Bioinspired Metal-Free Fluorescent Carbon Nanozyme with Dual Catalytic Activity to Confront Cellular Oxidative Damage

Transferrin Immobilized Graphene Oxide Nanocomposite for Targeted Cancer Chemodynamic Therapy via Increasing Intracellular Labile Fe2+ Concentration

Recently, different alternative regulated cell death (RCD) pathways, viz., necroptosis, pyroptosis, ferroptosis, cuproptosis etc., have been explored as important targets for the development of cancer medications in recent years, as these can change the immunogenicity of the tumor microenvironment (TME) and will finally lead to the inhibition of cancer progression and metastasis. Here, we report the development of transferrin immobilized graphene oxide (Tfn@GOAPTES) nanocomposite as a therapeutic strategy toward cancer cell killing. The electrostatic immobilization of Tfn on the GOAPTES surface was confirmed by different spectroscopy and microscopy techniques. The Tfn immobilization was found to be ∼74 ± 4%, whereas the stability of the protein on the GO surface suggested a robust nature of the nanocomposite. The MTT assay suggested that Tfn@GOAPTES exhibited cytotoxicity toward HeLa cells via increased lipid peroxidation and DNA damage. Western blot studies resulted in decreased expression of acetylation on lysine 40 of α-tubulin and increased expression of LC3a/b for Tfn@GOAPTES treated HeLa cells, suggesting autophagy to be the main cause of the cell death mechanism. Overall, we predict that the present approach can be used as a therapeutic strategy for cancer cell killing via selective induction of a high concentration of intracellular iron.

Revitalizing Ancient Mitochondria with Nano-Strategies: Mitochondria-Remedying Nanodrugs Concentrate on Disease Control

Mitochondria, widely known as the energy factories of eukaryotic cells, have a myriad of vital functions across diverse cellular processes. Dysfunctions within mitochondria serve as catalysts for various diseases, prompting widespread cellular demise. Mounting research on remedying damaged mitochondria indicates that mitochondria constitute a valuable target for therapeutic intervention against diseases. But the less clinical practice and lower recovery rate imply the limitation of traditional drugs, which need a further breakthrough. Nanotechnology has approached favorable regiospecific biodistribution and high efficacy by capitalizing on excellent nanomaterials and targeting drug delivery. Mitochondria-remedying nanodrugs have achieved ideal therapeutic effects. This review elucidates the significance of mitochondria in various cells and organs, while also compiling mortality data for related diseases. Correspondingly, nanodrug-mediate therapeutic strategies and applicable mitochondria-remedying nanodrugs in disease are detailed, with a full understanding of the roles of mitochondria dysfunction and the advantages of nanodrugs. In addition, the future challenges and directions are widely discussed. In conclusion, this review provides comprehensive insights into the design and development of mitochondria-remedying nanodrugs, aiming to help scientists who desire to extend their research fields and engage in this interdisciplinary subject.

Specializing Carbon Nanozyme Active Sites for Sensitive Alkaline Phosphatase Activity Metal-Free Detection

As biological enzymes regulate metabolic processes, alkaline phosphatase (ALP) is a critical diagnostic indicator associated with many diseases. To accurately measure the enzyme activity, nanozymactic materials can offer sensitive strategies for ALP detection. However, nanozymes often lack specific target binding sites, and the presence of common co-components, e. g., metal ions, may cause false-positive or false-negative results in enzyme activity determination. Herein, we developed a colorimetric assay for ALP detection using metal-free nanozymatic carbon dots (CDs). The ALP hydrolysis of pyrophosphate ions (PPi) to phosphate ions (Pi) induces a "turn-on" response based on the nanozyme activity. This PPi-induced inhibition mechanism is extensively studied via the Michaelis-Menten model, revealing that PPi acts as a noncompetitive inhibitor for CDs at a binding site distinct from the common nanozyme active site. With superior responses to ALP substrates, a highly sensitive and selective method is established for sensing ALP activity with a linear range of 0.010-0.200 U/L and a detection limit of 0.009 U/L. This finding explores the recognition and binding behavior of nanozymes, allowing for precise and reliable measurements even in complex samples, and represents a significant breakthrough for nanozyme-based assays in biological analysis.

