Cu2-xSe/Bi2Se3@PEG Z-scheme heterostructure: a multimode bioimaging guided theranostic agent with enhanced photo/chemodynamic and photothermal therapy

Phototherapy in cancer treatment: strategies and challenges

Phototherapy has emerged as a promising modality in cancer treatment, garnering considerable attention for its minimal side effects, exceptional spatial selectivity, and optimal preservation of normal tissue function. This innovative approach primarily encompasses three distinct paradigms: Photodynamic Therapy (PDT), Photothermal Therapy (PTT), and Photoimmunotherapy (PIT). Each of these modalities exerts its antitumor effects through unique mechanisms-specifically, the generation of reactive oxygen species (ROS), heat, and immune responses, respectively. However, significant challenges impede the advancement and clinical application of phototherapy. These include inadequate ROS production rates, subpar photothermal conversion efficiency, difficulties in tumor targeting, and unfavorable physicochemical properties inherent to traditional phototherapeutic agents (PTs). Additionally, the hypoxic microenvironment typical of tumors complicates therapeutic efficacy due to limited agent penetration in deep-seated lesions. To address these limitations, ongoing research is fervently exploring innovative solutions. The unique advantages offered by nano-PTs and nanocarrier systems aim to enhance traditional approaches' effectiveness. Strategies such as generating oxygen in situ within tumors or inhibiting mitochondrial respiration while targeting the HIF-1α pathway may alleviate tumor hypoxia. Moreover, utilizing self-luminescent materials, near-infrared excitation sources, non-photoactivated sensitizers, and wireless light delivery systems can improve light penetration. Furthermore, integrating immunoadjuvants and modulating immunosuppressive cell populations while deploying immune checkpoint inhibitors holds promise for enhancing immunogenic cell death through PIT. This review seeks to elucidate the fundamental principles and biological implications of phototherapy while discussing dominant mechanisms and advanced strategies designed to overcome existing challenges-ultimately illuminating pathways for future research aimed at amplifying this intervention's therapeutic efficacy.

Heterojunction semiconductor nanocatalysts as cancer theranostics

Cancer nanotechnology is a promising area of cross-disciplinary research aiming to develop facile, effective, and noninvasive strategies to improve cancer diagnosis and treatment. Catalytic therapy based on exogenous stimulus-responsive semiconductor nanomaterials has shown its potential to address the challenges under the most global medical needs. Semiconductor nanocatalytic therapy is usually triggered by the catalytic action of hot electrons and holes during local redox reactions within the tumor, which represent the response of nontoxic semiconductor nanocatalysts to pertinent internal or external stimuli. However, careful architecture design of semiconductor nanocatalysts has been the major focus since the catalytic efficiency is often limited by facile hot electron/hole recombination. Addressing these challenges is vital for the progress of cancer catalytic therapy. In recent years, diverse strategies have been developed, with heterojunctions emerging as a prominent and extensively explored method. The efficiency of charge separation under exogenous stimulation can be heightened by manipulating the semiconducting performance of materials through heterojunction structures, thereby enhancing catalytic capabilities. This review summarizes the recent applications of exogenous stimulus-responsive semiconducting nanoheterojunctions for cancer theranostics. The first part of the review outlines the construction of different heterojunction types. The next section summarizes recent designs, properties, and catalytic mechanisms of various semiconductor heterojunctions in tumor therapy. The review concludes by discussing the challenges and providing insights into their prospects within this dynamic and continuously evolving field of research.

