Bright, photostable and long-circulating NIR-II nanoparticles for whole-process monitoring and evaluation of renal transplantation

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

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

Room-temperature phosphorescent materials with Clusteroluminescence mechanism and applications from renewable resource of Xanthan gum derivatives

To face the energy crisis and global warming caused by the massive consumption of fossil resources, researchers worldwide are exploring new renewable resources to achieve sustainable development in future society. Based on this, renewable biomass from nature resource is expected to play a crucial role in low-carbon development. In this work, new renewable biomass of aggregation-induced emission (AIE) compound of cysteine based on Xanthan gum (Xag-Cys) derivatives with Clusteroluminescence mechanism and room-temperature phosphorescent (RTP) property was studied. Furthermore, it has the potential applications values in information encryption storage, moreover, it can also be as biosensor to detecting the concentration of H2S, GSH which used to diagnosing and monitoring of tumor cell in bioimaging.

From Molecule to Aggregate: Designing AIE Nanocrystals for Low-Power Backward Third-Harmonic Generation Angiography

Organic materials featuring third harmonic generation (THG) hold great promise for deep-tissue bioimaging due to their good biocompatibility and second near-infrared excitation. However, minimizing photodamage from the incident light necessitates significant improvements in the third-order nonlinear susceptibility. Herein, an organic luminogen called OTBP is developed as a backward THG (BTHG) contrast agent for second near-infrared (NIR-II) angiography. OTBP's intense absorption at 433 nm resonantly enhances its BTHG efficiency when excited by a 1300 nm femtosecond laser. In the aggregate state, the robust intermolecular interactions among OTBP molecules realize excellent crystallinity and the facile preparation of nanocrystals (NCs) with a high refractive index of 1.78. By leveraging Mie scattering theory, the best size of OTBP NCs for BTHG collection is attained. These integrated properties result in a high BTHG efficiency of OTBP NCs. Encapsulating the NCs with F-127 enables ultralow-power but high-contrast 3D vasculature imaging with negligible photodamage and background interference. Further elevating the laser power to 60 mW enables the visualization of microvessels at 500 µm with a high SNR of 143. This study offers insights into material design strategies toward efficient organic BTHG contrast agents and paves the way for the materials-oriented non-linear optics.

A Spiro-Based NIR-II Photosensitizer with Efficient ROS Generation and Thermal Conversion Performances for Imaging-Guided Tumor Theranostics

Organic photosensitizers (PSs) possessing NIR-II emission and photodynamic/photothermal effect have received a great sense of attention for their cutting-edge applications in imaging-guided multimodal phototherapy. However, it is highly challenging to design efficient PSs with high luminescence and phototherapy performance simultaneously. In this study, a spiro-functionalization strategy is proposed to alleviate aggregate-caused quenching of PSs and promote photodynamic therapy, and the strategy is verified via a spiro[fluorine-9,9'-xanthene]-modified NIR-II PS (named SFX-IC) with an acceptor-donor-acceptor configuration. SFX-IC-based nanoparticles (NPs) display a high molar extinction coefficient of 7.05 × 104 m‒1 cm-1 at 645 nm due to strong intramolecular charge-transfer characteristics. As expected, the as-prepared NPs show strong NIR-II emission with a fluorescence quantum yield of 1.1%, thanks to the spiro-configuration that suppressing excessively intermolecular π-π stacking. Furthermore, SFX-IC NPs not only efficiently generate 1O2 and O∙- 2 under 660 nm laser irradiation, but also possess good photothermal effect with photothermal conversion efficiency of 47.14%. Consequently, SFX-IC NPs can be served as versatile phototheranostic agents for NIR-II fluorescence/photoacoustic imaging-guided phototherapy, manifesting that the spiro-functionalized strategy is a powerful tool to construct efficient NIR-II emitting PSs.

