Excellent Photothermal Properties Research Articles

Core–Shell Bacterial Cellulose/Graphene Oxide@Polydopamine Aerogel Fibers for Personal Thermal Management Textiles

AbstractThe porous nature and gel network of aerogel fibers make them ideal options for personal thermal management because they can significantly cut down on energy waste. However, aerogel fibers generally suffer from poor mechanical properties and single function. Herein, the porous continuous bacterial cellulose/graphene oxide@polydopamine core–shell aerogel fibers with high strength, excellent photothermal properties, and thermal insulation are investigated by wet spinning and freeze‐drying. The bacterial cellulose/graphene oxide@polydopamine aerogel fiber prepared by wet spinning method has a porous structure, which can prevent heat convection, reduce heat conduction, and suppress heat radiation, making the aerogel fiber have excellent thermal insulation properties. More crucially, graphene oxide may considerably enhance infrared radiation's capacity for heating, while polydopamine can enhance ultraviolet light absorption and boost photothermal conversion capability.

Multifunctional FFP2 Face Mask for White Light Disinfection and Pathogens Detection using Hybrid Nanostructures and Optical Metasurfaces.

A new generation of an FFP2 (Filtering Face Piece of type 2) smart face mask is achieved by integrating broadband hybrid nanomaterials and a self-assembled optical metasurface. The multifunctional FFP2 face mask shows simultaneously white light-assisted on-demand disinfection properties and versatile biosensing capabilities. These properties are achieved by a powerful combination of white light thermoplasmonic responsive hybrid nanomaterials, which provide excellent photo-thermal disinfection properties, and optical metasurface-based colorimetric biosensors, with a very low limit of pathogens detection. The realized system is studied in optical, morphological, spectroscopic, and cell viability assay experiments and environmental monitoring of harmful pathogens, thus highlighting the extraordinary properties in reusability and pathogens detection of the innovative face mask.

Facile Solvent-Free Fabrication of All-Small-Molecule Supramolecular Photothermal Bioadhesive for Sutureless Wound Closure.

Achieving underwater adhesion possesses a significant challenge, primarily due to the presence of interfacial water, which restricts the potential applications of adhesives. In this study, we present a straightforward and environmentally friendly one-pot approach for synthesizing a solvent-free supramolecular TPFe bioadhesive composed of thioctic acid, proanthocyanidins, and FeCl3. The bioadhesive exhibits excellent biocompatibility and photothermal antibacterial properties and demonstrates effective adhesion on various substrates in both wet and dry environments. Importantly, the adhesive strength of this bioadhesive on steel exceeds 1.2 MPa and that on porcine skin exceeds 100 kPa, which is greater than the adhesive strength of most reported bioadhesives. In addition, the bioadhesive exhibits the ability to effectively halt bleeding, close wounds promptly, and promote wound healing in the rat skin wound model. Therefore, the TPFe bioadhesive has potential as a medical bioadhesive for halting bleeding quickly and promoting wound healing in the biomedical field. This study provides a new idea for the development of bioadhesives with firm wet adhesion.

Cotton Fabric-Reinforced Hydrogels with Excellent Mechanical and Broad-Spectrum Photothermal Antibacterial Properties.

Antibacterial hydrogel wound dressings hold great potential in eliminating bacteria and accelerating the healing process. However, it remains a challenge to fabricate hydrogel wound dressings that simultaneously exhibit excellent mechanical and photothermal antibacterial properties. Here we report the development of polydopamine-functionalized graphene oxide (rGO@PDA)/calcium alginate (CA)/Polypyrrole (PPy) cotton fabric-reinforced hydrogels (abbreviated as rGO@PDA/CA/PPy FHs) for tackling bacterial infections. The mechanical properties of hydrogels were greatly enhanced by cotton fabric reinforcement and an interpenetrating structure, while excellent broad-spectrum photothermal antibacterial properties based on the photothermal effect were obtained by incorporating PPy and rGO@PDA. Results indicated that rGO@PDA/CA/PPy FHs exhibited superior tensile strength in both the warp (289 ± 62.1 N) and weft directions (142 ± 23.0 N), similarly to cotton fabric. By incorporating PPy and rGO@PDA, the swelling ratio was significantly decreased from 673.5% to 236.6%, while photothermal conversion performance was significantly enhanced with a temperature elevated to 45.0 °C. Due to the synergistic photothermal properties of rGO@PDA and PPy, rGO@PDA/CA/PPy FHs exhibited excellent bacteria-eliminating efficiency for S. aureus (0.57%) and E. coli (3.58%) after exposure to NIR for 20 min. We believe that the design of fabric-reinforced hydrogels could serve as a guideline for developing hydrogel wound dressings with improved mechanical properties and broad-spectrum photothermal antibacterial properties for infected-wound treatment.

