A highly selective optical probe for sensing of Fe 3+ based on a water-soluble croconaine

Coordinating the mechanism of actions of ferroptosis and photothermal effect for cancer theranostics

Combination therapy based on different mechanisms of cell death has shown promises in tumor therapy. However, design considerations for integrating different modalities are often lack of rationale to synergize the therapeutic effects to the maximal extent. Here, we report a cancer theranostic nanomedicine formula by attentively considering the mechanisms of action of ferroptosis and photothermal effect in combination therapy. We applied the croconaine molecule as both a photothermal converter and an iron-chelating agent which could be readily encapsulated with BSA thus attaining biocompatible and stable Cro-Fe@BSA nanoparticles. The Cro-Fe@BSA nanoprticles in the tumor milieu showed an activated photothermal effect which could enhance the radical formation due to the temperature-dependent Fenton reaction kinetics, while the radical formation during ferroptosis could in turn destruct the heat-induced formation of heat shock proteins, thus preventing the self-protection mechanism of cancer cells in response to heat. This mutually beneficial strategy led to an efficient anticancer effect both in vitro and in a subcutaneous mouse tumor model. Furthermore, the activatable photoacoustic and magnetic resonance imaging performance of the Cro-Fe@BSA nanoparticles provided an intelligent paradigm for safe and reliable cancer theranostics. This study may open up new avenues in designing nanomedicines from a vantage point of synergizing different therapeutic modalities.

Croconaine-based nanoparticles enable efficient optoacoustic imaging of murine brain tumors

Contrast enhancement in optoacoustic (photoacoustic) imaging can be achieved with agents that exhibit high absorption cross-sections, high photostability, low quantum yield, low toxicity, and preferential bio-distribution and clearance profiles. Based on advantageous photophysical properties of croconaine dyes, we explored croconaine-based nanoparticles (CR780RGD-NPs) as highly efficient contrast agents for targeted optoacoustic imaging of challenging preclinical tumor targets. Initial characterization of the CR780 dye was followed by modifications using polyethylene glycol and the cancer-targeting c(RGDyC) peptide, resulting in self-assembled ultrasmall particles with long circulation time and active tumor targeting. Preferential bio-distribution was demonstrated in orthotopic mouse brain tumor models by multispectral optoacoustic tomography (MSOT) imaging and histological analysis. Our findings showcase particle accumulation in brain tumors with sustainable strong optoacoustic signals and minimal toxic side effects. This work points to CR780RGD-NPs as a promising optoacoustic contrast agent for potential use in the diagnosis and image-guided resection of brain tumors.

Facile green synthesis of silicon nanoparticles from Equisetum arvense for fluorescence based detection of Fe(iii) ions

Fluorescent silicon nanoparticles (SiNPs) might be one of the excellent candidates for use as optical markers in biological profiling and diagnostic applications. To exploit this perspective, they ought to be essentially synthesized from any green precursor rich in silicon. Stable dispersibility in water along with prolonged luminescence under different conditions is also desired. Moreover, one of the main challenges is to produce such optically (photoluminescence) stable and water-dispersible SiNPs. In our present work, we have reported the synthesis of a highly stable silicon nanoparticle aqueous suspension via a single-step microwave-assisted facile green route. Our as-prepared SiNPs exhibit inherent stable dispersibility, strong fluorescence, and photo-stable behavior. The experimental results demonstrate that the synthesized SiNPs are highly suitable for the detection of Fe(iii) ions. This optical sensing study opens a new avenue for use of SiNPs as a valuable optical probe in chemosensory applications. Our results provide a single-step methodology for the synthesis of highly stable SiNPs from a biological precursor, which can be used as a promising tool for various chemical and biological applications.