Optical pH sensor based on polyelectrolyte complex (PEC) pectin-chitosan/methanol anthocyanin extract of Catharanthus roseus for a new optical urea biosensor development

Construction of optical pH sensor as a new platform optical urea biosensor based on polyelectrolyte complex (PEC) pectin-chitosan membrane and total phenolic (anthocyanin) of Tapak Dara flower (Catharanthus roseus) has been successfully carried out. The anthocyanin was extracted by a maceration method for 72 hours using methanol, and a total extract yield was 21.56% or 1.803 mg/L. Flavonoid and phenol tests showed positive results indicated by the formation of red and black colours. The anthocyanins showed maximum absorption at 578 nm for phosphate buffer and 575 nm for tris HCl buffer solution. The sensor fabrication was performed using a mixture of pectin and chitosan solutions with a ratio of 3:7. The anthocyanin was mixed into the solution with various concentrations. The sensor has an optimum sensitivity at the anthocyanin concentration of 0.05 mg/L (phosphate buffer) in the pH range of 7.0-9.5 and 0.025 mg/L (Tris HCl buffer) with a narrower pH range of 6.0-7.5. This sensor produced higher sensitivity, a wider linear range, and good linearity when it was exposed in 0.03M PBS. Reproducibility test with a relative standard deviation percentage (% RSD) was 9.20. The sensor showed a stable response after 5 minutes exposed to PBS solution, and it can be used to measure pH within the 20th day. The optimized optical pH sensor has been successfully developed as a urea optical biosensor by immobilizing urease on its surface. The biosensor showed a linear response in a series of 10-1-10-10 M urea concentrations and has good linearity.

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Optical pH Sensor Based on Immobilization Anthocyanin from Dioscorea alata L. onto Polyelectrolyte Complex Pectin–Chitosan Membrane for a Determination Method of Salivary pH

Polymers ◽

10.3390/polym13081276 ◽

2021 ◽

Vol 13 (8) ◽

pp. 1276

Author(s):

Eka Safitri ◽

Hani Humaira ◽

Murniana Murniana ◽

Nazaruddin Nazaruddin ◽

Muhammad Iqhrammullah ◽

...

Keyword(s):

Polyelectrolyte Complex ◽

Ph Sensor ◽

Dioscorea Alata ◽

Anthocyanin Content ◽

Buffer Solution ◽

Citrate Buffer ◽

Relative Standard ◽

Significant Difference ◽

Salivary Ph ◽

Optical Ph Sensor

A simple optical pH sensor based on immobilization, Dioscorea alata L. anthocyanin methanol extract, onto a pectin–chitosan polyelectrolyte complex (pectin–chitosan PEC), has been successfully fabricated. The optical pH sensor was manufactured as a membrane made of pectin–chitosan PEC and the extracted anthocyanin. This sensor has the highest sensitivity of anthocyanin content at 0.025 mg/L in phosphate buffer and 0.0375 mg/L in citrate buffer. It also has good reproducibility with a relative standard deviation (%RSD) of 7.7%, and gives a stable response at time values greater than 5 min from exposure in a buffer solution, and the sensor can be utilized within five days from its synthesis. This optical pH sensor has been employed to determine saliva pH of people of different ages and showed no significant difference when compared to a potentiometric method.

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A simple optical pH sensor based on pectin and Ruellia tuberosa L-derived anthocyanin for fish freshness monitoring

F1000Research ◽

10.12688/f1000research.52836.1 ◽

2021 ◽

Vol 10 ◽

pp. 422

Author(s):

Nazaruddin Nazaruddin ◽

Nurul Afifah ◽

Muhammad Bahi ◽

Susilawati Susilawati ◽

Nor Diyana Md. Sani ◽

...

Keyword(s):

Standard Deviation ◽

Room Temperature ◽

Ph Value ◽

Ph Sensor ◽

Phosphate Buffer Solution ◽

Good Sensitivity ◽

Buffer Solution ◽

C Storage ◽

Relative Standard ◽

Optical Ph Sensor

A simple optical pH sensor using the active compound anthocyanin (ACN), derived Ruellia tuberosa L. flower immobilized in a pectin membrane matrix, was been fabricated and employed to monitor the freshness of tilapia fish at room temperature and 4oC storage. The optimum pectin weight and ACN concentrations were 0.1% and 0.025 mg/L. The sensor showed good sensitivity at 0.03 M phosphate buffer solution. The sensor’s reproducibility was evaluated using 10 replicate sensors where a standard deviation of 0.045 or relative standard deviation of 9.15 was achieved. The sensor displayed an excellent response after 10 minutes of exposure, possessing a response stability for 10 consecutive days. The decrease in pH value of the Tilapia fish from 7.3 to 5 was observed in a 48 hour test, which can be used as the parameter when monitoring fish freshness.

