A dual-responsive ratiometric indicator designed for in vivo monitoring of oxidative stress and antioxidant capacity

Development of a dual-responsive ratiometric fluorescent probe for real-time sequential detection of H2O2 and Ag. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2025;333:125855. [PMID: 39946858 DOI: 10.1016/j.saa.2025.125855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Hydrogen peroxide (H2O2) and silver ions (Ag+) are of considerable interest due to their critical roles in chemical and biological processes and their potential environmental and health risks. In this study, a novel dual-response ratiometric fluorescent probe (FBHP), based on an internal charge transfer (ICT) mechanism, was designed and synthesized for the real-time dual detection of H2O2 and Ag+. The probe utilizes triphenylamine as a luminescent platform, while azacrown [N, S, O] groups and phenylboronic pinacol ester groups serve as recognition sites for Ag+ and H2O2, respectively. Experimental results demonstrate that FBHP exhibits high sensitivity and excellent selectivity for H2O2 and Ag+, achieving detection limits of 0.261 μM for H2O2 and 0.021 μM for Ag+. During sequential real-time detection of H2O2 and Ag+, the probe undergoes distinct three-channel fluorescence color changes, with fluorescence colors transitioning sequentially from red to blue and then to yellow. It also features a large Stokes shift of 194 nm and functions efficiently across a broad pH range (4 to 9). In conclusion, the real-time sequential dual-responsive ratiometric fluorescent probe FBHP offers significant advantages for the detection of H2O2 and Ag+, making it highly suitable for applications in environmental monitoring and biomedical research. This probe represents an efficient and reliable tool for analyzing and detecting H2O2 and Ag+ in various fields. Future work may focus on further structural modifications to enhance its detection performance and broaden its application scope.

Rational Design of NIR-II Ratiometric Fluorescence Probes for Accurate Bioimaging and Biosensing In Vivo

Intravital fluorescence imaging in the second near-infrared window (NIR-II, 900-1700 nm) has emerged as a promising method for non-invasive diagnostics in complex biological systems due to its advantages of less background interference, high tissue penetration depth, high imaging contrast, and sensitivity. However, traditional NIR-II fluorescence imaging, which is characterized by the "always on" or "turn on" mode, lacks the ability of quantitative detection, leading to low reproducibility and reliability during bio-detection. In contrast, NIR-II ratiometric fluorescence imaging can realize quantitative and reliable analysis and detection in vivo by providing reference signals for fluorescence correction, generating new opportunities and prospects during in vivo bioimaging and biosensing. In this review, the current design strategies and sensing mechanisms of NIR-II ratiometric fluorescence probes for bioimaging and biosensing applications are systematically summarized. Further, current challenges, future perspectives and opportunities for designing NIR-II ratiometric fluorescence probes are also discussed. It is hoped that this review can provide effective guidance for the design of NIR-II ratiometric fluorescence probes and promote its adoption in reliable biological imaging and sensing in vivo.

Dual oxidative stress biomarkers co-recognition in periodontal microenvironment: A flexible and low-power consumption nanozyme sensing platform

Sensing platforms with high interference immunity and low power consumption are crucial for the co-detection of dual oxidative stress biomarkers and clinical diagnosis of periodontitis. Herein, we constructed a bifunctional nanozyme to identify hydrogen peroxide (H2O2) and ascorbic acid (AA) with low crosstalk at zero or low bias voltage. To target H2O2 and AA, Fe(III) meso-tetra(4-carboxyphenyl) porphine (TCPP(Fe)) and Pt nanoclusters were selected as active sites respectively, and titanium carbide nanosheets were additionally introduced as a sensitizer. Due to their highly efficient catalytic properties, self-powered detection of H2O2 without bias voltage and distinguishable AA detection at 0.45 V were successfully achieved. Density functional theory calculations further confirmed the binding sites for target molecules and elucidated the sensing mechanism. On this basis, a dual-channel screen-printed electrode was fabricated to further ensure the discriminative detection of dual biomarkers at the device level. The constructed flexible, low-power consumption sensing platform was successfully applied to raw clinical samples, effectively distinguishing between healthy individuals and patients with varying degrees of periodontitis. This work is expected to provide new insights into the design of highly specific nanozymes and low-power consumption electrochemical sensing systems, which will contribute to the accurate and convenient diagnosis of periodontitis.

Non-invasive diagnosis of bacterial and non-bacterial inflammations using a dual-enzyme-responsive fluorescent indicator

Bacterial infections, as the second leading cause of global death, are commonly treated with antibiotics. However, the improper use of antibiotics contributes to the development of bacterial resistance. Therefore, the accurate differentiation between bacterial and non-bacterial inflammations is of utmost importance in the judicious administration of clinical antibiotics and the prevention of bacterial resistance. However, as of now, no fluorescent probes have yet been designed for the relevant assessments. To this end, the present study reports the development of a novel fluorescence probe (CyQ) that exhibits dual-enzyme responsiveness. The designed probe demonstrated excellent sensitivity in detecting NTR and NAD(P)H, which served as critical indicators for bacterial and non-bacterial inflammations. The utilization of CyQ enabled the efficient detection of NTR and NAD(P)H in distinct channels, exhibiting impressive detection limits of 0.26 μg mL-1 for NTR and 5.54 μM for NAD(P)H, respectively. Experimental trials conducted on living cells demonstrated CyQ's ability to differentiate the variations in NTR and NAD(P)H levels between A. baumannii, S. aureus, E. faecium, and P. aeruginosa-infected as well as LPS-stimulated HUVEC cells. Furthermore, in vivo zebrafish experiments demonstrated the efficacy of CyQ in accurately discerning variations in NTR and NAD(P)H levels resulting from bacterial infection or LPS stimulation, thereby facilitating non-invasive detection of both bacterial and non-bacterial inflammations. The outstanding discriminatory ability of CyQ between bacterial and non-bacterial inflammation positions it as a promising clinical diagnostic tool for acute inflammations.