Polydopamine nanomedicine-enabled antioxidation against senescence

doi:10.21203/rs.3.rs-1538316/v1

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Polydopamine nanomedicine-enabled antioxidation against senescence

https://doi.org/10.21203/rs.3.rs-1538316/v1

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Senescence is a cellular response characterized by cells irreversibly stopping dividing and entering a state of permanent growth arrest. One of the underlying causes of senescence is the oxidative stress-induced damage, indicating that eliminating the reactive oxygen and nitrogen species (RONS) may be beneficial to prevent and/or alleviate senescence. Herein, we develop biocompatible ultra-small polydopamine nanoparticles (UPDA NPs) featuring broad-spectrum RONS-scavenging capacities. The UPDA NPs can restore senescence-related renal function, tissue homeostasis, fur density and motor ability in mice, potentially associated with the regulation of multiple genes involved in lipid metabolism, mitochondrial function, energy homeostasis, telomerase activity, neuroprotection, and inflammatory responses. We also demonstrate that the dietary UPDA NPs can reduce the RONS level, enhance the climbing ability and prolong the lifespan of Drosophila. Our findings reveal that the developed UPDA NPs can delay aging through RONS elimination and provide a paradigm and practical strategy for clinically treating senescence and senescence-related diseases.

Senescence or biological aging is a state of irreversible cell growth arrest accompanied with the halt of cell division before cells reach the end of their lifespan ¹. Senescence can lead to systemic changes, which are associated with various chronic diseases such as Alzheimer's disease², diabetes³, atherosclerosis⁴ and cancer⁵, posing a heavy burden on society. In addition to natural aging, senescence occurs in response to various noxious stimuli, including DNA damage, oncogenic stress, telomere dysfunction, inflammation, mitochondrial dysfunction, epigenetic alterations, proteostasis imbalance, dysregulated intracellular signaling pathways and oxidative stress (reviewed in ^6,7). As one of the fundamental mechanisms driving aging, oxidative stress has received continued and even increasing attention, as a phenomenon characterized by the imbalance between reactive oxygen and nitrogen species (RONS)-related oxidants and antioxidants⁸. The free radical theory of aging posits that age-associated functional losses result from the accumulation of oxidative damage caused by RONS. RONS are reactive radical and non-radical derivatives of oxygen and nitrogen, such as superoxide anion radical (•O₂⁻), hydrogen peroxide (H₂O₂), hydroxyl radical (•OH), nitric oxide radical (•NO), and nitrite peroxide (OONO⁻), continuously produced in the process of cell metabolism or upon the stimulation of environmental factors⁹. RONS, whether endogenous or exogenous, induce the oxidative modification of most biological macromolecules including proteins, lipids, carbohydrates and nucleic acids, and further change their stability and function⁸. Therefore, there is an urgent need to develop an effective strategy to eliminate or reduce excessive RONS ultimately delaying the aging process.

Living organisms possess a series of highly effective enzymes including catalase (CAT)¹⁰ and superoxide dismutase (SOD)¹¹ with the ability to remove RONS, protecting tissues or organs from oxidative damage. However, these enzymes are sensitive to adverse environmental conditions (e.g., extreme temperatures)¹² making them difficult to produce in large quantities. To date, a number of artificial enzymes with RONS-scavenging capacities have been developed for the treatment of various diseases including acute kidney injury¹³, hepatic ischemia-reperfusion injury¹⁴ and neurodegenerative diseases¹⁵, mimicking the activities of natural enzymes, which have the advantages of easy generation, low cost, multifunction and high stability. Among them, common inorganic nanozymes with antioxidant properties, such as CeO₂, Pt, V₂O₅ and 2D carbides and nitrides (MXenes)^{16, 17}, have been reported. However, further clinical translation of nanozymes has been restricted due to non-negligible toxicity issues in biological systems (cells, tissues, organs, etc.)¹⁸.

Compared to inorganic nanozymes, organic polymer-based nanozymes exhibit satisfactory biocompatibility and chemical flexibility¹⁹. Among them, polydopamine (PDA) which is widely used for synthesizing artificial melanin (eumelanin) has significant advantages in terms of biosafety²⁰. In previous reports, PDA is mainly utilized as a theranostic agent in the biomedical field due to its feasible surface modification, which can respond to various external stimuli such as light, pH and ultrasonic/magnetic field²¹. This inherent flexibility of PDA motivated us to explore its response to oxidative stress under pathological conditions and its potential effects on senescence. In the present study, we designed and developed ultra-small polydopamine nanoparticles (UPDA NPs) via liquid-phase exfoliation technology, integrated with CAT/SOD mimetic cascade activities and broad-spectrum reactive oxygen species (ROS)-scavenging capabilities, which can catalyze •O₂⁻ to generate H₂O₂ and O₂, decompose H₂O₂ into H₂O and O₂, and remove •OH. Additionally, UPDA NPs can serve as a scavenger for reactive nitrogen species (RNS) such as •NO and OONO-. We verify that UPDA NPs possess excellent biocompatibility and biosafety in vivo and the anti-senescence effects of UPDA NPs are likely related to but not limited to the regulation of the NF-κB signaling pathway. Further evaluation demonstrates that UPDA NPs can attenuate oxidative stress-induced senescence both in vitro and in vivo. Particularly, UPDA NPs can rescue drug-induced senescent behaviors in mice and can effectively restore the lifespan of Drosophila under oxidative stress (Fig. 1). These results not only demonstrate that UPDA NPs can be used as a paradigm of anti-aging nanomedicine that feature desirable RONS-scavenging performance with potential clinical application prospect, but also provide an alternative and efficient strategy for the alleviation and treatment of senescence.

