UV–Vis–NIR Full‐Range Responsive Carbon Dots with Large Multiphoton Absorption Cross Sections and Deep‐Red Fluorescence at Nucleoli and In Vivo

Carbon dots (CDs), with excellent optical property and cytocompatibility, are an ideal class of nanomaterials applied in the field of biomedicine. However, the weak response of CDs in the near‐infrared (NIR) region impedes their practical applications. Here, UV–vis–NIR full‐range responsive fluorine and nitrogen doped CDs (N‐CDs‐F) are designed and synthesized that own a favorable donor‐π‐acceptor (D‐π‐A) configuration and exhibit excellent two‐photon (λ_ex = 1060 nm), three‐photon (λ_ex = 1600 nm), and four‐photon (λ_ex = 2000 nm) excitation upconversion fluorescence. D‐π‐A‐conjugated CDs prepared by solvothermal synthesis under the assistance of ammonia fluoride are reported and are endowed with larger multiphoton absorption (MPA) cross sections (3PA: 9.55 × 10^?80 cm⁶ s² photon^?2, 4PA: 6.32 × 10^?80 cm⁸ s³ photon^?3) than conventional organic compounds. Furthermore, the N‐CDs‐F show bright deep‐red to NIR fluorescence both in vitro and in vivo, and can even stain the nucleoli of tumor cells. A plausible mechanism is proposed on the basis of the strong inter‐dot and intra‐dot hydrogen bonds through N? H···F that can facilitate the expanding of conjugated sp² domains, and thus not only result in lower highest occupied molecular orbital‐lowest unoccupied molecular orbital energy level but also larger MPA cross sections than those of undoped CDs.     

Precise Two‐Photon Photodynamic Therapy using an Efficient Photosensitizer with Aggregation‐Induced Emission Characteristics

Two‐photon photodynamic therapy (PDT) is able to offer precise 3D manipulation of treatment volumes, providing a target level that is unattainable with current therapeutic techniques. The advancement of this technique is greatly hampered by the availability of photosensitizers with large two‐photon absorption (TPA) cross section, high reactive‐oxygen‐species (ROS) generation efficiency, and bright two‐photon fluorescence. Here, an effective photosensitizer with aggregation‐induced emission (AIE) characteristics is synthesized, characterized, and encapsulated into an amphiphilic block copolymer to form organic dots for two‐photon PDT applications. The AIE dots possess large TPA cross section, high ROS generation efficiency, and excellent photostability and biocompatibility, which overcomes the limitations of many conventional two‐photon photosensitizers. Outstanding therapeutic performance of the AIE dots in two‐photon PDT is demonstrated using in vitro cancer cell ablation and in vivo brain‐blood‐vessel closure as examples. This shows therapy precision up to 5 µm under two‐photon excitation.     

Lipid‐PEG‐Folate Encapsulated Nanoparticles with Aggregation Induced Emission Characteristics: Cellular Uptake Mechanism and Two‐Photon Fluorescence Imaging

Folate functionalized nanoparticles (NPs) that contain fluorogens with aggregation‐induced emission (AIE) characteristics are fabricated to show bright far‐red/near‐infrared fluorescence, a large two‐photon absorption cross section and low cytotoxicity, which are internalized into MCF‐7 cancer cells mainly through caveolae‐mediated endocytosis. One‐photon excited in vivo fluorescence imaging illustrates that these AIE NPs can accumulate in a tumor and two‐photon excited ex vivo tumor tissue imaging reveals that they can be easily detected in the tumor mass at a depth of 400 μm. These studies indicate that AIE NPs are promising alternatives to conventional TPA probes for biological imaging.     

