Introduction

Nonalcoholic fatty liver disease (NAFLD) is the hepatic manifestation of metabolic syndrome, encompassing a spectrum ranging from nonalcoholic fatty liver (NAFL) to nonalcoholic steatohepatitis (NASH). Amid the epidemic of obesity and diabetes, the global prevalence of NAFLD is estimated to be 25% and still rising.1,2 Furthermore, while NAFLD generally progresses slowly, 20% of patients experience accelerated disease progression, particularly in the fibrotic stage.1,2

At present, no specific agent has been approved for NAFLD, except for lifestyle modifications (exercise and dietary restrictions). Pharmacological therapy, such as lipid-lowering drugs (fibrates and statins), antihyperglycemic drugs (metformin), incretin hormone [glucagon-like peptide-1 (GLP-1) analogs], insulin sensitizers, and antioxidants (vitamin E), should only be prescribed to patients with multiple risk factors after a thorough assessment of the potential risks and benefits.3 In addition, several natural extracts, such as curcumin4 and resveratrol,5 have entered the spotlight due to the pharmacological properties. However, poor oral absorption, low water solubility, limited bioavailability, and uncertain efficacy of these drugs, significantly restrict their clinical application.6,7

Chronic hepatitis B virus (HBV) infection is another major etiology of chronic liver disease with 296 million existing infected individuals worldwide. Furthermore, although effective HBV vaccines are available, new infections still occur as limited access to prophylaxis objectively exists in some regions. Currently, the clinically available antiviral treatments include nucleos(t)ide analogues and pegylated-interferon α, but due to the inability of these drugs to fully eliminate the viruses, 20%‐30% of the patients still experience recurrent inflammation and progression to liver cirrhosis or hepatocellular carcinoma (HCC).8,9

In the past, NAFLD was strictly defined as occurring only in the absence of other factors, such as viral hepatitis, autoimmune diseases, or excessive alcohol intake.10 Recently, NAFLD has been redesignated as metabolic dysfunction-associated fatty liver disease (MAFLD), reflecting its metabolic origins rather than being an exclusive diagnosis.11,12 Therefore, it can coexist with conditions like chronic hepatitis B, which synergistically contribute to disease progression.13 Given the high prevalence of MAFLD and chronic HBV infection, it is imperative to investigate novel therapies that effectively target MAFLD and offer additional benefits for patients with concurrent chronic HBV infection.

Nanomaterials, which emerged in 1981, such as lipid-based nanoparticles, polymeric nanoparticles, inorganic nanoparticles, and nanogels, have found widespread application in medicine due to their ability to overcome the limitations of conventional drugs.14,15 These nanomaterials improve bioavailability,16–20 reduce side effects,21–25 and optimize the drug distribution across tissues7,21,23,26–30 by enhancing the stability of pharmaceuticals and enabling targeted delivery in NAFLD/MAFLD.

In this review, we will summarize potential therapeutic nanomaterials for MAFLD and chronic HBV infection, aiming to provide new insights into the treatment of patients with both conditions. For clarity, we will consistently refer to the disease as NAFLD throughout this paper, given the variation in definitions across studies.

Pathogenesis of NAFLD and Chronic HBV Infection

NAFL is the initial stage of NAFLD, characterized by the accumulation of lipid droplets in more than 5% of hepatocytes, with or without inflammation. NASH, a more aggressive form with a higher risk of progressing to end-stage liver disease, is defined by the coexistence of hepatic steatosis, lobular inflammation, and hepatocyte injury, with or without fibrosis. Recently, the “multiple-hit” hypothesis, which asserts that the synergistic interaction of multiple parallel factors leads to the development and progression of NAFLD in genetically predisposed individuals, has replaced the “two-hit” theory and gained widespread acceptance31 (Figure 1). Lipids accumulate in the liver in the form of triglycerides, accompanied by increased lipotoxicity due to elevated levels of free fatty acids and cholesterol, leading to mitochondrial dysfunction, reactive oxygen species (ROS) production, oxidative stress, and endoplasmic reticulum (ER) stress.31 Impaired autophagy induced by oxidative stress further exacerbates the accumulation of damaged organelles and lipids in hepatocytes.31 Insulin resistance increases hepatic de novo lipogenesis while inducing adipose tissue lipolysis and dysfunction, resulting in an elevated influx of free fatty acids to the liver and altering the production and secretion of adipokines and inflammatory cytokines.31 Additionally, altered gut microbiota further promotes the production of fatty acids in the intestines, increases small bowel permeability, and enhances fatty acid absorption, thereby triggering the release of proinflammatory cytokines and activating inflammatory pathways.31 These factors collectively contribute to chronic hepatic inflammation and injury, rather than acting through a simple, stepwise accumulation of insults over time.

Figure 1 The pathogenesis and representative therapeutic nanomaterials of NAFLD.

Note: Created in BioRender. Guixin, (L) (2025) https://BioRender.com/h50i906.

The pathogenesis of chronic HBV infection involves both direct viral effects and immune-mediated processes. On one hand, the expression and accumulation of viral proteins, resulting from HBV replication or integration, can lead to oxidative stress, mitochondrial dysfunction, and ER stress.32,33 On the other hand, the host’s prolonged immune response, particularly through cytotoxic T lymphocytes, initiates the recognition and clearance of HBV-infected hepatocytes.34 These two mechanisms synergize to exacerbate liver damage and accelerate fibrosis progression. Additionally, HBV integration into the host genome, or the interference of the HBx protein in cellular signaling pathways, DNA repair, and apoptosis, contributes to hepatocarcinogenesis, even in the absence of cirrhosis.35

Liver-Targeted Delivery Systems

For therapeutic nanomaterials, tissue-targeted delivery systems can significantly reduce toxicity and improve bioavailability. Currently, liver-targeted delivery systems are commonly used for the treatment of NAFLD and chronic HBV infection.36 The absence of a basement membrane and the presence of fenestrations in liver sinusoidal endothelial cells (LSECs) provide the physiological basis for the passive accumulation of nanomaterials in the liver. Besides, the mononuclear phagocyte system, including Kupffer cells, monocytes, and splenic macrophages, helps sequester the majority of nanomaterials in the liver.37 Phagocytosis by the mononuclear phagocyte system is influenced by the route of administration and the properties of nanomaterials, such as size, shape, charge, and rigidity. Nanomaterials ranging from 50 to 250 nm in size, with non-spherical shapes, high charge density, and surface hydrophobicity, are more likely to be captured by the hepatic mononuclear phagocyte system upon entering the bloodstream, thereby facilitating hepatic accumulation.37,38 This effect may result from opsonization, in which opsonins bind to the nanomaterials, enhancing their recognition and uptake by macrophages.38 Additionally, albumin-based formulations target the liver by leveraging the transcytosis of albumin through LSECs, facilitating precise delivery to the space of Disse.39 Moreover, long half-life, high stability, and capacity to bind hydrophobic molecules enhance albumin’s accumulation, making it an effective drug delivery vehicle for liver diseases.40

