A Photoinduced Nonadiabatic Decay-Guided Molecular Motor Triggers Effective Photothermal Conversion for Cancer Therapy

It remains highly challenging to identify small molecule-based photothermal agents with a high photothermal conversion efficiency (PTCE). Herein, we adopt a double bond-based molecular motor concept to develop a new class of small photothermal agents to break the current design bottleneck. As the double-bond is twisted by strong twisted intramolecular charge transfer (TICT) upon irradiation, the excited agents can deactivate non-radiatively through the conical intersection (CI) of internal conversion, which is called photoinduced nonadiabatic decay. Such agents possess a high PTCE of 90.0 %, facilitating low-temperature photothermal therapy in the presence of a heat shock protein 70 inhibitor. In addition, the behavior and mechanism of NIR laser-triggered molecular motions for generating heat through the CI pathway have been further understood through theoretical and experimental evidence, providing a design principle for highly efficient photothermal and photoacoustic agents.     

A Water‐Soluble,NIR‐Absorbing Quaterrylenediimide Chromophore for Photoacoustic Imaging and Efficient Photothermal Cancer Therapy

Precision phototheranostics, including photoacoustic imaging and photothermal therapy, requires stable photothermal agents. Developing such agents with high stability and high photothermal conversion efficiency (PTCE) remains a considerable challenge. Herein, we introduce a new photothermal agent based on water‐soluble quaterrylenediimide (QDI) that can self‐assemble into nanoparticles (QDI‐NPs) in aqueous solution. Incorporating polyethylene glycol (PEG) into the QDI core significantly enhances both physiological stability and biocompatibility of QDI‐NPs. The highly photostable QDI‐NPs offer advantages including intense absorption in the near‐infrared (NIR) and high PTCE of up to 64.7±4 %. This is higher than that of commercial indocyanine green (ICG). Their small size (ca. 10 nm) enables sustained retention in deep tumor sites and also proper clearance from the body. QDI‐NPs allow high‐resolution photoacoustic imaging and efficient 808 nm laser‐triggered photothermal therapy of cancer in vivo.     

A Water‐Soluble,NIR‐Absorbing Quaterrylenediimide Chromophore for Photoacoustic Imaging and Efficient Photothermal Cancer Therapy

Precision phototheranostics, including photoacoustic imaging and photothermal therapy, requires stable photothermal agents. Developing such agents with high stability and high photothermal conversion efficiency (PTCE) remains a considerable challenge. Herein, we introduce a new photothermal agent based on water‐soluble quaterrylenediimide (QDI) that can self‐assemble into nanoparticles (QDI‐NPs) in aqueous solution. Incorporating polyethylene glycol (PEG) into the QDI core significantly enhances both physiological stability and biocompatibility of QDI‐NPs. The highly photostable QDI‐NPs offer advantages including intense absorption in the near‐infrared (NIR) and high PTCE of up to 64.7±4 %. This is higher than that of commercial indocyanine green (ICG). Their small size (ca. 10 nm) enables sustained retention in deep tumor sites and also proper clearance from the body. QDI‐NPs allow high‐resolution photoacoustic imaging and efficient 808 nm laser‐triggered photothermal therapy of cancer in vivo.     

Antimonene Quantum Dots: Synthesis and Application as Near‐Infrared Photothermal Agents for Effective Cancer Therapy

Photothermal therapy (PTT) has shown significant potential for cancer therapy. However, developing nanomaterials (NMs)‐based photothermal agents (PTAs) with satisfactory photothermal conversion efficacy (PTCE) and biocompatibility remains a key challenge. Herein, a new generation of PTAs based on two‐dimensional (2D) antimonene quantum dots (AMQDs) was developed by a novel liquid exfoliation method. Surface modification of AMQDs with polyethylene glycol (PEG) significantly enhanced both biocompatibility and stability in physiological medium. The PEG‐coated AMQDs showed a PTCE of 45.5 %, which is higher than many other NMs‐based PTAs such as graphene, Au, MoS₂, and black phosphorus (BP). The AMQDs‐based PTAs also exhibited a unique feature of NIR‐induced rapid degradability. Through both in vitro and in vivo studies, the PEG‐coated AMQDs demonstrated notable NIR‐induced tumor ablation ability. This work is expected to expand the utility of 2D antimonene (AM) to biomedical applications through the development of an entirely novel PTA platform.     