NIR‐II‐Excited Intravital Two‐Photon Microscopy Distinguishes Deep Cerebral and Tumor Vasculatures with an Ultrabright NIR‐I AIE Luminogen

Intravital fluorescence imaging of vasculature morphology and dynamics in the brain and in tumors with large penetration depth and high signal‐to‐background ratio (SBR) is highly desirable for the study and theranostics of vascular‐related diseases and cancers. Herein, a highly bright fluorophore (BTPETQ) with long‐wavelength absorption and aggregation‐induced near‐infrared (NIR) emission (maximum at ≈700 nm) is designed for intravital two‐photon fluorescence (2PF) imaging of a mouse brain and tumor vasculatures under NIR‐II light (1200 nm) excitation. BTPETQ dots fabricated via nanoprecipitation show uniform size of around 42 nm and a high quantum yield of 19 ± 1% in aqueous media. The 2PF imaging of the mouse brain vasculatures labeled by BTPETQ dots reveals a 3D blood vessel network with an ultradeep depth of 924 µm. In addition, BTPETQ dots show enhanced 2PF in tumor vasculatures due to their unique leaky structures, which facilitates the differentiation of normal blood vessels from tumor vessels with high SBR in deep tumor tissues. Moreover, the extravasation and accumulation of BTPETQ dots in deep tumor (more than 900 µm) is visualized under NIR‐II excitation. This study highlights the importance of developing NIR‐II light excitable efficient NIR fluorophores for in vivo deep tissue and high contrast tumor imaging.     

One‐Step Hydrothermal Synthesis of Nitrogen‐Doped Conjugated Carbonized Polymer Dots with 31% Efficient Red Emission for In Vivo Imaging

Carbon dots with long‐wavelength emissions, high quantum yield (QY) and good biocompatibility are highly desirable for biomedical applications. Herein, a green, facile hydrothermal synthesis of highly efficient red emissive nitrogen‐doped carbonized polymer dots (CPDs) with optimal emission at around 630 nm are reported. The red emissive CPDs possess a variety of superior properties including excellent water dispersibility, good biocompatibility, narrow bandwidth emission, an excitation‐independent emission, and high QY (10.83% (in water) and 31.54% (in ethanol)). Further studies prove that such strong red fluorescence is ascribed to the efficient conjugated aromatic π systems and hydrogen bonds of CPDs. And the fluorescence properties of CPDs can be regulated by adjusting the dosage of HNO₃ before the reaction. Additionally, the as‐prepared CPDs are successfully used as a fluorescent probe for bioimaging, both in vitro and in vivo. More importantly, biodistribution results demonstrate that most CPDs and their metabolites are not only excreted in urine but also excreted by hepatobiliary system in a rapid manner. Besides, the CPDs could easily cross the blood brain barrier, which may provide a valuable strategy for the theranostics of some brain diseases through real‐time tracking.     

2D Perovskites with Giant Excitonic Optical Nonlinearities for High‐Performance Sub‐Bandgap Photodetection

Two‐dimensional (2D) perovskites have proved to be promising semiconductors for photovoltaics, photonics, and optoelectronics. Here, a strategy is presented toward the realization of highly efficient, sub‐bandgap photodetection by employing excitonic effects in 2D Ruddlesden–Popper‐type halide perovskites (RPPs). On near resonance with 2D excitons, layered RPPs exhibit degenerate two‐photon absorption (D‐2PA) coefficients as giant as 0.2–0.64 cm MW^?1. 2D RPP‐based sub‐bandgap photodetectors show excellent detection performance in the near‐infrared (NIR): a two‐photon‐generated current responsivity up to 1.2 × 10⁴ cm² W^?2 s^?1, two orders of magnitude greater than InAsSbP‐pin photodiodes; and a dark current as low as 2 pA at room temperature. More intriguingly, layered‐RPP detectors are highly sensitive to the light polarization of incoming photons, showing a considerable anisotropy in their D‐2PA coefficients (β_[001]/β_[011] = 2.4, 70% larger than the ratios reported for zinc‐blende semiconductors). By controlling the thickness of the inorganic quantum well, it is found that layered RPPs of (C₄H₉NH₃)₂(CH₃NH₃)Pb₂I₇ can be utilized for three‐photon photodetection in the NIR region.     

