Near-Infrared-II Fluorophore with Inverted Dependence of Fluorescence Quantum Yield on Polarity as Potent Phototheranostics for Fluorescence-Image-Guided Phototherapy of Tumors

Preparation of protoporphyrin IX loaded nanostructured lipid carriers for anticancer photodynamic therapy

Photodynamic therapy (PDT) is a promising strategy for cancer treatment. However, the poor hydrophilicity of most photosensitizers makes them difficult to enter the cells and also susceptible to aggregation-induced quenching in aqueous environment. In this study, we encapsulated protoporphyrin IX (PPIX) by nanostructured lipid carrier to obtain a water-soluble PPIX delivery system (NLC-PPIX). The nanoparticles exhibited high colloidal stability and good fluorescence emission. The generation of 1O2 from the NLC-PPIX was verified using 9,10-anthracenediyl-bis(methylene)dicarboxylic acid (ABDA) as 1O2 indicator. The 1O2 quantum yield of the NLC-PPIX in aqueous solution was calculated to be ∼9%. The flow cytometry and fluorescence imaging confirmed the uptake of NLC-PPIX by the A2058 cells and the generation of 1O2 inside the cells under light excitation. The in vitro cytotoxicity assay showed that the NLC-PPIX exerted no toxicity on the A2058 cells under dark conditions, while light irradiation triggered high phototoxicity. The cell viability of the A2058 cells was significantly decreased and the inhibition rate reached approximately 96% by treating the cells with 200 μg/mL NLC-PPIX and 420 nm light irradiation. The successful cancer cell uptake and PDT effect revealed the therapeutic promise of our drug delivery system.

The Role of Open-Shell Organic Radical in Enhancing Anti-Tumor Photocatalysis Reaction of NIR Light-Activated Photosensitizer

Open-shell radical materials, which are characterized by unpaired electrons, have led to revolutionary breakthroughs in material science due to their unique optoelectronic properties. However, the involvement of organic radicals in photodynamic therapy (PDT) has rarely been reported or discussed. This work studies two photosensitizer analogs. 4AM-OS with extended π-conjugation exhibits open-shell radical characters and enhanced type-I photodynamic activity compared with closed-shell 2AM-CS. 4AM-OS displays the thermally accessible triplet-state character, resulting in more unpaired electrons delocalized along the π-conjugated backbone at higher temperatures. Accordingly, the temperature-dependent photodynamic activity of 4AM-OS confirms its association with the open-shell electronic structure. As the unpaired electrons in open-shell 4AM-OS are more delocalized and generate additional electronic energy states, photo-induced charge transfer is promoted to facilitate type-I photodynamic reactions. This observation addresses the challenge associated with near-infrared (NIR) photosensitizers, such as 4AM-OS, which often demonstrate low efficacy in PDT due to the limited energy provided by NIR light despite its superior tissue penetration depth. Overall, clarifying the beneficial role of organic radicals in photodynamic reactions will bring revolutionary breakthroughs to developing high-performance NIR photosensitizers and promoting the efficacy of PDT for deep-seated lesions.

Achieving Ultrabright NIR-II Nanofluorophore for In Vivo Imaging by Inhibiting H-Aggregates Formation

Small molecules with an acceptor-donor-acceptor (A-D-A) structure, featuring a fused-ring core as the donor and two electron-withdrawing end groups as acceptor units, represent a potential option for NIR-II fluorophores, benefiting from their narrow bandgaps, superior light-harvesting capabilities, and exceptional photostabilities. However, their planar conformations predispose them to forming H-aggregates during self-assembly, leading to significantly reduced fluorescence quantum yield (QY) of the resulting nanofluorophores. Herein, we report a small molecule, PF8CN, with a terminal unit-A-D-A-terminal unit structure. The terminal units of 3,5-bis(octyloxy)phenyl group result in a twisted conformation for PF8CN, preventing face-to-face stacking and thereby inhibiting the formation of H-aggregates. Consequently, the NIR-II fluorescence QY of PF8CN NPs is 3.8 times that of the model nanofluorophore (F8CN NPs), which contains a substantial amount of H-aggregates. The NIR-II brightness of PF8CN NPs is 5.3- and 14.9-times that of F8CN NPs and ICG/FBS, respectively, at an equal molar concentration. Such ultrahigh NIR-II brightness of PF8CN NPs allows us to perform long-term and real-time NIR-II fluorescence imaging of cerebral and hindlimb vessels, as well as the thrombolytic process. This work provides an effective method for producing nanofluorophores with ultrahigh NIR-II brightness, positioning PF8CN NPs as a strong contender in the field of NIR-II nanofluorophores.