D-A-D structured selenadiazolesbenzothiadiazole-based near-infrared dye for enhanced photoacoustic imaging and photothermal cancer therapy

Near-infrared (NIR) small molecular organic dyes as photothermal agents for cancer photothermal therapy (PTT) have attracted considerable research attention. Herein, two donor-acceptor-donor (D-A-D) structured NIR dyes, BBTT and SeBTT, are rationally designed, where the only difference is one heteroatom within the acceptor unit varying from sulfur to selenium (Se). More importantly, SeBTT NPs exhibit stronger NIR absorbance and higher photothermal conversion efficiency (PTCE ≈ 65.3%). In vivo experiments illustrate that SeBTT NPs can be utilized as a high contrast photoacoustic imaging (PAI) agent, and succeed in tumor suppression without noticeable damage to main organs under NIR photoirradiation. This study presents an effective molecular heteroatom surgery strategy to regulate the photothermal properties of NIR small molecules for enhanced PAI and PTT.     

Algae Extraction Controllable Delamination of Vanadium Carbide Nanosheets with Enhanced Near‐Infrared Photothermal Performance

The two‐dimensional (2D) vanadium carbide (V₂C) MXene has shown great potential as a photothermal agent (PTA) for photothermal therapy (PTT). However, the use of V₂C in PTT is limited by the harsh synthesis condition and low photothermal conversion efficiency (PTCE). Herein, we report a completely different green delamination method using algae extraction to intercalate and delaminate V₂AlC to produce mass V₂C nanosheets (NSs) with a high yield (90 %). The resulting V₂C NSs demonstrated good structural integrity and remarkably high absorption in near infrared (NIR) region with a PTCE as high as 48 %. Systemic in vitro and in vivo studies demonstrate that the V₂C NSs can serve as efficient PTA for photoacoustic (PA) and magnetic resonance imaging (MRI)‐guided PTT of cancer. This work provides a cost‐effective, environment‐friendly, and high‐yielding disassembly approach of MAX, opening a new avenue to develop MXenes with desirable properties for a myriad of applications.     

Coupling molecular rigidity and flexibility on fused backbones for NIR-II photothermal conversion

Great attention is being increasingly paid to photothermal conversion in the near-infrared (NIR)-II window (1000–1350 nm), where deeper tissue penetration is favored. To date, only a limited number of organic photothermal polymers and relevant theory have been exploited to direct the molecular design of polymers with highly efficient photothermal conversion, specifically in the NIR-II window. This work proposes a fused backbone structure locked via an intramolecular hydrogen bonding interaction and double bond, which favors molecular planarity and rigidity in the ground state and molecular flexibility in the excited state. Following this proposal, a particular class of NIR-II photothermal polymers are prepared. Their remarkable photothermal conversion efficiency is in good agreement with our strategy of coupling polymeric rigidity and flexibility, which accounts for the improved light absorption on going from the ground state to the excited state and nonradiative emission on going from the excited state to the ground state. It is envisioned that such a concept of coupling polymeric rigidity and flexibility will offer great inspiration for developing NIR-II photothermal polymers with the use of other chromophores.

Low bandgap and large deformation generally conflict each other. This work couples molecular rigidity and flexibility by intramolecular hydrogen bonds and double bonds to achieve NIR-II light absorption and reinforced internal conversion at the same time.     

Synthesis of a Near‐Infrared BODIPY Dye for Bioimaging and Photothermal Therapy

The development of robust photothermal agents for near‐infrared (NIR) imaging is a great challenge. Herein, we report the design and synthesis of a new photothermal agent, based on the aza‐boron‐dipyrromethene framework (azaBDP). This compound possessed excellent photostability and high photothermal‐conversion efficiency (50 %) under NIR laser irradiation. When the photothermal properties of this compound were utilized for tumor inhibition, stable long‐term fluorescence was observed in living animals. Photothermal treatment efficiently suppressed tumor growth, as evidenced by in vitro and in vivo experiments. Furthermore, NIR emission could be detected by using an imaging system and therapeutic self‐monitoring was achieved by using NIR imaging.     