Nucleophilic cleavage of C-F bonds by Brønsted base for rapid synthesis of fluorophosphate materials

Fluorochemicals are a rapidly expanding class of materials used in a variety of fields including pharmaceuticals, metallurgy, agrochemicals, refrigerants, and in particular, alkali metal ion batteries. However, achieving one-step synthesis of pure fluorophosphate compounds in a well-controlled manner remains a formidable challenge due to the volatilization of fluorine during the heat treatment process. One feasible method is to cleave the C-F bond in polytetrafluoroethylene (PTFE) during synthesis to create a fluorine-rich atmosphere and strongly reducing environment. However, the inert nature of the C-F bond in PTFE presents a significant obstacle, as it is the strongest single bond in organic compounds. To address this predicament, we propose a fluorine-compensating strategy that involves cleavage of the C-F bonds by nucleophilic SN2-type reactions of Brønsted base (ammonia) enabling fluorine compensation. The decomposed products (NH2· and C·) also result in the formation of micropores (via NH3 escape) and in-situ carbon coating (via C· polymerization). The resultant cathode delivers a superior potassium storage capability including high rate performance and capacity retention. This contribution not only overcomes the obstacles associated with the inert C-F bond in fluororesin, but also represents a significant step forward in the development of fluorine-containing compounds.

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.

Aggregation-Induced Emission Luminogens Realizing High-Contrast Bioimaging

A revolutionary transformation in biomedical imaging is unfolding with the advent of aggregation-induced emission luminogens (AIEgens). These cutting-edge molecules not only overcome the limitations of traditional fluorescent probes but also improve the boundaries of high-contrast imaging. Unlike conventional fluorophores suffering from aggregation-caused quenching, AIEgens exhibit enhanced luminescence when aggregated, enabling superior imaging performance. This review delves into the molecular mechanisms of aggregation-induced emission (AIE), demonstrating how strategic molecular design unlocks exceptional luminescence and superior imaging contrast, which is crucial for distinguishing healthy and diseased tissues. This review also highlights key applications of AIEgens, such as time-resolved imaging, second near-infrared window (NIR-II), and the advancement of AIEgens in sensitivity to physical and biochemical cue-responsive imaging. The development of AIE technology promises to transform healthcare from early disease detection to targeted therapies, potentially reshaping personalized medicine. This paradigm shift in biophotonics offers efficient tools to decode the complexities of biological systems at the molecular level, bringing us closer to a future where the invisible becomes visible and the incurable becomes treatable.

Engineered Nanoparticles for Theranostic Applications in Kidney Repair

Kidney diseases are characterized by their intricate nature and complexity, posing significant challenges in their treatment and diagnosis. Nanoparticles (NPs), which can be further classified as synthetic and biomimetic NPs, have emerged as promising candidates for treating various diseases. In recent years, the development of engineered nanotherapeutics has focused on targeting damaged tissues and serving as drug delivery vehicles. Additionally, these NPs have shown superior sensitivity and specificity in diagnosis and imaging, thus providing valuable insights for the early detection of diseases. This review aims to focus on the application of engineered synthetic and biomimetic NPs in kidney diseases in the aspects of treatment, diagnosis, and imaging. Notably, the current perspectives and challenges are evaluated, which provide inspiration for future research directions, and encourage the clinical application of NPs in this field.

Shedding light on vascular imaging: the revolutionary role of nanotechnology

Vascular dysfunction, characterized by changes in anatomy, hemodynamics, and molecular expressions of vasculatures, is closely linked to the onset and development of diseases, emphasizing the importance of its detection. In clinical practice, medical imaging has been utilized as a significant tool in the assessment of vascular dysfunction, however, traditional imaging techniques still lack sufficient resolution for visualizing the complex microvascular systems. Over the past decade, with the rapid advancement of nanotechnology and the emergence of corresponding detection facilities, engineered nanomaterials offer new alternatives to traditional contrast agents. Compared with conventional small molecule counterparts, nanomaterials possess numerous advantages for vascular imaging, holding the potential to significantly advance related technologies. In this review, the latest developments in nanotechnology-assisted vascular imaging research across different imaging modalities, including contrast-enhanced magnetic resonance (MR) angiography, susceptibility-weighted imaging (SWI), and fluorescence imaging in the second near-infrared window (NIR-II) are summarized. Additionally, the advancements of preclinical and clinical studies related to these nanotechnology-enhanced vascular imaging approaches are outlined, with subsequent discussion on the current challenges and future prospects in both basic research and clinical translation.

