Ultrasmall Platinum Research Articles

Ultra-small platinum nano-enzymatic spray with ROS scavenging and anti-inflammatory properties for photoaging treatment

Photoaging induced by ultraviolet (UV) results in oxidative stress and inflammation. Noble metal nanozymes have strong antioxidant and anti-inflammatory capacity, which are expected to eliminate the excessive reactive oxygen species (ROS) and inflammatory factors in the photoaged skin. Hence, we have synthesized ultrasmall platinum nanoparticles coated with polyvinylpyrrolidone (Pt NPs) with a diameter of nearly 5 nm for photoaging treatment. Thanks to multi-enzymatic capacities (catalase, peroxidase, and superoxide dismutase) of Pt NPs, they can effectively protect fibroblasts from UV-induced ROS attack, relieve fibroblasts from UV-induced cell cycle arrest, downregulate matrix metalloproteinases (MMPs) to regenerate type I collagen, and inhibit M1 macrophage polarization to decrease the expression of inflammatory factors. For photoaged mice treatment, we employ the concept of routine spray skincare and encapsulate Pt NPs solution in a spray bottle. In combination with roller needle, following Pt NPs nano-enzymatic spray given, UV-induced photoaged mice display reduced wrinkle formation in the collagen-depleted dermal tissue of mice and more youthful performance in both appearance and organizational structure. Consequently, multi-enzymatic functions of Pt NPs nano-spray offers a promising avenue for anti-photoaging therapy, providing potential benefits in both preventative and restorative skincare applications.

High-performance electrocatalyst for PEMFC cathode: Combination of ultra-small platinum nanoparticles and N-doped carbon support

To accelerate the implementation of zero-emission power installations based on proton-exchange membrane fuel cells, it is necessary to maximize the power characteristics of these devices. For this purpose, we have obtained and tested a new N-doped carbon support and a synthesized Pt/C catalyst based on it with a platinum loading of about 37.3 %. A comparison of the degradation resistance of the initial support and the N-doped one has shown greater stability of the latter. At the same time, Raman spectroscopy has confirmed the presence of the C–N bond, which indicates the successful doping of carbon with nitrogen. The resulting Pt/C catalyst based on an N-doped support is characterized by a substantially narrow size dispersion and an ultra-small nanoparticle size of about 2.6 nm. The high-angle annular dark-field scanning transmission electron microscopy images of the synthesized catalyst have confirmed the presence of individual platinum atoms/clusters uniformly distributed over the surface of the support, and their presence is due to nitrogen embedded into the carbon structure. This material is characterized by a 50 m2 gPt-1 larger electrochemically active surface area and a 227 A gPt-1 greater mass activity compared to the commercial JM40 analog (40 % platinum loading). Meanwhile, the electrochemical parameters remaining after the accelerated stress testing are almost 2 times higher than those of JM40. And the power characteristics in the membrane electrode assembly for the catalyst synthesized by the facile one-pot synthesis method are 13 % (575 mW cm-2) higher than those of the commercial analog (500 mW cm-2). The Pt/C catalyst obtained during the research is deemed promising for commercial use in proton-exchange membrane fuel cells.

PH-Activatable Pre-Nanozyme Mediated H2S Delivery for Endo-Exogenous Regulation of Oxidative Stress in Acute Kidney Injury.

Oxidative stress induced by excess reactive oxygen species (ROS) is a primary pathogenic cause of acute kidney injury (AKI). Development of an effective antioxidation system to mitigate oxidative stress for alleviating AKI remains to be investigated. This study presents the synthesis of an ultra-small Platinum (Pt) sulfur cluster (Pt5.65S), which functions as a pH-activatable prefabricated nanozyme (pre-nanozyme). This pre-nanozyme releases hydrogen sulfide (H2S) and transforms into a nanozyme (Ptzyme) that mimics various antioxidant enzymes, including superoxide dismutase and catalase, within the inflammatory microenvironment. Notably, the Pt5.65S pre-nanozyme exhibits an endo-exogenous synergy-enhanced antioxidant therapeutic mechanism. The Ptzyme reduces oxidative damage and inflammation, while the released H2S gas promotes proneurogenesis by activating Nrf2 and upregulating the expression of antioxidant molecules and enzymes. Consequently, the Pt5.65S pre-nanozyme showscytoprotective effects against ROS/reactive nitrogen species (RNS)-mediated damage at remarkably low doses, significantly improving treatment efficacy in mouse models of kidney ischemia-reperfusion injury and cisplatin-induced AKI. Based on these findings, the H2S-generating pre-nanozyme may represent a promising therapeutic strategy for mitigating inflammatory diseases such as AKI and others.

