A Facile One-Pot Synthesis of a Two-Dimensional MoS2 /Bi2S3 Composite Theranostic Nanosystem for Multi-Modality Tumor Imaging and Therapy

Highly Efficient 2D NIR-II Photothermal Agent with Fenton Catalytic Activity for Cancer Synergistic Photothermal-Chemodynamic Therapy

Photothermal therapy (PTT) has emerged as a promising cancer therapeutic modality with high therapeutic specificity, however, its therapeutic effectiveness is limited by available high-efficiency photothermal agents (PTAs), especially in the second near-infrared (NIR-II) biowindow. Here, based on facile liquid-exfoliated FePS3 nanosheets, a highly efficient NIR-II PTA with its photothermal conversion efficiency of up to 43.3% is demonstrated, which is among the highest reported levels in typical PTAs. More importantly, such Fe-based 2D nanosheets also show superior Fenton catalytic activity facilitated by their ultrahigh specific surface area, simultaneously enabling cancer chemodynamic therapy (CDT). Impressively, the efficiency of CDT could be further remarkably enhanced by its photothermal effect, leading to cancer synergistic PTT/CDT. Both in vitro and in vivo studies reveal a highly efficient tumor ablation under NIR-II light irradiation. This work provides a paradigm for cancer CDT and PTT in the NIR-II biowindow via a single 2D nanoplatform with desired therapeutic effect. Furthermore, with additional possibilities for magnetic resonance imaging, photoacoustic tomography, as well as drug loading, this Fe-based 2D material could potentially serve as a 2D "all-in-one" theranostic nanoplatform.

Bismuth-Based Nanomaterials: Recent Advances in Tumor Targeting and Synergistic Cancer Therapy Techniques

Despite all of the efforts in the field of cancer therapy, the heterogeneous properties of tumor cells induce an insufficient therapeutic outcome when treated with conventional monotherapies, necessitating a shift in cancer treatment from monotherapy to combination therapy for complete cancer treatment. Multifunctional bismuth (Bi)-based nanomaterials (NMs) with therapeutic functions hold great promise for the fields of cancer diagnosis and therapy based on their low toxicity, X-ray sensitive capabilities, high atomic number, near-infrared driven semiconductor properties, and low cost. Herein, a comprehensive review of recent advances in various medicinal aspects of Bi-based NMs is presented including: evaluation of in-tumor site accumulation, tumor targeting, and therapeutic performance, as well as the characteristics, benefits, and shortcomings of Bi-based NM-mediated major monotherapies. In addition, the cooperative enhancement mechanisms between two or more of these monotherapies are described in detail to address common challenges in cancer therapy, such as multidrug resistance, hypoxia, and metastasis. Finally, this review opens new insights into the design of multimodal synergistic therapies for potential future clinical applications of Bi-based NMs.

Conjugation of a Scintillator Complex and Gold Nanorods for Dual-Modal Image-Guided Photothermal and X-ray-Induced Photodynamic Therapy of Tumors

Light-mediated therapy has many unique merits but monotherapy strategies rarely completely inhibit tumor growth because resistance often develops. Combination therapy is a promising strategy in oncology and has demonstrated superior safety and efficacy over monotherapy. Here, we conjugated a scintillator complex and gold nanorod nanosensitizer for dual-modal image-guided photothermal and X-ray-induced photodynamic therapy (PDT). Lanthanide complexes were successfully conjugated and offer excellent X-ray-excited optical luminescence for PDT effects. The strong near-infrared (NIR) light and X-ray absorption abilities of gold nanorods make the nanosensitizer function as both a photothermal agent for photothermal therapy and a radiosensitizer for enhanced radiotherapy. The studies in vitro and in vivo demonstrated that the nanosensitizer offers good dual-modal imaging capability and significantly suppresses tumor progression under NIR light and X-ray irradiation. This work shows the great potential of conjugating scintillator lanthanide complexes and gold nanosensitizers for multimodal image-guided therapy of deep-seated tumors.

Copper chalcogenide materials as photothermal agents for cancer treatment

Copper-based chalcogenide nanomaterials have made tremendous progress for cancer theranostics due to their simple preparation, low cost, stable performance, and easy functionalization. But a systematic review and analysis about them does not exist. Therefore, we offer an account, mainly focusing on the design and functionalization of the copper-based chalcogenide nanomaterials for cancer theranostics, aiming to briefly demonstrate the design and concepts, summarize some of the past studies and analyze the development trends in the copper-based chalcogenide nanomaterials for clinical application.

Synthesis of gold-silica core-shell nanoparticles by pulsed laser ablation in liquid and their physico-chemical properties towards photothermal cancer therapy

Due to the increasing scientific and biomedical interest in various nanoparticles (NPs) with excellent properties and the onset of their commercial use, a convenient and adjustable physical method for improved efficiency needs to be used for enabling their tech-scale production. Recently, great progress has been made in the large-scale production of NPs with a simple structure by pulsed laser ablation in liquid (PLAL). In this work, we synthesized gold-silica core-shell NPs by improved PLAL and provided a guide on how to investigate their physico-chemical properties and association with biological effects towards cancer photothermal therapy (PTT). By means of this method, reproducible and scalable liquid phase NPs with less toxicity and good stability can be realized for tech-scale production based on its further adjustment and modification. Moreover, a more complete investigation of the associations between the physico-chemical properties of functional NPs with complex structure and their biological effects may enable more targeted NPs towards specific requirements of biomedical applications.

