Development of Dissipative Particle Dynamics framework for modeling hydrogels with degradable bonds

Abstract

Controlled degradation of hydrogels enables several applications of these materials, including controlled drug and cell release applications and directed growth of neural networks. These applications motivate the need of a simulation framework for modeling controlled degradation in hydrogels. We develop a Dissipative Particle Dynamics (DPD) framework for hydrogel degradation. As a model hydrogel, we prepare a network formed by end-linking tetra-arm polyethylene glycol precursors. We model bond breaking during degradation of this hydrogel as a stochastic process. The fraction of degradable bonds follows first order degradation kinetics. We characterize the rate of mass loss during degradation process.

Controlling Degradation and Erosion of Polymer Networks: Insights from Mesoscale Modeling

“…For a number of the polymer networks undergoing controlled photodegradation, the degradation rate constants are within the range of ,,,, 1 s –1 to 10 –3 s –1 , that is, the degradation occurs orders of magnitude slower than the characteristic diffusion times on the relevant length scales . Hence, low degradation rates are chosen in our simulations, ensuring that our system remains in a kinetically limited regime. , …”

“…Herein, we use τ r = 10Δ t , similarly to the choice of reaction time step in previous DPD simulations of various reactive systems. ,,− At each reaction time step a random number is generated for each degradable bond; if this number is lower than P , the bond is broken. We recently modified the mSRP framework to switch the additional forces (corresponding to the pseudo-beads) off upon bond breaking . In our simulations, the time evolution of the fraction of degradable bonds intact at a given time, p ( t ), accurately reproduces first-order degradation reaction kinetics p = exp­(− kt ) with the rate constant k = P /τ r ; no fitting is required .…”

“…In our simulations, the time evolution of the fraction of degradable bonds intact at a given time, p ( t ), accurately reproduces first-order degradation reaction kinetics p = exp­(− kt ) with the rate constant k = P /τ r ; no fitting is required . For a number of the polymer networks undergoing controlled photodegradation, the degradation rate constants are within the range of ,,,, 1 s –1 to 10 –3 s –1 , that is, the degradation occurs orders of magnitude slower than the characteristic diffusion times on the relevant length scales . Hence, low degradation rates are chosen in our simulations, ensuring that our system remains in a kinetically limited regime. , …”

“…We use dissipative particle dynamics (DPD) − to model these complex systems. DPD is a mesoscale approach utilizing soft repulsive interactions between the beads representing clusters of atoms; this approach has been widely used to model a variety of complex systems, − including dynamics of hydrogels in various environments. − To overcome unphysical topological crossings of bonded polymer chains, we recently adapted a modified segmental repulsive potential (mSRP) formulation to model gels with degradable bonds …”

In Silico Prediction of Food Properties: A Multiscale Perspective

“…A general methodology has been developed to devise interaction parameters in DPD models from arbitrary dynamics (at atomistic scale or from another coarse-grained simulation). Eriksson et al (2009) The applications are numerous, from evaluating the permeability of the skin to chemicals Otto et al (2018) to digestion phenomena Palkar et al (2020) well as the lack of standard food structures to develop or test algorithms.…”