Ultrasmall platinum nanoclusters: A potent chemotherapeutic drug for cancer-specific DNA damage with optimizing therapeutic efficacy while minimizing systemic toxicity

Platinum chemotherapy drugs, represented by cisplatin, have been widely used in cancer therapy. While they are effective, their use is limited by their adverse effects in long-term administration, especially the lack of selectivity and high systemic toxicity. Encouragingly, molecular-like platinum nanoclusters, as a bridge between nanomedical and small molecular drugs, provide an attractive opportunity to completely change the current status of cancer treatment, mainly due to their unique structural advantages, making them highly efficient and low toxic. Functional modifications offer a promising avenue to enhance template-modified platinum nanoclusters' selectivity and safety, addressing systemic toxicity concerns. Concurrently, leveraging tumor heterogeneity facilitates drug bioactivity via metabolism, thereby augmenting therapeutic efficacy. Herein, we utilized iRGD-modified bovine serum albumin (BSA-iRGD) as the protective molecule to construct platinum nanoclusters drug (PtNC@BSA-iRGD) directly under mild conditions. The new type of chemotherapeutic drug PtNC@BSA-iRGD exhibits excellent antitumor activity in vitro/vivo, in comparison to clinical commercial first-line carboplatin. This powerful antitumor effect is attributed to its selective uptake by tumor cells through receptor-mediated endocytosis. The release of platinum ions inhibits DNA replication by forming DNA-Pt complexes, activates apoptosis pathways, and ultimately induces tumor cell apoptosis. More impressively, compared to first-line platinum chemotherapy drugs, PtNC@BSA-iRGD has superior biocompatibility while possessing higher tumor inhibitory activity in vivo during medication treatment. This feature compensates for the shortcomings of clinical chemotherapy platinum-based drugs. This study provides novel insights into exploring new forms of metal cluster-based platinum drugs with high efficiency for optimizing therapeutic efficacy while minimizing systemic toxicity.

Photothermal-promoted O2/[rad]OH generation of gold nanotetrapod @ platinum nano-islands for enhanced catalytic/photodynamic therapy

Ultrasmall platinum (Pt) nanozymes are used for catalytic therapy and oxygen (O2)-dependent photodynamic therapy (PDT) by harnessing the dual-enzyme activities of catalase (CAT) and peroxidase (POD). However, their applications as nanocatalysts are limited due to their low catalytic activity. Herein, we constructed a photothermal-promoted bimetallic nanoplatform (AuNTP@Pt-IR808) by depositing ultrasmall Pt nano-islands and modifying 1-(5-Carboxypentyl)-2-(2-(3-(2-(1-(5-carboxypentyl)-3,3-dimethylindolin-2-ylidene)ethylidene)-2-chlorocyclohex-1-en-1-yl)vinyl)-3,3-dimethyl-3H-indol-1-ium bromide (IR808) on gold nanotetrapod (AuNTP) with CAT/POD activities to enhance PDT/catalytic therapy. In the tumor microenvironment, the ultrasmall Pt can catalyze endogenous hydrogen peroxide (H2O2) to produce O2, relieving tumor hypoxia and enhancing the PDT performance. Moreover, AuNTP integration into the bimetallic nanoplatform showed good electron transfer properties and promoted the POD activity of ultrasmall Pt. Importantly, AuNTP@Pt-IR808 possessed higher photothermal conversion performance than single AuNTPs, which enhanced photothermal therapy (PTT). It also accelerated the CAT/POD dual-enzyme activities, and promoted the generation of singlet oxygen (1O2) and hydroxyl radical (OH). By enhancing the performances of PTT/PDT/catalytic therapy, the developed AuNTP@Pt-IR808 nanoplatform demonstrated good antitumor efficacy against breast cancer.