Precision Control of Amphoteric Doping in Cu x Bi2Se3 Nanoplates

Copper-doped Bi2Se3 (Cu x Bi2Se3) is of considerable interest for tailoring its electronic properties and inducing exotic charge correlations while retaining the unique Dirac surface states. However, the copper dopants in Cu x Bi2Se3 display complex electronic behaviors and may function as either electron donors or acceptors depending on their concentration and atomic sites within the Bi2Se3 crystal lattice. Thus, a precise understanding and control of the doping concentration and sites is of both fundamental and practical significance. Herein, we report a solution-based one-pot synthesis of Cu x Bi2Se3 nanoplates with systematically tunable Cu doping concentrations and doping sites. Our studies reveal a gradual evolution from intercalative sites to substitutional sites with increasing Cu concentrations. The Cu atoms at intercalative sites function as electron donors while those at the substitutional sites function as electron acceptors, producing distinct effects on the electronic properties of the resulting materials. We further show that Cu0.18Bi2Se3 exhibits superconducting behavior, which is not present in Bi2Se3, highlighting the essential role of Cu doping in tailoring exotic quantum properties. This study establishes an efficient methodology for precise synthesis of Cu x Bi2Se3 with tailored doping concentrations, doping sites, and electronic properties.

Fabrication of Interface Engineered S-Scheme Heterojunction Nanocatalyst for Ultrasound-Triggered Sustainable Cancer Therapy

In order to establish a set of perfect heterojunction designs and characterization schemes, step-scheme (S-scheme) BiOBr@Bi2S3 nanoheterojunctions that enable the charge separation and expand the scope of catalytic reactions, aiming to promote the development and improvement of heterojunction engineering is developed. In this kind of heterojunction system, the Fermi levels mediate the formation of the internal electric field at the interface and guide the recombination of the weak redox carriers, while the strong redox carriers are retained. Thus, these high-energy electrons and holes are able to catalyze a variety of substrates in the tumor microenvironment, such as the reduction of oxygen and carbon dioxide to superoxide radicals and carbon monoxide (CO), and the oxidation of H2O to hydroxyl radicals, thus achieving sonodynamic therapy and CO combined therapy. Mechanistically, the generated reactive oxygen species and CO damage DNA and inhibit cancer cell energy levels, respectively, to synergistically induce tumor cell apoptosis. This study provides new insights into the realization of high efficiency and low toxicity in catalytic therapy from a unique perspective of materials design. It is anticipated that this catalytic therapeutic method will garner significant interest in the sonocatalytic nanomedicine field.

Tumor Targeted Cuprous-Based Nanocomposite as Responsive Cascade Nanocatalyst for Efficient Tumor Synergistic Therapy

The single-functionality of traditional chemodynamic therapy (CDT) reagents usually limits the therapeutic efficacy of cancer treatment. Synergistic nanocomposites that involve cascade reaction provide a promising strategy to achieve satisfactory anticancer effects. Herein, a cuprous-based nanocomposite (CCS@GOx@HA) is fabricated, which owns the tumor targeting ability and can undergo tumor microenvironment responsive cascade reaction to enhance the tumor therapeutic efficiency significantly. Surface modification of nanocomposite with hyaluronic acid enables the targeted delivery of the nanocomposite to cancer cells. Acid-triggered decomposition of nanocomposite in cancer cell results in the release of Cu+ , Se2- and GOx. The Cu+ improves the Fenton-like reaction with endogenous H2 O2 to generate highly toxic • OH for CDT. While GOx can not only catalyze the in situ generation of endogenous H2 O2 , but also accelerate the consumption of intratumoral glucose to reduce nutrient supply in tumor site. In addition, Se2- further improves the therapeutic effects of CDT by upregulating the reactive oxygen species (ROS) in tumor cells. Meanwhile, the surface modification endows the nanocomposite the good water dispersibility and biocompatibility. Moreover, in vitro and in vivo experiments demonstrate satisfactory anti-cancer therapeutic performance by the synergistic cascade function of CCS@GOx@HA than CDT alone.

