Ultrasmall porphyrin-silica core-shell dots for enhanced fluorescence imaging-guided cancer photodynamic therapy

Photodynamic therapy with NIR-II probes: review on state-of-the-art tools and strategies

In 2022 10% of the world's population was aged 65+, and by 2100 this segment is expected to hit 25%. These demographic changes place considerable pressure over healthcare systems worldwide, which results in an urgent need for accurate, inexpensive and non-invasive ways to treat cancers, a family of diseases correlated with age. Among the therapeutic tools that gained important attention in this context, photodynamic therapies (PDT), which use photosensitizers to produce cytotoxic substances for selectively destroying tumor cells and tissues under light irradiation, profile as important players for next-generation nanomedicine. However, the development of clinical applications is progressing at slow pace, due to still pending bottlenecks, such as the limited tissue penetration of the excitation light, and insufficient targeting performance of the therapeutic probes to fully avoid damage to normal cells and tissues. The penetration depth of long-wavelength near infrared (NIR) light is significantly higher than that of short-wavelength UV and visible light, and thus NIR light in the second window (NIR-II) is acknowledged as the preferred phototherapeutic means for eliminating deep-seated tumors, given the higher maximum permissible exposure, reduced phototoxicity and low autofluorescence, among others. Upon collective multidisciplinary efforts of experts in materials science, medicine and biology, multifunctional NIR-II inorganic or organic photosensitizers have been widely developed. This review overviews the current state-of-the art on NIR-II-activated photosensitizers and their applications for the treatment of deep tumors. We also place focus on recent efforts that combine NIR-II activated PDT with other complementary therapeutic routes such as photothermal therapy, chemotherapy, immunotherapy, starvation, and gas therapies. Finally, we discuss still pending challenges and problems of PDT and provide a series of perspectives that we find useful for further extending the state-of-the art on NIR-II-triggered PDT.

Multifunctional siRNA/ferrocene/cyclodextrin nanoparticles for enhanced chemodynamic cancer therapy

The therapeutic outcome of chemodynamic therapy (CDT) is greatly hindered by the presence of oxidative damage repair proteins (MTH1) inside cancer cells. These oxidative damage repair proteins detoxify the action of radicals generated by Fenton or Fenton-like reactions. Hence, it is extremely important to develop a simple strategy for the downregulation of MTH1 protein inside cancer cells along with the delivery of metal ions into cancer cells. A one-pot host-guest supramolecular approach for the codelivery of MTH1 siRNA and metal ions into a cancer cell is reported. Our approach involves the fabrication of an inclusion complex between cationic β-cyclodextrin and a ferrocene prodrug, which spontaneously undergoes amphiphilicity-driven self-assembly to form spherical nanoparticles (NPs) having a positively charged surface. The cationic surface of the NPs was then explored for the loading of MTH1 siRNA through electrostatic interactions. Using HeLa cells as a representative example, efficient uptake of the NPs, delivery of MTH1 siRNA and the enhanced CDT of the nanoformulation are demonstrated. This work highlights the potential of the supramolecular approach as a simple yet efficient method for the delivery of siRNA across the cell membrane for enhanced chemodynamic therapy.

Unleashing the power of porphyrin photosensitizers: Illuminating breakthroughs in photodynamic therapy

This comprehensive review provides the current trends and recent developments of porphyrin-based photosensitizers. We discuss their evolution from first-generation to third-generation compounds, including cutting-edge nanoparticle-integrated derivatives, and explores their pivotal role in advancing photodynamic therapy (PDT) for enhanced cancer treatment. Integrating porphyrins with nanoparticles represents a promising avenue, offering improved selectivity, reduced toxicity, and heightened biocompatibility. By elucidating recent breakthroughs, innovative methodologies, and emerging applications, this review provides a panoramic snapshot of the dynamic field, addressing challenges and charting prospects. With a focus on harnessing reactive oxygen species (ROS) through light activation, PDT serves as a minimally invasive therapeutic approach. This article offers a valuable resource for researchers, clinicians, and PDT enthusiasts, highlighting the potential of porphyrin photosensitizers to improve the future of cancer therapy.