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A simple optical pH sensor based on pectin and Ruellia tuberosa L-derived anthocyanin for fish freshness monitoring

F1000Research ◽

10.12688/f1000research.52836.2 ◽

2021 ◽

Vol 10 ◽

pp. 422

Author(s):

Nazaruddin Nazaruddin ◽

Nurul Afifah ◽

Muhammad Bahi ◽

Susilawati Susilawati ◽

Nor Diyana Md. Sani ◽

...

Keyword(s):

Standard Deviation ◽

Ph Value ◽

Ph Sensor ◽

Phosphate Buffer Solution ◽

Buffer Solution ◽

Rigor Mortis ◽

C Storage ◽

Relative Standard ◽

Vis Spectroscopy ◽

Optical Ph Sensor

A simple optical pH sensor using the active compound anthocyanin (ACN), derived Ruellia tuberosa L. flower immobilized in a pectin membrane matrix, was been fabricated and employed to monitor the freshness of tilapia fish at room temperature and 4oC storage. The quantitative pH values were measured based on the UV-Vis spectroscopy absorbance. The optimum pectin weight and ACN concentrations were 0.1% and 0.025 mg/L. The sensor showed good sensitivity at 0.03 M phosphate buffer solution. The sensor’s reproducibility was evaluated using 10 replicate sensors where a standard deviation of 0.045 or relative standard deviation of 9.15 was achieved. The sensor displayed an excellent response after 10 minutes of exposure, possessing a response stability for 10 consecutive days. The decrease in pH value of the Tilapia fish from 7.3 to 5 was observed in a 48 hour test, which can be used as the parameter when monitoring fish freshness. Overall, this reported optical pH sensor has a novelty as it could be used to monitor the rigor mortis phase of fish meat, which is useful in food industry.

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Near-Infrared pH Sensor Based on a SPEEK–Polyaniline Polyelectrolyte Complex Membrane

Proceedings ◽

10.3390/iocn_2018-1-05493 ◽

2018 ◽

Vol 3 (1) ◽

pp. 11 ◽

Cited By ~ 1

Author(s):

Nedal Y. Abu-Thabit

Keyword(s):

Polyelectrolyte Complex ◽

Near Infrared ◽

Response Times ◽

Oxidative Polymerization ◽

Ph Sensor ◽

Ph Sensing ◽

Ph Values ◽

Sensing Applications ◽

Ph Range ◽

Speek Membrane

A polyelectrolyte complex (PEC) membrane based on sulfonated poly (ether ether ketone) and polyaniline (SPEEK-PANI) was developed for pH sensing applications. Aniline was polymerized in the presence of the SPEEK membrane by using in situ chemical oxidative polymerization to yield an ionically crosslinked SPEEK-PANI membrane. The fabricated membrane exhibited sensitivity in the physiological pH range of 2–8. The PEC membrane pH sensor showed good absorption properties in the near-infrared region (NIR). The membrane showed fast response during a de-doping process (≈90 s), while longer response times are essential for doping processes from the alkaline/neutral pH region to the acidic pH region, which is attributed to the presence of highly acidic sulfonic acid groups with a high buffering capacity in the PEC membrane. The SPEEK-PANI membrane exhibited slightly higher water uptake compared to the neat SPEEK membrane. The membrane exhibited good stability, as it was stored in 1M HCl solution for more than 2 years without physical or visual deterioration. A preconditioning step in 1M HCl ensured that the results were reproducible and allows the pH sensor to be used repeatedly. The PEC sensor membranes are suitable for applications that start at low pH values and move upwards to higher pH values in the 2–8 pH range.

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Preparation and Characterization of a Pectin Membrane-Based Optical pH Sensor for Fish Freshness Monitoring

Biosensors ◽

10.3390/bios9020060 ◽

2019 ◽

Vol 9 (2) ◽

pp. 60 ◽

Cited By ~ 15

Author(s):

Uswatun Hasanah ◽

Mita Setyowati ◽

Rustam Efendi ◽

Muslem Muslem ◽

Nor Diyana Md Sani ◽

...

