Lipid nanoparticles (LNPs) are delivery vectors of nanoscale size, ranging from 80 to 200 nm, which are constructed using various biocompatible components, including lipids, phospholipids, cholesterol, and polyethylene glycol. LNPs share a similar molecular composition to the primary component of cell membranes, enabling good biocompatibility and nontoxicity in a physiological environment. In the past decade, LNPs have been developed as a nucleic acid delivery platform and achieved significant milestones in recent years, particularly in small interfering RNA (siRNA) and messenger RNA (mRNA) delivery. The rapid development of microfluidic technologies in recent years has also provided a new technical route for LNP production. Under the continuous production conditions, the microfluidic control of mixing behaviors in the solution can realize the highly reproducible generation of nanoparticles. For instance, with the platform integrated with staggered herringbone micromixers, the LNP size can be precisely controlled within the range of 20–140 nm by simply tuning the flow rate and solvent ratio, with a loading efficiency of up to 90%. In addition, the technology shortens the preparation steps from hours to minutes and reduces the production procedure to a single step.
LNPs have several competitive advantages in basic drug delivery tasks, as summarized in Table 1, and become one of the research hotspots of recent pharmaceutical studies. In addition, notable improvements have been made in the stability of LNPs. A novel class of cubic-phase lipid nanoparticles has been reported, which can retain the mRNA loaded in LNPs for up to three weeks at room temperature without significant degradation, which greatly shortens the storage and transportation process. In addition, a hybrid exosome system can be formed through fusion with natural exosomes, which keeps a high biocompatibility and significantly improves the delivery efficiency of macromolecules.
Table 1. Core Advantages of Lipid Nanoparticles in Drug Delivery.
| Advantage Category | Key Characteristics | Practical Value |
| Biocompatibility | Composed of natural membrane components such as phospholipids and cholesterol | Reduced immunogenicity; suitable for repeated administration |
| Drug Protection | Lipid bilayer structure encapsulates active molecules | Protects nucleic acids from enzymatic degradation; extends shelf life |
| Solubility Enhancement | Hydrophobic drugs solubilized in the lipid core | Improves bioavailability of poorly soluble compounds such as paclitaxel |
| Targeting Potential | Surface modification with targeting ligands | Enables organ-specific accumulation and reduces off-target distribution |
| Controlled Release | pH- or enzyme-responsive lipid designs | Enables triggered release in specific microenvironments |
| Payload Versatility | Compatible with both hydrophilic and hydrophobic agents | Supports combination delivery strategies |
LNPs can be formed by multiple physicochemical encapsulation mechanisms. For the negatively charged nucleic acids, ionizable cationic lipids do not carry a charge at physiological pH, thus reducing the interaction with blood components while enabling the electrostatic binding of nucleic acids during the preparation. With endosomal uptake, the protonation of the cationic lipids under the acidic microenvironment can promote the release of the payload. In contrast, the loading of hydrophobic small-molecule drugs into LNPs is mainly achieved by solubilizing the drug in the lipid phase. In the microfluidic system, the mixing of lipid solutions in ethanol solvent with an aqueous-phase leads to the instantaneous generation of lipid nanoparticles with a narrow size distribution. The microfluidic preparation method can produce much smaller nanoparticles compared to the thin-film hydration method. As a result, the former has been reported to have an encapsulation efficiency of up to 90% for atenolol and 88% for quinine, while conventional methods have only reached about 50%. In addition, continuous microfluidic synthesis of LNPs can improve the reproducibility and scalability of the synthesis process. The multilayer structures of LNPs also help improve their stability. The incorporation of cholesterol into LNPs can increase the rigidity of the lipid bilayer, reducing the probability of leakage in the circulatory system. In addition, the surface decoration of LNPs with polyethylene glycol forms a hydrated layer that can repel protein adsorption, thereby prolonging circulation time. A newly developed fusogenic LNP reported in 2023 can maintain structural stability for more than 20 days at room temperature and provides a potential alternative to cold-chain-dependent nucleic acid vaccines.
