Carbon dots nanozyme for anti-inflammatory therapy via scavenging intracellular reactive oxygen species

Quercetin-derived red emission carbon dots: A multifunctional theranostic nano-agent against Alzheimer's β-amyloid fibrillogenesis

Multifunctional agents with therapeutic and diagnostic capabilities are imperative to the prevention of Alzheimer's disease (AD), which is considered due to abnormal aggregation and deposition of β-amyloid protein (Aβ) as well as oxidative stress. Herein, quercetin (Que)- and p-phenylenediamine (p-PD)-derived red emission carbon dots (CDs) synthesized via a one-step hydrothermal method were designed as a novel theranostic nano-agent for the multi-target treatment of AD. R-CD-75 with an optimized composition exhibited significant inhibition of Aβ aggregation and rapid depolymerization of mature Aβ fibrils (<4 h) at micromolar concentrations (2 and 5 μg/mL, respectively). Moreover, R-CD-75 potently scavenged reactive oxygen species and showed turned-on red fluorescence imaging of Aβ plaques both in vitro and in vivo. In vitro assays proved that R-CD-75 significantly mitigated the Aβ-induced cytotoxicity and enhanced the cultured cell viability from 74.9 % to 98.0 %, while in vivo studies demonstrated that R-CD-75 prolonged the lifespan of AD nematodes by over 50 % (from 13 to 20 d). Compared to the precursors Que and p-PD, R-CD-75 inherited some of their structures and functional groups, such as aromatic structures, phenolic hydroxyl and amino groups, which were considered to interact with Aβ species through hydrogen bonding, electrostatic interactions, hydrophobic interactions, and π-π stacking, thus contributing to its effectiveness in its theranostic functions. This research has opened a new avenue to the development of potent theranostic agents by designing novel carbon dots.

Microwave-assisted synthesis, characterization and in vitro biomedical applications of Hibiscus rosa-sinensis Linn.-mediated carbon quantum dots

In recent years, carbon quantum dots (CQDs) have garnered considerable attention as a promising material for biomedical applications because of their unique optical and biological properties. In this study, CQDs were derived from the leaves of Hibiscus rosa-sinensis Linn. via microwave-assisted technique and characterized using different techniques such as ultraviolet-visible, Fourier transform infrared, fluorescence spectrometry, X-ray diffraction, dynamic light scattering, transmission electron microscopy and energy-dispersive X-ray spectroscopy. Subsequently, their potential for biomedical applications was investigated through in vitro assays assessing scratch healing, anti-inflammatory, antibacterial, and cytotoxicity properties. It was found that the CQDs were fluorescent, polycrystalline, quasi-spherical, ~ 12 nm in size with presence of -OH and -COOH groups on their negatively charged surfaces, and demonstrated good anti-inflammatory by inhibiting protein denaturation, cyclooxygenase-2 and regulating inflammatory cytokines. The CQDs also exhibited antimicrobial activity against Klebsiella pneumoniae and Bacillus cereus, good biocompatibility, along with excellent promotion of cell proliferation in vitro, indicating their potential as a anti-inflammatory and wound healing material. The properties were more enhanced than their precursor, H. rosa-sinensis leaf extract. Hence, the CQDs synthesized from the leaves of H. rosa-sinensis can serve as a potential biomedical agent.

Nanozymes sensor array for discrimination and intelligent sensing of phenolic acids in food

Although nanozymes sensor arrays have the potential to recognize multiple target substances simultaneously, they currently rarely identify phenolic acids in food due to limited catalytic performance and complex preparation conditions of nanozymes. Here, inspired by the structure of polyphenol oxidase, we have successfully prepared a novel gallic acid-Cu (GA-Cu) nanozyme with laccase-like activity. Due to the different catalytic efficiency of GA-Cu nanozymes towards six common phenolic acids, a three-channel colorimetric sensor array was constructed using reaction kinetics as the sensing unit to achieve high-throughput detection and identification of six phenolic acids within a concentration range from 1 to 100 μM. This method avoids the creation of numerous sensing units. Notably, the successful discrimination of six phenolic acids in samples of juice, beer, and wine has been achieved by the sensor array. Finally, aided by smartphones, a portable technique has been devised for the detection of phenolic acids.