基于快速热释放功能的相变偶氮苯/织物复合材料

针对偶氮基光敏分子存在放热速率慢和温度难以控制的难点,在分子结构设计基础上,采用氧化偶合法制备了具有固-液相变功能的4,4′-对-二正己基偶氮苯(AZO-L6).由于分子间作用力较低,偶氮苯分子呈现低熔、快异构化的特点,在发生反-顺异构化转变时大幅降低分子的熔点.固-液相变过程实现了光热能和相变焓的存储,在结构回复时同时放出储存的能量(231.8 kJ/kg),并将相变偶氮苯应用于可穿戴聚合物复合织物中.结果显示储能后的相变偶氮苯分子在蓝光(440 nm)刺激下在60 s内可将材料温度提升0.8℃,获得了具有自加热功能的可穿戴复合织物,为探索多功能自保温可穿戴装置提供了研究思路.     

Algae Extraction Controllable Delamination of Vanadium Carbide Nanosheets with Enhanced Near-Infrared Photothermal Performance

The two-dimensional (2D) vanadium carbide (V₂C) MXene has shown great potential as a photothermal agent (PTA) for photothermal therapy (PTT). However, the use of V₂C in PTT is limited by the harsh synthesis condition and low photothermal conversion efficiency (PTCE). Herein, we report a completely different green delamination method using algae extraction to intercalate and delaminate V₂AlC to produce mass V₂C nanosheets (NSs) with a high yield (90 %). The resulting V₂C NSs demonstrated good structural integrity and remarkably high absorption in near infrared (NIR) region with a PTCE as high as 48 %. Systemic in vitro and in vivo studies demonstrate that the V₂C NSs can serve as efficient PTA for photoacoustic (PA) and magnetic resonance imaging (MRI)-guided PTT of cancer. This work provides a cost-effective, environment-friendly, and high-yielding disassembly approach of MAX, opening a new avenue to develop MXenes with desirable properties for a myriad of applications.     

Supramolecular Photothermal Effects: A Promising Mechanism for Efficient Thermal Conversion

Supramolecular assemblies have been very successful in regulating the photothermal conversion efficiency of organic photothermal materials in a simple and flexible way, compared with conventional molecular synthesis. In these assemblies, it is the inherent physiochemical mechanism that determines the photothermal conversion, rather than the assembly strategy. This Minireview summarizes supramolecular photothermal effects, which refer to the unique features of supramolecular chemistry for regulating the photothermal conversion efficiency. Emphasis is placed on the mechanisms of how self‐assembly affects the photothermal performance. The supramolecular photothermal effects on various types of light‐harvesting species are discussed in detail. The timely interpretation of supramolecular photothermal effects is promising for the future design of the photothermal materials with high efficiency, precision, and multiple functionalities for a wide array of applications.     

Electronic Tuning of Mixed Quinoidal‐Aromatic Conjugated Polyelectrolytes: Direct Ionic Substitution on Polymer Main‐Chains

The synthesis of conjugated polymers with ionic substituents directly bound to their main chain repeat units is a strategy for generating strongly electron‐accepting conjugated polyelectrolytes, as demonstrated through the synthesis of a series of ionic azaquinodimethane (iAQM) compounds. The introduction of cationic substituents onto the quinoidal para‐azaquinodimethane (AQM) core gives rise to a strongly electron‐accepting building block, which can be employed in the synthesis of ionic small molecules and conjugated polyelectrolytes (CPEs). Electrochemical measurements alongside theoretical calculations indicate notably low‐lying LUMO values for the iAQMs. The optical band gaps measured for these compounds are highly tunable based on structure, ranging from 2.30 eV in small molecules down to 1.22 eV in polymers. The iAQM small molecules and CPEs showcase the band gap reduction effects of combining the donor‐acceptor strategy with the bond‐length alternation reduction strategy. As a demonstration of their utility, the iAQM CPEs so generated were used as active agents in photothermal therapy.     

Antibacterial Narrow‐Band‐Gap Conjugated Oligoelectrolytes with High Photothermal Conversion Efficiency

Two conjugated oligoelectrolytes (COEs), WMG1 and WMG2, were designed with the goal of achieving near infrared absorption and high photothermal conversion efficiency. Specifically, electron‐rich thiophene and electron‐poor benzo[1,2‐c:4,5‐c′]bis[1,2,5]thiadiazole subunits were introduced into the conjugated core to modulate the optical gap and to reduce the fluorescence emission efficiency. WMG1 and WMG2 show absorption maxima at around 800 nm, which favors tissue penetration. Although relatively small in size, WMG1 and WMG2 exhibit photothermal conversion efficiencies of circa 60 % and 54 %, respectively. WMG1 shows dark toxicity to the Gram positive bacterium B. subtilis and good photothermal killing efficiency toward both B. subtilis and Gram negative E. coli , features that demonstrate the promising potential of the COE molecular design for photothermal applications.     