Low‐Saturation‐Intensity,High‐Photostability,and High‐Resolution STED Nanoscopy Assisted by CsPbBr3 Quantum Dots

Stimulated emission depletion (STED) nanoscopy is one of the most promising super‐resolution imaging techniques for microstructure imaging. Commercial CdSe@ZnS quantum dots are used as STED probes and ≈50 nm lateral resolution is obtained. Compared with other quantum dots, perovskite CsPbBr₃ nanoparticles (NPs) possess higher photoluminescence quantum yield and larger absorption cross‐section, making them a more effective probe for STED nanoscopy. In this study, CsPbBr₃ NPs are used as probes for STED nanoscopy imaging. The fluorescence intensity of the CsPbBr₃ sample is hardly weakened at all after 200 min irradiation with a 39.8 mW depletion laser, indicating excellent photobleaching resistance of the CsPbBr₃ NPs. The saturation intensity of the CsPbBr₃ NPs is extremely low and estimated to be only 0.4 mW (0.126 MW cm^?2). Finally, an ultrahigh lateral resolution of 20.6 nm is obtained for a single nanoparticle under 27.5 mW STED laser irradiation in CsPbBr₃‐based STED nanoscopy imaging, which is a tenfold improvement compared with confocal microscopy. Because of its high fluorescence stability and ultrahigh resolution under lower depletion power, CsPbBr₃‐assisted STED nanoscopy has great potential to investigate microstructures that require super‐resolution and long‐term imaging.     

Highly Solid‐State Emissive Pyridinium‐Substituted Tetraphenylethylene Salts: Emission Color‐Tuning with Counter Anions and Application for Optical Waveguides

In this paper seven salts of pyridinium‐substituted tetraphenylethylene with different anions are reported. They show typical aggregation‐induced emission. Crystal structures of three of the salts with (CF₃SO₂)₂N^?, CF₃SO₃ ^?, and SbF₆ ^? as the respective counter anions, are determined. The emission behavior of their amorphous and crystalline solids is investigated. Both amorphous and crystalline solids, except for the one with I^?, are highly emissive. Certain amorphous solids are red‐emissive with almost the same quantum yields and fluorescence life‐times. However, some crystalline solids are found to show different emission colors varying from green to yellow. Thus, their emission colors can be tuned by the counter anions. Furthermore, certain crystalline solids are highly emissive compared to the respective amorphous solids. Such solid‐state emission behavior of these pyridinium‐substituted tetraphenylethylene salts is interpreted on the basis of their crystal structures. In addition, optical waveguiding behavior of fabricated microrods is presented.     

Magneto‐Photoluminescence Based on Two‐Photon Excitation in Lanthanide‐Doped Up‐Conversion Crystal Particles

Experimental studies on magneto‐photoluminescence based on two‐photon excitation in up‐conversion Y₂O₂S:Er, Yb crystal particles are reported. It is found that the up‐conversion photoluminescence generated by two‐photon excitation exhibits magnetic field effects at room temperature, leading to a two‐photon excitation‐induced magneto‐photoluminescence, when the two‐photon excitation exceeds the critical intensity. By considering the spin selection rule in electronic transitions, it is proposed that spin‐antiparallel and spin‐parallel transition dipoles with spin mixing are accountable for the observed magneto‐photoluminescence. Specifically, the two‐photon excitation generates spin‐antiparallel electric dipoles between ⁴S_3/2–⁴I_15/2 in Er³⁺ ions. The antiparallel spins are conserved by exchange interaction within dipoles. When the photoexcitation exceeds the critical intensity, the Coulomb screening can decrease the exchange interaction. Consequently, the spin–orbital coupling can partially convert the antiparallel dipoles into parallel dipoles, generating a spin mixing. Eventually, the populations between antiparallel and parallel dipoles reach an equilibrium established by the competition between exchange interaction and spin–orbital coupling. Applying a magnetic field can break the equilibrium by disturbing spin mixing through introducing spin precessions, changing the spin populations on antiparallel and parallel dipoles and leading to the magneto‐photoluminescence. Therefore, spin‐dependent transition dipoles present a convenient mechanism to realize magneto‐photoluminescence in multiphoton up‐conversion crystal particles.     