Metal-polyphenol coordination nanosheets with synergistic peroxidase-like and photothermal properties for efficient antibacterial treatment

Bacterial infections pose a serious threat to human health and socioeconomics worldwide. In the post-antibiotic era, the development of novel antimicrobial agents remains a challenge. Polyphenols are natural compounds with a variety of biological activities such as intrinsic antimicrobial activity and antioxidant properties. Metal-polyphenol obtained by chelation of polyphenol ligands with metal ions not only possesses efficient antimicrobial activity but also excellent biocompatibility, which has great potential for application in biomedical and food packaging fields. Herein, we developed metal-polyphenol coordination nanosheets named copper oxidized tannic acid quinone (CuTAQ) possessing efficient antibacterial and anti-biofilm effects, which was synthesized by a facile one-pot method. The synthesis was achieved by chelation of partially oxidized tannic acid (TA) with Cu2+ under mild conditions, which supports low-cost and large-scale production. It was demonstrated that CuTAQ exhibited high antibacterial activity via disrupting the integrity of bacterial cell membranes, inducing oxidative stress, and interfering with metabolism. In addition, CuTAQ exhibits excellent peroxidase catalytic activity and photothermal conversion properties, which play a significant role in enhancing its bactericidal and biofilm scavenging abilities. This study provides insights for rational design of innovative metal-polyphenol nanomaterials with efficient antimicrobial properties.

A Bioactive Injectable Hydrogel Regulates Tumor Metastasis and Wound Healing for Melanoma via NIR-Light Triggered Hyperthermia.

Surgical resection remains the mainstream treatment for malignant melanoma. However, challenges in wound healing and residual tumor metastasis pose significant hurdles, resulting in high recurrence rates in patients. Herein, a bioactive injectable hydrogel (BG-Mngel) formed by crosslinking sodium alginate (SA) with manganese-doped bioactive glass (BG-Mn) is developed as a versatile platform for anti-tumor immunotherapy and postoperative wound healing for melanoma. The incorporation of Mn2+ within bioactive glass (BG) can activate the cGAS-STING immune pathway to elicit robust immune response for cancer immunotherapy. Furthermore, doping Mn2+ in BG endows system with excellent photothermal properties, hence facilitating STING activation and reversing the tumor immune-suppressive microenvironment. BG exhibits favorable angiogenic capacity and tissue regenerative potential, and Mn2+ promotes cell migration in vitro. When combining BG-Mngel with anti-PD-1 antibody (α-PD-1) for the treatment of malignant melanoma, it shows enhanced anti-tumor immune response and long-term immune memory response. Remarkably, BG-Mngel can upregulate the expression of genes related to blood vessel formation and promote skin tissue regeneration when treating full-thickness wounds. Overall, BG-MnGel serves as an effective adjuvant therapy to regulate tumor metastasis and wound healing for malignant melanoma.

Bletilla striata Polysaccharide-/Chitosan-Based Self-Healing Hydrogel with Enhanced Photothermal Effect for Rapid Healing of Diabetic Infected Wounds via the Regulation of Microenvironment.

The management of diabetic ulcers poses a significant challenge worldwide, and persistent hyperglycemia makes patients susceptible to bacterial infections. Unfortunately, the overuse of antibiotics may lead to drug resistance and prolonged infections, contributing to chronic inflammation and hindering the healing process. To address these issues, a photothermal therapy technique was incorporated in the preparation of wound dressings. This innovative solution involved the formulation of a self-healing and injectable hydrogel matrix based on the Schiff base structure formed between the oxidized Bletilla striata polysaccharide (BSP) and hydroxypropyltrimethylammonium chloride chitosan. Furthermore, the introduction of CuO nanoparticles encapsulated in polydopamine imparted excellent photothermal properties to the hydrogel, which promoted the release of berberine (BER) loaded on the nanoparticles and boosted the antibacterial performance. In addition to providing a reliable physical protection to the wound, the developed hydrogel, which integrated the herbal components of BSP and BER, effectively accelerated wound closure via microenvironment regulation, including alleviated inflammatory reaction, stimulated re-epithelialization, and reduced oxidative stress based on the promising results from cell and animal experiments. These impressive outcomes highlighted their clinical potential in safeguarding the wound against bacterial intrusion and managing diabetic ulcers.