The versatile biomedical applications of bismuth-based nanoparticles and composites: therapeutic, diagnostic, biosensing, and regenerative properties

Studies of nanosized forms of bismuth (Bi)-containing materials have recently expanded from optical, chemical, electronic, and engineering fields towards biomedicine, as a result of their safety, cost-effective fabrication processes, large surface area, high stability, and high versatility in terms of shape, size, and porosity. Bi, as a nontoxic and inexpensive diamagnetic heavy metal, has been used for the fabrication of various nanoparticles (NPs) with unique structural, physicochemical, and compositional features to combine various properties, such as a favourably high X-ray attenuation coefficient and near-infrared (NIR) absorbance, excellent light-to-heat conversion efficiency, and a long circulation half-life. These features have rendered bismuth-containing nanoparticles (BiNPs) with desirable performance for combined cancer therapy, photothermal and radiation therapy (RT), multimodal imaging, theranostics, drug delivery, biosensing, and tissue engineering. Bismuth oxyhalides (BiO_x, where X is Cl, Br or I) and bismuth chalcogenides, including bismuth oxide, bismuth sulfide, bismuth selenide, and bismuth telluride, have been heavily investigated for therapeutic purposes. The pharmacokinetics of these BiNPs can be easily improved via the facile modification of their surfaces with biocompatible polymers and proteins, resulting in enhanced colloidal stability, extended blood circulation, and reduced toxicity. Desirable antibacterial effects, bone regeneration potential, and tumor growth suppression under NIR laser radiation are the main biomedical research areas involving BiNPs that have opened up a new paradigm for their future clinical translation. This review emphasizes the synthesis and state-of-the-art progress related to the biomedical applications of BiNPs with different structures, sizes, and compositions. Furthermore, a comprehensive discussion focusing on challenges and future opportunities is presented.

Advances in nanomaterials for photodynamic therapy applications: Status and challenges

Photodynamic therapy (PDT), as a non-invasive therapeutic modality that is alternative to radiotherapy and chemotherapy, is extensively investigated for cancer treatments. Although conventional organic photosensitizers (PSs) are still widely used and have achieved great progresses in PDT, the disadvantages such as hydrophobicity, poor stability within PDT environment and low cell/tissue specificity largely limit their clinical applications. Consequently, nano-agents with promising physicochemical and optical properties have emerged as an attractive alternative to overcome these drawbacks of traditional PSs. Herein, the up-to-date advances in the fabrication and fascinating applications of various nanomaterials in PDT have been summarized, including various types of nanoparticles, carbon-based nanomaterials, and two-dimensional nanomaterials, etc. In addition, the current challenges for the clinical use of PDT, and the corresponding strategies to address these issues, as well as future perspectives on further improvement of PDT have also been discussed.

Phototherapy with layered materials derived quantum dots

Quantum dots (QDs) originating from two-dimensional (2D) sheets of graphitic carbon nitride (g-C₃N₄), graphene, hexagonal boron nitride (h-BN), monoatomic buckled crystals (phosphorene), germanene, silicene and transition metal dichalcogenides (TMDCs) are emerging zero-dimensional materials. These QDs possess diverse optical properties, are chemically stable, have surprisingly excellent biocompatibility and are relatively amenable to surface modifications. It is therefore not difficult to see that these QDs have potential in a variety of bioapplications, including biosensing, bioimaging and anticancer and antimicrobial therapy. In this review, we briefly summarize the recent progress of these exciting QD based nanoagents and strategies for phototherapy. In addition, we will discuss about the current limitations, challenges and future prospects of QDs in biomedical applications.

Facile one-pot synthesis of novel hierarchical Bi2O3/Bi2S3 nanoflower photocatalyst with intrinsic p-n junction for efficient photocatalytic removals of RhB and Cr(VI)

The construction of heterojunction system can promote the separation and transfer of photogenerated electron-hole pairs, which is conducive to the degradation of sewage. In this paper, heterostructured Bi₂O₃/Bi₂S₃ nanoflowers are fabricated by a one-step hydrothermal method. The microstructure and optical absorption properties are studied through the detailed characterization of this heterojunction. The visible light photocatalytic ability of as-prepared Bi₂O₃/Bi₂S₃ heterojunctions are investigated by photocatalytic removals of RhB and Cr(VI). The results of photocatalysis indicate that removal efficiencies of RhB and Cr(VI) over Bi₂O₃/Bi₂S₃ heterojunction are higher than those of pure Bi₂O₃ and Bi₂S₃. The improved photocatalytic performance of the Bi₂O₃/Bi₂S₃ heterojunctions could be attributed to a combination of the p-n junction between the p-type Bi₂S₃ and n-type Bi₂O₃, and large specific surface areas (46.31 m² g^-1). Moreover, the probable photocatalytic mechanism of composite photocatalysts is explored in detail by active species trapping experiments, N₂ adsorption-desorption, the transient photovoltage electrochemical impedance spectroscopy and photoluminescence measurements. This work provides new insights into building of the efficient and novel heterogeneous photocatalysts and other energy-related devices.

Fast and selective detection of mercury ions in environmental water by paper-based fluorescent sensor using boronic acid functionalized MoS2 quantum dots

In this study, the B-MoS₂ QDs, boronic acid functionalized MoS₂ quantum dots, are synthesized by a simple aminoacylation reaction between MoS₂ QDs and 3-aminobenzeneboronic acid (APBA). It not only exhibits excellent thermo-stability, photo-stability and good salt tolerance, but shows excellent fluorescence stability even under industrial wastewater with high concentration. These good characters can be used to construct a new fluorescence sensor for sensitive and selective detection of mercury ions (Hg²⁺). The fluorescence intensity of B-MoS₂ QDs linearly decreases with the increase of Hg²⁺ concentration ranging from 0.005 to 41 μmol L^-1, and the limit of detection as low as 1.8 nmol L^-1. Due to the mercury ion-promoted transmetalation reaction of aryl boronic acid, this proposed method exhibits fast response, ultra-sensitivity and high selectivity for analysis of Hg²⁺ in different environmental water, and which also uses to online monitoring of Hg²⁺. The B-MoS₂ QDs-based test paper can be used to detect the trace amounts of Hg²⁺ under UV lamp by naked eyes, suggesting that the proposed method has potential application in on-site monitoring of environmental Hg²⁺.

