The central concept of cell-targeted nanoparticle delivery is to ensure that therapeutic or bioactive molecules reach effective concentrations at the right time and within the intended cellular compartment. By rationally designing nanoparticles in terms of size, morphology, surface charge, and chemical composition, it is possible to achieve prolonged circulation in blood, lymph, or interstitial fluids while exploiting the differential molecular signatures expressed on cell surfaces. This enables a transition from nonspecific systemic exposure to precise cell-level targeting.
Over the past two decades, extensive studies have demonstrated that PEGylated lipid vesicles or polymeric nanocapsules with diameters of 30–150 nm preferentially penetrate tumor stroma, whereas smaller and stiffer inorganic nanoparticles exhibit superior ability to traverse dense fibrous barriers. Regardless of material composition, the cell-targeting process consists of four interconnected stages: membrane contact, endocytosis, intracellular trafficking, and functional payload release, each of which can be finely tuned through engineering strategies to enhance delivery efficiency and selectivity.
1. Amplified Intracellular Concentration
By engineering nanoparticles to recognize cell-specific surface receptors, active molecules can be concentrated precisely at the intended site of action. For instance, hyaluronic acid nanoparticles functionalized to target CD44 receptors markedly increase the nuclear uptake of encapsulated compounds, achieving over tenfold enhancement compared with unformulated molecules, while simultaneously reducing nonspecific tissue exposure. This selective accumulation allows for efficient biological activity at lower overall doses, improving delivery economy and minimizing systemic burden.
2. Tailored Pharmacokinetic Behavior
Nanocarriers can also be designed to reshape circulation and clearance profiles, providing sustained molecular stability in dynamic biological environments. Vitamin A-conjugated polylactide nanoparticles, for example, exhibit extended residence time in target cells, allowing nucleic acid-based agents to maintain functional activity over several hours rather than minutes. This temporal control ensures consistent exposure at the cellular level, which is particularly valuable for molecules prone to rapid degradation.
3. Functional and Analytical Integration
Modern nanocarrier systems increasingly combine therapeutic and analytical capabilities within a unified construct. A single carrier co-loaded with rapamycin and a near-infrared fluorophore exemplifies this approach, enabling both molecular pathway regulation and real-time visualization of spatial distribution. Such dual functionality supports a data-driven understanding of delivery performance, offering an integrated tool for correlating material behavior with biological outcomes.
4. Reduced Immunological Interference
Surface modification strategies further enhance the biocompatibility and tolerability of nanocarriers. For example, a PEG–polyglutamic acid copolymer shell effectively minimizes complement activation, reducing immune recognition and promoting stable systemic performance. This "stealth" characteristic allows repeated dosing and prolonged circulation without compromising nanoparticle integrity or function.
Despite notable advances, achieving precise delivery at the cellular scale remains technically demanding.
Heterogeneity is a primary challenge. Within the same tissue microenvironment, peripheral and hypoxic regions may differ substantially in vascular density, membrane protein expression, and endocytic activity, leading to nonuniform nanoparticle distribution characterized by "hot" and "cold" zones.
A second barrier is protein corona formation. Within minutes of exposure to plasma, nanoparticles adsorb a complex array of 50–200 proteins. Immunoglobulins and complement fragments can competitively block ligand–receptor interactions, thereby diminishing targeting efficiency.
The third challenge arises from intracellular entrapment. Even when nanoparticles successfully enter cells, more than 60% of the payload may undergo lysosomal degradation, preventing it from reaching the intended cytoplasmic or nuclear sites.
Finally, scalability remains an engineering hurdle. Microfluidic systems can generate liposomes with size dispersity below 10%; however, during scale-up production, turbulence and temperature gradients can increase batch-to-batch variation to as high as 25%, posing challenges to manufacturing consistency and performance reproducibility.
Passive targeting relies primarily on enhanced vascular permeability and retention effects. In tumor, inflammatory, or ischemic tissues, endothelial gaps may reach 100–800 nm, five to twenty times larger than those in normal vessels, allowing nanoparticles to extravasate. However, impaired lymphatic drainage prolongs nanoparticle residence time, creating a "one-way entry, slow clearance" pattern.
