Microneedle Patches with O2 Propellant for Deeply and Fast Delivering Photosensitizers: Towards Improved Photodynamic Therapy.

Photodynamic therapy (PDT) is an emerging technique for treating tumors. Especially, topical administration of photosensitizers (PSs) is more favorable for superficial tumor treatments with low systematic phototoxicity. Yet, ineffective migration of PSs to targeted tumor tissues and rapid consumption of O2 during PDT greatly limit their effects. Herein, PS-loaded microneedle (MN) patches with O2 propellant for a deeper and faster transdermal delivery of PS and improved PDT by embedding sodium percarbonate (SPC) into dissolving poly(vinyl pyrrolidone) MNs are presented. It is shown that SPC in the MNs can react with surrounding fluid to generate gaseous oxygen bubbles, forming vigorous fluid flows and thus greatly enhancing PS of chlorin e6 (Ce6) penetration in both hydrogel models and skin tissues. Reactive oxygen species (ROS) in hypoxic breast cancer cells (4T1 cells) are greatly increased by rapid penetration of PS and relief of hypoxia in vitro, and Ce6-loaded SPC MNs show an excellent cell-killing effect. Moreover, lower tumor growth rate and tumor mass after a 20-d treatment in tumor-bearing mice model verify the improved PDT in gaseous oxygen-droved delivery of PS. This study demonstrates a facile yet effective route of MN delivery of PSs for improved PDT in hypoxic tumor treatment.

Composite Polyelectrolyte Photothermal Hydrogel with Anti-biofouling and Antibacterial Properties for the Real-World Application of Solar Steam Generation.

Solar steam generation provides a promising and low-cost solution for freshwater production in energy scarcity areas. However, in real-world applications, evaporators are easily affected by microorganism contamination in source water, causing surface corrosion, structural damage, or even invalidation. Developing anti-biofouling and antibacterial evaporators is significant for long-term stable freshwater production. Herein, a composite polyelectrolyte photothermal hydrogel consisting of sulfobetaine methacrylate (SBMA), [2-(methacryloyloxy)ethyl]trimethylammonium chloride (METAC), and polypyrrole (PPy) with anti-biofouling and antibacterial properties is developed. Crediting sufficient ammonium groups and zwitterionic segments, the optimized polyelectrolyte hydrogel exhibits an ∼90% antibacterial ratio against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) and effectively controls biological contamination. Under 1.0 kW m-2 solar irradiation, a rapid water evaporation rate of ∼1.690 kg m-2 h-1 and a high solar-to-evaporation efficiency of ∼95.94% are achieved with the photothermal hydrogel. We show that a lab-made setup integrated with the hydrogel can realize ∼0.455 kg m-2 h-1 freshwater production from seawater under natural sunlight. Moreover, the hydrogel exhibits excellent durability with a stable evaporation rate of ∼1.617 kg m-2 h-1 in real seawater for over 6 weeks, making it fullhearted in the real-world application of solar steam generation.

Cationic Photothermal Hydrogels with Bacteria-Inhibiting Capability for Freshwater Production via Solar-Driven Steam Generation.

Solar-driven steam generation has been recognized as a sustainable and low-cost solution to freshwater scarcity using abundant solar energy. To harvest freshwater, various interfacial evaporators with rational designs of photothermal materials and structures have been developed concentrating on increasing the evaporation rate in the past few years. However, pathogenic microorganism accumulation on the evaporators by long-duration contact with natural water resources may lead to the deterioration of water transportation and the reduction of the evaporation rate. Here, we develop cationic photothermal hydrogels (CPHs) based on [2-(methacryloyloxy)ethyl]trimethylammonium chloride (METAC) and photothermal polypyrrole (PPy) with bacteria-inhibiting capability for freshwater production via solar-driven steam generation. A rapid water evaporation rate of 1.592 kg m-2 h-1 under simulated solar irradiation is achieved with CPHs floating on the water surface. Furthermore, we find that CPHs possess nearly 100% antibacterial performance against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The significant bacteria-inhibiting capability is mainly attributed to the large number of ammonium groups on the CPH network. Moreover, we show that CPHs exhibit good applicability with stable evaporation in natural lake water over 2 weeks, and the number of bacteria in purified lake water is significantly reduced. The device based on CPHs can achieve ∼0.49 kg m-2 h-1 freshwater production from lake water under natural sunlight. This study provides an attractive strategy for the evaporator to inhibit biological contamination and a potential way for long-term stable freshwater production from natural water resources in practical application.

Three-Dimensionally Structured Polypyrrole-Coated Setaria viridis Spike Composites for Efficient Solar Steam Generation.

