Sol–Gel Encapsulation of Thymol Blue in Presence of Some Surfactants

Kodeh, Fawzi S.; El‐Nahhal, Issa M.; El-Salam, Fatma H. Abd

doi:10.1007/s42250-018-00039-6

Cited by 5 publications

(4 citation statements)

References 21 publications

(39 reference statements)

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“…The increase in ε max (λ 2 ) and the acidic shift of the conditional pK A from 4.19 to 2.76 indicated a clear interaction of the anionic species of the indicator with the cationic head group of CTApTs. As described elsewhere [31,32], the formation of the I − ||T + ion pair in solution occurred. The isosbestic point, occurring in the presence of an excess of T, showed that in these conditions only two species were at equilibrium (HI and T + ||I − ) as [I − ] was negligible.…”

Section: Absorption Spectra Of the Solutions Of Bpbmentioning

confidence: 77%

Modeling the Dichromatic Behavior of Bromophenol Blue to Enhance the Analytical Performance of pH Colorimetric Sensor Arrays

et al. 2022

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The dichromatism of Bromophenol blue (BPB) was investigated by varying its concentration in the absence and presence of surfactant. A model of the indicator behavior was carried out, justifying the experimental shapes of the sigmoidal profiles of the hue (H) coordinate. The model applied to the solution was compared with the performance of colorimetric sensor arrays (CSAs) with increasing BPB concentrations. The H shape and the prediction errors of the CSAs were very similar to those predicted. The experimental results enable the changing of the slope of the calibration profiles, at will, by varying only the BPB concentration.

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Section: Absorption Spectra Of the Solutions Of Bpbmentioning

confidence: 77%

Modeling the Dichromatic Behavior of Bromophenol Blue to Enhance the Analytical Performance of pH Colorimetric Sensor Arrays

et al. 2022

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“…From the simple litmus paper [ 32 , 33 ], in the last 15 years, a great evolution of more and more complex polymer matrices has widened the audience and the attention of the scientific community concerning CSAs [ 26 , 34 , 35 ]. Nevertheless, they suffer from various issues: errors due to the acquisition of the signal (the solution is interposed between the CCD camera and the CSA), leaching effects or irreversibility [ 36 ], slow time response [ 37 ], and low accuracy [ 38 ]. The first issue is quite difficult to solve [ 39 , 40 ].…”

Section: Introductionmentioning

confidence: 99%

Positively Charged Organosilanes Covalently Linked to the Silica Network as Modulating Tools for the Salinity Correction of pH Values Obtained with Colorimetric Sensor Arrays (CSAs)

Pastore,

Badocco,

Cappellin

et al. 2024

Sensors

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Seven increasing levels of water salinity from 0.029 to 0.600 M (as NaCl) were used to investigate the dependence of pH measurement, performed using colorimetric sensor arrays (CSAs), on ionic strength. The CSAs were arrays of sensing spots prepared in the form of sol–gel-embedding Bromothymol Blue (BB) and Bromocresol Green (BCG) in a porous nitrocellulose support. The support was impregnated over the entire thickness (≈100 µm), allowing for the signal (Hue) acquisition on the opposite side to the contact with the sample solution. Three CSAs were prepared, M1, M2, and M3. M1 contained a free cationic surfactant, hexadecyltrimethylammonium p-toluenesulfonate (CTApTs), for modulating the pKa of the indicators. In M2, the surfactant dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (DTSACl) was covalently bonded to the sol–gel. M3 was prepared like M2 but using a larger amount of ethanol as the solvent for the synthesis. The modulation of the CTApTs or the DTSACl concentration enabled the tuning of the pKa. In general, the pKa modulation ability decreased with the increase in salinity. The presence of a surfactant covalently linked to the backbone partially reduced the competitiveness of the anionic species, improving the results. Nevertheless, the salt effect was still present, and a correction algorithm was required. Between pH 5.00 and 12.00, this correction could be made automatically by using spots taken as references to produce sensors independent of salinity. As the salt effect is virtually absent above 0.160 M, M2 and M3 can be used for future applications in seawater.

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“…Stimuli-responsive polymers have attracted growing interest over the last few decades for a diverse range of applications, e.g., drug delivery, gene delivery, sensors, and tissue engineering [1][2][3]. Inspired by natural living cells, stimuli-responsiveness is a crucial function for maintaining human body balance and self-healing.…”

Section: Introductionmentioning

confidence: 99%