A Highly Efficient and Photostable Photosensitizer with Near‐Infrared Aggregation‐Induced Emission for Image‐Guided Photodynamic Anticancer Therapy

Photodynamic therapy (PDT), which relies on photosensitizers (PS) and light to generate reactive oxygen species to kill cancer cells or bacteria, has attracted much attention in recent years. PSs with both bright emission and efficient singlet oxygen generation have also been used for image‐guided PDT. However, simultaneously achieving effective ¹O₂ generation, long wavelength absorption, and stable near‐infrared (NIR) emission with low dark toxicity in a single PS remains challenging. In addition, it is well known that when traditional PSs are made into nanoparticles, they encounter quenched fluorescence and reduced ¹O₂ production. In this contribution, these challenging issues have been successfully addressed through designing the first photostable photosensitizer with aggregation‐induced NIR emission and very effective ¹O₂ generation in aggregate state. The yielded nanoparticles show very effective ¹O₂ generation, bright NIR fluorescence centered at 820 nm, excellent photostability, good biocompatibility, and negligible dark in vivo toxicity. Both in vitro and in vivo experiments prove that the nanoparticles are excellent candidates for image‐guided photodynamic anticancer therapy.     

Bright Aggregation‐Induced‐Emission Dots for Targeted Synergetic NIR‐II Fluorescence and NIR‐I Photoacoustic Imaging of Orthotopic Brain Tumors

Precise diagnostics are of significant importance to the optimal treatment outcomes of patients bearing brain tumors. NIR‐II fluorescence imaging holds great promise for brain‐tumor diagnostics with deep penetration and high sensitivity. This requires the development of organic NIR‐II fluorescent agents with high quantum yield (QY), which is difficult to achieve. Herein, the design and synthesis of a new NIR‐II fluorescent molecule with aggregation‐induced‐emission (AIE) characteristics is reported for orthotopic brain‐tumor imaging. Encapsulation of the molecule in a polymer matrix yields AIE dots showing a very high QY of 6.2% with a large absorptivity of 10.2 L g^?1 cm^?1 at 740 nm and an emission maximum near 1000 nm. Further decoration of the AIE dots with c‐RGD yields targeted AIE dots, which afford specific and selective tumor uptake, with a high signal/background ratio of 4.4 and resolution up to 38 µm. The large NIR absorptivity of the AIE dots facilitates NIR‐I photoacoustic imaging with intrinsically deeper penetration than NIR‐II fluorescence imaging and, more importantly, precise tumor‐depth detection through intact scalp and skull. This research demonstrates the promise of NIR‐II AIE molecules and their dots in dual NIR‐II fluorescence and NIR‐I photoacoustic imaging for precise brain cancer diagnostics.     

Novel Mn3[Co(CN)6]2@SiO2@Ag Core–Shell Nanocube: Enhanced Two‐Photon Fluorescence and Magnetic Resonance Dual‐Modal Imaging‐Guided Photothermal and Chemo‐therapy

The versatile Mn₃[Co(CN)₆]₂@SiO₂@Ag core–shell NCs are prepared by a simple coprecipitation method. Ag nanoparticles with an average diameter of 12 nm deposited on the surface of Mn₃[Co(CN)₆]₂@SiO₂ through S–Ag bonding are fabricated in ethanol solution by reducing silver nitrate (AgNO₃) with NaBH₄. The NCs possess T₁–T₂ dual‐modal magnetic resonance imaging ability. The inner Prussian blue analogs (PBAs) Mn₃[Co(CN)₆]₂ exhibit bright two‐photon fluorescence (TPF) imaging when excited at 730 nm. Moreover, the TPF imaging intensity displays 1.85‐fold enhancement after loading of Ag nanoparticles. Besides, the sample also has multicolor fluorescence imaging ability under 403, 488, and 543 nm single photon excitation. The as‐synthesized Mn₃[Co(CN)₆]₂@SiO₂@Ag NCs show a DOX loading capacity of 600 mg g⁻¹ and exhibit an excellent ability of near‐infrared (NIR)‐responsive drug release and photothermal therapy (PTT) which is induced from the relative high absorbance in NIR region. The combined chemotherapy and PTT against cancer cells in vitro test shows high therapeutic efficiency. The multimodal treatment and imaging could lead to this material a potential multifunctional system for biomedical diagnosis and therapy.     