Several characteristics of the liver can be utilized for active liver-targeted strategies:36 (1) The larger pore size of LSECs compared to capillary walls in most tissues: Macromolecules can enter liver tissue and accumulate. For instance, the accumulation of dextran in the liver is tissue-dependent based on molecular weight. (2) Various major uptake transporters on hepatocyte membranes: The Na+-taurocholate co-transporting polypeptide, which is liver-specific and responsible for conjugated bile acid transport, serves as an effective mechanism for liver-targeted delivery. (3) Other receptors on hepatocytes, LSECs and Kupffer cells: The asialoglycoprotein receptor (ASGPR) on hepatocytes binds to sugars, enabling targeted delivery of nanomaterials conjugated to sugar chains, such as galactose (Gal), lactose, N-acetylgalactosamine (GalNAc), and asialofetuin. Moreover, glycyrrhizic acid binds to multiple sites on the hepatocyte membrane and can be used to enhance liver-targeting properties of nanomaterials. Active targeting strategies offer a more precise approach to liver-specific delivery by addressing some limitations of passive targeting, such as uneven drug distribution and the potential for non-specific uptake.

Notably, as liver fibrosis and HCC progress, the structural and microenvironmental changes in liver tissue, along with the unique characteristics of liver cancer cells, necessitate distinct liver-targeted delivery strategies. After the onset of liver fibrosis, the loss of fenestrations in LSECs as well as the microvilli in hepatocytes impair the delivery of blood-borne substances, which can be addressed by targeting activated hepatic stellate cells via specific receptors.36 In HCC, while carcinogenic transformation impairs the effective delivery of drugs, the enhanced permeability and retention effect of the highly vascular tumor environment can be leveraged for passive targeted delivery.36 Highly expressed antigens and enzymes can be utilized for HCC-targeted delivery, though their expression should be evaluated due to individual variations.41

Additionally, the characteristics, such as low pH and increased ROS, allow for the design of environment-responsive nanomaterials that are sensitive to pH or redox conditions.36 Furthermore, the complex interactions between the liver, gut and adipose tissue during the progression of liver diseases suggest that nanomaterials designed to target the gut and adipose tissue may exert indirect therapeutic effects on liver conditions.

Application of Nanomaterials in NAFLD Nanomaterials Loaded With Approved Drugs Hypolipidemic Drugs

Fenofibrate (FNB) is used clinically to treat dyslipidemia by acting as an agonist of peroxisome proliferator-activated receptor (PPAR) α, which enhances triglyceride hydrolysis and increases high-density lipoprotein synthesis.42 Beyond its lipid-lowering effects, FNB also impacts inflammation, oxidation, and apoptosis.42 Statins, including rosuvastatin, simvastatin and atorvastatin, are commonly used for lowering low-density lipoprotein-cholesterol (LDL-C) by inhibiting HMG-CoA reductase, the key enzyme in cholesterol biosynthesis.19 Furthermore, statins can enhance oxidase activity, reduce lipid peroxidation, protect liver endothelium, and even stabilize or reverse fibrosis by inhibiting HSC proliferation.43 However, these drugs suffer from inconsistent oral absorption, low solubility, and limited bioavailability, which hinder their clinical effectiveness.19,42,43

Nanoliposomes, bilayered spherical nanoparticles formed by phospholipids, are biodegradable and less toxic, protecting drugs from degradation and enabling sustained drug release in the gastrointestinal tract, thereby increasing plasma drug concentration.44 Moreover, water-based polyurethane nanoparticles can inhibit macrophage polarization to the M1 phenotype by reducing secretion of inflammatory cytokines.45 Previous studies demonstrated that both FNB-loaded nanoliposomes and polyurethane nanoparticles significantly enhanced the oral absorption of FNB and exhibited superior efficacy in inhibiting NAFLD compared to crude FNB.44,45 Furthermore, a recent study has revealed that FNB-loaded polymer-lipid hybrid nanoparticles, utilizing DSPE-PEG and ROS-responsive peroxalate ester derived from vitamin E (OVE), achieve higher drug-loading efficiency via π−π stacking interactions between FNB and OVE compared to other formulations like FNB nanoliposomes.42 FNB-loaded nanoparticles significantly reduced hepatic lipid accumulation by upregulating PPARα expression and suppressed oxidative stress via OVE’s synergistic antioxidant effect.42 Similarly, FNB and ketoprofen share benzophenone structures, facilitating π-π stacking interactions. A co-assembled nanosystem combining FNB with ketoprofen-GDFDFDY, which exhibited strong self-assembly properties and selectively inhibited cyclooxygenase-2, significantly improved hepatic lipid accumulation and inflammation, further emphasizing the promising potential of FNB-based nanoparticle systems in the treatment of NAFLD via a series of synergistic mechanisms.16

For statins, in an in vitro model, self-assembled rosuvastatin-loaded cell membrane-derived nanoparticles significantly reduced the accumulation of intracellular triglycerides and cholesterol.19 Likewise, simvastatin-loaded liposomal nanoparticles effectively reduced oxidative stress through the enhancement of the kruppel-like factor 2-nitric oxide signaling pathway, and also decreased pro-inflammatory cytokines and collagen I expression.43

Hypoglycemic Agents

Exenatide (EXE), a GLP-1 analog that enhances glucose-dependent insulin secretion and suppresses glucagon release, is now being widely studied in clinical trials for its potential to treat NAFLD.46 Besides the effects on glucose metabolism, EXE also influences lipid metabolism through the activation of sirtuin-1 (SIRT1).47 As reported, SIRT1 suppresses lipid synthesis, reduces oxidative stress, and promotes fatty acid β-oxidation through deacetylation of PPARγ as well as interaction with two other metabolic regulators: the farnesoid X receptor (FXR) and miR-34a.47 FXR agonists, like ursodeoxycholic acid (UDCA) and obeticholic acid (OCA), reduce steatosis, fibrosis, and inflammation by inhibiting lipogenesis and enhancing fatty acid β-oxidation.47 In contrast, miR-34a promotes the progression of NASH.47 Importantly, FXR activation not only suppresses miR-34a but also increases SIRT1 expression, which in turn further enhances FXR activity, creating a positive feedback loop that improves lipid metabolism and attenuates NASH progression.47

