In vivo static and dynamic angiography of thrombosis by using multi-functional lanthanide nanoprobes

Reducing Chemo-/Radioresistance to Boost the Therapeutic Efficacy against Temozolomide-Resistant Glioblastoma

Chemo-/radioresistance is the most important reason for the failure of glioblastoma (GBM) treatment. Reversing the chemo-/radioresistance of GBM for boosting therapeutic efficacy is very challenging. Herein, we report a significant decrease in the chemo-/radioresistance of GBM by the in situ generation of SO₂ within a tumor, which was released on demand from the prodrug 5-amino-1,3-dihydrobenzo[c]thiophene 2,2-dioxide (ATD) loaded on rare-earth-based scintillator nanoparticles (i.e., NaYF₄:Ce@NaLuF₄:Nd@ATD@DSPE-PEG₅₀₀₀, ScNPs) under X-ray irradiation. Our novel X-ray-responsive ScNPs efficiently converted highly penetrating X-rays into ultraviolet rays for controlling the decomposition of ATD to generate SO₂, which effectively damaged the mitochondria of temozolomide-resistant U87 cells to lower the production of ATP and inhibit P-glycoprotein (P-gp) expression to reduce drug efflux. Meanwhile, the O⁶-methylguanine-DNA methyltransferase (MGMT) of drug-resistant tumor cells was also reduced to prevent the repair of damaged DNA and enhance cell apoptosis and the efficacy of chemo-/radiotherapy. The tumor growth was obviously suppressed, and the mice survived significantly longer than untreated temozolomide-resistant GBM-bearing mice. Our work demonstrates the potential of SO₂ in reducing chemo-/radioresistance to improve the therapeutic effect against resistant tumors if it can be well controlled and in situ generated in tumor cells. It also provides insights into the rational design of stimuli-responsive drug delivery systems for the controlled release of drugs.

Boosting Vascular Imaging-Performance and Systemic Biosafety of Ultra-Small NaGdF4 Nanoparticles via Surface Engineering with Rationally Designed Novel Hydrophilic Block Co-Polymer

Revealing the anatomical structures, functions, and distribution of vasculature via contrast agent (CA) enhanced magnetic resonance imaging (MRI) is crucial for precise medical diagnosis and therapy. The clinically used MRI CAs strongly rely on Gd-chelates, which exhibit low T₁ relaxivities and high risks of nephrogenic systemic fibrosis (NSF) for patients with renal dysfunction. It is extremely important to develop high-performance and safe CAs for MRI. Herein, it is reported that ultra-small NaGdF₄ nanoparticles (UGNs) can serve as an excellent safe MRI CA via surface engineering with rationally designed novel hydrophilic block co-polymer (BP_n ). By optimizing the polymer molecular weights, the polymer-functionalized UGNs (i.e., UGNs-BP₁₄ ) are obtained to exhibit remarkably higher relaxivity (11.8 mm^-1 s^-1 at 3.0 T) than Gd-DTPA (3.6 mm^-1 s^-1 ) due to their ultracompact and abundant hydrophilic surface coating. The high performance of UGNs-BP₁₄ enables us to sensitively visualize microvasculature with a small diameter of ≈0.17 mm for up to 2 h, which is the thinnest blood vessel and the longest time window for low field (1.0 T) MR angiography ever reported, and cannot be achieved by using the clinically used Gd-DTPA under the same conditions. More importantly, renal clearable UGNs-BP₁₄ show lower risks of inducing NSF in comparison with Gd-DTPA due to their negligible release of Gd³⁺ ions after modification with the novel hydrophilic block copolymer. The study presents a novel avenue for boosting imaging-performance and systemic biosafety of UGNs as a robust MRI CA with great potential in precise diagnosis of vasculature-related diseases.