Cellular uptake of LNPs is primarily achieved through endocytosis, which is a process governed by the surface properties of the LNP. For example, in the delivery to liver cells, particle size and surface properties can be modified to allow adsorption of apolipoprotein E, a ligand of the low-density lipoprotein receptor expressed on the surface of hepatocytes. This approach has been used to drive the development of siRNA delivery platforms for the liver. The endocytosis of LNPs can be broadly divided into clathrin-mediated and caveolin-mediated pathways. Clathrin-mediated endocytosis is the most common pathway, which is the endocytosis process of nanoparticles by forming vesicles from the cell membrane. In contrast, caveolin-mediated endocytosis bypasses lysosomal degradation and directly transports the cargo to the endoplasmic reticulum. The internalization efficiency of nanoparticles is also related to their size, surface charge, and the type of target cells, with smaller size and a moderate positive surface charge generally facilitating endocytosis and excessive positive surface charges increasing toxicity. The hybrid exosome system can show a significantly higher uptake rate in cells. By fusing the drug-loaded cubic-phase LNPs with the natural exosomes, the endocytosis of such a system can be realized through exosomal membrane proteins on the cell surface. For example, in blood–brain barrier (BBB) models, this hybrid system can increase the permeability of immunoglobulin G (IgG) and mRNA approximately twofold, which demonstrates the advantage of exosomes in translocating through a complex biological barrier.
Endosomal escape is an important step that affects the efficiency of LNP delivery. Ionizable lipids in LNPs can be protonated in the acidic environment of the endosome and acquire positive charges, with which they can interact with the negatively charged phospholipids in the endosomal membrane, thus destabilizing the endosome. As the released charged lipid molecules insert into the endosome membrane, it will also induce a redistribution of charge within the membrane that contributes to its destabilization, leading to a process known as the proton sponge effect. The controlled release of cargo molecules from LNPs is also achieved through various routes. pH-responsive lipids have been reported to undergo a structural transition under mildly acidic conditions, promoting the release of the drug from LNPs. Thermosensitive lipids, on the other hand, can be designed for controlled release in response to local heating, which is suitable for drug delivery combined with thermal stimulation strategies. In addition, enzyme-responsive approaches have also been explored to improve the specificity of LNPs. In these systems, overexpressed enzymes in the target tissue can trigger the degradation of lipids and promote the release of drugs. For example, matrix metalloproteinase-responsive LNPs can achieve a selective release of encapsulated drugs in the microenvironment. In one study, the solid lipid nanoparticles carrying talazoparib showed a controllable release profile to overcome the resistance mechanism in triple-negative breast cancer and thus significantly improve the therapeutic performance of the drug. In another study, magnetic solid lipid nanoparticles were designed for spatially and temporally controlled drug release by an externally applied magnetic field and local heating, which were used for the controlled delivery of paclitaxel.
Active and passive delivery are two strategies for LNP targeting. The passive delivery of LNPs to solid tumors can be achieved through the enhanced permeability and retention effect. Nanoparticles with a size of around 100 nm can thus accumulate in tumors through the abnormal blood vessels of solid tumors. The targeting of specific organs or cells through the active strategy can be achieved by modifying the lipid composition of LNPs, which can affect their distribution in vivo. For instance, substituting helper lipids in LNPs, such as dioleoyl phosphatidylethanolamine, with cationic or anionic lipids can alter the organ distribution from liver accumulation to the spleen or lungs, respectively. Studies have demonstrated the successful reprogramming of lipid nanoparticles from hepatocellular to splenic or pulmonary targeting through rational lipid modifications, which provides new strategies for organ-specific delivery. Another commonly used active targeting approach is antibody conjugation. The conjugation of antibodies with the ability to recognize cell-surface antigens can significantly improve the efficiency of targeted delivery. Antibody-modified LNPs for the delivery of CRISPR-Cas components have been used to enable the selective delivery of gene-editing tools to target tissues while reducing the exposure of nontarget tissues. For instance, LNPs loaded with siRNA targeting long noncoding RNA have been used to effectively downregulate the expression of the target gene in acute myeloid leukemia cells. The BBB is a major barrier for the drug delivery to the central nervous system. In one study, a hybrid exosome system was shown to possess an excellent translocation ability. In this system, drugs were encapsulated in cubic-phase LNPs and fused with exosomes to achieve efficient BBB delivery of large biomolecules such as IgG and mRNA. As observed by confocal microscopy, this exosome hybrid system could successfully deliver labeled mRNA into the brain with no evidence of degradation, which opens a new delivery avenue for neurological diseases.
