Magnetic actuated pH-responsive hydrogel-based soft micro-robot for targeted drug delivery

Abstract

For drug delivery in cancer therapy, various stimuli-responsive hydrogel-based micro-devices have been studied with great interest. Here, we present a new concept for a hybrid actuated soft microrobot targeted drug delivery. The proposed soft microrobot consists of a hydrogel bilayer structure of 2-hydroxyethyl methacrylate (PHEMA) and poly (ethylene glycol) acrylate (PEGDA) with iron (II, III) oxide particles (Fe 3 O 4 ). The PHEMA layer as a pH-responsive gel is used for a trapping and unfolding motion of the soft microrobot in pH-varying solution, and the PEGDA-with-Fe 3 O 4 layer is employed for the locomotion of the soft microrobot in the magnetic field. The bilayer soft microrobot was fabricated by a conventional photolithography procedure and its characteristics were analyzed and presented. To evaluate the trapping performance and the motility of the soft microrobot, test solutions with different pH values and an electromagnetic actuation (EMA) system were used. First, the soft microrobot showed its full trapping motion at about pH 9.58 and its unfolding motion at about pH 2.6. Second, the soft microrobot showed a moving velocity of about 600 μm s −1 through the generated magnetic field of the EMA system. Finally, we fabricated the real anti-cancer drug microbeads (PCL-DTX) and executed the cytotoxicity test using the mammary carcinoma cells (4T1). The viability of the 4T1 cells treated with the proposed microrobot and the PCL-DTX microbeads decreased to 70.25±1.52%. The result demonstrated that the soft microrobot can be moved to a target position by the EMA system and can release a small amount of beads by the pH variation and the robot exhibited no toxicity to the cells. In the future, we expect that the proposed soft microrobot can be applied to a new tumor-therapeutic tool that can move to a target tumor and release anti-tumor drugs.

Contest-Driven Soft-Robotics Boost: The RoboSoft Grand Challenge

“…This discipline is steeply growing, and from the seminal review paper of Trivedi et al (2008) the field was subject to several evolutions; to date, the most recent review paper on soft robotics (Rus and Tolley, 2015) identifies four possible application domains for soft robots: locomotion, manipulation, wearable, and soft cyborgs. This review agrees with our survey on the most relevant domains influenced by soft robotic, which identified three niches: (1) the terrestrial locomotion, where a great number of bio-inspired (Belanger et al, 2000;Mezoff et al, 2004;Lin et al, 2013;Umedachi et al, 2016) (inspired by worms, caterpillars, and their gaits) (Jayaram and Full, 2016) (insects) (Chrispell et al, 2013;Cicconofri and DeSimone, 2015) (snakes) or build from scratch robots (Kim et al, 2014;Li et al, 2016) are under development; (2) the underwater locomotion (Fiazza et al, 2010), mainly inspired by fishes (Clark et al, 2015), turtles (Song et al, 2016), crabs (Calisti et al, 2016), chephalopods (Arienti et al, 2013;Cianchetti et al, 2015), rays (Urai et al, 2015), or other aquatic animals; and (3) manipulation, either at the level of grippers (Manti et al, 2015;Fakhari et al, 2016;Shintake et al, 2016), arms Elango and Faudzi, 2015;Katzschmann et al, 2015;Deashapriya et al, 2016;Sun et al, 2016), or other devices (Deng et al, 2016).…”

Hydrogels for Medical and Environmental Applications

“…Hydrogels are 3D monoliths which are water‐filled (amount of water can reach up to 90% of the hydrogel mass) and created by physicochemical actions, driving the starting materials into an assembly of cross‐linked networks . These strong cross‐linked networks prevent the entire system from solubilizing in spite of their high affinity for water .…”

Composite Polymeric Membranes with Directionally Embedded Fibers for Controlled Dual Actuation

“…Soft actuators made of materials able to change their shape or properties in response to environmental stimuli have attracted much interest in various applications such as sensors, optical and microfluidic devices, walkers and swimmers, and encapsulating/releasing systems . Actuation triggered by temperature, pH, light, electric, magnetic fields, and certain chemicals are well‐studied. Lately, multistimuli‐sensitive soft actuators have attracted more attention from applications' point of view.…”