Orchestrated Strategies for Developing Fluorophores for NIR-II Imaging

Endogenous Melanin and Hydrogen-Based Specific Activated Theranostics Nanoagents: A Novel Multi-Treatment Paradigm for Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a systemic autoimmune disorder characterized by excessive proliferation of rheumatoid arthritis synovial fibroblasts (RASFs) and accumulation of inflammatory cytokines. Exploring the suppression of RASFs and modulation of the RA microenvironment is considered a comprehensive strategy for RA. In this work, specifically activated nanoagents (MAHI NGs) based on the hypoxic and weakly acidic RA microenvironment are developed to achieve a second near-infrared fluorescence (NIR-II FL)/photoacoustic (PA) dual-model imaging-guided multi-treatment. Due to optimal size, the MAHI NGs passively accumulate in the diseased joint region and undergo rapid responsive degradation, precisely releasing functionalized components: endogenous melanin-nanoparticles (MNPs), hydrogen gas (H2), and indocyanine green (ICG). The released MNPs play a crucial role in ablating RASFs within the RA microenvironment through photothermal therapy (PTT) guided by accurate PA imaging. However, the regional hyperthermia generated by PTT may exacerbate reactive oxygen species (ROS) production and inflammatory response following cell lysis. Remarkably, under the acidic microenvironment, the controlled release of H2 exhibits precise synergistic antioxidant and anti-inflammatory effects with MNPs. Moreover, the ICG, the second near-infrared dye currently approved for clinical use, possesses excellent NIR-II FL imaging properties that facilitate the diagnosis of deep tissue diseases and provide the right time-point for PTT.

Mito-Specific Nutri-Hijacker Synergizing Mitochondrial Metabolism and Glycolysis Intervention for Enhanced Antitumor Bioenergetic Therapy

Metabolic rewiring, a dynamic metabolic phenotype switch, confers that tumors exist and proliferate after fitness (or preadaptation) in harsh environmental conditions. Glycolysis deprivation was considered to be a tumor's metabolic Achilles heel. However, metabolic configuration can flexibly retune the mitochondrial metabolic ability when glycolysis is scared, potentially resulting in more aggressive clones. To address the challenge of mitochondrial reprogramming, an antiglycolytic nanoparticle (GRPP NP) containing a novel mitochondrial-targeted reactive oxygen species (ROS) generator (diIR780) was prepared to hijack glucose and regulate mitochondria, thus completely eliminating tumorigenic energy sources. In this process, GRPP NPs@diIR780 can catalyze endogenous glucose, leading to significantly suppressed glycolysis. Moreover, diIR780 can be released and selectively accumulated around mitochondria to generate toxic ROS. These combined effects, in turn, can hamper mitochondrial metabolism pathways, which are crucial for driving tumor progression. This synchronous intervention strategy enables utter devastation of metabolic rewiring, providing a promising regiment to eradicate tumor lesions without recurrence.

NIR-II Fluorescent Probes for Fluorescence-Imaging-Guided Tumor Surgery

Second near-infrared (NIR-II) fluorescence imaging is the most advanced imaging fidelity method with extraordinary penetration depth, signal-to-background ratio, biocompatibility, and targeting ability. It is currently booming in the medical realm to diagnose tumors and is being widely applied for fluorescence-imaging-guided tumor surgery. To efficiently execute this modern imaging modality, scientists have designed various probes capable of showing fluorescence in the NIR-II window. Here, we update the state-of-the-art NIR-II fluorescent probes in the most recent literature, including indocyanine green, NIR-II emissive cyanine dyes, BODIPY probes, aggregation-induced emission fluorophores, conjugated polymers, donor-acceptor-donor dyes, carbon nanotubes, and quantum dots for imaging-guided tumor surgery. Furthermore, we point out that the new materials with fluorescence in NIR-III and higher wavelength range to further optimize the imaging results in the medical realm are a new challenge for the scientific world. In general, we hope this review will serve as a handbook for researchers and students who have an interest in developing and applying fluorescent probes for NIR-II fluorescence-imaging-guided surgery and that it will expedite the clinical translation of the probes from bench to bedside.

