A Borondifluoride-Complex-Based Photothermal Agent with an 80 % Photothermal Conversion Efficiency for Photothermal Therapy in the NIR-II Window

Reprogrammed glycolysis-induced augmentation of NIR-II excited photodynamic/photothermal therapy

Small molecule-based multifunctional optical diagnostic materials have garnered considerable interest due to their highly customizable structures, tunable excited-state properties, and remarkable biocompatibility. We herein report the synthesis of a multifaceted photosensitizer, PPQ-CTPA, which exhibits exceptional efficacy in generating Type I reactive oxygen species (ROS) and thermal energy under near-infrared-II (NIR-II, >1000 nm) laser excitation at 1064 nm, thereby combining photodynamic therapy (PDT) and photothermal therapy (PTT) functionalities. To enhance therapeutic efficacy, we engineered lonidamine (LND) by conjugating it with triphenylphosphonium (TPP) cations, producing LND-TPP. This compound inhibits mitochondrial glycolysis and downregulates heat shock protein 90 (HSP 90) levels in a breast cancer mouse model, potentiating both PDT and PTT. For in vivo applications, PPQ-CTPA and LND-TPP are encapsulated within the amphiphilic polymer DSPE-SS-PEG to obtain PPQ-CTPAL NPs. In breast cancer cell lines, PPQ-CTPAL NPs are decomposed by cellular GSH, simultaneously releasing the dual-functioning photosensitizer PPQ-CTPL and the mitochondria-disrupting agent LND-TPP. Upon 1064 nm laser irradiation, we found that tumor growth in breast cancer mice is effectively restrained by PPQ-CTPAL NPs. This work highlights the synergistic integration of PDT, PTT, and chemotherapy facilitated by NIR-II fluorescence, photoacoustic, and photothermal imaging under 1064 nm irradiation, underscoring the clinical potential of multifunctional phototherapeutic agents.

Supramolecular nanoagent as a dual-blocked thermoresistance inhibitor for effective mild-temperature photothermal therapy

Mild-temperature (<45 °C) photothermal therapy (PTT) is a promising approach to kill cancer cells by inhibiting the expression of heat shock proteins (HSPs) related to thermoresistance, a method commonly applied in most mild-temperature PTT studies. Regrettably, thermoresistance cannot be fully suppressed solely by inhibiting HSPs. Under normal conditions, heat shock factor 1 (HSF-1) remains inactive and forms a complex with HSPs. However, HSF-1 can dissociate from the complex and be activated, leading to the continuous production of significant amounts of HSPs, which in turn triggers thermoresistance upon heating. Therefore, simultaneously inhibiting both HSPs and HSF-1 activities presents a more effective strategy for developing mild-temperature PTT than only inhibiting HSPs. In this work, we focus on the complete blocking of thermoresistance to create a novel supramolecular nanoagent, IQ@NPs, for mild-temperature PTT. IQ@NPs demonstrated excellent drug release, tumor accumulation, and photothermal conversion, resulting in a rapid increase in the temperature of tumor sites to 42.9 °C within 5 min of irradiation. Western blotting revealed that IQ@NPs significantly inhibited the expression of HSPs (HSP90) and HSF-1. After 15 d treatment, tumor growth was significantly suppressed by IQ@NPs through effective mild-temperature PTT. Furthermore, IQ@NPs exhibited satisfactory safety and minimal side effects. This study represents a progressive advancement in mild-temperature PTT.

Smart hydrogel: A new platform for cancer therapy

Cancer is a significant contributor to mortality worldwide, posing a significant threat to human life and health. The unique bioactivity, ability to precisely control drug release, and minimally invasive properties of hydrogels are indispensable attributes that facilitate optimal performance in cancer therapy. However, conventional hydrogels lack the ability to dynamically respond to changes in the surrounding environment, withstand drastic changes in the microenvironment, and trigger drug release on demand. Therefore, this review focuses on smart-responsive hydrogels that are capable of adapting and responding to external stimuli. We comprehensively summarize the raw materials, preparation, and cross-linking mechanisms of smart hydrogels derived from natural and synthetic materials, elucidate the response principles of various smart-responsive hydrogels according to different stimulation sources. Further, we systematically illustrate the important role played by hydrogels in modern cancer therapies within the context of therapeutic principles. Meanwhile, the smart hydrogel that uses machine learning to design precise drug delivery has shown great prospects in cancer therapy. Finally, we present the outlook on future developments and make suggestions for future related work. It is anticipated that this review will promote the practical application of smart hydrogels in cancer therapy and contribute to the advancement of medical treatment.

An all-in-one PEGylated NIR-II conjugated polymer for high-resolution blood circulation imaging and photothermal immunotherapy

Fluorescence imaging in the second near-infrared window (NIR-II) has shown tremendous potential for in vivo monitoring of biological processes, offering high spatial resolution and real-time imaging capabilities. Conjugated polymers, commonly used as photothermal agents (PTAs) in photothermal therapy, have emerged as promising candidates for NIR-II imaging. However, their imaging efficiency is compromised by aggregation, which arises from strong π-π stacking interactions between their extended π-conjugated backbones. In this work, we designed a novel conjugated polymer (CP) and developed an integrated nanoplatform (CPN-PEGnk, n = 2 or 5) through PEGylation. Notably, CPN-PEG5k exhibited a red-shift in NIR absorption along with a marked increase in NIR-II fluorescence intensity (2.97 folds greater) compared to physically encapsulated nanoparticles (F127@CPN). Furthermore, CPN-PEG5k retained a remarkable photothermal conversion efficiency of up to 58.6%. The exceptional NIR-II imaging performance of CPN-PEG5k was validated in detailed blood circulation imaging in mice, with a signal-to-background ratio of 8.9. In addition, in a breast cancer mouse model, CPN-PEG5k successfully eradicated tumors and stimulated immune responses, effectively suppressing tumor progression and metastasis. These findings underscore the potential of CPN-PEG5k in advancing conjugated polymer applications for NIR-II imaging.

Zinc phthalocyanine and sulfasalazine coloaded nanoaggregates with Prussian blue functionalization for sensitizing tumor photothermal/photodynamic therapy

Photothermal therapy/photodynamic therapy (PTT/PDT), as a noninvasive therapeutic modality, has been extensively applied in superficial tumor treatment. However, their curative effects were largely weakened due to hypoxia and an elevated glutathione (GSH) microenvironment. Herein, zinc phthalocyanine (ZnPc) and sulfasalazine (SAS) coloaded nanoaggregates (Z-S@B NAs) with Prussian blue (PB) functionalization (PB/Z-S@B NAs) were fabricated via self-assembly and using an in situ oxidative polymerization method for tumor PTT/PDT sensitization. The designed PB/Z-S@B NAs were capable of triggering local hyperthermia and generating substantial reactive oxygen species (ROS) under 660- and 808-nm laser irradiation. Notably, the PB/Z-S@B NAs exhibited favorable catalase-like (CAT-like) activity that decomposed hydrogen peroxide into oxygen, which further enhanced tumor cell sensitivity to PTT/PDT. Moreover, SAS from the PB/Z-S@B NAs remarkably decreased the antioxidant GSH level, resulting in a synergetic tumor-killing effect. Collectively, this study provides a versatile nanoplatform to overcome intrinsic antitumor effect and enhance tumor sensitivity to PTT/PDT.

NIR-II D-A-D-Type Small-Molecule Coordination with Carboxylatopillar[5]Arene: a Multifunctional Phototheranostic for Low-Temperature NIR-II Photothermal/Platinum-Based/Chemodynamic Combination Cancer Immunotherapy

Low-temperature second near-infrared region (NIR-II) photothermal therapy (PTT) has shown significant potential in minimizing damage to normal tissues and reducing inflammation. However, it still faces challenge of insufficient immune response. Thus, a multifunctional phototheranostic nanoparticle (BDPB/Pt/Fe@P[5]) is developed by co-loading BDPB, CDHPt, and Fe2⁺ with a pH-sensitive lipid DSPE-PEOz2K. The carboxylatopillar[5]arene (CP[5]) used to construct this nanoparticle exhibits strong host-guest recognition with pyridine salts, alleviating aggregation caused quench (ACQ) effect and enhancing the NIR-II emission of the donor-acceptor-donor (D-A-D)-type organic small molecule (BDPB). CP[5] provides suitable vehicles for encapsulating platinum (IV) prodrugs (CDHPt) and Fe2⁺ ions via metal coordination for controllable reactive oxygen species (ROS) release. Under low-intensity NIR-II laser irradiation and an acidic tumor microenvironment, the nanoparticles degrade, releasing CDHPt and Fe2⁺ ions for platinum-based therapy and chemodynamic therapy (CDT). CDHPt facilitates the direct production of superoxide anions (O₂·⁻) from O₂ and partially converts it into the highly cytotoxic hydroxyl radicals, thereby promoting the Fenton reaction process. The therapeutic efficacy is further synergized by immunogenic cell death (ICD) effect.