Synthesis and characterization of UPDA NPs. The PDA particles were initially synthesized via oxidative self-polymerization of dopamine in alkaline solution (Fig. 2a), which show very weak colloidal stability with the particle size ranging from the scale of nanometer to that of micrometer (Fig. 2b, c). The UPDA NPs can be facilely acquired from PDA particles via ultrasonication-mediated liquid-phase exfoliation technique. Compared with PDA particles (Fig. 2b PDA), after exfoliation, the UPDA NPs display benign dispersity and stability (Fig. 2b UPDA). Transmission electron microscopy (TEM) images reveal the uniform sizes and morphology of UPDA NPs (Fig. 2d, e). The atomic force microscopy (AFM) image further demonstrates the successful synthesis of UPDA NPs with high quality and an average size of around 3 nm (Supplementary Fig. 1a), which is consistent with what is observed in TEM images. The dynamic light scattering (DLS) analysis shows that the hydrodynamic diameter of UPDA NPs is 2.4, 5.6, 2.7, 4.9 and 5.2 nm in water, phosphate buffer saline (PBS), bull serum albumin (BSA), foetal bovine serum (FBS) and dulbecco’s modified eagle medium (DMEM), respectively, and no obvious precipitation is observed after 72 h (Supplementary Fig. 1b), which indicates that the obtained UPDA NPs are relatively stable in various physiological environments and the size falls in the range of the glomerular filtration size threshold of 6 ~ 8 nm²² (Fig. 2f). Furthermore, the functional groups of UPDA NPs are examined by utilizing Fourier transform infrared (FT-IR) spectrometer (Fig. 2g) with different adsorption bands indicating the presence of O-H, N-H and C-OH, in which the adsorption band at ~ 3432 cm^− 1 is assigned to the stretching vibration of O-H and N-H, the peak located at ~ 1677 cm^− 1 is indexed to the stretching vibration of aromatic ring and bending ring vibration of N-H, the peaks at ~ 1377 cm^− 1 and 1498 cm^− 1 are ascribed to the stretching and bending vibration of C-OH, and the peak at ~ 1590 cm^− 1 is assigned to the stretching vibration of the amide group, suggesting that UPDA NPs have been successfully synthesized²³. Ultraviolet visible (UV-Vis) absorption spectra acquired on UPDA NPs display a broad and intense absorption band from the ultraviolet region to the visible light region and the absorption is enhanced with the increased concentration of UPDA NPs, demonstrating excellent dispersity (Supplementary Fig. 1c). The X-ray powder diffraction (XRD) pattern indicates the amorphous nature of UPDA NPs with intermolecular stacking structure (Supplementary Fig. 1d). Based on the X-ray photoelectron spectroscopy (XPS) analysis, the C, N, and O elements are present in the acquired UPDA NPs (Fig. 2h, Supplementary Fig. 2), further confirming the successful synthesis of UPDA NPs without residual by-products.

RONS-scavenging capability and SOD/CAT-like activity of UPDA NPs. The classic 2,2′-azino-bis (3-ethylbenzothiazoline 6-sulfonate) (ABTS) radical assay was performed to assess the total antioxidant capacity (TAC) of UPDA NPs, in which ABTS radical cation (ABTS•⁺) is decolorized by antioxidants. The results indicate that UPDA NPs feature high antioxidant activity in a concentration-dependent manner (Fig. 3a), and more than 80% of total ROS can be eliminated by 40 µg mL^− 1 UPDA NPs (Supplementary Fig. 3a). Significantly, the TAC of UPDA NPs is twice as much as that of 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox), a water-soluble analog of vitamin E (Supplementary Fig. 3b).

•O₂⁻, as the initial ROS, not only attacks unsaturated fatty acids causing lipid peroxidation, but also generates other oxygen free radicals through a series of reactions damaging organisms. SOD can catalyze •O₂⁻ into H₂O₂ and O₂, and thus SOD mimics can be used as a potential therapeutic agent against oxidative stress¹¹. The SOD-like activity of UPDA NPs was assessed via the typical 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium) (WST-1) method. WST-1 reacts with •O₂⁻ with the catalysis of xanthine oxidase (XOD), generating formazan, the absorbance of which can be measured at 450 nm and is negatively correlated with the SOD activity. UPDA NPs efficiently inhibit the formazan generation with an IC₅₀ value of 39.98 µg mL^− 1, suggesting a high SOD-like activity (Fig. 3b).

H₂O₂ is another kind of ROS that can induce numerous cellular events including cellular senescence. In living organisms, CAT collaborates with SOD to catalyze the decomposition of H₂O₂ into H₂O and O₂ for maintaining the redox homeostasis²⁴. The CAT-like activity of UPDA NPs can be evaluated by detecting the absorbance change of H₂O₂ at 240 nm, which is an inherent characteristic of H₂O₂. In the presence of UPDA NPs, the absorbance value of H₂O₂ decreases significantly with time, indicating UPDA NPs can effectively consume H₂O₂ (Supplementary Fig. 4a). Additionally, the electron spin resonance (ESR) spin label oximetry was conducted to assess the CAT-like activity of UPDA NPs by monitoring the O₂ generation employing an oxygen-sensitive probe 3-carbamoyl-2,2,5,5-tetramethyl-3-pyrrolin-1-yloxy (CTPO). This assay shows a time-dependent decrease in the peak intensities of ESR signals (Fig. 3c), indicating continuous O₂ production. Furthermore, the spectrophotometric method was used to further assess the CAT-like function of UPDA NPs (Fig. 3d). In an acidic environment, H₂O₂ can oxidize Fe²⁺ to Fe³⁺, and Fe³⁺ combines with xylenol orange (XO) to form Fe³⁺ dye complexes. The complexes have a maximum absorption wavelength at 640 nm and the absorption value is proportional to the concentration of H₂O₂²⁵. The results demonstrate that 84% of H₂O₂ is eliminated by using 50 µg mL^− 1 UPDA NPs (Supplementary Fig. 4b). In order to clarify the catalytic mechanism of the CAT-like activity, a steady-state kinetic assay was conducted by adding H₂O₂ with different concentrations (5 to 60 µM) to UPDA NPs with a fixed concentration (Fig. 3e), which follows the representative Michaelis-Menten kinetics (Fig. 3f). By fitting a Lineweaver-Burk plot, the Michaelis-Menten constant (K_m) and maximum velocity (V_max) values are calculated to be 87.0 µM and 1.5 µM·s ^− 1, respectively (Fig. 3g).

•OH is one of the most reactive free radicals, which features stronger chemical reactivity and can dramatically aggravate oxidative damage²⁶. Methylene blue (MB) was utilized as the chromogenic substance to demonstrate the •OH-scavenging effect of UPDA NPs, in which the blue-colored MB with a maximum absorbance at 664 nm turns colorless in the presence of •OH²⁷. The data show that UPDA NPs can effectively prevent the color fading of MB (Fig. 3h) and 75% of •OH is eliminated by using 90 µg mL^− 1 UPDA NPs (Supplementary Fig. 5). Moreover, 50 µg mL^− 1 UPDA NPs reduce the ESR signal of the •OH spin-trapped adduct of 5,5-dimethyl-1-pyrroline N-oxide (DMPO) to nearly the background level, indicating robust •OH-scavenging activity of UPDA NPs (Fig. 3i).