A previous study demonstrated that oral lipid nanocapsules loaded with EXE improved glucose homeostasis, showing greater effectiveness than subcutaneous injections.48 However, it did not completely resolve NASH in either high fat (HF) diet-fed foz/foz mice or western diet plus fructose-fed C57BL/6J mice.48 Chitosan is a natural, biocompatible, and biodegradable polysaccharide that regulates carbohydrate/lipid metabolism and improves insulin resistance. A novel UDCA-based oligochitosan derivative nanoparticle encapsulating EXE was developed for NAFLD treatment.47 This nanoparticle overcame the incompatibility between UDCA and EXE, enabled esterase-responsive release of drugs, and reduced lipid accumulation via the SIRT1 pathway.47 Likewise, UDCA-based oligochitosan derivative nanoparticles loaded with OCA and miR-34a antagomir also prevented NAFLD progression.49 To address the elevated LDL-C levels associated with OCA administration, carrier-free OCA-atorvastatin nanocrystals, formed through weak non-covalent interactions, were developed to enhance bioavailability, improve liver targeting, and effectively reverse NAFLD with fewer side effects.22

Nanomaterials Loaded With Natural Extracts Polyphenolic Compounds

Curcumin, a natural polyphenol from turmeric, has garnered attention for its antioxidant, anti-fibrotic, anti-inflammatory, and anti-lipidemic properties. In hamsters fed a high-fat, high-fructose diet and infected with Opisthorchis viverrini, curcumin-loaded nanocomplexes reduced hepatic steatosis and decreased the expression of genes linked to fatty acid uptake, inflammation, and fibrosis.50 Similarly, berberine, a natural alkaloid, showed the potential to slow NAFLD progression by improving insulin sensitivity, stabilizing LDL receptor mRNA, reducing oxidative stress, and modulating the AMP-activated protein kinase (AMPK) pathway. To overcome the poor oral bioavailability of both berberine and curcumin, diethylaminoethyl dextran, a cationic polymer, was applied to enhance nanoparticle stability and promote hepatocyte uptake via the ASGPR.6 Furthermore, clinical studies have demonstrated that curcumin-loaded nanoparticles improve glucose levels, lipid profiles, fatty liver, liver enzymes, and inflammatory markers in NAFLD patients.51,52

Another natural polyphenolic compound that has received widespread attention is resveratrol, known for reducing liver damage through its antioxidant and anti-inflammatory effects. NAFLD-targeted nanobubbles, modified with aptamers and loaded with resveratrol and ultra-small copper-based nanoparticles that possess enzymatic activity and ROS scavenging capabilities, demonstrated synergistic anti-inflammatory effects in vitro.26 Resveratrol-loaded polymeric nanoparticles also demonstrated enhanced efficacy in reducing lipogenesis and hepatocellular proliferation.53 α-Lipoic acid with disulfide bonds serves as a cross-linking agent in redox-responsive drug carriers. Lactobionic acid, containing Gal residues, targets hepatocytes by binding to the ASGPR. Glycogen-based nanoparticles, modified with α-lipoic acid and lactobionic acid to deliver resveratrol, effectively reduced lipid accumulation, oxidative stress and inflammation via the toll-like receptor 4 (TLR4)/ nuclear factor kappa B (NF-κB) pathway,28 while the Gal-modified oxidized starch lysozyme nanocarrier reduced lipid accumulation and improved insulin sensitivity via the AMPK/SIRT1/ fatty acid synthase (FASN)/ sterol regulatory element-binding protein-1c (SREBP-1c) pathway.7

In addition, it was demonstrated that hydroxytyrosol delivered via nanogels significantly reduced intracellular triglyceride accumulation.54 Exosome-like nanoparticles derived from blueberry rich in polyphenols enhanced insulin sensitivity, regulated detoxifying and antioxidant gene expression through nuclear factor erythroid 2-related factor 2 (NRF2) activation, improved liver function, reduced vacuole formation, and decreased lipid droplet accumulation.55

Flavonoid Compounds

A series of flavonoid compounds, including naringenin, vitexin, baicalin and silymarin, have been reported to exert anti-inflammatory, antioxidant, and anticancer effects, showing potential for treating NAFLD. Among these, pegylated vitexin-loaded nanoliposomes,56 as well as naringenin-loaded nanoliposomes57 and nanostructured lipid carriers17,58 further reduced hepatic triglycerides and enzymes in rats treated with CCl4 and urethane, or in methionine and choline deficient (MCD) diet-fed mice, respectively. Similarly, baicalin-loaded nanoliposomes mitigated lipid accumulation, hepatocyte apoptosis, fibrosis, and immune cell infiltration through the inhibition of TLR4 signaling and inflammatory mediator production.59 Furthermore, silymarin-loaded chitosan-modified lipid-polymer hybrid nanoparticles significantly enhanced therapeutic effectiveness in the livers of PNPLA3 I148M transgenic mice.18

Terpenoid Compounds

Celastrol and oridonin, both plant-derived terpenoids, exhibit potential in treating metabolic disorders. Celastrol enhances insulin sensitivity, upregulates antioxidant genes, and promotes anti-inflammatory macrophage polarization27 while oridonin possesses antioxidant, anti-inflammatory, and anti-fibrotic properties, along with the ability to maintain lipid and glucose homeostasis.60

Liver-targeted celastrol-loaded lactosylated albumin nanoparticles have shown superior performance in reducing body weight, improving insulin sensitivity, lowering cholesterol and triglyceride levels by downregulating lipogenesis genes and boosting lipolysis genes, which in turn mitigates liver fibrosis.27 Hexadecylphosphorylcholine can integrate into cell membranes, enhancing nanovesicle uptake and serving as a stable nanomaterial with high encapsulation efficiency. In addition, hydroxypropyl-β-cyclodextrin improves the solubility of hydrophobic compounds like oridonin. Accordingly, oridonin/hydroxypropyl-β-cyclodextrin/H9-hexadecylphosphorylcholine nanovesicles, designed to enhance stability and minimize leakage compared to traditional liposomes, showed efficacy in reducing hepatic steatosis and fibrosis in tetracycline-induced mice.60 The phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) pathway plays a critical role in metabolic disorders, oxidative stress, and inflammation. A ROS-scavenging nanomedicine co-delivering oridonin and LY294002, an inhibitor of the PI3K/AKT pathway, effectively alleviated NAFLD-induced systemic and hepatic oxidative stress, insulin resistance, inflammation, and fibrosis by modulating insulin-PI3K/AKT, transforming growth factor β and NF-κB pathways, demonstrating good biocompatibility.61

Others

Several natural compounds have shown therapeutic potential in NAFLD, particularly when delivered through nanoparticles to enhance bioavailability and targeting.