Recent advances in transition metal based compound catalysts for water splitting from the perspective of crystal engineering

A review of the recent progress on the transition metal based catalysts for water splitting with emphasis on crystal engineering.

Nanomedicine-Enabled Modulation of Tumor Hypoxic Microenvironment for Enhanced Cancer Therapy

Hypoxia is a common condition of solid tumors that is mainly caused by enhanced tumor proliferative activity and dysfunctional vasculature. In the treatment of hypoxic human solid tumors, many conventional therapeutic approaches (e.g., oxygen-dependent photodynamic therapy, anticancer drug-based chemotherapy or X-ray induced radiotherapy) become considerably less effective or ineffective. In recent years, various strategies have been explored to deliver or generate oxygen inside solid tumors to overcome tumorous hypoxia and show promising evidence to improve the antitumor efficiency. In this review, the extrinsic regulation of tumor hypoxia via nanomaterial delivery is discussed followed by a summary of the mechanisms through which the modulated tumor hypoxic microenvironment improves therapeutic efficacy. The review concludes with future perspectives, to specifically address the translation of nanomaterial-based therapeutic strategies for clinical applications.

"All-in-One" Theranostic Agent with Seven Functions Based on Bi-Doped Metal Chalcogenide Nanoflowers

Most of the existing single-component nanostructures cannot provide comprehensive diagnostic information, and their treatment strategies always have to combine other therapeutics as a complementary for effective biomedical application. Here, we adopted a facile approach to design a theranostic nanoflower (NF) with robust efficacy for comprehensive tumor diagnosis and quadruple synergistic cancer therapy. The NF is equipped with a metallic hybrid of several functional elements and flower-like superstructures and thus shows excellent in vitro and in vivo theranostic performance. It shows high X-ray attenuation coefficiency for the Bi element, strong near-infrared (NIR) plasmon absorbance and singlet oxygen (¹O₂) generation ability for the Mo element, and great photothermal conversion efficiency (54.7%) because of enhanced photoabsorption of the petal structure. Moreover, the NF realizes a very high doxorubicin-loading efficiency (90.0%) and bimodal pH/NIR-responsive drug release, posing a promise as a controlled drug carrier. The NF also shows excellent performance at trimodal magnetic resonance/X-ray computed tomography/photoacoustic imaging for comprehensive tumor diagnosis. To our best knowledge, it is the first time that integrating at least seven functions into one biomedical nanomaterial for well-rounded tumor theranostics has been reported. This "all-in-one" NF opens a new perspective in developing novel and efficient multifunctional nanotheranostics.

Two-dimensional nanomaterials: fascinating materials in biomedical field

Due to their high anisotropy and chemical functions, two-dimensional (2D) nanomaterials have attracted increasing interest and attention from various scientific fields, including functional electronics, catalysis, supercapacitors, batteries and energy materials. In the biomedical field, 2D nanomaterials have made significant contributions to the field of nanomedicine, especially in drug/gene delivery systems, multimodal imaging, biosensing, antimicrobial agents and tissue engineering. 2D nanomaterials such as graphene/graphene oxide (GO)/reduced graphene oxide (rGO), silicate clays, layered double hydroxides (LDHs), transition metal dichalcogenides (TMDs), transition metal oxides (TMOs), black phosphorus (BP), graphitic carbon nitride (g-C₃N₄), hexagonal boron nitride (h-BN), antimonene (AM), boron nanosheets (B NSs) and tin telluride nanosheets (SnTe NSs) possess excellent physical, chemical, optical and biological properties due to their uniform shapes, high surface-to-volume ratios and surface charge. In this review, we first introduce the properties, structures and synthetic strategies of different configurations of 2D nanomaterials. Recent advances and paradigms of 2D nanomaterials in a variety of biomedical applications, ranging from drug delivery, cancer treatment, bioimaging and tissue engineering to biosensing are discussed afterwards. In the final part, we foresee the development prospects and challenges of 2D nanomaterials after summarizing the research status of ultrathin 2D nanomaterials.

Photoelectric-Responsive Extracellular Matrix for Bone Engineering

Using noninvasive stimulation of cells to control cell fate and improve bone regeneration by optical stimulation can achieve the aim of precisely orchestrating biological activities. In this study, we create a fast and repeatable photoelectric-responsive microenvironment around an implant using a bismuth sulfide/hydroxyapatite (BS/HAp) film. The unexpected increase of photocurrent on the BS/HAp film under near-infrared (NIR) light is mainly due to the depletion of holes through PO₄^3- from HAp and interfacial charge transfer by HAp compared with BS. The electrons activate the Na⁺ channel of mesenchymal stem cells (MSCs) and change the cell adhesion in the intermediate environment. The behavior of MSCs is tuned by changing the photoelectronic microenvironment. RNA sequencing reveals that when photoelectrons transfer to the cell membrane, sodium ions flux and the membrane potential depolarizes to change the cell shape. Meanwhile, calcium ions fluxed and FDE1 was upregulated. Furthermore, the TCF/LEF in the cell nucleus began transcription to regulate the downstream genes involved in osteogenic differentiation, which is performed through the Wnt/Ca²⁺ signaling pathway. This research has created a biological therapeutic strategy, which can achieve in vitro remotely, precisely, and noninvasively controlling cell differentiation behaviors by tuning the in vivo photoelectric microenvironment using NIR light.