Solar-driven steam generation is a promising technology for the production of freshwater from seawater and polluted water. High water evaporation rates have been achieved via the interfacial heating scheme; however, they are still limited to meet the increasing need for freshwater due to the restricted evaporation area of two-dimensionally (2D) geometrical planar photothermal membranes. Herein, a three-dimensionally (3D) structured solar evaporator is prepared via coating photothermal polypyrrole (PPy) on the spike of Setaria viridis(S. viridis) for highly efficient evaporation. Due to the enlarged evaporation area and open structure for vapor dissipation, the PPy-coated S. viridis spike solar evaporator shows a high water evaporation rate of 3.72 kg m-2 h-1 under one sun illumination. The 3D solar evaporator also demonstrates good durability and anti-salt-clogging performance for real-life applications. Furthermore, we show that the 3D solar evaporator demonstrates effective decontamination of saline water, dye-contaminated water, and corrosive water. This work can inspire new paradigms toward developing high-performance solar steaming technologies for effective water purification to address the worldwide crisis of freshwater shortage.

Moist-Induced Electricity Generation by Electrospun Cellulose Acetate Membranes with Optimized Porous Structures.

Harvesting energy from moist in the atmosphere has recently been demonstrated as an effective manner for a portable power supply to meet the ever-increasing demands of energy consumption. Porous materials are shown to have great potential in moist-induced electricity generation. Herein, we report moist-induced electricity generation by electrospun cellulose acetate (CA) membranes with optimized porous structures. We show that the pore size and porosity of CA membranes can be readily tuned via a facile compression and annealing process, and the effect of pore features on the output voltages can thus be investigated systematically. We find that, at a relatively high porosity, the electricity-generation performance can be further enhanced by constructing a smaller pore to form more nanochannels. Porous CA membranes, with an optimized porosity of 52.6% and a pore diameter less than 250 nm, are prepared to construct moist-induced electricity generators, which can be applied as breath sensors and can power up calculator operation. The current study provides insights for the construction of porous materials with different pore characteristics for moist-induced electricity generation, especially in the exploration of more efficient and low-cost porous materials for large-scale practical application of the portable power supply.

Multifunctional Ag3PO4-rGO-Coated Textiles for Clean Water Production by Solar-Driven Evaporation, Photocatalysis, and Disinfection.

Solar-driven water evaporation is of great importance for freshwater production via solar distillation and has attracted growing attention recently by the development of heat localization strategies. Yet, when polluted water is used as the source water, solar-driven water evaporation might further deteriorate the pollution. In this study, we report the facile preparation of multifunctional Ag3PO4-reduced graphene oxide (Ag3PO4-rGO) nanocomposite-coated textiles for clean water production by solar-driven water evaporation, photocatalysis, and disinfection. The multifunctional textiles are obtained through coating Ag3PO4-rGO nanocomposites onto cotton textile substrates. The resulting textile can float on the water surface, absorb solar light, and convert it into heat, enhancing the water surface temperature and promoting water evaporation. We show that with Ag3PO4-rGO nanocomposite-coated textiles on the water surface, a high water evaporation rate of 1.31 kg/(m2 h) can be reached under solar light irradiation. Furthermore, the textiles can simultaneously decompose organic dyes and disinfect pathogenic microbes in water, purifying the raw water during solar-driven water evaporation. Such an all-in-one multifunctional textile provides a facile yet sustainable strategy for freshwater production.

Metallosupramolecular Photonic Elastomers with Self-Healing Capability and Angle-Independent Color.

Photonic elastomers that can change colors like a chameleon have shown great promise in various applications. However, it still remains a challenge to produce artificial photonic elastomers with desired optical and mechanical properties. Here, the generation of metallosupramolecular polymer-based photonic elastomers with tunable mechanical strength, angle-independent structural color, and self-healing capability is reported. The photonic elastomers are prepared by incorporating isotropically arranged monodispersed SiO2 nanoparticles within a supramolecular elastomeric matrix based on metal coordination interaction between amino-terminated poly(dimethylsiloxane) and cerium trichloride. The photonic elastomers exhibit angle-independent structural colors, while Young's modulus and elongation at break of the as-formed photonic elastomers reach 0.24 MPa and 150%, respectively. The superior elasticity of photonic elastomers enables their chameleon-skin-like mechanochromic capability. Moreover, the photonic elastomers are capable of healing scratches or cuts to ensure sustainable optical and mechanical properties, which is crucial to their applications in wearable devices, optical coating, and visualized force sensing.