TRAIL-driven targeting and reversing cervical cancer radioresistance by seleno-nanotherapeutics through regulating cell metabolism

Recently, radioresistance has become a major obstacle in the radiotherapy of cervical cancer. To demonstrate enhanced radiosensitization against radioresistant cervical cancer, radioresistant cervical cancer cell line was developed and the mechanism of radioresistance was explored. Due to the overexpression of (death receptor 5, DR5) in cervical cancer, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-overexpressed cervical cancer cell membrane-camouflaged Cu2-xSe nanomedicine (CCMT) was designed. Since the CCMT was encapsulated with TRAIL-modified cell membrane, it represented high target to cervical cancer cell and immune evasion. Furthermore, Cu2-xSe had the ability to scavenge glutathione (GSH) and produce ·OH with excess H2O2 in the tumor microenvironment. The presence of CCMT combined with radiation therapy could effectively increase the 1O2 produced by X-rays. In vitro and in vivo studies elaborated that CCMT exhibited excellent radiosensitization properties to reverse radiotolerance by scavenging GSH and promoting DNA damage, apoptosis, mitochondrial membrane potential damage and metabolic disruption. Collectively, this study suggested that the development of TRAIL-overexpressed cell membrane-camouflaged Cu2-xSe nanomedicine could advance future cervical cancer treatment and minimize the disadvantages associated with radiation treatment.

Plasmonic Cu2-xSe Mediated Colorimetric/Photothermal Dual-Readout Detection of Glutathione

Plasmonic nanomaterials have attracted great attention in the field of catalysis and sensing for their outstanding electrical and optical properties. Here, a representative type of nonstoichiometric Cu_2-xSe nanoparticles with typical near-infrared (NIR) localized surface plasma resonance (LSPR) properties originating from their copper deficiency was applied to catalyze the oxidation of colorless TMB into their blue product in the presence of H₂O₂, indicating they had good peroxidase-like activity. However, glutathione (GSH) inhibited the catalytic oxidation of TMB, as it can consume the reactive oxygen species. Meanwhile, it can induce the reduction of Cu(II) in Cu_2-xSe, resulting in a decrease in the degree of copper deficiency, which can lead to a reduction in the LSPR. Therefore, the catalytic ability and photothermal responses of Cu_2-xSe were decreased. Thus, in our work, a colorimetric/photothermal dual-readout array was developed for the detection of GSH. The linear calibration for GSH concentration was in the range of 1-50 μM with the LOD as 0.13 μM and 50-800 μM with the LOD as 39.27 μM. To evaluate the practicability of the assay, tomatoes and cucumbers were selected as real samples, and good recoveries indicated that the developed assay had great potential in real applications.

Recent advances in stimuli-responsive nano-heterojunctions for tumor therapy

Stimuli-responsive catalytic therapy based on nano-catalysts has attracted much attention in the field of biomedicine for tumor therapy, due to its excellent and unique properties. However, the complex tumor microenvironment conditions and the rapid charge recombination in the catalyst limit catalytic therapy's effectiveness and further development. Effective heterojunction nanomaterials are constructed to address these problems to improve catalytic performance. Specifically, on the one hand, the band gap of the material is adjusted through the heterojunction structure to promote the charge separation efficiency under exogenous stimulation and further improve the catalytic capacity. On the other hand, the construction of a heterojunction structure can not only preserve the function of the original catalyst but also achieve significantly enhanced synergistic therapy ability. This review summarized the construction and functions of stimuli-responsive heterojunction nanomaterials under the excitation of X-rays, visible-near infrared light, and ultrasound in recent years, and further introduces their application in cancer therapy. Hopefully, the summary of stimuli-responsive heterojunction nanomaterials' applications will help researchers promote the development of nanomaterials in cancer therapy.

Metal selenide nanomaterials for biomedical applications

Metal selenide nanomaterials have received enormous attention as they possess diverse compositions, microstructures, and properties. The combination of selenium with various metallic elements gives the metal selenide nanomaterials distinctive optoelectronic and magnetic properties, such as strong near-infrared absorption, excellent imaging properties, good stability, and long in vivo circulation. This makes metal selenide nanomaterials advantageous and promising for biomedical applications. This paper summarizes the research progress in the last five years in the controlled synthesis of metal selenide nanomaterials in different dimensions and with different compositions and structures. Then we discuss how surface modification and functionalization strategies are well-suited for biomedical fields, including tumor therapy, biosensing, and antibacterial biological applications. The future trends and issues of metal selenide nanomaterials in the biomedical field are also discussed.