Flexible polymeric micelles of 40–80 nm typically reach their maximum intratumoral concentration within 4–6 hours after administration, whereas rigid particles of around 200 nm may require up to 24 hours. Surface charge also influences penetration depth: nanoparticles with a mild negative charge (~–10 mV) experience minimal electrostatic repulsion from collagen fibers and can infiltrate up to 50 μm into dense tissue. Beyond vascular transport, lymphatic targeting is also feasible. Liposomes around 20 nm in diameter can enter initial lymphatic capillaries and be internalized by resident macrophages within lymph nodes, enabling localized delivery of immunomodulatory agents.
Active targeting builds upon passive accumulation to achieve higher cellular selectivity. High-affinity ligands bind to overexpressed membrane receptors, triggering clathrin- or caveolin-mediated endocytosis and facilitating cellular uptake. For instance, folate receptors are upregulated by 10–100 fold in certain tumor cell types, with up to 106 receptor copies per cell surface; nanomolar concentrations of folate ligands are sufficient for receptor saturation.
Glycan-modified systems also demonstrate strong specificity. Mannose–chitosan nanoparticles exhibit a binding constant (Kd) of approximately 10 nM with macrophage surface DC-SIGN receptors, enhancing intracellular accumulation of bioactive compounds by up to eightfold. Moreover, multivalent binding significantly boosts overall affinity: nanoparticles functionalized with 20–40 aptamers can exhibit two orders of magnitude higher apparent binding strength than monovalent ligands, effectively targeting subpopulations with low receptor expression.
To prevent premature ligand exposure during circulation, researchers have introduced pH-sensitive cleavable linkers that conceal ligands under physiological pH (7.4) and reveal them only within acidic microenvironments. This "stealth-then-recognize" strategy enhances delivery precision by synchronizing activation with the target milieu.
Fig.1 Nanoparticle-mediated drug transport to tumors1,2.
Once internalized, nanoparticles are first enclosed in early endosomes (pH 6.0–6.5), then transition to late endosomes (pH 5.0–5.5), and finally fuse with lysosomes, where enzymatic activity is substantially enhanced. Timely endosomal escape is therefore critical to preserving payload integrity.
Key strategies include:
Proton Sponge Effect: Polyethylenimine or polyhistidine buffers acidic environments by absorbing protons, inducing ion influx, osmotic swelling, and endosomal rupture.
Membrane Fusion Mechanism: DOPE–cholesterol hemisuccinate undergoes a hexagonal phase transition at pH 6.5, merging with the endosomal membrane and forming transient pores that release siRNA directly into the cytoplasm.
Photothermal Triggering: Gold nanorods generate localized heating under 808 nm irradiation, transiently permeabilizing endosomal membranes and enabling rapid cargo release.
Magneto-Mechanical Disruption: Iron oxide nanoparticles exposed to a rotating magnetic field produce nanoscale torque, physically perforating the endosomal membrane with high release efficiency while maintaining cell viability.
Intracellular release must be spatially precise and temporally controlled. The cytosolic concentration of glutathione (2–10 mM) is roughly 1000 times higher than in blood (2–20 μM), allowing disulfide-crosslinked polymeric micelles to rapidly cleave and discharge their payloads within seconds after cellular entry.
Elevated levels of reactive oxygen species (ROS), typically 10–20 times higher under oxidative stress, can trigger thioketal bond cleavage in ROS-sensitive nanoparticles, leading to hydrophobic-to-hydrophilic conversion and accelerated release within 20 minutes.
Enzyme-responsive systems exploit the overexpression of matrix metalloproteinase-2 (MMP-2), which cleaves peptide linkers on nanoparticle surfaces, unmasking cationic domains that strengthen electrostatic interactions and promote cellular penetration.
Thermo-responsive carriers leverage lipid bilayer fluidization above 40 ℃, enabling temperature-controlled release within localized heating environments.
Furthermore, multi-stimuli-responsive designs improve targeting precision. For example, "acid + enzyme" dual-gated nanoparticles release their payload only under acidic conditions (pH < 6.5) in the presence of MMP-2, demonstrating a threefold increase in release efficiency compared with single-trigger systems, while maintaining below 10% nonspecific leakage.
BOC Sciences provides versatile nanoparticles with diverse compositions and functional modifications, customized solutions for your delivery needs.
