Channel Responses for the Molecule Release from Spherical Homogeneous Matrix Carriers

TL;DR

This paper models the diffusion-based channel response of spherical matrix drug carriers in molecular communications, providing analytical tools to evaluate release dynamics and compare with idealized models, with applications to therapeutic drug delivery.

Contribution

It introduces a detailed channel response model for spherical matrix carriers, including criteria for dominant release or channel effects, and offers closed-form approximations for practical regimes.

Findings

Derived the channel response for spherical matrix carriers.

Compared matrix models with point and transparent sphere models.

Provided closed-form approximations for limiting regimes.

Abstract

Molecular communications is a promising framework for the design of controlled-release drug delivery systems. Under this framework, drug carriers, diseased cells, and the channel are modeled as transmitters, absorbing receivers, and diffusive channel, respectively. In this paper, we investigate diffusion-based spherical matrix-type drug carriers, which are employed in medical applications. In a matrix carrier, the drug molecules are dispersed in the matrix core and diffuse from the inner to the outer layers of the carrier once immersed in a dissolution medium. We derive the channel response of the matrix carrier transmitter for an absorbing receiver and compare our results with commonly used point and transparent spherical transmitters to highlight the necessity of considering practical models. Furthermore, we derive a criterion for evaluating whether the release process or the channel dynamics are more important for the characteristics of the channel response of a drug delivery system. For the limiting regimes, where only the release process or the channel determine the behavior of the end-to-end system, we propose closed-form approximations for the channel response. Finally, we investigate the channel responses for the release of common therapeutic drugs, e.g., doxorubicin, from a diblock copolymer micelle acting as drug carrier.