Image-Guided Precision Treatments

Chemotherapy, radiotherapy, and surgery are traditional cancer treatments, which usually produce unpredictable side effects and potential risks to normal healthy organs/tissues. Thus, safe and reliable treatment strategies are urgently required for maximized therapeutic efficiency to lesions and minimized risks to healthy regions. To this end, molecular imaging is responsible to undertake a specific targeting therapy. Besides that, the image guidance as a precision visualized approach for real-time in situ evaluations as well as an intraoperational navigation approach has earned attractive attention in the past decade. Along with the rapid development of multifunctional micro-/nanobiomaterials, versatile cutting-edge and advanced therapy strategies (e.g., thermal therapy, dynamic therapy, gas therapy, etc.) have been achieved and greatly contributed to the image-guided precision treatments in every aspect. Therefore, this chapter aims to discuss about both traditional and advanced cancer treatments and especially to elucidate the important roles that visualized medicine has been playing in the image-guided precision treatments.

Multifunctional Bi NSs@BSA Nanoplatform Guided by CT Imaging for Effective Photothermal Therapy

Photothermal therapy (PTT) has attracted great attention as an anticancer treatment strategy. With the rapid development of nanomedicine, multifunctional inorganic nanophotothermal agents provide a new way to improve the effect of PTT. Herein, bovine serum albumin (BSA)-modified Bi nanosheets (Bi NSs) with good biocompatibility were synthesized by a facile redox and ball milling method and applied as a photothermal agent for the enhancement of PTT. Owing to the strong near-infrared absorption, Bi NSs exhibit high photothermal conversion efficiency (η = 36.17%) under 808 nm laser irradiation and can serve as a nanotherapeutic agent for cancer therapy. In addition, in vitro cell safety analysis also suggests that the toxicity of BSA-modified Bi NSs is negligible. Upon 808 nm irradiation, the uptake ability of tumor cells to Bi NSs@BSA has been improved. Moreover, Bi NSs@BSA also can be used as a good contrast agent for CT imaging and then to observe the distribution of materials in the tumor site. Finally, Bi NSs@BSA-mediated PTT results show a high ablation rate of A549 tumor cells both in vitro and in vivo. All results reveal that Bi NSs@BSA is a promising nanotherapeutic platform for PTT.

Heterojunction Nanomedicine

Exogenous stimulation catalytic therapy has received enormous attention as it holds great promise to address global medical issues. However, the therapeutic effect of catalytic therapy is seriously restricted by the fast charge recombination and the limited utilization of exogenous stimulation by catalysts. In the past few decades, many strategies have been developed to overcome the above serious drawbacks, among which heterojunctions are the most widely used and promising strategy. This review attempts to summarize the recent progress in the rational design and fabrication of heterojunction nanomedicine, such as semiconductor-semiconductor heterojunctions (including type I, type II, type III, PN, and Z-scheme junctions) and semiconductor-metal heterojunctions (including Schottky, Ohmic, and localized surface plasmon resonance-mediated junctions). The catalytic mechanisms and properties of the above junction systems are also discussed in relation to biomedical applications, especially cancer treatment and sterilization. This review concludes with a summary of the challenges and some perspectives on future directions in this exciting and still evolving field of research.