For instance, a combination of cordyceps extract and withaferin A, both known for their ability to reduce lipid accumulation, demonstrated enhanced lipid-lowering effects in vitro when delivered in oxygen nanobubble water.62 Nitidine chloride, an alkaloid with liver-protective, anti-inflammatory, and anti-cancer properties, was successfully delivered using chitosan-pectin nanoparticles.63 This nanosystem utilized ionic interactions between chitosan and pectin to form a polyelectrolyte complex at low pH, which slowed nitidine chloride release in the gastrointestinal tract, allowing it to reach the colon. There, the higher pH and gut microbiota degraded the chitosan and pectin, releasing the drug. This targeted release mechanism effectively reduced hyperlipidemia and liver damage by improving gut microbiota balance and lowering inflammatory cytokines.63 Similarly, nanocarriers delivering astaxanthin, a carotenoid from the lutein group known for its potent antioxidant properties, significantly enhanced insulin sensitivity, reduced hepatic fat accumulation, and effectively reversed NAFLD to a healthy state.64 In addition, a formulation combining the ginsenoside compound K with albumin improved ginsenoside compound K’s solubility and liver targeting, consequently slowing the progression of steatosis and fibrosis while also protecting cardiac tissues from lipotoxicity.65 Moreover, natural antibiotic extracts, platensimycin delivered in a liposomal formulation66 and rapamycin delivered via methoxy PEG- PLGA nanoparticles67 effectively reduced liver steatosis by modulating key metabolic genes, such as FASN, SREBP1c and PPARα, in western diet and CCl4-treated mice or HF diet-fed mice, respectively.

Nanomaterials Loaded With Chemically Synthesized Compounds

Some nanoparticles loaded with synthetic compounds exert the protective effects directly by modulating the lipid metabolism in NAFLD. Bilirubin acts as a hormone by binding directly to the nuclear receptor PPARα. Bilirubin nanoparticles enhanced the PPARα pathway, effectively lowering hepatic lipid accumulation and enzyme levels through boosting β-oxidation, regulating lipid transport, inhibiting lipid synthesis and decreasing ceramide production.68,69 Endocannabinoids are lipid ligands that bind to cannabinoid receptors CB1R and CB2R, promoting lipogenesis, insulin resistance and dyslipidemia. Rimonabant, the first compound targeting CB1R, was effective in delaying the progression of NAFLD but had neuropsychiatric side effects. To retain its metabolic benefits while minimizing risks, liver-targeted PLGA-encapsulated rimonabant nanoparticles were developed, showing potential in improving hepatic steatosis, liver injury, and insulin resistance.21 Additionally, BAM15, an oral mitochondrial uncoupler that enhanced lipid oxidation and reduced inflammation, was formulated into BAM15-albumin nanoparticles to improve low bioavailability and short half-life, effectively targeting the liver and reducing hepatic steatosis.23 Chitosan nanoparticles combined with nicotinamide reduced hepatotoxicity and improved insulin resistance, oxidative stress, and liver enzyme levels by restoring the homeostasis of nicotinamide adenine dinucleotide.25

Some nanoparticles regulate lipid metabolism in NAFLD by modulating the autophagy process. Nifedipine, a calcium channel blocker, prevented the accumulation of autophagy-related p62 and ubiquitinated proteins by restoring cytosolic calcium balance. Through this mechanism, intravenous administration of water-soluble nifedipine polymeric nanoparticles alleviated insulin resistance and reduced hepatic steatosis.70 Tat-Beclin, a peptide with a Tat cell-penetrating sequence and a segment from Beclin-1, promoted the release of Beclin-1 from the autophagy-inactive Golgi, enabling autophagosome formation. As a result, polymeric nanoparticle-formulated Tat-Beclin significantly reduced lipid droplet accumulation in vitro.30 Additionally, acid-activated nanoparticles restored lysosomal acidity, thereby reactivating autophagy and improving mitochondrial function, which ultimately reversed fasting-induced hyperglycemia and hepatic steatosis.71

Other nanoparticles play a role in the progression of NAFLD primarily by modulating inflammation. For example, dextran-based nanocarriers combined with dexamethasone shifted the pro-inflammatory phenotype of adipose tissue macrophages to the anti-inflammatory phenotype, improving liver inflammation and fibrosis.72 MCC950, an orally available NOD-like receptor protein 3 inflammasome inhibitor, was delivered via PEG-stabilized liposomes decorated with an anti-Frizzled-1 antibody, which targeted the plasma membrane receptor of inflammasome-activated THP-1 cells. This formulation effectively reduced inflammasome activation and liver inflammation, while slowing fibrosis progression.73

Nanomaterials Loaded With Gas Molecules

Gas molecules play important roles as signaling molecules, influencing various biological processes, including inflammation and oxidative stress. Gas-releasing nanomaterials offer a targeted and controlled release of these therapeutic gases, enhancing their bioavailability and reducing potential side effects. A previous study demonstrated that styrene maleic acid copolymer encapsulating carbon monoxide-releasing molecule exhibited enhanced bioavailability compared to natural carbon monoxide-releasing molecule.20 This nanoparticle effectively mitigated steatohepatitis and liver fibrosis by regulating carbon monoxide release and suppressing the inflammatory response.20 Additionally, hydrogen-rich water has been found to mildly reduce hepatic lipid accumulation in NAFLD patients. However, its delivery is limited, providing only about 19.4 mL of hydrogen gas per liter. Hydrogen nanocapsules by encapsulating ammonia borane into hollow mesoporous silica nanoparticles facilitated prolonged and high-dose hydrogen release in the gut, which effectively relieved metabolic disorders likely due to the reprogramming of lipid metabolism.74 Furthermore, N-(3-triethoxysilylpropyl) gluconamide modified magnesium silicide nanosheets, a novel hepatocyte-targeted hydrogen delivery system, enabled a localized, abundant, and sustained release of hydrogen directly into hepatocytes, suppressing hepatic inflammation and ferroptosis while improving liver metabolic function, achieving significant efficacy in preventing NAFLD.75

Nanomaterials Loaded With Nucleic Acids or Proteins

Nanomaterials can serve as delivery systems for therapeutic nucleic acids (eg, DNA, mRNA, small activating RNA, siRNA, or miRNA) or proteins, targeting hepatocytes to modulate key pathways involved in NAFLD progression, such as lipid metabolism, inflammation, autophagy, and mitochondrial function.