Preparation of injectable temperature-sensitive chitosan-based hydrogel for combined hyperthermia and chemotherapy of colon cancer

The purpose of this study was to design an injectable hydrogel with temperature-sensitive property for safe and high efficient in vivo colon cancer hyperthermia and chemotherapy. Chitosan (CS) solution was injected into the tumor at room temperature and automatically gelled after warming to body temperature in the present of β-glycerophosphate (β-GP). Combined localized tumor photothermal and chemotherapy were achieved by dissolving photothermal material MoS2/Bi2S3-PEG (MBP) nanosheets and drug molecule doxorubicin (DOX) into the hydrogel, and the gel system could encapsulate DOX and MBP nanosheets and prevent them from entering the blood circulation and damaging normal tissues and cells. More importantly, the CS/MBP/DOX (CMD) hydrogel exhibited a photothermal efficiency of 22.18% and 31.42% in the first and second near infrared light (NIR I and NIR II) biowindows respectively at a low MBP concentration (0.5 mg/mL). Besides, the release of the DOX from CMD hydrogel was controllable since the gel temperature could be governed by NIR laser irradiation. Moreover, the chitosan-based hydrogel had antibacterial effects. The designed composite hydrogel is anticipated to act as a platform for the high efficient treatment of tumors owing to the different penetration depths of NIR I and NIR II.

Rapid Biofilm Elimination on Bone Implants Using Near-Infrared-Activated Inorganic Semiconductor Heterostructures

Bacterial infections often cause orthopedic surgery failures. It is hard for the immune system and antibiotics to clear bacteria adhered to implants after they form a mature biofilm, and a secondary surgery is required to remove the infected implants. To avoid this, a hybrid coating of Bi₂ S₃ @Ag₃ PO₄ /Ti is prepared to eliminate biofilm using near-infrared (NIR) light. Bi₂ S₃ nanorod (NR) arrays are prepared on titanium (Ti) implants through hydrothermal methods, and Ag₃ PO₄ nanoparticles (NPs) are loaded on Bi₂ S₃ NR arrays using a stepwise electrostatic adsorption strategy. The introduction of Ag₃ PO₄ NPs enhances the photocatalysis performances of Bi₂ S₃ , and the hybrid coating also exhibits good photothermal effects. After 808 nm light irradiation for 15 min, it shows superior bactericidal efficiency of 99.45% against Staphylococcus aureus, 99.74% against Escherichia coli in vitro, and 94.54% against S. aureus biofilm in vivo. Bi₂ S₃ @Ag₃ PO₄ /Ti also shows good cell viability compared to pure Ti. This NIR-activated-inorganic hybrid semiconductor heterojunction coating is biocompatible and could be employed to eliminate biofilm effectively, which makes it a very promising strategy for the surface modification of bone implant materials.

Electrostatic Self-Assembly of Ti3C2Tx MXene and Gold Nanorods as an Efficient Surface-Enhanced Raman Scattering Platform for Reliable and High-Sensitivity Determination of Organic Pollutants

A reliable surface-enhanced Raman scattering (SERS) substrate composed of two-dimensional (2D) MXene (Ti₃C₂T_x) nanosheets and gold nanorods (AuNRs) is designed and fabricated for sensitive detection of organic pollutants. The AuNRs are uniformly distributed on the surface of the 2D MXene nanosheets because of the strong electrostatic interactions, forming abundant SERS hot spots. The MXene/AuNR SERS substrate exhibits high sensitivity and excellent reproducibility in the determination of common organic dyes such as rhodamine 6G, crystal violet, and malachite green. The detection limits are 1 × 10^-12, 1 × 10^-12, and 1 × 10^-10 M, and relative standard deviations determined from 13 areas on each sample are 18.1, 10.1, and 15.6%, respectively. In the determination of more complex organic pesticides and pollutants, the substrate also shows excellent sensitivity and quantitative detection, and the detection limits for thiram and diquat of 1 × 10^-10 and 1 × 10^-8 M, respectively, are much lower than the contaminant levels stipulated by the US Environmental Protection Agency. The MXene/AuNR composite constitutes an efficient SERS platform for reliable and high-sensitivity environmental analysis and food safety monitoring.

Two-Dimensional Materials in Biosensing and Healthcare: From In Vitro Diagnostics to Optogenetics and Beyond

Since the isolation of graphene in 2004, there has been an exponentially growing number of reports on layered two-dimensional (2D) materials for applications ranging from protective coatings to biochemical sensing. Due to the exceptional, and often tunable, electrical, optical, electrochemical, and physical properties of these materials, they can serve as the active sensing element or a supporting substrate for diverse healthcare applications. In this review, we provide a survey of the recent reports on the applications of 2D materials in biosensing and other emerging healthcare areas, ranging from wearable technologies to optogenetics to neural interfacing. Specifically, this review provides (i) a holistic evaluation of relevant material properties across a wide range of 2D systems, (ii) a comparison of 2D material-based biosensors to the state-of-the-art, (iii) relevant material synthesis approaches specifically reported for healthcare applications, and (iv) the technological considerations to facilitate mass production and commercialization.

Ultrasound assisted one-step synthesis of Au@Pt dendritic nanoparticles with enhanced NIR absorption for photothermal cancer therapy

Near-infrared (NIR) light-mediated non-invasive photothermal therapy (PTT) has attracted considerable attention for cancer treatment. Strong optical absorption located in the NIR region and high performance in converting light to heat should be emphasized for the development of ideal photothermal agents. In this report, Au@Pt bimetallic nanoparticles (Au@Pt NPs) with dendritic structure were synthesized through an ultrasound assisted one-step method in aqueous solution. The absorption of Au@Pt NPs at 808 nm was obviously enhanced compared to that of Au NPs and could be easily manipulated via the amount of Pt NPs. Au@Pt NPs exhibited excellent photostability with a photothermal conversion efficiency of 44.2%, which is significantly higher than those in most reported studies. Au@Pt NPs with thiol PEG functionalization presented improved cellular killing capacity upon NIR laser irradiation. Moreover, the potential application of Au@Pt NPs was also investigated in xenograft tumor mouse model. Overall, the remarkable therapeutic characteristics of PEGylated Au@Pt NPs provide them with great potential for future cancer treatment.

