Microfluidic-Assisted Engineering of Quasi-Monodisperse pH-Responsive Polymersomes toward Advanced Platforms for the Intracellular Delivery of Hydrophilic Therapeutics

Abstract

The extracellular and subcellular compartments are characterized by specific pH levels that can be modified by pathophysiological states. This scenario encourages the use of environmentally responsive nanomedicines for the treatment of damaged cells. We have engineered doxorubicin (DOX)-loaded pHresponsive polymersomes using poly(We demonstrate that, by taking advantage of the microfluidic technology, quasi-monodisperse assemblies can be created. This feature is of due relevance because highly uniform nanoparticles commonly exhibit more consistent biodistribution and cellular uptake. We also report that the size of the polymer vesicles can be tuned by playing with the inherent mechanical parameters of the microfluidic protocol. This new knowledge can be used to engineer size-specific nanomedicines for enhanced tumor accumulation if the manufacturing is performed with previous knowledge of tumor characteristics (particularly the degree of vascularity and porosity). The pHdependent DOX release was further investigated evidencing the ability of polymersome to sustain encapsulated hydrophilic molecules when circulating in physiological environment (pH 7.4). This suggests nonrelevant drug leakage during systemic circulation. On the other hand, polymersome disassembly in slightly acid environments takes place enabling fast DOX release, thereby making the colloidal carriers highly cytotoxic. These features encourage the use of such advanced pH-responsive platforms to target damaged cells while preserving healthy environments during systemic circulation.

Self-Assembly of PEG-b-PTMC Copolymers: Micelles and Polymersomes Size Control

“…flow ratios between solutions and overall total flow rate). 22,[25][26][27][28] This permits reproducibility which is absolutely necessary for the development of Ps as drug delivery systems.…”

Mastering the Tools: Natural versus Artificial Vesicles in Nanomedicine

“…They were able to reduce the sizes of the polymersomes down to about 50 nm by increasing the flow rate of the water phase up to 200 µL min −1 (Figure 4G). Furthermore, they successfully loaded them with DOX, permitting a pH-responsive delivery to tumor cells (B16F10 and 4T1) at similar levels compared to free administrated DOX [155] (Figure 4H). As in the case of microfluidic systems, in 2018, the inkjet printing technologies [156] were employed for emulsion preparations, [157][158][159] and implemented for vesicle assembly, with high reproducibility and size control.…”

“…In another report, Albuquerque et al, in 2019, prepared pH-responsive polymersomes using poly([N-(2-hydroxypropyl)]methacrylamide)-b-poly [2-(diisopropylamino)ethyl methacrylate]-block-copolymers (PHPMAm-b-PDPAn). [155] The authors realized micromixers based on microfluidics chip ( Figure 4F). They were able to reduce the sizes of the polymersomes down to about 50 nm by increasing the flow rate of the water phase up to 200 µL min −1 (Figure 4G).…”

“…Reproduced with permission. [155] Copyright 2019, American Chemical Society. I) Scheme for the inkjet printing production of individual liposome vesicles.…”

“…Indeed, given their higher flexibility in production and easier functionalization, polymersomes can be envisaged as an advantageous and cheaper alternative to liposomes. Extracellular vesicles + Difficult massive production and purification; biomolecules as only building blocks; limited tunability of the physicochemical properties [ 87,240] +++ Generally safe; extraction from biological sources with high biocompatibility [80,83] ++ Excellent loading of biomolecules; challenging loading of synthetic molecules; good delivery efficiency;rapid clearance [ 186,187] Liposomes ++ Easy production and purification; pre-and postsynthetic functionalization; tunable physicochemical properties [ 124,161] +++ Generally safe, unless modified with charged phospholipids; similar composition to EVs, but without cell-mediated modifications [103,213] ++ Good natural and synthetic molecules loading; preassembly and postassembly loading; good delivery efficiency; tunable clearance properties [ 198,199] Polymersomes +++ Customizable massive production; pre-and postsynthetic functionalization; tunable physicochemical properties [ 136,155] + Possible accumulations in the body; possibility to introduce biodegradable polymers [229,230] + Preassembly and postassembly loading; cell uptake dependent on the vesicle and cell membrane characteristic; tunable clearance properties [ 222,224]…”