BOC Sciences provides versatile lipid nanoparticles with tunable compositions and functional modifications, offering customized solutions to enhance therapeutic delivery performance.
The unique pathological features of tumor tissue endow lipid nanoparticles with natural targeting ability. The vasculature of solid tumors is abnormal, and its structure has large gaps of 100–800 nm between the endothelial cells. The LNPs with an average size of 100 nm can pass through and accumulate in the tumor interstitium through enhanced permeability and retention. In addition, the lymphatic drainage of tumor tissue is weak, which prolongs the retention time of nanoparticles in tumor tissue and causes local enrichment of drugs. The emergence of multidrug resistance of tumor cells has led to the design of many functional LNPs. For example, the resistance of tumor cells to traditional chemotherapeutic drugs in triple-negative breast cancer is mainly due to the overactivation of the homologous recombination repair pathway. The encapsulation of talazoparib in the solid lipid nanoparticles enables a sustained release of the drug, and the continuous drug exposure in cells can effectively reverse the resistance. In animal models, talazoparib-loaded solid lipid nanoparticles had more than 40% improvement in tumor growth inhibition efficacy. Active targeting of LNPs can also be performed by coupling antibodies that bind tumor-specific antigens on the LNP surface, allowing specific recognition. In the treatment of acute myeloid leukemia, antibody-modified LNPs carrying small interfering RNA (siRNA) against the long noncoding RNA UCA1 can successfully downregulate its expression in leukemic cells and reverse chemosensitivity. Combinatorial delivery can also exhibit good synergistic effect. Multiple therapeutic agents, such as chemotherapeutic drugs and gene therapy, can be loaded in the same LNP for co-delivery, which can simultaneously exert inhibitory effects on different therapeutic targets. For example, the co-delivery of paclitaxel and siRNA targeting the resistance gene in LNPs not only overcomes drug resistance but also directly inhibits tumor cell proliferation, which is more effective than the single agent. Magnetic solid lipid nanoparticles can also be used for magnetic targeting in tumor treatment. A local magnetic field can be applied to the tumor site so that the nanoparticles can be aggregated at the site to achieve targeted accumulation. Local heating can also be used to release the drug to achieve temporal and spatial control.
Fig.1 LNP technology applications: vaccines, cancer, and gene therapy (BOC Sciences Original).
Table 2. Representative Applications of Lipid Nanoparticles in Tumor Therapy.
| Tumor Type | Delivered Cargo | Targeting Strategy | Key Technical Features |
| Triple-negative breast cancer | Talazoparib | Passive targeting | Solid lipid core enables controlled release and resistance modulation |
| Acute myeloid leukemia | Anti-UCA1 siRNA | Antibody modification | Targeting long noncoding RNA to restore drug sensitivity |
| Solid tumors (general) | Paclitaxel + resistance-related siRNA | Co-delivery | Multi-target intervention with synergistic effects |
| Glioma | Temozolomide | Transferrin modification | Enhanced blood–brain barrier penetration |
| Hepatocellular carcinoma | Sorafenib | Galactosylation | Recognition of hepatocyte surface receptors |
Drug delivery for cardiovascular diseases also requires selective accumulation of drugs at the vascular lesion site. In atherosclerotic plaques, LNPs carrying anti-inflammatory drugs can deliver the drugs across the fibrous cap and deposit them in the plaque core because of the inflammatory response. Simvastatin-loaded solid lipid nanoparticles can improve the aqueous solubility of the drug and target macrophages by optimizing particle size and significantly reduce the production of inflammatory factors in atherosclerotic plaques. Heart tissue repair after myocardial infarction also needs precise regulation of angiogenesis and fibrosis. After myocardial infarction, LNPs can be loaded with vascular growth factors for sustained release at the site of the infarct to promote neovascularization and improve tissue perfusion. Injectable hydrogels prepared from LNPs have been shown to increase new blood vessel density by 2.5 times in 4 weeks and significantly improve heart function. In addition, vascular restenosis is also a common problem after various interventional treatments. The LNPs loaded with the antiproliferative drug sirolimus can be delivered to the angioplasty site to inhibit the proliferation of vascular smooth muscle cells. Compared to the traditional drug-eluting stent, the LNPs in the injectable form can be directly injected into the lesion, and the release time can be prolonged for more than 30 days to achieve a good inhibitory effect.
