ECL cytosensor for sensitive and label-free detection of circulating tumor cells based on hierarchical flower-like gold microstructures.

The development of sensitive and efficient cell sensing strategies to detect circulating tumor cells (CTCs) in peripheral blood is crucial for the early diagnosis and prognostic assessment of cancer clinical treatment. Herein, an array of hierarchical flower-like gold microstructures (HFGMs) with anisotropic nanotips was synthesized by a simple electrodeposition method and used as a capture substrate to construct an ECL cytosensor based on the specific recognition of target cells by aptamers. The complex topography of the HFGMs array not only catalyzed the enhancement of ECL signals, but also induced the cells to generate more filopodia, improving the capture efficiency and shortening the capture time. The effect of topographic roughness on cell growth and adhesion propensity was also investigated, while the cell capture efficiency was proposed to be an important indicator affecting the accuracy of the ECL cytosensor. In addition, the capture of cells on the electrode surface increased the steric hindrance, which caused ECL signal changes in the Ru(bpy)32+ and TPrA system, realizing the quantitative detection of MCF-7 cells. The detection range of the sensor was from 102 to 106 cells mL-1 and the detection limit was 18 cells mL-1. The proposed detection method avoids the process of separation, labeling and counting, which has great potential for sensitive detection in clinical applications.

Dark-field imaging and fluorescence dual-mode detection of microRNA-21 in living cells by core-satellite plasmonic nanoprobes.

The in situ precise quantification and simultaneous imaging of low abundance microRNAs (miRNAs) within living cells is critical for cancer diagnosis, yet it remains a significant challenge. Leveraging the excellent sensitivity and spatiotemporal resolution of dark-field microscopy (DFM) and fluorescence imaging, we have successfully devised a novel detection approach using dual-signal reporter probes (DSRPs). These probes allow for highly sensitive detection of miRNA-21 in living cells via toehold-mediated strand displacement cascades. The DSRPs were constructed by Au nanoparticles and Ag nanoclusters core-satellite nanostructures. After the recognition of miRNA-21, the strand displacement cascades were triggered, inducing the disassembly of the Au/Ag core-satellite nanostructure with apparent scattering intensity decrease and peak wavelength shifts. Additionally, the fluorescence of Ag clusters could be recovered and further enhanced when in close proximity to specific guanine-rich strands. The dual-signal response capability enables the accurate detection of miRNA-21 from 1 fM to 1 nM, with a limit of detection reached 0.75 fM. DFM and fluorescent imaging of living cells efficiently confirms the applicable detection of miRNA-21 in complex detection media. The biosensor based on DSRPs represents a promising nanoplatform for visual monitoring and imaging of biomolecules in living cells, even at the single particle level.

A noncovalent backbone planarization strategy increases the NIR-II extinction coefficients for gas/phototheranostic applications.

We propose a noncovalent backbone planarization strategy to fabricate a gas/phototheranostic nanocomposite (B-E-NO NPs) in the near-infrared-II (NIR-II, 1000-1700 nm) window by incorporating noncovalent conformational locks. B-E-NO NPs display a giant NIR-II extinction coefficient, realizing multimodal imaging-guided high-efficiency NIR-II photothermal therapy (η = 45.4%) and thermal-initiated nitric oxide combination therapy.

A Mitochondria-Targeted NIR-II Molecule Fluorophore for Precise Cancer Phototheranostics.

Subcellular organelle mitochondria are becoming a key player and a driver of cancer. Mitochondrial targeting phototheranostics has attracted increasing attention for precise cancer therapy. However, those phototheranostic systems still face great challenges, including complex and multiple components, light scattering, and insufficient therapeutic efficacy. Herein, a molecular fluorophore IR-TPP-1100 was tactfully designed by molecular engineering for mitochondria-targeted fluorescence imaging-guided phototherapy in the second near-infrared window (NIR-II). IR-TPP-1100 not only exhibited prominent photophysical properties and high photothermal conversion efficiency but also achieved excellent mitochondria-targeting ability. The mitochondria-targeting IR-TPP-1100 enabled NIR-II fluorescence and photoacoustic dual-modality imaging of mitochondria at the organism level. Moreover, it integrated photothermal and photodynamic therapy, obtaining remarkable tumor therapeutic efficacy by inducing mitochondrial apoptosis. These results indicate that IR-TPP-1100 has great potential for precise cancer therapy and provides a promising strategy for developing mitochondria-targeting NIR-II phototheranostic agents.