Ultrahigh-Efficacy VEGF Neutralization Using Carbonized Nanodonuts: Implications for Intraocular Anti-Angiogenic Therapy

Ocular angiogenesis, associated with diseases such as retinopathy of prematurity and diabetic retinopathy, is a leading cause of irreversible vision loss. Herein, carbon nanodonuts (CNDs) with a donut-shaped structure are synthesized using sodium alginate (SA) and 1,8-diaminooctane (DAO) through a one-step thermal process. The formation of SA/DAO-CNDs occurs through a crosslinking reaction between SA and DAO, creating amide bonds followed by partial carbonization. In human retinal pigment epithelial cells exposed to H2 O2 or lipopolysaccharide, the SA/DAO-CNDs display a more than fivefold reduction in reactive oxygen species and proinflammatory cytokines, such as IL-6 and IL-1β, when compared to carbonized nanomaterials produced exclusively from SA. Furthermore, the CNDs effectively inhibit vascular endothelial growth factor A-165 (VEGF-A165 )-induced cell migration and tube formation in human umbilical vein endothelial cells due to their strong affinity for VEGF-A165 , with a dissociation constant of 2.2 × 10-14  M, over 1600 times stronger than the commercial drug bevacizumab (Avastin). Trypsin digestion coupled with LC-MS/MS analysis reveals that VEGF-A165 interacts with SA/DAO-CNDs through its heparin-binding domain, leading to activity loss. The SA/DAO-CNDs demonstrate excellent biocompatibility and potent anti-angiogenic effects in chicken embryos and rabbit eyes. These findings suggest that SA/DAO-CNDs hold promise as a therapeutic agent for treating various angiogenesis-related ocular diseases.

A guanosine/konjac glucomannan supramolecular hydrogel with antioxidant, antibacterial and immunoregulatory properties for cutaneous wound treatment

Developing naturally-derived wound dressing materials with intrinsic therapeutic effects is desirable for the clinical applications. Recently, guanosine-based supramolecular G-quadruplex (G4) hydrogel exhibited great potential in preparing biological materials due to its simple fabrication method and responsive gel networks. However, the weak mechanical properties and the consequent burst release of bioactive molecules restrict its clinical applications. Herein, we found that konjac glucomannan (KGM) with immunoregulatory effect did not affect the self-assembly of G-quadruplexes and thus effectively enhancing the mechanical properties of G4 hydrogel. Aloin, as a model drug, was in situ loaded into gel networks, finally obtaining the G4/Aloin-KGM hydrogel. This hydrogel exhibited porous morphology, swelling ability and hemostatic capability. Boronate bonds in G4 networks and aloin collectively endowed the hydrogel with excellent antioxidant performance. Meanwhile, aloin also provided outstanding in vitro and in vivo bactericidal ability. The wounds treated with this biocompatible hydrogel demonstrated faster regeneration of epithelial and dermal tissues, and the whole wound healing stages were accelerated by promoting collagen deposition, facilitating macrophage polarization towards M2 phenotype, down-regulating the expression level of IL-6, and up-regulating the expression level of IL-10, CD31 and α-SMA.

Carbon dots with selective fluorescence response to hydroxyl radical for sensitive detection of bleomycin

In this work, antioxidant carbon dots (ACDs) with high quantum yield (63.98%) were developed through a one-step strategy using citric acid, ethylenediamine, and L-arginine as sources. The ACDs demonstrated excellent in vitro antioxidant activity. Additionally, ACDs displayed a unique fluorescence response to hydroxyl radical (OH). Leveraging this distinctive feature, a selective and sensitive fluorescence-based sensor was developed for detecting bleomycin (BLM) in the presence of ferrous ions (Fe2+). The studies on the oxidizing properties and dynamic quenching mechanism of ACDs by OH suggested that OH reduced the contents of the amino and hydroxyl groups of ACDs, leading to a decreased electron cloud density of ACDs for dynamic quenching of ACDs. Under optimally refined conditions, the detection limit of this strategy for BLM was 0.58 μg/mL, with a linear range spanning from 1 to 24 μg/mL when employing ACDs as the probe. This fluorescence sensing strategy provides a promising method for the detection of BLM in clinical samples.

Solvent-Dependent Photoluminescence Emission and Colloidal Stability of Carbon Quantum dots from Watermelon Peels

Waste peels are considered an environmental burden and typically disposed in landfills. The aim of this study was to investigate the effects of various solvents on the luminescence properties of carbon quantum dots (CQDs). Watermelon peels were recycled and reuse as precursors for the synthesis of biomass CQDs via a green carbonization method. The colloidal stability, surface charge, and particle size were characterized using zeta potential and dynamic light scattering (DLS). DLS revealed that the size of the CQDs was approximately 5.80 ± 0.4 nm to 9.74 ± 0.8 nm. The high-resolution transmission electron microscopy (HRTEM) results demonstrated a correlation with the DLS results. The optical properties were characterized by photoluminescence (PL) and UV-Visible (UV-Vis) spectroscopy. PL measurements at different excitation wavelengths revealed that the CQDs emissions were influenced by the polarity of the solvents. Meanwhile, the Fourier transform infra-red (FTIR) results showed the presence of oxygen-containing groups on the surface of the CQDs. These results deepen our understanding of the solvent-dependent behavior and colloidal stability of the CQDs.

