Nanomedicine-based modulation of redox status for cancer therapy

Redox species-responsive nanoplatforms for O₂ or other toxic ROS generation

Considered as a hallmark of malignancies, H₂O₂ which has high stability in the TME, has been employed as a stimulus in nanomaterial drug delivery systems. Meanwhile, GSH at high concentrations maintains the redox balance and can be used in the design of GSH-responsive nanoplatforms for cancer therapy. H₂O₂ not only functions as a signaling molecule to mediate cellular movements, but also can be decomposed to in situ O₂ or other toxic ROS under certain conditions, thus enhancing therapeutic efficacy. Depletion of GSH plays a significant role in redox stress elevation, relying on the Fenton reaction, due to its main function of scavenging ROS.^[27] Additionally, redox species-sensitive nanoparticles cannot only achieve drug delivery but also offer bioimaging applications. In addition, many nanoparticles have been designed to respond to redox species to activate their function or release incorporated drugs.

To date, multiple nanoplatforms have been designed to decompose H₂O₂ to O₂ for alleviating hypoxia in the TME or converting H₂O₂ into highly toxic ˙OH or ¹O₂ for excessive oxidative stress. An H₂O₂-responsive degradable nanoplatform (MDSP NP) was created, for instance, by co-loading doxorubicin (DOX), aza-BODIPY (SAB) and a photosensitizer (PS) into MnO₂ NPs with a hydrangea structure.^[28] In this system, MnO₂ can produce oxygen and alleviate tumor hypoxia by reacting with H₂O₂ and H⁺ in the TME. The in vitro and in vivo data showed that MDSP NPs could be paired with laser radiation to produce an outstanding anti-tumor impact that was synergistic with chemo/photodynamic/photothermal treatment. Moreover, TME facilitates the generation of highly toxic ˙OH converted from H₂O₂ in the presence of metal ions such as ferrous (Fe²⁺) and cupric (Cu²⁺) due to its mild acidity and overproduced H₂O₂. Fenton or Fenton-like reactions are what these are called. By using a hydroxide ion to coordinate H₂O₂ to Cu²⁺, Lin et al. created a copper peroxide (CP) nanodot, for instance.^[29] The release of Fenton catalytic Cu²⁺ and H₂O₂ as well as a Fenton-type reaction for the conversion of H₂O₂ into extremely poisonous ˙OH were both enhanced by the acidic environment of endo/lysosomes in tumor cells. The resultant ˙OH caused cell death via a lysosome-associated route by inducing lysosomal membrane permeabilization by lipid peroxidation. With the development of H₂O₂ responsive-nanoplatforms or nanomaterials with CAT mimicking activity, multiple antitumor strategies that require the presence of O₂ including photodynamic therapy (PDT), chemodynamical therapy (CDT) and sonodynamic therapy (SDT) have achieved better antitumor effects (the mechanism and effect of their action are described in detail below). Moreover, the generation of O₂ in situ by catalyzing H₂O₂ could overcome tumor hypoxia-associated drug resistance.

Developing nanoagents that can efficiently break redox homeostasis by reducing tumor GSH levels has also emerged as an efficient tumor therapy. Generally, multivalent metal ions such as Fe³⁺/Fe²⁺, Cu²⁺/Cu⁺, Mn⁴⁺/Mn²⁺ and Co³⁺/Co²⁺ exhibit GSH-responsive via a valence shift.^[30] An illustration is a novel albumin-based multifunctional nanoagent for GSH-depletion that was created by co-growing CuO and MnO_X inside of albumin molecules and then conjugating the resulting nanoagent with a Pt^IV prodrug. Copper species can produce ˙OH in weakly acidic conditions (pH = 6.5), whereas MnO_X can interact with GSH and deplete it, reducing the synthesis of GSH-Pt adducts and ˙OH consumption. Thus, this system can inhibit GPX-4 expression and achieve better chemotherapy and chemodynamic therapy effects.^[31] Gong et al. designed a nanomedicine by anchoring gold onto a carbon-dot (CAT-g), followed by conjunction with triphenylphosphine (TPP) and cinnamaldehyde (CA) on its surface to disturb mitochondrial redox homeostasis.^[32] After the liberation of CA in response to the acidity of the endosomes, TPP-CAT-g quickly reacted with mitochondrial GSH and elevated ROS production. These data showed that MitoCAT-g treatment significantly inhibits tumor growth in subcutaneous and orthotopic patient-derived xenograft (PDX) hepatocellular carcinoma models, indicating that MitoCAT-g is a promising agent for anticancer applications.