Water-soluble phthalocyanine photosensitizers for photodynamic therapy

Photodynamic therapy (PDT) is based on a photochemical reaction that is started when a photosensitizing process is activated by the light and results in the death of tumor cells. Solubility is crucial in PDT applications to investigate the physical and chemical characteristics of phthalocyanines, but, unfortunately, most phthalocyanines show limited solubility especially in water. To increase the solubility of phthalocyanines in polar solvents and water, ionic groups such as -SO3-, -NR3+, -COO-, and nonionic groups such as polyoxy chains are frequently added to the peripheral or nonperipheral positions of the phthalocyanine framework. Since water-solubility and NIR-absorbing properties are essential for efficient PDT activation, studies have been focused on the synthesis of these types of phthalocyanine derivatives. This review focuses on the photophysical, photochemical, and some in vitro or in vivo studies of the recently published ionic and nonionic phthalocyanine-mediated photosensitizers carried out in the last five years. This review will have positive contributions to future studies on phthalocyanine chemistry and their PDT applications as well as photochemistry.

Quercetin@Gd3+ doped Prussian blue nanocubes induce the pyroptotic death of MDA-MB-231 cells: combinational targeted multimodal therapy, dual modal MRI, intuitive modelling of r1-r2 relaxivities

Quercetin (Qu), a potential bioflavonoid has gained considerable interest as a promising chemotherapeutic drug which can inhibit the proliferation of triple-negative breast cancer (TNBC) cells due to its regulation of the expression of tumor-suppressor gene metastasis and antioxidant property. Notably, Qu exhibits a very negligible cytotoxic effect on normal cells, even with high-dose treatment, while it is shows high affinity to TNBC. However, the efficiency of Qu is limited clinically due to its poor bioavailability, caused by its low aqueous solubility (2.15 μg mL^-1 at 25 °C), rapid gastrointestinal digestion and chemical instability in alkaline and neutral media. Herein, polydopamine (PDA)-coated, NH₂-PEG-NH₂ and hyaluronic acid (HA)-functionalized Gd³⁺-doped Prussian blue nanocubes (GPBNC) are reported as a multifunctional platform for the codelivery of Qu as a chemotherapeutic agent and GPBNC as a photodynamic (PDT) and photothermal (PTT) agent with improved therapeutic efficiency to overcome theses barriers. PDA, NH₂-PEG-NH₂ and HA stabilize GPBNC@Qu and facilitate bioavailability and active-targeting, while absorption of near infrared (NIR) (808 nm; 1 W cm^-2) induces PDT and PTT activities and dual T₁-T₂-weighted magnetic resonance imaging (MRI) with high relaxometric parameters (r₁ 10.06 mM^-1 s^-1 and r₂ 24.96 mM^-1 s^-1 at a magnetic field of 3 T). The designed platform shows a pH-responsive Qu release profile and NIR-induced therapeutic efficiency of ∼79% in 20 minutes of irradiation, wherein N-terminal gardermin D (N-GSDMD) and a P2X7-receptor-mediated pyroptosis pathway induces cell death, corroborating the up-regulation of NLRP3, caspase-1, caspase-5, N-GSDMD, IL-1β, cleaved Pannexin-1 and P2X7 proteins. More interestingly, the increasing relaxivity values of Prussian blue nanocubes with Gd³⁺ doping have been explained on the basis of Solomon-Bloembergen-Morgan theory, considering inner- and outer-sphere relaxivity, wherein crystal defects, coordinated water molecules, tumbling rate, metal to water proton distance, correlation time, magnetisation value etc. play a significant role. In summary, our study suggests that GPBNC could be a beneficial nanocarrier for theranostic purposes against TNBC, while our conceptual study clearly demonstrates the role of various factors in increasing relaxometric parameters.