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AIM: To prepare a novel functionalized upconversion nanomaterial UCNPs-PEG-Tf through an improved method and observe its specific imaging phenomenon to choroidal melanoma cells(OCM-1).METHODS: NaYF4:Yb/Er(Up-conversion nanoparticles, UCNPs)was Prepared and plasma was treated to carboxylate the surface; then amino polyethylene glycol and transferrin(Tf)were respectively loaded to prepare UCNPs-PEG-Tf. Characterized them accordingly, its biocompatibility was tested accordingly, and the specific fluorescence phenomenon of OCM-1 was detected by fluorescence spectrophotometer and inverted fluorescence microscopy.RESULTS: Characterization confirmed successful synthesis of UCNPs, UCNPs-PEG, and further loading of Tf to form UCNPs-PEG-Tf. UCNPs-PEG-Tf showed excellent biocompatibility and emitted significant green fluorescence. Under the same conditions, fluorescence intensity measurement and observations from the inverted fluorescence microscope both demonstrated its significant specificity in imaging to OCM-1 cells.CONCLUSION: The synthesized novel functionalized UCNPs-PEG-Tf nanocomposite showed good biocompatibility and achieve specific imaging to OCM-1 cells.

Biothiols such as cysteine, homocysteine, and glutathione play significant roles in important biological activities, and their abnormal concentrations have been found to be closely associated with certain diseases, making their detection a critical task. To this end, fluorescent probes have become increasingly popular due to their numerous advantages, including easy handling, desirable spatiotemporal resolution, high sensitivity, fast response, and favorable biocompatibility. As a result, intensive research has been conducted to create fluorescent probes for the detection and imaging of biothiols. This brief review summarizes recent advances in the field of biothiol-responsive fluorescent probes, with an emphasis on rational probe design, including the reaction mechanism, discriminating detection, reversible detection, and specific detection. Furthermore, the challenges and prospects of fluorescence probes for biothiols are also outlined. [ABSTRACT FROM AUTHOR]

Purpose: Lipid droplets (LDs) are dynamic organelles which associated with many metabolic processes. Reliable long-term imaging of LD is of great importance in LD-based therapy and research. Conventional fluorescent probes suffer from poor photostability and difficulty of preparation, which compromise their LD imaging ability. In this study, we aim to provide a novel and universal fluorescent probe for LD-specific imaging in both eukaryotic and prokaryotic cells. The versatile and potential applications of the probe were also evaluated. Methods: We used one-step Suzuki coupling reaction to synthesize a fluoro-pyrazine-bridged donor–acceptor-donor fluorescent probe (T-FP-T). The fluorescent properties and stability of T-FP-T were detected. Then, LD-specific imaging and dynamic movement tracking capabilities of T-FP-T were studied in fungus, bacteria, plant and animal tissues. The biosafety and photodynamic toxicity of the probe under different light irradiation were characterized. Results: T-FP-T showed large Stokes shift, superior brightness, excellent photostability, low toxicity. T-FP-T exhibited significant overlaps with adipophilin antibody or the commercial LD probe (LipidSpot™) in the cytoplasm, but not with Mitotracker red, Lysotracker red and Peroxisome Labeling dye. Moreover, T-FP-T also showed efficient superoxide anion generation capability under white LED light irradiation. The viability of Hela cells co-treated with T-FP-T and 1-h white LED light irradiation decreased to 62%. Conclusions: All these outstanding capabilities make T-FP-T a new efficient LD-specific imaging probe. The generated superoxide anion from T-FP-T under white LED light irradiation could cause obvious cell death, which will inspire broad study in LD-targeted photodynamic therapy. [ABSTRACT FROM AUTHOR]