Delivering genetic materials such as DNA, mRNA, or siRNA into living cells represents a cornerstone in functional genomics and molecular mechanism studies. Lipid-based nanoparticles are particularly effective for this purpose due to their ability to self-assemble with nucleic acids and protect them from enzymatic degradation. Typically, an ionizable lipid shell acquires a positive charge under mildly acidic conditions, promoting electrostatic interaction with the negatively charged cell membrane and facilitating endocytosis. This architecture significantly enhances transfection efficiency, often by two orders of magnitude compared with naked nucleic acids.
For siRNA applications, nanoparticles decorated with carbohydrate ligands can recognize hepatocyte-specific receptors, achieving potent gene silencing at relatively low doses while minimizing off-target responses. Similarly, mRNA delivery systems employ comparable design principles—once the desired antigen sequence is incorporated, the nanocarrier directs intracellular translation within hepatocytes or splenic cells, resulting in transient but robust protein production.
In the case of larger DNA plasmids, polymer–gold hybrid nanoparticles are frequently used to enhance cellular entry. Under light or magnetic stimulation, transient pores can be formed in endosomal membranes, enabling the release of plasmids into the cytoplasm and subsequent nuclear localization. Such platforms have become standard tools for studies involving gene regulation, cell signaling, and synthetic biology, enabling reproducible and efficient manipulation of gene expression in target cell populations.
Protein and enzyme delivery requires more refined strategies due to their structural fragility and susceptibility to lysosomal degradation. Researchers often encapsulate enzymes within lipid vesicles or polymeric nanocapsules, further decorating their surfaces with targeting moieties specific to subcellular compartments. For instance, catalase encapsulated in targeted vesicles can be directed to hypoxic regions, where it locally decomposes hydrogen peroxide and reduces oxidative stress. Similarly, enzyme-loaded nanoparticles engineered for macrophage uptake can restore defective metabolic pathways by degrading accumulated substrates.
When precise control over protein function is desired, systems can co-deliver functional proteins such as Cas9 ribonucleoprotein complexes along with guide RNAs. Equipped with nuclear localization sequences, these complexes directly enter the nucleus, enabling genome editing within hours, bypassing transcription and translation steps and reducing unintended effects. Stimuli-responsive designs, such as temperature- or light-triggered release, further enhance temporal control, allowing researchers to activate or deactivate specific protein functions in real time.
Integrating imaging and delivery within a single nanoplatform enables simultaneous visualization and functional modulation of cellular processes. Quantum dots, gold nanoclusters, and magnetic nanoparticles serve as highly stable signal sources. When encapsulated within lipid or polymeric shells, these nanoparticles retain their fluorescence or magnetic responsiveness while gaining improved biostability. Surface conjugation with cell-specific ligands enables selective accumulation at target cell membranes, resulting in signal amplification and higher spatial resolution.
Fluorescent probes emitting in the near-infrared range can penetrate several hundred micrometers, providing real-time visualization of tumor boundaries or tissue remodeling in live models. Magnetic nanoparticles, detectable across whole organisms, allow tracking of stem cell migration and engraftment dynamics. Meanwhile, two-photon excitation systems using these functional nanoparticles can reveal intricate neuronal synapses deep within tissue. The protective nanocarrier matrix prevents quenching and clearance, extending observation periods from hours to several weeks, sufficient to monitor full biological cycles such as inflammation progression or tissue regeneration.
Regenerative biology relies on precise spatial and temporal coordination of signaling molecules. Growth factors or nucleic acids delivered directly often suffer from rapid diffusion and degradation, limiting their local effectiveness. Nanoparticle systems address this limitation by anchoring bioactive agents to damaged sites and releasing them in a controlled manner. This sustained presentation guides cell proliferation, angiogenesis, and differentiation in an orderly sequence.
For example, mRNA-loaded nanofibers that gradually degrade with cardiac contractions have been shown to promote concurrent angiogenesis and myocardial tissue formation. In cartilage repair, chondroitin sulfate–modified nanoparticles adhere to collagen matrices and deliver transforming factors specifically to chondrocytes, minimizing undesired ossification. More advanced formulations are responsive to biochemical cues such as reactive oxygen species or pH gradients, enabling selective release of immunomodulatory agents at sites of inflammation. By modulating macrophage polarization and reshaping the cellular microenvironment, these systems create favorable conditions for subsequent stem cell recruitment and tissue regeneration.
