Group 076-10: Characterization of Bromelain Release from Calcium Alginate Matrices

Based on the results of the last batch of experiments, a new experiment was set up using higher bromelain levels in order to detect difference in absorbance using the spectroscopic equipment acquired.  Figure 1 shows Justin adding samples to a cuvette for testing. The higher concentration calibration curve is pictured below in figure 2. All of the concentrations were visible, proving that the detection of bromelain is possible using spectrophotometry.  Figure 1: Group member Justin Li conducting spectrophotometry tests Figure 2. Absorbance Calibration Curve From there the experiment was conducted once again with two varying densities: .5% wt and 1% wt alginate solution. The bromelain/alginate beads were placed in only 50cc's of water as opposed to 1000ccs.  This was done to increase the concentration of bromelain in solution so that it could be more easily detected by the equipment another strategy that was used to increase concentration was simply ...

This week, we focused on fabricating calcium alginate gel matrices containing bromelain.  Bromelain was added to distilled water and stirred before sodium alginate was mixed into the solution.  Sodium alginate concentrations of 1 wt% and 2 wt% were used.  The bromelain alginate solution was then cast into a 0.5 wt% CaCl 2 solution using a pipette.  Normally, droplets of the bromelain alginate solution fell from the pipette tip once the droplet reached sufficient mass (0.04 mg) that the force of gravity overcame the droplets’ cohesive force with the solution inside the pipette and the adhesive force with the pipette tip.  Early attempts to cast the 2 wt% alginate solution, resulted in cylindrical alginate structures since the viscosity of the solution resulted in long streams rather than discrete droplets.  This was avoided by manually separating the alginate solution from the pipette tip once it reached a desirable size.  Once the alginate bromelain s...

Our literature search revealed that protein concentration can be quantified by measuring absorbance at 280 nm.  Although considerable error can arise when measuring mixed protein samples, the concentration of pure proteins, such as bromelain, can be reliably and quickly determined via this method.   The goal for this week was to create a calibration curve for bromelain absorption at the reported peak of 280 nm.   Based on the recommended dose of 200 mg bromelain per meal and the average volume of a human stomach (roughly 1 L), a maximum concentration of 0.2 mg/mL was determined.  A standard was created by adding 2 mg of bromelain to 20 mL of distilled water, and serial dilutions were performed to create four more solutions with concentrations decreasing by a factor of 10.  A 1 wt% sodium alginate standard solution and 0.5 wt% CaCl2 standard solution were also prepared for baseline tests. Figure 1. Dan the pipetting expert Figure 2. Mike inspecting sa...

The group discussed the new direction of the project with our adviser last Friday, and it was recommended that that the multi-shell aspect be postponed for future work.  Therefore, the current project is focusing on controlling single stage release via established methods such as varying alginate concentration and surface area. The bromelain powder arrived this week, so the group decided to begin experimenting with incorporating it into alginate structures.  We discovered early on that mixing bromelain into a sodium alginate solution was difficult due to the inherent viscosity of the solution, so it was decided that bromelain should be dissolved in water before the addition of sodium alginate.   Figure 1. Sample absorbance spectra of proteins Based on our literature search, two methods for detecting bromelain concentration were considered for the experiment.  The presence of amino acids with aromatic rings in proteins results in a spectroscopic absorbance pe...

This week, the group moved forward with our new project idea. Besides refining the concept, the group made their first attempt at creating multilayered hydrogels. Figures 1 and 2 show multilayered hydrogels at 1 wt% and 1.5 wt% alginate, respectively.  Two distinguish between layers, contrasting food dyes were mixed with individual batches of sodium alginate solution.  The inner core was created by injecting  ≈ 0.5 mL of sodium 1 wt% sodium alginate into a 1 wt% CaCl 2  solution, forming a 4mm diameter sphere.  Subsequent layers were formed by dipping the cores in an alginate solution dyed a different color followed by the  CaCl 2   bath.  Preliminary findings found a positive correlation between dipping time and layer thickness up to a 3mm maximum. Upon another meeting with the group advisor, it was determined that the project was a sound one but could use some simplification. After further discussion, the group came to the conclusion that it...

After some discussion with the group advisor, it was determined that the best way to proceed was to find a new topic for the project and more or less start over. The Group and advisor found a new project idea based on basic diffusion and alginate shells. Essentially, the overall capsule will have two shells of alginate; an outer shell and an inner shell. Between the outer shell and the inner shell there will be a dense region of alginate containing calcium carbonate, which, upon ingestion, will very quickly be released into the stomach via simple diffusion. Within the inner shell, there will be a less dense region of alginate containing bromelain, which will gradually release from the inner shell to the outer shell and then to the stomach, also via simple diffusion. The structure of the capsule is shown below in figure 1. The reason bromelain will be used is that bromelain breaks down proteins very well. Therefore, the group will create a drug that could be used by ...

This week the group’s discussions and planning were primarily focused upon the testing of the magnetic field induced medication release. Specifically, the group spent a good amount of time determining necessary materials to do this and then ordered them. Several new items were ordered including 5 pounds of iron(II,III) oxide nanoparticles (30 micron), and clear plastic tubing. An extra few days was allotted for the planned arrival of these materials, due to the processing speed of Drexel University’s postal delivery service. Figure 1. Test setup and measurement These materials were ordered with a specific testing strategy in mind. First, the group considered the scale that everything aspect of the experiment (tube size, electric/magnetic field power) would have to be since the capsule size would have to be enlarged in order to prototype. It was determined that a 3/4 inch inside diameter tube would be adequate. Figure 1 shows the step by step function of the proposed test se...