Highly Effective and Noninvasive Near-Infrared Eradication of a Staphylococcus aureus Biofilm on Implants by a Photoresponsive Coating within 20 Min

Biofilms have been related to the persistence of infections on medical implants, and these cannot be eradicated because of the resistance of biofilm structures. Therefore, a biocompatible phototherapeutic system is developed composed of MoS2, IR780 photosensitizer, and arginine-glycine-aspartic acid-cysteine (RGDC) to safely eradicate biofilms on titanium implants within 20 min. The magnetron-sputtered MoS2 film possesses excellent photothermal properties, and IR780 can produce reactive oxygen species (ROS) with the irradiation of near-infrared (NIR, λ = 700-1100 nm) light. Consequently, the combination of photothermal therapy (PTT) and photodynamic therapy (PDT), assisted by glutathione oxidation accelerated by NIR light, can provide synergistic and rapid killing of bacteria, i.e., 98.99 ± 0.42% eradication ratio against a Staphylococcus aureus biofilm in vivo within 20 min, which is much greater than that of PTT or PDT alone. With the assistance of ROS, the permeability of damaged bacterial membranes increases, and the damaged bacterial membranes become more sensitive to heat, thus accelerating the leakage of proteins from the bacteria. In addition, RGDC can provide excellent biosafety and osteoconductivity, which is confirmed by in vivo animal experiments.

Biomedical and bioimaging applications of 2D pnictogens and transition metal dichalcogenides

Multifunctional platforms will play a key role and gain more prominence in the field of personalized healthcare worldwide in the near future due to the ever-increasing number of patients suffering from cancer. Along with the development of efficient techniques for cancer treatment, a considerable effort should be devoted toward the exploration of an emerging class of materials with unique properties that might be beneficial in this context. Currently, 2D post-carbon materials, such as pnictogens (phosphorene, antimonene), transition metal dichalcogenides, and boron nitride, have become popular due to their efficient photothermal behavior, drug-loading capability, and low toxicity. This review underlines the recent progresses made in the abovementioned 2D materials for photothermal/photodynamic cancer therapies and their applicability in bioimaging applications.

Multifunctional two-dimensional nanocomposites for photothermal-based combined cancer therapy

Two-dimensional (2D) nanocomposites have been widely used in biomedical applications during the past few years due to their extraordinary physicochemical properties, which has proved their importance in the field of nanomedicine. Benefiting from the excellent optical absorption in the near-infrared window and large specific surface area, many efforts have been devoted to fabricating 2D nanomaterial-based multifunctional nanoplatforms to realize photothermal therapy (PTT)-based or chemotherapy-based synergistic treatment, which exhibits obvious anti-tumor effects and significantly enhances the therapeutic efficiency of cancer compared with monotherapy. In particular, 2D nanocomposites are usually fabricated as intelligent nanoplatforms for stimuli-responsive nanocarriers, whose therapeutic effects could be specifically activated by the tumor microenvironment (TME). In addition, different fluorescent probes and functional inorganic nanomaterials could be absorbed on the surface of 2D nanomaterials to fabricate multifunctional hybrid nanomaterials with satisfactory magnetic, optical, or other properties that are widely used for multimodal imaging-guided cancer therapy. In this review, the latest development of multifunctional 2D nanocomposites for combination therapy is systematically summarized, mainly focusing on PTT-based synergistic cancer therapy, and the other forms and potential forms of synergistic cancer therapy are also simply summarized. Furthermore, the design principles of 2D nanocomposites are particularly emphasized, and the current challenges and future prospects of 2D nanocomposites for cancer theranostics are discussed simultaneously.

Boosting Cancer Therapy with Organelle-Targeted Nanomaterials

The ultimate goal of cancer therapy is to eliminate malignant tumors while causing no damage to normal tissues. In the past decades, numerous nanoagents have been employed for cancer treatment because of their unique properties over traditional molecular drugs. However, lack of selectivity and unwanted therapeutic outcomes have severely limited the therapeutic index of traditional nanodrugs. Recently, a series of nanomaterials that can accumulate in specific organelles (nucleus, mitochondrion, endoplasmic reticulum, lysosome, Golgi apparatus) within cancer cells have received increasing interest. These rationally designed nanoagents can either directly destroy the subcellular structures or effectively deliver drugs into the proper targets, which can further activate certain cell death pathways, enabling them to boost the therapeutic efficiency, lower drug dosage, reduce side effects, avoid multidrug resistance, and prevent recurrence. In this Review, the design principles, targeting strategies, therapeutic mechanisms, current challenges, and potential future directions of organelle-targeted nanomaterials will be introduced.

In vivo clearable inorganic nanophotonic materials: designs, materials and applications

Inorganic nanophotonic materials (INPMs) are considered to be promising diagnosis and therapeutic agents for in vivo applications, such as bio-imaging, photoacoustic imaging and photothermal therapy. However, some concerns remain regarding these materials, such as undesirable long-term in vivo accumulation and associated toxicity. The inability to be degraded or cleared has decreased their likelihood to be used for potential clinical translations. To this end, new strategies have recently emerged to develop systematically clearable INPMs. Thus, this review provides an overview of these strategies used to expedite the clearance of INPMs, as well as the relevant design and functionalized modifications which are available to engineer the above materials. Along with their important applications in the fields of in vivo diagnoses and therapies, the challenges and outlook for in vivo clearable INPMs are also discussed. This attempt to explore in vivo clearable INPMs to inhibit their accumulation toxicity may represent the solution to a ubiquitous physiological issue, thus paving a new avenue for the development of novel optical nanomaterials for biophotonic applications.

