Size-changeable nanoprobes for the combined radiotherapy and photodynamic therapy of tumor

Upconverting Ultra-Thin Bi2O2CO3 Nanosheets for Synergistic Photodynamic Therapy and Radiotherapy

Synergistic therapy has become the major therapeutic method for malignant tumors in clinical. Photodynamic therapy (PDT) and radiotherapy (RT) always combine together because of their identical anti-tumor mechanisms, that is reactive oxygen species are generated by the use of radiosensitizers after irradiation by X-ray to efficiently kill cancer cells, PDT also follows similar mechanism. Full exposure of energy-absorbing species in nanomaterials to X-ray or near-infrared light irradiation makes the energy interchange between nanomaterials and surrounding H2O or dissolved oxygen easier, however, it remains challenging. Herein, an ultrathin two-dimensional (2D) nanosheet (NS) is developed, Bi2O2CO3, doped with lanthanide ions to give out upconversion luminescence, where the high Z elements Bi, Yb, and Er promote the radio-sensitizing effect. To the surprise, lanthanide activator ions gave out completely different luminescence properties compared with traditional upconversion nanoparticles. Less dopant of Er ions in nanosheets lattice resulted in brighter red emission, which provides more efficient PDT. Under RT/PDT combined treatment, NS shows a good tumor growth-inhibiting effect. In addition, synergistic therapy requires lower radiation dose than conventional radiotherapy and lower light power than single photodynamic therapy, thus greatly reducing radiation damage caused by RT and thermal damage caused by PDT.

Intercalating of AIEgens into MoS2 nanosheets to induce crystal phase transform for enhanced photothermal and photodynamic synergetic anti-tumor therapy

A MoS2-based nanotherapeutic platform was developed for synergetic photothermal and photodynamic anti-tumor therapy. AIEgens TFPy-SH molecules were intercalated into MoS2 nanosheets (MoS2 NSs) with S-deficiencies to give the nanocomposite MoS2-TFPy. The AIEgens intercalation expanded the interlayer spacing of MoS2 NSs and induced the transform of MoS2 crystal phase from 2H to 1T, offering MoS2-TFPy nanocomposite high molar absorption coefficient (5.65 L g-1 cm-1), excellent photothermal conversion efficiency under near-infrared (NIR) laser irradiation (38.3%), and favorable intracellular reactive oxygen species (ROS) generation capacity. The positively charged MoS2-TFPy were mainly distributed in mitochondria after cell up-taking, and achieved 1+1>2 anti-tumor effect attributed to its favorable photothermal and photodynamic properties. The high structure and physiological stability, favorable biocompatibility, excellent photothermal and photodynamic therapy effect make the MoS2-TFPy nanoplatform an promising candidate in biomedical clinical applications.

Imaging and monitoring of granzyme B in the immune response

Significant progress has been made in tumor immunotherapy that uses the human immune response to kill and remove tumor cells. However, overreactive immune response could lead to various autoimmune diseases and acute rejection. Accurate and specific monitoring of immune responses in these processes could help select appropriate therapies and regimens for the patient and could reduce the risk of side effects. Granzyme B (GzmB) is an ideal biomarker for immune response, and its peptide substrate could be coupled with fluorescent dyes or contrast agents for the synthesis of imaging probes activated by GzmB. These small molecules and nanoprobes based on PET, bioluminescence imaging, or fluorescence imaging have proved to be highly GzmB specific and accuracy. This review summarizes the design of different GzmB-responsive imaging probes and their applications in monitoring of tumor immunotherapy and overreactive immune response. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging.

Preclinical Evaluation of a Protein-Based Nanoscale Contrast Agent for MR Angiography at an Ultralow Dose

PURPOSE

BSA-biomineralized Gd nanoparticles (Gd@BSA NPs) have been recognized as promising nanoscale MR contrast agents. The aim of this study was to carry out a preclinical evaluation of these NPs in a middle-sized animal model (rabbits).

METHODS

New Zealand white rabbits were treated intravenously with Gd@BSA NPs (0.02 mmol Gd/kg) via a clinically-used high-pressure injector, with commercial Gd-diethylene triamine pentaacetate (Gd-DTPA)-injected group as control. Then MR angiography was performed according to the standard clinical protocol with a 3.0-T MR scanner. The SNR and CNR of the main arteries and branches were monitored. Pharmacokinetics and bioclearance were continuously evaluated in blood, urine, and feces. Gd deposition in vital organs was measured by ICP‒MS. Weight monitoring, HE staining, and blood biochemical analysis were also performed to comprehensively estimate systemic toxicity.

RESULTS

The ultrasmall Gd@BSA NPs (<6 nm) exhibited high stability and T1 relaxivity. Compared to Gd-DTPA, Gd@BSA NPs demonstrated superior vascular system imaging performance at ultralow doses, especially of the cardiac artery and other main branches, and exhibited a significantly higher SNR and CNR. Notably, the Gd@BSA NPs showed a shorter half-life in blood, less retention in organs, and improved biocompatibility.

CONCLUSION

The preclinical evaluations here demonstrated that Gd@BSA NPs are promising and advantageous MR CA candidates that can be used at a low dose with excellent MR imaging performance, thus suggesting its further clinical trials and applications.

Transformable nanodrugs for overcoming the biological barriers in the tumor environment during drug delivery

Drug delivery systems have been studied massively with explosive growth in the last few decades. However, challenges such as biological barriers are still obstructing the delivery efficiency of nanomedicines. Reports have shown that the physicochemical properties, such as the morphologies of nanodrugs, could highly affect their biodistribution and bioavailability. Therefore, transformable nanodrugs that take advantage of different sizes and shapes allow for overcoming multiple biological barriers, providing promising prospects for drug delivery. This review aims to present an overview of the most recent developments of transformable nanodrugs in this emerging field. First, the design principles and transformation mechanisms which serve as guidelines for smart nanodrugs are summarized. Afterward, their applications in overcoming biological barriers, including the bloodstream, intratumoral pressure, cellular membrane, endosomal wrapping, and nuclear membrane, are highlighted. Finally, discussions on the current developments and future perspectives of transformable nanodrugs are given.

