Fluorescence-Based Nano-Oxygen Particles for Spatiometric Monitoring of Cell Physiological Conditions

Abstract

Closed-loop artificial pancreas systems have recently been proposed as a solution for treating stage I diabetes by reproducing the function of the pancreas. However, there are many unresolved issues associated with their development, including monitoring and controlling oxygen, immune responses, and the optimization of glucose, all of which need to be monitored and controlled to produce an efficient and viable artificial organ that can become integrated in the patient and maintain homeostasis. This research focused on monitoring the oxygen concentration, specifically achieving this kinetically as the oxygen gradient in an artificial pancreas made of alginate spheres containing islet cells. Functional nanoparticles (NPs) for measuring the oxygen gradient in different hydrogel cellular environments using fluorescence-based (F) microscopy were developed and tested. By the ester bond, a linker Pluronic F127 was conjugated with a carboxylic acid-modified polystyrene NP (510 nm). A hydrophilic/hydrophobic interaction between the commercially available oxygen-sensitive fluorophore and F127 results in fluorescence-based nano-oxygen particles (FNOPs). The in-house synthesized FNOP was calibrated inside electrosprayed alginate-filled hydrogels and demonstrated a good broad dynamic range (2.73-22.23) mg/L as well as a resolution of -0.01 mg/L with an accuracy of ±4%. The calibrated FNOP was utilized for continuous measuring of the oxygen concentration gradient for cell lines RIN-m5F/HeLa for more than 5 days in alginate hydrogel spheres in vitro.

Introducing Aggregation-Induced Emission to Students by Visual Techniques Demonstrating Micelle Formation with Thin-Layer Chromatography

“…In this present experiment, students prepared micelles by F127 and encapsulated 2­(TPA-O)-TPE into the micelle’s core. This solution consists of F127 micelles due to the driving force of the hydrophobic effect. − Meanwhile, the water-insoluble 2­(TPA-O)-TPE was spontaneously aggregated into the micelle’s core. Finally, nanoscale objects were formed, and stable emulsified solutions were obtained (Figure ).…”

Biosensors to Monitor Cell Activity in 3D Hydrogel-Based Tissue Models

“…Higher cell viability in the external areas of the hydrogel compared to the inner region was found, due to the establishment of O 2 gradients through the hydrogel, attributable to the well-known gas limitations in diffusion. Moreover, results reported first a decrease in O 2 concentration within the hydrogel due to the cells consumption, and then a reverse increased analyte tension, probably due to the exponential decay of the cellular density within the gel over time [165].…”

Impact of a Desmoplastic Tumor Microenvironment for Colon Cancer Drug Sensitivity: A Study with 3D Chimeric Tumor Spheroids

“…The FNOP will report hypoxia with red fluorescence emission (>610 nm), and the fluorescence intensity reversely correlates to oxygen concentration. 42 The z-intensity profile was measured along the specified marking line (green color) (n = 3). The z-stacks were divided into 10 μm slices, and the average of the 10 slices and 100 intensity points within the 100 μm region was specified as in the previous study.…”

“…The z-stacks were divided into 10 μm slices, and the average of the 10 slices and 100 intensity points within the 100 μm region was specified as in the previous study. 42 The detailed hypoxic measurement procedure is mentioned in Supporting Information Section S1.8.…”