Controlled Synthesis and Photoelectrochemical Performance Enhancement of Cu2−xSe Decorated Porous Au/Bi2Se3 Z-Scheme Plasmonic Photoelectrocatalyst

In this paper, uniform Cu2−xSe-modified Au/Bi2Se3 hybrid nanoparticles with porous shells have been prepared through a cation exchange method. Bi2Se3/Cu2−xSe Z-scheme heterojunction is introduced onto Au nanocube by replacing Bi3+ with Cu2+. Owing to the effective coupling between Au core and semiconductor shells, Au/Bi2Se3/Cu2−xSe hybrids present a broad and strong plasmon resonance absorption in the visible band. More intriguingly, the carrier lifetime of Au/Bi2Se3/Cu2−xSe hybrid photoelectrodes can be further tailored with corresponding Cu2−xSe content. Through parameter optimization, 0.1-Au/Bi2Se3/Cu2−xSe electrode exhibits the longest electron lifetime (86.03 ms) among all the parallel samples, and corresponding photoelectrochemical performance enhancement is also observed in the tests. Compared with that of pure Bi2Se3 (0.016% at 0.90 V vs. RHE) and Au/Bi2Se3 (0.02% at 0.90 V vs. RHE) nanoparticles, the maximum photoconversion efficiency of porous Au/Bi2Se3/Cu2−xSe hybrid photoanodes increased by 5.87 and 4.50 times under simulated sunlight illumination, attributing to the cooperation of Z-scheme heterojunction and plasmon resonance enhancement effects. All the results indicate that Au/Bi2Se3/Cu2−xSe porous hybrids combine eco-friendliness with excellent sunlight harvesting capability and effectively inhibiting the charge recombination, which provide a new idea for efficient solar-driven water splitting.

Chemodynamic Therapy via Fenton and Fenton-Like Nanomaterials: Strategies and Recent Advances

Chemodynamic therapy (CDT), a novel cancer therapeutic strategy defined as the treatment using Fenton or Fenton-like reaction to produce •OH in the tumor region, was first proposed by Bu, Shi, and co-workers in 2016. Recently, with the rapid development of Fenton and Fenton-like nanomaterials, CDT has attracted tremendous attention because of its unique advantages: 1) It is tumor-selective with low side effects; 2) the CDT process does not depend on external field stimulation; 3) it can modulate the hypoxic and immunosuppressive tumor microenvironment; 4) the treatment cost of CDT is low. In addition to the Fe-involved CDT strategies, the Fenton-like reaction-mediated CDT strategies have also been proposed, which are based on many other metal elements including copper, manganese, cobalt, titanium, vanadium, palladium, silver, molybdenum, ruthenium, tungsten, cerium, and zinc. Moreover, CDT has been combined with other therapies like chemotherapy, radiotherapy, phototherapy, sonodynamic therapy, and immunotherapy for achieving enhanced anticancer effects. Besides, there have also been studies that extend the application of CDT to the antibacterial field. This review introduces the latest advancements in the nanomaterials-involved CDT from 2018 to the present and proposes the current limitations as well as future research directions in the related field.

Component-optimized chemo-dynamic nanoagent for enhanced tumour cell-selective chemo-dynamic therapy with minimal side effect in glioma mouse model

Although CuO-deposited bovine serum albumin (CuO-BSA) and glucose oxidase (Gox) were combined to achieve H2O2 self-supplied chemo-dynamic therapy (CDT) and glucose consumption-based starvation therapy, the uses of copper and Gox...

Near-infrared photothermal performance of a metal-organic framework-based composite

The construction of heterostructures is a universal method to hinder the radiative recombination of hot electrons and hot holes, which can effectively enhance the photothermal effect of semiconductors. In this work, a one-pot method was employed to prepare a composite named Bi₂Se₃@ZIF-8 NPs, which incredibly increased the photothermal conversion efficiency of Bi₂Se₃ NPs. The temperature elevation of Bi₂Se₃@ZIF-8 NPs was almost double that of the Bi₂Se₃ NPs; specifically, the temperature of the irradiated Bi₂Se₃@ZIF-8 NPs was strikingly increased to 130 °C within 6 seconds, and finally stabilized at 165 °C. Furthermore, the photothermal conversion ability was maintained over multiple irradiation cycles, which endows this composite with great potential to be an excellent photothermal agent.