A conjugated molecule based on tetra-fused thienoisoindigo ribbon for NIR-II photothermal cancer therapy

Water-soluble nanoparticles (NPs) based on the well-defined 4ThIID molecules, namely 4ThIID NPs, were prepared. Benefiting from the strong NIR-II absorption and high photothermal conversion properties of 4ThIID, the ε1064 × PTCE1064 value of 4ThIID NPs reaches 9.18 × 104, which is the highest value among the reported NIR-II photothermal small molecules. In vivo experiments show that 4ThIID NPs can effectively inhibit the growth of tumors in mouse models under the irradiation of a 1064 nm laser.

Exceptional Near-Infrared II Organic Small Molecule Nanoagent for Photoacoustic/Photothermal Imaging-Guided Highly Efficient Therapy in Cancer

Near-infrared II (NIR-II) photoacoustic (PA)/photothermal imaging-guided tumor therapy holds great promise in precision medicine for cancer treatment. This work reports on the synthesis and application of an organic small molecule nanoagent that has exceptional PA and photothermal properties in the near-infrared region. BCy-TPE was constructed by linking an NIR-II absorbing cyanine dye BCy-Cl with a twisted tetraphenylethene unit. The synthesized BCy-TPE exhibited an intense absorption peak at 1032 nm. After encapsulation into water-dispersible nanoparticles (NPs), BCy-TPE NPs exhibited two absorption peaks at 880 and 1046 nm. Notably, under 1064 nm laser excitation, BCy-TPE NPs deliver a remarkable photothermal conversion efficiency of 92%, together with superior biocompatibility, photostability, and PA/photothermal imaging capability. Moreover, after intravenous administration of BCy-TPE NPs into 4T1 tumor-bearing mice and treatment with safe-intensity (1.0 W cm-2 and 1064 nm) laser irradiation, tumor temperature increased rapidly to 52 °C within 1 min and tumors are completely ablated after a single photothermal therapy treatment. Overall, this work offers a novel strategy to develop superb NIR-II photothermal agents for PA/photothermal imaging-guided highly efficient therapy in cancer.

Photoacoustic Imaging in Inflammatory Orthopedic Diseases: Progress toward Precise Diagnostics and Predictive Regulation

With the intensification of aging issues, inflammatory orthopedic diseases almost occur in the majority of elderly people, which is becoming increasingly severe. Photoacoustic imaging (PAI) is a non-invasive visualization technique for a clear diagnosis of the inflammation areas through detecting acoustic signals generated by the laser irradiation. The combination of "light input" and "acoustic output" provides unprecedented scalability as well as high penetration depth and resolution. This new imaging technology can also present more anatomical information and feedback status of inflammatory activity for the orthopedic diseases. Especially in inflammation imaging, this technology can effectively supplement current clinical imaging methods in diagnosis, staging, and monitoring of pathophysiological processes. With the rapid development of these new technologies, the goals of precise diagnosis, predictive regulation, and ultimately personalized treatment strategies are becoming increasingly realistic. Herein, this article introduces various orthopedic inflammations and related imaging technology applications. It covers the types of PA nanoprobes and their research progress in orthopedic inflammation, as well as the potential applications of PAI in various aspects. The review also discusses the recent researches and emerging translational applications of PAI in orthopedic inflammation, as well as the prospects and future development challenges of clinical transformation.

NIR-II Emissive Persistent Neutral π-Radical with Rapid Doublet Internal Conversion for Efficient Cancer Photothermal Theranostics

Organic radicals are considered prospective materials for near-infrared (NIR) photothermal applications, however, sustainability remains the major obstacle of recently reported ionic radical photothermal agents. This work achieved robust sustainability on a series of neutral π-radicals through rational design donor (D)-acceptor (A). With efficient doublet internal conversion, 10H-spiro(acridine-9,9'-fluorene) (SFA)-BTM presented strong NIR absorption extended to 1000 nm and efficient non-radiative relaxation. SFA-BTM nanoparticles (NPs) realized comparable NIR-I photothermal conversion efficiency (PCE) and photoacoustic sensitivity. Also, the π-radical NPs displayed NIR-II emission and achieved high-resolution whole-body angiography for the first time by the NIR-II bioimaging. Ultimately, the photothermal capabilities are confirmed in an orthotopic bone tumor model by effective ablation of cancer cells in vitro and inhibition of the deterioration of tumor in vivo. This research offers a new horizon in the conception and development of sustainable organic radicals for effective NIR-II imaging and theranostics applications.

Charge regulated pH/NIR dual responsive nanoplatforms centered on cuproptosis for enhanced cancer theranostics

Multifunctional nanoplatforms capable of simultaneously executing multimodal therapy and imaging functions are of great potentials for cancer theranostics. We present an elegantly designed, easy-to-fabricate poly(acrylic acid)/mesoporous calcium phosphate/mesoporous copper phosphate nanosphere (PAA/mCaP/mCuP NS) with outstanding pH/NIR-sensitive multimodal-synergic anti-tumor effects. Optimal porous PAA NS scaffolds were prepared at room temperature by balancing the intra-PAA polymer and polymer-solvents Lennard-Jones potentials in a water:isopropyl alcohol (IPA) mix-solvent. Subsequent sponging of Ca2+ and Cu2+, and adsorption of PO43- to the PAA template were achieved through exquisite electrostatic interactions among ions and the ionizable PAA side-chain in an aqueous environment. This forms the basis for the tumor microenvironment pH-triggered release of Cu2+ to induce cuproptosis, as well as the photothermal effect originating from CuP, while Ca2+ can enhance the nanoplatform's biocompatibility and can damage mitochondria when overloaded. Lastly, PAA/mCaP/mCuP NSs still exhibit high drug loading efficiency for doxorubicin (DOX), enabling chemotherapy. Satisfactory anti-tumor effects of these modalities, along with their synergistic effects, were verified both in vitro and in vivo, with the NSs demonstrating good biodegradation in the latter. The fabricated NS itself holds great promise as an anti-tumor nanomedicine, and the thorough mechanical insights into NS formation may inspire the design of next-generation multifunctional nanoplatforms.

Molecular Engineering of a SICTERS Small Molecule with Superior In Vivo Raman Imaging and Photothermal Performance

Raman-based theranostics has demonstrated great potential for sensitive real-time imaging and treatment. However, these advanced materials, primarily depending on the SERS technique, encounter clinical concerns regarding substrate biosafety. Herein, we molecularly engineered a de novo substrate-free SICTERS small molecule, namely BTT-TPA (bis-thienyl-substituted benzotriazole selenadiazole derivative structures), possessing both ultrasensitive Raman signals and excellent photothermal effects based on self-stacking. The mechanistic studies confirm that BTT maintains the planar structure with polycyclic distorted vibrations required for SICTERS. TPA enhances the donor-acceptor interaction, yielding a Raman sensitivity of BTT higher than previously reported SICTERS molecules; it also acts as a molecular rotor, increasing the photothermal conversion efficiency to 67.44%, which is superior to most of the existing SERS-based photothermal materials. In the tumor model of mouse orthotopic colon cancer, BTT-TPA NPs demonstrate a great Raman imaging-guided photothermal therapy effect in eliminating primary and metastatic tumors, remarkably decreasing the recurrence rate. This work puts forward substrate-free SICTERS small molecules toward Raman-based theranostic applications in vivo.

Rationally designed NIR-II excitable and endoplasmic reticulum-targeted molecular phototheranostics for imaging-guided enhanced photoimmunotherapy of triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a highly aggressive subtype of breast cancer characterized by an extremely poor prognosis. Photoimmunotherapy has emerged as a promising strategy for the treatment of TNBC. This approach works by selectively destroying tumor cells, releasing tumor-associated antigens, activating the immune system, and effectively inhibiting tumor proliferation and metastasis. However, the majority of current phototheranostic approaches are hindered by limited tissue penetration in the first near-infrared (NIR-I) and ultraviolet-visible (UV-Vis) regions. Additionally, due to the lack of specific subcellular targets, it may be difficult to effectively treat deep-seated lesions with ambiguous and extensive boundaries caused by TNBC metastases. Consequently, the development of effective, deep-penetrating, organelle-targeted phototheranostics is essential for enhancing treatment outcomes in TNBC. This work proposes a novel molecular design strategy of NIR-II phototheranostics to realize planar rigid conjugation and alkyl chain functionalization. The di-hexaalkyl chains in a vertical configuration on the donor (4H-cyclopenta[2,1-b:3,4-b'] dithiophene) and shielding units (fluorene) are introduced to construct a S-D-A-D-S type NIR-II phototheranostics (IR-FCD). The planar and rigid structure of IR-FCD exhibits a robust intramolecular charge transfer capability, a lower band gap, enhanced photon absorption properties, and significant steric hindrance from vertically arranged alkyl chains to minimize non-radiative energy loss. By incorporating N-(but-3-yn-1-yl)-4-methylbenzenesulfonamide at the terminus of an elongated alkyl chain, followed by self-assembly into DSPE-S-S-PEG2000, NIR-II excitable phototheranostics (IR-FCD-Ts NPs) with endoplasmic reticulum (ER) targeting capability were successfully synthesized for imaging-guided photoimmunotherapy of TNBC. The IR-FCD-Ts NPs demonstrate exceptional optical characteristics, with maximum absorption at 1068 nm (extending to 1300 nm) and emission at 1273 nm (extending to 1700 nm), along with a high molar absorption coefficient of 2.76*104 L/mol·c at 1064 nm in aqueous solution. Under exposure to 1064 nm laser irradiation, IR-FCD-Ts NPs exhibit superior photothermal properties and have the potential for photodynamic therapy. By targeting ER, thereby inducing ER stress and significantly enhancing immunogenic cell death (ICD) in tumor cells, it triggers a strong antitumor immune response and inhibits the proliferation and metastasis of TNBC.