Alleviating NIR-II emission quenching in ring-fused fluorophore via manipulating dimer populations for superior fluorescence imaging

Emission quenching resulting from fluorophore aggregation has long been a significant challenge in optimizing emission-based technologies, such as fluorescence imaging and optoelectronic devices. Alleviating this quenching in aggregates is crucial, yet progress is impeded by the limited understanding of the nature and impact of aggregates on emission. Here, we elucidate the critical role of dimeric aggregate (dimer) in alleviating second near-infrared (NIR-II, 900-1700 nm) emission quenching from ring-fused fluorophore 4F for superior fluorescence imaging. Spectral decomposition and molecular dynamics simulations demonstrate the predominance of dimer populations in 4F aggregates. Notably, dimers exhibit significantly weaker emission but intense intermolecular nonradiative (interNR) decay compared to monomers, as demonstrated by ultrafast spectra and quantum calculation. Therefore, the predominant population of dimers with weak emission and pronounced interNR feature underlies the emission quenching in 4F aggregates. This discovery guides the preparation of ultrabright NIR-II 4F nanofluorophore (4F NP3s) by decreasing dimer populations, which show 5-fold greater NIR-II brightness than indocyanine green, enabling superior resolution in visualizing blood vessels. This work offers valuable insights into aggregation-caused quenching, with broad implications extending far beyond NIR-II fluorescence imaging.

Water-soluble AIE photosensitizer in short-wave infrared region for albumin-enhanced and self-reporting phototheranostics

Organic photosensitizers (PSs) play important roles in phototheranostics, and contribute to the fast development of precision medicine. However, water-soluble and highly emissive organic PSs, especially those emitting in the short-wave infrared region (SWIR), are still challenging. Also, it's difficult to prepare self-reporting PSs for visualizing the treatment via stimulated emission depletion (STED) nanoscopy. Thus, in this work, a water-soluble molecule of DTPAP-TBZ-I with aggregation-induced emission features is designed for the self-reporting photodynamic therapy (PDT) in an ultra-high resolution. In contrast to single molecule, its complex (DTPAP-TBZ-I@BSA) shows much enhanced fluorescence properties and reactive oxygen species (ROS) generation in SWIR window. Their photoluminescence quantum yield is determined to be ∼20.6 % and the enhancement of ROS generation is ∼18-fold. During the PDT, immigration of the complex from cytoplasm to nucleus is also observed via STED nanoscopy with a resolution of 66.11 nm, which allows self-report in the PDT treatment. DTPAP-TBZ-I@BSA is finally utilized for the imaging-guided PDT in vivo with a tumor inhibition rate of 84 %. This is the first work in albumin-enhanced water-soluble organic PSs in SWIR window for self-reporting phototheranostics at ultra-high resolutions, providing an ideal solution for the next generation of photosensitizers for precise medicine.

Molecular Trojan Based on Membrane-Mimicking Conjugated Electrolyte for Stimuli-Responsive Drug Release

Enhancing payload encapsulation stability while enabling controlled drug release are both critical objectives in drug delivery systems but are challenging to reconcile. This study introduces a zwitterionic conjugated electrolyte (CE) molecule named Zwit, which acts as a molecular Trojan by mimicking the lipid bilayers. When integrated into liposome membranes, Zwit rigidifies the bilayer structure likely due to its hydrophobic interactions providing structural support, thus inhibiting drug leakage. Upon 808 nm laser excitation, Zwit rapidly accelerates DOX release from liposome core, likely due to light-triggered conformational changes or photothermal effects that compromise membrane permeability. These findings demonstrate Zwit's ability to overcome the challenge of simultaneously preventing premature payload leakage and enabling stimuli-responsive drug release with a single component. Additionally, Zwit exhibits excellent biocompatibility with membranes, outperforming its quaternary ammonium counterpart and commonly used dye indocyanine green (ICG). By harnessing its NIR-II emission, Zwit enables durable in vivo biodistribution tracking of nanocarriers, whereas ICG suffers from significant dye leakage. In subcutaneous tumor models, the synergistic effects of chemotherapy and thermotherapy facilitated by this light-triggered system induced a potent antitumor immune response, further enhancing anticancer efficacy. This work underscores the potential of membrane-mimicking CEs as multifunctional tools in advanced drug delivery systems.

