Single-Material Solvent-Driven Polydimethylsiloxane Sponge Bending Actuators.

Soft robots mimic the agility of living organisms without rigid joints and muscles. Continuum bending (CB) is one type of motion living organisms can display. CB can be achieved using pneumatic, electroactive, or thermal actuators prepared by casting an active layer on a passive layer. The corresponding input actuates only the active layer in the assembly resulting in the bending of the structure. These two different layers must be laminated well during manufacturing. However, the formed bilayer can still delaminate later, and the detachment hampers the actuator's reversible, long-time use. An approach to creating a single material bending actuator was previously reported, for which spatial gradient swelling was used. This authentic approach allows a single material to be manufactured as a bending actuator, allowing easy access to such actuators without lamination. In this study, we show spatial porosity differences in the sponges of polydimethylsiloxane (PDMS) (a common material in soft robotics) can be used to create the required anisotropy for bending. The spongy polymers are manufactured through table sugar templates and actuated by (organic) solvent absorption/desorption. This enables some versatility in the mechanical properties, shape, actuation force, and actuation speed. The one-material system's straightforward production and seamless nature are advantageous for reversible and repetitive bending. This simple method can further be developed in hydrogels and polymers for soft robotics and functional materials.

GLUT-Targeting Phototherapeutic Nanoparticles for Synergistic Triple Combination Cancer Therapy.

The combination of multimodal therapies into one nanocarrier system is promising for its potential to enhance treatment performance by overcoming the efficacy problems encountered in conventional monomodal therapy. In this study, targeted and multimodal therapeutic hybrid nanocarriers are fabricated for breast cancer treatments. In this context, the synthesized gold nanorods (AuNRd), photothermal therapy (PTT) agent, are coated with doxorubicin (DOX) conjugated, targeted, and biocompatible tetrablock glycopeptide (P(DMAEMA-b-HMBAMA-b-FrucMA)-b-P(Lys)/DOX, P-DOX) polymer. Here, fructose-based (Fruc) glycopeptide polymer enhances cellular uptake into breast cancer through GLUT5. A photosensitizer molecule, indocyanine green (ICG), was loaded into the particles to provide photodynamic therapy (PDT) upon NIR light at 808 nm. In the final step of the fabrication, the polymer-coated nanoparticles are integrated with antisense ISIS5132 oligonucleotides to prevent apoptotic resistance of cells against drug molecules. The biocompatibility and therapeutic efficacy of the nanoparticles are evaluated on both human normal skin fibroblast cell (CCD-1079Sk) and human breast cancer cell (MCF7) lines. These multimodal therapeutic AuNRd@P-DOX/ICG/ISIS5132 nanoparticles demonstrate an efficient triple synergistic effect of chemo-/PTT/PDT, which is desired for breast cancer treatment. We believe that this promising multimodal therapeutic nanoparticle system can promote the further clinical application in the treatment of breast cancer and can also be adapted to other types of cancer.

Folic Acid-Conjugated pH and Redox-Sensitive Ellipsoidal Hybrid Magnetic Nanoparticles for Dual-Triggered Drug Release.

Stimuli-sensitive and multifunctional nanoparticles are highly desirable biomedical materials for triggered and targeted drug delivery applications. Here, we have designed pH- and redox-triggered magnetic lipid-polymer hybrid nanoparticles (MHNPs) with a core-shell structure. This design is composed of a silica-/mesoporous silica-coated ellipsoidal magnetic nanoparticle with multifunctionality: carrying the anticancer drug (doxorubicin, DOX), the cancer cell targeting ligand (folic acid-conjugated poly(ethylene glycol), FA-PEG) polymer, and being coated with a biocompatible pH-/redox-responsive (poly-l-histidine-poly(ethylene glycol)-lipoic acid; PLH-PEG-LA) polymer. The lipoic acid units of the PLH-PEG-LA shell of the FA-MHNPs were cross-linked using 1,4-dithiothreitol (DTT). When the FA-MHNPs-DOX were exposed to an endolysosomal pH of 5.5 and 10 mM glutathione (GSH), the particles exhibited a very efficient DOX release profile within 24 h. In addition, cytotoxicity, uptake, and apoptosis assays were performed against breast cancer cell lines. These results showed that FA-MHNPs-DOX promote an enhanced uptake and cell morbidity compared to the nontargeted MHNPs-DOX against tested cell lines. Moreover, the FA-MHNPs-DOX exhibited very effective cytotoxicity and also decreased the cell viability through apoptosis against breast cancer cell lines. In conclusion, it can be said that the pH and redox dual-responsive hybrid FA-MHNPs-DOX has a great potential for controlled drug release.

A novel pH/light-triggered surface for DNA adsorption and release.

A simple strategy for the immobilization of Cy3-labeled single strand DNA (Cy3-ssDNA) on a Si(001) surface and its release under control of both light and pH stimuli is presented. In order to prepare a dual pH/light-triggered surface, positively chargeable azobenzene molecules are self-assembled on the Si(001) surface. The surface wettability of this substrate can be changed under influence of both light and pH conditions. The substrates can be positively charged under mildly acidic conditions. The pH-sensitive behavior of the film allows binding of Cy3-ssDNA on the functionalized Si(001) surface through effective electrostatic interactions with the negatively charged polynucleotide backbone. Moreover, irradiation of the film with UVA light induces trans-cis isomerization of the azobenzene units on the surface. As a result, the binding affinity for DNA decreases due to the changing surface hydrophilicity. In order to understand and control the reversible photoswitchable mechanism of this surface, water contact angles are measured after UVA and visible light irradiation. The release of DNA from a dual pH/light-sensitive sample is performed using fluorescence microscopy. The results show that irradiation of the film with UVA light induces trans-cis isomerization of the photoresponsive azobenzene units; this leads to significant changes in the surface hydrophilicity and reduces the binding affinity for DNA.