Aggregation-Induced Emission Luminogen: Role in Biopsy for Precision Medicine

Biopsy, including tissue and liquid biopsy, offers comprehensive and real-time physiological and pathological information for disease detection, diagnosis, and monitoring. Fluorescent probes are frequently selected to obtain adequate information on pathological processes in a rapid and minimally invasive manner based on their advantages for biopsy. However, conventional fluorescent probes have been found to show aggregation-caused quenching (ACQ) properties, impeding greater progresses in this area. Since the discovery of aggregation-induced emission luminogen (AIEgen) have promoted rapid advancements in molecular bionanomaterials owing to their unique properties, including high quantum yield (QY) and signal-to-noise ratio (SNR), etc. This review seeks to present the latest advances in AIEgen-based biofluorescent probes for biopsy in real or artificial samples, and also the key properties of these AIE probes. This review is divided into: (i) tissue biopsy based on smart AIEgens, (ii) blood sample biopsy based on smart AIEgens, (iii) urine sample biopsy based on smart AIEgens, (iv) saliva sample biopsy based on smart AIEgens, (v) biopsy of other liquid samples based on smart AIEgens, and (vi) perspectives and conclusion. This review could provide additional guidance to motivate interest and bolster more innovative ideas for further exploring the applications of various smart AIEgens in precision medicine.

Study of transient absorption spectroscopy of a D-π-A structure aggregation-induced emission luminogen and its photodynamic therapy application

Photodynamic therapy (PDT) represents an emerging and noninvasive modality that has gained clinical approval for the treatment of cancers, leveraging photosensitizers for optimal therapeutic efficacy. In this study, we synthesized a photosensitizer (denoted as DTCSPP) exhibiting a donor-π-acceptor (D-π-A) structural motif. The DTCSPP manifests aggregation-induced emission (AIE) characteristics, along with good biocompatibility and mitochondrial targeting capabilities attributed to its intrinsic charge and D-π-A architecture. The excited-state intramolecular charge transfer of DTCSPP was systematically investigated in both solution and aggregate states using femtosecond transient absorption spectroscopy (fs-TA). The fs-TA results revealed that DTCSPP exhibited a more rapid and facile excited-state molecular motion in the solution state compared to the aggregate state, implying the predominance of nonradiative decay in its photophysical processes within the solution. Given its ability to simultaneously generate type I and type II reactive oxygen species and induce ferroptosis and autophagy in cancer cells, DTCSPP demonstrates effectiveness in PDT at both cellular and in vivo levels. This study contributes a comprehensive understanding of the excited-state intramolecular charge transfer dynamics of charged D-π-A type AIE photosensitizers, shedding light on their potential application in PDT. The multifaceted capabilities of DTCSPP underscore its promise in advancing the field of anticancer therapeutics, providing valuable insights for the identification of anticancer targets and the development of novel drugs.

Aggregation-induced emission photosensitizer for antibacterial therapy of methicillin-resistant Staphylococcus aureus

A cationic aggregation-induced emission photosensitizer (AIE-PS) MNNPyBB has been reported to have antibacterial effects against both Gram-positive and Gram-negative bacteria. The bacterial kill mechanism has been investigated and elucidated. In a methicillin-resistant Staphylococcus aureus subcutaneous infection model, wound closure has been achieved with normal re-epithelialization and preserved skin morphology.