The blood–brain barrier (BBB) is the main physical barrier that prevents most large molecules from entering the brain. The surface of LNPs can be modified with special ligands to carry out receptor-mediated transcytosis transport. The transferrin receptor (TfR) on the BBB is highly expressed, and the LNPs modified with transferrin or TfR antibody can significantly enhance drug accumulation in the brain. For the delivery of drugs to treat neurodegenerative diseases such as Alzheimer's disease, the brain is also the main target organ. Encapsulating anti-amyloid-β antibodies in LNPs with polyethylene glycol has been shown to be effective in plaque clearance. A recent study loaded brain-derived neurotrophic factor in LNPs modified with RVG peptide, which effectively improved cognition and increased hippocampal neuron survival by 35%. Parkinson's disease is caused by the loss of dopaminergic neurons in the substantia nigra region of the brain. Modified LNPs can target glial cell line–derived neurotrophic factor to the brain to protect the remaining dopaminergic neurons and enhance functional recovery. The delivery route of LNPs is mainly intranasal delivery, which can be directly delivered through the olfactory pathway to bypass the BBB and reduce systemic exposure. In preclinical studies, the drug concentration in the striatum reached up to 8 times higher than intravenous injection. In recent years, the combination of LNPs and natural exosomes to prepare hybrid exosome systems has been a major development in drug delivery to the CNS. Messenger RNA and other biomacromolecules can be encapsulated in LNPs with a cubic phase to form hybrid exosomes, which effectively combine the high-loading capacity of LNPs and the endogenous targeting ability of exosomes. Using in vitro BBB models, the permeability of immunoglobulin G and messenger RNA was doubled, with maintained structural integrity. Confocal laser scanning microscopy showed the successful uptake of messenger RNA by brain tissue and the potential it provides for research into the delivery of macromolecular drugs to the central nervous system.
Table 3. Lipid Nanoparticle Strategies for Central Nervous System Applications.
| Disease Type | Delivered Molecule | Barrier-Crossing Strategy | Delivery Outcome |
| Alzheimer's disease | Anti-amyloid-β antibodies | Transferrin receptor-mediated transport | Plaque reduction and cognitive improvement |
| Parkinson's disease | Neurotrophic factors | RVG peptide modification | Neuronal protection and functional recovery |
| Glioma | Temozolomide + resistance-related siRNA | Lactoferrin modification | Enhanced intracranial drug accumulation |
| Cerebral ischemia | Neurotrophic factors | Intranasal delivery | Rapid lesion targeting via BBB bypass |
| Platform approach | Messenger RNA | Hybrid exosome system | Twofold increase in BBB transport efficiency |
Messenger RNA delivery is one of the most mature application fields of LNP. Messenger RNA coding for functional proteins can be loaded in LNPs, translated after delivery into cells, and produced functional proteins. Microfluidic preparation technology can achieve rapid mixing of aqueous-phase mRNA solution and lipid-containing organic phase, and the resulting LNPs have high uniformity, and the encapsulation efficiency can reach more than 90%. The development of lyophilized formulation technology has also realized the storage of LNPs for several months at refrigerated temperatures, which has greatly improved the feasibility of storage and distribution. Small interfering RNA (siRNA) delivery can be used to regulate protein expression levels. The gene silencing process mediated by LNPs loaded with siRNA is that the LNPs can protect siRNA from degradation in the body and can enter the cytoplasm through endocytosis and then combine with the intracellular silencing complex to degrade the target messenger RNA. In viral replication and metabolic diseases, LNPs loaded with siRNA achieved long-term suppression of the target protein, which showed a strong effect. The direct delivery of proteins can avoid the uncertainties introduced by intracellular translation processes. Encapsulation of therapeutic proteins within the solid lipid