Flow-driven translocation of comb-like copolymer vesicles through a nanochannel: the influence of nanochannel size and vesicle membrane thickness

Abstract

We employed a hybrid simulation approach that combines a lattice-Boltzmann (LB) method for simulating fluid flow with a molecular dynamics (MD) model for the polymers to investigate the translocation of comb-like copolymer vesicles driven by fluid flow through a nanochannel. Our findings reveal that the relationship between the critical flow rate (Q_c) and the nanochannel diameter (D_x) can be divided into two distinct stages. In the first stage, when D_v/D_x is greater than 1.5 (D_v represents the diameter of the vesicle), the vesicles translocate through a fragmentation mode. This involves the formation of split spherical micelles and worm-like micelles, following the relationship Q_c∼ −D_x. In the second stage, when D_v/D_x falls below 1.5, the vesicles can be compressed into stretched shapes or experience little to no change during passage. This mode of translocation is referred to as intact translocation, and the relationship changes to Q_c∼ 1/D_x. We also found that for vesicles of the same size, increasing the membrane thickness by extending the backbone length of assembled comb-like copolymers significantly raises the critical flow rate. Additionally, when comparing comb-like vesicles with block copolymer vesicles of identical size and membrane thickness, the critical flow rate for block copolymer vesicles is approximately 30 times greater than that of comb-like vesicles. These insights have important implications for the design and optimization of comb-like copolymer vesicle systems used in drug delivery, gene therapy, and nanotechnology applications.