Clearly, oxidative stress might be effectively increased to boost therapeutic effects in cancer treatment by simultaneously increasing ROS levels and depleting GSH. Mesoporous copper/manganese silicate nanospheres (mCMSNs) coated with cancer cell membranes were developed by Liu et al. to convert endogenous H₂O₂ into O₂ and then react with O₂ to create harmful ¹O₂.^[33] While this is going on, Cu⁺, Mn²⁺ and ˙OH can be produced by the Fenton-like reaction that is catalyzed by the GSH-triggered degradation of mCMSNs. They showed that by converting endogenous H₂O₂ into O₂ and then reacting with O₂ to produce harmful ¹O₂ when exposed to a 635 nm laser, mCMSNs might alleviate the tumor hypoxic microenvironment. For effective hydroxyl radical (˙OH) formation, GSH-triggered mCMSNs biodegradation can simultaneously produce Fenton-like Cu⁺ and Mn²⁺ ions and deplete GSH. This simultaneous hypoxia relieving and GSH depletion system disrupts the cellular antioxidant defense system, thus exhibiting exceptional anti-tumor therapeutic effects. Through the coprecipitation of upconversion nanoparticles (UCNPs) and AIE-active photosensitizers, followed by the formation of MnO₂ as the outer shell, Wang et al. created a GSH-depleting and near-infrared (NIR)-regulated nanoplatform.^[34] UCNPs in this system cause the activation of AIE-active photosensitizers to produce ˙OH under exposure to NIR irradiation. The MnO₂ shell was decomposed to Mn²⁺ by intracellular GSH, which efficiently depletes GSH and elevates intracellular ˙OH. Notably, the resulting Mn²⁺ was subsequently capable of catalyzing intracellular H₂O₂ to ˙OH. As a result, tumor growth was significantly inhibited by this triple-jump ˙OH generation protocol with no noticeable side effects.

Redox species-responsive nanoplatforms for bioimaging

Redox species-sensitive nanoparticles cannot only deliver cytotoxic drugs but also provide bioimaging applications. The bioimaging of H₂O₂-responsive theranostics is mainly achieved by the quench of H₂O₂-sensitive fluorescent dyes. Nanomaterials containing metal ions,^[35] arylboronic ester^[36] and aryl oxalate ester^[37] have been reported for bioimaging. An example is the Cu/CC NPs, which are synthesized by assembling a photosensitizer (Chlorine e6, Ce6) and modified carbon dots (CDs-Ce6) and Cu²⁺ and exhibit quenched fluorescence (FL) imaging and photosensitization. In addition, Cu²⁺ not only reacts with H₂O₂ to provide extra chemodynamic therapy (CDT) but also depletes GSH in tumors, thus enhancing the efficacy of ROS based therapy.^[38] Recently, photoacoustic imaging (PAI) has emerged as a promising imaging modality for cancer diagnosis due to its good penetration into deep tissue and fine spatial solubility. A graphene quantum dot nanozyme (GQDzyme)/2,2′-azino-bis (ABTS) based exosome-like nanozyme vesicle was developed by Ding et al.^[39] In the presence of H₂O₂, the GQDzyme effectively catalyzes ABTS into its oxidized form, which is an ideal contrast agent for PAI due to its strong NIR absorbance. Their research suggested that this exosome-like nanozyme vesicle, with excellent biocompatibility and blood circulation stealth ability, effectively accumulated and selectively triggered catalytic PAI in nasopharyngeal carcinoma (NPC). To further achieve imaging-guided tumor-targeted effective PDT, Zeng et al. reported a novel H₂O₂-activatable and biodegradable nanomedicine (BSA-MBPB) that encapsulates pro-photosensitizer (MBPB) into bovine serum albumin (BSA) with its photoactivity completely ablated within BSA.^[40] H₂O₂ activates BSA-MBPB to not only produce the photosensitizer methylene blue for recovering its fluorescent for dual-modal imaging (photoacoustic and photosensitizing) and cytotoxic singlet oxygen (¹O₂) generation, but also provide adjuvant quinone methide to boost the ¹O₂ by GSH-depletion.

