Chronic methamphetamine use, a widespread drug epidemic, has been associated with cardiac morphological and electrical remodeling, leading to the development of numerous cardiovascular diseases. While methamphetamine has been documented to induce arrhythmia, most results originate from clinical trials from users who experienced different durations of methamphetamine abuse, providing no documentation on the use of methamphetamine in standardized settings. Additionally, the underlying molecular mechanism on how methamphetamine affects the cardiovascular system remains elusive. A relationship was sought between cardiotoxicity and arrhythmia with associated methamphetamine abuse in zebrafish to identify and to understand the adverse cardiac symptoms associated with methamphetamine. Zebrafish were first treated with methamphetamine 3 times a week over a 2-week duration. Immediately after treatment, zebrafish underwent electrocardiogram (ECG) measurement using an in-house developed acquisition system for electrophysiological analysis. Subsequent analyses of cAMP expression and Ca²⁺ regulation in zebrafish cardiomyocytes were conducted. cAMP is vital to development of myocardial fibrosis and arrhythmia, prominent symptoms in the development of cardiovascular diseases. Ca²⁺ dysregulation is also a factor in inducing arrhythmias. During the first week of treatment, zebrafish that were administered with methamphetamine displayed a decrease in heart rate, which persisted throughout the second week and remained significantly lower than the heart rate of untreated fish. Results also indicate an increased heart rate variability during the early stage of treatment followed by a decrease in the late stage for methamphetamine-treated fish over the duration of the experiment, suggesting a biphasic response to methamphetamine exposure. Methamphetamine-treated fish also exhibited reduced QTc intervals throughout the experiment. Results from the cAMP and Ca²⁺ assays demonstrate that cAMP was upregulated and Ca²⁺ was dysregulated in response to methamphetamine treatment. Collagenic assays indicated significant fibrotic response to methamphetamine treatment. These results provide potential insight into the role of methamphetamine in the development of fibrosis and arrhythmia due to downstream effectors of cAMP.

Over the past two decades, additive manufacturing has advanced significantly, enabling rapid fabrication of functional components across various applications. In medical devices, it has been used for prototyping, prosthetics, drug delivery platforms, and more recently, tissue scaffolding. However, current technologies face challenges, particularly in depositing conformal layers over curved surfaces. This study introduces a novel multi-nozzle extrusion printer concept designed to deposit soft gel layers onto curved surfaces. A custom clearance locking mechanism enhances the printer’s ability to achieve conformal coatings on both flat and curved substrates. We investigate key deposition parameters, including displacement volume and nozzle configuration, while comparing two deposition sequences: “Press and Express” and “Express and Press”. Our results demonstrate that the “Express and Press” technique yields more uniform, merged conformal layers than the “Press and Express” method. This technology holds promise for further refinement and potential applications in tissue engineering.

Electrodeposited iridium oxide (IrOx) pH sensors are gaining interest in numerous biomedical applications, attributed to their superior accuracy, straightforward fabrication, and compatibility with other microfabrication processes. However, the pH sensing range and stability of these sensors have been long-entrenched challenges to control. In this study, we explored the sensor’s behavior under pH conditions beyond its typical sensing range, unearthing potential correlations between the sensing range and other influential factors. Based on these findings, we proposed and implemented a practical method to manipulate the sensing range to designated pH regions. This methodology significantly expanded the sensor’s applicability to encompass extreme acidic or basic environments. A series of investigations revealed that, under such severe conditions, the sensor’s stability—as quantified by drift—could be enhanced more than tenfold posttreatment. Moreover, other stability metrics, including linearity and hysteresis, exhibited notable improvements through this technique, as validated by titration tests in the extended pH sensing ranges. This research offers meaningful insights and a promising approach to enhance the sensing range and stability of electrodeposited IrOx pH sensors, thereby potentially progressing their practical application in biomedical domains.