Paper BI+PB-TuP2
Quantitative Sensing of Pancreatic Enzymes using Gelatin

Tuesday, November 8, 2016, 6:30 pm, Room Hall D

We present an investigation of gelatin film response to an array of pancreas-specific enzymes using a Quartz Crystal Microbalance (QCM) system. In fluids secreted from the pancreas into the upper small intestine, highly concentrated enzymes (α-amylase, trypsin, and lipase) are mixed to complete digestion of partially broken-down materials entering from the stomach. Sensors, such as that illustrated in Fig 1, are utilizing biomaterials such as gelatin, as it can be used to enter the body due to its biocompatibility and tailorability both chemically and structurally. Gelatin is known to be highly sensitive to degradation by trypsin, one of the aforementioned enzymatic pancreas biomarkers, thereby offering potential to indirectly monitor trypsin levels [1]. The composition of pancreatic fluid is a biomarker in testing exocrine function of the pancreas, a process often involving invasive procedures toward quantifying losses in enzyme levels [2]. However, its interactions with other interfering enzymes such as lipase or α-amylase have not been studied. While these enzymes are believed to cleave specific to bonds not found in gelatin, it is critical to be able to determine how these non-specific enzymes impact the signals produced when gelatin interacts with specific enzymes, i.e. trypsin, when they are each in the media.

In this work, we utilize a QCM system in sensing the mass change of gelatin films deposited onto standard crystals with gold electrodes. Films are subjected to a constant flow rate of buffer before introducing pancreatic enzymes in the setup illustrated in Fig 2. After system stabilization under buffer flow, material loss is quantified from the surface of the crystal. For trypsin, as expected, we observe degradation in a concentration-dependent manner, shown in Fig. 3. With either lipase or α-amylase, however, we observe no change, as illustrated in the top of Fig 4. After rinsing with buffer, we reintroduce trypsin in combination with each enzyme to determine if the presence of nonspecific enzymes affected the sensitivity of the gelatin to proteolytic activity, shown in the bottom of Fig 4. Digestion rates are found to decrease by ­­­­­83% and 77% with exposure to lipase or α-amylase, respectively, indicating a decrease in gelatin sensitivity to trypsin in the presence of these enzymes. The next phase in this work will be to combine all three enzymes to further model pancreatic juices. This work emphasizes the necessity in characterizing gelatin’s response to other enzymes in understanding its sensitivity and specificity in the digestive environment, leading the avenue for devices designed to monitor gastrointestinal health.