Interleukin-22 (IL-22) can improve glucose tolerance and insulin sensitivity while alleviating hepatic steatosis. When combined with apolipoprotein A1, which reduced hepatic steatosis, inflammation, and oxidative stress, IL-22 could be effectively delivered to the liver using self-assembling nanocarriers composed of chitosan, metformin, penetratin, and DSPE-PEG.29 This approach not only prolonged the half-life of IL-22 but also reduced off-target toxicity. In a similar vein, lipid nanoparticles were engineered to enhance gene delivery to the liver. For instance, replacing DSPC with POPC in lipid nanoparticles significantly improved the delivery of CTP cytidylyltransferase α mRNA, which promoted phosphatidylcholine synthesis, mitigating lipid accumulation, inflammation, oxidative stress, and fibrosis in NAFLD.76 Furthermore, the heparin-based polycationic vector was effective in delivering mammalian sterile 20-like kinase 1 mRNA to hepatocytes, where it activated the AMPK/SREBP-1c pathway, improving insulin sensitivity and reducing liver damage.77 Other polymeric nanocarriers, like 5-(G5)-triethanolamine-core polyamidoamine dendrimers loaded with small activating RNA targeting hepatocyte nuclear factor 4α, demonstrated the potential to improve lipid metabolism and regulate glucose homeostasis.78

As for siRNA, nanomaterials loaded with siRNA targeting the inositol-requiring enzyme 1α-X-box binding protein 1 (IRE1α-XBP1) pathway, which is critical for the unfolded protein response, reduced lipid accumulation and collagen deposition, as well as restored intestinal barrier integrity in NAFLD.79 Additionally, nanoparticles loaded with siRNA targeting methylation-controlled J protein, a mitochondrial inhibitor that restricts Complex I activity, improved mitochondrial function without increasing ROS levels, thereby reducing lipid accumulation and fibrosis.80 Furthermore, Rubicon, the interacting protein of Beclin-1 involved in the progression of NAFLD, could be targeted through hepatocyte-specific sgRubicon lipid nanoparticles, thus reducing hepatic steatosis.81 Moreover, nanoparticles loaded with siRNA targeting CD98, a key regulator of liver inflammation, effectively alleviated NAFLD.82 Methyltransferase-like 3 (METTL3), an m6A methyltransferase, has been implicated in immune evasion by decreasing CD8+ T cell infiltration in tumors through enhanced cholesterol biosynthesis. Correspondingly, siRNA targeting METTL3 delivered by nanoparticles activated cytotoxic CD8+ T cells, boosting anti-tumor immunity in NAFLD related HCC mouse model.83

For miRNA, targeted delivery of miR-146b mimic to hepatocytes by lactosylated PDMAEMA nanoparticles reduced proinflammatory cytokines as well as PPARγ, likely by degrading TLR4-related markers, consequently alleviating hepatic steatosis and inflammation.84 Additionally, metal-organic nanocarriers, composed of glycyrrhizic acid and zinc ions, were loaded with the circRNA_0001805 plasmid, and coated with a Gal-modified red blood cell membrane for targeted delivery.85 These nanocarriers overexpressed circRNA_0001805, which interacted with miR-106a-5p/miR-320a, restoring genes involved in lipid metabolism and inhibiting NF-κB signaling to protect against NAFLD.85

The HB-ATV-8 vaccine used a synthetic peptide in micellar nanoparticles to induce anti-cholesteryl-ester transfer protein antibodies, reducing plasma triglycerides and mitigating liver damage.86 Additionally, nanoparticles loaded with glial cell line-derived neurotrophic factor also protected against hepatic steatosis and liver fibrosis by downregulating PPAR-γ, PPAR-α, SREBP1 while activating the p38 mitogen-activated protein kinase (MAPK) signaling pathway.87

Other Forms of Nanomaterials

Nanoemulsions offer a promising approach to enhance the pharmacological efficacy of poorly soluble drugs by increasing the surface area for absorption and improving bioavailability through lipid content. Curcumin nanoemulsions,88 liver-targeted lovastatin nanoemulsomes designed with bile acid and fatty acids,89 and Vitamin D nanoemulsions90 demonstrated superior therapeutic effects over conventional forms in alleviating steatosis and inflammation.

Moreover, metal and metal oxide nanoparticles show potential in treating NAFLD through various mechanisms. As reported, zinc oxide nanoparticles protected against hepatic steatosis and insulin resistance via inhibition of SREBP-1c-mediated lipogenesis.91 Luteolin-conjugated zinc oxide nanoparticles,92 cerium dioxide nanoparticles24,93–99 and cerium/zinc nanocomposites100 exhibited enhanced antioxidant effects, improved insulin sensitivity, and reduced hyperlipidemia. Selenium nanoparticles101,102 alleviated lipid deposition, oxidative stress and liver injury by activating the PPARα and NRF2 pathways, while amorphous selenium nanodots103 mitigated liver inflammation and improved liver function via p38 MAPK signaling pathway.

Other innovative nanomaterials, such as surface-deacetylated chitin nanofibers, provided hepatoprotection by dual mechanisms of lipid adsorption and gut microbiota modulation, thus reducing oxidative stress and hepatic inflammation.104 Carbon quantum dots, including carbon quantum dots-lactoferrin complexes105 and Fe3+-chelating carbon dots,106 exhibited antioxidant effects that reduced liver fibrosis and managed iron-overload-induced liver conditions.