Keyword(s):

Standard Deviation ◽

Response Time ◽

Relative Standard Deviation ◽

Ph Sensor ◽

Sensor Response ◽

Relative Standard ◽

Optical Ph Sensor

In a simple and instant procedure for detecting fish freshness, a hydrogel and hydrophilic pectin matrix membrane was used successfully as an optical pH sensor by immobilizing the chromoionophore ETH 5294 (CI), which is very selective and sensitive for the membrane. The Pe/CI optical pH sensor exhibited excellent linearity between pH 5 and pH 9, with a sensor response time of 5 min and reproducibility of 1.49% relative standard deviation (RSD). The sensor showed response stability for 15 days and a response reduction of 8.6%. The sensor’s capability was demonstrated by the detection of fish freshness for 17 days at 4 °C.

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Tris/Tris·HCl: A Standard Buffer for Use in the Physiologic pH Range

Clinical Chemistry ◽

10.1093/clinchem/18.3.206 ◽

1972 ◽

Vol 18 (3) ◽

pp. 206-208 ◽

Cited By ~ 65

Author(s):

Richard A Durst ◽

Bert R Staples

Keyword(s):

Phosphate Buffer ◽

Silver Chloride ◽

Chloride Cells ◽

Reference Solution ◽

Buffer Solution ◽

Hydrochloride Salt ◽

Ph Values ◽

Standard Buffer ◽

Ph Range ◽

Ph Standard

Abstract A buffer solution containing tris(hydroxymethyl)-aminomethane (0.01667 mol/kg) and its hydrochloride salt (0.0500 mol/kg) is proposed as a pH standard for the physiologically important pH range of 7.3 to 7.5. Standard pH values were assigned to this reference solution at temperatures from 0° to 50°C by means of measurements with hydrogen/silver chloride cells without transference. At 37°C, the assigned pH of this buffer solution is 7.382, with a temperature coefficient of -0.026 pH unit per degree Celsius. This new standard is more compatible with biologic fluids than is the previously certified phosphate buffer.

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Fabrication of an Immobilized Polyelectrolite Complex (PEC) Membrane from Pectin-Chitosan and Chromoionophore ETH 5294 for pH-Based Fish Freshness Monitoring

Coatings ◽

10.3390/coatings12010088 ◽

2022 ◽

Vol 12 (1) ◽

pp. 88

Author(s):

Eka Safitri ◽

Zatul Omaira ◽

Nazaruddin Nazaruddin ◽

Irfan Mustafa ◽

Sitti Saleha ◽

...

Keyword(s):

Accurate Determination ◽

Active Material ◽

Ph Sensor ◽

Wavelength Region ◽

Trial And Error ◽

Optimum Conditions ◽

Relative Standard ◽

Optimum Wavelength ◽

Optical Ph Sensor

Considering the significance of its demand around the world, the accurate determination of fish freshness with a simple and rapid procedure has become an interesting issue for the fishing industry. Hence, we aimed to fabricate a new optical pH sensor based on a polyelectrolyte (PEC) membrane of pectin–chitosan and the active material chromoionophore ETH 5294. A trial-and-error investigation of the polymer compositions revealed that the optimum ratio of pectin to chitosan was 3:7. With an optimum wavelength region (λ) at 610 nm, the constructed sensor was capable of stable responses after 5 min exposure to phosphate-buffered solution. Furthermore, the obtained sensor achieved optimum sensitivity when the PBS concentration was 0.1 M, while the relative standard deviation values ranged from 2.07 to 2.34%, suggesting good reproducibility. Further investigation revealed that the sensor experienced decreased absorbance of 16.67–18.68% after 25 days of storage. Employing the optimum conditions stated previously, the sensor was tested to monitor fish freshness in samples that were stored at 4 °C and ambient temperature. The results suggested that the newly fabricated optical sensor could measure pH changes on fish skin after 25 h storage at room temperature (pH 6.37, 8.91 and 11.02, respectively) and 4 °C (pH 6.8, 7.31 and 7.92, respectively).

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Polypyrrole–Methyl Orange Raman pH Sensor

Polymers ◽

10.3390/polym11040715 ◽

2019 ◽

Vol 11 (4) ◽

pp. 715 ◽

Cited By ~ 4

Author(s):

Tomasz Czaja ◽

Kamil Wójcik ◽

Maria Grzeszczuk ◽

Roman Szostak

Keyword(s):

Methyl Orange ◽

Raman Spectra ◽

Ph Value ◽

Ph Sensor ◽

First Case ◽

Relative Standard ◽

Wide Ph Range ◽

Analogous Model ◽

Ph Range

An easy-to-prepare pH sensor based on electrochemically obtained polypyrrole doped with methyl orange ions is described. It enables the determination of a pH value in the 3–13 range for volumes below 1 µL. In a wide pH range, resonance and pre-resonance methyl orange Raman spectra, excited with the 514.5 nm line of an Ar+ laser, changed noticeably in function of H+ concentration. Two types of measurements were performed. In the first case, Raman spectra of the analyzed solutions were collected for samples placed on the sensor surface using a confocal microscope equipped with a 10x objective. Next, measurements were conducted for the same samples without the sensor. On the basis of these spectra, partial least-squares models were elaborated and validated. Relative standard errors of prediction for calibration, validation, and test samples were found to be in the 3.7%–3.9% range. An analogous model build using spectra registered without the sensor was characterized by slightly worse parameters.