Studies have also suggested that the redox reaction between nanoplatforms and GSH provides bioimaging applications for diagnosis and treatment of cancer. Multiple imaging modalities with GSH-responsiveness such as MRI, computed tomography, optical imaging and upconversion luminescence (UCL) have been employed in the preclinic and clinic. For instance, He et al. reported on a drug delivery system that targets the mitochondria and is designated as CDs (DOX)@MSN-TPP@AuNPs.^[41] This mesosystem worked as a promising fluorescent probe (λex = 633 nm, λem = 650 nm) for targeted imaging of mitochondria using NIR fluorescence to increase therapeutic effectiveness and safety after being etched with GSH. In the meantime, mitochondrial depolarization and subsequent death can be induced in cells by the release of DOX in a GSH-dependent manner. Xu et al. designed a nanoagent based on the inherent UCL/CT/MRI abilities of upconversion nanoparticles (UCNPs) for imaging-guided therapy.^[42] By rupturing the brittle Mn-O link and releasing Mn under acidic and high GSH conditions, the MRI effect was achieved. Additionally, this nanoagent was given numerous imaging capabilities to realize imaging-guided cancer therapy thanks to MRI/CT/UCL imaging produced from Gd³⁺/Yb³⁺/Nd³⁺/Er³⁺ co-doped UCNPs under 808 nm laser excitation. Overall, by combining monitoring tumor uptake and drug liberation on one platform, various imaging modality based nanotheranostic agents are anticipated to perform well in cancer therapy.

Redox species-responsive nanoplatforms for cargo release and prodrug activation

In addition to the above-mentioned applications, redox species can serve as a stimulus to activate the controllable release of drugs from nanosystems.^[43] For instance, a ROS-triggered prodrug nanoplatform was created by pyropheophorbide-induced self-assembly of CTX-S-OA or CTX-Se-OA into nanoparticles (PPa).^[44] CTX was selectively and rapidly released in response to not only H₂O₂ in tumor tissue, but also PPa generated ROS under laser irradiation. The tumor distribution and systemic circulation of both CTX and PPa were also greatly prolonged by this prodrug-nano combination, showing promising synergistic therapeutic effects in vivo. Lee et al. have prepared PL-incorporated ChitoPEGse nanoparticles to target pulmonary metastasis of cancer cells by crosslinking selenocystine-acetyl histidine (Ac-histidine) with methoxy poly(ethylene glycol)-grafted chitosan (ChitoPEG) for delivery of piperlongumine (PL, a natural alkaloid).^[45] In their investigation, PL showed superior anticancer and antimetastatic efficacy in vitro and in vivo and was released in response to H₂O₂ and acidic stimulation. Taken together, nanoplatforms containing H₂O₂-responsive moieties hold promise in stimuli-driven drug release.^[46]

Nanoplatforms containing GSH-activated prodrug/cargoes have also been found to improve drug release and chemotherapeutic effectiveness. A pH/reductive dual-sensitive polymeric prodrug (P(OE DS-CP)) was created in 2019 by He et al. through condensation of cisplatin derivatives (Pt^IV) with an ortho ester monomer.^[47] Prodrugs have the potential to self-assemble into micelles, load DOX and then form a synergistic drug delivery system. To release CDDP quickly and completely and DOX into tumor cells, the polymer backbone might be broken down at a low pH in the high GSH TME. In vitro and in vivo studies revealed that the DOX-loaded micelles could be triggered to release two drugs into tumor tissues which exhibited synergistic antitumor effects. Additionally, GSH has the ability to break numerous redox-sensitive chemical bonds, including disulfide bonds (–S–S–), diselenide bonds (–Se–Se–) and carbon–diselenide bonds (–C–Se–), resulting in the disintegration of nanostructures and the targeted release of drugs at the tumor site.^[48] For instance, a stimulus-responsive silica nanoparticle (SNP) integrated with a disulfide crosslinker for GSH-responsive cargo release capability incorporating an imidazole-containing component for endosomal escape capability was reported.^[49] Multiple cargos such as nucleic acids (e.g. DNA and mRNA) and CRISPR genome editors (e.g. Cas9/sgRNA ribonucleoprotein (RNP), and RNP with donor DNA) can be delivered by this SNP with excellent efficiency and biocompatibility to target cancer cells. Overall, these studies suggest an exciting strategy for specific drug release in the tumor.