Polydopamine-intercalated montmorillonite to mitigate polymerization inhibition for preparation of photothermal antibacterial and hemostatic hydrogel

The mechanical properties of hydrogels with in situ introduced polydopamine (PDA) will always be unsatisfactory owing to the polymerization inhibition of the catechol structure. Therefore, it is necessary to find a way to mitigate the inhibition. In this work, PDA-inserted montmorillonite (MMT) was first prepared. The micro-spacing of the MMT nanolayers limited the oxygen content which prevented the complete oxidation of the dopamine adsorbed between the MMT nanosheet layers and retained the catechol moiety. Then, polydopamine montmorillonite polyacrylamide (PMP) hydrogel was prepared under green LED irradiation. The hydrogel exhibited excellent mechanical properties and adhesive strength, as well as excellent photothermal properties and antimicrobial ability. After irradiation by NIR laser, the PMP hydrogel can be heated up and maintained at 50 ℃ within 2 min, and the antimicrobial rate reached 98 %. Meanwhile, PMP hydrogel presents excellent biocompatibility and hemostatic ability. Therefore, PMP hydrogel has a great potential in the field of photothermal therapy and hemostasis.

Stability, Thermophysical, Optical and Photothermal Properties of ZnO Nanofluids with Added Anionic/Cationic Mixed Surfactants

Metal oxide nanofluid is a new type of heat transfer medium with good thermal performance, which can be used to improve the heat collection and photothermal conversion performance of the collector. The development of new nanofluids with excellent stability, thermophysical and photothermal properties is very important for solar thermal utilization. In this paper, the ZnO nanofluids with SDS/CTAB mixed surfactants were prepared by two-step method. Their stability, thermophysical, optical and photothermal properties were studied based on experimental data. Then, the optimum concentration and preparation conditions of the proposed ZnO nanofluids adding SDS/CTAB with good photothermal performance were obtained. The results showed that the ZnO nanofluids with the addition of SDS/CTAB hybrid surfactant has good dispersion stability and its thermal conductivity can reach 0.772 W/(m·K). The transmittance was as low as 19.0.10% and the extinction coefficient was as high as 7.25 cm−1. In addition, the addition of the SDS/CTAB hybrid surfactant caused the ZnO nanofluids to exhibit better photothermal conversion efficiency up to 87%, which was superior to that of the control group with the addition of other surfactants. Therefore, ZnO nanofluids with the addition of SDS/CTAB have great potential as DASC working fluids.

Prussian blue nanoparticle-based pH-responsive self-assembly for enhanced photothermal and chemotherapy of tumors

In recent years, there has been growing interest in size-transformable nanoplatforms that exhibit active responses to acidic microenvironments, presenting promising prospects in the field of nanomedicine for tumor therapy. However, the design and fabrication of such size-adjustable nanotherapeutics pose significant challenges compared to size-fixed nanocomposites, primarily due to their distinct pH-responsive requirements. In this study, we developed pH-activated-aggregating nanosystems to integrate chemotherapy and photothermal therapy by creating size-transformable nanoparticles based on Prussian blue nanoparticles (PB NPs) anchored with acid-responsive polyoxometalates (POMs) quantum dots via electrostatic interactions (PPP NPs). Subsequently, we utilized doxorubicin (DOX) as a representative drug to formulate PPPD NPs. Notably, PPPD NPs exhibited a significant response to acidic conditions, resulting in changes in surface charge and rapid aggregation of PPP NPs. Furthermore, the aggregated PPP NPs demonstrated excellent photothermal properties under near-infrared laser irradiation. Importantly, PPPD NPs prolonged their retention time in tumor cells via a size-transformation approach. In vitro cellular assays revealed that the anticancer efficacy of PPPD NPs was significantly enhanced. The IC50 values for the PPPD NPs groupand the PPPD NPs + NIR group were 50.11 μg/mL and 30.9 μg/mL. Overall, this study introduces a novel strategy for cancer therapy, by developing size-aggregating nano-drugs with stimuli-responsive properties, holding promise for improved therapeutic outcomes in future combination approaches involving photothermal therapy and chemotherapy.