Hypoxia-Responsive Aggregation of Gold Nanoparticles for Near-Infrared-II Photoacoustic Imaging-Guided Enhanced Radiotherapy

By directly harming cancer cells, radiotherapy (RT) is a crucial therapeutic approach for the treatment of cancers. However, the efficacy of RT is reduced by the limited accumulation and short retention time of the radiosensitizer in the tumor. Herein, we developed hypoxia-triggered in situ aggregation of nanogapped gold nanospheres (AuNNP@PAA/NIC NPs) within the tumor, resulting in second near-infrared window (NIR-II) photoacoustic (PA) imaging and enhanced radiosensitization. AuNNP@PAA/NIC NPs demonstrated increased accumulation and retention in hypoxic tumors, mainly due to the hypoxia-triggered aggregation. After aggregation of AuNNP@PAA/NIC NPs, the absorption of the system extended from visible light to NIR-II light owing to the plasmon coupling effects between adjacent nanoparticles. Compared to the normoxic tumor, the PA intensity at 1200 nm in the hypoxic tumor increased from 0.42 to 1.88 at 24 h postintravenous injection of AuNNP@PAA/NIC NPs, leading to an increase of 4.5 times. This indicated that the hypoxic microenvironment in the tumor successfully triggered the in situ aggregation of AuNNP@PAA/NIC NPs. The in vivo radiotherapeutic effect demonstrated that this hypoxia-triggered in situ aggregation of radiosensitizers significantly enhanced radiosensitization and thus resulted in superior cancer radiotherapeutic outcomes.

Catalytic nanotechnology of X-ray photodynamics for cancer treatments

Photodynamic therapy (PDT) has been applied in cancer treatment because of its high selectivity, low toxicity, and non-invasiveness. However, the limited penetration depth of the light still hampers from reaching deep-seated tumors. Considering the penetrating ability of high-energy radiotherapy, X-ray-induced photodynamic therapy (X-PDT) has evolved as an alternative to overcome tissue blocks. As the basic principle of X-PDT, X-rays stimulate the nanoparticles to emit scintillating or persistent luminescence and further activate the photosensitizers to generate reactive oxygen species (ROS), which would cause a series of molecular and cellular damages, immune response, and eventually break down the tumor tissue. In recent years, catalytic nanosystems with unique structures and functions have emerged that can enhance X-PDT therapeutic effects via an immune response. The anti-cancer effect of X-PDT is closely related to the following factors: energy conversion efficiency of the material, the radiation dose of X-rays, quantum yield of the material, tumor resistance, and biocompatibility. Based on the latest research in this field and the classical theories of nanoscience, this paper systematically elucidates the current development of the X-PDT and related immunotherapy, and highlights its broad prospects in medical applications, discussing the connection between fundamental science and clinical translation.

Innovative strategies for photodynamic therapy against hypoxic tumor

Photodynamic therapy (PDT) is applied as a robust therapeutic option for tumor, which exhibits some advantages of unique selectivity and irreversible damage to tumor cells. Among which, photosensitizer (PS), appropriate laser irradiation and oxygen (O₂) are three essential components for PDT, but the hypoxic tumor microenvironment (TME) restricts the O₂ supply in tumor tissues. Even worse, tumor metastasis and drug resistance frequently happen under hypoxic condition, which further deteriorate the antitumor effect of PDT. To enhance the PDT efficiency, critical attention has been received by relieving tumor hypoxia, and innovative strategies on this topic continue to emerge. Traditionally, the O₂ supplement strategy is considered as a direct and effective strategy to relieve TME, whereas it is confronted with great challenges for continuous O₂ supply. Recently, O₂-independent PDT provides a brand new strategy to enhance the antitumor efficiency, which can avoid the influence of TME. In addition, PDT can synergize with other antitumor strategies, such as chemotherapy, immunotherapy, photothermal therapy (PTT) and starvation therapy, to remedy the inadequate PDT effect under hypoxia conditions. In this paper, we summarized the latest progresses in the development of innovative strategies to improve PDT efficacy against hypoxic tumor, which were classified into O₂-dependent PDT, O₂-independent PDT and synergistic therapy. Furthermore, the advantages and deficiencies of various strategies were also discussed to envisage the prospects and challenges in future study.

The multifunctional Prussian blue/graphitic carbon nitride nanocomposites for fluorescence imaging-guided photothermal and photodynamic combination therapy

Cancer has been regarded as one of the most intractable diseases worldwide and threatens human health and life. Photothermal/Photodynamic therapy (PTT and PDT) have emerged as reliable and effective strategies in cancer treatment with the superiorities of non-invasiveness, slight side effects, and high treatment efficiency. Herein, a nanocomposite (PBCN) was fabricated via electrostatic interaction between Prussian blue nanoparticles (PBNPs) and graphitic carbon nitride (g-C3N4), and the resulting PBCN possessed good photothermal properties and excellent photodynamic effects with 808 nm irradiation. Furthermore, it exhibits excellent fluorescence imaging ability in cells, highlighting its potential as a powerful imaging agent in the biomedical field. Combination with a photothermal material, photosensitizer, and fluorescence imaging agent would thus allow PBCN to realize fluorescence imaging-guided PTT/PDT, showing an outstanding theranostic effect on cancer cells.