In situ synthesized nanozyme for photoacoustic-imaging-guided photothermal therapy and tumor hypoxia relief

Zinc phthalocyanine and sulfasalazine coloaded nanoaggregates with Prussian blue functionalization for sensitizing tumor photothermal/photodynamic therapy

Photothermal therapy/photodynamic therapy (PTT/PDT), as a noninvasive therapeutic modality, has been extensively applied in superficial tumor treatment. However, their curative effects were largely weakened due to hypoxia and an elevated glutathione (GSH) microenvironment. Herein, zinc phthalocyanine (ZnPc) and sulfasalazine (SAS) coloaded nanoaggregates (Z-S@B NAs) with Prussian blue (PB) functionalization (PB/Z-S@B NAs) were fabricated via self-assembly and using an in situ oxidative polymerization method for tumor PTT/PDT sensitization. The designed PB/Z-S@B NAs were capable of triggering local hyperthermia and generating substantial reactive oxygen species (ROS) under 660- and 808-nm laser irradiation. Notably, the PB/Z-S@B NAs exhibited favorable catalase-like (CAT-like) activity that decomposed hydrogen peroxide into oxygen, which further enhanced tumor cell sensitivity to PTT/PDT. Moreover, SAS from the PB/Z-S@B NAs remarkably decreased the antioxidant GSH level, resulting in a synergetic tumor-killing effect. Collectively, this study provides a versatile nanoplatform to overcome intrinsic antitumor effect and enhance tumor sensitivity to PTT/PDT.

Inhibition of the cGAS-STING pathway via an endogenous copper ion-responsive covalent organic framework nanozyme for Alzheimer's disease treatment

Inhibition of cGAS-STING overactivation has recently emerged as a promising strategy to counteract Alzheimer's disease (AD). However, current cGAS-STING inhibitors as immunosuppressants suffer from instability, non-specific targeting, and innate immune disruption. Here, an endogenous AD brain copper ion-responsive covalent organic framework (COF)-based nanozyme (denoted as TP@PB-COF@NADH) has been designed for targeted inhibition of the cGAS-STING pathway for AD treatment. The effective trapping of excess brain endogenous copper ions by TP@PB-COF@NADH not only inhibits the Cu2+-induced harmful reactive oxygen species (ROS) production which is one of the mediators of cGAS-STING activation, but also activates the nanozyme activity of TP@PB-COF@NADH. Furthermore, the well-prepared nanozyme catalytically generates NAD+ and consumes hydrogen peroxide (H2O2) through second near-infrared (NIR-II) enhanced nicotinamide adenine dinucleotide (NADH) peroxidase (NPX)-like activity, realizing the efficient inhibition of the cGAS-STING pathway and associated neuroinflammation. Moreover, replenishing NAD+ levels efficiently restores mitochondrial function and ATP supply. In vivo studies demonstrate that TP@PB-COF@NADH with NIR-II irradiation significantly improves cognitive function in 3× Tg-AD mice, with a reduction in amyloid-β (Aβ) plaque, neuroinflammation and neuronal damage. Collectively, this work presents a promising approach for AD treatment by using an AD brain harmful excess endogenous copper ion-responsive and efficient nanozyme.

Therapeutic and Contrast Agents for Photoacoustic Imaging-Guided Photothermal Therapy: A Narrative Review

Photoacoustic imaging is a hybrid modality that combines high-contrast and spectroscopy-based optical imaging specificity with the high spatial resolution of ultrasonography. This review highlights the development and progress of photoacoustic imaging technology over the past decade. This imaging technology has evolved to be more user-friendly, cost-effective, and portable, demonstrating its potential for diverse clinical applications. A potential clinical application lies in the use of photoacoustic imaging as a guiding tool for photothermal therapy. This review was conducted by initially filtering through three databases, namely, Google Scholar, PubMed, and Scopus, resulting in 460 articles published between 2019 and May 2023. Of these, 54 articles were deemed suitable for review after identification. The selected articles were research papers focusing on the development of therapeutic agents that enhance contrast in photoacoustic imaging. All reviewed articles tested these agents both in vitro and in vivo. This review focuses on wavelength absorption and radiation sources for photothermal therapy. The developed agents predominantly used NIR-I wavelengths, whereas the NIR-II region has been less explored, indicating significant potential for future research. This review provides comprehensive insights into the advancement of compounds serving as therapeutic agents and contrast agents in photoacoustic imaging-guided photothermal therapy.

A dual-mode fluorometric/colorimetric sensor for sulfadimethoxine detection based on Prussian blue nanoparticles and carbon dots

A dual-mode (colorimetric/fluorescence) nanoenzyme-linked immunosorbent assay (NLISA) was developed based on Au-Cu nanocubes generating Prussian blue nanoparticles (PBNPs). It is expected that this method can be used to detect the residues of sulfonamides in the field, and solve the problem of long analysis time and high cost of the traditional method. Sulfadimethoxine (SDM) was selected as the proof-of-concept target analyte. The Au-Cu nanocubes were linked to the aptamer by amide interaction, and the Au-Cu nanocubes, SDM and antibody were immobilized on a 96-well plate using the sandwich method. The assay generates PBNPs by oxidising the Cu shells on the Au-Cu nanocubes in the presence of hydrochloric acid, Fe3+ and K3[Fe (CN)6]. In this process, the copper shell undergoes oxidation to Cu2+ and subsequently Cu2 + further quenches the fluorescence of the carbon point. PBNPs exhibit peroxidase-like activity, oxidising 3,3',5,5'-tetramethylbenzidine (TMB) to OX-TMB in the presence of H2O2, which alters the colorimetric signal. The dual-mode signals are directly proportional to the sulfadimethoxine concentration within the range 10- 3~10- 7 mg/mL. The limit of detection (LOD) of the assay is 0.023 ng/mL and 0.071 ng/mL for the fluorescent signal and the colorimetric signal, respectively. Moreover, the assay was successfully applied to determine sulfadimethoxine in silver carp, shrimp, and lamb samples with satisfactory results.