One-pot preparation of quercetin-doxorubicin dual-drug co-loaded nanosystem for multimodal treatment of tumors

The limitations of tumor treatment have long been attributed to drug resistance and the restricted therapeutic effects of chemotherapy. This study presents a simple and efficient one-pot synthesis approach to prepare a high drug-loading composite nanoparticle PVP/Fe-DOX@QCT (PFDQ). PFDQ exhibits excellent tumor targeting properties, with sustained drug release in the acidic environment of tumors. Furthermore, loading doxorubicin (DOX) and quercetin (QCT) in PFDQ not only reduces the toxicity of DOX to healthy cells but also inhibits the function of P-glycoprotein (P-gp), thus effectively blocking drug efflux. In addition, PFDQ shows excellent photothermal properties. When combined with photothermal therapy, PFDQ can effectively achieve light-to-heat conversion, thereby exerts synergistic effects. By integrating chemotherapy (DOX and QCT) with photothermal therapy, PFDQ established a powerful multimodal anti-tumor platform.

Programmable multi-stimulus-responsive whirligig beetle inspired soft robot with multifunctionality based on composite materials

In nature, surfaces are evolutionarily designed to allow species to adapt to their environments. Nowadays, more and more researchers have paid attention to soft robots based on superhydrophobic surfaces. Inspired by the swimming characteristics of whirligig beetles on the surface of water, we propose in this study a multi-stimulus-responsive soft robot that can be driven by light, magnetism and chemistry to achieve fast straight-line motions, turns and rotations on the surface of water. The soft robot is made of a composite material based on graphene oxide (GO) and polydimethylsiloxane (PDMS), which has high hydrophobicity and excellent photothermal properties. With a multi-stimulus-responsive driving mechanism, the soft robot can be used in applications such as oil recovery, cargo transportation, obstacle avoidance, and material dispersion. It is envisioned that this study can guide the development of multi-stimulus-responsive soft robots and offer some useful reference for their applications in water quality monitoring and oil recovery.

Mussel-inspired interface deposition strategy for mesoporous metal-phenolic nanospheres with superior antioxidative, photothermal and antibacterial performance

Metal-phenolic networks (MPNs) have emerged as a versatile and multifunctional platform applied in bioimaging, disease treatment, electrocatalysis, and water purification. The synthesis of MPNs with mesoporous frameworks and ultra-small diameters (<200 nm), crucial for post-modification, cargo loading, and mass transport, remains a formidable challenge. Inspired by mussel chemistry, mesoporous metal-phenolic nanospheres (MMPNs) are facilely prepared by direct deposition of the metal-polyphenol complex on the interface of oil nano-droplets composed of block copolymers/1,3,5-trimethylbenzene followed by a spontaneous template-removal process. Due to the penetrable and stable networks, the oil nano-droplets gradually leak from the networks driven by shear stress during the stirring process. As a result, MMPNs are obtained without additional template removal procedures such as solvent extraction or high-temperature calcination. The materials have a large pore size (∼12.1 nm), uniform spherical morphology with a small particle size (∼99 nm), and a large specific surface area (49.8 m2 g−1). Due to the abundant phenolic hydroxyl groups, the MMPNs show excellent antioxidative property. The MMPNs also have excellent photothermal property, whose photothermal conversion efficiency was 40.9 %. Moreover, the phenolic hydroxyl groups can reduce Ag+ in situ to prepare Ag nanoparticles loaded MMPNs composites, which have excellent inhibition performance of drug-resistant bacteria biofilm.