Chiral metal-organic frameworks incorporating nanozymes as neuroinflammation inhibitors for managing Parkinson’s disease

Nanomedicine-based anti-neuroinflammation strategy has become a promising dawn of Parkinson’s disease (PD) treatment. However, there are significant gaps in our understanding of the therapeutic mechanisms of antioxidant nanomedicines concerning the pathways traversing the blood-brain barrier (BBB) and subsequent inflammation mitigation. Here, we report nanozyme-integrated metal-organic frameworks with excellent antioxidant activity and chiral-dependent BBB transendocytosis as anti-neuroinflammatory agents for the treatment of PD. These chiral nanozymes are synthesized by embedding ultra-small platinum nanozymes (Ptzymes) into L-chiral and D-chiral imidazolate zeolite frameworks (Ptzyme@L-ZIF and Ptzyme@D-ZIF). Compared to Ptzyme@L-ZIF, Ptzyme@D-ZIF shows higher accumulation in the brains of male PD mouse models due to longer plasma residence time and more pathways to traverse BBB, including clathrin-mediated and caveolae-mediated endocytosis. These factors contribute to the superior therapeutic efficacy of Ptzyme@D-ZIF in reducing behavioral disorders and pathological changes. Bioinformatics and biochemical analyses suggest that Ptzyme@D-ZIF inhibits neuroinflammation-induced apoptosis and ferroptosis in damaged neurons. The research uncovers the biodistribution, metabolic variances, and therapeutic outcomes of nanozymes-integrated chiral ZIF platforms, providing possibilities for devising anti-PD drugs.

Design and evaluation of multi-core raspberry-like platinum nanoparticles for enhanced photothermal treatment

While gold-based nanoparticles are now commonly used in nanomedicine due to their stability and high plasmonic resonance, platinum nanoparticles are recently emerging as promising candidates for enhancing radiotherapy sensitivity due to their high atomic number. Here, we demonstrate that platinum-based nanomaterials with a multi-core structure also possess efficient near-infrared photothermal properties, despite platinum’s maximum absorption being primarily in the ultraviolet region. The photothermal efficacy of these platinum multi-core raspberry-like nanoparticles is compared with single-core ultra-small platinum nanoseeds, within glioblastoma cancer spheroids, showcasing the potential of platinum nanocore aggregation for photothermal therapy in cancer treatment. Additionally, we used a microfabrication technique for high-throughput growth of spheroids in microwells to evaluate photothermal treatment on glioblastoma spheroids. Finally, X-ray absorption spectroscopy was conducted to analyze the stability and behavior of both nanoparticles in the cellular environment, indicating their excellent biostability. Moreover, even after laser application, none of the nanoparticles degraded but instead underwent reshaping into a more crystalline structure.

Confining Prepared Ultra-Small Nanozymes Loading Ato for Lung Cancer Catalytic Therapy/Immunotherapy.

Nanozymes with inherent enzyme-mimic catalytic properties combat malignant tumor progression via catalytic therapy, while the therapeutic efficacy still needs to be improved. In this work, we innovatively synthesized ultra-small platinum nanozymes (nPt) in confined domain of wormlike pore channel in gold nanobipyramidal-mesoporous silica dioxide nanocomposites, producing nanozyme carriers AP-mSi with photo-enhanced peroxidase ability. Afterwards, based on the prepared AP-mSi, the lung cancer nanozymes probe (AP-HAI) was ingeniously produced by removing SiO2 template, modifying HSA, and loading ATO as well as IR780. Under NIR light irradiation, inner AuP and IR780 collaborated for photothermal process, thus facilitating the peroxidase-like catalytic process of H2 O2 . Additionally, loaded atovaquone molecules (ATO), a cell respiration inhibitor, could impair tumor respiration metabolism and cause oxygen retention, hence enhancing IR780's PDT effectiveness. In a result, IR780's PDT property and nPt nanozymes' photo-enhanced peroxidase-like ability endowed probes a high ROS productivity, eliciting anti-tumor immune responses to destroy tumor tissue. Systematic studies revealed that the obvious ROS generation was obtained by the strategy of using nPt nanozymes and reducing oxygen consumption by ATO, which in turn enabled lung cancer synergetic catalytic therapy/ICD-based immunotherapy. The results of this work would provide theoretical justification for the practical use of photo-enhanced nanozyme probes. This article is protected by copyright. All rights reserved.