Reactive oxygen species (ROS) scavenging biomaterials for anti-inflammatory diseases: from mechanism to therapy

Inflammation is a fundamental defensive response to harmful stimuli, but the overactivation of inflammatory responses is associated with most human diseases. Reactive oxygen species (ROS) are a class of chemicals that are generated after the incomplete reduction of molecular oxygen. At moderate levels, ROS function as critical signaling molecules in the modulation of various physiological functions, including inflammatory responses. However, at excessive levels, ROS exert toxic effects and directly oxidize biological macromolecules, such as proteins, nucleic acids and lipids, further exacerbating the development of inflammatory responses and causing various inflammatory diseases. Therefore, designing and manufacturing biomaterials that scavenge ROS has emerged an important approach for restoring ROS homeostasis, limiting inflammatory responses and protecting the host against damage. This review systematically outlines the dynamic balance of ROS production and clearance under physiological conditions. We focus on the mechanisms by which ROS regulate cell signaling proteins and how these cell signaling proteins further affect inflammation. Furthermore, we discuss the use of potential and currently available-biomaterials that scavenge ROS, including agents that were engineered to reduce ROS levels by blocking ROS generation, directly chemically reacting with ROS, or catalytically accelerating ROS clearance, in the treatment of inflammatory diseases. Finally, we evaluate the challenges and prospects for the controlled production and material design of ROS scavenging biomaterials.

Carbon Dots' Potential in Wound Healing: Inducing M2 Macrophage Polarization and Demonstrating Antibacterial Properties for Accelerated Recovery

Bacterial infections and persistent inflammation can impede the intrinsic healing process of wounds. To combat this issue, researchers have delved into the potential use of carbon dots (CDs) in the regulation of inflammation and counteract infections. These CDs were synthesized using a microwave-assisted hydrothermal process and have demonstrated outstanding antibacterial and antibiofilm properties against Gram-positive and Gram-negative bacteria. Additionally, CDs displayed biocompatibility at therapeutic concentrations and the ability to specifically target mitochondria. CD treatment effectively nullified lipopolysaccharide-triggered reactive oxygen species production by macrophages, while simultaneously promoting macrophage polarization toward an anti-inflammatory phenotype (M2), leading to a reduction in inflammation and an acceleration in wound healing. In vitro scratch assays also revealed that CDs facilitated the tissue-repairing process by stimulating epithelial cell migration during reepithelialization. In vivo studies using CDs topically applied to lipopolysaccharide (LPS)-stimulated wounds in C57/BL6 mice demonstrated significant improvements in wound healing due to enhanced fibroblast proliferation, angiogenesis, and collagen deposition. Crucially, histological investigations showed no indications of systemic toxicity in vital organs. Collectively, the application of CDs has shown immense potential in speeding up the wound-healing process by regulating inflammation, preventing bacterial infections, and promoting tissue repair. These results suggest that further clinical translation of CDs should be considered.

The Potential of Novel Synthesized Carbon Dots Derived Resveratrol Using One-Pot Green Method in Accelerating in vivo Wound Healing

Background

Carbon dots (CDs), a novel nanomaterial, have gained significant attention over the past decade due to their remarkable fluorescence properties, low toxicity, and biocompatibility. These characteristics make them promising in various applications, especially in biomedicine. However, most CDs are currently synthesized using chemical materials, and their biocompatibility falls short of natural compounds. Research on extracting CDs from natural sources is limited, and their potential in biomedicine remains largely unexplored.

Methods

We extracted CDs from resveratrol, a natural plant compound, and enhanced their water solubility using citric acid. Characterization of resveratrol-based carbon dots (RES-CDs) was carried out using various techniques, including UV-Vis, SEM, TEM, FTIR, XRD, and fluorescence spectroscopy. Extensive biocompatibility tests, wound healing assays, cell migration studies, and angiogenesis experiments were conducted using human umbilical vein endothelial cells (HUVEC). In addition, we investigated the biocompatibility and wound healing potential of RES-CDs in an in vivo rat model of inflammation.

Results

RES-CDs exhibited stable yellow-green fluorescence under 365-nanometer ultraviolet light and demonstrated excellent biocompatibility. In wound healing experiments, RES-CDs outperformed resveratrol in terms of cell scratch healing, migration, and tube formation. In a rat skin defect model, RES-CDs promoted wound healing and stimulated the formation of blood vessels and tissue regeneration near the wound site, as evidenced by increased CD31 and VEGF expression.

