Deswelling Dynamics of Thermoresponsive Microgel Capsules and Their Ultrasensitive Sensing Applications: A Mesoscopic Simulation Study

Abstract

Thermoresponsive microgels with a hollow capsule architecture have been widely used in drug delivery and molecular encapsulation, and their efficacy is contingent on the internal structure in the deswelling dynamics process. Despite a large number of experimental studies on microgels, proper theoretical methods based on an individual microgel capsule are still a few because of the complexity of the microgels. Herein, we first propose a novel methodology to investigate the structural properties and deswelling dynamics of microgel capsules by integrating a temperature-dependent Morse potential with Langevin dynamics simulation. Different properties, including volume phase transition temperature, temperature-dependent diameter, and structural morphologies of individual microgels, are assessed to rationalize our simulation method, and a good agreement between simulation predictions and experimental observations has been obtained. Depending on the system temperature, the morphological transition of three regimes in the shell structure is identified: scattered nanogels, progressively porous sponge gels, and dense ribbonlike gels. The temperature-switchable sensors composed of microgel capsules on the substrates are devised, which exhibit tunable reflectivity or thickness by simply varying the system temperature. Our mesoscale results provide helpful insights into the transient structure within the networked microgels and the design of smart polymeric nanomaterials, such as biosensors, drug delivery systems, and actuators.

Mechanochemical Cellular Membrane Internalization of Nanohydrogels: A Large-Scale Mesoscopic Simulation

“…Herein, we focus on the tetrafunctional crosslinker, which crosslinks four polymer chains, and it is modeled as a single particle. The nanohydrogel structure is constructed by a similar method as reported by Richtering et al ; it also can be found in our previous studies. , Through repeating an ideal diamond cubic crystal structure, the fully stretched linear chains with equal lengths are connected by a tetrafunctional crosslinker, and then, it can be tailored into the targeted geometry. Some literature has demonstrated that this model can describe the general structure–property relations of temperature-dependent swelling dynamics and surface pressure of microgels. ,, Owing to the crystalline order effects, it was found that this model just can compare the form factor with a fuzzy sphere model at small wave vectors rather than at intermediate scales. , Herein, we focus on swelling nanohydrogels under good solvent conditions, whose diameters are lower than 30 nm (see Table S1).…”

“…The nanohydrogel structure is constructed by a similar method as reported by Richtering et al; 57 it also can be found in our previous studies. 58,59 Through repeating an ideal diamond cubic crystal structure, the fully stretched linear chains with equal lengths are connected by a tetrafunctional crosslinker, and then, it can be tailored into the targeted geometry. Some literature has demonstrated that this model can describe the general structure−property relations of temperature-dependent swelling dynamics and surface pressure of microgels.…”

Interfacial assembly of anisotropic core-shell and hollow microgels

“…[35][36][37] This result is reproduced in a fairly wide range of interaction parameters as well as the flexibility of the subchains. 38,39 However, following such strategy one could notice, that simulation of the hollow ellipsoidal microgels failed and could not reproduce the experimental observations. 34 In particular, different trends of the shape/size evolution of the shell and the void upon collapse above their volume phase transition temperature (VPTT) are observed or extra flattening of the microgel at the interfaces is detected.…”

pH-Responsive Hollow Polymeric Microspheres from Irradiated Cyclic Ether Aqueous Solution

“…Stimuli-responsive hollow particles, especially hollow micro-sized or nano-sized spheres, continue to attract major interest because they have wide potential applications in fields such as dye precipitation [1], catalysis [2,3], sensors [4][5][6], and especially controlled delivery systems [7][8][9][10]. Early studies on hollow polymeric microspheres were conducted by Caruso et al [11].…”