NIR-II photothermal therapy combined with activatable immunotherapy against the recurrence and metastasis of orthotopic triple-negative breast cancer

It remains a clinical challenge to treat triple-negative breast cancer due to its aggressiveness and metastasis. Photothermal therapy (PTT) in combination with checkpoint blockade immunotherapy offers a promising strategy for such intractable tumors. In this study, a second near-infrared (NIR-II) photothermal agent (PCD NPs) and a tumor microenvironment-activatable nanoprodrug (NLG NPs) for indoleamine 2,3-dioxygenase 1 (IDO-1) blockade have been designed for the therapy of orthotopic triple-negative breast cancer. The NIR-II absorption of PCD NPs can guarantee the high penetration depth of the laser during PTT. At the same time, NLG NPs can be decomposed into the NLG919 monomer in the tumor microenvironment, which can effectively strengthen the immunogenic cell death-induced immune response. NIR-II PTT in synergy with IDO-1 blockade can effectively inhibit tumor growth and prevent tumor recurrence and metastasis. This work thus provides a safe, efficient and feasible method for the treatment of malignant tumors.

Boosting Nonradiative Decay of Boron Difluoride Formazanate Dendrimers for NIR-II Photothermal Theranostics

The development of small molecular dyes excitable in the second near-infrared window (NIR-II, 1000-1700 nm) is crucial for deep-tissue penetration and maximum permissible exposure in cancer photothermal theranostics. Herein, we employed a dendrimer engineering strategy to develop the boron difluoride formazanate (BDF) dye BDF-8OMe for photoacoustic imaging-mediated NIR-II photothermal therapy. BDF-8OMe, characterized by an increased molecular branching degree and extended π-conjugation, exhibited broad absorbance peaked at 905 nm, with the absorption tail extending to 1300 nm. Additionally, reorganization energy calculation, molecular dynamics simulation, and femtosecond transient absorption spectroscopy demonstrated that the multiple identical dendritic units of BDF-8OMe significantly enhanced the molecular motions, enabling the nanoparticles (NPs) to rapidly release 94.4% of the excited state energy through nonradiative decay at a rate of 11.7 ps. Under 1064 nm photoirradiation, BDF-8OMe NPs achieved a high photothermal conversion efficiency of 62.5%, facilitating NIR-II photothermal theranostics. This work highlights the potential of the dendrimer-building strategy in developing NIR-II excitable small molecular dyes for efficient photothermal theranostics.

From X- To J-Aggregation: Subtly Managing Intermolecular Interactions for Superior Phototheranostics with Precise 1064 nm Excitation

The stacking mode in aggregate state results from a delicate balance of supramolecular interactions, which closely affects the optoelectronic properties of organic π-conjugated systems. Then, managing these interactions is crucial for advancing phototheranostics, yet remains challenging. A subtle strategy involving peripheral phenyl groups is debuted herein to transform X-aggregated SQ-H into J-aggregated SQ-Ph, reorienting intermolecular dipole interactions while rationally modulating π-π interactions. Co-assembled with liposomes (DSPE-PEG2000), SQ-Ph nanoparticles (NPs) exhibit low toxicity, superior biocompatibility, and a bathochromic shift to the 1064 nm match-excited NIR-II region, with a fluorescence brightness (ε1064 nm ΦNIR-II) of 4129 M-1 cm-1 and a photothermal conversion efficiency (PCE) of 48.3%. Preliminary in vivo experiments demonstrate that SQ-Ph NPs achieve a signal-to-background ratio (SBR) of up to 14.29 in NIR-II fluorescence imaging (FLI), enabling highly efficient photothermal therapy (PTT) of tumors guided by combined photoacoustic imaging (PAI). This study not only enriches the J-aggregation library but also provides a paradigm for optimizing photosensitizers at the supramolecular level.

NIR-II absorption and photothermal conversion in a photochromic metal-organic framework based on cis-2,2'-biquinoline-4,4'-dicarboxylate

A BCA cis-coordinated MOF (1) was initially discovered to exhibit electron transfer photochromism. Remarkably, the photogenerated radicals (1P) showed a maximum absorption enhancement peak at 1158 nm, resulting from the synergistic effects of planar π-conjugation induced by cis-coordination and π-π interactions among [BCA]˙˙ radicals, thereby promoting the NIR-II photothermal effect.

Configuration-Mediated Efficient Non-Radiative Transition for R848-Assisted Photothermal Immunotherapy to Inhibit Tumor Growth and Metastasis by An In Situ Tumor Vaccine Strategy

Cancer metastasis remains a critical factor contributing to the current limitations in cancer treatment. Photothermal immunotherapy has emerged as a safe and potent therapeutic approach, demonstrating the capability to suppress tumor growth and metastasis. While researchers have extensively investigated various structural modifications to enhance photothermal conversion performance, the influence of molecular configuration has received comparatively limited attention. In this study, we synthesized two isomers, CZTBT and LVTBT, which possessed distinct configurations. LVTBT, characterized by a flatter molecular configuration, exhibited an extended absorption wavelength and a higher molar extinction coefficient. Its excited state facilitated stronger rotation for non-radiative transitions, leading to a high photothermal conversion efficiency (PCE) of 36.3 %. When combined with R848, LVTBT@R848 nanoparticles (NPs)-mediated photothermal immunotherapy functioned as an in situ tumor vaccine, promoting the maturation of dendritic cells (DCs), T cell infiltration, and the differentiation of natural killer (NK) cells and memory T cells, thereby activating the strong immune response. Consequently, it significantly inhibited the growth of both primary and distant tumors, while also limiting lung metastasis. In summary, this study proposed a configuration-mediated non-radiative transition strategy for efficient photothermal immunotherapy, advancing the frontiers of organic photothermal agents (OPTAs) design and synthesis.

Recent Advances in Strategies to Enhance Photodynamic and Photothermal Therapy Performance of Single-Component Organic Phototherapeutic Agents

Photodynamic therapy (PDT) and photothermal therapy (PTT) have emerged as promising treatment options, showcasing immense potential in addressing both oncologic and nononcologic diseases. Single-component organic phototherapeutic agents (SCOPAs) offer advantages compared to inorganic or multicomponent nanomedicine, including better biosafety, lower toxicity, simpler synthesis, and enhanced reproducibility. Nonetheless, how to further improve the therapeutic effectiveness of SCOPAs remains a challenging research area. This review delves deeply into strategies to improve the performance of PDT or PTT by optimizing the structural design of SCOPAs. These strategies encompass augmenting reactive oxygen species (ROS) generation, mitigating oxygen dependence, elevating light absorption capacity, broadening the absorption region, and enhancing the photothermal conversion efficiency (PCE). Additionally, this review also underscores the ideal strategies for developing SCOPAs with balanced PDT and PTT. Furthermore, the potential synergies are highlighted between PDT and PTT with other treatment modalities such as ferroptosis, gas therapy, chemotherapy, and immunotherapy. By providing a comprehensive analysis of these strategies, this review aspires to serve as a valuable resource for clinicians and researchers, facilitating the wider application and advancement of SCOPAs-mediated PDT and PTT.

A tactfully designed photothermal agent collaborating with ascorbic acid for boosting maxillofacial wound healing

Maxillofacial injuries that may cause severe functional and aesthetic damage require effective and immediate management due to continuous exposure to diverse microbial populations. Moreover, drug resistance, biofilm formation, and oxidative stress significantly impede timely bacterial removal and immune function, making the exploration of advanced materials for maxillofacial wound healing an appealing yet highly challenging task. Herein, a near-infrared photothermal sterilization agent was designed, encapsulated with liposomes and coated with ascorbic acid known for its antioxidant and immune-regulatory functions. The resulting nanoparticles, 4TPE-C6T-TD@AA, effectively neutralize reactive oxygen species generated by lipopolysaccharides, facilitate the conversion of pro-inflammatory M1 macrophages to anti-inflammatory M2 macrophages, and eliminate >90% of Staphylococcus aureus and Escherichia coli by disrupting bacterial physiological functions upon exposure to 808 nm laser irradiation. In vivo experiments demonstrate that 4TPE-C6T-TD@AA rapidly eliminates bacteria from infected wounds in the maxillofacial region of rats, and significantly promotes healing in S. aureus-infected wounds by enhancing collagen formation and modulating the inflammatory microenvironment. In conclusion, this study presents a promising therapeutic strategy for effectively combating bacterial infections and excessive inflammation in treating maxillofacial injuries.

