Contact‐Free Remote Manipulation of Hydrogel Properties Using Light‐Triggerable Nanoparticles: A Materials Science Perspective for Biomedical Applications

Abstract

Considerable progress has been made in synthesizing "intelligent", biodegradable hydrogels that undergo rapid changes in physicochemical properties once exposed to external stimuli. These advantageous properties of stimulus-triggered materials make them highly appealing to diverse biomedical applications. Of late, research on the incorporation of light-triggered nanoparticles (NPs) into polymeric hydrogel networks has gained momentum due to their ability to remotely tune hydrogel properties using facile, contact-free approaches, such as adjustment of wavelength and intensity of light source. These multi-functional NPs, in combination with tissue-mimicking hydrogels, are increasingly being used for on-demand drug release, preparing diagnostic kits, and fabricating smart scaffolds. Here, the authors discuss the atomic behavior of different NPs in the presence of light, and critically review the mechanisms by which NPs convert light stimuli into heat energy. Then, they explain how these NPs impact the mechanical properties and rheological behavior of NPs-impregnated hydrogels. Understanding the rheological behavior of nanocomposite hydrogels using different sophisticated strategies, including computer-assisted machine learning, is critical for designing the next generation of drug delivery systems. Next, they highlight the salient strategies that have been used to apply light-induced nanocomposites for diverse biomedical applications and provide an outlook for the further improvement of these NPs-driven light-responsive hydrogels.

Tailoring the Inherent Properties of Biobased Nanoparticles for Nanomedicine

“…Furthermore, the properties of the biobased nanoparticles also vary from that of their bulk counterpart, requiring advanced tools and strategies for their thorough shape, size, and charge characterization. In addition, these nanoparticles can be supplemented with external stimuli-responsive nanomaterials for contact-free, on-demand targeted drug delivery, photothermal therapy, and bioimaging . Sancho-Albero et al recently designed mice cancer cell-derived exosomes encapsulating hollow gold nanoparticles for the thermal ablation of tumor cells .…”

“…Such polymeric scaffolds comprise of three-dimensional water-swellable hydrogels that can mimic the native extracellular matrices. − Advanced fabrication strategies of hydrogels, such as bioprinting, cryogelation, and electrospinning, can be used for preparing biobased-nanocomposite scaffolds for wound healing, bone regeneration, and cardiac therapy, among others. Additionally, such optimal nanocomposite hydrogel design strategies can be computed using machine learning-based approaches . Available data on hydrogels can be used to predict and model complex biophysical and biochemical interactions to reduce the cost and labor for preparing biobased nanocomposite scaffolds.…”

Responsive Hydrogels Based on Triggered Click Reactions for Liver Cancer

“…[32] Copyright 2021, The Royal Society of Chemistry. Internal stimuli pH-responsive PEG, TEG Inward diffusion [47,100,118,123,126,129] Redox-responsive PEG Inward diffusion [56,136,156] Enzyme-responsive ALG Cross-linking-codependent [14,27,106,124,130,132,158] Electroresponsive PLGA, PEG Inward diffusion [70,146,196] ROS-responsive PEG, PLGA Self-assembled [149,150,160,162,165] External stimuli Thermoresponsive PEG, PLGA In situ formation [7,30,34,42,67,170,171,173,175,17 8,181] Light-responsive PLGA, ALG Self-assembled [9,28,113,183,185] Magnetic-responsive ALG, HA Cross-linking-codependent [29,166,193,194,195] Mechanoresponsive PEG, PCL Inward diffusion [146,148,197,199,200] Ultrasound-responsive PEG Inward diffusion [14,163,201,…”

“…Hydrogels with a natural polymer base that are light-responsive can be altered in response to external light stimulations. [195,196] The environmental light stimulus acts as stimulation or triggering of drug release under different light conditions. [197,198] The absorption of photon energy by synthetic light-responsive materials is determined by the relevant energy bandgap of the electrons in the topmost occupied molecular orbital.…”

Smart Internal Bio‐Glues

“…[33][34][35] Recently, NIR lighttriggered hydrogels have been widely studied for photothermal therapy, tissue repair, drug release, and cell engineering, and the security concerns and thermal side effects have been demonstrated in several kinds of animal models. [35][36][37][38] Notably, upconversion nanoparticles (UCNPs)-assisted light-triggered reactions as a NIR light-responsive system, could easily convert NIR light into UV light as an internally secondary source to induce kinds of photochemical reactions, [39][40][41] which have been used for in vivo 3D printing [42] and controlled drug release. [41] Therefore, we speculated that one possible solution for the development of smart internal bio-glues for non-invasive or minimally invasive surgery should focus on the NIR light-responsive systems used in deep tissues by the incorporation of highly efficient UCNPs.…”