Besides ROS, RNS, whether endogenous or exogenous, can induce cellular oxidative damage and further cause senescence²⁸. The total RNS-scavenging activity of UPDA NPs was examined based on the elimination test of 1,1-diphenyl-2-picrylhydrazyl free radical (DPPH•), which is a stable N free radical and colorimetric probe with a large number of unpaired electrons²⁴, showing a strong absorption at 532 nm. The nitrogen lone pair electrons can be combined and the corresponding absorption can be weakened in the presence of RNS scavenger. Our results reveal that UPDA NPs can effectively eliminate DPPH• in a concentration-dependent manner (Fig. 3j). Approximately 85% of DPPH• is decomposed by 100 µg mL^− 1 UPDA NPs (Supplementary Fig. 6). Among RNS, excessive •NO can cause cytotoxicity and accelerate aging²⁹. The •NO-scavenging activity of UPDA NPs was assessed by using 2-(4-Carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3oxude (carboxy-PTIO) as the •NO indicator, and 3,3-bis(aminoethyl)-1-hydroxy-2-oxo-1-triazene and 2,2'-(hydroxynitrosohydrazino) bis-ethanamine (NOC 18) as the •NO donner³⁰. In the absence of UPDA NPs, carboxy- reacts with •NO to generate carboxy-PTI, resulting in an increase of the ESR signal from 5 to 7 peaks. Comparatively, when UPDA NPs are added, the ESR signal is restored to 5 peaks (Fig. 3k). •O₂⁻ can react with •NO resulting in the formation of peroxynitrite anion (OONO⁻), which is a highly oxidative and cytotoxic factor. Pyrogallol red with an absorbance peak at 545 nm has been commonly used as an indicator for OONO^− 30, which is substantially inhibited by UPDA NPs and 88% of OONO⁻ is scavenged by 100 µg mL^− 1 UPDA NPs (Fig. 3l and Supplementary Fig. 7), Taken together, all these results demonstrate that UPDA NPs possess outstanding RONS-scavenging abilities.

In terms of chemical structures and functionalities, PDA is very similar to eumelanin, the most common form of melanin³¹. In eumelanin, for scavenging RONS, intermolecular connections between 5,6-dihydroxyindole-2-carboxylic acid (DHICA) oligomers can distort the dihedral angles between rings to minimize electrostatic interactions. The stacking difficulties of oligomers cause the delocalization of π electrons, and the weak intermolecular aggregation makes them easier for radicals to access DHICA melanin and exhibit stronger antioxidant capacity³². Similarly, as a eumelanin-like agent, the free radical-scavenging property of UPDA NPs is significantly affected by the degree of electron delocalization in the plane of the oligomer in its microstructure (Fig. 3m), which is related to the reactivity of polycatechol structure on the surface and the intrinsic lifetime of the inner radicals³³. In addition, the ultrafast energy transfer facilitated by ion binding is another way for melanin to quench chemically active molecules³⁴. The typical redox chemistry of catechins endows UPDA NPs with the function of scavenging various free radicals (Fig. 3n). On the one hand, the catechol provides hydrogen atoms from phenolic hydroxyl groups to quench RONS free radicals. On the other hand, catechol can also reduce RONS via electron transfer, and the resulting phenoxy radicals further form a stable quinone structure by interacting with the second radical³⁵ (Fig. 3o).

UPDA NPs are biocompatible and regulate the expression of key genes involved in multiple biological functions. To explore the therapeutic effects of UPDA NPs, we firstly evaluated their biocompatibility and biosafety in mice. There is almost no necrosis, congestion or bleeding in the main organ tissues including the heart, the liver, the spleen, the lung and the kidney after intravenous injection of UPDA NPs at a dose of 2 mg/kg, revealing no adverse effects (Supplementary Fig. 8a). The crucial hematological parameters, including white blood cells (WBC), lymphocytes (LYM), monocytes (MON), granulocytes (GRA), mean platelet volume (MPV), red blood cells (RBC), hemoglobin (HGB), mean corpuscular hemoglobin (MCH), hematocrit (HCT), red blood cell distribution width-standard deviation (RDWSD), mean corpuscular volume (MCV), mean corpuscular-hemoglobin concentration (MCHC), platelet (PLT), platelet distribution width (PDW) and red blood cell distribution width-coefficient of variation (RDWCV) have no significant differences between the control group and UPDA NPs-treated group (Supplementary Fig. 8b-p), indicating that UPDA NPs possess benign biocompatibility and high biosafety. Moreover, the inherent brownish yellow color of UPDA NPs makes them directly visible in the bladder (Supplementary Fig. 9), which confirms that UPDA NPs are eventually cleared from the kidney through urine excretion.

To elucidate the underlying mechanisms of UPDA NPs against oxidative stress, we performed transcriptomics analysis on the kidney of a senescent mouse model treated with an anthracycline class chemotherapeutic drug doxorubicin (DOX), which can induce cancer cell senescence³⁶ (Fig. 4a). An unsupervised principal component analysis (PCA) reveals that there is a significant difference in the transcriptomic profile of the kidney between the untreated group and UPDA NPs-treated group (Fig. 4a). As shown in the volcano plot, 960 differentially expressed genes (DEGs) (Fig. 4b) were identified, including 474 upregulated DEGs and 486 downregulated DEGs. It is noticed that the networks of DEGs are enriched in multiple signaling pathways shown by Kyoto Encyclopedia of Genes and Genomes (KEGGs) analysis (Fig. 4c), and that the functions of these DEGs are mostly related to aging and oxidative stress shown by Gene Ontology (GO) analysis (Fig. 4d). Further, we collected DEGs enriched in the pools related to aging and oxidative stress (Fig. 4e). Among the upregulated DEGs, we found genes important in lipid metabolism (Apod, apolipoprotein D), mitochondrial functions (Ucp1 and Ucp3, uncoupling proteins), telomerase activity (Tert, telomerase reverse transcriptase), energy balance (lep, letpin) as well as neuronal proliferation and survival (Bdnf, brain-derived neurotrophic factor); whereas, in the pool of downregulated DEGs, genes involved in the regulation of inflammatory responses such as Arger (advanced glycosylation end product-specific receptor) and Ccn2 (cellular communication network factor 2) were identified (Fig. 4f). This indicate that the antioxidant activity of UPDA NPs combines multiple mechanisms against senescence. Additionally, we took advantage of the Search Tool for the Retrieval of Interacting Genes (STRING) to obtain the protein-protein interaction (PPI) network for the DEGs related to aging and oxidative stress. Several hub genes were identified, including proinflammatory cytokines interleukin-1β (IL-1β) and interleukin-6 (IL-6), and cell cycle regulators p16^ink4a, p21 and p53 (Fig. 4g).