Bilateral Synergistic Effects of Phototherapy-Based NIR-II Absorption Photosensitizer for Allergic Rhinitis

Allergic rhinitis (AR) is the most prevalent global health issue, affecting approximately 3 billion people, with its incidence increasing annually. The current first-line pharmacotherapy for symptom relief has limited efficacy and often results in notable side effects. Here, aza-BODIPY-based nanoparticles (RH@NPs) are developed that exhibit mild photothermal therapy (PTT) and type I photodynamic therapy (PDT) capabilities. Enhanced intramolecular charge transfer induces NIR-II absorption of the photosensitizer (RH), facilitating deeper tissue penetration for augmented AR therapy. Additionally, the use of an asymmetric donor-acceptor-acceptor' configuration promotes the self-assembly of RH, enhancing its intersystem crossing ability and enabling efficient photophysical activity. The synergistic effects of PTT (enhancing HSF1 DNA-binding activity to inhibit epithelial-mesenchymal transition by epigenetically regulating the expression of epithelial-mesenchymal transition-associated genes) and PDT (activating NRF2 transcriptional activity to stimulate the antioxidant defense system) enable RH@NPs to provide a superior therapeutic effect in a mouse model of AR. This effect is achieved by mechanically reducing the allergic response rather than merely alleviating symptoms. Notably, the photosensitizer-based physical therapy demonstrates enhanced safety. This study is the first to successfully investigate the application of phototherapy for AR and elucidate its mechanism of action, offering a novel, straightforward, and efficient treatment strategy for AR.

Side Chain Phenyl Isomerization-Induced Spatial Conjugation for Achieving Efficient Near-Infrared II Phototheranostic Agents

The contradiction of near-infrared II (NIR-II) emission and photothermal effects limits the development of phototheranostic agents (PTAs) in many emerging cutting-edge applications. Organic aggregates present a promising opportunity for the balance of competitive relaxation processes through the manipulation of molecular structure and packing. Herein, side chain phenyl isomerization-induced spatial conjugation was proposed for constructing A-D-A type NIR-II PTAs with simultaneous enhancement of fluorescence brightness and photothermal properties. Three pairs of mutually isomeric fluorophores, whose phenyls respectively located at the outside (o-series) and inside (i-series) of the side chain, were designed and synthesized. The positional isomerization of the phenyl endows the o-series crystals with strong spatial conjugation between the phenyl group on the side chain and the backbone, as well as interlocked planar network, which is different to that observed in the i-series. Thus, all o-series nanoparticles (NPs) exhibit red-shifted absorption, enhanced NIR-II emission, and superior photothermal properties than their i-series counterparts. A prominent member of the o-series, o-ITNP NPs, demonstrated efficacy in facilitating NIR-II angiography, tumor localization, and NIR-II imaging-guided tumor photothermal therapy. The success of this side chain phenyl isomerization strategy paves the way for precise control of the aggregation behavior and for further development of efficient NIR-II PTAs.

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.