A biomimetic cuproptosis amplifier for targeted NIR-II fluorescence/photoacoustic imaging-guided synergistic NIR-II photothermal immunotherapy.

The therapeutic efficacy of cuproptosis combined with phototheranostics is still hindered by easy copper efflux, nonspecific accumulation and limited light penetration depth. Here, a high-performance NIR-II semiconductor polymer was first synthesized through dual-donor engineering. Then a biomimetic cuproptosis amplifier (PCD@CM) was prepared by Cu(II)-mediated coordinative self-assembly of NIR-II ultrasmall polymer dots and the chemotherapeutic drug DOX, followed by camouflaging of tumor cell membranes. After homologous targeting delivery to tumor cells, overexpressed GSH in the tumor microenvironment (TME) triggers the disassembly of the amplifier and the release of therapeutic components through the reduction of Cu(II) to Cu(I), which enable NIR-II fluorescence/photoacoustic imaging-guided NIR-II photothermal therapy (PTT) and chemotherapy. The released Cu(I) induces the aggregation of lipoylated mitochondrial proteins accompanied by the loss of iron-sulfur proteins, leading to severe proteotoxic stress and eventually cuproptosis. NIR-II PTT and GSH depletion render tumor cells more sensitive to cuproptosis. The amplified cuproptosis sensitization provokes significant immune surveillance, triggering the immunogenic cell death (ICD) to promote cytotoxic T lymphocyte infiltration together with aPD-L1-mediated immune checkpoint blockade. This work proposes a new strategy to develop cuproptosis sensitization systems enhanced by NIR-II phototheranostics with homologous targeting and anti-tumor immune response capabilities.

Phenylboronic Acid-Modified Near-Infrared Region II Excitation Donor-Acceptor-Donor Molecule for 2-Deoxy-d-Glucose Improved Starvation/Chemo/Photothermal Combination Therapy.

Synergistic chemotherapy and photothermal therapy (PTT) have emerged as a promising anticancer paradigm to achieve expected therapeutic effects while mitigating side effects. However, the chemo/PTT combination therapy suffers from limited penetration depth, thermoresistance performance of tumor cells, and low drug bioavailability. Herein, multifunctional nanoparticles (BTP/DOX/2DG NPs) coloaded with near-infrared region II (NIR-II) light excitation donor-acceptor-donor (D-A-D) small molecules, doxorubicin (DOX), and 2-deoxy-d-glucose (2-DG) are developed for reinforced starvation/chemo/NIR-II PTT combination therapy. The synthesized phenylboronic acid (PBA)-modified water-soluble D-A-D molecule (BBT-TF-PBA) not only exhibits high binding ability to DOX and 2-DG through donor-acceptor coordination interactions PBA-diol bonds but also serves as a photoactive agent for NIR-II fluorescence imaging, NIR-II photoacoustic imaging, and NIR-II PTT. Under the acidic and oxidizing conditions in the tumor microenvironment, donor-acceptor coordination interactions and PBA-diol bond are decomposed, simultaneously releasing DOX and 2-DG from BTP/DOX/2DG NPs to achieve effective chemotherapy and starvation therapy. 2-DG also effectively inhibits the expression of heat shock protein and further enhances NIR-II PTT and chemotherapy efficiency. In vitro and in vivo experiments demonstrate the combination effect of BTP/DOX/2DG NPs for chemotherapy, NIR-II PTT, and starvation therapy.

Self-delivery of metal-coordinated NIR-II nanoadjuvants for multimodal imaging-guided photothermal-chemodynamic amplified immunotherapy.