Nanoparticle-mediated suspension of moderate oxidative stress for cancer therapy

By promoting numerous biochemical processes including signal transduction, autophagy and proteolysis, moderate ROS has been shown to assist the physiological functions of various diseases, including cancer. Scavenging pro-tumor ROS in this situation has the potential to lower the risk of cancer and slow the spread of the disease. Obviously, direct delivery of ROS inhibitors such as N-acetyl-l-cysteine (NAC), sodium azide (NaN₃) and mannitol, as well as those agents that could inhibit ROS production by targeting related signaling pathways or node molecules possess huge potential to inhibit ROS for tumor suppression, and a plethora of studies have demonstrated their application.^[51] Recently, nanocarrier loaded natural antioxidants, antioxidant enzymes or their mimics have attracted huge interest from investigators.

Natural antioxidants such as curcumin, resveratrol, polyphenols and flavonoids have been reported to counteract and neutralize ROS in the tumor or TME thereby inhibiting tumors.^[52] Nano-antioxidants, referring to encapsulations of antioxidants into nanocarriers, antioxidant-derived nanoparticles, can achieve safe and efficient delivery of a high payload of antioxidants for eradicating cancer. One phytosterol found in a variety of food-producing plants, such as natural oils, nuts, and soy products, is called sitosterol. It has been shown to have therapeutic potential for decreasing cholesterol and low-density lipoprotein, scavenging free radicals and preventing cancer. Sitosterol-derived nano-antioxidant therapy employing alginate/chitosa nanoparticles (sito-Alg/Ch/NPs) was described by Afzal et al.^[53] In vitro and in vivo results showed that these NPs exhibited higher cytotoxicity due to enhanced drug release patterns, improved bioavailability and antioxidant potential in breast cancer. Resveratrol, a type of polyphenol, is well-documented to function as an antioxidant for protecting the body from diseases including cancer. Increasingly studies have demonstrated that resveratrol inhibits cellular events associated with tumorigenesis and progression by inhibiting the activity of COX-1 and COX-2, impeding TPA-induced DNA binding of NF-kB.^[54] Shi et al. recently created resveratrol-loaded Zein-SHA (low-molecular-weight sodium hyaluronate) nanoparticles. According to increased ABTS free radical scavenging ability and iron (iii) reduction power, resveratrol in capsules has stronger antioxidant activity than free resveratrol. With IC₅₀ values of 14.73 and 17.84 g mL^–1, respectively, this nanosystem also demonstrated more antiproliferative activity than free resveratrol in 4T1 murine breast cancer cells.^[55] By encasing antioxidants in nanoparticles, researchers can increase the compounds’ bioavailability, biodistribution and capacity to target specific tissues or receptors, resulting in a regulated release of chemicals over an extended period of time.

Recently, the delivery of antioxidant enzymes or their mimics is emerging as a method of reducing oxidative stress for tumor suppression. Mainstream research has been devoted to efficiently delivering CAT and SOD among numerous enzymes to mitigate oxidative stress for therapeutic purposes because the activity of other enzymes requires many co-factors and/or secondary enzymes for proper function. CAT and its mimics have been widely utilized to convert H₂O₂ into O₂ by taking advantage of the high levels of H₂O₂ in TME or inside tumors as described above. Recently, Wu et al. introduced a competent nanoplatform (denoted CSI@Ex-A) fabricated by encapsulating catalase (CAT) into silica nanoparticles (CAT@SiO₂) and then loading them with sonosensitizer indocyanine green (ICG), and further coating with AS1411 aptamer-modified macrophage exosomes.^[56] In this approach, CAT@SiO₂ is dedicated to driving tumor hypoxia; the role of the macrophage exosomes is to cross the blood–brain barrier (BBB). After tumor cell endocytosis, this nanoplatform undergoes GSH triggered biodegradation and effective O₂ self-supply, thereby emerging as a promising therapeutic modality for glioblastoma (GBM). Additionally, a proliferation of nanomaterials with CAT mimicking action, such as metal–organic frameworks (MOFs), manganese dioxide (MnO₂) and cerium oxide (CeO₂) nanoparticles, has attracted significant interest in biological applications for the treatment of cancer.^[57] Recently, a CAT@Pt^IV-liposome system was designed by encapsulating catalase inside cisplatin(iv)-prodrug-conjugated phospholipid formed liposome nanoparticles. This system shows outstanding enzyme activity to trigger decomposition of H₂O₂ into O₂ for hypoxia relief. After X-ray radiation, treatment of CAT@Pt^IV-liposome induces significant DNA damage in cancer cells, with potential for clinical translation.^[58] Notably, studies were conducted to simultaneously encapsulate CAT and SOD in wind chime-like cyclodextrin (WCC) for efficient protein delivery.^[59] By simply mixing with protein solution to create SC/WCC, the amphiphilic WCC may self-assemble into nanoparticles in aqueous solution and provide better encapsulation of these two antioxidant enzymes. This nanoparticle can integrate the synergistic impact of SOD and CAT to increase the elimination of reactive oxygen species (ROS) thanks to the safe and effective transport provided by WCC nanovehicles.