UPDA NPs suppress oxidative stress-induced senescence in vitro and in vivo. To further verify the hub genes related to the anti-aging effects of UPDA NPs, we firstly investigated whether UPDA NPs are effective in attenuating oxidative stress-induced senescence in human embryonic renal epithelial 293T cells treated with DOX. Our results show that UPDA NPs do not induce obvious cytotoxicity and the cell survival rate is above 80% even at a high concentration of 200 µg mL^− 1 (Supplementary Fig. 10). D-galactose (D-gal) has been generally applied as an inducer to accelerate aging as shown before³⁷. Similar to H₂O₂, an increase in ROS level shown by 2’, 7’-Dichlorofluorescin diacetate (DCF) is exhibited in cell groups after DOX or D-gal incubation (Fig. 5a, b). Distinctly, UPDA NPs effectively decrease the ROS generation caused by H₂O₂, DOX or D-gal, and thus protect 293T cells from ROS-induced cytotoxicity (Fig. 5a, b). Quantitative analysis of intracellular ROS levels via flow cytometry further confirms that UPDA NPs even at a low dosage of 20 µg mL^− 1 possess the desirable capability to protect the cells against DOX-induced oxidative stress (Fig. 5c).

Senescence is commonly accompanied by an increase in the activity of senescence-associated β-galactosidase (SA-β-GAL)³⁸. As expected, we found that SA-β-GAL expression is elevated with the increased concentration of DOX and the cell number begins to decrease when the concentration of DOX exceeds 0.2 × 10^− 6 M (Supplementary Fig. 11). It has been reported that senescence-related cell cycle arrest is activated by p16^INK4A/pRB and/or p53/p21^WAF1/CIP1 tumor suppressor pathways⁷. We found a notable increase of p16^ink4a expression after DOX stimulation, whereas UPDA NPs effectively diminish this effect (Fig. 5d, g). Western blotting (WB) results reveal that p21 and another senescence mediator, decoy receptor 2 (DcR2)³⁹, are overexpressed in DOX-treated 293T. Strikingly, after UPDA NPs treatment, the protein levels of both p21 and DcR2 decrease (Fig. 5j, k). Alongside the aforementioned senescence markers, the expression of Forkhead box O4 protein (FOXO4), a transcription factor and an interactor of p53, is boosted by DOX and diminished by UPDA NPs (Fig. 5d, e). Furthermore, the levels of senescence-associated secretory phenotypes (SASPs) cytokines IL-1β and IL-6 were quantified using enzyme-linked immunosorbent assay (ELISA) kits, which demonstrates that UPDA NPs can significantly downregulate their expression in senescent 293T cells (Fig. 5h, i). Interestingly, the expression level of nuclear lamin protein lamin B1, the loss of which is seen as a senescence marker⁴⁰, is restored following UPDA NPs treatment in DOX-induced senescent cells (Fig. 5d, f, j, k).

Next, the anti-senescence potentials of UPDA NPs were assessed in mice treated with DOX. The expression of both p21 and p53 is upregulated after DOX treatment, while their levels are significantly decreased after UPDA NPs treatment (Fig. 6a, b, d). Moreover, consistent with our results in vitro, lamin B1 expression is attenuated by DOX, which is obviously restored after UPDA NPs treatment (Fig. 6a, c). Collectively, these results demonstrate that UPDA NPs have great potential for reversing oxidative stress-induced aging, perhaps via the regulation of SASPs-related molecules.

UPDA NPs display anti-aging effects in vivo. Based on the promising prospects of UPDA NPs in the treatment of senescence, we evaluated the physiological and physical functions of DOX-treated mice (Fig. 7a). Compared with the control group, the levels of classical indicators of renal and hepatic functions including creatinine (CRE), blood urea nitrogen (BUN), alanine aminotransferase (ALT), and aspartate aminotransferase (AST) are elevated in DOX-exposed mouse group (Fig. 7b-e), indicating that DOX triggers liver and kidney damage. In contrast, after UPDA NPs treatment, these parameters return to their normal levels, demonstrating the protective effects of UPDA NPs for liver and kidney. To further assess the treatment efficacy of UPDA NPs, the swimming behaviors of mice were tracked and evaluated (Fig. 7f). Our results show that the average swimming speed of DOX-treated senescent mice is measured to be 123.36 mm s^− 1. Interestingly, after UPDA NPs treatment, the DOX-treated mice exhibit an enhanced swimming ability with a higher average swimming speed (212.86 mm s^− 1). Furthermore, the body weight of DOX-treated mice displays an apparent decrease, which is significantly ameliorated by UPDA NPs (Fig. 7g). In the aging phenotype evaluation, age-related hair loss is clearly observed in DOX-treated mice, whereas there is a significant increase in the hair density of DOX-treated mice following UPDA NPs treatment (Fig. 7h), further demonstrating the effective anti-senescence effects of UPDA NPs.

Dietary UPDA NPs delay aging in Drosophila. Due to the low culture cost, high reproductive rate, and short generation time and lifespan, Drosophila has been used as a model organism in senescence research for a long time⁴¹. We examined the effects of dietary UPDA NPs on the senescence and lifespan in Drosophila (Fig. 8a). As expected, the ROS level in Drosophila shown by redox-sensitive fluorescent probe dihydroethidium (DHE), is raised by D-gal, while dietary UPDA NPs can significantly reduce D-gal-induced increase of ROS level (Fig. 8b). The climbing ability of D-gal-fed Drosophila is significantly improved after UPDA NPs treatment. Specifically, the average climbing speed of D-gal treated Drosophila is about 0.37 cm s^− 1, which is increased to 0.58 cm s^− 1 by dietary UPDA NPs (Fig. 8c). Additionally, while D-gal forcefully shortens the maximum longevity of Drosophila to 37 days, UPDA NPs feeding can prolong the maximum life span of D-gal-treated Drosophila to 46 days, identical to that of the control group (Fig. 8d). The immunostaining of caspase 3 was performed to visualize the apoptosis in the brain of Drosophila (Fig. 8e), demonstrating that UPDA NPs obviously inhibit D-gal-caused cell apoptosis. Taken together, our results indicate that UPDA NPs may play an important role in protecting Drosophila from D-gal triggered aging.

Senescence is known to play an important role in several debilitating diseases including neurodegenerative diseases, metabolic disorders and cancers. In the present study, we focused on eliminating one of the key contributors for senescence, the RONS, by means of biocompatible nanomedicine. Since dopamine is a natural antioxidant and its polymer polydopamine is a widely used biomaterial in the medical field, we developed UPDA NPs to further explore their therapeutic potentials for senescence.

