Investigating the effects of solution viscosity on the stability and success rate of SECCM imaging

Due to the capability of simultaneously detecting the morphology and electrochemical information of samples and limiting the electrochemical reaction to a range approximately the size of the inner diameter of the pipette tip opening, scanning electrochemical cell microscopy (SECCM) enables higher precision local electrochemical measurement and surface material delivery and has been demonstrating unique advantages and broad application prospects. However, the meniscus droplet at the pipette tip of SECCM is equivalent to the opening radius of the pipette tip, which is usually tens of nanometers to hundreds of nanometers. The tiny meniscus droplet makes it susceptible to evaporation and crystallization, which increases the likelihood of the pipette colliding with the sample during the scanning process, resulting in the failure of scanning. In this paper, the influence of solution viscosity on the shape variation of the droplet at the tip during the movement of the pipette of SECCM was studied by finite element analysis. It is proved that the increase of solution viscosity is helpful in reducing the shape variation of the droplet at the tip during the movement of the pipette. Then scanning experiments were carried out using a flat Au substrate and Au substrates with rounded triangle and rounded rectangular convex structures as the samples. According to the experimental results, increasing solution viscosity improves scanning success rates and scanning quality and effectively lowers the MSE of the scanning results. The experimental results also show that SECCM can image at a higher speed when the solution's viscosity increases since the deformation of the droplet at the tip is less than with a typical solution.

Hydroelectric actuator for 3-dimensional analysis of electrophoretic and dielectrophoretic behavior of cancer cells; suitable in diagnosis and invasion studies

Cancer is a cellular-based disease, so cytological diagnosis is one of the main challenges for its early detection. An extensive number of diagnostic methods have been developed to separate cancerous cells from normal ones, in electrical methods attract progressive attention. Identifying and specifying different cells requires understanding their dielectric and electric properties. This study evaluated MDA-MB-231, HUVEC, and MCF-10A cell lines, WBCs isolated from blood, and patient-derived cell samples with a cylindrical body with two transparent FTO (fluorine-doped tin oxide) plate electrodes. Cell mobility rates were recorded in response to these stimuli. It was observed that cancer cells demonstrate drastic changes in their motility in the presence and absence of an electric field (DC/AC). Also, solution viscosity's effect on cancer cells' capturing efficacy was evaluated. This research's main distinguished specification uses a non-microfluidic platform to detect and pathologically evaluate cytological samples with a simple, cheap, and repeatable platform. The capturing procedure was carried out on a cytological slide without any complicated electrode patterning with the ability of cytological staining. Moreover, this platform successfully designed and experimented with the invasion assay (the ability of captured cancer cells to invade normal cells).

Intraductal pressure in experimental models of acute and chronic pancreatitis in mice

BACKGROUND/OBJECTIVES

Pancreatic intraductal pressure is related to the development of pancreatitis, including post-ERCP (endoscopic retrograde cholangiopancreatography) pancreatitis. In this study, we investigate pancreatic intraductal pressure in various mouse models of acute and chronic pancreatitis.

METHODS

Post-ERCP pancreatitis was induced by retrograde infusion of normal saline or radiocontrast at the constant rate of 10 or 20 μL/min. Obstructive pancreatitis was induced by ligation of the pancreatic duct followed by a single injection of caerulein and the changes of intraductal pressure were recorded in day 3 for obstructive acute pancreatitis and day 14 for obstructive chronic pancreatitis. Non-obstructive pancreatitis was induced by repetitive intraperitoneal injections of caerulein. The changes of intraductal pressure were recorded right after the last caerulein injection for non-obstructive acute pancreatitis and after the completion of 4-week caerulein injections for non-obstructive chronic pancreatitis.

RESULTS

Elevated pancreatic intraductal pressure was observed in both normal saline and radiocontrast infusion groups and was furtherly indicated that was positively correlated with the viscosity of solution but not genders. In the models of obstructive pancreatitis, a rise in intraductal pressure was observed in both acute and chronic pancreatitis; whereas in the models of non-obstructive pancreatitis, a rise in intraductal pressure was only observed in chronic, but not acute pancreatitis.

CONCLUSIONS

During ERCP, the elevations in pancreatic intraductal pressure are induced by increasing rate or viscous solution of infusion. During different forms of experimental acute and chronic pancreatitis, obstructive or non-obstructive etiologies of pancreatitis also induces the elevations in pancreatic intraductal pressure.

Investigation of the batch-to-batch inconsistencies of Collagen in PCL-Collagen nanofibers

The application of tissue engineered constructs is an approach in regenerative therapies to support regeneration of damaged muscular tissue. Therefore the development of highly aligned electrospun scaffolds based on polycaprolactone (PCL) and collagen enables a versatile development towards tailor made applications. However, the application of natural polymers like collagen brings the risk of batch-to-batch inconsistencies, which influence the reproducibility of the electrospinning process. Aligned PCL-Collagen nanofibers were fabricated via electrospinning using benign solvents. The spinnability of different collagen batches and polymer concentrations in diluted acetic acid as solvent was investigated. Furthermore spinning parameters and fiber morphology were investigated in order to determine the most stable spinning conditions and analyze the batch-to-batch variations. Finally the effect of the solution temperature and the time of pure collagen in solution were investigated, to complete the analysis of the influences on the spinning behavior.