Carbon nanosphere based bifunctional oxidoreductase nano-catalytic agent to mitigate hypoxia in cancer cells

Developing metal-free carbon nanozyme for tumor hypoxia is difficult. In biomedical applications, especially in the case of biomolecular detection, extensive research has been done on nanozymes with enzyme-mimicking catalytic activity. However, there are considerably fewer investigations on targeted nano-catalytic tumor therapy. Nano catalytic medicine-enabled chemotherapy is a safe and promising treatment strategy that involves the conversion of excess H₂O₂ into O₂ in a tumor environment. Here we have synthesized carbon nanosphere (CNS) using the Camellia sinensis plant (CS-CNS). Further surface functionalization was achieved via nitrilotriacetic acid conjugation (NTA@CS-CNS). A stability study of synthesized nanozyme in the presence of various cations, anions, and 5 different pH range suggested the robustness of carbon based nanoassembly. The catalytic in vitro study shows that NTA@CS-CNS mimics peroxidase and catalase using TMB and H₂O₂ as substrates. NTA@CS-CNS showed K_m and V_max values of ~ 193.2 μM and 0.43 μM/s, ~ 413 μM and 1.42 μM/s, and ~ 378 μM and 1.63 μM/s, respectively when H₂O₂ and TMB was used for CAT and POD activity. Results showed that NTA@CS-CNS in combination with SFN and laser irradiation reduces hypoxia. Hence, our study could pave the path for the development of different non-toxic nano catalytic therapy for tumors in cancerous cells.

Carbon nanoparticles induce DNA repair and PARP inhibitor resistance associated with nanozyme activity in cancer cells

Background

Quantum nanodots especially carbon nanoparticles (CNPs) have been widely studied in biomedicine in imaging, and drug delivery, but anti-cancer mechanisms remain elusive.

Methods

Here, we investigated a type of cell death induced by food (beet, soybean) derived CNPs in cancer cells and tested whether CNPs induced DNA damage and resistant to anti-cancer agent PARP inhibitor (PARPi) could be overcome by quantum calculations, TEM, AFM, FT-IR, soft agar assay, and cytotoxicity assay.

Results

At high doses, CNPs derived from beet lead to a pop-like apoptosis (Carbopoptosis) in cancer cells. Quantum mechanical calculations confirmed CNPs binding with phosphate groups as well as DNA bases. At low doses, CNPs develop PARPi drug resistance through interactions between CNPs and PARPi. A synergistic drug effect was achieved with the combination of phosphatase inhibitor (PPi), PARPi, and CNPs. This is corroborated by the fact that sulfur modulated CNPs which exhibit super high phosphatase nanozyme activity abrogated the CNPs induced colony formation in anchorage-independent cancer cell growth.

Conclusion

Thus, our data suggest the CNPs intrinsic nanozyme activity of phosphatase may crosstalk with drug resistance, which can be reversed upon modulations.

Single-walled carbon nanotube conjugated cytochrome c as exogenous nano catalytic medicine to combat intracellular oxidative stress