nanoparticles protects the proteins from enzymatic degradation and prolongs their circulation time in vivo. For example, insulin-loaded LNPs modified with a peptide can be used for oral administration, which achieves good glycemic control in animal experiments. The delivery of antioxidant enzymes using LNPs modified with polyethylene glycol has also significantly improved the stability of proteins and targeting ability. Hybrid exosome–lipid nanoparticle platforms for gene and protein delivery also show great advantages. The hybrid platforms with the membrane components of natural exosomes incorporated onto the surface of LNPs have both the high loading capacity of LNPs and the endogenous targeting properties of exosomes. In the transport study of the BBB, the drug delivery efficiency of macromolecular cargos was doubled and the biological activity was maintained. This research platform provides a powerful drug delivery solution for the study of neurological diseases and the delivery of protein replacement therapy.
Table 4. Lipid Nanoparticle Technologies for Gene and Protein Delivery.
| Cargo Type | Representative Application | Key Technical Advances | Delivery Performance |
| Messenger RNA | Vaccine development | Ionizable lipids + microfluidic fabrication | >90% encapsulation, refrigerated stability for months |
| siRNA | Viral suppression | Enzymatic protection + endosomal escape | >99% target suppression with sustained effects |
| Proteins | Oral insulin delivery | Cell-penetrating peptides + solid lipid core | Improved bioavailability and functional control |
| Mixed macromolecules | Neurological research | Cubic-phase LNP–exosome hybrids | Twofold increase in BBB transport with intact payloads |
Ionizable lipids are key components of LNPs. Ionizable lipids are neutrally charged at the pH of the bloodstream to avoid undesirable electrostatic interactions with plasma proteins and to limit cytotoxicity. Ionizable lipids become protonated, and thus acquire a positive charge, in the acidic pH of the endosome. The incorporation of a positive charge into the ionizable lipid head groups is used to destabilize the endosomal membrane and promote payload release. Ionizable lipids such as ALC-0315 and SM-102 are now broadly used in the delivery of mRNA, as they have a near-zero net charge at pH 7.4 and a substantially increased charge at pH 5.5, and thus can mediate efficient endosomal escape. Optimizing helper lipids can also improve stability and overall performance. Neutral helper lipids, such as distearoyl phosphatidylcholine, pack into the lipid bilayer and help to fill empty space. Increasing the concentration of distearoyl phosphatidylcholine from 20% to 40% can increase serum stability by 3-fold and result in a circulation time of over 12 hours. Cone-shaped phospholipids, such as dioleoyl phosphatidylethanolamine, promote endosomal release by inducing membrane fusion between LNPs and endosomes. Modulating the content of PEG–lipid provides a balance between particle stealth properties and cellular uptake. PEGs with a molecular weight between 500 and 2000 Da have been shown to mask surface charge and provide protection from the RES. An increase in the density of PEG on the LNP surface may reduce recognition and internalization by cells. Optimal PEG-lipid content is between 1.5 and 2.5% of total lipids. This PEG-lipid content results in a prolonged circulation time and does not significantly impact uptake. Cleavable PEG-lipids have been designed to remain intact on the particle surface during circulation and to cleave upon encountering specific microenvironments, thus uncovering the particle surface and facilitating cell interactions. Cholesterol and cholesterol derivatives have also been used to improve membrane fluidity and structural integrity. Natural cholesterol is metabolized in the body relatively quickly and is used to modulate bilayer fluidity and membrane permeability. Plant sterols, such as β-sitosterol and stigmasterol, have higher chemical stability and enhanced binding to certain cell membranes. In studies of ocular delivery, LNPs with stigmasterol had approximately 60% higher uptake by retinal pigment epithelial cells than cholesterol-based LNPs.