Self-Assembled 2D Glycoclusters for the Targeted Delivery of Theranostic Agents to Triple-Negative Breast Cancer Cells

Triple-negative breast cancer (TNBC) is a devastating disease worldwide, for which targeted imaging and therapeutic agents remain elusive. There has been growing awareness that carbohydrates are valuable as drug candidates and targeting agents for a variety of human diseases, including cancers that overexpress carbohydrate receptors on the cell surface. Here, we develop a two-dimensional (2D) glycocluster by means of simple, stepwise self-assembly for the targeted delivery of theranostic agents to TNBC cells that express mannose receptors (MRs) on the cell surface. Human serum albumin, which contains a variety of hydrophobic pockets capable of accommodating small molecules, was used to simultaneously encapsulate a mannose-based glycoprobe and a commercial photosensitizer (i.e., Ce6). The multicomponent "neoglycoprotein" formed was used to self-assemble with 2D MnO2, producing 2D glycoclusters, which could be selectively internalized by a TNBC cell line (MDA-MB-231) as facilitated by binding to the transmembrane MR. The intracellular degradation of the 2D MnO2 backbone by biothiols then released Ce6 for cell imaging and, subsequently, photodynamic therapy. This study provides insights into the development of carbohydrate-based materials for targeted, stimuli-responsive theranostics of TNBC.

Organic Nanotheranostics for Photoacoustic Imaging-Guided Phototherapy

Phototherapies including photothermal therapy (PTT) and photodynamic therapy (PDT) have emerged as one of the avant-garde strategies for cancer treatment. Photoacoustic (PA) imaging is a new hybrid imaging modality that shows great promise for real-time in vivo monitoring of biological processes with deep tissue penetration and high spatial resolution. To enhance therapeutic efficacy, reduce side effects and minimize the probability of over-medication, it is necessary to use imaging and diagnostic methods to identify the ideal therapeutic window and track the therapeutic outcome. With this regard, nanotheranostics with the ability to conduct PA imaging and PTT/PDT are emerging. This review summarizes the recent progress of organic nanomaterials including nearinfrared (NIR) dyes and semiconducting polymer nanoparticles (SPNs) in PA imaging guided cancer phototherapy, and also addresses their present challenges and potential in clinical applications.

Flower-like Fe7S8/Bi2S3 superstructures with improved near-infrared absorption for efficient chemo-photothermal therapy

Although various photothermal therapy (PTT) nanoagents have been developed in recent years, the rational design and easy synthesis of a PTT nanoplatform with improved near-infrared (NIR) absorption have remained challenging. Herein, via a facile one-pot solvothermal strategy, hydrophilic nanosheet-assembled flower-like Fe7S8/Bi2S3 superstructures were fabricated successfully. Such nanoflowers exhibit improved NIR absorption, which is 1.54 times higher than that of pure Bi2S3 nanosheets at a wavelength of 808 nm. Attractively, these nanoflowers could serve as a drug delivery carrier with controlled release under pH/NIR stimuli and display a fascinating chemo-photothermal synergetic therapeutic effect both in vitro and vivo. The resulting nanoflowers may open up a way for the design of other nanoagents with an improved NIR absorption and chemo-photothermal cancer therapy effect.

On-Demand Detaching Nanosystem for the Spatiotemporal Control of Cancer Theranostics

Engineering multiple theranostic modalities into a single nanoscale entity holds great potential to rejuvenate cancer treatments; however, enabling the sophisticated spatiotemporal control of each component for maximizing theranostic improvement and minimizing side effects concurrently remains a challenge. Herein, an intelligent detachable "nanorocket" is developed to sequentially manipulate and optimize multitheranostic processes for magnetic resonance-assisted ultrasound-drug combined therapy (MR-HIFU-Drug). The "nanorocket" is constructed by integrating multicomponent (MnCO₃, doxorubicin, silica) on the pH-sensitive CaCO₃ nanoparticles step by step via cation exchange and controlled heterogeneous nucleation, in which doxorubicin is encapsulated in both carbonates and silica component. The "nanorocket" can initiate sequential detachment in the acidic tumor microenvironment. Specifically, carbonates decompose instantly, releasing Mn²⁺ as the MR contrast agent and leaving hollow silica nanostructure behind as the HIFU synergistic agent. Consequently, burst release of drug is also triggered, further triggering the degradation of silica, which in turn regulates the slow release of drug from the silica matrix. Thus, efficient tumor inhibition is achieved by enhanced HIFU ablation and biphase release of doxorubicin with a stepwise clearance of Mn and Si. This work establishes a system for the systematic spatiotemporal dispatch of diverse theranostic components for the balance of efficacy and safety in cancer theranostics.

One-pot synthesis of polypyrrole nanoparticles with tunable photothermal conversion and drug loading capacity

With an excellent near-infrared (NIR) light-responsive property, polypyrrole (PPy) nanoparticle has emerged as a promising NIR photothermal transducing agent for tumor photothermal therapy (PTT). Herein, we reported the PVP mediated one-pot synthesis of colloidal stable and biocompatible PPy nanoparticles (PPy-PVP NPs) for combined tumor photothermal-chemotherapy. The influence of molecular weight and PVP concentration on the spectroscopic characteristic, photothermal feature, drug loading performance, and antitumor efficiency of the resultant PPy-PVP NPs was systematically studied. By choosing PVP with a molecular weight of 360 kDa (concentration of 5 mg/mL) as the template and surface modifier during the synthesis, PPy-PVP NPs with optimal spectroscopic characteristic, photothermal feature, drug loading performance, and antitumor efficiency were synthesized. Findings in this study are anticipated to provide an in-depth understanding of the important character of surface engineering in the rational design and biomedical applications of PPy NPs.

Single-Component Bismuth Nanoparticles as a Theranostic Agent for Multimodal Imaging-Guided Glioma Therapy

Single-component nanomaterials such as bismuth (Bi) based on nanoparticles (NPs) intrinsically having both diagnostic and therapeutic capabilities are widely needed in biomedical fields. However, their design and fabrication still face enormous challenges. Here, a kind of pure Bi NPs with ultrahigh X-ray attenuation coeffcient was developed and evaluated as a simple but powerful theranostic nanomaterals and potent light-to-heat conversion efficiency for photoacuostic imaging (PAI)/photothermal therapy (PTT) in this study. The prepared pure Bi NPs showed excellent photothermal performance and the temperature of NPs solution (1 mg/mL) increased to 70 °C under near-infrared light irradiation within 4 min. The pure Bi NPs showed obvious enhancement effect both in X-ray computed tomography (CT) and PA imaging modalities in vivo. In addition, the glioma growth was efficiently suppressed by the pure Bi NPs after 808 nm laser irradiation, while maintained the biosafety and low toxicity. Thus, it is notable that this type of Bi nanomaterial has great potential in multi-imaging guided cancer treatment.