NIR-II-activated whole-cell vaccine with ultra-efficient semiconducting diradical oligomers for breast carcinoma growth and metastasis inhibition

High-performance phototheranostics with combined photothermal therapy and photoacoustic imaging have been considered promising approaches for efficient cancer diagnosis and treatment. However, developing phototheranostic materials with efficient photothermal conversion efficiency (PCE), especially over the second near-infrared window (NIR-II, 1000-1700 nm), remains challenging. Herein, we report an ultraefficient NIR-II-activated nanomedicine with phototheranostic and vaccination capability for highly efficient in vivo tumor elimination and metastasis inhibition. The NIR-II nanomedicine of a semiconducting biradical oligomer with a motor-flexible design was demonstrated with a record-breaking PCE of 87% upon NIR-II excitation. This nanomedicine inherently features extraordinary photothermal stability, good biocompatibility, and excellent photoacoustic performance, contributing to high-contrast photoacoustic imaging in living mice and high-performance photothermal elimination of tumors. Moreover, a whole-cell vaccine based on a NIR-II nanomedicine with NIR-II-activated performance was further designed to remotely activate the antitumor immunologic memory and effectively inhibit tumor occurrence and metastasis in vivo, with good biosafety. Thus, this work paves a new avenue for designing NIR-II active semiconducting biradical materials as a promising theranostics platform and further promotes the development of NIR-II nanomedicine for personalized cancer treatment.

Donor-Acceptor Functionalized Water-Soluble Metal-Organic Cages Showing an Excellent Synergistic Photothermal-Chemotherapy Effect

Water-soluble metal-organic cages (WSMOCs) show high potential as antitumor agents, while the targeted functionalization of WSMOCs toward enhanced antitumor performances is a challenging task. Herein, WSMOCs were functionalized with donor-acceptor (D-A) systems for synergistic photothermal-chemotherapy. Octahedral [M6L4] cages based on a 2,4,6-tri(2-pyridine-4-yl)-1,3,5-triazine (TPT) acceptor and M(bpy)2+ (M = Pd for 1a, Pt for 1b) nodes were functionalized with tetrathiafulvalene (TTF) to form TTF@1a and TTF@1b. This D-A functionalization enhanced charge transfer, extending absorption into the near-infrared region with photothermal conversion efficiencies of 35.65% for TTF@1a and 40.65% for TTF@1b. Also, the D-A functionalization was found to enhance the stability of the compound and induce their aggregation into nanoparticles to increase their cellular compatibility. Additionally, the acidic-sensitive ion release feature of the compounds made them promising for targeted chemotherapy. In vitro and in vivo tests demonstrated the effectiveness of this synergistic approach for antitumor applications.

Finely Tailored Conjugated Small Molecular Nanoparticles for Near-Infrared Biomedical Applications

Near-infrared (NIR) phototheranostics (PTs) show higher tissue penetration depth, signal-to-noise ratio, and better biosafety than PTs in the ultraviolet and visible regions. However, their further advancement is severely hindered by poor performances and short-wavelength absorptions/emissions of PT agents. Among reported PT agents, conjugated small molecular nanoparticles (CSMNs) prepared from D-A-typed photoactive conjugated small molecules (CSMs) have greatly mediated this deadlock by their high photostability, distinct chemical structure, tunable absorption, intrinsic multifunctionality, and favorable biocompatibility, which endows CSMNs with more possibilities in biological applications. This review aims to introduce the recent progress of CSMNs for NIR imaging, therapy, and synergistic PTs with a comprehensive summary of their molecular structures, structure types, and optical properties. Moreover, the working principles of CSMNs are illustrated from photophysical and photochemical mechanisms and light-tissue interactions. In addition, molecular engineering and nanomodulation approaches of CSMs are discussed, with an emphasis on strategies for improving performances and extending absorption and emission wavelengths to the NIR range. Furthermore, the in vivo investigation of CSMNs is illustrated with solid examples from imaging in different scenarios, therapy in 2 modes, and synergistic PTs in combinational functionalities. This review concludes with a brief conclusion, current challenges, and future outlook of CSMNs.

A Near-Infrared II Luminogen with a Photothermal Effect toward Tumor Drug Resistance Reversal

Multidrug resistance of tumor cells has greatly limited the chemotherapy effect. The development of reliable strategies to deal with tumor multidrug resistance is highly desirable for tumor therapy. In this work, a near-infrared II (NIR II) luminogen was rationally designed and prepared, which could act as a photothermal reagent to reverse the drug resistance of tumor cells by reducing the related protein expression, achieving a high inhibition efficiency with the synergistic effect of chemotherapeutic drugs. By the selection of a strong electron-withdrawing unit, the emission peak of the luminogen could reach 973 nm. Moreover, this luminogen shows outstanding photothermal conversion ability and improved thermal stability compared to ICG. Notably, after the photothermal treatment of drug-resistant tumor cells by the NIR II luminogen, the antitumor efficiency of chemotherapeutic drugs, including paclitaxel, cis-platinum, and doxorubicin, was significantly enhanced. The mechanism exploration revealed that drug resistance-related proteins were remarkably reduced, making the cells more sensitive toward drugs. Thus, this strategy demonstrated a promising and reliable approach to reverse the drug resistance of tumor cells for efficient tumor inhibition in the clinic.

Synergistic effects of Au nanoparticles in SiO2@Au@Polyaniline system for improved photothermal performance

A SiO2@Au@Polyaniline (SiO2@Au@PAN) system has been successfully fabricated leveraging the synergistic effects of gold nanoparticles (AuNPs) to realize enhanced photothermal performance. The SiO2@Au@PAN exhibited strong near-infrared (NIR) absorbance, excellent photothermal conversion efficiency, good dispersibility, and outstanding photostability. The SiO2 nanospheres as the template provided numerous binding sites for coating of AuNPs. Subsequently, aniline was grafted onto SiO2 to form PAN, which further facilitated the growth of AuNPs. The high efficiency of electron transfer from PAN to AuNPs was utilized to enhance the photothermal performance, resulting in a photothermal conversion efficiency of 41.47%. Additionally, the effects of SiO2 with different sizes on the anchoring of AuNPs and the impact of aniline with varying concentrations on the morphology and photothermal properties of the materials were investigated. Finally, we verified the photothermal therapeutic (PTT) effect of SiO2@Au@PAN at cellular level, with results demonstrating effective destruction of cancer cells. This work may provide an approach for establishing a multi-component PTT platform based on the synergistic effects of AuNPs, holding significant potential for biomedical and biochemistry applications.

Integrating Molecular Motions in Ternary Cocrystals for NIR-II Photothermal Conversion

Organic photothermal conversion materials hold immense promise for various applications owing to their structural flexibility. Recent research has focused on enhancing near-infrared (NIR) absorption and mitigating radiative transition processes. In this study, we have developed a viable approach to the design of photothermal conversion materials through the construction of ternary organic cocrystals, by introducing a third component as a molecular blocker and motion unit into a binary donor-acceptor system. Superstructural and photophysical properties of the ternary cocrystals were characterized using various spectroscopic techniques. The role of the molecular blocker in radical stabilization and photothermal conversion was demonstrated. Intriguingly, the motions of the entire pyrene molecules in the cocrystal have been observed by the results of variable temperature single-crystal X-ray diffraction. The excellent performance of the ternary cocrystal as a photothermal material was validated through efficient NIR-II photothermal and solar-driven water evaporation experiments. The efficiency of water evaporation reached 88.7 %, with a corresponding evaporation rate of 1.29 kg m-2 h-1, representing excellent performance among pure organic small molecular photothermal conversion materials. Our research underscores the introduction of molecular blockers and motion units to stabilize radicals and produce outstanding photothermal conversion materials, offering new pathways for developing efficient and stable photothermal conversion materials.

Targeting of Low-Immunogenic Poly(ethylene glycol) Nanoparticles for Photothermal-Enhanced Immunotherapy

The assembly of low-immunogenic poly(ethylene glycol) nanoparticles (PEG NPs) for targeted delivery of therapeutics (i.e., mitoxantrone and imidazoquinoline) and improved photothermal-immunotherapy is reported. The targeted PEG NPs incorporating targeting molecules of hyaluronic acid are engineered via the templating of metal-organic frameworks, which can circumvent accelerated blood clearance and exhibit prolonged circulation time as well as improved accumulation of therapeutics at tumor sites. The targeted delivery of mitoxantrone under laser radiation induces immunogenic cell death of tumor cells, which is combined with toll-like receptor 7/8 agonists of imidazoquinoline to trigger immune responses of cytotoxic T lymphocytes for the eradication of tumor cells. Furthermore, the treatment can induce tumor-specific immune responses that inhibit metastatic lung tumor growth. This reported targeted PEG NPs provide a rational design for cancer immunotherapy.