Generating New Cross‐Relaxation Pathways by Coating Prussian Blue on NaNdF4 To Fabricate Enhanced Photothermal Agents

Cross‐relaxation among sensitizers is commonly regarded as deleterious in fluorescent materials, although favorable in photothermal agents. Herein, we coated Prussian blue (PB) on NaNdF₄ nanoparticles to fabricate core–shell nanocomplexes with new cross relaxation pathways between the ladder‐like energy levels of Nd³⁺ ions and continuous energy band of PB. The photothermal conversion efficiency was improved exceptionally and the mechanism of the enhanced photothermal effect was investigated. In vivo photoacoustic imaging and photothermal therapy demonstrated the potential of the enhanced photothermal agents. Moreover, the concept of generating new cross‐relaxation pathways between different materials is proposed to contribute to the design of all kinds of enhanced photothermal agents.     

Spindle‐Like Polypyrrole Hollow Nanocapsules as Multifunctional Platforms for Highly Effective Chemo–Photothermal Combination Therapy of Cancer Cells in Vivo

The monodispersed spindle‐like polypyrrole hollow nanocapsules (PPy HNCs) as the multifunctional platforms for combining chemotherapy with photothermal therapy for cancer cells are reported. Whereas the hollow cavity of nanocapsules can be used to load the anticancer drug (i.e., doxorubicin) for chemotherapy, the PPy shells can convert NIR light into heat for photothermal therapy. The release of the drug from the spindle‐like PPy HNCs is pH‐sensitive and near‐infrared (NIR) light‐enhanced. More importantly, the spindle‐like PPy HNCs can penetrate cells more rapidly and efficiently in comparison with the spherical PPy HNCs. Both in vitro and in vivo experiments demonstrated that the combination of DOX‐loaded spindle‐like PPy HNCs and NIR light provide a highly effective and feasible chemo‐photothermal therapy cancer method with a synergistic effect. Owing to their high photothermal conversion efficiency, large hollow cavity, and good biocompatibility, the spindle‐like PPy HNCs could be used as a promising new cancer drug‐nanocarrier and photothermal agent for localized tumorous chemo‐photothermal therapy.     

Recent advances in photothermal and RNA interfering synergistic therapy

As a new treatment technique,photothermal therapy(PTT) has aroused worldwide attention in cancer treatment,mainly due to its excellent absorption ability,easy regulation,and biodegradability.Photothermal conversion materials with enhanced permeability and retention effect can be targeted easily to tumor tissue.They can accumulate efficiently to tumor tissues and allow normal tissues and organs not to be affected by temperature,thus significantly helping to reduce the systemic toxicity and improve the antitumor effect.However,PTT alo ne often suffers from the rapeutic resistance and reduced therapeutic efficacy,due to photothermal nanomaterial-mediated fundamental cellular defense mechanism of heat shock response,which could be inhibited by small interfering RNA(siRNA).Nevertheless,photothermal conversion materials as an excellent siRNA delivery carrier may conside rably enhance the delivery efficiency of siRNA.Therefore,photothermal and RNA interfering(RNAi) synergistic therapy has recently aroused extensive attention in tumor treatment.In this review,we mainly summarize the recent advances of photothermal and RNAi synergistic therapy,including some synergistic therapeutic nanoplatforms of inorganic and organic photothermal materials and other combined therapies such as combining with small molecular antitumor agents or PDT/imaging.The combination of various treatment techniques may considerably improve the synergistic therapeutic effect of PTT and RNAi in the treatment of cancers.     