Inlaying Radiosensitizer onto the Polypeptide Shell of Drug-Loaded Ferritin for Imaging and Combinational Chemo-Radiotherapy

Rationale: Ferritin with unique hollow cavity is an emerging protein-based nanoplatform for anticancer-drug delivery, but the in vivo chemotherapeutic effectiveness is still unsatisfactory with such a monotherapy modality, which is urgently in need of improvement. Methods: Here a novel ferritin nanotheranostic with anticancer-drug doxorubicin encapsulated into its hollow interior and nanoradiosensitizer bismuth sulfide nanocrystals inlayed onto its polypeptide shell was synthesized for combinational therapeutic benefits. The formation mechanism of bismuth sulfide nanocrystals based on ferritin has been analyzed. The in vitro and in vivo treatment effects were carried out on HeLa cancer cells and tumor-bearing mice, respectively. The biocompatibility and excretion of the ferritin nanotheranostic have also been evaluated to guarantee their biosafety. Results: The polypeptide shell of ferritin provides nucleation sites for the bismuth sulfide nanocrystals through coordination interaction, and simultaneously inhibits the further growth of bismuth sulfide nanocrystals, rendering the bismuth sulfide nanocrystals like rivets inlaying onto the polypeptide firmly, which can not only strengthen the architectural stability of ferritin to prevent drug burst leakage during systemic circulation, but also act as excellent computed tomography contrast agents and nanoradiosensitizers for in vivo imaging-guided cancer combinational treatments. Conclusions: The design concept of inlaying bismuth sulfide nanocrystals onto the polypeptide shell of doxorubicin-encapsulated ferritin significantly inhibits the tumor growth and simultaneously further broadens the application of ferritin in nanomedicine.

Carbon dot-sensitized MoS2 nanosheet heterojunctions as highly efficient NIR photothermal agents for complete tumor ablation at an ultralow laser exposure

Currently, one of the major hurdles hindering the clinical applications of photothermal therapy (PTT) and photothermal-chemo combination therapy (PCT) is the lack of highly efficient, readily derived, and irradiation-safe photothermal agents in the biologically transparent window. Herein, we report the first design and rational construction of 0D/2D/0D sandwich heterojunctions for greatly enhanced PTT and PCT performances using 0D N-doped carbon dots and 2D MoS2 nanosheets as the assembly units. The well-matching heterojunctions enabled an additional enhancement in NIR absorbance owing to the carrier injection from carbon dots to MoS2 nanosheets, and achieved a much higher photothermal conversion efficiency (78.2%) than that of single NIR-CDs (37.6%) and MoS2 (38.3%) only. In virtue of the heterojunction-based PTT, complete tumor recession without recurrence or pulmonary metastasis was realized at an ultralow and safe laser exposure (0.2 W cm-2) below the skin tolerance irradiation threshold. Furthermore, by taking advantage of the strong X-ray attenuation and effective drug loading capacity of MoS2 nanosheets, the CT imaging-guided PCT was achieved at 0.1 W cm-2, without inducing noticeable toxic side effects. Our findings can substantiate the potential of a novel 0D/2D heterojunction for cancer theranostics.

Enhanced radiosensitization of ternary Cu3BiSe3 nanoparticles by photo-induced hyperthermia in the second near-infrared biological window

The development of a new multifunctional nanomedicine capable of enhancing radiosensitization by photo-induced hyperthermia for the inhibition of cancer growth and metastasis is highly required for efficient treatment of cancer cells. Compared to the first near-infrared (NIR) window, the second NIR window light could provide a maximum penetration depth as well as minimizing autofluorescence due to its low scattering and energy absorption. Here, we report a new versatile theranostic agent based on ternary Cu3BiSe3 nanoparticles (NPs) modified by poly(vinylpyrollidone) (PVP-Cu3BiSe3). Benefiting from their preferable X-ray attenuation ability and strong NIR absorbance in the second NIR biological window, PVP-Cu3BiSe3 NPs can not only deposit more radiation doses to destroy the cancer cells, but also conduct the optical energy into hyperthermia for thermal eradication of tumor tissues and the improvement of the tumor oxygenation to overcome the hypoxia-associated radio-resistance of tumors. According to both in vitro and in vivo results, exposure to an X-ray plus 1064 nm laser completely kills cancer cells and even inhibits tumor metastasis, displaying no warning signs of a relapse. On the other hand, PVP-Cu3BiSe3 NPs can be used as a multi-model imaging agent for X-ray computer tomography (CT) and photoacoustic tomography (PAT) imaging. These demonstrate the potential of PVP-Cu3BiSe3 NPs in multimodal imaging-guided synergetic radiophotothermal therapy of deep-seated tumors and effective inhibition of their metastasis.

Photothermal therapy and photoacoustic imaging via nanotheranostics in fighting cancer

The nonradiative conversion of light energy into heat (photothermal therapy, PTT) or sound energy (photoacoustic imaging, PAI) has been intensively investigated for the treatment and diagnosis of cancer, respectively. By taking advantage of nanocarriers, both imaging and therapeutic functions together with enhanced tumour accumulation have been thoroughly studied to improve the pre-clinical efficiency of PAI and PTT. In this review, we first summarize the development of inorganic and organic nano photothermal transduction agents (PTAs) and strategies for improving the PTT outcomes, including applying appropriate laser dosage, guiding the treatment via imaging techniques, developing PTAs with absorption in the second NIR window, increasing photothermal conversion efficiency (PCE), and also increasing the accumulation of PTAs in tumours. Second, we introduce the advantages of combining PTT with other therapies in cancer treatment. Third, the emerging applications of PAI in cancer-related research are exemplified. Finally, the perspectives and challenges of PTT and PAI for combating cancer, especially regarding their clinical translation, are discussed. We believe that PTT and PAI having noteworthy features would become promising next-generation non-invasive cancer theranostic techniques and improve our ability to combat cancers.