Facile synthesis of anthranilic acid based dual functionalized novel hyper cross-linked polymer for promising CO2 capture and efficient Cr3+ adsorption

A novel hyper cross-linked polymer of 2-Aminobenzoic acid (HCP-AA) is synthesized for the adsorption of Cr3+ and CO2. The Brunauer-Emmett-Teller surface area of HCP-AA is 615 m2 g-1. HCP-AA of particle size 0.5 nm showed maximum adsorption of Cr3+ for lab prepared wastewater (93%) while it was 88% for real industrial wastewater. It is might be due to electrostatic interactions, cation-π interactions, lone pair interactions and cation exchange at pH 7; contact time of 8 min; adsorbent dose 0.8 g. The adsorption capacity was calculated 52.63 mg g-1 for chromium metal ions at optimum conditions. Freundlich isotherm studies R2 = 0.9273 value is the best fit and follows pseudo second order kinetic model (R2 = 0.979). The adsorption is found non-spontaneous and exothermic through thermodynamic calculations like Gibbs free energy (ΔG), enthalpy change (ΔH) and entropy change (ΔS) were 6.58 kJ mol-1, - 60.91 kJ mol-1 and - 45.79 kJ mol-1 K-1, respectively. The CO2 adsorption capacity of HCP-AA is 1.39 mmol/g with quantity of 31.1 cm3/g (6.1 wt%) at 273Kwhile at 298 K adsorption capacity is 1.12 mmol/g with quantity 25.2 cm3/g (5 wt%). Overall, study suggests that carboxyl (-COOH) and amino (-NH2) groups may be actively enhancing the adsorption capacity of HCP-AA for Cr3+ and CO2.

Exploring flavylium-based SWIR emitters: Design, synthesis and optical characterization of dyes derivatized with polar moieties

Imaging in the shortwave infrared (SWIR, 1000-1700 nm) region is gaining traction for biomedical applications, leading to an in-depth search for fluorophores emitting at these wavelengths. The development of SWIR emitters, to be used in vivo in biological media, is mostly hampered by the considerable lipophilicity of the structures, resulting from the highly conjugated scaffold required to shift the emission to this region, that limit their aqueous solubility. In this work, we have modulated a known SWIR emitter, named Flav7, by adding hydrophilic moieties to the flavylium scaffold and we developed a new series of Flav7-derivatives, which proved to be indeed more polar than the parent compound, but still not freely water-soluble. Optical characterization of these derivatives allowed us to select FlavMorpho, a new compound with improved emission properties compared to Flav7. Encapsulation of the two compounds in micelles resulted in water-soluble SWIR emitters, with FlavMorpho micelles being twice as emissive as Flav7 micelles. The SWIR emission extent of FlavMorpho micelles proved also superior to the tail-emission of Indocyanine Green (ICG), the FDA-approved reference cyanine, in the same region, by exciting the probes at their respective absorption maxima in phosphate buffered saline (PBS) solution. The availability of optical imaging devices equipped with lasers able to excite these dyes at their maximum of absorption in the SWIR region, could pave the way for implemented SWIR imaging results.

Brightness Strategies toward NIR-II Emissive Conjugated Materials: Molecular Design, Application, and Future Prospects

Recent advances have been made in second near-infrared (NIR-II) fluorescence bioimaging and many related applications because of its advantages of deep penetration, high resolution, minimal invasiveness, and good dynamic visualization. To achieve high-performance NIR-II fluorescence bioimaging, various materials and probes with bright NIR-II emission have been extensively explored in the past few years. Among these NIR-II emissive materials, conjugated polymers and conjugated small molecules have attracted wide interest due to their native biosafety and tunable optical performance. This review summarizes the brightness strategies available for NIR-II emissive conjugated materials and highlights the recent developments in NIR-II fluorescence bioimaging. A concise, detailed overview of the molecular design and regulatory approaches is provided in terms of their high brightness, long wavelengths, and superior imaging performance. Then, various typical cases in which bright conjugated materials are used as NIR-II probes are introduced by providing step-by-step examples. Finally, the current problems and challenges associated with accessing NIR-II emissive conjugated materials for bright NIR-II fluorescence bioimaging are briefly discussed, and the significance and future prospects of these materials are proposed to offer helpful guidance for the development of NIR-II emissive materials.