Ultrasmall platinum nanoclusters densely immobilized on hairy metal organic framework for nonenzymatic glucose detection

Rational design of non-enzymatic nanomaterials that possess the similar functions to natural enzymes holds great promise in chemical and biological molecule detection. In this work, a non-enzymatic electrochemical biosensor for detection of glucose was developed based on poly(2-vinylpyridine) (P2VP) grafted UiO-66 metal organic framework decorated with ultrafine platinum nanoclusters (PtNCs). The as-fabricated UiO-66-g-P2VP/PtNCs nanocomposite was then placed on an indium tin oxide (ITO) electrode to construct non-enzymatic glucose biosensor for electrochemical detection of glucose in alkaline electrolyte. The resulting UiO-66-g-P2VP/PtNCs/ITO modified electrode showed two linear responses over glucose concentration ranging of 0.01–5 mM and 5–18 mM with a low detection limit of 2.18 μM (S/N = 3). Moreover, the UiO-66-g-P2VP/PtNCs/ITO serving as an electrochemical biosensor was successfully applied to the rapid determination of glucose in human serum sample with a desirable result. Our findings pave the way for design and development of a promising artificial enzyme for the construction of high performance sensing platform.

Ultrasmall platinum nanoparticles synthesized in reline deep eutectic solvent explored towards the voltammetric sensing of riboflavin in beverages and biological fluids

We report a solvothermal synthesis of ultrasmall platinum nanoparticles (USPtNPs) with an average size of 0.204 ( ± 0.008) nm using reline deep eutectic solvent (DES) as a stabilizing medium at a temperature of 80 ºC. SEM and EDS were used to morphologically characterize the USPtNPs. These revealed approximately spherical shapes with emission lines characteristic of platinum. DES was characterized by FT-IR and NMR, which indicated its formation through hydrogen bonds between the precursors. DSC was also used to characterize the precursors and the formed DES. Furthermore, an electrochemical sensor for determining riboflavin (RB) in commercial energy drinks and biological fluids was developed using the USPtNPs together with multiwalled carbon nanotubes (MWCNT). The USPtNPs-DES/MWCNT/GCE film was characterized by SEM, which demonstrated the characteristic tubular morphology of MWCNT. The RB voltammetric response was studied, and a significant enhanced on the current response was observed, especially due to the USPtNPs. This sensor displayed a linear response for RB in the range of 0.02–1.2µmol L−1, with a limit of detection of 1.8 nmol L−1. Besides detectability at nanomolar range, excellent performance was verified for repeatability and anti-interference features. The sensor based on extraordinary USPtNPs synthesized in DES in a simpler and environmentally friendly way was successfully applied to determine RB in different matrices.

Ultrahigh Mass Activity Pt Entities Consisting of Pt Single atoms, Clusters, and Nanoparticles for Improved Hydrogen Evolution Reaction.

Platinum is one of the best-performing catalysts for the hydrogen evolution reaction (HER). However, high cost and scarcity severely hinder the large-scale application of Pt electrocatalysts. Constructing highly dispersed ultrasmall Platinum entities is thereby a very effective strategy to increase Pt utilization and mass activities, and reduce costs. Herein, highly dispersed Pt entities composed of a mixture of Pt single atoms, clusters, and nanoparticles are synthesized on mesoporous N-doped carbon nanospheres. The presence of Pt single atoms, clusters, and nanoparticles is demonstrated by combining among others aberration-corrected annular dark-field scanning transmission electron microscopy, X-ray absorption spectroscopy, and electrochemical CO stripping. The best catalyst exhibits excellent geometric and Pt HER mass activity, respectively ≈4 and 26 times higher than that of a commercial Pt/C reference and a Pt catalyst supported on nonporous N-doped carbon nanofibers with similar Pt loadings. Noteworthily, after optimization of the geometrical Pt electrode loading, the best catalyst exhibits ultrahigh Pt and catalyst mass activities (56 ± 3 A mg-1 Pt and 11.7 ± 0.6 A mg-1 Cat at -50mV vs. reversible hydrogen electrode), which are respectively ≈1.5 and 58 times higher than the highest Pt and catalyst mass activities for Pt single-atom and cluster-based catalysts reported so far.