Overview of Therapeutic Nanomaterials in Chronic HBV Infection

The recurrence of chronic hepatitis B, even in “functionally cured” patients with negative HBsAg, is primarily due to the inability of current antiviral drugs to eliminate nuclear covalently closed circular DNA (cccDNA).107 Additionally, HBV DNA integrates into the host genome during replication, contributing to chronic infection and HCC.35 With the development of nanomaterial properties and optimization of fabrication techniques, nanomaterials may improve treatment outcomes and advance toward an HBV cure by drug delivery and gene editing.

Due to the small size and customizable surface properties, nanomaterials, such as polymer nanoparticles, lipid nanoparticles and metal nanoparticles, effectively delivered nucleos(t)ide analogues, improving bioavailability and therapeutic efficacy while reducing drug resistance and minimizing side effects.108–111 In particular, polymer nanoparticles could control drug release, extending therapeutic effects and reducing dosing frequency.108

Moreover, nanomaterials, including polymeric nanoparticles, lipid nanoparticles, conjugate nanoparticles and lipid-like nanoparticles, could carry engineered nucleases,112,113 siRNA114 or gene-editing tools, such as CRISPR-Cas9, enabling precise cleavage and deactivation of HBV DNA for effective viral inhibition or potential eradication.108 More importantly, nanomaterials not only improved delivery efficiency in gene therapy but also minimized off-target effects. As reported, ionizable lipidoid nanoparticles and advanced lyophilization technology could deliver siRNA targeting HBV, suppressing viral RNA, antigens and DNA.115 Apart from the common strategies for liver targeting, preS peptide-guided biomimetic nanoparticles also precisely delivered HBV siRNA to hepatocytes.116 Interestingly, recent studies have demonstrated novel biomimetic nanoparticles create stable and targeted CRISPR/Cas9 nanodrugs.117,118 By modifying the vehicle with red blood cell or hepatocyte membranes, these nanoparticles enabled efficient gene editing with immune evasion properties and enhanced clearance of cccDNA.117,118

Some nanovaccines focused on enhancing HBV-specific cellular and humoral immune responses, including mRNA encoding HBV antibodies,119 acting as adjuvants,120,121 and targeting molecules that regulate immune cell functions.122 Additionally, nanomaterials have been engineered for the codelivery of multiple therapeutic agents with different mechanisms of action, including siRNA for direct viral targeting and immune modulation.123

Discussion

For NAFLD or chronic HBV infection, ideal nanomaterials should possess high liver-targeting specificityto minimize off-target effects, strong biocompatibility to prevent immune responses, and controlled release capabilities to maintain consistent therapeutic levels and reduce dosing frequency. Efficient metabolism and clearance after treatment are also crucial to prevent long-term accumulation and potential toxicity.

The development of therapeutic nanomaterials for NAFLD concurrent with chronic HBV infection faces unique challenges, particularly due to the complex interplay between these two conditions.124 For instance, HBV activates mitophagy to clear damaged mitochondria, preventing host cell death and thereby facilitating viral replication.125 In contrast, NAFLD experiences impaired mitophagy, resulting in the accumulation of damaged mitochondria, which further exacerbates liver damage.125 This disparity in mitochondrial function hints that therapeutic approaches must carefully balance HBV persistence and NAFLD-induced cellular stress. Furthermore, it has been revealed that metabolic and immune alterations accompanying NAFLD progression can suppress HBV replication directly or stimulate antiviral immune responses indirectly.124 However, the heightened activity of immune cells can also aggravate hepatic inflammation and injury. Thus, it should be careful to modulate immune responses to avoid exacerbating liver damage in patients with coexisting conditions.

Altogether, managing NAFLD concurrent with chronic HBV infection requires addressing overlapping molecular and pathological mechanisms. It has been reported that HBx enhances the activity of liver X receptor on the SREBP-1c promoter, thereby upregulating the expression of SREBP-1c and its downstream lipogenic genes.126 Furthermore, HBx induces expression of PPARγ by increasing the level and activity of its activator, CCAAT/enhancer-binding protein α, which plays a crucial role in hepatic lipogenesis.126 Through the upregulation of these transcription factors and downstream lipid metabolism pathways, HBV facilitates its own replication and infectivity.126 These lipid synthesis regulators may serve as potential targets for therapeutic nanomaterials in the management of NAFLD coexisting with chronic HBV infection. Moreover, both NAFLD and chronic HBV infection lead to oxidative stress, a key pathogenic mechanism that induces hepatocyte damage, activates hepatic stellate cells, and accelerates fibrosis progression, potentially leading to HCC.127 Consequently, reducing non-specific hepatic inflammatory damage by targeting shared signaling pathways in NAFLD and chronic HBV infection, along with the use of anti-inflammatory drugs and antioxidants, may serve as potential strategies for therapeutic nanomaterials. Furthermore, a recent study demonstrated that in the NASH-HCC model, the residency and exhaustion of CD8+ T cell paradoxically contributed to HCC progression following the administration of immune checkpoint inhibitors.128 This finding highlights that early intervention with immunomodulatory nanomaterials may mitigate NAFLD-associated immune exhaustion and enhance HBV-specific antiviral responses.

Additionally, nanomaterials offer an opportunity for the co-delivery of multiple therapeutic agents targeting both the viral infection and the metabolic disturbances of NAFLD. A previous report indicated that an optimized lipid-like nanoparticle formulation enabled effective delivery of Cas9 mRNA and single-guide RNA to the liver, achieving in vivo targeting of both HBV DNA and the proprotein convertase subtilisin/kexin type 9 gene, an essential therapeutic target in hypercholesterolemia.129

Notably, the molecular interactions between NAFLD and chronic HBV infection remain incompletely elucidated, posing challenges for the precise design of nanomaterials. Moreover, chronic HBV infection exhibits distinct virological and immune features at different stages of the disease and across HBV genotypes. In the future, multi-omics approaches should be prioritized to identify key targets of NAFLD-HBV comorbidity and inform the functional modification of nanomaterials. Furthermore, the non-specific hepatic uptake of nanoparticles, particularly by Kupffer cells, and concerns about the long-term safety of nanomaterial degradation products, including potential hepatotoxicity and immunogenicity, hinder clinical translation. The application of biomimetic nanotechnology may facilitate immune evasion and enable targeted drug delivery. Thus, the development of more representative preclinical models that accurately mimic the coexistence of NAFLD and HBV infection is crucial for evaluating the therapeutic efficacy of nanomaterials, as most existing animal models focus on a single disease and have inherent flaws. For instance, NAFLD animal models vary in terms of modeling techniques and dietary formulations, only partially reflecting the characteristics of NAFLD patients. And simulating the chronic HBV infection state remains a challenge, especially in the presence of HBV-specific immune responses.130 In addition, from a pharmaceutical perspective, the complex synthesis of multifunctional nanomaterials and the high costs require careful assessments of the balance between therapeutic efficacy and economic feasibility.