UPDA NPs not only exhibit CAT/SOD mimetic activities with a wide range of ROS-scavenging capabilities but are also effective in removing RNS such as •NO and OONO-. We speculate that the radical-scavenging properties of UPDA NPs are attributed to the catechol groups in their chemical structure, which can capture RONS free radicals through a dual effect of hydrogen atom transfer and electron transfer.

Our UPDA NPs are proven to be safe and biocompatible in vivo. In-depth transcriptomics analysis reveal that UPDA NPs can enhance the expression of anti-aging genes on the molecular level. ApoD, a lipocalin mainly expressed in the nervous system, is believed to restrain lipid peroxidation and act against oxidative stress in the brain⁴². Ucp1, a biomarker of the brown adipose tissue, has reduced expression and activity during aging⁴³. While Ucp1 deficiency leads to the overproduction of mitochondrial superoxide and vascular inflammation, Ucp1 knockin in pigs prevents NLRP3 inflammasome activation and protects the animals against coronary atherosclerosis⁴⁴. Another UPDA-NPs-upregulated uncoupling protein Ucp3 is a negative regulator of mitochondrial ROS generation and has protective effects against oxidative stress in skeletal muscle and heart⁴⁵. Tert, the catalytic subunit of telomerase, a generally recognized inhibitor of cellular senescence⁴⁶, is altered by UPDA NPs. Acute administration of leptin, a key player in the maintenance of energy homeostasis, can reduce oxidative stress levels by suppressing superoxide generation and promote cell proliferation in the brain of an Alzheimer’s disease mouse model⁴⁷. In the presence of UPDA NPs, leptin expression changes. Bdnf, a neurotrophin essential for neuronal survival and synaptic transmission, has been shown to maintain redox balance in neuronal cultures⁴⁸ and reverse microglial activation in aged mice via the inhibition of NF-κB activity⁴⁹.

Interestingly, UPDA NPs are capable of regulating multiple signaling pathways, including the NF-κB signaling pathway, a fundamental stimulator of SASPs⁵⁰. Among the downregulated DEGs, Arger, also known as receptor for advanced glycation end products (RAGE), can activate NF-κB signaling pathway, which in turn leads to inflammation⁵¹. Another downregulated gene Ccn2 is found to enhance NF-κB signaling by binding to a receptor activator of NF-κB (RANK)⁵². Additionally, NF-κB signaling pathway can be activated by an array of stimuli, including proinflammatory cytokines IL-6 and IL-1β⁵³. The production of both IL-6 and IL-1β is attenuated by UPDA NPs in senescent cells. Therefore, our results imply that the anti-senescence potentials of UPDA NPs may be related to the suppression of NF-κB signaling pathway and play a part in inflammatory regulation.

It is of note that DEGs regulated by UPDA NPs are involved in a variety of cellular physiological activities covering lipid metabolism, mitochondrial function, energy balance, telomere stability, neuroprotection and immune response. Our in vitro and in vivo studies support multiple anti-aging mechanisms of UPDA NPs, as these particles are also capable of regulating the expression of the hub genes in the protein-protein interactome of DEGs. Cell cycle arrest marker p16^INK4A is a key player in oncogene-induced senescence and has been shown to promote tissue aging and inflammation^{54, 55}. The upregulation of cyclin-dependent kinase inhibitor p21 and its transcription activator p53 are thought to be involved in senescence-related diseases⁵⁶.Our results suggest that UPDA NPs are able to inhibit the expression of p16^INK4A, p53 and p21, which is in line with a study showing the anti-aging mechanism of gold nanoparticles⁵⁷. Moreover, the interaction between FOXO4 and p53 is considered as a potential target for developing treatment strategies for age-related illnesses⁵⁸, which is supported by our observation that anti-senescence UPDA NPs can downregulate the expression of FOXO4 and p53. Particularly, in both senescent cells and mouse kidney, UPDA NPs are able to recover the loss of lamin B1, a protein crucial to maintain the structural integrity of the nucleus, which is impaired at the beginning of senescence⁵⁹. Another senescence marker DcR2 suppressed by UPDA NPs, has been shown to be related to the premature senescence involved in kidney fibrosis³⁹. Thus, our results suggest that UPDA NPs may participate in preventing the onset of aging. Importantly, the therapeutic potentials of UPDA NPs in the treatment of senescence are confirmed by the improvements of senescent phenotypes and behavioral performances of aging mice. What is even more remarkable is that UPDA NPs can restore the lifespan of Drosophila, which is likely to be associated with the prevention of apoptosis in the brain. Thus, the anti-senescence effects of UPDA NPs may derive from a combination of different mechanisms against aging and are worthy of further investigation.

In conclusion, we have engineered a uniform and stable organic polymer-based nanozyme UPDA NPs that features extensive RONS-eliminating capacities and anti-senescence potentials. The antioxidant properties of UPDA NPs are reflected by their cytoprotective and anti-aging effects in cultured cells and model organisms. We propose that UPDA NPs-enabled antioxidation against senescence involves multiple molecular mechanisms and may provide further insights into the application of organic nanomedicine in the treatment of premature senescence and senescence-related diseases.

Chemical materials. Dopamine hydrochloride, sodium hydroxide (NaOH), sodium nitrite (NaNO₂), doxorubicin hydrochloride (DOX), 1,1-Diphenyl-2-picrylhydrazyl radical (DPPH), DETA NONOate (NOC18), 5,5-dimethyl-1-pyrrolineN-oxide (DMPO), 4,5-Dihydro-4,4,5,5-tetramethyl-2-phenyl-1H-imidazol-1-yloxy-1-oxide (PTIO), X-Gal (5-bromo-4-chloro-3-indolyl-β-D-galactoside) and dihydroethidium (DHE) were purchased from Meryer (Shanghai) Chemical Technology. Phosphate-buffered saline (PBS, pH 7.4, Na₂HPO4-NaH₂PO₄, 10 mM) solution was prepared in the laboratory. All chemicals and reagents were of analytical grade and used as received without further purification. Ultrapure water (18.2 MΩ cm^− 1 at 25°C) purified by a Milli-Q system was used throughout the experiment.