Facile Synthesis and X-ray Attenuation Properties of Ultrasmall Platinum Nanoparticles Grafted with Three Types of Hydrophilic Polymers.

Ultrasmall platinum nanoparticles (Pt-NPs) grafted with three types of hydrophilic and biocompatible polymers, i.e., poly(acrylic acid), poly(acrylic acid-co-maleic acid), and poly(methyl vinyl ether-alt-maleic acid) were synthesized using a one-pot polyol method. Their physicochemical and X-ray attenuation properties were characterized. All polymer-coated Pt-NPs had an average particle diameter (davg) of 2.0 nm. Polymers grafted onto Pt-NP surfaces exhibited excellent colloidal stability (i.e., no precipitation after synthesis for >1.5 years) and low cellular toxicity. The X-ray attenuation power of the polymer-coated Pt-NPs in aqueous media was stronger than that of the commercial iodine contrast agent Ultravist at the same atomic concentration and considerably stronger at the same number density, confirming their potential as computed tomography contrast agents.

Lattice Mismatch-Induced Formation of Copper Nanoplates with Embedded Ultrasmall Platinum or Palladium Cores for Tunable Optical Properties.

Although noble metal nanocrystals have been studied extensively in the past decades, the shape-controlled synthesis of non-noble metal nanocrystals has remained challenging with limited success, which is a grand obstacle to their wide applications. Herein, a novel lattice mismatch-involved shape-control mechanism of Cu nanocrystals in a seed-mediated synthesis is reported, which can produce Cu nanoplates in high yield with tailored sizes (28-130nm), holding great potential in optical and catalytic applications. The lattice mismatch between Cu and the seed is found effective in inducing crystallographic defects for symmetry breaking toward anisotropic nanocrystals. While a too-large lattice mismatch (11.7% for Au seeds) leads to multiple twin defects to form quasi-spherical Cu nanocrystals, an appropriately large lattice mismatch (7.7% for Pt and 6.9% for Pd seeds) successfully induces planar defects for the formation of Cu nanoplates. The size of the Cu nanoplates is customizable by controlling the concentration of the seeds, leading to tunable optical properties. A prototype of a colorimetric indicator with Cu nanoplates, potentially applicable to the safety control of foods and drugs is demonstrated. This mechanism paves a new way for the shape-controlled synthesis of Cu and other metal nanocrystals for a broad range of applications.

Piezo‐Augmented and Photocatalytic Nanozyme Integrated Microneedles for Antibacterial and Anti‐Inflammatory Combination Therapy

AbstractWound infection is arguably the most common, and potentially the most devastating, complication of the wound healing process. The ideal treatment strategy has to eliminate bacteria, alleviate inflammation, and promote wound healing and skin formation. Herein, a multifunctional heterostructure is designed consisting of ultrasmall platinum–ruthenium nanoalloys and porous graphitic carbon nitride C3N5 nanosheets (denoted as PtRu/C3N5), which concurrently possesses piezoelectric enhanced oxidase ‐mimic nanozyme activity and photocatalytic hydrogen gas production capacity. Moreover, these hybrid nanotherapeutics are integrated in natural hyaluronic acid microneedles, which exhibit almost 100% broad‐spectrum antibacterial efficacy against multiple bacterial strains in vitro and in vivo within 10 min ultrasound treatment, and effectively inhibit inflammation reactions after 1 h visible light irradiation, promising for accelerating the cutaneous wound healing in the bacterial infected mice. This study highlights a competitive strategy for development of all‐in‐one antibacterial and anti‐inflammatory therapies.