Highly Stable Near-Infrared II Luminescent Diradicaloids for Cancer Phototheranostics

Near-infrared II (NIR-II) phototheranostic agents have become prominent agents for the early diagnosis and precise treatment of cancer. Organic open-shell diradicaloids with distinct structure and narrow band gap are promising candidates for phototherapeutic agents due to their strong spin-coupling effect and NIR light-harvesting capacity. However, achieving stable and efficient NIR-II luminescent diradicaloids is crucial yet rather challenging considering their high chemical reactivity and self-absorption. Herein, two highly stable NIR-II luminescent diradicaloids, 2PhNVDPP and PhNVDPP, were successfully fabricated by employing an acceptor planarization/π-conjugation extension and donor rotation strategy. After encapsulation into water-dispersible nanoparticles (NPs), 2PhNVDPP NPs exhibit NIR-II luminescence, high PCE of 53%, and improved photo/heat stability. In vivo experiments with 2PhNVDPP NPs demonstrated the clear visualization of blood vessels and tumors, as well as the successful NIR-II imaging-guided photothermal ablation of tumors. This study not only develops a pioneering stable diradicaloid phototherapeutic agent with NIR-II luminescence but also provides a unique perspective for the effectiveness of multimodal anticancer therapy.

Facilely Achieving Near-Infrared-II J-Aggregates through Molecular Bending on a Donor-Acceptor Fluorophore for High-Performance Tumor Phototheranostics

Constructing J-aggregated organic dyes represents a promising strategy for obtaining biomedical second near-infrared (NIR-II) emissive materials, as they exhibit red-shifted spectroscopic properties upon assembly into nanoparticles (NPs) in aqueous environments. However, currently available NIR-II J-aggregates primarily rely on specific molecular backbones with intricate design strategies and are susceptible to fluorescence quenching during assembly. A facile approach for constructing bright NIR-II J-aggregates using prevalent donor-acceptor (D-A) molecules is still lacking. In this study, we present a facile method that transforms D-A molecules into J-aggregates by simply bending the molecule through introducing a methyl group, enabling high-performance NIR-II phototheranostics. The TAA-BT-CN molecule exhibits hypsochromic-shift absorption upon forming H-aggregated NPs, while the designed mTAA-BT-CN with a bent structure demonstrates a bathochromic shift of over 100 nm in absorption upon forming J-aggregated NPs, leading to much enhanced NIR-II emission beyond 1100 nm. With respect to its H-aggregated counterpart with the aggregation-caused quenching (ACQ) phenomenon, the J-aggregated mTAA-BT-CN NPs exhibit a 7-fold increase in NIR-II fluorescence owing to their aggregation-induced emission (AIE) property as well as efficient generation of heat and reactive oxygen species under 808 nm light excitation. Finally, the mTAA-BT-CN NPs are employed for whole-body blood vessel imaging using NIR-II technology as well as imaging-guided tumor phototherapies. This study will facilitate the flourishing advancement of J-aggregates based on prevalent D-A-type molecules.

High-Performance NIR-II Fluorescent Type I/II Photosensitizer Enabling Augmented Mild Photothermal Therapy of Tumors by Disrupting Heat Shock Proteins

NIR-II fluorescent photosensitizers as phototheranostic agents hold considerable promise in the application of mild photothermal therapy (MPTT) for tumors, as the reactive oxygen species generated during photodynamic therapy can effectively disrupt heat shock proteins. Nevertheless, the exclusive utilization of these photosensitizers to significantly augment the MPTT efficacy has rarely been substantiated, primarily due to their insufficient photodynamic performance. Herein, the utilization of high-performance NIR-II fluorescent type I/II photosensitizer (AS21:4) is presented as a simple but effective nanoplatform derived from molecule AS2 to enhance the MPTT efficacy of tumors without any additional therapeutic components. By taking advantage of heavy atom effect, AS21:4 as a type I/II photosensitizer demonstrates superior efficacy in producing 1O2 (1O2 quantum yield = 12.4%) and O2 •- among currently available NIR-II fluorescent photosensitizers with absorption exceeding 800 nm. In vitro and in vivo findings demonstrate that the 1O2 and O2 •- generated from AS21:4 induce a substantial reduction in the expression of HSP90, thereby improving the MPTT efficacy. The remarkable phototheranostic performance, substantial tumor accumulation, and prolonged tumor retention of AS21:4, establish it as a simple but superior phototheranostic agent for NIR-II fluorescence imaging-guided MPTT of tumors.