TEM imaging and spectroscopic analysis. TEM imaging was conducted on a JEM-1400Flash HC (JEOL, Japan) at 120 kV. The sample was prepared by dispersing a small amount of freeze-dried powder in PBS. Then, the suspension was dropped on 230 mesh copper TEM grids covered with thin amorphous carbon films. FT-IR spectra were measured by a VERTEX70 spectrometer (Bruker, Germany) in the range of 4000–400 cm^− 1. UV-vis spectra were obtained using a VNANODROP 8000 spectrometer (Thermo, Germany). A DLS particle size analyzer (Malvern 2000, U.S.A) was used to determine the hydrophilic diameters of the particles. XPS was performed with an ESCALAB 250Xi (thermofisher scientific, China) X-ray source. The crystal structure and oxidation state of UPDA NPs were analyzed using a X-ray diffractometer (XRD, Smartlab, China). The ESR spectroscopy signal was obtained on a Bruker A300 (X-band) spectrometer (Bruker, Germany). All the measurements were performed at room temperature if not specified otherwise.

Preparation of UPDA NPs. 180 mg of dopamine hydrochloride was dissolved in 90 mL of deionized water. 840 µL of 1 mol L^− 1 (M) NaOH solution was added to the dopamine hydrochloride solution at 60°C and the mixture underwent vigorous stir. The reaction lasted for 5 h. The solution color turned to pale yellow as soon as NaOH was added and gradually changed to dark brown. The product was collected by centrifugation at 16000 rpm for 20 min and was then washed with deionized water three times. The aqueous solvent was removed by freeze-drying to obtain black solids of PDA. Under vigorous stir, 20 mg polydopamine nanoparticles was dissolved in 10 mL of 0.1 M NaOH. Then we swiftly dropped 0.1 M HCl into the obtained solution to adjust the pH to 7.0 under sonication with an output power of 600 W for 2 min. We obtained a bright black polydopamine solution. The particles were retrieved by centrifugation with a centrifugal-filter (centrifugal filter device, MWCO = 30kDa) at 8000 rpm for 8 min and was washed several times with deionized water to remove the byproduct NaCl, followed by freeze-drying to obtain black solids of UPDA NPs.

Determination of RONS-scavenging capability. The evaluation of ABTS radical scavenging activity was based on a previously reported method¹⁶. Briefly, the ABTS radicals were generated by incubating 7 mM ABTS stock solution with 2.45 mM potassium persulfate in dark for 16 h. Then, the ABTS radical solution was diluted with PBS to reach an absorbance at 405 nm. 2 mL UPDA NPs solutions (0, 20, 40, 60 µg mL^− 1, respectively) were mixed with 2 mL ABTS solution and were placed in dark for 10 min. Then the absorbance at 405 nm was monitored with a UV-vis spectrophotometer. The ABTS radical scavenging abilities were calculated as follows:

ABTS scavenging ratio (%) = ((A_control-A_sample)/A_control) ×100;

where A_control is the absorbance of a standard solution without any radical scavengers, and A_sample is the absorbance after the reaction with the radical scavengers, respectively.

The SOD-like activity was determined using an SOD assay kit (WST-1 method) (Nanjing Jiancheng Bioengineering Institute, Nanjing, China). Briefly, O₂⁻ was generated through the oxidation of xanthine by xanthine oxidase (XO), which can convert WST-1 into formazan with a characteristic absorption at 450 nm. The formazan concentration was measured using a multiple plate reader.

The CAT-like activity was determined based on the H₂O₂ decomposition reaction. A tube containing 10 mM H₂O₂ and 0.1 mM CTPO in PBS was pumped with N2 for 10 min. Then, 50 µg mL^− 1 UPDA NPs was added and incubated for 5 min. ESR spectra were monitored at different time points. H₂O₂ of different concentrations (5–60 µM) was added to 100 µg mL^− 1 UPDA NPs. The final volume was adjusted to 3 mL, the absorbance value was measured at 640 nm and the dynamics curve was registered on a UV spectrophotometer. The steady-state kinetic assay was performed to confirm the CAT-like catalytic mechanism of UPDA NPs. The Michaelis-Menten constant (K_m) of UPDA NPs-catalyzed reaction was obtained by plotting the initial velocity versus H₂O₂ concentration. The maximum velocity V_max was calculated from the Lineweaver-Burk plot, where 1/V = 1/V_max + K_m (V_maxC).

The amount of •OH was measured with the Fenton reaction, in which •OH causes MB to oxidize and its color fading degree is proportional to the amount of •OH. Different concentrations of UPDA NPs (0, 45, 90 µg mL^− 1) were added to the •OH-MB reaction solution, and the absorbance at 664 nm was measured. The •OH-scavenging rate was obtained with the following equation:

Inhibition (%) = (A_control-A_sample)/A_sample,

where A_control is the absorbance of the control group, and A_sample is the absorbance of the UPDA NPs-treated group.

DPPH was used to evaluate the RNS scavenging activity of UPDA NPs. Different concentrations of UPDA (0, 5, 25, 100 µg mL^− 1) were mixed with 40 µM DPPH for 12 h and the absorbance spectra at 532 nm were recorded.

The ·NO-scavenging ability of UPDA NPs was tested by ESR using carboxy-PTIO as the trapper and the detection dye for ·NO. NOC18 was used as the source of ·NO. Carboxy-PTIO was dissolved in phosphate buffer (250 mM, pH 7.4), and NOC18 was dissolved in NaOH (1 mM). In a test tube, 0.5% methylcellulose was mixed with NOC18 (5 µM) for 30 min at room temperature, and the mixture was then added into the carboxy-PTIO solution (5 µM) in the absence or presence of UPDA NPs. The ESR spectra were then recorded. The ESR signal of carboxy-PTIO is characterized by five peaks. ·NO generated from NOC18 can reduce carboxy-PTIO into carboxy-PTI, which shows seven peaks of ESR signals. The reduction of carboxy-PTIO by ·NO will lead to a color change from purple to yellow. In addition, the ONOO- scavenging ability of UPDA NPs was evaluated by UV-vis spectroscopy using pyrogallol red as the indicator.

Animals. The animal experiments were performed in accordance with the guidelines of the Administrative Committee of Laboratory Animals. All the procedures involving animals were approved by Shanghai University Administrative Committee of Laboratory Animals (ECSHU 2021-039). A maximum of four mice per cage were kept on a 12-h light/dark cycle at a constant temperature (22°C) with food and water ad libitum. C57BL/6J mice of 26 weeks were used for DOX-induced senescent model. Mice were given two intraperitoneal injections of DOX at a dose of 10 mg/kg. All mice were kept in group housing until the start of the experiment and were then randomly assigned to control and experimental groups.

