Molecular Engineering of NIR-II/IIb Emitting AIEgen for Multimodal Imaging-Guided Photo-Immunotherapy

Deconvoluting capping ligand influence on photophysical properties in tetrathiafulvalene-based diradicaloids

Tetrathiafulvalene-2,3,6,7-tetrathiolate (TTFtt) complexes are synthetically tunable and emit brightly in the near-infrared II region (NIR II, 1000-1700 nm). Their emission/absorption energies respond to the identity of the capping ligands on the metal center, but a detailed understanding of how ligand bonding interactions dictate photophysical properties is key to predictive design optimization. Here we assess the relative influence of ligand pi (π) backbonding versus sigma (σ) donation in these complexes across a new series of olefin- and phosphite-capped complexes. Increasing the backbonding character of peripheral ligands results in a hypsochromic shift in the absorption maxima, while stronger σ donation results in a bathochromic shift.

Dual-Activatable Nano-Immunomodulator for NIR-II Fluorescence Imaging-Guided Precision Cancer Photodynamic Immunotherapy

Photodynamic immunotherapy which combines photodynamic therapy with immunotherapy has become an important and effective method for the treatment of cancer. However, most cancer photodynamic immunotherapeutic systems are not able to achieve precise release of immunomodulators, resulting in systemic side effects and poor patient outcomes. Herein, a dual-activatable nano-immunomodulator (DIR NP), which both its photodynamic effect and agonist release can be activated under specific stimuli, is reported for precision cancer photodynamic immunotherapy. The DIR NP is self-assembled from an R848-conjugated amphiphilic polymer (mPEG-TK-R848) and a hydrophobic oxidized bovine serum albumin (BSA-SOH)-conjugatable photosensitizer (DIR). DIR NPs may generate a small amount of 1O2 under 808 nm laser irradiation, leading to the cleavage of thioketal (TK) moiety and release of R848 and DIR. The released DIR may conjugate with tumor-overexpressed BSA-SOH, improving its photodynamic efficiency and NIR-II fluorescence signal. Such photodynamic efficiency improvement may further enhance the release of cargoes upon irradiation. The activated photodynamic effect induces immunogenic cell death (ICD) to release immune factors and R848 can enhance the maturation of dendritic cells for inhibiting the growth of both primary and distant tumors and eliminating lung metastasis. Therefore, this study provides a dual-activatable intelligent nano-immunomodulator for precise regulation of tumor photodynamic immunotherapy.

A high-performance organic fluorescent probe with aggregation-induced emission properties for long-term tumor monitoring

Near-infrared organic fluorescent probes have great need in biological sciences and medicine but most of them are still largely unable to meet demand. In this work, a delicate multipurpose organic fluorescent probe (DPPM-TPA) with aggregation-induced emission performances is designed and prepared by facile method to reflect fluorescence labeling, two-photon imaging, and long-term fluorescent tracking. Specifically, DPPM-TPA NPs was constructed from 4-(diphenylamino)phenylboronic acid and DPPM-Br by classical Suzuki coupling reaction and then coated with F127. Such nanoprobe possessed high stability in diverse medium under ambient temperatures, low cytotoxicity, and brilliant fluorescence performance. More importantly, DPPM-TPA NPs showed excellent two-photon imaging and extraordinary long-term fluorescence tracing capacity to malignant tumor, and it can last up to 9 days. These results indicated that DPPM-TPA NPs is expected to serve as a fluorescent probe for photodiagnostic and providing a new idea for the development of long-term fluorescent tracker.

Immunogenic cell stress and death in the treatment of cancer

The successful treatment of oncological malignancies which results in long-term disease control or the complete eradication of cancerous cells necessitates the onset of adaptive immune responses targeting tumor-specific antigens. Such desirable anticancer immunity can be triggered via the induction of immunogenic cell death (ICD) of cancer cells, thus converting malignant cells into an in situ vaccine that elicits T cell mediated adaptive immune responses and establishes durable immunological memory. The exploration of ICD for cancer treatment has been subject to extensive research. However, functional heterogeneity among ICD activating therapies in many cases requires specific co-medications to achieve full-blown efficacy. Here, we described the hallmarks of ICD and classify ICD activators into three distinct functional categories namely, according to their mode of action: (i) ICD inducers, which increase the immunogenicity of malignant cells, (ii) ICD sensitizers, which prime cellular circuitries for ICD induction by conventional cytotoxic agents, and (iii) ICD enhancers, which improve the perception of ICD signals by antigen presenting dendritic cells. Altogether, ICD induction, sensitization and enhancement offer the possibility to convert well-established conventional anticancer therapies into immunotherapeutic approaches that activate T cell-mediated anticancer immunity.