[Display omitted] • An enzymatically activated biosensor was designed named E-MB-tFNA. • E-MB-tFNA was self-powered and self-recycled. • E-MB-tFNA showed excellent stability. • E-MB-tFNA can specific imaging APE1 in situ. • E-MB-tFNA can used for monitoring drug resistance and achieving guided surgical excision in vivo. Specific imaging of tumor cells with high sensitivity is urgently needed for evaluating the risk of tumor metastasis and progression. However, traditional tumor cell imaging strategies are still restricted by limited tumor specificity and sensitivity due to off-tumor signal leakage and a lower content of the targets. Therefore, a self-powered and self-recycled strategy based on molecular beacon (MB) hybridized on tetrahedral framework DNA (E-MB-tFNA) using the endogenous enzyme, apurinic/apyrimidinic endonuclease 1 (APE1), was rationally developed for tumor cell-specific molecular imaging with superior spatial specificity and improved sensitivity. The apurinic/apyrimidinic site (AP site) can be specifically recognized and cleaved by APE1, and was modified on the stem and loop region of E-MB-tFNA. The resultant E-MB-tFNA can be specifically recognized and cleaved by APE1 in the cytoplasm, which is overexpressed in tumor cells compared to normal cells. In particular, once APE1 cleaves the AP site on the stem region (double-stranded DNA) of E-MB-tFNA, the self-powered and self-recycled sequences modified on the stem region of E-MB-tFNA is freed to hybridize with the loop region of E-MB-tFNA, prompting APE1 to further hydrolyze the E-MB-tFNA loop region and generate fluorescence signals. In addition, the self-powered and self-recycled sequences can be hybridized with other E-MB-tFNA to continuously and cyclically amplify the fluorescence signal. The experimental results of this study showed that the E-MB-tFNA has the capability to monitor drug resistance and achieve guided precision surgical excision in vivo with superior spatial specificity and improved sensitivity. In particular, E-MB-tFNA can realize the risk classification of neuroblastoma patients in clinical plasma. [ABSTRACT FROM AUTHOR]

We describe the use of quantitative retardance imaging, previously introduced in Aknoun et al. (2015), as a label-free method for in situ tissue imaging and extra-cellular matrix fiber organization study. A technical improvement of this quantitative retardance imaging technique, based on the use of a high-resolution quadri-wave lateral shearing interferometer, is implemented to perform fast quantitative linear retardance and retardance measurements on biological tissues. The technique combines a stack of quantitative phase images with varying polarization excitation to create retardance and orientation images at 1 Hz. This technique gives information about local retardance and structure of anisotropic components. In addition to bringing morphological information on unstained biopsies, it can reveal tumors development grades thanks to specific fiber organization imaging. In this present study, we demonstrate how this information can be used as tumor associated signature. We show the capability of our approach on mouse skin and human breast tissues. [ABSTRACT FROM AUTHOR]

[Display omitted] A positively charged H 2 S probe was designed, which exhibited a significantly enhanced responsiveness to H 2 S in the aggregated state due to the increased positive charge density on the aggregate surface. Under physiological conditions, the probe could be activated by H 2 S with specificity and sensitivity to release near-infrared fluorescence signal. • This probe showed aggregation enhanced responsiveness (AER) to H 2 S in physiological conditions. • This probe could be activated by H 2 S with specificity and sensitivity to release near-infrared fluorescence signal. • This probe could addresse the limitations of conventional organic molecular probes that aggregate in physiological environments leading to attenuated responses. • Endogenous H 2 S levels in living cells were successfully monitored by using this probe. The poor water solubility of traditional activatable organic molecular probes usually limits their detection ability in physiological environment. In this work, a positively charged H 2 S probe was designed, which exhibited a significantly enhanced responsiveness to H 2 S in the aggregated state due to the increased positive charge density on the aggregate surface. Under physiological conditions, the probe could be activated by H 2 S with specificity and sensitivity to release near-infrared fluorescence signal. Moreover, endogenous H 2 S levels in living cells were successfully monitored by using this probe. We expect that this probe can provide a new strategy for the design of activatable probes to break the limitation of poor water solubility of conventional organic molecular probes. [ABSTRACT FROM AUTHOR]

Targeted imaging of cancer cells is crucial for early diagnosis. Mucin is a transmembrane protein that is overexpressed by cancer cells and is considered a cancer target. Specific recognition of mucin by aptamers has been receiving increasing attention in recent years. In this study, we use DNA MUC1 aptamer as a protective agent and target molecule in the synthesis of ultra-small fluorescent gold nanoclusters (MUC1-AuNCs) via a simple one-step method. MUC1-AuNCs exhibited red fluorescence emission with excellent stability over a wide pH range and under strong illumination. Confocal images showed that the synthesized MUC1-AuNCs efficiently targeted mucin overexpressing 4T1 cancer cells, but were not observed in 293T normal cells. Furthermore, the MUC1-AuNCs had a 5667 ns lifetime and 235 nm Stokes shifts and markedly eliminated background interference, suggesting they are a promising fluorescent probe for cell-targeted labeling and imaging. Image 1 • Luminescent gold nanoclusters were synthesized by thiolated MUC1 DNA aptamer as template. • The MUC1-AuNCs demonstrate good stability, low toxicity and specific cancer cell targeting properties. • The MUC1-AuNCs with long fluorescence lifetimes and large stokes shift can reduce background interference. [ABSTRACT FROM AUTHOR]