Deep eutectic supramolecular polymer functionalized MXene for enhancing mechanical properties, photothermal conversion, and bacterial inactivation of cellulose textiles

Two-dimensional (2D) transition metal carbides (Ti3C2Tx MXene) have gained significant attention for their potential in constructing diverse functional materials, However, MXene is easily oxidized and weakly bound to the cellulose matrix, which pose challenges in developing MXene-decorated non-woven fabric with strong bonding and stable thermal management properties. Herein, we successfully prepared deep eutectic supramolecular polymer (DESP) functionalized MXene to address these issues. MXene can be wrapped with DESP to be insulated from water and protected from being oxidized. Subsequently, we achieved an efficient in-situ deposition of DESP-functionalized MXene onto fibers through a combination of dip coating and photopolymerization technique. The resulting nonwoven fabric (CNs-DESP@M) exhibited excellent photothermal conversion properties along with rapid thermal response and functional stability. Interestingly, the interface bonding between MXene and the fiber surface was significantly enhanced due to the abundant pyrogallol groups in DESP, resulting in the composite textile exhibiting commendable mechanical properties (2.68 MPa). Moreover, the as-prepared textile demonstrates outstanding bactericidal efficacy against both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The multifunctional textile, created through a facile and efficient approach, demonstrates remarkable potential for applications in smart textiles, catering to the diverse needs of individuals in the future.

Composite Microparticles from Microfluidics for Chemo-/Photothermal Therapy of Hepatocellular Carcinoma.

Hydrogel microcarrier-based drug delivery systems are of great value in the combination therapy of tumors. Current research directions concentrate on the development of more economic, convenient, and effective combined therapeutic platforms. Herein, we developed novel adhesive composite microparticles (MPPMD) with combined chemo- and photothermal therapy ability via microfluidic electrospray technology for local hepatocellular carcinoma treatment. These composite microparticles consisted of doxorubicin (DOX)-loaded and polydopamine-wrapped mesoporous silicon and alginate. Benefiting from such a strategy of hierarchical structure drug loading, DOX could be gradually released from the system, effectively avoiding the direct toxicity of chemotherapeutics to the body. Additionally, the designed microparticles could not only effectively treat tumors by releasing the chemotherapy drug DOX but also show excellent photothermal properties under the irradiation of near-infrared light, achieving combined chemo- and photothermal treatment effects. Based on these advantages, the MPPMD could remarkably eliminate tumor cells in vitro and enormously restrict tumor development in vivo. These results illustrate that such composite microparticles are ideal combination treatment platforms, possessing promising expectations for cancer therapy.

Epigallocatechin-3-gallate derived polymer coated Prussian blue for synergistic ROS elimination and antibacterial therapy

Reactive oxygen species (ROS) play a vital role in wound healing process by fighting against invaded bacteria. However, excess ROS at the wound sites lead to oxidative stress that can trigger deleterious effects, causing cell death, tissue damage and chronic inflammation. Therefore, we fabricated a core–shell structured nanomedicine with antibacterial and antioxidant properties via a facile and green strategy. Specifically, Prussian blue (PB) nanozyme was fabricated and followed by coating a layer of epigallocatechin-3-gallate (EGCG)-derived polymer via polyphenolic condensation reaction and self-assembly process, resulting in PB@EGCG. The introduction of PB core endowed EGCG-based polyphenol nanoparticles with excellent NIR-triggered photothermal properties. Besides, owing to multiple enzyme-mimic activity of PB and potent antioxidant capacity of EGCG-derived polymer, PB@EGCG exhibited a remarkable ROS-scavenging ability, mitigated intracellular ROS level and protected cells from oxidative damage. Under NIR irradiation (808 nm, 1.5 W/cm2), PB@EGCG (50 µg/mL) exerted synergistic EGCG-derived polymer-photothermal antibacterial activity against Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus).In vivo therapeutic effect was evaluated using a S. aureus-infected rat model indicated PB@EGCG with a prominent bactericidal ability could modulate the inflammatory microenvironment and accelerate wound healing. Overall, this dual-functional nanomedicine provides a promising strategy for efficient antibacterial therapy.

