Controlled Shape Transformation and Loading Release of Smart Hemispherical Hybrid Microgels Triggered by ‘Inner Engines’

Abstract

The dynamic controlling and changing the shape of microgels, especially the anisotropic change, remains a challenge for the construction of advanced smart materials. To this end, the fabrication of hemispherical hybrid microgels (HHMs) with Au nanorods(AuNRs)‐based vesicles was demonstrated, with the thermo‐ and NIR light‐triggered anisotropic shape transformation and controlled release induced by ‘inner engines’. AuNRs‐based vesicles acting as ‘inner engines’ were first fabricated by the self‐assembly of thiol‐terminated block copolymers modified AuNRs, with the absorbance of NIR light (808 nm), thus generating heat in the system; second, poly(N‐isopropyl acrylamide) (pNIPAM)‐based HHMs containing AuNRs‐based vesicles were synthesized by the assistance of both microfluidics and photopolymerization. Importantly, uneven heat generated by the gradationally distributed AuNRs‐based vesicles in the hybrid microgels could cause an anisotropic shape change from hemispherical to mushroom‐like shape via external stimuli, with good reversibility and reproducibility. Based on this, the controlled release of loadings (e. g. Rhodamine B (RhB)) inside the engines of the microgels can be realized by combining NIR light irradiation and the shape transformation. Thus, HHMs with AuNRs‐vesicle‐based engines provide a novel platform for the investigation of drug release, artificial actuators, and micromotors.

Customized hybrid and NIR-light triggered thermoresponsive drug delivery microparticles synthetized by photopolymerization in a one-step flow focusing continuous microreactor

“…For this, we added the separately prepared HGNPs in the disperse phase of the coaxial flow microfluidic device to translate the synthesis conditions optimized in the previous section. Based on previous works where nanoparticles with photothermal properties 61,50 were encapsulated, the concentration of HGNPs was set at 10 mg/mL. Further, we confirmed their NIR responsive effect under laser irradiation (2.2 W/cm 2 ; λ= 808 nm).…”

“…In addition, this production strategy exerts the advantage that each MP is loaded with a similar cargo and that either the polymerization rate or the grade of crosslinking can be easily controlled. Considering previous limitations 50,51 that unable PNIPAm MPs polymerization in continuous flow, we selected dripping regime conditions instead of jetting conditions to promote a fast polymerization during the drop flow in the microfluidic system. The residence time of formed droplets is usually larger in dripping mode because low flow rates (inner and outer phases) are required.…”

“…Also, gold nanostructures have been widely used for light-triggered drug release from PNIPAm microcapsules 42 . Wang et al 50 recently showed the possibility to activate shape transition of Au nanorods-PNIPAm hybrid MPs using high power NIR laser irradiation. Those hybrid MPs were produced in several stages, resulting in a semicontinuous process: 1) Drop formation in continuous flow, 2) Drop sedimentation in stagnant conditions for 5 minutes after collection in order to fine tune the shape and 3) Drop photopolymerization in stagnant conditions under 365 nm UV light during 5 min.…”

“…But in this last case the double-emulsion droplets were incubated in a glass vial for 12 hours at room temperature to complete the polymerization, turning it also as a semi-continuous process, which represents a drawback to increase the productivity. Although a high control over the size and thermoresponsive properties of the MPs were achieved by the reported methods 50,51 , the production of PNIPAm hybrid MPs co-loading in the same MP drugs and metal nanoparticles (HGNPs) using a single flow device in continuous fashion by photopolymerization is still lacking. The development of a new flow synthesis approach that enables to address previous drawbacks would accelerate the translation of hybrid MPs applications for their future biomedical use.…”

Shape Shifting of Cup Shaped Particles on Growing poly (2‐hydroxy ethyl methacrylate) Brushes by “Grafting From” Approach and Dissipative Particle Dynamics Simulation

“…The shape change was thought to be controlled by kinetic manipulation of the phase behaviour of high molecular weight hydrophobic glassy segment. J. Wang and coworkers have also synthesized gold nanorods containing hemispherical hybrid microgels via self‐assembly of thiol‐terminated block copolymers which could anisotropically transform their shape from hemispheres to mushroom like shape under the stimuli of temperature and NIR‐laser. But these methods involve either multistep synthesis of desired polymer or high temperature for the fabrication of cup shaped particles.…”