Biocompatibility and biosafety evaluation. C57BL/6J mice (2 months old, 20–25 g) were intravenously administrated with UPDA NPs at a single dose of 200 µL (100 µg mL^− 1). The mice injected with PBS were used as the control group. At day 30 post injection, the mice were anesthetized with intraperitoneal injection of chloral hydrate and sacrificed to harvest major organs (including heart, liver, spleen, lung, and kidney) for hematoxylin and eosin (H&E) staining and histological analysis. Mouse blood was collected through heart puncture. Routine blood parameters, including WBC, LYM, MON, GRA, MPV, RBC, HGB, MCH, HCT, RDWSD, MCV, MCHC, PLT, PDW and RDWCV, were analyzed on a Sysmex XS-800i automated hematology analyzer (Sysmex, Japan).

Transcriptomics analysis. DOX-induced senescent mice were randomly divided into two groups: the control group (n = 5) and the group treated with 100 µg mL^− 1 UPDA NPs at a dosage of 200 µL (experimental group, n = 5). After 24 h post injection, mice were sacrificed to collect the kidneys. Total RNA was extracted using TRIzol® Reagent (Invitrogen) according to the manufacturer’s instructions and genomic DNA was removed using DNase I (TaKara). Then RNA quality was determined by a 2100 Bioanalyser (Agilent) and quantified using an ND-2000 instrument (NanoDrop Technologies). Only high-quality RNA samples (OD260/280 = 1.8 ~ 2.2, OD260/230 ≥ 2.0, RIN ≥ 6.5, 28S:18S ≥ 1.0, > 1µg) were used to construct sequencing library. RNA-seq transcriptome library was prepared with a TruSeqTM RNA sample preparation Kit (Illumina, San Diego, U.S.A) using 1µg of total RNA. Briefly, messenger RNA with polyA tails was captured by oligo (dT) beads and was then fragmented in fragmentation buffer. Next, double-stranded cDNA was synthesized using a SuperScript double-stranded cDNA synthesis kit (Invitrogen, U.S.A) with random hexamer primers (Illumina). The synthesized cDNA was subjected to end-repair, phosphorylation and adenylation on the 3’ end. Libraries were enriched for cDNA fragments of 300 bp on 2% Low Range Ultra Agarose followed by PCR amplification using Phusion DNA polymerase (NEB) for 15 PCR cycles. After the quantification with a TBS380 fluorometer, paired-end RNA-seq sequencing library was sequenced with a HiSeq xten/NovaSeq 6000 sequencer (2 × 150bp read length, Illumina). The raw paired end reads were trimmed and subjected to quality control by SeqPrep (https://github.com/jstjohn/SeqPrep) and Sickle (https://github.com/najoshi/sickle) with default parameters. Then clean reads were separately aligned to reference genome with orientation mode using the HISAT2 software (http://ccb.jhu.edu/software/hisat2/index.shtml). The mapped reads of each sample were assembled by StringTie (https://ccb.jhu.edu/software/stringtie/index.shtml? t = example) in a reference-based approach. To identify DEGs between two different samples, the expression level of each transcript was calculated according to the transcripts per million reads (TPM) method. RSEM (http://deweylab.biostat.wisc.edu/rsem/) was used to quantify gene abundances. Differential expression analysis was performed using the DESeq2 package with |log2FC|>1 and Q value < = 0.05 as the criteria of DEGs. GO functional enrichment and KEGG pathway analyses were carried out using Goatools (https://github.com/tanghaibao/Goatools) and KOBAS (http://kobas.cbi.pku.edu.cn/home.do) with Bonferroni-corrected p-value ≤ 0.05 considered to be the threshold of enrichment. The PPI network of selected DEGs was constructed using the STRING database [PMID: 30476243] and was mapped with Cytoscape software (v 3.8.2).

Cell culture. The human embryonic renal epithelial 293T cell line was acquired from ATCC, and cultured in Dulbecco’s modified Eagle’s medium (Gibco, U.S.A) containing 10% fetal bovine serum (Gibco, U.S.A) and 1% s7 penicillin/streptomycin (Gibco, U.S.A) at 37°C with 5% CO₂. For DOX-induced senescence, 293T cells were treated twice with 0.2 mM DOX with a 2-day interval and were analyzed 7 days later. The expression of SA-β-GAL was detected by the cleavage of X-Gal. The levels of IL-6 and IL-1β were determined using commercially available kits and quantified from 3 replicates (n = 3).

Measurement of ROS scavenging activities in vitro. 293 T cells were seeded into 96-well and 24-well plates at a density of 1 × 10⁴ cells per well, and 1 × 10⁵ cells per well, respectively. After incubation for 24 h, cells were treated with 2×10^− 7 M DOX, 8g/L D-gal, or 250 µM H₂O₂ and 100 ug mL^− 1 UPDA NPs, and were further incubated at 37°C for a 2-day interval and analyzed 7 days later. For determining cell viability, cells seeded in 96-well plates were evaluated with cell counting kit-8 (CCK-8, Beyotime, China). Cells without the addition of UPDA NPs were regarded as the control. At least 50,000 cells were analyzed in each sample. For determining the ROS-scavenging effect of UPDA NPs (20 ug mL^− 1), DCF, an oxidation sensitive fluorescent dye, was used to detect the intracellular ROS level ⁶⁰. Briefly, DCFH-DA is a non-fluorescent chemical compound which can diffuse through the cell membrane freely and can be hydrolyzed by an intracellular esterase to generate DCFH. The non-fluorescent DCFH can be oxidized by the intracellular ROS to form fluorescent DCF. Therefore, the quantity of intracellular ROS is correlated with the fluorescent intensity of DCF. After the aforementioned incubation, cells were gently rinsed three times with serum-free medium to remove the free UPDA NPs. Then, a final concentration of 10 µM of DCFH-DA in serum-free medium was added to the cells and incubated in dark at 37°C for 30 min. Afterwards, the cells were washed with serum-free medium three times to remove unloaded DCFH-DA probe, imaged using a laser confocal microscope (Zeiss, Germany), and subjected to flow cytometry analysis.