Platinum nanoparticle-graphene quantum dot nanocage as a promising Schottky heterojunction electrocatalyst for electrochemical detection of vanillin in baby milk powder

Facile synthesis of platinum nanocrystal and its improvement in catalytic activity still face great challenges. The paper reports one strategy for synthesis of platinum nanoparticle-serine-functionalized and boron-doped graphene quantum dot composite (Pt-Ser-B-GQD). The Ser-B-GQD was prepared by pyrolysis of serine, boric acid and citric acid at 180 °C for 3 h and then reacted with chloroplatinic acid to form platiunm nanocrystal. The resultant Pt-Ser-B-GQD offers a nanocage-like structure composing of tiny graphene sheets connecting many ultrasmall platinum nanocrystals with an average particle size of 8.2 ± 0.32 nm. The combination of Pt nanocrystal with Ser-B-GQD results in the formation of Schottky heterojunction at the interface. The unique structure achieves to an improved catalytic activity. Pt-Ser-B-GQD was further used as Schottky heterojunction electrocatalyst for the construction of electrochemical sensor for the detection of vanillin. Because of excellent electrochemical properties, the sensor based on Pt-Ser-B-GQD exhibits a high sensitivity for electrochemical detection of vanillin. Differential pulse voltammetric peak current will increase linearly with increasing vanillin concentration in the range of 1 × 10−9-1 × 10−4 M with the detection limit of 2.8 × 10−10 Μ (S/N = 3). The proposed analytical method provides advantage of sensitivity, selectivity and reproducibility and was successfully applied in the detection of vanillin in baby milk powder.

Exosomes loaded with ultrasmall Pt nanoparticles: a novel low-toxicity alternative to cisplatin

BackgroundPlatinum nanoparticles have been demonstrated to have excellent anticancer properties. However, because of the lack of specificity they must be delivered to the tumor in amounts sufficient to reach the desired therapeutic objectives. Interestingly, exosomes are considered as excellent natural selective delivery nanotools, but until know their targeting properties have not being combined with the anticancer properties of platinum nanoparticles.ResultsIn this work we combine the targeting capabilities of exosomes and the antitumoral properties of ultrasmall (< 2 nm) platinum nanoparticles as a novel, low toxicity alternative to the use of cisplatin. A mild methodology based on the room temperature CO-assisted in situ reduction of Pt2+ precursor was employed to preserve the integrity of exosomes, while generating ultrasmall therapeutic PtNPs directly inside the vesicles. The resulting PtNPs-loaded exosomes constitute a novel hybrid bioartificial system that was readily internalized by the target cells inducing antiproliferative response, as shown by flow cytometry and microscopy experiments in vitro. In vivo Pt-Exos showed antitumoral properties similar to that of cisplatin but with a strongly reduced or in some cases no toxic effect, highlighting the advantages of this approach and its potential for translation to the clinic.ConclusionsIn this study, a nanoscale vector based on ultrasmall PtNPs and exosomes has been created exhibiting antitumoral properties comparable or higher to those of the FDA approved cisplatin. The preferential uptake of PtNPs mediated by exosomal transfer between certain cell types has been exploited to create a selective antitumoral novel bioartificial system. We have demonstrated their anticancer properties both in vitro and in vivo comparing the results obtained with the administration of equivalent amounts of cisplatin, and showing a spectacular reduction of toxicity.

Biodistribution and Toxicological Effects of Ultra-Small Pt Nanoparticles Deposited on Au Nanorods (Au@Pt NRs) in Mice with Intravenous Injection.

Pt-based nanostructures are one of the promising nanomaterials for being used in catalysts, sensors, and therapeutics. However, their impacts on the health and biological systems are not adequately understood yet. In this work, nanorods composed of ultrasmall platinum (Pt) nanoparticles deposited on the surface and gold nanorod as the core (Au@Pt NRs) were synthesized, and the distribution and toxic effects of Au@Pt NRs were investigated in C57BL/6 mice with intravenous injection by using atomic absorption spectroscopy (AAS), transmission electron microscope (TEM), hematoxylin-eosin (HE) staining and blood cell analyzer. At the time point of Day 1, Day 8 and Day 16 post injection of Au@Pt NRs (6 mg/kg of Pt atom), Au@Pt NRs were mainly accumulated in the liver and spleen. The energy dispersive spectrometer mapping images showed Au@Pt NRs experienced quick corrosion and Au released faster than Pt in the physiological environments. The catalase (CAT) activity in tissues increased slightly in the early stage of the Au@Pt NRs exposure and went down to the normal level. With HE staining, inflammatory cells infiltration could be seen in the tissues, while no significant influences were detected on the blood biochemistry and the function of liver and kidney. In conclusion, intravenously injected Au@Pt NRs mainly distributed in the liver and spleen with comparable levels, and did not exert any significant toxic effects on the organs' function within two weeks; meanwhile, Au@Pt NRs were able to degrade, which indicated acceptable safety to the mice and potentials of biomedical application.

