What are pH-sensitive hydrogels?
A pH-sensitive hydrogel is a gel structure that is sensitive to changes in pH. Most commonly, the hydrogel will swell or contract in response to a change in the local chemical environment.
What is a temperature-sensitive hydrogel?
Definition. Temperature-sensitive hydrogels, which are part of the family of stimulus-sensitive hydrogels, consist of water-filled polymer networks (i.e., gels) that display a temperature-dependent degree of swelling.
How does pH affect hydrogel absorption?
Effect of pH on swelling Slight change in swelling ratio of the biomineralized hydrogels has been noticed when placed in various pH of the aqueous solution. It can also be noticed that irrespective of sample thickness at neutral pH = 7, all samples show a higher value of swelling ratio.
What is pH for hydrogel?
pH responsive hydrogels are developed, which shows highest swelling capacity around physiological pH~ 7.4, compared to both acidic and basic medium. Synthesis of hydrogels using green azetidinium-amine reactions in water. Selective and controlled drug delivery at pH 7.4, compared to both acidic and basic medium.
How do pH responsive hydrogels work?
In CO2 sensors, a pH sensitive hydrogel disc comes in contact with bicarbonate solution. On exposure to CO2, the pH of solution changes resulting in swelling or deswelling of the hydrogel which causes a change in pressure which is a measure of the partial pressure of CO2.
How do pH sensitive polymers work?
pH sensitive or pH responsive polymers are materials which will respond to the changes in the pH of the surrounding medium by varying their dimensions. Materials may swell, collapse, or change depending on the pH of their environment.
What happens above the Lcst for the temperature sensitive hydrogels?
Above the LCST, they become increasingly hydrophobic and insoluble, leading to gel formation.
What are temperature responsive polymers used for?
Temperature-responsive polymers or thermoresponsive polymers are polymers that exhibit a drastic and discontinuous change of their physical properties with temperature. The term is commonly used when the property concerned is solubility in a given solvent, but it may also be used when other properties are affected.
Does humidity affect swelling ratio?
The overall trend shown in this study (Fig. 9) is that as the relative humidity increases, the swelling rate decreases. Relative humidity also has effect on the standard errors of the swelling model.
Why is chitosan pH sensitive?
Chitosan is a pH-responsive polymer, which remains in aqueous solution up to 6.2 [59]. It has pH-sensitive properties due to the protonation-deprotonation balance of amino groups, which allows the formulation of controlled release systems ( Figure 6) [60] .
What do temperature responsive polymers do?
What are injectable and body temperature sensitive hydrogels?
In response to this drawback, the injectable and body temperature (37 °C) sensitive hydrogels emerge. These hydrogels exist in a solution state at room temperature and can be injected into human body by simply using a syringe.
How do hydrogels work?
Hydrogels based on chitosan/hyaluronic acid/β-sodium glycerophosphate demonstrate injectability, body temperature sensitivity, pH sensitive drug release and adhesion to cancer cell. The drug (doxorubicin) loaded hydrogel precursor solutions are injectable and turn to hydrogels when the temperature is increased to body temperature.
How do hyaluronic acid hydrogels trigger drug release from cancer cells?
The acidic condition (pH 4.00) can trigger the release of drug and the cancer cell (Hela) can adhere to the surface of the hydrogels, which will be beneficial for tumor site-specific administration of drug. The mechanical strength, the gelation temperature, and the drug release behavior can be tuned by varying hyaluronic acid content.