<p>Intelligent Drug Delivery Microparticles with Visual Stimuli-Responsive Structural Color Changes</p>

Abstract

Background Particle-based drug delivery systems (DDSs) have a demonstrated value for drug discovery and development. However, some problems remain to be solved, such as limited stimuli, visual-monitoring. Aim To develop an intelligent multicolor DDSs with both near-infrared (NIR) controlled release and macroscopic color changes. Materials and Methods Microparticles comprising GO/pNIPAM/PEGDA composite hydrogel inverse opal scaffolds, with dextran and calcium alginate hydrogel were synthesized using SCCBs as the template. The morphology of microparticle was observed under scanning electron microscopy, and FITC-dextran-derived green fluorescence images were determined using a confocal laser scanning microscope. During the drug release, FITC-dextran-derived green fluorescence images were captured using fluorescent inverted microscope. The relationship between the power of NIR and the drug release rate was obtained using the change in optical density (OD) values. Finally, the amount of drug released could be estimated quantitatively used the structural color or the reflection peak position. Results A fixed concentration 8% (v/v) of PEGDA and 4mg/mL of GO was chosen as the optimal concentration based on the balance between appropriate volume shrinkage and structure color. The FITC-dextran was uniformly encapsulated in the particles by using 0.2 wt% sodium alginate. The microcarriers shrank because of the photothermal response and the intrinsic fluorescence intensity of FITC-dextran in the microparticles gradually decreased at the same time, indicating drug release. With an increasing duration of NIR irradiation, the microparticles gradually shrank, the reflection peak shifted toward blue and the structural color changed from red to orange, yellow, green, cyan, and blue successively. The drug release quantity can be predicted by the structural color of microparticles. Conclusion The multicolor microparticles have great potential in drug delivery systems because of its vivid reporting color, excellent photothermal effect, and the good stimuli responsivity.

Micromolding-Based Fabrication of Chemically Functional and Stimuli-Responsive Opal Microparticles via Evaporative Deposition–Neutralization

“…Briefly, the average fluorescence intensity linearly increased with CS content and then plateaued at 0.12 w/v% CS, illustrating the ready tunability of functionalization via simple and efficient amine-reactive chemistries rising from the highly nucleophilic amine moieties of CS. Finally, these results suggest that our microparticles can be further utilized to impart and deliver additional functionalities such as therapeutic small molecules (e.g., doxorubicin and fluorescein isothiocyanate (FITC)-dextran) via efficient conjugation chemistries by exploiting CS’s potent chemical functionality. , …”

“…Dissolution of lattice forming materials in opal structures allows the preparation of macroporous inverse opal (IO) materials that can be used in a wide range of applications, including the preparation of membranes, , 3D scaffolds for cell cultivation, , and capsules for controlled drug release. ,, Despite such substantial potential and recent attention, IO materials are usually prepared via complex multistep processing and suffer from compromised mechanical strength and/or nonuniform opalescence stemming from weak hollow structures formed upon dissolution of rigid nanospheres. , We thus examined the preparation of uniform IO microparticles via a simple PS dissolution process upon exposure to toluene, as shown in Figure . For this, CS-opal microparticles were lightly cross-linked using a homobifunctional cross-linker glutalaldehyde and then exposed to toluene for 48 h, as shown in the schematic diagram of Figure A.…”

“…Opal microparticles have garnered significant attention in a broad range of important applications due to their utility as chemical and biological sensors, 1,2 wound healing materials, 3 anticounterfeiting labels, 4 and drug delivery systems. 5,6 Substantial advances have been made in the fabrication techniques for opal microparticles, namely, microfluidics, 5,7,8 photolithography, 9 soft lithography, 10−12 and microscale printing techniques. 13 While being a widely used and mature technique, microfluidic production of opal microparticles suffers from several limitations, including the need for delicate control of microflows, harsh UV polymerization conditions that can limit the functionalization, and limited tunability of shapes and sizes.…”

Visible Light 3D Printing of High-Resolution Superelastic Microlattices of Poly(ethylene glycol) Diacrylate/Graphene Oxide Nanocomposites via Continuous Liquid Interface Production

“…The remarkable reinforcement by GO to PEGDA could be attributed to the noncovalent crosslinking effect of GO. As is well recognized, there are abundant oxygen-containing functional groups on the vast GO surface, which help strengthen the interfacial interaction between GO and PEGDA chains via hydrogen bonds and van der Waals forces. − Additionally, GO has a honeycomb-like carbon network with extremely high structural stability, which is capable of preventing the diffusion of cracks inside PEGDA and facilitating load transfer. As a result, the mechanical properties of GO/PEGDA composites could be greatly improved.…”

Multi-stimuli responsive photonic hydrogel based on a novel photonic crystal template containing gold nanorods

“…Photonic crystal (PC) with a periodic structure formed by the periodic arrangement of different refractive index media has attracted extensive attention on account of brilliant structural color through Bragg diffraction. [1][2][3] Therefore, a series of PC materials with vivid structural colors have been fabricated, which have significant application value in sensors, [4][5][6] drug delivery, [7][8][9] actuators, [10][11][12] printing [13][14][15] and other fields. [16][17][18] A hydrogel is a stimulus-responsive material due to its elastic network that can shrink and swell, so it is usually combined with PC to fabricate stimulus-responsive photonic hydrogels, which realize a visual conversion to optical signals by changing structural colors in response to external stimuli, such as light, 19,20 organic compounds and solvents, [21][22][23][24] metal ions, 25,26 temperature, [27][28][29] and pH.…”