Real-time Ratiometric Imaging of Micelles Assembly State in a Microfluidic Cancer-on-a-chip

The performance of supramolecular nanocarriers as drug delivery systems depends on their stability in the complex and dynamic biological media. After administration, nanocarriers are challenged by confronting different barriers such as shear stress and proteins present in blood, endothelial wall, extracellular matrix and eventually cancer cell membranes. While early disassembly will result in a premature drug release, extreme stability of the nanocarriers can lead to poor drug release and low efficiency. Therefore, comprehensive understanding of the stability and assembly state of supramolecular carriers in each stage of delivery is a key factor for the rational design of these systems. One of the key challenges is that current 2D in vitro models do not provide exhaustive information, as they do not fully recapitulate the 3D tumor microenvironment. This deficiency of the 2D models complexity is the main reason for the differences observed in vivo when testing the performance of supramolecular nanocarriers. Herein, we present a real-time monitoring study of self-assembled micelles stability and extravasation, combining spectral confocal microscopy and a microfluidic tumor-on-a-chip. The combination of advanced imaging and a reliable organ-on-a-chip model allow us to track micelle disassembly by following the spectral properties of the amphiphiles in space and time during the crucial steps of drug delivery. The spectrally active micelles were introduced under flow and their position and conformation followed during the crossing of barriers by spectral imaging, revealing the interplay between carrier structure, micellar stability and extravasation. Integrating the ability of the micelles to change their fluorescent properties when disassembled, spectral confocal imaging and 3D microfluidic tumor blood vessel-on-a-chip, resulted in the establishment of a robust testing platform, suitable for real-time imaging and evaluation of supramolecular drug delivery carriers stability.