Experimental and theoretical explorations of nanocarriers' multistep delivery performance for rational design and anticancer prediction

Curvature-mediated rapid extravasation and penetration of nanoparticles against interstitial fluid pressure for improved drug delivery

Elevated interstitial fluid pressure (IFP) within pathological tissues (e.g., tumors, obstructed kidneys, and cirrhotic livers) creates a significant hindrance to the transport of nanomedicine, ultimately impairing the therapeutic efficiency. Among these tissues, solid tumors present the most challenging scenario. While several strategies through reducing tumor IFP have been devised to enhance nanoparticle delivery, few approaches focus on modulating the intrinsic properties of nanoparticles to effectively counteract IFP during extravasation and penetration, which are precisely the stages obstructed by elevated IFP. Herein, we propose an innovative solution by engineering nanoparticles with a fusiform shape of high curvature, enabling efficient surmounting of IFP barriers during extravasation and penetration within tumor tissues. Through experimental and theoretical analyses, we demonstrate that the elongated nanoparticles with the highest mean curvature outperform spherical and rod-shaped counterparts against elevated IFP, leading to superior intratumoral accumulation and antitumor efficacy. Super-resolution microscopy and molecular dynamics simulations uncover the underlying mechanisms in which the high curvature contributes to diminished drag force in surmounting high-pressure differentials during extravasation. Simultaneously, the facilitated rotational movement augments the hopping frequency during penetration. This study effectively addresses the limitations posed by high-pressure impediments, uncovers the mutual interactions between the physical properties of NPs and their environment, and presents a promising avenue for advancing cancer treatment through nanomedicine.

Cation Triggered Self-Assembly of α-Lactalbumin Nanotubes

Metal ions play a dual role in biological systems. Although they actively participate in vital life processes, they may contribute to protein aggregation and misfolding and thus contribute to development of diseases and other pathologies. In nanofabrication, metal ions mediate the formation of nanostructures with diverse properties. Here, we investigated the self-assembly of α-lactalbumin into nanotubes induced by coordination with metal ions, screened among the series Mn2+, Co2+, Ni2+, Zn2+, Cd2+, and Au3+. Our results revealed that the affinity of metal ions toward hydrolyzed α-lactalbumin peptides not only impacts the kinetics of nanotube formation but also influences their length and rigidity. These findings expand our understanding of supramolecular assembly processes in protein-based materials and pave the way for designing novel materials such as metallogels in biochip and biosensor applications.

Protein Nanotubes as Advanced Material Platforms and Delivery Systems

Protein nanotubes (PNTs) as state-of-the-art nanocarriers are promising for various potential applications both in the food and pharmaceutical industries. Derived from edible starting sources like α-lactalbumin, lysozyme, and ovalbumin, PNTs bear properties of biocompatibility and biodegradability. Their large specific surface area and hydrophobic core facilitate chemical modification and loading of bioactive substances, respectively. Moreover, their enhanced permeability and penetration ability across biological barriers such as intestinal mucus, extracellular matrix, and thrombus clot, make it promising platforms for health-related applications. Most importantly, their simple preparation processes enable large-scale production, supporting applications in the biomedical and nanotechnological fields. Understanding the self-assembly principles is crucial for controlling their morphology, size, and shape, and thus provides the ground to a multitude of applications. Here, the current state-of-the-art of PNTs including their building materials, physicochemical properties, and self-assembly mechanisms are comprehensively reviewed. The advantages and limitations, as well as challenges and prospects for their successful applications in biomaterial and pharmaceutical sectors are then discussed and highlighted. Potential cytotoxicity of PNTs and the need of regulations as critical factors for enabling in vivo applications are also highlighted. In the end, a brief summary and future prospects for PNTs as advanced platforms and delivery systems are included.

Enhancing biofilm penetration and antibiofilm efficacy with protein nanocarriers against pathogenic biofilms

Nanocarriers play an important role in enhancing the efficacy of antibiotics against biofilms by improving their penetration and prolonging retention in pathogenic biofilms. Herein, the multifunctional nanocarriers including nanospheres (NS) and nanotubes (NT) with a high biocompatibility and biodegradability were prepared through self-assembly of partially hydrolyzed α-lactalbumin. The effects of these two different shaped nanocarriers on the delivery of antibiotics for biofilm treatment were examined by conducting in vitro antibiofilm experiment and in vivo infected wound model. The strong affinity of NS and NT for the bacterial surface allows antibiotics to be concentrated in the bacteria. Notably, the high permeability of NT into biofilms facilitates deeper penetration and the easier diffusion of loaded antibiotics within the biofilm. Furthermore, the acidic biofilm environment triggers the release of antibiotics from the NT, resulting in the accumulation of high local antibiotic concentrations. Therefore, NT could efficiently clean and inhibit the biofilm formation while also destroying the mature biofilms. In a S. aureus infected wound animal model, treatment with antibiotic-loaded NT demonstrated accelerated healing of S. aureus infected wounds when compared to free antibiotic treatment. These findings indicate that NT nanocarrier strategy is promising for treating bacterial biofilm infections, offering the potential for lower antibiotics dosages and preventing the overuse of antibiotics.