Nanoparticles serve as versatile delivery vehicles capable of transporting therapeutic or diagnostic agents precisely to target cells while minimizing off-target exposure. Depending on their composition and structural characteristics, cell-targeted nanoparticles can be broadly classified into several major categories.
Lipid-based nanoparticles are among the most extensively studied delivery systems due to their inherent biocompatibility and structural versatility. Liposomes, composed of phospholipid bilayers, can encapsulate both hydrophilic and hydrophobic molecules, providing a flexible platform for controlled release and surface modification. The lipid surface can be easily functionalized with targeting ligands to enable selective cellular recognition.
Solid lipid nanoparticles (SLNs) use lipids that remain solid at room and body temperature, offering enhanced encapsulation stability and controlled release kinetics compared with conventional emulsions. Nanostructured lipid carriers (NLCs) represent an advanced form of SLNs, incorporating liquid lipids into the crystalline matrix. This structural disruption increases drug-loading capacity and reduces the risk of premature leakage, creating a more adaptable and stable delivery system.
Polymeric nanoparticles are typically fabricated from biodegradable materials such as poly(lactic-co-glycolic acid) (PLGA) or chitosan. Their tunable degradation rates allow sustained release of encapsulated agents over extended periods, ranging from several days to weeks. By covalently linking targeting molecules, such as antibodies, peptides, or aptamers, to their surfaces, polymeric nanoparticles gain active targeting capability, enabling selective cellular uptake and controlled biodistribution.
Dendrimers are synthetic, highly branched macromolecules with well-defined architecture and abundant surface functional groups. This structural precision facilitates efficient drug conjugation and multivalent ligand attachment, allowing a single dendrimer to carry multiple targeting motifs. The resulting multivalency enhances binding affinity to cellular receptors, improving uptake efficiency and intracellular localization.
Inorganic nanoparticles occupy a distinctive position in cell-targeted delivery owing to their unique optical, magnetic, and mechanical properties. Gold nanoparticles exhibit tunable surface plasmon resonance, making them valuable for imaging, sensing, and photothermal applications. Their surfaces can be functionalized via thiol-gold chemistry, enabling stable conjugation of biomolecules for targeted delivery or signal enhancement.
Silica nanoparticles, particularly mesoporous silica, possess uniform pore structures with exceptionally high surface area and pore volume, providing excellent capacity for drug adsorption or covalent immobilization. Their adjustable pore size allows for controlled release behavior and co-delivery of multiple agents. Magnetic nanoparticles, typically composed of iron oxide cores, can be guided by external magnetic fields to achieve site-specific accumulation. They are also widely used as contrast agents in imaging applications, allowing integration of diagnostic and therapeutic functions within a single nanoplatform.
Hybrid nanocarriers are engineered to combine the advantages of different material classes while overcoming their individual limitations. A typical hybrid system may contain a polymeric core for efficient drug loading, a lipid shell to enhance biocompatibility and prolong circulation, and surface-bound targeting ligands to promote specific cell recognition. Additionally, embedded inorganic components, such as gold nanorods or magnetic nanoparticles, can introduce imaging or photothermal functionalities.
This modular, multifunctional design enables simultaneous delivery, targeting, and diagnostic monitoring, offering a comprehensive platform for complex biomedical applications where multiple mechanisms, chemical, physical, and biological, must operate in concert.
Table 1. Representative categories of nanoparticles for targeted delivery.
| Product Category | Representative Materials | Core Advantages | Example Applications | Inquiry |
| Lipid nanoparticles | Phospholipids, cholesterol, solid lipids | High biocompatibility, facile preparation, dual drug loading | Liposomes for targeted small-molecule delivery; SLNs/NLCs for transdermal applications | Inquiry |
| Polymeric nanoparticles | PLGA, chitosan, polyethyleneimine | Controlled degradation, extended release, structural robustness | PLGA nanoparticles for vaccine adjuvant delivery; chitosan nanoparticles for gene transfer | Inquiry |
| Dendrimers | Poly(amidoamine) (PAMAM) | Precise architecture, high surface density for multivalent targeting | PAMAM–folate conjugates for receptor-mediated targeting and imaging | Inquiry |
| Inorganic nanoparticles | Gold, silica, iron oxide | Unique optical/magnetic features, superior stability | Gold nanorods for photothermal therapy; magnetic nanoparticles for guided delivery and imaging | Inquiry |
| Hybrid nanocarriers | Combinations (e.g., lipid–polymer) | Functional integration, tunable performance, synergistic effects | Polymer–lipid hybrid systems for combined drug and gene co-delivery | Inquiry |
Achieving effective cell-targeted delivery depends not only on material selection but also on precise engineering of the nanoparticle's physical and chemical properties. Each design parameter, surface functionality, particle size, charge, morphology, release profile, and biocompatibility, plays a decisive role in performance optimization.