The effectiveness of phototheranostics induced immunotherapy is still hampered by limited light penetration depth, the complex immunosuppressive tumor microenvironment (TME) and the low efficiency of immunomodulator drug delivery. Herein, self-delivery and TME responsive NIR-II phototheranostic nanoadjuvants (NAs) were fabricated to suppress the growth and metastasis of melanoma through the integration of photothermal-chemodynamic therapy (PTT-CDT) and immune remodeling. The NAs were constructed by the self-assembly of ultrasmall NIR-II semiconducting polymer dots and the toll-like receptor agonist resiquimod (R848) utilizing manganese ions (Mn2+) as coordination nodes. Under acidic TME, the NAs responsively disintegrated and released therapeutic components, which enable NIR-II fluorescence/photoacoustic/magnetic resonance imaging-guided tumor PTT-CDT. Moreover, the synergistic treatment of PTT-CDT could induce significant tumor immunogenic cell death and evoke highly efficacious cancer immunosurveillance. The released R848 stimulated the maturation of dendritic cells, which both amplified the antitumor immune response by modulating and remodeling the TME. The NAs present a promising integration strategy of polymer dot-metal ion coordination and immune adjuvants for precise diagnosis and amplified anti-tumor immunotherapy against deep-seated tumors. STATEMENT OF SIGNIFICANCE: The efficiency of phototheranostics induced immunotherapy is still limited by insufficient light penetration depth, low immune response and the complex immunosuppressive tumor microenvironment (TME). In order to improve the efficacy of immunotherapy, self-delivery NIR-II phototheranostic nanoadjuvants (PMR NAs) were successfully fabricated via the facile coordination self-assembly of ultra-small NIR-II semiconducting polymer dots and toll-like receptor agonist resiquimod (R848) utilizing manganese ions (Mn2+) as coordination nodes. PMR NAs not only enable TME responsive cargo release and NIR-II fluorescence/photoacoustic/magnetic resonance imaging mediated precise localization of tumors, but also achieve synergistic photothermal-chemodynamic therapy, evoking an effective anti-tumor immune response by ICD effect. The responsively released R848 could further amplify the efficiency of immunotherapy by reversing and remodeling the immunosuppressive tumor microenvironment, thereby effectively inhibiting tumor growth and lung metastasis.

An Activatable Phototheranostic Nanoplatform for Tumor Specific NIR-II Fluorescence Imaging and Synergistic NIR-II Photothermal-Chemodynamic Therapy.

The phototheranostics in the second near-infrared window (NIR-II) have proven to be promising for the precise cancer theranostics. However, the non-responsive and "always on" imaging mode lacks the selectivity, leading to the poor diagnosis specificity. Herein, a tumor microenvironment (TME) activated NIR-II phototheranostic nanoplatform (Ag2 S-Fe(III)-DBZ Pdots, AFD NPs) is designed based on the principle of Förster resonance energy transfer (FRET). The AFD NPs are fabricated through self-assembly of Ag2 S QDs (NIR-II fluorescence probe) and ultra-small semiconductor polymer dots (DBZ Pdots, NIR-II fluorescence quencher) utilizing Fe(III) as coordination nodes. In normal tissues, the AFD NPs maintain in "off" state, due to the FRET between Ag2 S QDs and DBZ Pdots. However, the NIR-II fluorescence signal of AFD NPs can be rapidly "turn on" by the overexpressed GSH in tumor tissues, achieving a superior tumor-to-normal tissue (T/NT) signal ratio. Moreover, the released Pdots and reduced Fe(II) ions provide NIR-II photothermal therapy (PTT) and chemodynamic therapy (CDT), respectively. The GSH depletion and NIR-II PTT effect further aggravate CDT mediated oxidative damage toward tumors, achieving the synergistic anti-tumor therapeutic effect. The work provides a promising strategy for the development of TME activated NIR-II phototheranostic nanoprobes.

Increasing Molecular Planarity through Donor/Side-Chain Engineering for Improved NIR-IIa Fluorescence Imaging and NIR-II Photothermal Therapy under 1064†nm.