A singular plasmonic-thermoelectric hollow nanostructure inducing apoptosis and cuproptosis for catalytic cancer therapy

Thermoelectric technology has recently emerged as a distinct therapeutic modality. However, its therapeutic effectiveness is significantly limited by the restricted temperature gradient within living organisms. In this study, we introduce a high-performance plasmonic-thermoelectric catalytic therapy utilizing urchin-like Cu2-xSe hollow nanospheres (HNSs) with a cascade of plasmonic photothermal and thermoelectric conversion processes. Under irradiation by a 1064 nm laser, the plasmonic absorption of Cu2-xSe HNSs, featuring rich copper vacancies (VCu), leads to a rapid localized temperature gradient due to their exceptionally high photothermal conversion efficiency (67.0%). This temperature gradient activates thermoelectric catalysis, generating toxic reactive oxygen species (ROS) targeted at cancer cells. Density functional theory calculations reveal that this vacancy-enhanced thermoelectric catalytic effect arises from a much more carrier concentration and higher electrical conductivity. Furthermore, the exceptional photothermal performance of Cu2-xSe HNSs enhances their peroxidase-like and catalase-like activities, resulting in increased ROS production and apoptosis induction in cancer cells. Here we show that the accumulation of copper ions within cancer cells triggers cuproptosis through toxic mitochondrial protein aggregation, creating a synergistic therapeutic effect. Tumor-bearing female BALB/c mice are used to evaluate the high anti-cancer efficiency. This innovative approach represents the promising instance of plasmonic-thermoelectric catalytic therapy, employing dual pathways (membrane potential reduction and thioctylated protein aggregation) of mitochondrial dysfunction, all achieved within a singular nanostructure. These findings hold significant promise for inspiring the development of energy-converting nanomedicines.

Emerging A-D-A fused-ring photosensitizers for tumor phototheranostics

As we all know, cancer is still a disease that we are struggling against. Although the traditional treatment options are still the mainstream in clinical practice, emerging phototheranostics technologies based on photoacoustic or fluorescence imaging-guided phototherapy also provide a new exploration direction for non-invasive, low-risk and highly efficient cancer treatment. Photosensitizers are the core materials to accomplish this mission. Recently, more attention has been paid to the emerging A-D-A fused-ring photosensitizers. A-D-A fused-ring photosensitizers display strong and wide absorption spectra, high photostability and easy molecular modification. Since this type of photosensitizer was first used for tumor therapy in 2019, its application boundaries are constantly expanding. Therefore, in this feature article, from the perspective of molecular design, we focused on the development of these molecules for application in phototheranostics over the past five years. The effects of tiny structural changes on their photophysical properties are discussed in detail, which provides a way for structural optimization of the subsequent A-D-A photosensitizers.

Neutral Cyanine: Ultra-Stable NIR-II Merocyanines for Highly Efficient Bioimaging and Tumor-Targeted Phototheranostics

Fluorescence imaging (FLI)-guided phototheranostics using emission from the second near-infrared (NIR-II) window show significant potential for cancer diagnosis and treatment. Clinical imaging-used polymethine ionic indocyanine green (ICG) dye is widely adopted for NIR fluorescence imaging-guided photothermal therapy (PTT) research due to its exceptional photophysical properties. However, ICG has limitations such as poor photostability, low photothermal conversion efficiency (PCE), short-wavelength emission peak, and liver-targeting issues, which restrict its wider use. In this study, two ionic ICG derivatives are transformed into neutral merocyanines (mCy) to achieve much-enhanced performance for NIR-II cancer phototheranostics. Initial designs of two ionic dyes show similar drawbacks as ICG in terms of poor photostability and low photothermal performance. One of the modified neutral molecules, mCy890, shows significantly improved stability, an emission peak over 1000 nm, and a high photothermal PCE of 51%, all considerably outperform ICG. In vivo studies demonstrate that nanoparticles of the mCy890 can effectively accumulate at the tumor sites for cancer photothermal therapy guided by NIR-II fluorescence imaging. This research provides valuable insights into the development of neutral merocyanines for enhanced cancer phototheranostics.