Biomimetic Metallacage Nanoparticles with Aggregation-Induced Emission for NIR-II Fluorescence Imaging-Guided Synergistic Immuno-Phototherapy of Tumors

The integration of theranostics, which combines diagnostics with therapeutics, has markedly improved the early detection of diseases, precise medication management, and assessment of treatment outcomes. In the realm of oncology, organoplatinum-based supramolecular coordination complexes (SCCs) that can coload therapeutic agents and imaging molecules have emerged as promising candidates for multimodal theranostics of tumors. To address the challenges of tumor-targeted delivery and multimodal theranostics for SCCs, this study employs a cell membrane cloaking strategy to fabricate biomimetic metallacage nanoparticles (MCNPs) with multimodal imaging capabilities and homologous targeting capabilities. Specifically, a photosensitizer molecule (BTTP) containing AIE-active groups was assembled into a metallacage of C-BTTP through Pt-N coordination. This process endows the metallacage with strong NIR-II fluorescence in the aggregated state and significantly superior ROS generation compared to that of the precursor ligand. After being encapsulated with F127, the MCNPs were further cloaked with U87 cancer cell membranes, creating biomimetic MCNPs that achieve tumor-targeting capabilities. Verified by in vitro and in vivo experiments, MCNPs enable multimodal imaging and initiate immunotherapy under photothermal and photodynamic stimulation, leading to synergistic antitumor effects. Furthermore, the evaluation of immunogenic cell death and dendritic cell maturation rate in U87 tumor-bearing mice confirmed the mechanism of photothermal and photodynamic synergistic immunotherapy. This study provides an innovative strategy for enhancing the tumor-targeting and therapeutic efficiency of SCCs, offering a versatile strategy for efficient and minimally invasive theranostics of tumors. The development of such biomimetic nanoparticles represents a significant advancement in the field of nanomedicine, potentially transforming cancer treatment through personalized and targeted therapies.

NIR-II AIEgens for Infectious Diseases Phototheranostics

Pathogenic infectious diseases have persistently posed significant threats to public health. Phototheranostics, which combines the functions of diagnostic imaging and therapy, presents an extremely promising solution to block the spread of pathogens as well as the outbreak of epidemics owing to its merits of a wide-spectrum of activity, high controllability, non-invasiveness, and difficult to acquire resistance. Among multifarious phototheranostic agents, second near-infrared (NIR-II, 1000-1700 nm) aggregation-induced emission luminogens (AIEgens) are notable by virtue of their deep penetration depth, excellent biocompatibility, balanced radiative and nonradiative decay and aggregation-enhanced theranostic performance, making them an ideal option for combating pathogens. This minireview provides a systematical summary of the latest advancements in NIR-II AIEgens with emphasis on the molecular design and nanoplatform formulation to fulfill high-efficiency in treating bacterial and viral pathogens, classified by disease models. Then, the current challenges, potential opportunities, and future research directions are presented to facilitate the further progress of this emerging field.

Applications of nanotheranostics in the second near-infrared window in bioimaging and cancer treatment

Achieving accurate and efficient tumor imaging is crucial in the field of tumor treatment, as it facilitates early detection and precise localization of tumor tissues, thereby informing therapeutic strategies and surgical interventions. The optical imaging technology within the second near-infrared (NIR-II) window has garnered significant interest for its remarkable benefits, such as enhanced tissue penetration depth, superior signal-to-background ratio (SBR), minimal tissue autofluorescence, reduced photon attenuation, and lower tissue scattering. This review explained the design and optimization strategies of nano-agents responsive to the NIR-II window, such as single-walled carbon nanotubes, quantum dots, lanthanum-based nanomaterials, and noble metal nanomaterials. These nano-agents enable non-invasive, deep-tissue imaging with high spatial resolution in the NIR-II window, and their superior optical properties significantly improve the accuracy, efficiency, and versatility of imaging-guided tumor treatments. And we discussed the characteristics and advantages of fluorescence imaging (FL)/photoacoustic imaging (PA) in NIR-II window, providing a comprehensive overview of the latest research progress of different nano-agents in FL/PA imaging-guided tumor therapy. Furthermore, we exhaustively reviewed the latest applications of multifunctional nano-phototherapy technologies carried out by NIR-II light including photothermal therapy (PTT), photodynamic therapy (PDT), and combined modalities like photothermal-chemodynamic therapy (PTT-CDT), photothermal-chemotherapy (PTT-CT), and photothermal- immunotherapy (PTT-IO). These imaging-guided integrated tumor therapy approaches within the NIR-II window have gradually matured over the past decade and are expected to become a safe and effective non-invasive tumor treatment. Finally, we outlined the prospects and challenges of development and innovation of the NIR-II integrated diagnosis and therapy nanoplatform. This review aims to provide insightful perspectives for future advancements in NIR-II optical tumor diagnosis and integrated treatment platforms.

Orbicular-Donor-Acceptor System in N-doped Nanographene for Highly Efficient NIR-II Photothermal Therapy

Developing stable and efficient photothermal agents (PTAs) for the second near-infrared window (NIR-II, 1 000-1700 nm) photothermal therapy (PTT) is highly desirable but remains challenging. Herein, a facile strategy to prepare NIR-II nano-PTA based on the ionic N-doped nanographene hexapyrrolohexaazacoronene (HPHAC) is reported featuring a specific orbicular-donor-acceptor (O-D-A) structure. Oxidizing HPHAC 1 to dication 12+ causes a substantial decrease in its band gap, leading to a shift in absorption from the confined UV region to a broad absorption range that reaches up to 1400 nm. The dication 12+ exhibits global aromaticity and excellent stability. Theoretical investigation demonstrates that the strong NIR-II absorption of 12+ is attributed to a distinct inner-to-outer intramolecular charge transfer. Encapsulating 12+ with amphiphilic polymers results in water-soluble 12+ NPs with retained optical characteristics. The 12+ NPs exhibit exceptional biocompatibility, intense photoacoustic responses, and a high photothermal conversion efficiency of 72% under the 1064 nm laser irradiation, enabling efficient PTT of cancer cells. The "O-D-A" system on HPHAC, which is created by a simple redox approach, provides a novel strategy to construct efficient NIR-II photothermal materials through molecular engineering of nanographenes.

Enhancing Near-Infrared Photothermal Performance by Molecular Aggregation Optimization in Semiconductive Coordination Polymers

Near-infrared (NIR) photothermal conversion materials have recently received widespread attention due to their potential in diverse applications. However, highly efficient organic-based NIR photothermal agents remain limited. Developing strategies to enhance the efficiency of NIR photothermal materials and elucidating the relationship between the NIR photothermal performance and molecular aggregation are highly desired. Herein, we report two coordination polymers {[Cd2(ONDI)(ox)]·2/3(H2O)}n (1) and [Ba(ONDI)(H2O)2]n (2), in which the ONDI2- ligands assemble into different π-π stacking arrangements. Compound 1 exhibits H-aggregation, while compound 2 displays X-aggregation. The X-aggregation in compound 2 extends the optical absorption into the NIR region and enhances the absorption intensity. Consequently, compound 2 demonstrates a 1.8-fold increase in NIR photothermal efficiency (68.6%) compared to compound 1 (38.8%), attributed to more effective π-π interactions in X-aggregation. In addition, both compounds show semiconductive properties, with conductivities of 2.1 × 10-7 S/cm for compound 1 and 3.0 × 10-7 S/cm for compound 2 at 30 °C in a nitrogen atmosphere. These properties arise from the synergistic effects of "band-like" charge transport within crystals and "hopping" charge transport across grain boundaries. By integration of their NIR photothermal effects and semiconductive properties, compounds 1 and 2 show interesting NIR photoelectrical responses.

De novo strategy of organic semiconducting polymer brushes for NIR-II light-triggered carbon monoxide release to boost deep-tissue cancer phototheranostics

The integration of photoacoustic imaging (PAI) and photothermal therapy (PTT) within the second near-infrared (NIR-II) window, offering a combination of high-resolution imaging and precise non-invasive thermal ablation, presents an attractive opportunity for cancer treatment. Despite the significant promise, the development of this noninvasive phototheranostic nanomedicines encounters challenges that stem from tumor thermotolerance and limited therapeutic efficacy. In this contribution, we designed an amphiphilic semiconducting polymer brush (SPB) featuring a thermosensitive carbon monoxide (CO) donor (TDF-CO) for NIR-II PAI-assisted gas-augmented deep-tissue tumor PTT. TDF-CO nanoparticles (NPs) exhibited a powerful photothermal conversion efficiency (43.1%) and the capacity to trigger CO release after NIR-II photoirradiation. Notably, the liberated CO not only acts on mitochondria, leading to mitochondrial dysfunction and promoting cellular apoptosis but also hinders the overexpression of heat shock proteins (HSPs), enhancing the tumor's thermosensitivity to PTT. This dual action accelerates cellular thermal ablation, achieving a gas-augmented synergistic therapeutic effect in cancer treatment. Intravenous administration of TDF-CO NPs in 4T1 tumor-bearing mice demonstrated bright PAI signals and remarkable tumor ablation under 1064 nm laser irradiation, underscoring the potential of CO-mediated photothermal/gas synergistic therapy. We envision this tailor-made multifunctional NIR-II light-triggered SPB provides a feasible approach to amplify the performance of PTT for advancing future cancer phototheranostics.