Table 5. Representative Lipid Nanoparticle Formulation Platforms.
| Product | Description | Price |
| Ionizable Lipid–Based LNPs | Lipid nanoparticles using ionizable lipids that enable efficient nucleic acid encapsulation and intracellular release while maintaining near-neutral charge and favorable stability during circulation. | Inquiry |
| mRNA Delivery LNPs | Lipid nanoparticle formulations optimized for messenger RNA loading, providing high encapsulation efficiency, uniform particle size, and compatibility with scalable microfluidic preparation processes. | Inquiry |
| siRNA Delivery LNPs | Specialized lipid nanoparticles designed to protect siRNA and support effective cytoplasmic delivery, enabling reliable gene silencing with controlled size distribution and formulation reproducibility. | Inquiry |
| Solid Lipid Nanoparticles (SLN) | Lipid nanoparticles with a solid lipid core that enhance stability and controlled release of hydrophobic small molecules for sustained and reproducible delivery performance. | Inquiry |
| Cubic-Phase Lipid Nanoparticles | Non-lamellar lipid nanoparticles with cubic internal structures that support high macromolecule loading, improved physical stability, and extended storage under non-frozen conditions. | Inquiry |
| Targeted Lipid Nanoparticles | Surface-modified lipid nanoparticles functionalized with antibodies, peptides, or ligands to improve cellular recognition and enhance localization efficiency in targeted delivery applications. | Inquiry |
| PEGylated Lipid Nanoparticles | Lipid nanoparticles incorporating polyethylene glycol to reduce nonspecific interactions, extend circulation time, and balance stability with effective cellular uptake. | Inquiry |
| Hybrid Exosome–LNP Systems | Hybrid delivery systems combining lipid nanoparticles with exosomal membranes to improve biological compatibility and enhance transport efficiency across complex biological barriers. | Inquiry |
The most common approach to active targeting involves the conjugation of targeting ligands. Antibody fragments that bind to cell-surface antigens have been conjugated to the termini of PEG chains to direct LNPs to target cells. For instance, LNPs that have been modified with anti-HER2 single-chain antibodies exhibited >4-fold greater accumulation in HER2-overexpressing models in comparison with non-targeted formulations. Small-molecule ligands like folic acid target overexpressed folate receptors to generate significantly higher tissue concentrations of the delivered cargo. Peptide ligands are also frequently used due to their low molecular weight and low immunogenicity. For example, the transferrin receptor–binding T7 peptide, when conjugated to LNPs, conferred a ~3-fold improvement in brain accumulation due to increased transport across the blood–brain barrier. Arginine–glycine–aspartic acid (RGD) peptides target integrin receptors and direct LNP delivery to ischemic regions of the myocardium in applications of vascular regeneration. Neuronal receptor-specific peptides based on rabies virus glycoprotein have also been used to more than 5-fold increase the neuronal uptake efficiency. Glycosylation involves conjugation with carbohydrates for recognition via carbohydrate–lectin interactions. Galactose-conjugated LNPs bind to the asialoglycoprotein receptors on hepatocytes, enabling liver-specific targeting. Mannose-conjugated LNPs can also be used to target macrophages and dendritic cells via mannose receptors, which can significantly improve the efficiency of antigen presentation in vaccine delivery applications. Cell-penetrating peptides (CPPs) have been used to address a major drawback in cell uptake. Large cargos, such as plasmid DNA, can be directly delivered into the cytoplasm of cells through cell-penetrating peptides like TAT. Covalent conjugation of TAT to the LNP surface was shown to increase cellular uptake by up to 100-fold. Penetratin and oligoarginine peptides have also been used to 20- to 50-fold increase cellular uptake of LNPs in a range of cell types. Engineering LNPs using hybrid exosome systems is a relatively novel approach for surface modification. Preformed cubic-phase LNPs have been fused with naturally occurring exosomes using freeze–thaw or extrusion methods, to produce hybrid exosome systems that contain both LNPs and exosomes. In models of organ injury, the hybrid system showed preferential targeting to injured tissue, and a higher delivery efficiency compared with either the LNP or the exosome alone, providing a biomimetic platform to target organs that are difficult to access with traditional formulations.