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.

J-Aggregation Strategy toward Potentiated NIR-II Fluorescence Bioimaging of Molecular Fluorophores

Molecular fluorophores emitting in the second near-infrared (NIR-II, 1000-1700 nm) window with strong optical harvesting and high quantum yields hold great potential for in vivo deep-tissue bioimaging and high-resolution biosensing. Recently, J-aggregates are harnessed to engineer long-wavelength NIR-II emitters and show unique superiority in tumor detection, vessel mapping, surgical navigation, and phototheranostics due to their bathochromic-shifted optical bands in the required slip-stacked arrangement aggregation state. However, despite the preliminary progress of NIR-II J-aggregates and theoretical study of structure-property relationships, further paradigms of NIR-II J-aggregates remain scarce due to the lack of study on aggregated fluorophores with slip-stacked fashion. In this effort, how to utilize the specific molecular structure to form slip-stacked packing motifs with J-type aggregated exciton coupling is emphatically elucidated. First, several molecular regulating strategies to achieve NIR-II J-aggregates containing intermolecular interactions and external conditions are positively summarized and deeply analyzed. Then, the recent reports on J-aggregates for NIR-II bioimaging and theranostics are systematically summarized to provide a clear reference and direction for promoting the development of NIR-II organic fluorophores. Eventually, the prospective efforts on ameliorating and promoting NIR-II J-aggregates to further clinical practices are outlined.

Controlled plasmon-induced nonlinear absorption and optical limiting in Al/PVP composite nanofibers

The effect of aluminum (Al) concentration on the surface plasmon resonance (SPR) band position of aluminum/polyvinylpyrrolidone (Al/PVP) composite nanofibers was investigated to strengthen nonlinear absorption (NLA) and widen its spectral range. With increasing Al content in PVP nanofibers, the SPR band was shifted towards excitation wavelength and an improved NLA response was achieved. The NLA response was examined both experimentally, by conducting Z-scan experiments, and theoretically, using two models. In the first model, the contributions of one-photon absorption (OPA), two-photon absorption (TPA), excited state absorption (ESA) and saturated absorption (SA) are considered. The second model, on the other hand, is a model that is widely used in the literature, and while taking into account the contributions of OPA and TPA, it neglects the ESA. The first model provides more accurate results due to the high concentration of free carriers in the samples examined. In order to reveal the contribution of Al to the nonlinear absorption, a laser excitation wavelength of 532 nm was chosen to minimize both the defect-assisted sequential and genuine two-photon absorption contributions of PVP. While the nonlinear absorption of pure PVP is quite weak, the NLA performance of Al/PVP nanofibers significantly improved as the Al content increased. As the amount of Al increased, the aggregation effect increased and a broadening and red shift in the SPR band were observed in the plasmonic behavior. This indicates a decreasing interparticle distance in Al particles. The sample with the highest amount of Al is anticipated as a potential candidate for optical limiting (OL) applications due to its superior NLA performance and SPR band furthest towards the near infrared (NIR) region, allowing a wider range of wavelength set to be used in OL applications.

Theranostic Lipid Nanoparticles for Renal Cell Carcinoma

Renal cell carcinoma (RCC) is a common urological malignancy and represents a leading threat to healthcare. Recent years have seen a series of progresses in the early diagnosis and management of RCC. Theranostic lipid nanoparticles (LNPs) are increasingly becoming one of the focuses in this field, because of their suitability for tumor targeting and multimodal therapy. LNPs can be precisely fabricated with desirable chemical compositions and biomedical properties, which closely match the physiological characteristics and clinical needs of RCC. Herein, a comprehensive review of theranostic LNPs is presented, emphasizing the generic tool nature of LNPs in developing advanced micro-nano biomaterials. It begins with a brief overview of the compositions and formation mechanism of LNPs, followed with an introduction to kidney-targeting approaches, such as passive, active, and stimulus responsive targeting. With examples provided, a series of modification strategies for enhancing the tumor targeting and functionality of LNPs are discussed. Thereafter, research advances on applications of these LNPs for RCC including bioimaging, liquid biopsy, drug delivery, physical therapy, and gene therapy are summarized and discussed from an interdisciplinary perspective. The final part highlights the milestone achievements of translation medicine, current challenges as well as future development directions of LNPs for the diagnosis and treatment of RCC.