Chitosomes Loaded with Docetaxel as a Promising Drug Delivery System to Laryngeal Cancer Cells: An In Vitro Cytotoxic Study

Current delivery of chemotherapy, either intra-venous or intra-arterial, remains suboptimal for patients with head and neck tumors. The free form of chemotherapy drugs, such as docetaxel, has non-specific tissue targeting and poor solubility in blood that deters treatment efficacy. Upon reaching the tumors, these drugs can also be easily washed away by the interstitial fluids. Liposomes have been used as nanocarriers to enhance docetaxel bioavailability. However, they are affected by potential interstitial dislodging due to insufficient intratumoral permeability and retention capabilities. Here, we developed and characterized docetaxel-loaded anionic nanoliposomes coated with a layer of mucoadhesive chitosan (chitosomes) for the application of chemotherapy drug delivery. The anionic liposomes were 99.4 ± 1.5 nm in diameter with a zeta potential of -26 ± 2.0 mV. The chitosan coating increased the liposome size to 120 ± 2.2 nm and the surface charge to 24.8 ± 2.6 mV. Chitosome formation was confirmed via FTIR spectroscopy and mucoadhesive analysis with anionic mucin dispersions. Blank liposomes and chitosomes showed no cytotoxic effect on human laryngeal stromal and cancer cells. Chitosomes were also internalized into the cytoplasm of human laryngeal cancer cells, indicating effective nanocarrier delivery. A higher cytotoxicity (p < 0.05) of docetaxel-loaded chitosomes towards human laryngeal cancer cells was observed compared to human stromal cells and control treatments. No hemolytic effect was observed on human red blood cells after a 3 h exposure, proving the proposed intra-arterial administration. Our in vitro results supported the potential of docetaxel-loaded chitosomes for locoregional chemotherapy delivery to laryngeal cancer cells.

Computational modeling of passive transport of functionalized nanoparticles

Functionalized nanoparticles (NPs) are complex objects present in a variety of systems ranging from synthetic grafted nanoparticles to viruses. The morphology and number of the decorating groups can vary widely between systems. Thus, the modeling of functionalized NPs typically considers simplified spherical objects as a first-order approximation. At the nanoscale label, complex hydrodynamic interactions are expected to emerge as the morphological features of the particles change, and they can be further amplified when the NPs are confined or near walls. Direct estimation of these variations can be inferred via diffusion coefficients of the NPs. However, the evaluation of the coefficients requires an improved representation of the NPs morphology to reproduce important features hidden by simplified spherical models. Here, we characterize the passive transport of free and confined functionalized nanoparticles using the Rigid Multi-Blob (RMB) method. The main advantage of RMB is its versatility to approximate the mobility of complex structures at the nanoscale with significant accuracy and reduced computational cost. In particular, we investigate the effect of functional groups' distribution, size, and morphology over nanoparticle translational and rotational diffusion. We identify that the presence of functional groups significantly affects the rotational diffusion of the nanoparticles; moreover, the morphology of the groups and number induce characteristic mobility reduction compared to non-functionalized nanoparticles. Confined NPs also evidenced important alterations in their diffusivity, with distinctive signatures in the off-diagonal contributions of the rotational diffusion. These results can be exploited in various applications, including biomedical, polymer nanocomposite fabrication, drug delivery, and imaging.

The intracellular fate and transport mechanism of shape, size and rigidity varied nanocarriers for understanding their oral delivery efficiency

Nanocarriers have become an effective strategy to overcome epithelial absorption barriers. During the absorption process, the endocytosis mechanisms, cell internalization pathways, and transport efficiency of nanocarriers are greatly impacted by their physical properties. To understand the relationship between physical properties of nanocarriers and their abilities overcoming multiple absorption barriers, nanocarriers with variable physical properties were prepared via self-assembly of hydrolyzed α-lactalbumin peptide fragments. The impacts of size, shape, and rigidity of nanocarriers on epithelial cells endocytosis mechanisms, internalization pathways, transport efficiency, and bioavailability were studied systematically. The results showed that nanospheres were mainly internalized via clathrin-mediated endocytosis, which was then locked in lysosomes and degraded enzymatically in cytoplasm. While macropinocytosis was the primary pathway of nanotubes and transported to the endoplasmic reticulum and Golgi apparatus, resulting in a high drug concentration and sustained release in cytoplasm. Besides, nanotubes can overcome the multi-drug resistance by inhibiting the P-glycoprotein efflux. Furthermore, nanotubes can open intercellular tight-junctions instantaneously and reversibly, which promotes transport into blood circulation. The aqueous solubility of hydrophobic bioactive mangiferin (Mgf) was improved by nanocarriers. Most importantly, the bioavailability of Mgf was the highest for cross-linked short nanotube (CSNT) which outperformed free Mgf and other formulations by in vivo pharmacokinetic studies. Finally, Mgf-loaded CSNT showed an excellent therapeutic efficiency in vivo for the intervention of streptozotocin-induced diabetes. These results indicate that cross-linked α-lactalbumin nanotubes could be an effective nanocarrier delivery system for improving the epithelium cellular absorption and bioavailability of hydrophobic bioactive compounds.