Table 6. Surface Modification Strategies and Targeting Performance of Lipid Nanoparticles.
| Modification Type | Targeting Ligand | Recognized Receptor | Increase in Targeting Efficiency | Application Area |
| Antibody fragment | Anti-HER2 scFv | HER2 receptor | 4.2× | HER2-positive breast models |
| Small molecule | Folic acid | Folate receptor | 8.5× | Ovarian cancer models |
| Peptide | T7 peptide | Transferrin receptor | 3× | Neurodegenerative research |
| Peptide | RVG peptide | Nicotinic acetylcholine receptor | 5× | Neurological delivery |
| Glycosylation | Galactose | Asialoglycoprotein receptor | 3× | Liver-targeted delivery |
| Glycosylation | Mannose | Mannose receptor | 10× | Vaccine delivery |
| Cell-penetrating peptide | TAT | Direct penetration | 20–50× | Uptake enhancement |
Particle size is a critical factor that determines in vivo behavior of the particles. Nanoparticles less than 50 nm are cleared quickly from the blood circulation by renal filtration while particles larger than 200 nm are rapidly taken up by the reticuloendothelial system. 80–150 nm size range allows a compromise between these two extremes as the particles can accumulate in the tissue while remaining long enough in circulation. Microfluidic synthesis of LNPs provides very tight control over size distributions with standard deviations below 10 nm. The surface charge is another important property that can be tuned to maximize circulation half-life and uptake. Strongly positively charged nanoparticles interact more readily with cell membranes but tend to be more toxic and attract more proteins to their surface. Particles with neutral or weakly negative surface charge are more stable in circulation but tend to have reduced uptake. Ionizable lipids allow an additional level of control over surface charge properties. At neutral physiological pH ionizable lipids are close to neutral in charge while they become positively charged in acidic environments. Nanoparticles with ζ-potential in the range of –5 to +5 mV at pH 6.5–7.0 have been shown to exhibit a good balance between prolonged circulation and adequate cellular uptake. Optimal lipid composition ratios control structural properties and overall performance. Ionizable lipids usually make up for 30–50% of total lipid content to allow efficient encapsulation of nucleic acids and their subsequent release from the endosomes. The proportion of helper lipids is usually between 20 and 40% as they help form stable bilayers. Cholesterol is usually added to the LNPs in the 35–45% range to control membrane fluidity. PEG-lipid is usually 1.5–2.5% which is considered a good trade-off between stealth properties and cellular uptake. For example, in a siRNA delivery study, the ionizable lipid concentration in LNPs was increased from 20% to 40%. This change led to an increase in gene silencing efficiency from 45% to 85% with high cell viability. The level of microfluidic mixing controls compositional ratios. Staggered herringbone micromixers can be used to induce chaotic convection. This allows rapid and homogeneous mixing of two phases on the timescale of milliseconds. The total flow rate and the flow ratio of the two phases can be adjusted independently to tune particle size and encapsulation efficiency. For example, increasing the total flow rate by a factor of 2 halves the mixing time, which improves size distribution. By altering the ratio of solvents it is possible to increase the encapsulation efficiency from 70% to 95%. Composition optimization for selective organ accumulation has been demonstrated. By changing the type of helper lipids it is possible to achieve selective organ targeting while maintaining the same particle size. For example, by replacing the neutral helper lipids with cationic lipids LNPs are selectively targeted towards the lungs. On the other hand, using anionic lipids allows LNPs to accumulate in the spleen.
