A Promising NIR‐II Fluorescent Sensor for Peptide‐Mediated Long‐Term Monitoring of Kidney Dysfunction

Enzymes in Synergy: Bacteria Specific Molecular Probe for Locoregional Imaging of Urinary Tract Infection in vivo

Uropathogenic Escherichia coli (UPECs) is a leading cause for urinary tract infections (UTI), accounting for 70-90 % of community or hospital-acquired bacterial infections owing to high recurrence, imprecision in diagnosis and management, and increasing prevalence of antibiotic resistance. Current methods for clinical UPECs detection still rely on labor-intensive urine cultures that impede rapid and accurate diagnosis for timely UTI therapeutic management. Herein, we developed a first-in-class near-infrared (NIR) UPECs fluorescent probe (NO-AH) capable of specifically targeting UPECs through its collaborative response to bacterial enzymes, enabling locoregional imaging of UTIs both in vitro and in vivo. Our NO-AH probe incorporates a dual protease activatable moiety, which first reacts with OmpT, an endopeptidase abundantly present on the outer membrane of UPECs, releasing an intermediate amino acid residue conjugated with a NIR hemicyanine fluorophore. Such liberated fragment would be subsequently recognized by aminopeptidase (APN) within the periplasm of UPECs, activating localized fluorescence for precise imaging of UTIs in complex living environments. The peculiar specificity and selectivity of NO-AH, facilitated by the collaborative action of bacterial enzymes, features a timely and accurate identification of UPECs-infected UTIs, which could overcome misdiagnosis in conventional urine tests, thus opening new avenues towards reliable UTI diagnosis and personalized antimicrobial therapy management.

"Rigid-Flexible" Dual-Ferrocene Chimeric Nanonetwork for Simultaneous Tumor-Targeted Tracing and Photothermal/Photodynamic Therapy

There is an urgent need to develop phototherapeutic agents with imaging capabilities to assess the treatment process and efficacy in real-time during cancer phototherapy for precision cancer therapy. The safe near-infrared (NIR) fluorescent dyes have garnered significant attention and are desirable for theranostics agents. However, until now, achieving excellent photostability and fluorescence (FL) imaging capability in aggregation-caused quenching (ACQ) dyes remains a big challenge. Here, for the only FDA-approved NIR dye, indocyanine green (ICG), we developed a dual-ferrocene (Fc) chimeric nanonetwork ICG@HFFC based on the rigid-flexible strategy through one-step self-assembly, which uses rigid Fc-modified hyaluronic acid (HA) copolymer (HA-Fc) and flexible octadecylamine (ODA) bonded Fc (Fc-C18) as the delivery system. HA-Fc reserved the ability of HA to target the CD44 receptor of the tumor cell surface, and the dual-Fc region provided a rigid space for securely binding ICG through metal-ligand interaction and π-π conjugation, ensuring excellent photostability. Additionally, the alkyl chain provided flexible confinement for the remaining ICG through hydrophobic forces, preserving its FL. Thereby, a balance is achieved between outstanding photostability and FL imaging capability. In vitro studies showed improved photobleaching resistance, enhanced FL stability, and increased singlet oxygen (1O2) production efficiency in ICG@HFFC. Further in vivo results display that ICG@HFFC had good tumor tracing ability and significant tumor inhibition which also exhibited good biocompatibility.. Therefore, ICG@HFFC provides an encouraging strategy to realize simultaneous enhanced tumor tracing and photothermal/photodynamic therapy (PTT/PDT) and offers a novel approach to address the limitations of ACQ dyes.

