| Summary: | 碩士 === 國立中央大學 === 化學工程與材料工程研究所 === 100 === The sense of taste is a specialized chemosensory system dedicated to the evaluation of food and drink. The taste has important roles in the development of oral pharmaceutical formulation, and the control of food quality. Thus, we propose to mimic the working principle of a human tongue through the use of fascinating luminescent materials of metal-organic frameworks (i.e. [In(OH)bdc]n and Tb(btc) (namly, MOF-76)).
In this study, solvothermal method was used to synthesis metal organic frameworks and characterized by POM, FT-IR, PL, TGA and PXRD. We have used the photoluminescence (PL) responses of polyacrylic acid-chelated [In(OH)bdc]n and lanthanide Tb(btc) to demonstrate the applicability of MOF-based biomimetic tongue through: (1) identification of five tastes of sweet, bitter, sour, salty and umami by 2-D PCA to distinguish the corresponding tastants of sucrose, caffeine, citric acid, sodium chloride and monosodium glutamate. The plot of PL emission wavelengths of λ = 344, 436, 347, 394, and 335 nm for sucrose-, caffeine-, citric acid-, sodium chloride-, and monosodium glutamate-adsorbed polyacrylic acid-chelated [In(OH)bdc]n as x-coordinates and the slopes of equations between PL emission intensities and concentrations of tastants: 96.1, 126.9, 70.4, 40.5, and 140.8 for sucrose-, caffeine-, citric acid-, sodium chloride-, and monosodium glutamate-adsorbed MOF-76 as y-coordinates. (2) quantification of the strength of five tastes determined by the relationships between the PL intensity and the τ scale of taste. The detection time is 12 h and the detection range of concentrations is from 10-1 M to 10-5 M in this study.
There are several important features of our MOF-based “biomimetic tongue”: (1) poly(acrylic acid) (PAA) on [In(OH)(bdc)]n is implemented to mimic the structural flexibility of taste receptor cells (TRCs), (2) the analogue of the Weber-Fechner Law of Human Sensing that sensation is proportional to the logarithm of the stimulus intensity is observed between the PL emission response of MOF-76 and the concentration of the tastant, (3) the strength of taste can be quantified by the ? scale and the PL emission intensity of MOF-76, both of which are dependent on the logarithmic concentration of the tastant, (4) the tastant is identified and distinguished based on a pattern recognition method (i.e. principal component analysis).
Finally, this study have developed a method to fabricate the [In(OH)bdc]n/PAA film by brushing. The advantages of this method were: (1) [In(OH)bdc]n could be easily brushed on surfaces of substrate or cover glass to form a transparent thin film, (2) [In(OH)bdc]n could be also spread evenly on the surfaces, and (3) it is convenient to make [In(OH)bdc]n/PAA film through brushing the resulting solution on substrates.
|
|---|