Table 1 Characteristics of Nanomaterials for NAFLD Treatment

In summary, therapeutic nanomaterials hold significant promise in the management of NAFLD (Table 1), especially in patients with concurrent HBV infection, by enabling targeted drug delivery, modulating immune responses, and reducing hepatic inflammation, thus offering a potential approach for more effective, personalized treatments for patients with coexisting conditions.

Abbreviations

AKT, protein kinase B; AMPK, AMP-activated protein kinase; ASGPR, asialoglycoprotein receptor; cccDNA, covalently closed circular DNA; ER, endoplasmic reticulum; EXE, exenatide; FASN, fatty acid synthase; FNB, fenofibrate; FXR, farnesoid X receptor; Gal, galactose; GalNAc, N-acetylgalactosamine; GLP-1, glucagon-like peptide-1; HBV, hepatitis B virus; HCC, hepatocellular carcinoma; HF, high-fat; IL-22, interleukin-22; LDL-C, low-density lipoprotein -cholesterol; LSECs, liver sinusoidal endothelial cells; MAFLD, metabolic dysfunction-associated fatty liver disease; MAPK, mitogen-activated protein kinase; MCD, methionine and choline deficient; METTL3, methyltransferase-like 3; NAFL, nonalcoholic fatty liver; NAFLD, nonalcoholic fatty liver disease; NASH, nonalcoholic steatohepatitis; NF-κB, nuclear factor kappa B; NRF2, nuclear factor erythroid 2-related factor 2; OCA, obeticholic acid; OVE, peroxalate ester derived from vitamin E; PI3K, phosphoinositide 3-kinase; PPAR, peroxisome proliferator-activated receptor; ROS, reactive oxygen species; SIRT1, sirtuin-1; SREBP1c, sterol regulatory element-binding protein-1c; TLR4, toll-like receptor 4; UDCA, ursodeoxycholic acid.

Disclosure

The authors declare that there are no conflicts of interest in this work.

References

1. Younossi ZM. Non-alcoholic fatty liver disease - A global public health perspective. J Hepatol. 2019;70(3):531–544. doi:10.1016/j.jhep.2018.10.033

2. Younossi ZM, Koenig AB, Abdelatif D, et al. Global epidemiology of nonalcoholic fatty liver disease-Meta-analytic assessment of prevalence, incidence, and outcomes. Hepatology. 2016;64(1):73–84. doi:10.1002/hep.28431

3. Rinella ME, Sanyal AJ. Management of NAFLD: a stage-based approach. Nat Rev Gastroenterol Hepatol. 2016;13(4):196–205. doi:10.1038/nrgastro.2016.3

4. Mokgalaboni K, Ntamo Y, Ziqubu K, et al. Curcumin supplementation improves biomarkers of oxidative stress and inflammation in conditions of obesity, type 2 diabetes and NAFLD: updating the status of clinical evidence. Food Funct. 2021;12(24):12235–12249. doi:10.1039/D1FO02696H

5. Zeraattalab-Motlagh S, Jayedi A, Shab-Bidar S. The effects of resveratrol supplementation in patients with type 2 diabetes, metabolic syndrome, and nonalcoholic fatty liver disease: an umbrella review of meta-analyses of randomized controlled trials. Am J Clin Nutr. 2021;114(5):1675–1685. doi:10.1093/ajcn/nqab250

6. Chen Y, Jiang Z, Xu J, et al. Improving the ameliorative effects of berberine and curcumin combination via dextran-coated bilosomes on non-alcohol fatty liver disease in mice. J Nanobiotechnology. 2021;19(1):230. doi:10.1186/s12951-021-00979-1

7. Teng W, Zhao L, Yang S, et al. The hepatic-targeted, resveratrol loaded nanoparticles for relief of high fat diet-induced nonalcoholic fatty liver disease. J Control Release. 2019;307:139–149. doi:10.1016/j.jconrel.2019.06.023

8. Liang TJ, Block TM, McMahon BJ, et al. Present and future therapies of hepatitis B: from discovery to cure. Hepatology. 2015;62(6):1893–1908. doi:10.1002/hep.28025

9. Smolders EJ, Burger DM, Feld JJ, et al. Review article: clinical pharmacology of current and investigational hepatitis B virus therapies. Aliment Pharmacol Ther. 2020;51(2):231–243. doi:10.1111/apt.15581

10. Li G, Zhang J, Jiang Q, et al. CREBH knockout accelerates hepatic fibrosis in mouse models of diet-induced nonalcoholic fatty liver disease. Life Sci. 2020;254:117795. doi:10.1016/j.lfs.2020.117795

11. Eslam M, Sanyal AJ, George J, et al. MAFLD: a Consensus-Driven Proposed Nomenclature for Metabolic Associated Fatty Liver Disease. Gastroenterology. 2020;158(7):1999–2014e1991. doi:10.1053/j.gastro.2019.11.312

12. Eslam M, Newsome PN, Sarin SK, et al. A new definition for metabolic dysfunction-associated fatty liver disease: an international expert consensus statement. J Hepatol. 2020;73(1):202–209. doi:10.1016/j.jhep.2020.03.039

13. Lee YB, Ha Y, Chon YE, et al. Association between hepatic steatosis and the development of hepatocellular carcinoma in patients with chronic hepatitis B. Clin Mol Hepatol. 2019;25(1):52–64. doi:10.3350/cmh.2018.0040

14. Liu Y, Feng N. Nanocarriers for the delivery of active ingredients and fractions extracted from natural products used in traditional Chinese medicine (TCM). Adv Colloid Interface Sci. 2015;221:60–76. doi:10.1016/j.cis.2015.04.006

15. Wang X, Wang S, Zhang Y. Advance of the application of nano-controlled release system in ophthalmic drug delivery. Drug Deliv. 2016;23(8):2897–2901. doi:10.3109/10717544.2015.1116025