Design of a high-performance NIR-II nanoprobe by steric regulation for in vivo vasculature and tumor imaging

A novel NIR-II nanoprobe was developed through regulating the steric effect of an A-DA'D-A dye. The probe features the properties of strong fluorescence, high stability, and a large Stokes shift, thereby serving as a remarkable contrast agent for the fluorescence imaging of hindlimb vasculature and tumors in live mice.

Supramolecular engineering cascade regulates NIR-II J-aggregates to improve photodynamic therapy

Rational design of small organic molecule-based NIR-II photosensitizers (PSs) with high singlet oxygen quantum yield in aqueous solution for deep tissue imaging and cancer therapy still presents challenges. Herein, we devised a general synthesis strategy to obtain six NIR-II region PSs with tunable aggregation states by adjusting the steric effect, and all PSs possess longer NIR absorption/emission wavelengths with tails extending beyond 1200 nm. Notably, ATX-6 possessed a singlet oxygen quantum yield of 38.2% and exhibited concentration-dependent J-aggregation properties upon self-assembly in an aqueous solution. What's more, supramolecular engineering with DSPE-PEG2000 further enhanced its degree of J-aggregation, which was attributed to the dimer-excited reduction of the energy levels of the single-linear/triple-linear states and the facilitation of intersystem crossover processes. In addition, ATX-6 NPs showed superior photodynamic therapy effects and great potential in high-contrast in vivo bioimaging of the NIR-II region. These results provide valuable insights for achieving the diagnostic and therapeutic integration of tumors.

An Asymmetric NIR-II Organic Fluorophore with an Ultra-Large Stokes Shift for Imaging-Guided and Targeted Phototherapy

NIR-II imaging-guided phototherapy is an attractive, yet challenging, tumor treatment strategy. By monitoring the accumulation of phototherapy reagents at the tumor site through imaging and determining the appropriate therapy window, the therapeutic effect could be significantly improved. Probes with NIR-II (1000-1700 nm) fluorescence emission and a large Stokes shift hold great promise for fluorescence imaging with deep penetration, minimized self-quenching, and high spatiotemporal resolution. However, due to the lack of a suitable molecular framework, the design of a simple small-molecule dye with a large Stokes shift and NIR-II fluorescence emission has rarely been reported. Herein, we prepare an asymmetric D-π-A type NIR-II fluorescence probe (TBy). The probe is incapsulated in an amphiphilic polymer and modified with a fibronectin targeting peptide CREKA, which could recognize the fibrin-fibronectin complex overexpressed in multiple malignant tumors. The nanoparticles thus constructed (TByC-NPs) have maximum fluorescence emission at 1037 nm with a large Stokes shift of 426 nm, which is the largest Stokes shift among organic NIR-II fluorescent dyes reported in the literature. The TByC-NPs exhibit a good NIR-II imaging performance, active tumor targeting, and good photothermal and photodynamic capabilities. In vitro and in vivo studies verify that the TByC nanoplatform shows outstanding biocompatibility for NIR-II imaging-guided phototherapy and provides an excellent antitumor effect.

Polydopamine-Mediated Metal-Organic Frameworks Modification for Improved Biocompatibility

Engineered nanomaterials are promising in biomedical application. However, insufficient understanding of their biocompatibility at the cellular and organic levels prevents their widely biomedical applications. Metal-organic frameworks (MOFs) have attracted increasing attention in recent years. In this work, zeolitic imidazolate framework-8 (ZIF-8) and polydopamine (PDA)-modified ZIF-8 are chosen as model nanomaterials due to its emergent role in nanomedicine. In vitro, the results demonstrate that the PDA coating greatly alleviates the cytotoxicity of ZIF-8 to RAW264.7, LO2, and HST6, which represent three different cell types in liver organs. Mechanistically, ZIF-8 entering into the cells can greatly induce the reactive oxygen species generation, which subsequently induces cell cycle delay and autophagy, ultimately leads to enhanced cytotoxicity. Further, human umbilical vein endothelial cells model and zebrafish embryos assay also confirm that PDA can compromise the ZIF-8 toxicity significantly. This study reveals that PDA-coated MOFs nanomaterials show great potential in nano-based drug delivery systems .