A NIR-II Organic Dendrimer with Superb Photothermal Performance Based on Electron-Donor Iteration for Photothermal Immunotherapy

Organic photothermal materials have attracted extensive attention due to their designable molecular structure, tunable excited-state properties, and excellent biocompatibility, however, the development of near-infrared II (NIR-II) absorbing organic photothermal materials with high photothermal conversion efficiency (PTCE) and molar extinction coefficient (ɛ) remains challenging. Herein, a novel "electron-donor iteration" strategy is proposed to construct organic photothermal dendrimers (CR-DPA-T, CR-(DPA)2-T and CR-(DPA)3-T) with donor-π-acceptor-π-donor (D-π-A-π-D) features and diradical characteristics. Owing to the enhanced D-A effect and intramolecular motions, their absorption and photothermal capacity increase as the generation grows. Surprisingly, an excellent photothermal performance (ɛ1064 × PTCE1064) with a superb value of 2.85 × 104 in the NIR-II region is achieved for CR-(DPA)3-T nanoparticles (CR-(DPA)3-T NPs) compared to most reported counterparts. Besides, CR-(DPA)3-T NPs exhibit superior antitumor efficacy by the synergistic effect of photothermal therapy (PTT) and immunotherapy, efficiently inhibiting the growth of both primary and distant tumors. To the best knowledge, organic photothermal dendrimer is for the first time reported, and a universal donor engineering strategy is offered to develop NIR-II-absorbing organic photothermal materials for photothermal immunotherapy.

Temperature-responsive two-dimensional polydopamine hydrogel: Preparation, mechanisms, and applications in cancer treatment

Temperature-responsive hydrogels are advanced materials that exhibit significant physical or chemical changes in response to temperature variations. When the temperature reaches a specific threshold, these hydrogels alter their properties accordingly. They offer significant advantages in cancer therapy, including precise control over drug release, minimized toxicity, improved therapeutic efficacy, and biodegradability. Advancing the development of novel temperature-responsive hydrogels is crucial for enhancing therapeutic strategies. Herein, two-dimensional polydopamine (2D PDA) was first combined with chitosan (CTS) to create a temperature-responsive hydrogel for the control and release of anticancer drugs. Leveraging the carbonyl-rich nature of 2D PDA, we initiated a reversible cyclization reaction between CTS and the carbonyl groups on the surface of 2D PDA, resulting in a temperature-responsive CTS@2D PDA (CP) hydrogel. Furthermore, the CP hydrogel template was incorporated with the photosensitizer zinc phthalocyanine (ZnPc) and sodium percarbonate (SPC), an oxygen (O2) donor, to form a composite hydrogel (CSZP hydrogel). O2 released from the CSZP hydrogel mitigated solid tumor hypoxia and suppressed the expression of hypoxia-inducible factor-1α (HIF-1α), thereby augmenting the efficacy of photodynamic therapy (PDT). This temperature-responsive hydrogel represented a highly promising platform for the precise and controlled release of various therapeutics, thereby advancing the field of targeted disease treatment.

Titanium boride nanosheets with photo-enhanced sonodynamic efficiency for glioblastoma treatment

Sonodynamic therapy (SDT) has garnered significant attention in cancer treatment, however, the low-yield reactive oxygen species (ROS) generation from sonosensitizers remains a major challenge. In this study, titanium boride nanosheets (TiB2 NSs) with photo-enhanced sonodynamic efficiency was fabricated for SDT of glioblastoma (GBM). Compared with commonly-used TiO2 nanoparticles, the obtained TiB2 NSs exhibited much higher ROS generation efficiency under ultrasound (US) irradiation due to their narrower band gap (2.50 eV). Importantly, TiB2 NSs displayed strong localized surface plasmon resonance (LSPR) effect in the second near-infrared (NIR II) window, which facilitated charge transfer rate and improved the separation efficiency of US-triggered electron-hole pairs, leading to photo-enhanced ROS generation efficiency. Furthermore, TiB2 NSs were encapsulated with macrophage cell membranes (CM) and then modified with RGD peptide to construct biomimetic nanoagents (TiB2@CM-RGD) for efficient blood-brain barrier (BBB) penetrating and GBM targeting. After intravenous injection into the tumor-bearing mouse, TiB2@CM-RGD can efficiently cross BBB and accumulate in the tumor sites. The tumor growth was significantly inhibited under simultaneous NIR II laser and US irradiation without causing appreciable long-term toxicity. Our work highlighted a new type of multifunctional titanium-based sonosensitizer with photo-enhanced sonodynamic efficiency for GBM treatment. STATEMENT OF SIGNIFICANCE: Titanium boride nanosheets (TiB2 NSs) with photo-enhanced sonodynamic efficiency was fabricated for SDT of glioblastoma (GBM). The obtained TiB2 NSs displayed strong localized surface plasmon resonance (LSPR) effect in the second near-infrared (NIR II) window, which facilitated charge transfer rate and improved the separation efficiency of US-triggered electron-hole pairs, leading to photo-enhanced ROS generation efficiency. Furthermore, TiB2 NSs were encapsulated with macrophage cell membranes (CM) and then modified with RGD peptide to construct biomimetic nanoagents (TiB2@CM-RGD) for efficient blood-brain barrier (BBB) penetrating and GBM targeting. After intravenous injection into the tumor-bearing mouse, TiB2@CM-RGD can efficiently cross BBB and accumulate in the tumor sites. The tumor growth was significantly inhibited under simultaneous NIR II laser and US irradiation without causing appreciable long-term toxicity.

Supramolecular H-Aggregates of Squaraines with Enhanced Type I Photosensitization for Combined Photodynamic and Photothermal Therapy

Combined photodynamic and photothermal therapy (PDT and PTT) can achieve more superior therapeutic effects than the sole mode by maximizing the photon utilization, but there remains a significant challenge in the development of related single-molecule photosensitizers (PSs), particularly those with type I photosensitization. In this study, self-assembly of squaraine dyes (SQs) is shown to be a promising strategy for designing PSs for combined type I PDT and PTT, and a supramolecular PS (TPE-SQ7) has been successfully developed through subtle molecular design of an indolenine SQ, which can self-assemble into highly ordered H-aggregates in aqueous solution as well as nanoparticles (NPs). In contrast to the typical quenching effect of H-aggregates on reactive oxygen species (ROS) generation, our results encouragingly manifest that H-aggregates can enhance type I ROS (•OH) generation by facilitating the intersystem crossing process while maintaining a high PTT performance. Consequently, TPE-SQ7 NPs with ordered H-aggregates not only exhibit superior combined therapeutic efficacy than the well-known PS (Ce6) under both normoxic and hypoxic conditions but also have excellent biosafety, making them have important application prospects in tumor phototherapy and antibacterial fields. This study not only proves that the supramolecular self-assembly of SQs is an effective strategy toward high-performance PSs for combined type I PDT and PTT but also provides a different understanding of the effect of H-aggregates on the PDT performance.

Near-Infrared II Agent with Excellent Overall Performance for Imaging-Guided Photothermal Thrombolysis

Near-infrared II (NIR-II) imaging and photothermal therapy hold tremendous potential in precision diagnosis and treatment within biological organisms. However, a significant challenge is the shortage of NIR-II fluorescent probes with both high photothermal conversion coefficient (PCE) and fluorescence quantum yield (ΦF). Herein, we address this issue by integrating a large conjugated electron-withdrawing core, multiple rotors, and multiple alkyl chains into a molecule to successfully generate a NIR-II agent 4THTPB with excellent PCE (87.6%) and high ΦF (3.2%). 4THTPB shows a maximum emission peak at 1058 nm, and the emission tail could extend to as long as 1700 nm. These characteristics make its nanoparticles (NPs) perform well in NIR-II high-resolution angiography, thereby allowing for precise diagnosis of thrombus through NIR-II imaging and enabling efficient photothermal thrombolysis. This work not only furnishes a NIR-II agent with excellent overall performance but also provides valuable guidance for the design of high-performance NIR-II agents.