Table 7. Impact of Physicochemical Parameters on Lipid Nanoparticle Performance.
| Parameter | Optimized Range | Effect if Too Low | Effect if Too High | Optimal Outcome |
| Particle size | 80–150 nm | Rapid renal clearance | Reticuloendothelial capture | Maximized tissue accumulation |
| ζ-potential | –5 to +5 mV | Low cellular uptake | Increased protein adsorption | Stable circulation with efficient uptake |
| Ionizable lipid ratio | 30–50% | Poor encapsulation | Increased toxicity | Efficient and reliable delivery |
| PEG density | 1.5–2.5% | Rapid clearance | Impaired uptake | Balanced stealth and uptake |
| Cholesterol content | 35–45% | Structural instability | Reduced fusion | Controlled release with integrity |
Continuous production of LNPs has been demonstrated using microfluidic platforms. Batch processing is associated with limitations in reproducibility, complex scale-up, and extended production times. In microfluidic continuous flow platforms, mixing times in the millisecond range can be reached under laminar flow conditions by introducing a staggered herringbone mixer to increase transverse mixing. Commercial platforms can achieve flow rates of a few hundred milliliters per minute with high control over particle properties. Parallelization of microfluidic channels allows for linear scaling of capacity. By using multiple channels, a higher throughput can be achieved while maintaining the microscale mixing conditions and the resulting quality. Macro-scale microfluidic devices with significantly higher flow rates in the range of liters per minute have been demonstrated. Lyophilization, or freeze-drying, is an attractive approach to provide long-term storage of LNPs. Freeze-drying LNPs with cryoprotectants like sucrose or trehalose can produce a solid powder that experiences minimal changes when it is reconstituted. Optimized lyophilization has resulted in <10 nm increases in the variation in particle size and encapsulation efficiency remaining at or above 95% when the particles are reconstituted. Lyophilized LNPs can remain stable at ambient temperatures for months or years, which eases logistics. Process analytical technologies (PAT) have also been explored for continuous LNP production. Inline dynamic light scattering is used to measure particle size during production, and spectroscopic and chromatographic approaches have been used to assess encapsulation efficiency and lipid composition. Feedback control strategies can be employed to adjust processing parameters based on the measured data and thus maintain quality within tight specifications, thereby improving yield. Continuous, closed-system LNP production platforms have also been developed that have the potential to increase process safety by shortening production time from days to hours and minimizing contamination risk, while also allowing for continuous operation.
Table 8. Lipid Nanoparticle Development and Engineering Services.
| Service | Description | Price |
| LNP Formulation Development | Systematic optimization of ionizable lipids, helper lipids, cholesterol, and PEG ratios based on nucleic acids, small molecules, or proteins to support specific delivery and performance objectives. | Inquiry |
| Microfluidic LNP Preparation and Process Development | Continuous LNP fabrication using microfluidic platforms with precise control of particle size (20–150 nm), size distribution, and encapsulation efficiency, suitable for scalability and high reproducibility. | Inquiry |
| Targeted LNP Surface Engineering | Design and implementation of antibody, peptide, small-molecule, and glycosylation modifications to enable directed delivery to liver, brain, immune cells, and other target tissues. | Inquiry |
| Lipid Nanoparticles for Drug Delivery | Develop lipid nanoparticle systems to enhance solubility, stability, and targeted delivery of small molecules and biologics for improved therapeutic efficacy. | Inquiry |
| LNP Stability Evaluation Services | Stability assessment for liquid and lyophilized formulations, including formulation optimization, cryoprotectant screening, and reconstitution performance evaluation under ambient or refrigerated conditions. | Inquiry |
| LNP Characterization Services | Comprehensive physicochemical characterization including particle size, PDI, surface charge, encapsulation efficiency, and release behavior to support formulation optimization and technical validation. | Inquiry |
| Continuous and Scalable Manufacturing Process Design | Process translation support from laboratory to pilot scale, including multi-channel microfluidic scale-up, inline monitoring strategies, and integrated workflow design. | Inquiry |
Overall, lipid nanoparticle manufacturing is transitioning from laboratory-scale preparation to industrial production. The integration of microfluidics, lyophilization, and real-time analytics addresses key challenges in reproducibility, stability, and scalability. As these technologies mature, production efficiency will continue to improve, expanding access to advanced delivery solutions across a broad range of applications.