Deciphering Oxygen-Independent Augmented Photodynamic Oncotherapy by Facilitating the Separation of Electron-Hole Pairs

Developing Type-I photosensitizers provides an attractive approach to solve the dilemma of inadequate efficacy of photodynamic therapy (PDT) caused by the inherent oxygen consumption of traditional Type-II PDT and anoxic tumor microenvironment. The challenge for the exploration of Type-I PSs is to facilitate the electron transfer ability of photosensitization molecules for transforming oxygen or H2O to reactive oxygen species (ROS). Herein, we propose an electronic acceptor-triggered photoinduced electron transfer (a-PET) strategy promoting the separation of electron-hole pairs by marriage of two organic semiconducting molecules of a non-fullerene scaffold-based photosensitizer and a perylene diimide that significantly boost the Type-I PDT pathway to produce plentiful ROS, especially, inducing 3.5-fold and 2.5-fold amplification of hydroxyl (OH⋅) and superoxide (O2 -⋅) generation. Systematic mechanism exploration reveals that intermolecular electron transfer and intramolecular charge separation after photoirradiation generate a competent production of radical ion pairs that promote the Type-I PDT process by theoretical calculation and ultrafast femtosecond transient absorption (fs-TA) spectroscopy. By complementary tumor diagnosis with photoacoustic imaging and second near-infrared fluorescence imaging, this as-prepared nanoplatform exhibits fabulous photocytotoxicity in harsh hypoxic conditions and terrific cancer revoked abilities in living mice. We envision that this work will broaden the insight into high-efficiency Type-I PDT for cancer phototheranostics.

Ultrabright NIR-II Nanoprobe for Image-Guided Accurate Resection of Tiny Metastatic Lesions

Fluorescence imaging is a vital way to delineate the tumor boundaries. Here, we achieve a NIR-II aggregation-induced emission luminogen (AIEgen) with a fluorescence quantum yield (QY) of 12.6% in water through straightforward alkyl side chain modification. After loading of NIR-II AIEgen into polystyrene (PS) nanospheres, the thermal deactivation pathway is extremely limited, thereby concentrating absorption excitation on fluorescence emission. The fluorescence intensity is further enhanced by 5.4 times, the QY increases to 21.1%, and the NIR-II imaging signal is accordingly enhanced by 8.7 times, surpassing conventional DSPE-PEG carriers. The NIR-II@PS nanoprobe showcases superior resolution and tissue penetration depth compared to indocyanine green (ICG) and short-range near-infrared AIEgens. In vivo investigations underscore its tumor-to-normal tissue ratio (3.9) at 24 h post intravenous injection, enabling complete resection of ≤1 mm metastases under NIR-II bioimaging guidance. Additionally, the PS carrier-nanoparticles exhibit low toxicity in vivo, laying a promising foundation for the future design of medical nanomaterials.

A novel polymer enabled by polymerized small molecule strategy for tumor photothermal and photodynamic therapy

Photothermal therapy (PTT) and photodynamic therapy (PDT) are effective method for tumor treatment. However, the limited variety and quantity of photothermal agents (PTAs) and photosensitizer (PSs) are still major challenges. Moreover, the cell apoptosis mechanism induced by PDT and PTT is still elusive. A fused-ring small molecule acceptor-donor acceptor' donor-acceptor (A-DA'D-A) type of Y5 (Scheme 1) has a narrow band-gap and strong light absorption. Herein, we used Y5 to polymerize with thiophene unit to obtain polymer PYT based on polymerized small molecule strategy, and PYT nanoparticles (PYT NPs) was prepared via one-step nanoprecipitation strategy with DSPE-PEG2000. PYT NPs had excellent biocompatibility, good photostability, high photothermal conversion efficiency (67%) and reactive oxygen species (ROS) production capacity under 808 nm laser irradiation (PYT NPs + NIR). In vitro and in vivo experiments revealed that PYT NPs + NIR had the ability to completely ablate tumor cells. It was demonstrated that cell apoptosis induced by PYT NPs + NIR was closely related to mitochondrial damage. This study provides valuable guidance for constructing high-performance organic PTAs and PSs for tumor treatment. Scheme 1 PYT enabled by polymerized small molecule strategy for tumor photothermal and photodynamic therapy.