Multifunctional Adaptable Injectable TiN-Based Hydrogels for Antitumor and Antidrug-Resistant Bacterial Therapy

The close relationship between bacteria and tumors has recently attracted increasing attention, and an increasing number of resources are being invested in the research and development of biomedical materials designed for the treatment of both. In this study, prefabricated TiN nanodots (NDs) and Fe(CO)5 nanoparticles are combined into sodium alginate (ALG) hydrogels to create a biomedical material for the topical treatment of breast cancer and subcutaneous abscesses, and a pseudocatalytic hydrogel with intrinsic photothermal and antibacterial activities is synthesized. TiN+Fe(CO)5+ALG hydrogels are used to determine the ability of Fe(CO)5 to promote CO production. Moreover, TiN NDs catalyze the production of reactive oxygen species (ROS) from hydrogen peroxide in tumor microenvironments and exhibit excellent photothermal conversion properties. After local injection of the TiN+Fe(CO)5+ALG hydrogel into subcutaneous tumors and subcutaneous abscesses, and two-zone near-infrared (NIR-II) irradiation, tumor cells and methicillin-resistant Staphylococcus aureus are effectively removed by the hydrogel, the mouse epidermis exhibiting complete recovery within 8 d, indicating that this hydrogel exhibits better antibacterial efficacy than the small-molecule antibiotic penicillin. This study demonstrates the potential of novel hydrogels for antitumor and antimicrobial combination therapy and aims to provide design ideas for the research and development of multifunctional antitumor and antimicrobial drug combinations.

The Quest for Two-Dimensional MBenes: From Structural Evolution to Solar-Driven Hybrid Systems for Water-Fuel-Energy Generation and Phototherapy

The field of 2D materials has advanced significantly with the emergence of MBenes, a new material derived from the MAX phases family, a novel class of materials that originates from the MAX phases family. Herein, this article explores the unique characteristics and morphological variations of MBenes, offering a comprehensive overview of their structural evolution. First, the discussion explores the evolutionary period of 2D MBenes associated with the several techniques for synthesizing, modifying, and characterizing MBenes to tailor their structure and enhance their functionality. The focus then shifts to the defect chemistry of MBenes, electronic, catalytic, and photothermal properties which play a crucial role in designing multifunctional solar-driven hybrid systems. Second, the recent advancements and potentials of 2D MBenes in solar-driven hybrid systems e.g. photo-electro catalysis, hybrid solar evaporators for freshwater and thermoelectric generators, and phototherapy, emphasizing their crucial significance in tackling energy and environmental issues, are explored. The study further explores the fundamental principles that regulate the improved photocatalytic and photothermal characteristics of MBenes, highlighting their promise for effective utilization of solar energy and remediation of the environment. The study also thoroughly assesses MBenes' scalability, stability, and cost effectiveness in solar-driven systems. Current insights and future directions allow researchers to utilize MBenes for sustainable and varied applications. This review regarding MBenes will be valuable to early researchers intrigued with synthesizing and utilizing 2D materials for solar-powered water-energy-fuel and phototherapy systems.

Theranostic Nanoplatform Based on Polydopamine-Coated Magnetic Mesoporous Silicon for Precise Cancer Triplex Nanotherapy and Multimodal Imaging

Although targeted therapy has revolutionized oncotherapy, engineering a versatile oncotherapy nanoplatform integrating both diagnostics and therapeutics has always been an intractable challenge to overcome the limitations of monotherapy. Herein, a theranostics platform based on DI/MP-MB has successfully realized the fluorescence detection of disease marker miR-21 and the gene/photothermal/chemo triple synergetic cancer therapy, which can trace the tumor through photothermal and fluorescence dual-mode imaging and overcome the limitations of monotherapy to improve the treatment efficiency of tumors. DI/MP-MB was prepared by magnetic mesoporous silicon nanoparticles (M-MSNs) loaded with doxorubicin (Dox) and new indocyanine green (IR820), and subsequently coating polydopamine as a "gatekeeper", followed by the surface adsorbed with molecular beacons capable of targeting miR-21 for responsive imaging. Under the action of enhanced permeability retention and external magnetic field, DI/MP-MB were targeted and selectively accumulated in the tumor. MiR-21 MB hybridized with miR-21 to form a double strand, which led to the desorption of miR-21 MB from the polydopamine surface and the fluorescence recovery to realize gene silencing and fluorescence imaging for tracking the treatment process. Meanwhile, with the response to the near-infrared irradiation and the tumor's microacid environment, the outer layer polydopamine will decompose, releasing Dox and IR820 to realize chemotherapy and photothermal therapy. Finally, the ability of DI/MP-MB to efficiently suppress tumor growth was comprehensively assessed and validated both in vitro and in vivo. Noteworthily, the excellent anticancer efficiency by the synergistic effect of gene/photothermal/chemo triple therapy of DI/MP-MB makes it an ideal nanoplatform for tumor therapy and imaging.

BF2-Bridged Azafulvene Dimer-Based 1064 nm Laser-Driven Superior Photothermal Agent for Deep-Seated Tumor Therapy

Small organic photothermal agents (PTAs) with absorption bands located in the second near-infrared (NIR-II, 1000-1700 nm) window are highly desirable for effectively combating deep-seated tumors. However, the rarely reported NIR-II absorbing PTAs still suffer from a low molar extinction coefficient (MEC, ϵ), inadequate chemostability and photostability, as well as the high light power density required during the therapeutic process. Herein, we developed a series of boron difluoride bridged azafulvene dimer acceptor-integrated small organic PTAs. The B-N coordination bonds in the π-conjugated azafulvene dimer backbone endow it the strong electron-withdrawing ability, facilitating the vigorous donor-acceptor-donor (D-A-D) structure PTAs with NIR-II absorption. Notably, the PTA namely OTTBF shows high MEC (7.21×104 M-1 cm-1), ultrahigh chemo- and photo-stability. After encapsulated into water-dispersible nanoparticles, OTTBF NPs can achieve remarkable photothermal conversion effect under 1064 nm irradiation with a light density as low as 0.7 W cm-2, which is the lowest reported NIR-II light power used in PTT process as we know. Furthermore, OTTBF NPs have been successfully applied for in vitro and in vivo deep-seated cancer treatments under 1064 nm laser. This study provides an insight into the future exploration of versatile D-A-D structured NIR-II absorption organic PTAs for biomedical applications.

NIR-Absorbing Tetraphenylethene-Containing bisBODIPY Nanoplatforms Demonstrate Effective Lysosome-Targeting and Combinational Phototherapy

Photosensitizer-based phototherapies, including photodynamic therapy (PDT) and photothermal therapy (PTT), offer safe treatment modalities for tumor ablation with spatiotemporal precision. After photons are absorbed, PDT creates localized chemical damage by generating reactive oxygen species (ROS), while PTT induces localized thermal damage. However, PDT still faces hypoxic tumor challenges, while PTT encounters issues related to heat resistance and potential overheating. The combination of PDT and PTT shows great potential as an effective anticancer strategy. By targeting lysosomes with carefully designed phototherapeutic reagents for combined phototherapy, rapid dysfunction and cell death in cancer cells can be induced, showing promise for cancer treatment. Herein, two α-α-linked bisBODIPYs with tetraphenylethene (TPE) moieties are designed and synthesized. These TPE-substituted bisBODIPYs expand the absorption into NIR range (λmaxabs/λmaxem ∼ 740/810 nm) and confer aggregation-induced emission (AIE) activity (λmaxem ∼ 912 nm). Moreover, these bisBODIPYs self-assemble with surfactant F-127 into nanoparticles (NPs), which efficiently generate ROS (1O2 and •OH) in both solution and cellular environments and demonstrate superior photothermal conversion efficiencies (η ∼ 68.3%) along with exceptional photothermal stability. More importantly, these NPs showed lysosomal targeting and remarkable tumor ablation in cellular and murine models, indicating their potential in precision tumor therapy.

Croconaine-based NIR-II fluorescence imaging-guided tumor photothermal therapy induces long-term antitumor immune memory

Photothermal therapy (PTT) for cancers guided by optical imaging has recently shown great potential for precise diagnosis and efficient therapy. The second near-infrared window (NIR-II, 1000-1700 nm) fluorescence imaging (FLI) is highly desirable owing to its good spatial and temporal resolution, deep tissue penetration, and negligible tissue toxicity. Organic small molecules are attractive as imaging and treatment agents in biomedical research because of their low toxicity, fast clearance rate, diverse structures, ease of modification, and excellent biocompatibility. Various organic small molecules have been investigated for biomedical applications. However, there are few reports on the use of croconaine dyes (CRs), especially NIR-II emission CRs. To our knowledge, there have been no prior reports of NIR-II emissive small organic photothermal agents (SOPTAs) based on CRs. Herein, we report a croconaine dye (CR-TPE-T)-based nanoparticle (CR NP) with absorption and fluorescence emission in the NIR-I and NIR-II windows, respectively. The CR NPs exhibited intense NIR absorption, outstanding photothermal properties, and good biological compatibility. In vivo studies showed that CR NPs not only achieved real-time, noninvasive NIR-II FLI of tumors, but also induced significant tumor ablation with laser irradiation guided by imaging, without apparent side effects, and promoted the formation of antitumor immune memory in a colorectal cancer model. In addition, the CR NPs displayed efficient inhibition of breast tumor growth, improved longevity of mice and triggered efficient systemic immune responses, which further inhibited tumor metastasis to the lungs. Our study demonstrates the great potential of CRs as therapeutic agents in the NIR-II region for cancer diagnosis.

