NIR laser-responsive liquid metal-loaded polymeric hydrogels for controlled release of doxorubicin

Integrin-Specific Stimuli-Responsive Nanomaterials for Cancer Theranostics

Background: Cancer is one of the leading causes of death worldwide. The tumor microenvironment makes the tumor difficult to treat, favoring drug resistance and the formation of metastases, resulting in death. Methods: Stimuli-responsive nanoparticles have shown great capacity to be used as a powerful strategy for cancer treatment, diagnostic, as well as theranostic. Nanocarriers are not only able to respond to internal stimuli such as oxidative stress, weakly acidic pH, high temperature, and the high expression of particular enzymes, but also to external stimuli such as light and paramagnetic characteristics to be exploited. Results: In this work, stimulus-responsive nanocarriers functionalized with arginine-glycine-aspartic acid (Arg-Gly-Asp) sequence as well as mimetic sequences with the capability to recognize integrin receptors are analyzed. Conclusions: This review highlights the progress that has been made in the development of new nanocarriers, capable of responding to endogenous and exogenous stimuli essential to combat cancer.

Liquid Metal as Energy Conversion Sensitizers: Materials and Applications

Energy can exist in nature in a wide range of forms. Energy conversion refers to the process in which energy is converted from one form to another, and this process will be greatly enhanced by energy conversion sensitizers. Recently, an emerging class of new materials, namely liquid metals (LMs), shows excellent prospects as highly versatile materials. Notably, in terms of energy delivery and conversion, LMs functional materials are chemical responsive, heat-responsive, photo-responsive, magnetic-responsive, microwave-responsive, and medical imaging responsive. All these intrinsic virtues enabled promising applications in energy conversion, which means LMs can act as energy sensitizers for enhancing energy conversion and transport. Herein, first the unique properties of the light, heat, magnetic and microwave converting capacity of gallium-based LMs materials are summarized. Then platforms and applications of LM-based energy conversion sensitizers are highlighted. Finally, some of the potential applications and opportunities of LMs are prospected as energy conversion sensitizers in the future, as well as unresolved challenges. Collectively, it is believed that this review provides a clear perspective for LMs mediated energy conversion, and this topic will help deepen knowledge of the physical chemistry properties of LMs functional materials.

Recent advances and progress on the design, fabrication and biomedical applications of Gallium liquid metals-based functional materials

Gallium (Ga) is a well-known liquid metals (LMs) that possesses the features, such as fluidity, low viscosity, high electrical and thermal conductivity, and relative low toxicity. Owing to the weak interactions between Ga atoms, Ga LMs can be adopted for fabrication of various Ga LMs-based functional materials via ultrasonic treatment and mechanical grinding. Moreover, many organic compounds/polymers can be coated on the surface of LMs-based materials through coordination between oxidized outlayers of Ga LMs and functional groups of organic components. Over the past decades, different strategies have been reported for synthesizing Ga LMs-based functional materials and their biomedical applications have been intensively investigated. Although some review articles have published over the past few years, a concise review is still needed to advance the latest developments in biomedical fields. The main context can be majorly divided into two parts. In the first section, various strategies for fabrication of Ga LMs-based functional materials via top-down strategies were introduced and discussed. Following that, biomedical applications of Ga LMs-based functional materials were summarized and design Ga LMs-based functional materials with enhanced performance for cancer photothermal therapy (PTT) and PTT combined therapy were highlighted. We trust this review article will be beneficial for scientists to comprehend this promising field and greatly advance future development for fabrication of other Ga LMs-based functional materials with better performance for biomedical applications.

Injectable composite hydrogels embedded with gallium-based liquid metal particles for solid breast cancer treatment via chemo-photothermal combination

Photothermal therapy (PTT) holds great promise as a cancer treatment modality by generating localized heat at the tumor site. Among various photothermal agents, gallium-based liquid metal (LM) has been widely used as a new photothermal-inducible metallic compound due to its structural transformability. To overcome limitations of random aggregation and dissipation of administrated LM particles into a human body, we developed LM-containing injectable composite hydrogel platforms capable of achieving spatiotemporal PTT and chemotherapy. Eutectic gallium-indium LM particles were first stabilized with 1,2-Distearoyl-sn‑glycero-3-phosphoethanolamine (DSPE) lipids. They were then incorporated into an interpenetrating hydrogel network composed of thiolated gelatin conjugated with 6-mercaptopurine (MP) chemodrug and poly(ethylene glycol)-diacrylate. The resulted composite hydrogel exhibited sufficient capability to induce MDA-MB-231 breast cancer cell death through a multi-step mechanism: (1) hyperthermic cancer cell death due to temperature elevation by near-infrared laser irradiation via LM particles, (2) leakage of glutathione (GSH) and cleavage of disulfide bonds due to destruction of cancer cells. As a consequence, additional chemotherapy was facilitated by GSH, leading to accelerated release of MP within the tumor microenvironment. The effectiveness of our composite hydrogel system was evaluated both in vitro and in vivo, demonstrating significant tumor suppression and killing. These results demonstrate the potential of this injectable composite hydrogel for spatiotemporal cancer treatment. In conclusion, integration of PTT and chemotherapy within our hydrogel platform offers enhanced therapeutic efficacy, suggesting promising prospects for future clinical applications. STATEMENT OF SIGNIFICANCE: Our research pioneers a breakthrough in cancer treatments by developing an injectable hydrogel platform incorporating liquid metal (LM) particle-mediated photothermal therapy and 6-mercaptopurine (MP)-based chemotherapy. The combination of gallium-based LM and MP achieves synergistic anticancer effects, and our injectable composite hydrogel acts as a localized reservoir for specific delivery of both therapeutic agents. This platform induces a multi-step anticancer mechanism, combining NIR-mediated hyperthermic tumor death and drug release triggered by released glutathione from damaged cancer populations. The synergistic efficacy validated in vitro and in vivo studies highlights significant tumor suppression. This injectable composite hydrogel with synergistic therapeutic efficacy holds immense promise for biomaterial-mediated spatiotemporal treatment of solid tumors, offering a potent targeted therapy for triple negative breast cancers.

