Nanogel Degradation at Soft Interfaces and in Bulk: Tracking Shape Changes and Interfacial Spreading

Abstract

Via mesoscale simulations, we characterize the process of controlled degradation of nanogels suspended in a single solvent and those adsorbed at the liquid−liquid interface between two incompatible fluids. Controlled degradation is of interest since it can be used to dynamically tailor size, shape, and transport properties of these soft particles. For the nanogels adsorbed at the liquid−liquid interfaces, controlled degradation can provide a means to dynamically tailor interfacial properties on the nanoscale. To characterize the degradation process, we track the structural characteristics of the remnant nanogel, such as its radius of gyration and shape anisotropy, and spatiotemporal distribution of the broken-off fragments. We use the dissipative particle dynamics approach with an adapted form of the modified segmental repulsive potential. We identify the reverse gel point and characterize the scaling of this point with the finite number of polymer precursors in the system. Furthermore, we characterize the effects of polymer−solvent interactions on the evolution of shape and effective size of the nanogel during the degradation process. We show that for the nanogel adsorbed onto the liquid−liquid interface, the extent of spreading is controlled by the relative extent of degradation. We demonstrate that depending on the properties of the soft interface, broken-off fragments can either disperse into one of the phases or adsorb onto the interface, enhancing the interfacial coverage and controlling interfacial properties on the nanoscale. Our study provides insights into using controlled degradation to dynamically tune shapes of nanocarriers and nanoscale topography at the liquid−liquid interfaces.

Mesoscale modeling of random chain scission in polyethylene melts

“…We model bond breaking as a stochastic process, similar to the approaches previously used in DPD and molecular dynamics studies of reactive polymeric systems [40,41,43,64,65]. During each reaction time step τ r , which is taken tenfold [40,41,43,52] of the DPD timestep, ∆t, a random number is generated for each degradable bond [45,47,48,52]. If this number is lower than the chosen reaction probability P, the bond is broken.…”

“…Recent developments and applications of DPD can be found in recent reviews by Español and Warren [37] and Santo and Neimark [38]. In particular, DPD has been used to model a range of reactive polymer systems [39][40][41][42][43][44][45][46][47][48][49][50]. A modified segmental repulsive potential (mSRP) introduced by Sirk et al [51] effectively minimizes topological violations or unphysical crossing of polymer chains, addressing this well-known limitation of the standard DPD approach.…”

Current Advances in Stimuli-Responsive Hydrogels as Smart Drug Delivery Carriers

“…(1) an increased surface-area-to-volume ratio, which enhances the drug loading amount and release efficiency [27]; (2) controlled interfacial properties and the ability to modify or functionalize particle interfaces [28,29]; (3) a suitable nanoscale size, which enables nanogels to penetrate biological barriers and reach specific target sites in the body, such as tumors, facilitating cell uptake and tumor penetration [30]; (4) stimuli-responsive behaviors that can be controlled by selecting constituent polymer and crosslinker components, allowing for a desired response at the site of action, and enabling nanogels to actively participate in the intended function of the carrier system, rather than being passive carriers of their cargo [31];…”

“…The redu in hydrogel particle size to the nanoscale imparts several unique properties to nano including precise control over their interfacial properties, improved mechanical stre and enhanced responsiveness to external stimuli. Specifically, these properties en pass: (1) an increased surface-area-to-volume ratio, which enhances the drug loa amount and release efficiency [27]; (2) controlled interfacial properties and the abil modify or functionalize particle interfaces [28,29]; (3) a suitable nanoscale size, whic ables nanogels to penetrate biological barriers and reach specific target sites in the b such as tumors, facilitating cell uptake and tumor penetration [30]; (4) stimuli-respo behaviors that can be controlled by selecting constituent polymer and crosslinker co nents, allowing for a desired response at the site of action, and enabling nanogels t tively participate in the intended function of the carrier system, rather than being pa carriers of their cargo [31]; (5) improved stability of drugs and increased circulation in the bloodstream due to their small size, which can improve drug efficacy [32]; an enhanced biocompatibility and biodegradability due to the small size, which reduce icity [33].…”