Mitochondrial dysfunction has been reported to be one of the main causes of many diseases including cancer, type2 diabetes, neurodegenerative disorders, cardiac ischemia, sepsis, muscular dystrophy, etc. Under in vitro conditions, Cytochrome C (Cyt C) maintains mitochondrial homeostasis and stimulates apoptosis, along with being a key participant in the life-supporting function of ATP synthesis. Hence, the medicinal importance of Cyt C as catalytic defense is immensely important in various mitochondrial disorders. Here, we have developed a nanomaterial via electrostatically conjugating oxidized single-wall carbon nanotube with Cyt C (Cyt C@cSWCNT) for the exogenous delivery of Cyt C. The chemical and morphological characterization of the developed Cyt C@cSWCNT was done using UV-vis, FTIR, XPS, powder XRD, TGA/DSC, TEM, etc. The developed Cyt C@cSWCNT exhibited bifunctional catalase and peroxidase activity with K_m (∼ 642.7 μM and 351.6 μM) and V_max (∼0.33 μM/s and 2.62 μM/s) values, respectively. Also, through this conjugation Cyt C was found to retain its catalytic activity even at 60 °C, excellent catalytic recyclability (at least up to 3 times), and wider pH activity (pH = 3 to 9). Cyt C@cSWCNT was found to promote intracellular ROS quenching and maintain mitochondrial membrane potential and cellular membrane integrity via Na⁺/K⁺ ion homeostasis during the H₂O₂ stress. Overall the present strategy provides an alternative approach for the exogenous delivery of Cyt C which can be used as nano catalytic medicine.

Facile synthesis of biogenic silica nanomaterial loaded transparent tragacanth gum hydrogels with improved physicochemical properties and inherent anti-bacterial activity

In this report, biogenic, crystalline (∼60.5 ± 2%) bowknot structured silica nanoparticles (BSNPs) of length ∼ 274 ± 7 nm and width ∼ 36 ± 2 nm were isolated from invasive species viz. Lantana camara. These were then chemically modified using nitrogen containing moieties viz. APTES and CTAB. These modified BSNPs were then used as electrostatic cross-linking agents for the formation of tragacanth gum (TG) hydrogels. The cytocompatible CTAB@BSNP-TG hydrogels documented ∼10-12 fold enhancement in anti-bacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa when compared with TG hydrogels. Disruption of the bacterial membrane by ROS generation and protein leakage were responsible for anti-bacterial activity. A cell migration assay suggested that CTAB@BSNP-TG augmented the cell proliferation of NIH-3T3 cells compared to other TG hydrogels. The present study will pave the path for the development of organic-inorganic hybrid nanocomposite-based hydrogels for anti-bacterial and cell migration applications.

Protein-Cloaked Nanoparticles for Enhanced Cellular Association and Controlled Pathophysiology via Immunosurveillance Escape

Weak interactions play an important role in soft corona (SC) formation and thus help in evaluating the biological fate of the nanoparticles (NPs). Preadsorption of specific proteins on the NP surface, leading to SC formation, has been found to help NPs in evading immunosurveillance. However, the role of different preadsorbed biomolecules in determining the NP pathophysiology and cellular association, upon their re-exposure to in vivo conditions, still remains elusive. Here, differently charged gold NPs were precoated with two different blood components, viz. red blood cells and human serum albumin protein, and these were then re-exposed to human serum. Cloaking NPs with protein improved the NP colloidal stability and other physico-chemical properties along with increased cellular association. Detailed proteomic analysis suggested that protein-camouflaged NPs showed a decrease in immune-responsive proteins compared to their bare counterparts. Further, it was also observed that the secondary protein signature on the NP surface was governed by primary protein coating; however, the event was more or less NP charge-independent. This study will pave the path for future strategies to make NPs invincible to the immunosurveillance system of the body.

DNA damage response proteins synergistically affect the cancer prognosis and resistance

Amplification of oxidative stress can be utilized as a strategy to attenuate cancer progression by instigating apoptosis. However, the duration of positive response to such therapies is limited, as cancer cells eventually develop resistance. The underlying molecular mechanisms of cancer cells to escape apoptosis under oxidative stress is unknown. Employing big data, and its integration with transcriptome, proteome and network analysis in six cancer types revealed system-level interactions between DNA damage response (DDR) proteins, including; DNA damage repair, cell cycle checkpoints and anti-apoptotic proteins. Cancer system biology is used to elucidate mechanisms for cancer progression, but networks defining mechanisms causing resistance is less explored. Using system biology, we identified DDR hubs between G1-S and M phases that were associated with bad prognosis. The increased expression of DDR network was involved in resistance under high oxidative stress. We validated our findings by combining H₂O₂ induced oxidative stress and DDR inhibitors in human lung cancer cells to conclude the necessity of targeting a 'disease-causing network'. Collectively, our work provides insights toward designing strategies for network pharmacology to combat resistance in cancer research.