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Grand-Reaction Method for Simulations of Ionization Equilibria and Ion Partitioning in a Broad Range of pH and Ionic Strength

10.26434/chemrxiv.9741746.v1 ◽

2019 ◽

Author(s):

Jonas Landsgesell ◽

Oleg Rud ◽

Pascal Hebbeker ◽

Raju Lunkad ◽

Peter Košovan ◽

...

Keyword(s):

Mean Field ◽

Coarse Grained ◽

Reactive System ◽

Acid Base ◽

Buffer Solution ◽

Reaction Method ◽

Ionization Equilibria ◽

Coarse Grained Simulations ◽

Ph Range ◽

Weak Polyelectrolytes

We introduce the grand-reaction method for coarse-grained simulations of acid-base equilibria in a system coupled to a reservoir at a given pH and concentration of added salt. It can be viewed as an extension of the constant-pH method and the reaction ensemble, combining explicit simulations of reactions within the system, and grand-canonical exchange of particles with the reservoir. Unlike the previously introduced methods, the grand-reaction method is applicable to acid-base equilibria in the whole pH range because it avoids known artifacts. However, the method is more general, and can be used for simulations of any reactive system coupled to a reservoir of a known composition. To demonstrate the advantages of the grand-reaction method, we simulated a model system: A solution of weak polyelectrolytes in equilibrium with a buffer solution. By carefully accounting for the exchange of all constituents, the method ensures that all chemical potentials are equal in the system and in the multi-component reservoir. Thus, the grand-reaction method is able to predict non-monotonic swelling of weak polyelectrolytes as a function of pH, that has been known from mean-field predictions and from experiments but has never been observed in coarse-grained simulations. Finally, we outline possible extensions and further generalizations of the method, and provide a set of guidelines to enable safe usage of the method by a broad community of users.<br><br>

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Comprehensive analysis of the isozyme composition of laccase derived from Japanese lacquer tree, Toxicodendron vernicifluum

Journal of Wood Science ◽

10.1186/s10086-021-01943-1 ◽

2021 ◽

Vol 67 (1) ◽

Author(s):

Mariko Takano ◽

Masaya Nakamura ◽

Masanobu Tabata

Keyword(s):

Isoelectric Focusing ◽

Laccase Activity ◽

Maximum Activity ◽

Acetone Powder ◽

Blue Color ◽

Buffer Solution ◽

Activity Staining ◽

Water Extracts ◽

Ph Range ◽

Toxicodendron Vernicifluum

AbstractWe performed an analysis using isoelectric focusing to comprehensively clarify the isozyme composition of laccase derived from Japanese lacquer tree, Toxicodendron vernicifluum. When water extracts of acetone powder obtained from lacquer were subjected to isoelectric focusing, five bands within pI 7.35–9.30 and nine bands within pI 3.50–5.25 were detected using Coomassie staining. Similarly, laccase activity staining using guaiacol showed five bands within pI 7.35–9.30 and three bands within pI 3.50–4.25. However, laccase activity staining using gallic acid showed remarkable staining within pI 3.50–5.85, whereas staining was very weak within pI 7.35–9.30. When the water extracts of acetone powder were fractionated into the fractions containing bands within pI 7.35–9.30 and pI 3.50–5.85 by SP-Sepharose column chromatography, the former had a blue color and the latter a yellow color. The laccase activity was measured for each of the fractions in buffer solution in the pH range of 2.5–8.0. When syringaldazine, guaiacol, and 2,6-dimethoxyphenol were used as substrates, the yellow fraction showed considerably higher activity than the blue fraction for pH 5.5–7.5. When 3-methylcatechol and 4-methylcatechol were used as substrates, the yellow fraction showed higher activity for pH 4.5–6.5, and the blue fraction showed higher activity for pH 7.0–8.0. When 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) was used as the substrate, both fractions showed maximum activity at optimum pH of 3.0–4.0. Conventionally, in research on blue laccase derived from lacquer, the non-blue fraction corresponding to the yellow fraction lower than pI 6 has been removed during the purification process and thus has not been analyzed. Our results indicated that yellow laccase was present in the non-blue components of lacquer and that it may play a role in urushiol polymerization with previously reported blue laccase.

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