Orally Administered Platinum Nanomarkers for Urinary Monitoring of Inflammatory Bowel Disease.

Inflammatory bowel disease (IBD) is a chronic relapsing autoimmune disease with rising incidence worldwide. There is an increasing desire for non-invasive diagnostic tools to enable simple and sensitive IBD monitoring. Here, we report an orally administered nanosensor which will dissociate into ultrasmall platinum nanoclusters (PtNCs) in IBD-related inflammatory microenvironments. By exploiting the enzyme-mimicking activity of PtNCs and the precise bandpass filterability of kidney, the released-PtNCs can be detected in a scalable urinary readout, such as fluorescence and volumetric bar-chart chip (V-Chip), for point-of-care (POC) analysis. Our results demonstrate that the nanosensors exhibit significant signal differences between IBD-model mice and healthy mice, which is more sensitive than clinical ELISA assay based on fecal calprotectin. Such a non-invasive diagnostic modality significantly assists in the personalized assessment of pharmacological and follow-up efficacy. We envision that this modular conception will promote the rapid diagnosis of diverse diseases by changing specific responsive components.

Mitochondria-targeted nanozymes eliminate oxidative damage in retinal neovascularization disease.

Retinal neovascularization is typically accompanied by hypoxia-induced oxidative injury in the vascular system. This study developed an ultrasmall (6-8nm) platinum (Pt) nanozyme loaded mitochondria-targeted liposome (Pt@MitoLipo) to alleviate hypoxia and eliminate excess reactive oxygen species (ROS) for effective retinal neovascularization disease therapy. Pt nanozymes possess superoxide dismutase (SOD) and catalase (CAT) cascade enzyme-like activities, which convert cytotoxic O2•- and H2O2 into nontoxic H2O and O2. Triphenylphosphonium (TPP)-conjugated liposomes were coated on the surface of Pt nanozymes to increase their biocompatibility and help them penetrate the cell membrane, escape from the lysosomal barrier, and target mitochondria, thus achieving precise scavenging of mitochondrial O2•- and relief from hypoxia. Using an oxygen-induced retinopathy (OIR) mouse model, we demonstrated that Pt@MitoLipo nanozymes significantly suppressed hypoxia-induced abnormal neovascularization and facilitated avascular normalization of the retina in vivo without any noticeable toxicity. This study provides a promising way to break through cellular barriers and target scavenging mitochondrial O2•- and illustrates the potential of ROS-scavenging and hypoxia relief in retinal neovascularization disease therapy.

Impact of platinum loading and dispersion on the catalytic activity of Pt/SnO2 and Pt/α-Fe2O3

The Pt/SnO2 (SP-samples) and Pt/α-Fe2O3 (FP-samples) with platinum loadings between 1 and 10 mol% were synthesized mechanochemically starting from platinum(II) acetylacetonate dissolved in toluene and from SnO2 and α-Fe2O3 powders obtained from tin(II) and iron(II) acetates. The STEM results show that the ultrasmall platinum nanoparticles (PtNPs) are well dispersed on the SnO2 and α-Fe2O3 supports. The PtNPs size distributions calculated with lognormal functions ranged from 1.0 to 1.3 nm. The results of temperature programmed reduction in hydrogen showed maxima at 120–160 °C due to the reduction of PtOx to Pt0. The Pt-4f-XPS results showed that the dispersed platinum on the SnO2 and α-Fe2O3 supports consisted of all three oxidation states of platinum: Pt4+, Pt2+ and Pt0. The average oxidation state of platinum as a function of molar fraction of Pt loading in the SP samples varies from 1.69 to 2.11, whereas the oxidation state of Pt in the FP samples varies more linearly and steeply from 1.42 to 2.58. The synthesized samples showed high catalytic activity for the reduction of 4-nitropenol (4-NP) to 4-aminophenol (4-AP), which can be explained by the high dispersion of non-aggregated ultrasmall PtNPs with a size of about 1 nm on the SnOx and FeOx supports.