Immunocytochemistry. Normal and DOX-induced senescent 293T cells were fixed with 4% paraformaldehyde (PFA) for 15 min, permeabilized with 0.2% Triton X-100 for 3 minutes and was then blocked with 10% (v/v) BSA in PBS for 2 h at room temperature or at 4℃overnight. Subsequently, the cells were washed with PBS three times and were then incubated with primary antibodies mouse anti-FOXO4 (1:500, Abcam, UK), rabbit anti-p16^ink4a (1:500, Abcam, UK), or rabbit anti-lamin B1 rabbit (1:500, Abcam, UK) for 2 h. The cells were then washed three times with PBS and incubated with secondary antibodies Goat anti-Mouse IgG (H + L) Alexa Fluor TM Plus 555 or goat anti-rabbit IgG (H + L) Alexa Fluor®488 at a dilution of 1:200 for 2 h. After washing three times with PBS, the cells were imaged on an inverted fluorescence microscope (Zeiss, Germany). The fluorescence intensity was obtained from 3 randomly selected regions of the cell culture to determine the expression levels of FOXO4, p16^ink4a and lamin B1 in each group.

Western blotting. 293T cells (1.0 × 10⁶) were collected and total protein was extracted with RIPA lysis buffer IV (Beyotime, China). The protein lysates were then separated by SDS-PAGE and transferred to polyvinylidene difluoride (PVDF) membranes. The membranes were then incubated with primary antibodies (diluted at 1:1000) against p21, lamin B1 or DcR2, and then with a horseradish-peroxidase conjugated secondary antibody (1:500). β-Actin (1:1000) was used as a loading control. Membranes were subsequently exposed according to manufacturer’s instructions (Western blot kit, Sangon Biotech Co., Ltd.). The band densities were quantified in ImageJ and normalized against GAPDH, representing the protein expression levels of p21, lamin B1 and DcR2.

Immunohistochemistry. The mice were anesthetized and perfused with PBS. The kidneys were collected, fixed with 4% PFA, and cut to obtain 30 µm sections using a vibratome (Invitrogen, U.S.A). After three rinses in PBS (5 min each), the sections were blocked in PBST (PBS + 0.3% Triton X-100) with 3% bovine serum albumin for 2 h, and were then incubated in primary antibodies (1:1000) at 4°C for 24 h, followed by three rinses in PBS (5 min each). Then, the sections were incubated with secondary antibodies (1:500) for 2 h at room temperature. After the incubation, the sections were washed with PBS for 5 min, and the nuclei were counterstained with DAPI for 10 min. Finally, the sections were washed in PBST and mounted in mounting medium. Fluorescence images were acquired with a 20× objective on a confocal microscope.

Flies were anesthetized with CO₂, dissected in PBS and fixed with 4% PFA at room temperature. Samples were incubated with anti-cleaved caspase-3 polyclonal antibody (1:500, Beyotime, China) and Alexa fluor 594 conjugated secondary antibody (1:500, Invitrogen), followed by DAPI staining and fluorescence imaging.

Determination of renal and hepatic function parameters. Blood samples were acquired from normal mice and DOX-induced senescent mice with or without the treatment of UPDA NPs for plasma separation. These samples were then centrifuged for 10 min at 1200 g. The supernatants were transferred into 1.5 mL tubes and recentrifuged for 5min at 1200 g. The supernatants were transferred again into 1.5 mL tubes for determining the levels CRE, BUN, ALT and AST.

Assessment of swimming performance. We monitored the swimming behavior of different mouse groups by continuously measuring their swimming speed. Swimming activity was recorded for 30 days.

Drosophila culture. Drosophila melanogaster (w1118) stocks were maintained and crossed according to standard laboratory procedures. Flies were raised under a 12/12 h, light/dark cycle at 25 ℃ with 60% humidity.

Measurement of ROS level in Drosophila. Different groups of Drosophila were sacrificed and washed with PBS. 50 mg of tissue was suspended in homogenate buffer A and was thoroughly homogenized with a glass homogenizer. The tissue homogenates were centrifuged at 100 g and 4°C for 3 min. The supernatant was collected for further experiments. For ROS level determination, 200 µL supernatant was added to a 96-well plate, and mixed with 2 µL DHE detection solution with a pipettor. The mixture was incubated at 37°C in dark for 30 min. The fluorescence intensity was measured in a fluorescence plate reader with an excitation wavelength of 488–535 nm and an emission wavelength of 610 nm. For determining the protein concentration, 50 µL supernatant was diluted 30 times with PBS and 100 µL diluent was subjected to Bradford protein assay. The ROS level is expressed as fluorescence intensity per mg protein.

Determination of lifespan and climbing ability of Drosophila. Newly eclosed wild-type female Drosophila were used for lifespan assay. 100 flies were used for each group. Flies were transferred for fresh food and the death number was recorded every day. Data were presented as survival curves and statistical analysis was performed with log-rank test. For climbing assay, eight male and eight female flies were placed in a plastic vial. The flies were gently knocked to the bottom of the vial before timing. Climbing distances within 4 s and 20 s were measured.

Statistical analysis. All quantitative results are shown as mean ± standard deviation. Statistical significance was determined using the likelihood ratio test for comparing the transcriptional levels of DEGs, the log-rank test for the lifespan assay of Drosophila and one-way ANOVA with Tukey’s post hoc test for all other experiments. The significance levels were set at *p < 0.05, **p < 0.01, ***p < 0.001 and ****p < 0.0001.

Data availability

The data that support the findings of this study are available within the paper and its supplementary information file or from the corresponding authors upon reasonable request.

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Acknowledgments

This work was financially supported by National Natural Science Foundation of China (Grant No. 52072393, 81971324, 81672313, 81700782), Shanghai Science and Technology Program (Grant No. 21010500100), Basic Research Program of Shanghai Municipal Government (Grant No. 21JC1406002), International Collaboration Project of Chinese Academy of Sciences (Grant No. GJHZ2072), Shanghai Science and Technology Committee Rising-Star Program (Grant No. 21QA1403100), National Key Research and Development Program of China (Grant No.2016YFA0101000, 2016YFA0101003, 2018YFA0109800, 2020YFA0113000, 2020YFA0113001).

Author contributions

Jiamei Han and Wei Feng conceived and designed the research. Jiamei Han synthesized and characterized the nanomaterials. Jiamei Han completed enzyme-like activity detection and RONS removal experiments. Jiamei Han conducted cell experiments. Hongwei Shi, Shibo Zhang, Wenjun Li, Cheng Zhuang and Linhua Gan assisted in the western blotting and immunofluorescence experiments. Jiamei Han conducted in vivo experiments. Jiao Wang and Hao Wu assisted in bioinformatics analysis. Jiamei Han analyzed the data. Jiamei Han wrote the paper. Jiamei Han, Wei Feng, Qian Li, Yu Chen, Holly M. Brown-Borg and Robert Chunhua Zhao are responsible for the final revision.

Competing interests

The authors declare no competing interests.

There is NO Competing Interest.

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Polydopamine nanomedicine-enabled antioxidation against senescence

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