Developing conjugated small molecules (CSM) with intense NIR-II (1000-1700 nm) absorption for phototheranostic is highly desirable but remains a tremendous challenge due to a lack of reliable design guidelines. This study reports a high-performance NIR-II CSM for phototheranostic by tailoring molecular planarity. A series of CSM show bathochromic absorption extended to the NIR-II region upon the increasing thiophene number, but an excessive number of thiophene results in decreased NIR-IIa (1300-1400 nm) brightness and photothermal effects. Further introduction of terminal nonconjugated alkyl chain can enhance NIR-II absorption coefficient, NIR-IIa brightness, and photothermal effects. Mechanism studies ascribe this overall enhancement to molecular planarity stemming from the collective contribution of donor/side-chain engineering. This finding directs the design of NIR-II CSM by rational manipulating molecular planarity to perform 1064 nm mediated phototheranostic at high efficiency.

Molecular Oligomerization and Donor Engineering Strategies for Achieving Superior NIR-II Fluorescence Imaging and Thermotherapy under 1064 nm Laser Irradiation.

An enormous challenge still exists for designing molecules with the second near-infrared (NIR-II, 1000-1700 nm) window absorption, NIR-II fluorescence emission, and batch-to-batch reproducibility, which is the premise for high-performance NIR-II phototheranostics. Although organic small molecules and polymers have been largely explored for phototheranostics, it is difficult to satisfy the above three elements simultaneously. In this work, molecular oligomerization (the general structure is S-D-A-D'-A-D-S) and donor engineering (changing the donor linker D') strategies are applied to design phototheranostic agents. Such strategies are proved to be efficient in adjusting molecular configuration and energy level, affecting the optical and thermal properties. Three oligomers (O-T, O-DT, and O-Q) are further prepared into water-soluble nanoparticles (NPs). Particularly, the O-T NPs exhibit a higher molar extinction coefficient at 1064 nm (≈4.3-fold of O-DT NPs and ≈4.8-fold of O-Q NPs). Furthermore, the O-T NPs show the highest NIR-II fluorescence brightness and heating capacity (PCE = 73%) among the three NPs under 1064 nm laser irradiation and served as agents for NIR-II imaging guided in vivo photothermal therapy. Overall, by using molecular oligomerization and donor engineering strategies, a powerful example of constructing high-performance NIR-II phototheranostics for clinical translation is given.

Injectable Nanomedicine-Hydrogel for NIR Light Photothermal-Chemo Combination Therapy of Tumor.

Traditional hydrogels have drawbacks such as surgical implantation, large wound surfaces, and uncontrollable drug release during tumor treatment. In this paper, targeted nanomedicine has been combined with injectable hydrogel for photothermal-chemotherapy combination therapy. First, targeted nanomedicine (ICG-MTX) was fabricated by combining near-infrared (NIR) photothermal reagents (ICG) and chemotherapy drugs (MTX). The ICG-MTX was then mixed with the hydrogel precursor and radical initiator to obtain an injectable hydrogel precursor solution. Under the irradiation of NIR light, the precursor solution could release alkyl radicals, which promote the transition of the precursor solution from a liquid to a colloidal state. As a result, the nanomedicine could effectively remain at the site of the tumor and continue to be released from the hydrogel. Due to the targeted nature of MTX, the released ICG-MTX could target tumor cells and improve the accuracy of photothermal-chemo combination therapy. The results indicated that the injectable nanomedicine-hydrogel system has a favorable therapeutic effect on tumors.

Conjugated/nonconjugated alternating copolymers for enhanced NIR-II fluorescence imaging and NIR-II photothermal-ferrotherapy.