Mechanism of Self-Oxidative Copolymerization and its Application with Polydopamine-pyrrole Nano-copolymers

Currently, the copolymer of dopamine (DA) and pyrrole (PY) via chemical and electrochemical oxidation usually requires additional oxidants, and lacks flexibility in regulating the size and morphology, thereby limiting the broad applications of DA-PY copolymer in biomedicine. Herein, the semiquinone radicals produced by the self-oxidation of DA is ingeniously utilized as the oxidant to initiate the following copolymerization with PY, and a series of quinone-rich polydopamine-pyrrole copolymers (PDAm-nPY) with significantly enhanced absorption in near-infrared (NIR) region without any additional oxidant assistance is obtained. Moreover, the morphology and size of PDAm-nPY can be regulated by changing the concentration of DA and PY, thereby optimizing nanoscale PDA0.05-0.15PY particles (≈ 150 nm) with excellent NIR absorption and surface modification activity are successfully synthesized. Such PDA0.05-0.15PY particles show effective photoacoustic (PA) imaging and photothermal therapy (PTT) against 4T1 tumors in vivo. Furthermore, other catechol derivatives can also copolymerize with PY under the same conditions. This work by fully utilizing the semiquinone radical active intermediates produced through the self-oxidation of DA reduces the dependence on external oxidants in the synthesis of composite materials and predigests the preparation procedure, which provides a novel, simple, and green strategy for the synthesis of other newly catechol-based functional copolymers.

A Cyanine with 83.2% Photothermal Conversion Efficiency and Absorption Wavelengths over 1200 nm for Photothermal Therapy

Developing small-molecule photothermal agents (PTAs) with good near-infrared-II (NIR-II) response for deeper tissue penetration and minimizing damage to healthy tissues has attracted much attention in photothermal therapy (PTT). However, concentrating ultra-long excitation wavelengths and high photothermal conversion efficiencies (PCEs) into a single organic small molecule is still challenging due to the lack of suitable molecular structures. Here, six polymethine cyanine molecules based on the structure of indocyanine green are synthesized by increasing the conjugated structure of the two-terminal indole salts and the number of rigid methine units, and incorporating longer alkyl side chains into the indole salts. Ultimately, IC-1224 is obtained with an absorption wavelength of more than 1200 nm, which has a high PCE up to 83.2% in the NIR-II window and exhibits excellent PTT tumor ablation performance. This provides a high-performance NIR-II-responsive PTA, and offers further possibilities for the application of PTT in biomedical fields.

Tuning the photophysical properties of cyanine by barbiturate functionalization and nanoformulation for efficient optoacoustics- guided phototherapy

Cyanine derivatives are organic dyes widely used for optical imaging. However, their potential in longitudinal optoacoustic imaging and photothermal therapy remains limited due to challenges such as poor chemical stability, poor photostability, and low photothermal conversion. In this study, we present a new structural modification for cyanine dyes by introducing a strongly electron-withdrawing group (barbiturate), resulting in a new series of barbiturate-cyanine dyes (BC810, BC885, and BC1010) with suppressed fluorescence and enhanced stability. Furthermore, the introduction of BC1010 into block copolymers (PEG114-b-PCL60) induces aggregation-caused quenching, further boosting the photothermal performance. The photophysical properties of nanoparticles (BC1010-NPs) include their remarkably broad absorption range from 900 to 1200 nm for optoacoustic imaging, allowing imaging applications in NIR-I and NIR-II windows. The combined effect of these strategies, including improved photostability, enhanced nonradiative relaxation, and aggregation-caused quenching, enables the detection of optoacoustic signals with high sensitivity and effective photothermal treatment of in vivo tumor models when BC1010-NPs are administered before irradiation with a 1064 nm laser. This research introduces a barbiturate-functionalized cyanine derivative with optimal properties for efficient optoacoustics-guided theranostic applications. This new compound holds significant potential for biomedical use, facilitating advancements in optoacoustic-guided diagnostic and therapeutic approaches.

Cationic conjugated polymer coupled non-conjugated segments for dually enhanced NIR-II fluorescence and lower-temperature photothermal-gas therapy

The lack of a simple design strategy to obtain ideal conjugated polymers (CPs) with high absorbance and fluorescence (FL) in the near-infrared-II (NIR-II; 1000-1700 nm) region still hampers the success of NIR-II light-triggered phototheranostics. Herein, novel phototheranostic nanoparticles (PPN-NO NPs) were successfully prepared by coloading a cationic NIR-II CPs (PBC-co-PBF-NMe3) and a NO donor (S-nitroso-N-acetylpenicillamine, SNAP) onto a 1:1 mixture of DSPE-PEG5000 and dimyristoylphosphatidylcholine (DMPC) for NIR-II FL and NIR-II photoacoustic (PA) imaging-guided low-temperature NIR-II photothermal therapy (PTT) and gas combination therapy for cancer treatment. A precise NIR-II FL dually enhanced design tactic was proposed herein by integrating flexible nonconjugated segments (C6) into the CPs backbone and incorporating quaternary ammonium salt cationic units into the CPs side chain, which considerably increased the radiative decay pathway, resulting in desirable NIR-II FL intensity and balanced NIR-II absorption and NIR PTT properties. The phototheranostic PPN-NO NPs exhibited distinguished NIR-II FL and PA imaging performance in tumor-bearing mice models. Furthermore, the low-temperature photothermal effect of PPN-NO NPs could initiate NO release upon 980 nm laser irradiation, efficiently suppressing tumor growth owing to the combination of low-temperature NIR-II PTT and NO gas therapy in vitro and in vivo.

Peptide-IR820 Conjugate: A Promising Strategy for Efficient Vascular Disruption and Hypoxia Induction in Melanoma

Photothermal therapy (PTT) has emerged as a noninvasive and precise cancer treatment modality known for its high selectivity and lack of drug resistance. However, the clinical translation of many PTT agents is hindered by the limited biodegradability of inorganic nanoparticles and the instability of organic dyes. In this study, a peptide conjugate, IR820-Cys-Trp-Glu-Trp-Thr-Trp-Tyr (IR820-C), was designed to self-assemble into nanoparticles for both potent PTT and vascular disruption in melanoma treatment. When co-assembled with the poorly soluble vascular disrupting agent (VDA) combretastatin A4 (CA4), the resulting nanoparticles (IR820-C@CA4 NPs) accumulate efficiently in tumors, activate systemic antitumor immune responses, and effectively ablate melanoma with a single treatment and near-infrared irradiation, as confirmed by our in vivo experiments. Furthermore, by exploiting the resulting tumor hypoxia, we subsequently administered the hypoxia-activated prodrug tirapazamine (TPZ) to capitalize on the created microenvironment, thereby boosting therapeutic efficacy and antimetastatic potential. This study showcases the potential of short-peptide-based nanocarriers for the design and development of stable and efficient photothermal platforms. The multifaceted therapeutic strategy, which merges photothermal ablation with vascular disruption and hypoxia-activated chemotherapy, holds great promise for advancing the efficacy and scope of cancer treatment modalities.

Isomer engineering for deep understanding of aggregation-induced photothermal enhancement in conjugated systems

Organic photothermal materials based on conjugated structures have significant potential applications in areas such as biomedical diagnosis, therapy, and energy conversion. Improving their photothermal conversion efficiency through molecular design is critical to promote their practical applications. Especially in similar structures, understanding how the position of heteroatoms affects the conversion efficiency is highly desirable. Herein, we prepared two isomeric small D-A molecules with different sulfur atom positions (TBP-MPA and i-TBP-MPA), which display strong and broad absorption in the UV-visible region due to their strong intramolecular charge transfer characteristics. Compared to i-TBP-MPA, TBP-MPA demonstrates aggregation-induced photothermal enhancement (AIPE). Under simulated sunlight (1 kW m-2) irradiation, the stable temperature of TBP-MPA powder reached 60 °C, significantly higher than the 50 °C achieved by i-TBP-MPA. Experimental and theoretical results indicate that the S⋯N non-covalent interactions in TBP-MPA impart a more rigid conjugated framework to the molecule, inducing ordered molecular stacking during aggregation. This ordered stacking provides additional non-radiative transition channels between TBP-MPA molecules, enhancing their photothermal performance in the aggregated state. Under 1 sun irradiation, TBP-MPA achieved a water evaporation rate of 1.0 kg m-2 h-1, surpassing i-TBP-MPA's rate of 0.92 kg m-2 h-1.