, respectively. Initially, cationic (DDAB), anionic (SDS), and nonionic (Triton X) surfactants were used as model analytes carrying different electrostatic charges. Further investigation was performed with biomolecules including cholesterol, BSA, gamma-globulin. UV-vis absorption results of sensor modules with varied layer-order confirmed the pivotal role of cellulosic hydroxyls in AgNP nucleation and growth processes, which were characterized by the two typical plasmonic peaks located at short and long wavelengths (~420 and 500~600 nm, respectively). Compared with the nonionic and the surfactant-free conditions, the cationic and anionic surfactants yielded more uniform and reproducible results in terms of AgNP formation and respective plasmon signal. The investigation with cholesterol confirmed main findings with surfactants by revealing distinct blue shifts in the long wavelength plasmonic peaks. However, the results with BSA and gamma-globulin proteins were inconclusive due to the possible the interference of impurities or other causes not yet identified. The findings in this thesis not only are consistent with previous studies, but also highlight opportunities for sensor design based on AgNP formation process instead of traditional platforms based on pre-synthesized AgNP. Further work will be needed to understand the mechanism of blue shift caused by the analyte and to optimize its correlation with concentration in the presence of interfering substances.Description
Supervisor
Rojas, OrlandoThesis advisor
Arcot, LokanathanKeywords
paper sensor, silver nanoparticles, cellulose hydroxyl, surface plasmon resonance, UV-vis absorption