Conjugated polymers hold great promise for NIR-II fluorescence imaging (FI)-guided NIR-II photothermal therapy (PTT) due to the advantages of easy modification of chemical structures and adjustable NIR absorption. However, to make use of these advantages, it is of paramount importance to formulate conjugated polymers with excellent solubility in organic solution, great NIR-II photothermal conversion efficiency, and high NIR-II fluorescence quantum yield. Herein, a new class of conjugated/nonconjugated alternating copolymers (CNACPs) is reported by introducing nonconjugated linkers into a conjugated backbone to modulate the extinction coefficient at 1064 nm and NIR-II fluorescence quantum yield. The NIR-II absorption, NIR-II emission, and NIR-II photothermal properties of the new CNACPs were studied. Interestingly, it is observed that longer nonconjugated linkers in CNACPs result in higher NIR-II fluorescence intensity with sufficient NIR-II absorption and NIR-II photothermal ability. With these newly developed CNACPs (BBT-C6), phototheranostic nanoparticles (BBTD6/Fe@PMA) are prepared through facile nanoprecipitation using PMA-AD-PEG as an iron ion chelator for NIR-II FI-guided NIR-II PTT/ferrotherapy synergistic therapy. In vitro and in vivo, BBTD6/Fe@PMA effectively inhibited 4T1 cells and tumor progression under 1064 nm laser irradiation. Consequently, this work provides new CNACPs by incorporating nonconjugated linkers into a conjugated backbone to design more effective NIR-II fluorescence imaging and NIR-II photothermal therapy agents.

NIR-II Excitation Phototheranostic Platform for Synergistic Photothermal Therapy/Chemotherapy/Chemodynamic Therapy of Breast Cancer Bone Metastases.

To improve bone metastases treatment efficacy, current strategies are focused on the integration of chemotherapy with phototheranostic. However, the success of phototheranostic approaches is hampered by the limited tissue penetration depth of near-infrared-I (NIR-I) light (700-900 nm). In this study, a NIR-II (1000-1700 nm) excitation phototheranostic (BTZ/Fe2+ @BTF/ALD) is presented for NIR-II fluorescence imaging and NIR-II photoacoustic imaging-guided NIR-II photothermal therapy (PTT), chemotherapy, and chemodynamic therapy (CDT) of breast cancer bone metastases. This phototheranostic is developed by integrating a dopamine-modified NIR-II absorbing donor-acceptor-donor small molecule (BBT-FT-DA), the boronate anticancer drug bortezomib (BTZ), and Fe2+ ions, as CDT catalysts, into an amphiphilic PEGylated phospholipid modified with the bone-targeting ligand alendronate. In acidic and hydrogen peroxide (H2 O2 ) over expression tumor microenvironment, the boronate-catechol linkage is cleaved and BTZ and Fe2+ ions are released to initiate the Fenton reaction, that is, chemotherapy and CDT, respectively, are initialized. It is confirmed using the murine 4T1 bone metastasis model that BTZ/Fe2+ @BTF/ALD significantly suppresses the progression of tumor cells in the bone tissue via a synergistic NIR-II PTT/chemotherapy/CDT effect. Overall, this work provides fresh insights to guide the development of NIR-II phototheranostics for breast cancer bone metastases.

Anisotropic plasmonic Pd-tipped Au nanorods for near-infrared light-activated photoacoustic imaging guided photothermal-photodynamic cancer therapy.

The integration of photothermal therapy (PTT) and photodynamic therapy (PDT) has become a promising cancer treatment method. Herein, anisotropic metal hetero-nanostructure Pd-tipped Au nanorods (PTA NRs) were fabricated, which exhibit plasmon-enhanced photothermal performance under near-infrared laser irradiation. Due to their anisotropic nanostructure, PTA NRs promote the generation of energetic hot electrons and prolong the separation time of electrons and holes. The hot electrons could generate heat energy through the electron-phonon relaxation process and produce reactive oxygen species through energy and electron transformation processes. Because of their high NIR absorption cross-section, as well as good photostability, PTA NRs can be used for NIR-activated photoacoustic imaging-guided PTT-PDT combination cancer therapy. Experiments in tumor-bearing mice proved that PTA NRs exhibit excellent anti-tumor effects, with little side effects on normal organs, making them promising for NIR cancer phototherapy.

Near-infrared-II light excitation thermosensitive liposomes for photoacoustic imaging-guided enhanced photothermal-chemo synergistic tumor therapy.