16. Wang Z, Ma C, Shang Y, et al. Simultaneous co-assembly of fenofibrate and ketoprofen peptide for the dual-targeted treatment of nonalcoholic fatty liver disease (NAFLD). Chem Commun. 2020;56(36):4922–4925. doi:10.1039/D0CC00513D

17. Hu R, Liu S, Anwaier G, et al. Formulation and intestinal absorption of naringenin loaded nanostructured lipid carrier and its inhibitory effects on nonalcoholic fatty liver disease. Nanomedicine. 2021;32:102310. doi:10.1016/j.nano.2020.102310

18. Liang J, Liu Y, Liu J, et al. Chitosan-functionalized lipid-polymer hybrid nanoparticles for oral delivery of silymarin and enhanced lipid-lowering effect in NAFLD. J Nanobiotechnology. 2018;16(1):64. doi:10.1186/s12951-018-0391-9

19. Zahid AA, Chakraborty A, Shamiya Y, et al. Cell Membrane-Derived Nanoparticles as Biomimetic Nanotherapeutics to Alleviate Fatty Liver Disease. ACS Appl Mater Interfaces. 2024;16(30):39117–39128. doi:10.1021/acsami.4c08240

20. Cui Y, Guo C, Xia Z, et al. Exploring the therapeutic potential of a nano micelle containing a carbon monoxide-releasing molecule for metabolic-associated fatty liver disease by modulating hypoxia-inducible factor-1α. Acta Biomater. 2023;169:500–516. doi:10.1016/j.actbio.2023.08.009

21. Hirsch S, Hinden L, Naim MB, et al. Hepatic targeting of the centrally active cannabinoid 1 receptor (CB(1)R) blocker rimonabant via PLGA nanoparticles for treating fatty liver disease and diabetes. J Control Release. 2023;353:254–269. doi:10.1016/j.jconrel.2022.11.040

22. Lu H, Ban Z, Xiao K, et al. Hepatic-Accumulated Obeticholic Acid and Atorvastatin Self-Assembled Nanocrystals Potentiate Ameliorative Effects in Treatment of Metabolic-Associated Fatty Liver Disease. Adv Sci. 2024;11(10):e2308866. doi:10.1002/advs.202308866

23. Jing W, Jiang M, Fu X, et al. Self-assembly drug-albumin nanocomposites for nonalcoholic fatty liver disease treatment. Int J Biol Macromol. 2022;214:697–707. doi:10.1016/j.ijbiomac.2022.06.167

24. Kobyliak N, Abenavoli L, Falalyeyeva T, et al. Prevention of NAFLD development in rats with obesity via the improvement of pro/antioxidant state by cerium dioxide nanoparticles. Clujul Med. 2016;89(2):229–235. doi:10.15386/cjmed-632

25. Abd-Allah H, Nasr M, Ahmed-Farid OAH, et al. Nicotinamide and ascorbic acid nanoparticles against the hepatic insult induced in rats by high fat high fructose diet: a comparative study. Life Sci. 2020;263:118540. doi:10.1016/j.lfs.2020.118540

26. Guo X, Huang Z, Chen J, et al. Synergistic delivery of resveratrol and ultrasmall copper-based nanoparticles by aptamer-functionalized ultrasound nanobubbles for the treatment of nonalcoholic fatty liver disease. Front Physiol. 2022;13:950141. doi:10.3389/fphys.2022.950141

27. Fan N, Zhao J, Zhao W, et al. Celastrol-loaded lactosylated albumin nanoparticles attenuate hepatic steatosis in non-alcoholic fatty liver disease. J Control Release. 2022;347:44–54. doi:10.1016/j.jconrel.2022.04.034

28. Li X, Chen XX, Xu Y, et al. Construction of Glycogen-Based Nanoparticles Loaded with Resveratrol for the Alleviation of High-Fat Diet-Induced Nonalcoholic Fatty Liver Disease. Biomacromolecules. 2022;23(1):409–423. doi:10.1021/acs.biomac.1c01360

29. Zai W, Chen W, Wu Z, et al. Targeted Interleukin-22 Gene Delivery in the Liver by Polymetformin and Penetratin-Based Hybrid Nanoparticles to Treat Nonalcoholic Fatty Liver Disease. ACS Appl Mater Interfaces. 2019;11(5):4842–4857. doi:10.1021/acsami.8b19717

30. Zagkou S, Marais V, Zeghoudi N, et al. Design and Evaluation of Autophagy-Inducing Particles for the Treatment of Abnormal Lipid Accumulation. Pharmaceutics. 2022;14(7):1379. doi:10.3390/pharmaceutics14071379

31. Buzzetti E, Pinzani M, Tsochatzis EA. The multiple-hit pathogenesis of non-alcoholic fatty liver disease (NAFLD). Metabolism. 2016;65(8):1038–1048. doi:10.1016/j.metabol.2015.12.012

32. Li G, Liu X, Lu F. What is the real sword of HBV precore and basal core promoter mutations piercing the hepatocyte homeostasis: hBcAg or HBsAg? J Med Virol. 2024;96(6):e29745. doi:10.1002/jmv.29745

33. Li G, Yang D, Liu X, et al. Precore mutation enhances viral replication to facilitate persistent infection especially in HBeAg-negative patients. Virol Sin. 2024;39(2):319–330. doi:10.1016/j.virs.2024.03.003

34. Bertoletti A, Ferrari C. Adaptive immunity in HBV infection. J Hepatol. 2016;64(1 Suppl):S71–S83. doi:10.1016/j.jhep.2016.01.026

35. Levrero M, Zucman-Rossi J. Mechanisms of HBV-induced hepatocellular carcinoma. J Hepatol. 2016;64(1 Suppl):S84–S101. doi:10.1016/j.jhep.2016.02.021

36. Chen J, Yao Y, Mao X, et al. Liver-targeted delivery based on prodrug: passive and active approaches. J Drug Target. 2024;32(10):1–14. doi:10.1080/1061186X.2024.2386416

37. Tang R, Li R, Li H, et al. Design of Hepatic Targeted Drug Delivery Systems for Natural Products: insights into Nomenclature Revision of Nonalcoholic Fatty Liver Disease. ACS Nano. 2021;15(11):17016–17046. doi:10.1021/acsnano.1c02158

38. Holgado MA, Martin-Banderas L, Alvarez-Fuentes J, et al.