Conclusion

Resveratrol-derived CDs with enhanced water solubility show superior performance in tissue healing compared to resveratrol. This discovery opens new possibilities for the clinical application of resveratrol-based carbon dots.

Anti-inflammatory potential of platinum nanozymes: mechanisms and perspectives

Inflammation is a complex process of the body in response to pathogen infections or dysregulated metabolism, involving the recruitment and activation of immune system components. Repeated dangerous stimuli or uncontrolled immune effector mechanisms can result in tissue injury. Reactive Oxygen Species (ROS) play key roles in physiological cell signaling as well as in the destruction of internalized pathogens. However, aberrant ROS production and release have deleterious effects on the surrounding environment, making ROS regulation a priority to reduce inflammation. Most of the current anti-inflammatory therapies rely on drugs that impair the release of pro-inflammatory mediators. Nevertheless, increasing the enzymatic activity to reduce ROS levels could be an alternative or complementary therapeutic approach to decrease inflammation. Nanozymes are nanomaterials with high catalytic activity that mimic natural enzymes, allowing biochemical reactions to take place. Such functional particles typically show different and regenerable oxidation states or catalytically reactive surfaces offering long-term activity and stability. In this scenario, platinum-based nanozymes (PtNZs) exhibit broad and efficient catalytic functionalities and can reduce inflammation mainly through ROS scavenging, e.g. by catalase and superoxide dismutase reactions. Dose-dependent biocompatibility and immune compatibility of PtNZs have been shown in different cells and tissues, both in vitro and in vivo. Size/shape/surface engineering of the nanozymes could also potentiate their efficacy to act at different sites and/or steps of the inflammation process, such as cytokine removal or specific targeting of activated leukocytes. In the present review, we analyze key inflammation triggering processes and the effects of platinum nanozymes under exemplificative inflammatory conditions. We further discuss potential platinum nanozyme design and improvements to modulate and expand their anti-inflammatory action.

N-Acetylcysteine-Derived Carbon Dots for Free Radical Scavenging in Intervertebral Disc Degeneration

Intervertebral disc degeneration (IVDD) is associated with oxidative stress induced reactive oxygen species (ROS) dynamic equilibrium disturbance. Nanozymes, as nanomaterials with enzyme-like activity, can regulate intro-cellular ROS levels. In this study, a new carbon dots nanozyme, N-acetylcysteine-derived carbon dots (NAC-CDs), is developed and proved to be an ideal antioxidant and anti-senescent agent in IVDD management. The results confirmed the NAC-CDs have satisfactory biocompatibility and strong superoxide dismutase (250 U mg-1 ), catalase, glutathioneperoxidase-like activity, and total antioxidant capacity. Then, the powerful free radical scavenging and antioxidant ability of NAC-CDs are demonstrated in vitro as observing the reduced ROS in H2 O2 induced senescent nucleus pulposus cells (NPCs), in which the elimination efficiency of toxic ROS is more than 90%. NAC-CDs also maintained mitochondrial homeostasis and suppressed cellular senescence, subsequently inhibited the expression of inflammatory factors in NPCs. In vivo, evaluations of imaging and tissue morphology assessments suggested that disc height index, magnetic resonance imaging grade and histological score are significantly improved from the degenerative models when NAC-CDs is applied. In conclusion, the study developed a novel carbon dots nanozyme, which efficiently rescues IVDD from ROS induced NPCs senescence and provides a potential strategy in management of IVDD in clinic.

Carbon Dots for the Treatment of Inflammatory Diseases: An Appraisal of In Vitro and In Vivo Studies

In recent decades, several studies demonstrating various applications of carbon dots (C-dots), including metal sensing, bioimaging, pH sensing, and antimicrobial activities, have been published. Recent developments have shifted this trend toward biomedical applications that target various biomarkers relevant to chronic diseases. However, relevant developments and research results regarding the anti-inflammatory properties of C-dots against inflammation-associated diseases have not been systematically reviewed. Hence, this review discusses the anti-inflammatory effects of C-dots in in vivo and in vitro models of LPS-induced inflammation, gout, cartilage tissue engineering, drug-induced inflammation, spinal cord injury, wound healing, liver diseases, stomach cancer, gastric ulcers, acute kidney and lung injury, psoriasis, fever or hypothermia, and bone tissue regeneration. The compiled studies demonstrate the promising potential of C-dots as anti-inflammatory agents for the development of new drugs.