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Questions and Answers
What model drugs were used to examine the release from the hydrogels?
What model drugs were used to examine the release from the hydrogels?
Which method was used to determine the interior morphology of the hydrogels?
Which method was used to determine the interior morphology of the hydrogels?
How does the pH value of the buffer solution affect the hybrid hydrogels?
How does the pH value of the buffer solution affect the hybrid hydrogels?
What type of sensitivities do the hybrid hydrogels exhibit?
What type of sensitivities do the hybrid hydrogels exhibit?
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What polymer is mentioned as part of the hybrid hydrogel composition?
What polymer is mentioned as part of the hybrid hydrogel composition?
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In the study of swelling behavior, what characteristic of the hybrid hydrogels was analyzed?
In the study of swelling behavior, what characteristic of the hybrid hydrogels was analyzed?
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What technique was primarily used for the synthesis of the hydrogels?
What technique was primarily used for the synthesis of the hydrogels?
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What analysis technique is mentioned for characterizing the hydrogels?
What analysis technique is mentioned for characterizing the hydrogels?
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What is a key property of chitosan that makes it suitable for biomedical applications?
What is a key property of chitosan that makes it suitable for biomedical applications?
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Which environmental stimuli can affect the properties of temperature-sensitive hydrogels?
Which environmental stimuli can affect the properties of temperature-sensitive hydrogels?
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What is the significance of the lower critical solution temperature (LCST) in PNIPAAm?
What is the significance of the lower critical solution temperature (LCST) in PNIPAAm?
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How does the swelling behavior of hydrogels change with temperature?
How does the swelling behavior of hydrogels change with temperature?
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What effect does composition ratio have on the swelling rate of samples?
What effect does composition ratio have on the swelling rate of samples?
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Which of the following applications are environment-sensitive hydrogels NOT commonly used for?
Which of the following applications are environment-sensitive hydrogels NOT commonly used for?
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What role do hydrophilic segments play in the behavior of PNIPAAm above the LCST?
What role do hydrophilic segments play in the behavior of PNIPAAm above the LCST?
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What is the impact of pH on the swelling behavior of pH-sensitive hydrogels?
What is the impact of pH on the swelling behavior of pH-sensitive hydrogels?
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What factor predominantly influences the swelling ratio (SR) of PNIPAAm hydrogel at 37 ◦ C?
What factor predominantly influences the swelling ratio (SR) of PNIPAAm hydrogel at 37 ◦ C?
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How does the introduction of chitosan affect the swelling ratio (SR) of hybrid hydrogels at 37 ◦ C?
How does the introduction of chitosan affect the swelling ratio (SR) of hybrid hydrogels at 37 ◦ C?
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What happens to the swelling ratio (SR) of hybrid hydrogels as the pH of the buffer solution increases?
What happens to the swelling ratio (SR) of hybrid hydrogels as the pH of the buffer solution increases?
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What characteristic of chitosan contributes to the pH-sensitivity of polyelectrolyte hydrogels?
What characteristic of chitosan contributes to the pH-sensitivity of polyelectrolyte hydrogels?
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In the context of hydrogel formulations, what does the term 'equilibrium swelling ratio' refer to?
In the context of hydrogel formulations, what does the term 'equilibrium swelling ratio' refer to?
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Which sample demonstrated a distinct change in swelling ratio with varying pH levels?
Which sample demonstrated a distinct change in swelling ratio with varying pH levels?
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What effect does pH have on the swelling behavior of hydrogels in acidic solutions compared to neutral solutions?
What effect does pH have on the swelling behavior of hydrogels in acidic solutions compared to neutral solutions?
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What role do the covalently crosslinked structures between chitosan and PNIPAAm chains play?
What role do the covalently crosslinked structures between chitosan and PNIPAAm chains play?
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Study Notes
Photopolymerization of Methacrylated Chitosan/PNIPAAm Hybrid Hydrogels
- A series of hybrid hydrogels were designed using glycidyl methacrylated chitosan (CS-GMA) and N-isopropylacrylamide (NIPAAm) via photopolymerization.
- Hydrogels were characterized using FT-IR, DSC, and optical transmittance.
- Scanning electron microscopy (SEM) examined the hydrogel morphology.
- Swelling experiments showed pH and temperature sensitivity in the hybrid hydrogel.
- Acid orange 8 (AO8) and 5-fluorouracil (5-Fu) were used as model drugs to test release profiles.
- Hydrogel composition and buffer pH significantly affected drug release.
Synthesis of Glycidyl Methacrylated Chitosan (CS-GMA)
- Chitosan (Mw = 200 kDa, degree of deacetylation = 88%) reacted with glycidyl methacrylate (GMA) via epoxy ring opening reaction in acetic acid at 60°C.
- The degree of substitution (DS) was approximately 10.4%.
- This was determined using 1H NMR.
Preparation of CS-GMA/PNIPAAm Hybrid Hydrogels
- CS-GMA and NIPAAm were photopolymerized using a UV-light.
- Various compositions were prepared, each with varying amounts of CS-GMA and NIPAAm.
- The hydrogels were immersed in water to leach residues before further measurements.
FT-IR Analysis
- FT-IR spectra of CS-GMA, PNIPAAm, and a hybrid hydrogel (Sample C2) were analyzed.
- Key peaks indicated the presence of chitosan, indicating GMA incorporation.
- Also showed presence of amide I, amide II, and isopropyl groups (from PNIPAAm).
- The peaks due to isopropyl group displayed lower intensity for the hybrid hydrogel, suggesting crosslinking.
Phase Transition Studies
- DSC thermograms showed a slight increase in the lower critical solution temperature (LCST).
- The LCST was higher in the hybrid hydrogel (34.7°C) than in pure PNIPAAm hydrogel (33.4°C).
- Optical transmittance measurements supported pH/temperature sensitivity observations.
- Lower CS-GMA concentration hydrogels showed more obvious phase transition.
Swelling Kinetics and Equilibrium Swelling Ratio (SReq)
- Swelling kinetics were studied gravimetrically.
- Swelling ratios increased with time but reached equilibrium.
- Hybrid hydrogel swelling rates were faster than PNIPAAm hydrogels.
pH and Temperature Dependence of Swelling
- Swelling ratio was found to depend on both pH and temperature.
- At lower pH (acidic), swelling was greater than at higher pH (basic).
- At higher temperature, swelling was lower due to hydrophobic interactions.
- The hybrid hydrogel's swelling behaviour showed pH-dependence due to ionization of amine groups in chitosan.
Drug Release Analysis
- AO8 and 5-Fu were used as model drugs.
- Drug release was affected by pH.
- Release rates varied based on CS-GMA composition.
- Initial burst release followed slower release for some samples.
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Description
This quiz explores the synthesis and characterization of methacrylated chitosan/PNIPAAm hybrid hydrogels. Participants will learn about photopolymerization, hydrogel morphology, and the impact of pH and temperature on drug release profiles. Dive into the fascinating world of polymer science and drug delivery systems.
