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Related Concept Videos

Buffers02:56

Buffers

172.8K
A solution containing appreciable amounts of a weak conjugate acid-base pair is called a buffer solution, or a buffer. Buffer solutions resist a change in pH when small amounts of a strong acid or a strong base are added. A solution of acetic acid and sodium acetate is an example of a buffer that consists of a weak acid and its salt: CH3COOH (aq) + CH3COONa (aq). An example of a buffer that consists of a weak base and its salt is a solution of ammonia and ammonium chloride: NH3 (aq) + NH4Cl...
172.8K
Buffers: Buffer Capacity01:09

Buffers: Buffer Capacity

2.3K
Buffer capacity is the quantitative measure of a buffer to resist the change in pH. As shown in the following equation, the buffer capacity, denoted by 'beta', is expressed as the number of moles of acid or base needed to change the pH of a one-liter buffer solution by 1 unit. Here, Ca and Cb indicate the number of moles of acid and base, respectively. Note that dpH represents the change in pH.
In the graph, pH is plotted as a function of the number of moles of base (Cb) added to a weak...
2.3K
Buffer Effectiveness02:19

Buffer Effectiveness

55.2K
Buffer solutions do not have an unlimited capacity to keep the pH relatively constant . Instead, the ability of a buffer solution to resist changes in pH relies on the presence of appreciable amounts of its conjugate weak acid-base pair. When enough strong acid or base is added to substantially lower the concentration of either member of the buffer pair, the buffering action within the solution is compromised.
The buffer capacity is the amount of acid or base that can be added to a given volume...
55.2K
Calculating pH Changes in a Buffer Solution02:45

Calculating pH Changes in a Buffer Solution

58.6K
A buffer can prevent a sudden drop or increase in the pH of a solution after the addition of a strong acid or base up to its buffering capacity; however, such addition of a strong acid or base does result in the slight pH change of the solution. The small pH change can be calculated by determining the resulting change in the concentration of buffer components, i.e., a weak acid and its conjugate base or vice versa. The concentrations obtained using these stoichiometric calculations can be used...
58.6K
Phosphate Buffer01:22

Phosphate Buffer

5.1K
The phosphate buffer system is a critical biological mechanism for maintaining pH stability in the body. This system operates primarily through two components: sodium dihydrogen phosphate (NaH2PO4), which acts as a weak acid, and sodium hydrogen phosphate (Na2HPO4), which serves as a weak base.
Sodium dihydrogen phosphate does not fully dissociate in neutral or acidic solutions. When a strong base, such as sodium hydroxide (NaOH), is introduced into the solution, sodium dihydrogen phosphate...
5.1K
Buffers: Overview01:30

Buffers: Overview

10.0K
Buffers play a crucial role in stabilizing the pH of a solution by mitigating the effects of small amounts of added acid or base. They consist of a weak acid and its conjugate base or a weak base and its conjugate acid. A solution of acetic acid and sodium acetate is an example of a buffer that consists of a weak acid and its salt: CH3COOH (aq) + CH3COONa (aq). An example of a buffer that consists of a weak base and its salt is a solution of ammonia and ammonium chloride: NH3 (aq) + NH4Cl (aq).
10.0K

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Localized pH Pulses in PBS Buffer Repeatedly Induced by Visible Light.

Adnan Elgattar1, Nawodi Abeyrathna1, Yi Liao1

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Researchers demonstrated a light-induced pH pulse in a buffered solution using a special polymer film. This photochemical pH modulation could offer new ways to study diseases and develop therapies.

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Area of Science:

  • Photochemistry
  • Biophysical Chemistry
  • Materials Science

Background:

  • Biological system pH is crucial for enzyme activity and implicated in diseases.
  • Controlling pH with light offers potential for studying pH effects and developing therapies.
  • Buffering in biological systems limits pH changes, posing a challenge for photochemical modulation.

Purpose of the Study:

  • To demonstrate a photoinduced pH pulse in an open system (PBS buffer).
  • To investigate the feasibility of generating a significant and sustained pH change using light.
  • To explore the potential of metastable-state photoacid (mPAH) polymers for photochemical pH control.

Main Methods:

  • Fabrication of a micrometer hydrophilic film using a metastable-state photoacid (mPAH) polymer.
  • Irradiation of the film with moderate visible light in a phosphate-buffered saline (PBS) solution.
  • Monitoring pH changes and proton exchange dynamics within the open system.

Main Results:

  • A reversible pH pulse was successfully generated in the PBS buffer upon visible-light irradiation.
  • The pH pulse exhibited a magnitude of 1.4-1.9 units, with maximum change around 18 seconds.
  • The mPAH polymer allowed for repeated generation of the pH pulse after recovery in the dark.

Conclusions:

  • Photochemical modulation of pH is achievable even in buffered biological-relevant solutions.
  • Metastable-state photoacid polymers can induce significant and repeatable pH pulses.
  • This approach holds promise for applications in biological research and therapeutic strategies.