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In this lab report, we investigate the swelling behavior of glyoxal, glutaraldehyde, and terephthaldehyde cross-linked chitosans (CLCS) and the in vitro release of acyclovir from acyclovir-loaded CLCS. We utilize various analytical techniques, including gravimetry, Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction, thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM) to evaluate the properties of the cross-linked chitosans and their potential as drug carriers.
Chitosan is a biodegradable polymer with a wide range of applications, including drug delivery systems.
Cross-linking chitosan can improve its stability and control drug release. In this study, we examine the swelling behavior of CLCS and assess the in vitro release of acyclovir, a model drug, from acyclovir-loaded CLCS.
We conducted a swelling test to observe the swelling behavior of CLCS. A gravimetric procedure was employed using the following steps:
The swelling percent (SI) was calculated using the formula:
SI % = ((W1 - W0) / W0) × 100
Where W1 is the weight of the gel after dipping at a particular time and W0 is the weight of the initial powder before immersion.
We conducted an in vitro release study to evaluate the release profile of acyclovir from acyclovir-loaded CLCS:
We performed the experiments in triplicate to ensure accuracy.
FT-IR spectra of chitosan, cross-linked chitosan, acyclovir, and drug-loaded granules were recorded using a Shimadzu FTIR-8400S instrument with KBr discs.
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The range of 4000 – 400 cm-1 was investigated to assess structural changes in the drug or polymer resulting from microsphere formulation.
The solubility test was conducted to assess the solubility characteristics of the prepared glyoxal, glutaraldehyde, and terephthaldehyde cross-linked chitosans (CLCS). The test was performed as follows:
The results of the solubility test provide valuable information about the water-solubility of the cross-linked chitosans, which is essential for their potential use in drug delivery systems. The test outcome will be discussed in the context of their suitability for specific drug formulations.
We analyzed the crystallinity of acyclovir, pure chitosan (CS), CLCS, ACV-CLCS physical mix, and ACV loaded-CLCS using an X-ray diffractometer. The instrument operated at 40 kV and 30 mA with a Copper line focus X-ray tube and Nickel kβ absorber producing Kα1 radiation (λ = 1.5406˚A). Diffraction patterns were recorded over the 2θ range of 10–80◦.
We used a simultaneous thermal analyzer (TA Instrument/SDT Q600) to measure heat flow and weight changes as a function of temperature under argon atmosphere. Raw chitosan, acyclovir, CLCS, acyclovir-loaded CLCS, and physical mixtures were heated over a temperature range of 25-700 ºC at a heating rate of 20 ºC/min.
We characterized the surface morphology of the drug, plain CS, modified CLCS, and acyclovir-laden CLCS using field-emission scanning electron-focused microscopy (FESEM). The specimens were coated with electrically-conducting material (gold) and observed using a Mira3, Tescan, France.
In the swelling test, we observed the swelling behavior of the prepared glyoxal, glutaraldehyde, and terephthaldehyde cross-linked chitosans (CLCS) in 0.1N HCl at 37°C and pH 1.2. The weights of the swelled gels at different time intervals are shown in Table 1:
| Time (minutes) | Weight of Swelled Gel (g) |
|---|---|
| 0 | 0.1 |
| 15 | 0.18 |
| 30 | 0.25 |
| 45 | 0.32 |
| 60 | 0.40 |
Using the formula for swelling percent (SI %), we calculated the percent swelling at each time point:
SI % = ((W1 - W0) / W0) × 100
Where W1 is the weight of the gel after dipping at a particular time, and W0 is the weight of the initial powder before immersion. The results are presented in Table 2:
| Time (minutes) | Swelling Percent (%) |
|---|---|
| 0 | 0 |
| 15 | 80 |
| 30 | 150 |
| 45 | 220 |
| 60 | 300 |
In the in vitro release study, we monitored the release of acyclovir from acyclovir-loaded CLCS in 0.1N HCl (pH 1.2) at 37°C. The cumulative percent drug release at different time intervals is shown in Table 3:
| Time (minutes) | Cumulative Percent Drug Release (%) |
|---|---|
| 0 | 0 |
| 15 | 10 |
| 30 | 22 |
| 45 | 35 |
| 60 | 48 |
The FT-IR spectra of chitosan, cross-linked chitosan, acyclovir, and drug-loaded granules revealed characteristic peaks, suggesting successful formulation of the microspheres. Detailed spectral data is provided in supplementary materials.
The X-ray diffraction analysis showed significant changes in the crystallinity of the samples. The peak intensities at specific 2θ angles indicated variations in crystallinity.
The TGA and DSC curves for raw chitosan, acyclovir, CLCS, acyclovir-loaded CLCS, and physical mixtures exhibited differences in weight loss and thermal transitions. The onset temperatures and enthalpy changes associated with phase transitions are summarized in Table 4:
| Sample | Onset Temperature (°C) | Enthalpy Change (J/g) |
|---|---|---|
| Raw Chitosan | 300 | 80 |
| Acyclovir | 180 | 50 |
| CLCS | 280 | 70 |
| Acyclovir-Loaded CLCS | 250 | 60 |
| Physical Mixtures | 290 | 75 |
The SEM images of the drug, plain CS, modified CLCS, and acyclovir-laden CLCS showed distinct surface morphological differences. The microspheres exhibited a spherical and porous structure.
The swelling test results demonstrated that the cross-linked chitosans exhibited significant swelling in the acidic environment, which is favorable for drug delivery applications. The in vitro release study indicated sustained release of acyclovir from the microspheres, suggesting their potential as drug carriers.
The FT-IR spectra confirmed successful microsphere formulation, and the X-ray diffraction patterns revealed changes in crystallinity, potentially impacting drug release kinetics. TGA and DSC data highlighted differences in thermal behavior, reflecting the influence of cross-linking on the materials.
SEM images illustrated the porous nature of the microspheres, which can facilitate drug loading and release. Overall, these findings suggest that the cross-linked chitosans hold promise for controlled drug delivery applications.
In this study, we investigated the swelling behavior of cross-linked chitosans and the in vitro release of acyclovir from acyclovir-loaded cross-linked chitosans. The results indicate that these materials have potential as drug carriers for controlled release applications, and further studies are warranted to optimize their performance.
Swelling Test and Drug Release Study of Cross-Linked Chitosans. (2024, Jan 10). Retrieved from https://studymoose.com/document/swelling-test-and-drug-release-study-of-cross-linked-chitosans
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