Tetraphenylethylene‐Interweaving Conjugated Macrocycle Polymer Materials as Two‐Photon Fluorescence Sensors for Metal Ions and Organic Molecules

A luminescent conjugated macrocycle polymer (CMP) with strong two‐photon fluorescence property, namely, P[5]‐TPE‐CMP, is constructed from ditriflate‐functionalized pillar[5]arene and a 1,1,2,2‐tetrakis(4‐ethynylphenyl)ethylene (TPE) linker through a Sonogashira–Hagihara cross‐coupling reaction. Significantly, in sharp contrast with the corresponding conjugated microporous polymer without synthetic macrocycles, P[5]‐TPE‐CMP shows an outstanding stability against photobleaching and exhibits highly selective cation sensing capability toward Fe³⁺ at different excitation wavelengths (both UV and red–near‐infrared regions). Meanwhile, its fluorescence could also be sufficiently quenched by 4‐amino azobenzene, a frequently used organic dye that is certified to be carcinogenic, as compared with a group of common organic compounds. This work paves a new way for enhancing the properties of porous organic polymers through the introduction of supramolecular macrocycles like macrocyclic arenes.     

Bright Far‐Red/Near‐Infrared Conjugated Polymer Nanoparticles for In Vivo Bioimaging

A highly emissive far‐red/near‐infrared (FR/NIR) fluorescent conjugated polymer (CP), poly[(9,9‐dihexylfluorene)‐co‐2,1,3‐benzothiadiazole‐co‐4,7‐di(thiophen‐2‐yl)‐2,1,3‐benzothiadiazole] (PFBTDBT10) is designed and synthesized via Suzuki polymerization. Formulation of PFBTDBT10 using 1,2‐distearoyl‐sn‐glycero‐3‐phosphoethanolamine‐N‐[methoxy(polyethylene glycol)‐2000] (DSPE‐PEG₂₀₀₀) and DSPE‐PEG₅₀₀₀‐folate as the encapsulation matrix yielded CP‐loaded DSPE‐PEG‐folic acid nanoparticles (CPDP‐FA NPs) with bright FR/NIR fluorescence (27% quantum yield) and a large Stoke's shift of 233 nm in aqueous solution. CPDP‐FA NPs show improved thermal/photostabilities and larger Stoke's shifts as compared to commercially available quantum dots (Qdot 655) and organic dyes such as Alexa Fluor 555 and Rhodamine 6G. In vivo studies of CPDP‐FA NPs on a hepatoma H22 tumor‐bearing mouse model reveal that they could serve as an efficient FR/NIR fluorescent probe for targeted in vivo fluorescence imaging and cancer detection in a high contrast and specific manner. Together with the negligible in vivo toxicity, CPDP‐FA NPs are promising FR/NIR fluorescent probes for future in vivo applications.     

Near‐Infrared Excitation/Emission and Multiphoton‐Induced Fluorescence of Carbon Dots

Carbon dots (CDs) have significant potential for use in various fields including biomedicine, bioimaging, and optoelectronics. However, inefficient excitation and emission of CDs in both near‐infrared (NIR‐I and NIR‐II) windows remains an issue. Solving this problem would yield significant improvement in the tissue‐penetration depth for in vivo bioimaging with CDs. Here, an NIR absorption band and enhanced NIR fluorescence are both realized through the surface engineering of CDs, exploiting electron‐acceptor groups, namely molecules or polymers rich in sulfoxide/carbonyl groups. These groups, which are bound to the outer layers and the edges of the CDs, influence the optical bandgap and promote electron transitions under NIR excitation. NIR‐imaging information encryption and in vivo NIR fluorescence imaging of the stomach of a living mouse using CDs modified with poly(vinylpyrrolidone) in aqueous solution are demonstrated. In addition, excitation by a 1400 nm femtosecond laser yields simultaneous two‐photon‐induced NIR emission and three‐photon‐induced red emission of CDs in dimethyl sulfoxide. This study represents the realization of both NIR‐I excitation and emission as well as two‐photon‐ and three‐photon‐induced fluorescence of CDs excited in an NIR‐II window, and provides a rational design approach for construction and clinical applications of CD‐based NIR imaging agents.     