Despite the great success of photothermal therapy (PTT), it still suffers from many obstacles, such as the limited penetration depth of light, thermoresistance of tumors, and limitations of mono-therapeutic modalities. Herein, second near-infrared (NIR-II, 1064 nm) light excitation thermosensitive liposomes (DG@TLs) were fabricated for photoacoustic imaging (PAI) guided enhanced PTT-chemotherapy. DG@TLs were constructed by encapsulating NIR-II light excitation semiconducting polymers into liposomes composed of phase change materials (PCMs), along with gambogic acid (GA) with chemotherapeutic and heat shock protein inhibition effects. Under 1064 nm laser irradiation, DG@TLs exhibited superior NIR-II PAI and PTT performances with deep tissue penetration while triggering the thermoresponsive release of GA based on the phase transition of PCMs from solid to liquid. The released GA could enhance the NIR-II PTT efficacy by inhibiting the activity of HSP90, reducing the thermoresistance of tumors, exhibiting significant chemotherapeutic effects, and achieving synergistic anti-tumor efficiency. This work provides a new strategy for achieving on-demand drug release and effective theranostics in deep-seated tumor regions.

NIR-II Excitation Phototheranostic Nanomedicine for Fluorescence/Photoacoustic Tumor Imaging and Targeted Photothermal-Photonic Thermodynamic Therapy.

The success of phototheranostics is hampered by some intrinsic defects, such as limited light penetration depth, heat resistance of tumor cells to photothermal therapy (PTT) induced by heat shock protein (HSP) and stress resistance against photodynamic therapy (PDT) caused by hypoxia microenvironment of tumor. Herein, a second near infrared (NIR-II) light excitation phototheranostic nanomedicine has been fabricated by integrating the semiconducting polymer, azo compound, and HSP inhibitor into a thermosensitive liposome, followed by modification with targeting aptamer, forming Lip(PTQ/GA/AIPH) for multimodal phototheranostics of triple-negative breast cancer (TNBC). The phototheranostic nanomedicine provides tumor targeting NIR-II fluorescence and photoacoustic dual-modal imaging, as well as NIR-II PTT. The released HSP inhibitor can effectively inhibit the activity of HSP for enhanced NIR-II PTT. Moreover, azo compound can be decomposed by the NIR-II photothermal activation, generating cytotoxic free radicals and realizing oxygen-irrelevant photonic thermodynamic therapy (PTDT) effects. Under the NIR-II laser irradiation, NIR-II fluorescence/photoacoustic dual-modal imaging guided enhanced NIR-II PTT and PTDT by Lip(PTQ/GA/AIPH), can achieve precise diagnosis and effective suppression of deep-seated TNBC with negligible side effects. This work develops a promising NIR-II excitation phototheranostic nanomedicine for spatiotemporally specific diagnosis and combination therapy of TNBC.

NIR-II fluorescence imaging guided tumor-specific NIR-II photothermal therapy enhanced by starvation mediated thermal sensitization strategy.

Photothermal therapy (PTT) is hampered by limited light penetration depth and cell thermoresistance induced by over-expressed heat shock proteins (HSPs). Herein, we proposed a tumor-specific enhanced NIR-II PTT through the starvation mediated thermal sensitization strategy. A semiconducting polymer with superior NIR-II fluorescence imaging (FI) performance and NIR-II PTT efficacy was synthesized and encapsulated into folate modified liposomes, together with a glycolysis inhibitor, 2-deoxy-d-glucose (2DG). Upon specifically targeting folate receptors and guidance of NIR-II FI, spatiotemporal 2DG release could be achieved by the trigger of NIR-II photothermal effect. The released 2DG could not only deplete the energy supply of tumor cells by inhibiting tumor anaerobic glycolysis, but also decrease the ATP levels and hamper the production of HSPs, ultimately enhancing the tumor thermal sensitivity toward PTT. Owing to the sensitization effect of 2DG, tumor cells with overexpressed folate receptors could be significantly damaged by NIR-II PTT with an enhanced therapeutic efficiency. The work provided a promising strategy for specific starvation/NIR-II PTT synergistic therapy towards tumors.