Surface modification is the cornerstone of active targeting. It involves covalent or noncovalent attachment of molecules that can recognize specific antigens or receptors on cell membranes. Common ligands include antibodies and their fragments (for high specificity), small molecules such as folate (targeting overexpressed folate receptors), peptides like RGD sequences (binding to integrins on angiogenic endothelium or certain tumor cells), and aptamers, which are nucleic acid-based ligands selected for strong affinity and selectivity. The density, orientation, and accessibility of these ligands critically influence binding kinetics and cellular internalization efficiency.
The physicochemical characteristics of nanoparticles profoundly affect their in vivo transport and cellular uptake mechanisms.
Size: Particles in the 10–200 nm range favor accumulation in target tissues through enhanced permeability and retention, while avoiding rapid renal clearance.
Surface Charge: Near-neutral or slightly negative zeta potential minimizes nonspecific protein adsorption, extending circulation time. Conversely, positively charged surfaces enhance electrostatic interaction with negatively charged cell membranes but may increase cytotoxicity risk.
Shape: Morphology influences hydrodynamics and uptake pathways—rod-shaped or disk-like particles often exhibit prolonged circulation and distinct endocytic profiles compared with spherical particles.
An ideal targeted nanocarrier must remain structurally stable during transport while releasing its payload selectively at the target site. Controlled release can be achieved by designing stimuli-responsive systems that react to local conditions such as acidic pH, elevated glutathione concentration, or specific enzymatic activity. These triggers induce structural transformations or bond cleavage, promoting on-demand release. Stability, in turn, involves preventing aggregation, degradation, or premature leakage during storage and circulation, which can be addressed through formulation optimization and protective surface coatings.
Biocompatibility is fundamental to the successful integration of nanocarriers within biological systems. Materials and their degradation products must be non-toxic and should not elicit strong immune or inflammatory responses.
Cell–nanoparticle interactions are inherently dynamic: the process begins with surface contact mediated by electrostatic, hydrophobic, or ligand–receptor interactions, followed by cellular internalization via clathrin-mediated endocytosis, caveolae-mediated endocytosis, or macropinocytosis. Once internalized, the fate of the nanoparticle, whether degraded in endosomal compartments or escaping into the cytoplasm, determines the bioavailability of its cargo. Understanding these interaction dynamics is therefore essential to engineering systems that achieve efficient intracellular delivery and functional performance.
Table 2. Key design parameters and their biological implications.
| Design Parameter | Optimization Objective | Key Biological Implications |
| Particle size | 10–200 nm | Promotes accumulation in target tissues, avoids renal filtration; extremes may lead to clearance or phagocytic capture |
| Surface charge | Near-neutral or mildly negative | Reduces nonspecific protein binding and prolongs circulation; excessive positive charge may increase toxicity |
| Shape | Spherical, rod-like, or disk-like | Influences flow dynamics, internalization routes, and retention time |
| Surface functionalization | Ligand conjugation | Enables active targeting and enhanced uptake; requires balance between ligand density and biocompatibility |
| Release mechanism | Stimuli-responsive or sustained | Ensures on-site release; kinetics must align with biological activity requirements |
Comprehensive analytical characterization is essential to ensure that cell-targeted nanoparticle systems perform predictably in terms of stability, loading efficiency, and cellular interaction. Each analytical dimension provides insight into how material design translates into biological function.
Particle size and polydispersity critically determine nanoparticle transport and cellular uptake behavior. Dynamic light scattering (DLS) remains the standard method for measuring hydrodynamic diameter and distribution uniformity. Complementarily, zeta potential analysis evaluates surface charge, serving as an indicator of colloidal stability and interaction tendency with cell membranes. High absolute zeta potential values (typically above ±30 mV) indicate strong electrostatic repulsion, which helps prevent aggregation and maintain dispersion stability over time.
