Specific and Long-Term Luminescent Monitoring of Hydrogen Peroxide in Tumor Metastasis

Self-Regenerating Photothermal Agents for Tandem Photothermal and Thermodynamic Tumor Therapy

Small molecule-based photothermal agents (PTAs) hold promising future for photothermal therapy; however, unexpected inactivation exerts negative impacts on their application clinically. Herein, a self-regenerating PTA strategy is proposed by integrating 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS•+) with a thermodynamic agent (TDA) 2,2'-azobis[2-(2-imidazolin-2-yl) propane] dihydrochloride (AIPH). Under NIR laser, the photothermal effect of ABTS•+ accelerates the production of alkyl radicals by AIPH, which activates the regeneration of ABTS•+, thus creating a continuous positive feedback loop between photothermal and thermodynamic effects. The combination of ABTS•+ regeneration and alkyl radical production leads to the tandem photothermal and thermodynamic tumor therapy. In vitro and in vivo experiments confirm that the synergistic action of thermal ablation, radical damage, and oxidative stress effectively realizes tumor suppression. This work offers a promising approach to address the unwanted inactivation of PTAs and provides valuable insights for optimizing combination therapy.

A scalable fabrication method for gold nanodisk-upconverting nanoparticle hybrid nanostructures

Plasmonic nanostructures can be used to enhance the efficiency of upconversion nanoparticles (UCNPs) and enable new functionalities. However, the fabrication of these hybrid plasmon-UCNP nanostructures has traditionally relied on either wet chemistry or nanolithography routes that are difficult to control, scale up, or both. In this work, we present a scalable nanofabrication process, capable of producing a massive array of gold-UCNP hybrid nanostructures over a few mm2 area and with excellent uniformity in the photoluminescence intensity. This new approach combines the scalability of the bottom-up self-assembly method and the precision of the top-down nanolithography approach. It provides an efficient alternative route for the production of plasmonically enhanced UCNPs. A detailed discussion on the optimization of the UCNP self-assembly, the gold nanodisk lithography, and the nanopattern transfer processes is presented here. Additionally, we showcase the potential of this new approach for fabricating mechanical force sensors based on the selective plasmonic enhancement of the UCNP emission. This new approach holds great potential in facilitating the production of plasmonically enhanced UCNPs that can be deployed for both imaging and sensing applications.

Preparation of copper nanoparticles fluorescent probes and detection of hydrogen peroxide and glucose

Fluorescent copper nanoparticles (CuNPs) was synthesized by one-step chemical reduction method using ascorbic acid (AA) and copper sulfate (CuSO4⋅5H2O) as raw materials, which had good water solubility and fluorescence properties. A green, simple and safe CuNPs@Fe2+ fluorescence probe was developed for the detection of hydrogen peroxide and glucose using Fe2+ as a bridge. The prepared CuNPs could obtain the maximum fluorescence emission wavelength at 440 nm when the excitation wavelength was 360 nm. The average particle size of CuNPs was 10 nm, which had good photobleach resistance, stability and salt tolerance. The fluorescence intensity was quenched due to electron transfer (ET) process when hydrogen peroxide was added to CuNPs@Fe2+ system. This result was mainly because Fenton reaction occured between hydrogen peroxide and Fe2+, producing hydroxyl free radicals (OH) and Fe3+. Since glucose could be catalyzed by specific glucose oxidase (GOX) to produce H2O2 and corresponding oxidation products, the quantitative analysis of glucose was realized when glucose oxidase was introduced into the CuNPs@Fe2+ sensor system. Therefore, a novel CuNPs@Fe2+ fluorescent probe sensor study was constructed to further achieve quantitative detection of H2O2 and glucose. Under the optimized experimental conditions, the linear ranges for H2O2 and glucose were 28.219-171.562 μM and 1.237-75.771 μM, respectively. And the detection limits for H2O2 and glucose were 7.169 μM and 0.540 μM, respectively. In addition, the mechanism of fluorescence probe quenching caused by the interaction between H2O2 and CuNPs@Fe2+ was also discussed. The proposed sensing system had been applied successfully to the detection of glucose in human serum samples.

Boosting Dye-Sensitized Luminescence by Enhanced Short-Range Triplet Energy Transfer

Dye-sensitization can enhance lanthanide-based upconversion luminescence, but is hindered by interfacial energy transfer from organic dye to lanthanide ion Yb3+ . To overcome these limitations, modifying coordination sites on dye conjugated structures and minimizing the distance between fluorescence cores and Yb3+ in upconversion nanoparticles (UCNPs) are proposed. The specially designed near-infrared (NIR) dye, disulfo-indocyanine green (disulfo-ICG), acts as the antenna molecule and exhibits a 2413-fold increase in luminescence under 808 nm excitation compared to UCNPs alone using 980 nm irradiation. The significant improvement is attributed to the high energy transfer efficiency of 72.1% from disulfo-ICG to Yb3+ in UCNPs, with majority of energy originating from triplet state (T1 ) of disulfo-ICG. Shortening the distance between the dye and lanthanide ions increases the probability of energy transfer and strengthens the heavy atom effect, leading to enhanced T1 generation and improved dye-triplet sensitization upconversion. Importantly, this approach also applies to 730 nm excitation Cy7-SO3 sensitization system, overcoming the spectral mismatch between Cy7 and Yb3+ and achieving a 52-fold enhancement in luminescence. Furthermore, the enhancement of upconversion at single particle level through dye-sensitization is demonstrated. This strategy expands the range of NIR dyes for sensitization and opens new avenues for highly efficient dye-sensitized upconversion systems.