Comparison of the In Vitro and In Vivo Behavior of a Series of NIR-II-Emitting Aza-BODIPYs Containing Different Water-Solubilizing Groups and Their Trastuzumab Antibody Conjugates

The development of new fluorescent organic probes effective in the NIR-II region is currently a fast-growing field and represents a challenge in the domain of medical imaging. In this study, we have designed and synthesized an innovative series of aza-boron dipyrromethenes emitting in the NIR-II region. We have investigated the effect of different water-solubilizing groups not only on the photophysical properties of the compounds but also on their in vitro and in vivo performance after bioconjugation to the antibody trastuzumab. Remarkably, we discovered that the most lipophilic compound unexpectedly displayed the most favorable in vivo properties after bioconjugation. This underlines the profound influence that the fluorophore functionalization approach can have on the efficiency of the resulting imaging agent.

Benzobisthiadiazole-Based Small Molecular Near-Infrared-II Fluorophores: From Molecular Engineering to Nanophototheranostics

Organic fluorescent molecules with emission in the second near-infrared (NIR-II) biological window have aroused increasing investigation in cancer phototheranostics. Among these studies, Benzobisthiadiazole (BBT), with high electron affinity, is widely utilized as the electron acceptor in constructing donor-acceptor-donor (D-A-D) structured fluorophores with intensive near-infrared (NIR) absorption and NIR-II fluorescence. Until now, numerous BBT-based NIR-II dyes have been employed in tumor phototheranostics due to their exceptional structure tunability, biocompatibility, and photophysical properties. This review systematically overviews the research progress of BBT-based small molecular NIR-II dyes and focuses on molecule design and bioapplications. First, the molecular engineering strategies to fine-tune the photophysical properties in constructing the high-performance BBT-based NIR-II fluorophores are discussed in detail. Then, their biological applications in optical imaging and phototherapy are highlighted. Finally, the current challenges and future prospects of BBT-based NIR-II fluorescent dyes are also summarized. This review is believed to significantly promote the further progress of BBT-derived NIR-II fluorophores for cancer phototheranostics.

A deep-red fluorophore based on naphthothiadiazole as emitter with hybridized local and charge transfer and ambipolar transporting properties for electroluminescent devices

Herein, we report the synthesis and characterization of an efficient ambipolar charge-carrier-transporting deep-red fluorophore (TPECNz) based on a donor-acceptor-donor (D-A-D)-type molecule and its application as a non-doped emitter in an organic light-emitting diode (OLED). The fluorophore TPECNz contains naphtho[2,3-c][1,2,5]thiadiazole (Nz) as a strong acceptor unit symmetrically functionalized with N-(4-(1,2,2-triphenylvinyl)phenyl)carbazole as a donor and aggregation-induced emission (AIE) luminogen. The experimental (solvatochromic and emission in THF/water mixtures studies) and theoretical investigations prove that TPECNz retains cooperative hybridized local and charge transfer (HLCT) and weak AIE features. Thanks to its D-A-D-type structure with a proper twist angle between the D and A units, a strong electron deficiency of the Nz unit, and electron-donating and hole-transporting natures of carbazole, TPECNz exhibits a strong deep red emission (λem = 648 nm) with a high fluorescence quantum yield of 96%, outstanding thermal property (Tg = 236 °C), and ambipolar charge-carrier-transporting property with a decent balance of mobility of electrons (1.50 × 10-5 cm2 V-1 s-1) and holes (4.42 × 10-6 cm2 V-1 s-1). TPECNz is successfully employed as a non-doped emitter in an OLED which displays deep red electroluminescent emission peaked at 659 nm with CIE coordinates of (0.664, 0.335)), an EQEmax of 3.32% and exciton utilization efficiency (EUE) of 47%.