Biomedical Application of Porphyrin-Based Amphiphiles and Their Self-Assembled Nanomaterials

Multifunctional porphyrin-substituted phenylalanine-phenylalanine nanoparticles for diagnostic and therapeutic applications in Alzheimer's disease

β-Amyloid (Aβ) peptides are believed as the diagnostic biomarkers and therapeutic targets of Alzheimer's disease (AD). Their complexes with copper ions can catalyze the generation of reactive oxygen species (ROS) to further promote neuronal death. Herein, we suggested that porphyrin-substituted phenylalanine-phenylalanine nanoparticles (TPP-FF NPs) could inhibit the aggregation of Aβ monomers, disassemble the fibrillar Aβ aggregates under light illumination, and depressing the Cu2+-induced generation of ROS. Meanwhile, the TPP-FF NPs could be used as the nanocarriers and quenchers of fluorescently-labeled probes for the detection of Aβ oligomer (AβO). Inhibition of Aβ assembly and dissolution of Aβ aggregates were monitored by Thioflavin T (ThT)-based fluorescent assay and characterized by atomic force microscopy. The Aβ/Cu2+-induced generation of ROS was limited by TPP-FF NPs. The fluorescein-labeled probe aptamers attached on the surface of TPP-FF NPs emitted low fluorescence. The interaction between AβO and aptamers induced the release of the probes from the surface of TPP-FF NPs, driving the fluorophore far away from the quenchers and turning on the fluorescence. The signal-on strategy can be used for the detection of AβO with a low detection limit. This work should be evaluable for the development of multifunctional candidates for the diagnosis and treatment of AD.

Research progress of nitroxide radical-based MRI contrast agents: from structure design to application

Magnetic resonance imaging (MRI) remains a cornerstone of diagnostic imaging, offering unparalleled insights into anatomical structures and pathological conditions. Gadolinium-based contrast agents have long been the standard in MRI enhancement, yet concerns over nephrogenic systemic fibrosis have spurred interest in metal-free alternatives. Nitroxide radical-based MRI contrast agents (NO-CAs) have emerged as promising candidates, leveraging their biocompatibility and imaging capabilities. This review summaries the latest advancements in NO-CAs, focusing on synthesis methodologies, influencing effects of structures of NO-CAs on relaxation efficiency and their applications across various clinical contexts. Comprehensive discussions encompass small molecular, polymeric, and nano-sized NO-CAs, detailing their unique properties and potential clinical utilities. Despite challenges, NO-CAs represent a dynamic area of research poised to revolutionize MRI diagnostics. This review serves as a critical resource for researchers and practitioners seeking to navigate the evolving landscape of MRI contrast agents.

Enhancing Targeted Photodynamic Therapy: Star-Shaped Glycopolymeric Photosensitizers for Improved Selectivity and Efficacy

Targeted photodynamic therapy (PDT) offers advantages over nontargeted approaches, including improved selectivity, efficacy, and reduced side effects. This study developed star-shaped glycopolymeric photosensitizers using porphyrin-based initiators via ATRP. Incorporating a porphyrin core gave the polymers fluorescence and ROS generation, while adding fructose improved solubility and targeting capabilities. The photosensitizers had high light absorption, singlet oxygen production, specificity, low dark toxicity, and biocompatibility. The glycopolymers with longer sugar arms and higher density showed better uptake on MCF-7 and MDA-MB-468 cells compared to HeLa cells, indicating enhanced targeting capabilities. Inhibition of endocytosis confirmed the importance of the GLUT5 receptor. The resulting polymers exhibited good cytocompatibility under dark conditions and satisfactory PDT under light irradiation. Interestingly, the polymers containing fructose have a GLUT5-dependent elimination effect on the MCF-7 and MDA-MB-468 cells. The intracellular ROS production followed a similar pattern, indicating that the fructose polymer exhibits specific targeting toward cells with GLUT5 receptors.