Nanoparticle-mediated amplification of oxidative stress for cancer therapy

While modest levels of ROS activate multiple pro-tumor signaling pathways, excessive ROS exert cytotoxic effects by oxidizing biomolecules such as nucleic acids and lipids. Consistent with the notion that the ROS levels of tumor cells are elevated compared to their normal counterparts, tumor cells are more vulnerable than non-transformed cells to pharmacological treatments that induce excessive ROS accumulation. In fact, many organic and inorganic substances have the ability to cross the ROS threshold and activate multiple signaling pathways, such as p53, tumor necrosis factor (TNF)-signaling, extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase (MAPK), leading to oxidative damage and programmed cell death in a number of malignancies.^[60] Recent advances in nanotechnology provide novel and powerful tools to specifically target tumors and enhance the performance of active compounds. Various NPs, particularly metallic NPs, can directly interact with the cellular membranes, organelles or macromolecules to induce oxidative stress.^[61] In fact, a large body of research has shown that the toxicity of NPs is frequently linked to the creation of oxidative stress, which leads to genomic instability, protein malfunction and eventually deregulates enzyme activity, causing cellular dysfunction and cell death in cancer cells.^[62]

Metallic NPs have improved potential to take advantage of the oxidative radicals generated by the metals for selective destruction of diseased cells, thus emerging as valuable and efficient diagnostic and anticancer agents.^[63] Generally, metallic elements function as charged vehicles and generate soluble cations to form complexes with natural cellular components.^[64] Additionally, metal ions with a positive charge may regulate electron transport to help catalyze substrates and enzymes. According to certain studies, metallic nanoparticles can stimulate inflammatory cells like neutrophils and macrophages to produce more ROS. Certain metals, particularly transition metals, were discovered to promote the production of free radicals and lipid peroxidation (LPO). These metals include titanium dioxide (TiO₂), zinc oxide (ZnO), cerium oxide (CeO₂) and silver (Ag). For instance, it has been shown that ZnO NPs can produce excessive ROS production and activate mitochondrial-mediated apoptotic signaling, making them useful for anti-cancer research. The polymer-modified zinc peroxide nanoparticles (ZnO₂ NPs) that Lin et al. described are noteworthy because they combine endogenous and external ROS to intensify oxidative stress.^[65] ZnO₂ NPs underwent disintegration after being ingested by tumor cells, leading to the regulated release of H₂O₂ and Zn²⁺. Inhibiting the electron transport chain (ETC) could cause an increase in the production of mitochondrial O₂˙⁻ and H₂O₂ which would have an additive effect on the anticancer effects of exogenously produced H₂O₂. Due to their good chemical stability and strong redox potential, TiO₂ and ZnO-based oxides have been most frequently used. In terms of their cytotoxicity, the majority of TiO₂ and CeO₂ nanomaterials (NMs) were only marginally cytotoxic and had no long-term impact on the effectiveness of colony formation. However, ZnO and Ag NMs had an adverse effect on cell survival and produced significant DNA damage at cytotoxic levels.^[66] In a similar vein, another study found that TiO₂ nanoparticles at concentrations between 0.1 and 100 g mL^–1 did not appear to be toxic to peripheral blood mononuclear cells, whereas ZnO₂ nanoparticles caused severe damage at concentrations of 1 g mL^–1, inhibited the production of interleukin-1 and interleukin at 6.5 g mL^–1 and at higher concentrations promoted aggregation and degradation of malate dihydrogen.^[67]