A pH-Responsive Persistent Luminescence Nanozyme for Selective Imaging and Killing of Helicobacter pylori and Common Resistant Bacteria

Helicobacter pylori (H. pylori) infection is implicated in the etiology of many diseases. H. pylori eradication by antibiotic therapy is limited by the extreme acidic environment in the stomach, the undesired side effect of intestinal commensal bacteria, and the development of drug resistance. Here, we report a pH-responsive persistent luminescence (PL) nanozyme (MSPLNP-Au-CB) for in vivo imaging and inactivation of H. pylori. This PL nanozyme is composed of mesoporous silica (MS)-coated persistent luminescence nanoparticles (MSPLNP), Au nanoparticles (AuNP), and chitosan-benzeneboronic acid (CB), taking advantage of the long PL of PLNP to realize autofluorescence-free imaging, the pH-activated oxidase- and peroxidase-like nanozyme activity of AuNP, and the bacterial binding capacity of CB. The MSPLNP-Au-CB nanozyme can resist the corrosion of gastric acid and exhibit pH-activated dual nanozyme activity to catalyze bactericidal reactive oxygen species generation. This multifunctional nanozyme enables targeted imaging and activated deactivation of H. pylori under extreme gastric acid conditions as well as methicillin-resistant Staphylococcus aureus in common slightly acidic environments, while it has no side effects on the commensal bacteria and normal cells in normal physiological environments. This work provides a promising PL nanozyme platform for bioimaging and therapy of bacterial infection under harsh conditions.

Progress and Perspective on Carbon-Based Nanozymes for Peroxidase-like Applications

Tumor microenvironment-responsive chemodynamic therapy (CDT), an approach based on Fenton/Fenton-like reaction to convert hydrogen peroxide (H₂O₂) into the highly cytotoxic hydroxyl radical (·OH) in situ to kill cancer cells, represents an important direction for cancer therapy. Different types of nanozymes (nanomaterial-based catalysts that can mimic the activities of natural enzymes) have been developed to mimic peroxidase. This Perspective highlights the latest research progress regarding low-cost and biocompatible carbon-based nanozymes for peroxidase mimics. The effects of structure and surface properties of carbon-based nanozymes on their electronic transfer and peroxidase-like activity are analyzed, including nanospheres, nanotubes, nanosheets, and graphene quantum dots (GQDs) with or without surface functionalization and heteroatom doping. We expand our newly developed carbon nitride (g-C₃N₄) QD systems to nanozyme application, which are highly efficient in converting the intracellular H₂O₂ to ·OH species to kill 4T1 cancer cells and demonstrate a great potential for CDT.

Nanozymes-Hitting the Biosensing "Target"

Nanozymes are a class of artificial enzymes that have dimensions in the nanometer range and can be composed of simple metal and metal oxide nanoparticles, metal nanoclusters, dots (both quantum and carbon), nanotubes, nanowires, or multiple metal-organic frameworks (MOFs). They exhibit excellent catalytic activities with low cost, high operational robustness, and a stable shelf-life. More importantly, they are amenable to modifications that can change their surface structures and increase the range of their applications. There are three main classes of nanozymes including the peroxidase-like, the oxidase-like, and the antioxidant nanozymes. Each of these classes catalyzes a specific group of reactions. With the development of nanoscience and nanotechnology, the variety of applications for nanozymes in diverse fields has expanded dramatically, with the most popular applications in biosensing. Nanozyme-based novel biosensors have been designed to detect ions, small molecules, nucleic acids, proteins, and cancer cells. The current review focuses on the catalytic mechanism of nanozymes, their application in biosensing, and the identification of future directions for the field.