Surface modification defines the targeting and biointeraction properties of nanocarriers. X-ray photoelectron spectroscopy (XPS) enables quantitative analysis of surface elemental composition and verifies successful ligand conjugation. Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) provide molecular-level evidence of specific chemical bonds and functional groups. Fluorescence labeling further facilitates direct visualization. By covalently attaching a fluorophore to the targeting ligand, researchers can confirm conjugation success through spectral signal detection.
Loading capacity and encapsulation efficiency are central to evaluating nanocarrier performance. High-performance liquid chromatography (HPLC) is the preferred technique for precise quantification, allowing differentiation between encapsulated and free drug fractions. Release kinetics are typically assessed under simulated physiological conditions (e.g., in buffer solutions at 37 ℃) by sampling at predefined intervals and quantifying the released drug concentration. These data establish the nanocarrier's capability for sustained or stimuli-responsive release, which directly affects its bioactivity profile.
Understanding intracellular fate is vital for optimizing nanocarrier design. Transmission electron microscopy (TEM) provides ultrastructural localization, revealing whether nanoparticles remain within endosomes or have escaped into the cytosol. Confocal laser scanning microscopy (CLSM), combined with fluorescent labeling of both nanoparticles and organelles, enables precise co-localization analysis and visualization of trafficking pathways. These imaging modalities together offer crucial insight into nanoparticle–cell interaction dynamics, guiding further refinement toward improved cellular delivery efficiency and functionality.
Table 3. Analytical Services for Characterization of Cell-Targeted Nanoparticle Systems.
| Service | Analytical Techniques | Information Provided | Inquiry |
| Particle Size Measurement | Dynamic Light Scattering (DLS) | Determines the mean hydrodynamic diameter of nanoparticles and assesses particle scaling behavior in suspension. | Inquiry |
| Particle Distribution Profiling | Dynamic Light Scattering (DLS) | Evaluates uniformity through polydispersity index (PDI), reflecting formulation consistency and aggregation tendency. | Inquiry |
| Surface Charge Analysis | Zeta Potential Measurement | Measures nanoparticle surface charge to assess electrostatic stability and predict dispersion performance. | Inquiry |
| Surface Functionalization Validation | Fourier Transform Infrared Spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS) | Confirms successful surface modification and verifies the presence of specific chemical functionalities. | Inquiry |
| Drug Loading Efficiency Determination | High-Performance Liquid Chromatography (HPLC), UV–Visible Spectrophotometry | Quantifies encapsulated versus unbound active molecules to assess formulation efficiency. | Inquiry |
| Controlled Release Profiling | HPLC, UV–Visible Spectrophotometry | Measures time-dependent release kinetics under simulated physiological or environmental conditions. | Inquiry |
| Cellular Localization Analysis | Transmission Electron Microscopy (TEM) | Provides ultrastructural visualization of nanoparticle positioning relative to subcellular organelles. | Inquiry |
BOC Sciences offers comprehensive solutions for cell-targeted nanoparticle delivery, enabling selective intracellular transport through precise control of nanoparticle physicochemical properties, surface functionalization, and payload characteristics. The company provides a diverse portfolio of delivery platforms, including lipid-based nanoparticles, polymeric nanoparticles, dendrimers, inorganic nanoparticles, and multifunctional hybrid systems, allowing researchers to optimize performance for a variety of experimental contexts. These carriers enhance the intracellular concentration of active molecules via both passive and active targeting mechanisms, while also supporting controlled release triggered by endogenous or exogenous stimuli, thereby improving bioactivity and minimizing exposure to non-target cells.
In terms of applications, BOC Sciences supports efficient intracellular delivery of genetic materials (DNA, mRNA, siRNA), enzymes, and other bioactive molecules; provides functionalized nanoparticles for cellular imaging, tracking, and quantitative analysis; and offers customized delivery systems for regenerative research and cellular microenvironment modulation. Complementing these platforms, BOC Sciences also provides comprehensive characterization services, including particle size and distribution analysis, surface chemistry and functional group validation, drug loading and release profiling, and intracellular localization studies, enabling researchers to systematically evaluate nanoparticle behavior in biological systems and generate reliable data for optimizing delivery efficiency and functionality.
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