Mitochondrion‐Anchoring Photosensitizer with Aggregation‐Induced Emission Characteristics Synergistically Boosts the Radiosensitivity of Cancer Cells to Ionizing Radiation

The first mitochondrion‐anchoring photosensitizer that specifically generates singlet oxygen (¹O₂) in mitochondria under white light irradiation that can serve as a highly effective radiosensitizer is reported here, significantly sensitizing cancer cells to ionizing radiation. An aggregation‐induced emission luminogen (AIEgen), namely DPA‐SCP, is rationally designed with α‐cyanostilbene as a simple building block to reveal AIE, diphenylamino (DPA) group as a strong electron donating group to benefit red emission and efficient light‐controlled ¹O₂ generation, as well as a pyridinium salt as the targeting moiety to ensure specific mitochondrial localization. The AIE signature endows DPA‐SCP with the capacity to visualize mitochondria in a fluorescence turn‐on mode. It is found that under optimized experimental condition, DPA‐SCP with white light does not lead to apoptosis/death of cancer cells, whereas provides an elevated ¹O₂ environment in the mitochondria. More importantly, increasing intracellular level of ¹O₂ originated from mitochondria is demonstrated to be a generic method to enhance the radiosensitivity of cancer cells with a supra‐additive synergistic effect of “0 + 1 > 1.” Noteworthy is that “DPA‐SCP + white light” achieves a high SER10 value of 1.62, which is much larger than that of the most popularly used radiosensitizers, gold nanoparticles (1.19), and paclitaxel (1.32).     

Two‐Photon Up‐Conversion Photoluminescence Realized through Spatially Extended Gap States in Quasi‐2D Perovskite Films

A new approach to generate a two‐photon up‐conversion photoluminescence (PL) by directly exciting the gap states with continuous‐wave (CW) infrared photoexcitation in solution‐processing quasi‐2D perovskite films [(PEA)₂(MA)₄Pb₅Br₁₆ with n = 5] is reported. Specifically, a visible PL peaked at 520 nm is observed with the quadratic power dependence by exciting the gap states with CW 980 nm laser excitation, indicating a two‐photon up‐conversion PL occurring in quasi‐2D perovskite films. Decreasing the gap states by reducing the n value leads to a dramatic decrease in the two‐photon up‐conversion PL signal. This confirms that the gap states are indeed responsible for generating the two‐photon up‐conversion PL in quasi‐2D perovskites. Furthermore, mechanical scratching indicates that the different‐n‐value nanoplates are essentially uniformly formed in the quasi‐2D perovskite films toward generating multi‐photon up‐conversion light emission. More importantly, the two‐photon up‐conversion PL is found to be sensitive to an external magnetic field, indicating that the gap states are essentially formed as spatially extended states ready for multi‐photon excitation. Polarization‐dependent up‐conversion PL studies reveal that the gap states experience the orbit–orbit interaction through Coulomb polarization to form spatially extended states toward developing multi‐photon up‐conversion light emission in quasi‐2D perovskites.     