Liquid metal-hydrogel composites for flexible electronics

As an emerging functional material, liquid metal-hydrogel composites exhibit excellent biosafety, high electrical conductivity, tunable mechanical properties and good adhesion, thus providing a unique platform for a wide range of flexible electronics applications such as wearable devices, medical devices, actuators, and energy conversion devices. Through different composite methods, liquid metals can be integrated into hydrogel matrices to form multifunctional composite material systems, which further expands the application range of hydrogels. In this paper, we provide a brief overview of the two materials: hydrogels and liquid metals, and discuss the synthesis method of liquid metal-hydrogel composites, focusing on the improvement of the performance of hydrogel materials by liquid metals. In addition, we summarize the research progress of liquid metal-hydrogel composites in the field of flexible electronics, pointing out the current challenges and future prospects of this material.

Current Progress in Gallium-based Liquid Metals for Combinatory Phototherapeutic Anticancer Applications

A variety of therapeutic approaches using liquid metal (LM) have been intensively investigated, due to its unique physico-chemical properties that include high surface tension, fluidity, shape deformability, thermal conductivity, and electrical conductivity. Among a series of LMs, the relatively lower toxicity and minimal volatility of gallium (Ga)-based LMs (GaLMs) enables their usage in a series of potential biomedical applications, especially implantable platforms, to treat multiple diseases. In addition, the highly efficient conversion of light energy into thermal or chemical energy via GaLMs has led to recent developments in photothermal and photodynamic applications for anticancer treatments. As attractive photothermal agents or photosensitizers, a systematic interpretation of the structural characteristics and photo-responsive behaviors of GaLMs is necessary to develop effective anticancer engineering applications. Therefore, the aim of this review is to provide a comprehensive summary of currently suggested GaLM-mediated photo-therapeutic cancer treatments. In particular, the review summarizes (1) surface coating techniques to form stable and multifunctional GaLM particulates, (2) currently investigated GaLM-mediated photothermal and photodynamic anticancer therapies, (3) synergistic efficacies with the aid of additional interventions, and (4) 3D composite gels embedded with GaLMs particles, to convey the potential technological advances of LM in this field.

Magnetic liquid metal loaded nano-in-micro spheres as fully flexible theranostic agents for SMART embolization

Transcatheter arterial chemoembolization (TACE) has become one of the preferred choices for advanced liver cancer patients. Current clinically used microsphere embolic agents, such as PVA, gelatin, and alginate microspheres, have limited therapeutic efficacy and lack the function of real-time imaging. In this work, we fabricated magnetic liquid metal nanoparticle (Fe@EGaIn NP) loaded calcium alginate (CA) microspheres (denoted as Fe@EGaIn/CA microspheres), which integrate CT/MR dual-modality imaging and photothermal/photodynamic functions of the Fe@EGaIn NP core, as well as embolization and drug-loading functions of CA microspheres. Namely, such nano-in-micro spheres can be used as fully flexible theranostic agents to achieve smart-chemoembolization. It has been confirmed by in vitro and in vivo experiments that Fe@EGaIn/CA microspheres have advantageous morphology, favorable biocompatibility, splendid versatility, and advanced embolic efficacy. Benefiting from these properties, excellent therapeutic efficiency was achieved with a tumor growth-inhibiting value of 100% in tumor-bearing rabbits. As a novel microsphere embolic agent with promising therapeutic efficacy and diagnostic capability, Fe@EGaIn/CA microspheres have shown potential applications in clinical transcatheter arterial chemoembolization. And the preparation strategy presented here provides a generalized paradigm for achieving multifunctional and fully flexible theranostics.

Mini/Micro/Nano Scale Liquid Metal Motors

Swimming motors navigating in complex fluidic environments have received tremendous attention over the last decade. In particular, liquid metal (LM) as a new emerging material has shown considerable potential in furthering the development of swimming motors, due to their unique features such as fluidity, softness, reconfigurability, stimuli responsiveness, and good biocompatibility. LM motors can not only achieve directional motion but also deformation due to their liquid nature, thus providing new and unique capabilities to the field of swimming motors. This review aims to provide an overview of the recent advances of LM motors and compare the difference in LM macro and micromotors from fabrication, propulsion, and application. Here, LM motors below 1 cm, named mini/micro/nano scale liquid metal motors (MLMTs) will be discussed. This work will present physicochemical characteristics of LMs and summarize the state-of-the-art progress in MLMTs. Finally, future outlooks including both opportunities and challenges of mini/micro/nano scale liquid metal motors are also provided.