Copper selenide nanosheets with photothermal therapy-related properties and multienzyme activity for highly effective eradication of drug resistance

Bacterial infections are among the most significant causes of death in humans. Chronic misuse or uncontrolled use of antibiotics promotes the emergence of multidrug-resistant superbugs that threaten public health through the food chain and cause environmental pollution. Based on the above considerations, copper selenide nanosheets (CuSe NSs) with photothermal therapy (PTT)- and photodynamic therapy (PDT)-related properties have been fabricated. These CuSe NSs possess enhanced PDT-related properties and can convert O2 into highly toxic reactive oxygen species (ROS), which can cause significant oxidative stress and damage to bacteria. In addition, CuSe NSs can efficiently consume glutathione (GSH) at bacterial infection sites, thus further enhancing their sterilization efficacy. In vitro antibacterial experiments with near-infrared (NIR) irradiation have shown that CuSe NSs have excellent photothermal bactericidal properties. These experiments also showed that CuSe NSs exerted excellent bactericidal effects on wounds infected with methicillin-resistant Staphylococcus aureus (MRSA) and significantly promoted the healing of infected wounds. Because of their superior biological safety, CuSe NSs are novel copper-based antimicrobial agents that are expected to enter clinical trials, serving as a modern approach to the major problem of treating bacterially infected wounds.

Metal-polyphenol based phase change microcapsules for photothermal conversion and storage

In this paper, a novel phase change microcapsules (MPN@PA) with metal-polyphenol (MPN) as shell material and paraffin (PA) as core material were prepared by interfacial self-assembly method. It has low preparation cost and shows excellent photothermal conversion and heat storage properties. The highest encapsulation rate of MPN@PA without leakage is 59.58% when the shell-core ration is 1.0:1.5. The morphology of MPN@PA is quasi-spheroid with the size of about 10∼26 μm. FT-IR and XRD analysis results show that MPN and PA are combined by hydrogen bonding, and no new substance is formed. The enthalpy of phase transformation of MPN@PA (1.0:1.5) is 140.9 J/g. Moreover, MPN@PA has excellent thermal stability, thermal reliability, photothermal conversion and heat storage efficiency (71.47%–73.31%). The prepared novel photothermal transformation microcapsule is expected to be applied to the high-efficiency storage, management and utilization of solar energy.

Solar-driven, highly-efficient, and environmentally-friendly oil spill cleanup by a superelastic photothermal thermoplastic polyurethane monolith with aligned channels

Cleanup of crude oil spills is challenging due to its high viscosity. Reducing the viscosity of crude oil by elevating its temperature and thus promoting absorption is considered a promising and environmentally-friendly way to address this worldwide issue. Herein, we propose a photothermal superelastic thermoplastic polyurethane (TPU)-based monolith with aligned channels successively modified with MXene and polydimethysiloxane (PDMS) (P-MXene@TPU) for crude oil absorption and recovery. The well-oriented structures help reduce mass transfer hindrance and accelerate heat transfer, while MXene and PDMS endow the monolith with excellent photothermal conversion property and hydrophobicity, respectively. P-MXene@TPU monolith demonstrates superior oil absorption performance under solar irradiation as self-heating is realized to decrease the crude oil viscosity and promote its absorption rate. Particularly noteworthy is that P-MXene@TPU monolith can bear 300 compression cycles with a deformation of 9 % owing to the superelastic TPU skeleton and aligned channels. The stable compression performance and anti-fatigue property validate that the monolith is suitable for recovering crude oil by extrusion. Continuous crude oil recovery is achieved via a pumping device and solar irradiation (1.0 kW/m2) enhances the recovery rate by a factor of 18, as compared to the one without irradiation. Given the unique structural design and exceptional properties, this monolith provides a highly efficient approach for handing the crude oil spills.

Photo-Sono activated fluorine-doped titanium-based bone implants for rapid osteosarcoma eradication and bacterial infection elimination

Inadequate elimination of tumor cells, bacterial infection, and insufficient bone fusion are the primary factors contributing to the recurrence of osteosarcoma and implant failure. To overcome these challenges, a multifunctional bioactive titanium-based implant consisting of fluorine-doped titanium dioxide (TiO2) nanoparticles was designed for synergistic therapy activated by near-infrared II (NIR-II) light and ultrasound. The F-doped TiO2 nanoparticles exhibit excellent photothermal and acoustic properties upon excitation by 1060 nm NIR-II laser and ultrasound, respectively. The synergistic effect of hyperthermia and reactive oxygen species (ROS) under photoacoustic action endows the TiO2 nanoparticles with remarkable anti-tumor and anti-bacterial activities, enabling them to eradicate Saos-2 cells within 10 min and S. aureus within 15 min. Meanwhile, the nanostructured surface and appropriate doping of F endow nanoparticles with excellent bone promoting ability.