Noninvasive Diagnosis of Kidney Dysfunction Using a Small-Molecule Manganese-Based Magnetic Resonance Imaging Probe

Contrast-enhanced magnetic resonance imaging (CE-MRI) is a promising approach for the diagnosis of kidney diseases. However, safety concerns, including nephrogenic systemic fibrosis, limit the administration of gadolinium (Gd)-based contrast agents (GBCAs) in patients who suffer from renal impairment. Meanwhile, nanomaterials meet biosafety concerns because of their long-term retention in the body. Herein, we propose a small-molecule manganese-based imaging probe Mn-PhDTA as an alternative to GBCAs to assess renal insufficiency for the first time. Mn-PhDTA was synthesized via a simple three-step reaction with a total yield of up to 33.6%, and a gram-scale synthesis can be realized. Mn-PhDTA has an r1 relaxivity of 2.72 mM-1 s-1 at 3.0 T and superior kinetic inertness over Gd-DTPA and Mn-EDTA with a dissociation time of 60 min in the presence of excess Zn2+. In vivo and in vitro experiments demonstrate their good stability and biocompatibility. In the unilateral ureteral obstruction rats, Mn-PhDTA provided significant MR signal enhancement, enabled distinguishing structure changes between the normal and damaged kidneys, and evaluated the renal function at different injured stages. Mn-PhDTA could act as a potential MRI contrast agent candidate for the replacement of GBCAs in the early detection of kidney dysfunction and analysis of kidney disease progression.

Topology-regulated nanocatalysts for ferroptosis-mediated cancer phototherapy

Ferroptosis-mediated tumor treatment is constrained by the absence of single-component, activatable multifunctional inducers. Given this, a topological synthesis strategy is employed to develop an efficient bismuth-based semiconductor nano-photocatalyst (Bi2O3:S) for tumor ferroptosis therapy. Photo-excited electrons can participate in the reduction reaction to produce harmful reactive oxygen species (ROS) when exposed to near-infrared light. Meanwhile, photo-excited holes can contribute to the oxidation reaction to utilize extra glutathione (GSH) in tumors. In the acidic tumor microenvironment, bismuth ions generated from Bi2O3:S may further cooperate with GSH to amplify oxidative stress damage and achieve biodegradation. Both promote ferroptosis by downregulating glutathione peroxidase 4 (GPX4) expression. Besides, sulfur doping optimizes its near-infrared light-induced photothermal conversion efficiency, benefiting its therapeutic effect. Thus, bismuth ions and holes synergistically drive photo-activable ferroptosis in this nanoplatform, opening up new avenues for tumor therapy.

Recent Developments of Inorganic Nanosensitizers for Sonodynamic Therapy

As a noninvasive treatment, sonodynamic therapy (SDT) has been widely used in the treatment of tumors because of its ability to penetrate deep tissue with few side effects. As the key factor of SDT, it is meaningful to design and synthesize efficient sonosensitizers. Compared with organic sonosensitizers, inorganic sonosensitizers can be easily excited by ultrasound. In addition, inorganic sonosensitizers with stable properties, good dispersion, and long blood circulation time, have great development potential in SDT. This review summarizes possible mechanisms of SDT (sonoexcitation and ultrasonic cavitation) in detail. Based on these mechanisms, the design and synthesis of inorganic nanosonosensitizers can be divided into three categories: traditional inorganic semiconductor sonosensitizers, enhanced inorganic semiconductor sonosensitizers, and cavitation-enhanced sonosensitizers. Subsequently, the current efficient construction methods of sonosensitizers are summarized including accelerated semiconductor charge separation and enhanced production of reactive oxygen species through ultrasonic cavitation. Furthermore, the advantages and disadvantages of different inorganic sonosensitizers and detailed strategies are systematically discussed on how to enhance SDT. Hopefully, this review could provide new insights into the design and synthesis of efficient inorganic nano-sonosensitizers for SDT.

Lanthanide-doped bismuth-based nanophosphors for ratiometric upconversion optical thermometry

Nanothermometry could realize stable, efficient, and noninvasive temperature detection at the nanoscale. Unfortunately, most applications of nanothermometers are still limited due to their intricate synthetic process and low-temperature sensitivity. Herein, we reported a kind of novel bismuth-based upconversion nanomaterial with a fast and facile preparation strategy. The bismuth-based upconversion luminophore was synthesized by the co-precipitation method within 1 minute. By optimizing the doping ratio of the sensitizer Yb ion and the activator Er ion and adjusting the synthetic solvent strategy, the crystallinity of the nanomaterials was increased and the upconversion luminescence intensity was improved. Ratiometric upconversion optical measurements of temperature in the range of 278 K to 358 K can be achieved by ratiometric characteristic emission peaks of thermally sensitive Er ion. This method of rapidly constructing nanometer temperature probes provides a feasible strategy for the construction of novel fluorescent temperature probes.

Lanthanide-doped bismuth-based nanospheres can be rapidly synthesized within 1 minute for upconversion luminescence ratiometric temperature detection.