Several nanosystem-based therapeutic strategies that can selectively kill cancer cells by ROS generation have aroused enormous attention due to their advantages such as an excellent safety profile, minimal toxicity and non-invasiveness.^[68] The most representative amongst them is photodynamic therapy (PDT), which employs a light excited photosensitizer (PS) to generate ROS in the presence of O₂ to selectively kill tumors.^[69] In this process, the PS converts from the ground state into a singlet-excited state, and then a triplet-excited state upon absorption of photons to generate ˙O²⁻ or ¹O₂ by undergoing electron transfer with biomolecules. Obviously, the supply of sufficient quantities and the capability of photosensitizers for ROS production are robust tools for the enhancement of the therapeutic efficacy of PDT. In this sense, the use of biocompatible metallic nanoparticles, AuNPs and AgNPs, is particularly exciting, and numerous studies have shown the successful use of PDT in a variety of cancers, including colorectal, lung, cervical, liver and GBM malignancies.^[70] For instance, a study by Dai et al. showed that g-C3N4 nanosheet coated with AuNPs could produce a lot of ROS when exposed to a 670 nm laser, considerably suppressing human non-small cell lung cancer, breast cancer and human cervical carcinoma both in vitro and in vivo.^[71] Indeed, PDT has been available for more than 40 years with multiple formulations, including AuNPs, having been investigated in clinical trials^[72] (NCT01679470, NCT00848042), and notably, several PSs, such as Photofrin, Foscan and Rada chlorin, have been used in the clinic.^[73]

Chemodynamic therapy (CDT) is an emerging strategy that produces toxic ˙OH independent of external light by undergoing a Fenton or Fenton-like reaction in the presence of excessive intracellular H₂O₂ in tumor tissues.^[74] As is well known, ˙OH possesses higher activity than ¹O₂, thus providing better tumor-killing ability. So far, multiple investigations have demonstrated the promising efficiency of CDT in multiple tumors.^[75] Recently, Zhang et al. summarized the development of CDT and their antitumor applications, with a critical discussion about the future development trend and challenges of CDT.^[76] Another emerging strategy is sonodynamic therapy (SDT), which utilizes ultrasound to activate agents for ROS generation, thus inducing apoptosis in cancer cells.^[77] For instance, by encapsulating the sonosensitizer chlorin e6 (Ce6) in the core and then conjugating anti-PD-L1 antibody (aPD-L1) to the interlayer, with a PEG coating, which could be sheddable at a low pH value (6.5) of the TME, Yang et al. created a lipid (LP)-based micellar nanomedicine.^[78] With only mild immune-related side effects, this approach enabled tumor-targeting administration that triggered anti-tumor immunity (irAEs). A SDT activated by ultrasonic insonation also generates tumor-killing ROS in conjunction with immunity, resulting in a potent anti-cancer immunity and long-term immunological memory to successfully inhibit melanoma. Overall, these novel therapies offer fresh ideas for creating integrated anticancer drugs based on NPs that target and eliminate cancerous cells by raising their ROS setpoint with little invasion.

Interestingly, several natural compounds have recently gained significant attention as anti-tumor medicines due to their capacity of eliciting oxidative stress.^[79] For instance, excessive doses of polyphenols can have pro-oxidant lethal effects by suppressing the Nrf2 pathway and antioxidative genes like GPX, heme oxygenase-1 (HO-1) and sirtuin-1 from being expressed (Sirt1). As a result, NP-based controlled drug delivery systems that are secure and appropriate have been utilized to assure effective administration of these therapeutic candidates into the tumor site. As an illustration, Shi et al. found that ZnO-PBA-Curcumin, a phenyl boronic acid (PBA)-conjugated and pH-responsive ZnO nanoparticles loaded with Curcumin (a polyphenol obtained from the herb Curcuma longa), can induce apoptotic cell death in MCF-7 human breast cancer cells by inducing oxidative stress and mitochondrial damage.^[80] Quercetin, a plant-derived bioflavonoid loaded into PBA-ZnO nanoparticles (referred to as PBA-ZnO-Q), caused apoptosis in MCF via enhancing oxidative stress and mitochondrial damage, as demonstrated by Sadhukhan et al.^[81] Together, these significant findings suggest that phytochemicals hold potential to eradicate cancer cells by ROS-induced cell death and apoptosis, the nanoparticles ensuring their efficient transport and high efficacy against tumors.