Injectable and Thermosensitive Liposomal Hydrogels for NIR-II Light-Triggered Photothermal-Chemo Therapy of Pancreatic Cancer.

An injectable hydrogel sustained drug release system could be a promising technique for in situ treatment. Herein, an injectable hydrogel was prepared for photothermal-chemo therapy of cancer based on the thermosensitive liposomal hydrogel (Lip-Gel). The Lip-Gel system was fabricated by encapsulation of the NIR-II photothermal agent (DPP-BTz) and chemotherapy drugs (GEM) in thermosensitive liposomes and then combined with hydrogel precursor solution. The hydrogel precursor was used as an injectable flowing solution at room temperature and transferred into a cross-linked gel structure at physiological temperature. After being injected into the tumor, DPP-BTz in the Lip-Gel system can generate heat under irradiation of 1064 nm laser, breaking the thermosensitive liposomes and releasing GEM to kill tumor cells. From the treatment results, the Lip-Gel system showed a significant antitumor effect through chemo-/photothermal therapy combination therapy triggered by the NIR-II laser. This work provides a useful scheme for the development of drug delivery and drug treatment directions for local cancer therapy.

Tunable NIR Absorption Property of a Dithiolene Nickel Complex: A Promising NIR-II Absorption Material for Photothermal Therapy.

Exogenous photothermal agents absorbing in the second near-infrared optical window (NIR-II, 1000-1700 nm) have received much attention due to their use in noninvasive photothermal therapy. A small quantity of organic NIR-II photothermal agents have been exploited, and the development of organic NIR-II photothermal materials is an urgent need for biological applications. In this study, we designed and synthesized three dithiolene nickel(II) complexes with different ligands-bis(phenyl) dithiolene for NiBD-Ph, bis(fluorenyl) dithiolene for NiBD-Fl, and bis(carbazolyl) dithiolene for NiBD-Cz-and investigated their photophysical properties. These complexes exhibited ligand-dependent NIR absorption performance, centered at 854 nm for NiBD-Ph, 942 nm for NiBD-Fl, and 1010 nm for NiBD-Cz, respectively. NiBD-Cz is wrapped in ethylene oxide/propylene oxide block copolymer (F-127) through a hydrophilic-hydrophobic interaction to form water-soluble NiBD-Cz/F-127 nanoparticles (NiBD-Cz NPs), and the absorption peak of NiBD-Cz NPs are red-shifted to 1036 nm. NiBD-Cz NPs exhibit good dispersibility in water, robust photostability, and a high photothermal conversion efficiency (PCE) of 63.6% under 1064 nm laser irradiation, which is the highest PCE among metal bis(dithiolene) complexes up to now. The high PCE makes it possible to achieve better photothermal treatment effects even at low concentrations and under low-power laser irradiation.

Ionic liquid induced highly dense assembly of porphyrin in MOF nanosheets for photodynamic therapy.

Two-dimensional (2D) metal-organic framework (MOF) nanosheets have emerged as a new member of 2D nanomaterials for molecular sieving, energy conversion and storage, catalysis and biomedicine. In this paper, a highly dense assembly of porphyrin achievable in porphyrin-integrated MOF nanosheets induced by an ionic liquid is obtained by sonication exfoliation of its bulk crystals. The 2D layered structure MOF, [BMI]2[Ca3(H2TCPP)2(µ2-OH2)2(H2O)2] (1), was firstly prepared by using the ionic liquid assisted synthetic method (H6TCPP = meso-tetra(carboxyphenyl) porphyrin, BMI = 1-butyl-3-methylimidazolium). The laminated layers in 1 clearly indicate a weak interlayer non-covalent interaction but a strong metal-carboxylate bonding within the layers, which facilitates the exfoliation of 1 to form 2D MOF nanosheets (1 NSs). Powder X-ray diffraction (PXRD), high-resolution transmission electron microscopy (HR-TEM) and fast Fourier transform (FFT) patterns revealed that 1 NSs could maintain their crystalline structure after exfoliation. These MOF nanosheets exhibited excellent aqueous dispersibility, biodegradability and high cytotoxicity under light irradiation against MCF-7 cells.