Physiological principles underlying the kidney targeting of renal nanomedicines

Kidney disease affects more than 10% of the global population and is associated with considerable morbidity and mortality, highlighting a need for new therapeutic options. Engineered nanoparticles for the treatment of kidney diseases (renal nanomedicines) represent one such option, enabling the delivery of targeted therapeutics to specific regions of the kidney. Although they are underdeveloped compared with nanomedicines for diseases such as cancer, findings from preclinical studies suggest that renal nanomedicines may hold promise. However, the physiological principles that govern the in vivo transport and interactions of renal nanomedicines differ from those of cancer nanomedicines, and thus a comprehensive understanding of these principles is needed to design nanomedicines that effectively and specifically target the kidney while ensuring biosafety in their future clinical translation. Herein, we summarize the current understanding of factors that influence the glomerular filtration, tubular uptake, tubular secretion and extrusion of nanoparticles, including size and charge dependency, and the role of specific transporters and processes such as endocytosis. We also describe how the transport and uptake of nanoparticles is altered by kidney disease and discuss strategic approaches by which nanoparticles may be harnessed for the detection and treatment of a variety of kidney diseases.

In situ detection of alkaline phosphatase in a cisplatin-induced acute kidney injury model with a fluorescent/photoacoustic bimodal molecular probe

Kidneys play an important part in drug metabolism and excretion. High local concentration of drugs or drug allergies often cause acute kidney injury (AKI). Identification of effective biomarkers of initial stage AKI and constructing activable molecular probes with excellent detection properties for early evaluation of AKI are necessary, yet remain significant challenges. Alkaline phosphatase (ALP), a key hydrolyzing protease, exists in the epithelial cells of the kidney and is discharged into the urine following kidney injury. However, no studies have revealed its level in drug-induced AKI. Existing ALP fluorescent molecular probes are not suitable for testing and imaging of ALP in the AKI model. Drug-induced AKI is accompanied by oxidative stress, and many studies have indicated that a large increase in reactive oxygen species (ROS) occur in the AKI model. Thus, the probe used for imaging of AKI must be chemically stable in the presence of ROS. However, most existing near-infrared fluorescent (NIRF) ALP probes are not stable in the presence of ROS in the AKI model. Hence, we built a chemically stable molecular sensor (CS-ALP) to map ALP level in cisplatin-induced AKI. This novel probe is not destroyed by ROS generated in the AKI model, thus allowing high-fidelity imaging. In the presence of ALP, the CS-ALP probe generates a new absorbance peak at 685 nm and a fluorescent emission peak at 716 nm that could be used to "turn on" photoacoustic (PA) and NIRF imaging of ALP in AKI. Levels of CS-ALP build up rapidly in the kidney, and CS-ALP has been successfully applied in NIRF/PA bimodal in vivo imaging. Through the NIRF/PA bimodal imaging results, we demonstrate that upregulated expression of ALP occurs in the early stages of AKI and continues with injury progression.

An NO-responsive probe for detecting acute inflammation using NIR-II fluorescence/optoacoustic imaging

An activatable probe for detecting acute inflammation has been developed. Nitrosation turns electron-donating methylamine into electron-withdrawing methyl-N-nitroso with turn-on NIR-II fluorescence and optoacoustic signals for imaging.

Donor/π-Bridge Manipulation for Constructing a Stable NIR-II Aggregation-Induced Emission Luminogen with Balanced Phototheranostic Performance*

Owing to their versatile functionality and tunable energy dissipation, aggregation-induced emission luminogens (AIEgens) have emerged as a potential platform for multimodal theranostics. Nevertheless, the construction of AIE-active phototheranostic agents in the second near-infrared window (NIR-II, 1000-1700 nm), which allows superior resolution and minimized photodamage, is still a formidable challenge. Herein, benzo[c]thiophene serves as an electron-rich and bulky donor (D)/π-bridge, which can enlarge the conjugation length and distort the backbone of an AIEgen. By precise D/π-bridge engineering, highly stable NIR-II AIEgen DPBTA-DPTQ nanoparticles are obtained with acceptable NIR-II fluorescence quantum yield and excellent photothermal conversion efficiency. In addition, the spatial conformation of DPBTA-DPTQ is determined for the first time by X-ray single crystal diffraction and theoretical simulations. DPBTA-DPTQ NPs have good biocompatibility and show efficient photothermal therapeutic effects in in vitro tests. Furthermore, DPBTA-DPTQ NPs were used in fluorescence-photoacoustic-photothermal trimodal imaging-guided photothermal eradication of tumors in HepG2 and B16-F10 tumor-xenografted mice.