Highly Efficient Organic Blue Electroluminescent Materials and Devices with Mesoscopic Structures

Due to the difficulty in achieving high efficiency and high color purity simultaneously, blue emission is the limiting factor for the performance and stability of OLEDs. Since 2003, we have been working on organic light‐emitting diodes (OLEDs), especially on blue light. After a series of molecular designs, novel strategies have been proposed from different aspects. At first, highly efficient deep blue emission could be achieved through molecular design with highly twisted structure to suppress fluorescence quenching and redshift. Deep blue emitters with high efficiency in solid state, a twisted structure with aggregation induced emission (AIE) characteristics was incorporated to inhibit molecular aggregation, and triplet‐triplet fusion (TTF) and hybridized localized charge transfer (HLCT) were adopted to increase the ratio of triplet exciton used. Secondly, a highly efficient blue OLED could be achieved through improving charge transport. New electron transport materials (ETMs) with wide band gap were developed to control charge transport balance in devices. Thirdly, a highly efficient deep blue emission could be achieved through a mesoscopic structure of out‐coupling layer. A mesoscopic photonic structured organic thin film was fabricated on the top of metal electrode by self‐aggregation in order to improve the light out‐coupling efficiency.     

2D Monoelemental Germanene Quantum Dots: Synthesis as Robust Photothermal Agents for Photonic Cancer Nanomedicine

As a new family member of the emerging two‐dimensional (2D) monoelemental materials (Xenes), germanene has shown promising advantages over the prototypical 2D Xenes, such as black phosphorus (BP) and graphene. However, efficient manufacture of novel germanene nanostructures is still a challenge. Herein, a simple top‐down approach for the liquid‐exfoliation of ultra‐small germanene quantum dots (GeQDs) is presented. The prepared GeQDs possess an average lateral size of about 4.5 nm and thickness of about 2.2 nm. The functionalized GeQDs were demonstrated to be robust photothermal agents (PTAs) with outstanding photothermal conversion efficacy (higher than those of graphene and BPQDs), superior stability, and excellent biocompatibility. As a proof‐of‐principle, 2D GeQDs‐based PTAs were used in fluorescence/photoacoustic/photothermal‐imaging‐guided hyperpyrexia ablation of tumors. This work could expand the application of 2D germanene to the field of photonic cancer nanomedicine.     

Vinyl Sulfonate Esters: Efficient Chain Transfer Agents for the 3D Printing of Tough Photopolymers without Retardation

The formation of networks through light‐initiated radical polymerization allows little freedom for tailored network design. The resulting inhomogeneous network architectures and brittle material behavior of such glassy‐type networks limit the commercial application of photopolymers in 3D printing, biomedicine, and microelectronics. An ester‐activated vinyl sulfonate ester (EVS) is presented for the rapid formation of tailored methacrylate‐based networks. The chain transfer step induced by EVS reduces the kinetic chain length of the photopolymer, thus shifting the gel point to higher conversion, which results in reduced shrinkage stress and higher overall conversion. The resulting, more homogeneous network is responsible for the high toughness of the material. The unique property of EVS to promote nearly retardation‐free polymerization can be attributed to the fact that after the transfer step no polymerizable double bond is formed, as is usually seen in classical chain transfer agents. Laser flash photolysis, theoretical calculations, and photoreactor studies were used to elucidate the fast chain transfer reaction and exceptional regulating ability of EVS. Final photopolymer networks exhibit improved mechanical performance making EVS an outstanding candidate for the 3D printing of tough photopolymers.     

NIR‐Induced Disintegration of CuS‐Loaded Nanogels for Improved Tumor Penetration and Enhanced Anticancer Therapy

Nanocarrier‐based cancer therapy suffers from poor tumor penetration and unsatisfied therapeutical efficacy, as its vascular extravasation efficiency is often compromised by the intrinsic physiological heterogeneity in tumor tissues. In this work, novel near infrared (NIR)‐responsive CuS‐loaded nanogels are prepared to deliver anticarcinogen into the tumor. These hybrid polymeric nanogels possess high photothermal conversion efficiency, and are able to load a large amount of antitumor drug (e.g., doxorubicin [DOX]). More importantly, the thermal heat could induce self‐destruction of the big‐size framework of hybrid nanogels into small nanoparticles, which greatly facilitates tumor penetration to release DOX deep inside the tumor, as validated by photoacoustic (PA) imaging which exhibits 26.3 times enhancement at the interior region compared to signals of groups without laser irradiation. Such structural alteration, combined with strong photothermal and chemotherapy effects, leads to remarkable inhibition of tumor growth in mice. As a result, this NIR‐induced disintegration of CuS‐loaded nanogels provides a novel drug delivery strategy and might open a new window for clinical cancer treatment.