Bifunctional Smart Hydrogel Dressing with Strain Sensitivity and NIR-Responsive Performance.

Smart response hydrogel has a broad application prospect in human health real-time monitoring due to its responses to a variety of stimuli. In this study, we developed a novel smart hydrogel dressing based on conductive MXene nanosheets and a temperature-sensitive PNIPAm polymer. γ-Methacryloxypropyltrimethoxysilane (KH570) was selected to functionalize the surface of MXene further to improve the interface compatibility between MXene and PNIPAm. Our prepared K-M/PNIPAm hydrogel was found to have a strain-sensitive property, as well as a respond to NIR phase change and volume change. When applied as a strain flexible sensor, this K-M/PNIPAm hydrogel exhibited a high strain sensitivity with a gauge factor (GF) of 4.491, a broad working strain range of ≈250%, a fast response of ∼160 ms, and good cycle stability (i.e., 3000 s at 20% strain). Besides, this K-M/PNIPAm hydrogel can be used as an efficient NIR light-controlled drug release carrier to achieve on-demand drug release. This work paved the way for the application of smart response hydrogel in human health real-time monitoring and NIR-controlled drug release functions.

Photomechanical Polymer Nanocomposites for Drug Delivery Devices.

We demonstrate a novel structure based on smart carbon nanocomposites intended for fabricating laser-triggered drug delivery devices (DDDs). The performance of the devices relies on nanocomposites' photothermal effects that are based on polydimethylsiloxane (PDMS) with carbon nanoparticles (CNPs). Upon evaluating the main features of the nanocomposites through physicochemical and photomechanical characterizations, we identified the main photomechanical features to be considered for selecting a nanocomposite for the DDDs. The capabilities of the PDMS/CNPs prototypes for drug delivery were tested using rhodamine-B (Rh-B) as a marker solution, allowing for visualizing and quantifying the release of the marker contained within the device. Our results showed that the DDDs readily expel the Rh-B from the reservoir upon laser irradiation and the amount of released Rh-B depends on the exposure time. Additionally, we identified two main Rh-B release mechanisms, the first one is based on the device elastic deformation and the second one is based on bubble generation and its expansion into the device. Both mechanisms were further elucidated through numerical simulations and compared with the experimental results. These promising results demonstrate that an inexpensive nanocomposite such as PDMS/CNPs can serve as a foundation for novel DDDs with spatial and temporal release control through laser irradiation.

γ-Radiation induced L-glutamic acid grafted highly porous, pH-responsive chitosan hydrogel beads: A smart and biocompatible vehicle for controlled anti-cancer drug delivery.

In the present work, highly porous, pH-responsive, and biocompatible chitosan-based hydrogel beads were prepared through gamma-irradiated graft copolymerization technique using L-glutamic acid as the monomer. The glutamic acid grafted chitosan (CH-g-GA) hydrogel beads, loaded with the anti-cancer drug (Doxorubicin, Dox), were exploited for their potential application as anti-cancer drug delivery system. The grafting conditions were optimized by varying irradiation dose (kGy) and monomer concentration. Further, the hydrogel beads were analysed using FTIR, XRD, SEM, TGA/DSC, Zeta potential studies, BET analysis and their strength was determined using rheological analysis. The swelling characteristics of the beads were studied at various simulated body pH (2.1, 5.8, and 7.4) to study their pH-responsive behaviour. The in-vitro drug release from the beads was thus evaluated at pH 5.8, 7.4 using UV-visible spectroscopy. The highest swelling ratio (426%) and drug release (81.33% in 144 h) was observed at the pH of 5.8. The MTT assay was performed on HEK-293 cell-line to check their cytocompatibilty and the cell proliferation of Dox-loaded beads was studied on MCF-7 cell-line. A significant cytotoxicity against the cancer-cells was observed which further established their promising use in the controlled delivery of anti-cancer agents for localized cancer therapy.

Combinational Hydrogel and Xerogel Actuators Showing NIR Manipulating Complex Actions.

Near-infrared (NIR)-driven shape memory hydrogels are synthesized with a one-pot polymerization of N,N-dimethylacrylamide in the inorganic clay and graphene oxide (GO) suspension. The hydrogel consists of only a physically crosslinked network, which is partially thermoreversible. With the efficient photothermal energy transformation of GO in the hydrogels, the shape recovery from the temporal shape is achieved by NIR irradiation. The optimal shape fixing percentage and recovery rate are found at moderate monomer and crosslinker contents. Meanwhile, the xerogel dried from the hydrogel also shows a fast NIR response shape change. The NIR manipulating combinational hydrogel-xerogel actuators are prepared by combining the wet and soft hydrogel and its dry and rigid xerogel together. The actuators achieve complex actions of turning and lifting under sequential NIR irradiation to carry an object up- and downward and around obstacles, or to transfer an object to a target position. This work provides a new idea for designing combinational actuators to fulfil complex actions.

Near-Infrared Light Activates Molecular Nanomachines to Drill into and Kill Cells.

Using two-photon excitation (2PE), molecular nanomachines (MNMs) are able to drill through cell membranes and kill the cells. This avoids the use of the more damaging ultraviolet light that has been used formerly to induce this nanomechanical cell-killing effect. Since 2PE is inherently confocal, enormous precision can be realized. The MNMs can be targeted to specific cell surfaces through peptide addends. Further, the efficacy was verified through a controlled opening of synthetic bilayer vesicles using the 2PE excitation of MNM that had been trapped within the vesicles.