Artificial intelligence in nanomedicine

The field of nanomedicine has made substantial strides in the areas of therapeutic and diagnostic development. For example, nanoparticle-modified drug compounds and imaging agents have resulted in markedly enhanced treatment outcomes and contrast efficiency. In recent years, investigational nanomedicine platforms have also been taken into the clinic, with regulatory approval for Abraxane® and other products being awarded. As the nanomedicine field has continued to evolve, multifunctional approaches have been explored to simultaneously integrate therapeutic and diagnostic agents onto a single particle, or deliver multiple nanomedicine-functionalized therapies in unison. Similar to the objectives of conventional combination therapy, these strategies may further improve treatment outcomes through targeted, multi-agent delivery that preserves drug synergy. Also, similar to conventional/unmodified combination therapy, nanomedicine-based drug delivery is often explored at fixed doses. A persistent challenge in all forms of drug administration is that drug synergy is time-dependent, dose-dependent and patient-specific at any given point of treatment. To overcome this challenge, the evolution towards nanomedicine-mediated co-delivery of multiple therapies has made the potential of interfacing artificial intelligence (AI) with nanomedicine to sustain optimization in combinatorial nanotherapy a reality. Specifically, optimizing drug and dose parameters in combinatorial nanomedicine administration is a specific area where AI can actionably realize the full potential of nanomedicine. To this end, this review will examine the role that AI can have in substantially improving nanomedicine-based treatment outcomes, particularly in the context of combination nanotherapy for both N-of-1 and population-optimized treatment.

Energy-Converting Nanomedicine

Serious side effects to surrounding normal tissues and unsatisfactory therapeutic efficacy hamper the further clinic applications of conventional cancer-therapeutic strategies, such as chemotherapy and surgery. The fast development of nanotechnology provides unprecedented superiorities for cancer therapeutics. Externally activatable therapeutic modalities mediated by nanomaterials, relying on highly effective energy transformation to release therapeutic elements/effects (cytotoxic reactive oxygen species, thermal effect, photoelectric effect, Compton effect, cavitation effect, mechanical effect or chemotherapeutic drug) for cancer therapies, categorized and termed as "energy-converting nanomedicine," have arouse considerable concern due to their noninvasiveness, desirable tissue-penetration depth, and accurate modulation of therapeutic dose. This review summarizes the recent advances in the engineering of intelligent functional nanotherapeutics for energy-converting nanomedicine, including photo-based, radiation-based, ultrasound-based, magnetic field-based, microwave-based, electric field-based, and radiofrequency-based nanomedicines, which are enabled by external stimuli (light, radiation, ultrasound, magnetic field, microwave, electric field, and radiofrequency). Furthermore, biosafety issues of energy-converting nanomedicine related to future clinical translation are also addressed. Finally, the potential challenges and prospects of energy-converting nanomedicine for future clinical translation are discussed.

Hypoxia-Irrelevant Photonic Thermodynamic Cancer Nanomedicine

The hypoxic tumor microenvironment severely lowers the therapeutic efficacy of oxygen-dependent anticancer modalities because tumor hypoxia hinders the generation of toxic reactive oxygen species. Here we report a thermodynamic cancer-therapeutic modality that employs oxygen-irrelevant free radicals generated from thermo-labile initiators for inducing cancer cell death. A free radical nanogenerator was engineered via direct growth of mesoporous silica layer onto the surface of two-dimensional Nb₂C MXene nanosheets toward multifunctionality, where the mesopore provided the reservoirs for initiators and the MXene core acted as the photonic-thermal trigger at the near-infrared-II biowindow (NIR-II). Upon illumination by a 1064 nm NIR-II laser, the photothermal-conversion effect of Nb₂C MXene induced the fast release and quick decomposition of the encapsulated initiators (AIPH) to produce free radicals, which promoted cancer cell apoptosis in both normoxic and hypoxic microenvironment. Systematic in vitro and in vivo evaluations have demonstrated the synergistic-therapeutic outcome of this intriguing photonic nanoplatform-enabled thermodynamic cancer therapy for completely eradicating the 4T1 tumors without recurrence by NIR-II laser irradiation. This work pioneers the thermodynamic therapy for oxygen-independent cancer treatment by photonic triggering at the NIR-II biowindow.

MoS2 flakes stabilized with DNA/RNA nucleotides: In vitro cell response

Two-dimensional transition metal dichalcogenides (TMDCs), such as MoS₂ and WS₂, have recently emerged as nanomaterials with potential use in biomedicine. An attractive means to favor their interaction with biological media is the use of proper biomolecules as exfoliating/dispersing agents. Here, MoS₂ flakes were stabilized with different small functional biomolecules such as adenosine monophosphate (AMP), guanosine monophosphate (GMP) and flavin mononucleotide (FMN) through the strong nucleotide-MoS₂ interaction of Lewis acid-base type, rather than just on the weak dispersive and hydrophobic forces commonly associated with the use of many surfactants. The impact of the nucleotide-stabilized MoS₂ flakes on the viability and cell proliferation, on the production of intracellular reactive oxygen species (ROS), and on the preosteoblast differentiation process (early stage) has been also evaluated, as well as the incorporation and intracellular localization of the nanomaterials by MC3T3-E1 and Saos-2 cells. The nucleotide-stabilized MoS₂ flakes were found to exhibit excellent biocompatibility. Furthermore, their incorporation did not affect the integrity of the cell plasma membrane, which makes them ideal candidates for delivering drug/gene directly into cells. The in vitro cell response of tumor cells to these nanomaterials differs from that of undifferentiated cells, which provides the basis for their potential use in cancer therapy.