Tumor Microenvironment‐Triggered Aggregation of Antiphagocytosis 99mTc‐Labeled Fe3O4 Nanoprobes for Enhanced Tumor Imaging In Vivo

A tumor microenvironment responsive nanoprobe is developed for enhanced tumor imaging through in situ crosslinking of the Fe₃O₄ nanoparticles modified with a responsive peptide sequence in which a tumor‐specific Arg‐Gly‐Asp peptide for tumor targeting and a self‐peptide as a “mark of self” are linked through a disulfide bond. Positioning the self‐peptide at the outmost layer is aimed at delaying the clearance of the nanoparticles from the bloodstream. After the self‐peptide is cleaved by glutathione within tumor microenvironment, the exposed thiol groups react with the remaining maleimide moieties from adjacent particles to crosslink the particles in situ. Both in vitro and in vivo experiments demonstrate that the aggregation substantially improves the magnetic resonance imaging (MRI) contrast enhancement performance of Fe₃O₄ particles. By labeling the responsive particle probe with ^99mTc, single‐photon emission computed tomography is enabled not only for verifying the enhanced imaging capacity of the crosslinked Fe₃O₄ particles, but also for achieving sensitive dual modality imaging of tumors in vivo. The novelty of the current probe lies in the combination of tumor microenvironment‐triggered aggregation of Fe₃O₄ nanoparticles for boosting the T₂ MRI effect, with antiphagocytosis surface coating, active targeting, and dual‐modality imaging, which is never reported before.     

Ultrasensitive Surface‐Enhanced Raman Spectroscopy Detection Based on Amorphous Molybdenum Oxide Quantum Dots

Surface‐enhanced Raman spectroscopy (SERS) based on plasmonic semiconductive material has been proved to be an efficient tool to detect trace of substances, while the relatively weak plasmon resonance compared with noble metal materials restricts its practical application. Herein, for the first time a facile method to fabricate amorphous H_xMoO₃ quantum dots with tunable plasmon resonance is developed by a controlled oxidization route. The as‐prepared amorphous H_xMoO₃ quantum dots show tunable plasmon resonance in the region of visible and near‐infrared light. Moreover, the tunability induced by SC CO₂ is analyzed by a molecule kinetic theory combined with a molecular thermodynamic model. More importantly, the ultrahigh enhancement factor of amorphous H_xMoO₃ quantum dots detecting on methyl blue can be up to 9.5 × 10⁵ with expending the limit of detection to 10^?9 m . Such a remarkable porperty can also be found in this H_xMoO₃‐based sensor with Rh6G and RhB as probe molecules, suggesting that the amorphous H_xMoO₃ quantum dot is an efficient candidate for SERS on molecule detection in high precision.     

Corannulene‐Incorporated AIE Nanodots with Highly Suppressed Nonradiative Decay for Boosted Cancer Phototheranostics In Vivo

Fluorescent nanoparticles (NPs) based on luminogens with aggregation‐induced emission characteristic (AIEgens), namely AIE dots, have received wide attention because of their antiquenching attitude in emission and reactive oxygen species (ROS) generation when aggregated. However, few reports are available on how to control and optimize their fluorescence and ROS generation ability. Herein, it is reported that enhancing the intraparticle confined microenvironment is an effective approach to advanced AIE dots, permitting boosted cancer phototheranostics in vivo. Formulation of a “rotor‐rich” and inherently charged near‐infrared (NIR) AIEgen with 1,2‐distearoyl‐sn‐glycero‐3‐phosphoethanolamine‐N‐[methoxy(polyethylene glycol)‐2000] and corannulene‐decorated PEG affords DSPE‐AIE dots and Cor‐AIE dots, respectively. Compared to DSPE‐AIE dots, Cor‐AIE dots show 4.0‐fold amplified fluorescence quantum yield and 5.4‐fold enhanced ROS production, because corannulene provides intraparticle rigidity and strong interactions with the AIEgen to restrict the intramolecular rotation of AIEgen to strongly suppress the nonradiative decay and significantly facilitate the fluorescence pathway and intersystem crossing. Thus, it tremendously promotes phototheranostic efficacies in terms of NIR image‐guided cancer surgery and photodynamic therapy using a peritoneal carcinomatosis‐bearing mouse model. Collectively, it not only provides a novel strategy to advanced AIE dots for cancer phototheranostics, but also brings new insights into the design of superior fluorescent NPs for biomedical applications.