Probing the Interaction Between Supercarrier RBC Membrane and Nanoparticles for Optimal Drug Delivery

Red blood cell (RBC) membrane-hitchhiking nanoparticles (NPs) have been an increasingly popular supercarrier for targeted drug delivery. However, the kinetic details of the shear-induced NP detachment process from RBC in blood flow remain unclear. Here, we perform detailed computational simulations of the traversal dynamics of an RBC-NP composite supercarrier with tunable properties. We show that the detachment of NPs from RBC occurs in a shear-dependent manner which is consistent with previous experiment results. We quantify the NP detachment rate in the microcapillary flow, and our simulation results suggest that there may be an optimal adhesion strength span of 25-40 μJ/m² for rigid spherical NPs to improve the supercarrier performance and targeting efficiency. In addition, we find that the stiffness and the shape of NPs alter the detachment efficiency by changing the RBC-NP contact areas. Together, these findings provide unique insights into the shear-dependent NP release from the RBC surface, facilitating the clinical utility of RBC-NP composite supercarriers in targeted and localized drug delivery with high precision and efficiency.

Platelet Membrane Cloaked Nanotubes to Accelerate Thrombolysis by Thrombus Clot-Targeting and Penetration

Thrombotic diseases have a high rate of mortality and disability, and pose a serious threat to global public health. Currently, most thrombolytic drugs especially protein drugs have a short blood-circulation time, resulting in low thrombolytic efficiency. Therefore, a platelet membrane (Pm) cloaked nanotube (NT-RGD/Pm) biomimetic delivery system with enhanced thrombolytic efficiency is designed. Nanotubes (NT) with an excellent clot-penetration properties are used to load a protein thrombolytic drug urokinase (Uk). Platelet-targeting arginine glycine-aspartic peptide (RGD) is grafted onto the surface of the nanotubes (NT-RGD) prior to cloaking. Multiple particle tracking (MPT) technique and confocal laser scanning microscope (CLSM) analysis are applied and the results show that the nanotubes possess a strong penetration and diffusion capacity in thrombus clots. After the Pm cloaking on NT-RGD/Uk, it shows a thrombus microenvironmental responsive release property and the half-life of Uk is six times longer than that of free Uk. Most importantly, NT-RGD-Uk/Pm exhibits a 60% thrombolytic efficiency in the FeCl₃ -induced thrombosis mouse model, and it is able to significantly reduce the bleeding side effects of Uk. This Pm-cloaked nanotube system is an effective and promising platform for the controlled and targeted delivery of drugs for the thrombus treatment.

Membrane-Specific Binding of 4 nm Lipid Nanoparticles Mediated by an Entropy-Driven Interaction Mechanism

Lipid nanoparticles (LNPs) are a leading biomimetic drug delivery platform due to their distinctive advantages and highly tunable formulations. A mechanistic understanding of the interaction between LNPs and cell membranes is essential for developing the cell-targeted carriers for precision medicine. Here the interactions between sub 10 nm cationic LNPs (cLNPs; e.g., 4 nm in size) and varying model cell membranes are systematically investigated using molecular dynamics simulations. We find that the membrane-binding behavior of cLNPs is governed by a two-step mechanism that is initiated by direct contact followed by a more crucial lipid exchange (dissociation of cLNP's coating lipids and subsequent flip and intercalation into the membrane). Importantly, our simulations demonstrate that the membrane binding of cLNPs is an entropy-driven process, which thus enables cLNPs to differentiate between membranes having different lipid compositions (e.g., the outer and inner membranes of bacteria vs the red blood cell membranes). Accordingly, the possible strategies to drive the membrane-targeting behaviors of cLNPs, which mainly depend on the entropy change in the complicated entropy-enthalpy competition of the cLNP-membrane interaction process, are investigated. Our work unveils the molecular mechanism underlying the membrane selectivity of cLNPs and provides useful hints to develop cLNPs as membrane-targeting agents for precision medicine.

Heterogeneous Nanostructures Cause Anomalous Diffusion in Lipid Monolayers

The diffusion and mobility in biomembranes are crucial for various cell functions; however, the mechanisms involved in such processes remain ambiguous due to the complex membrane structures. Herein, we investigate how the heterogeneous nanostructures cause anomalous diffusion in dipalmitoylphosphatidylcholine (DPPC) monolayers. By identifying the existence of condensed nanodomains and clarifying their impact, our findings renew the understanding of the hydrodynamic description and the statistical feature of the diffusion in the monolayers. We find a universal characteristic of the multistage mean square displacement (MSD) with an intermediate crossover, signifying two membrane viscosities at different scales: the short-time scale describes the local fluidity and is independent of the nominal DPPC density, and the long-time scale represents the global continuous phase taking into account nanodomains and increases with DPPC density. The constant short-time viscosity reflects a dynamic equilibrium between the continuous fluid phase and the condensed nanodomains in the molecular scale. Notably, we observe an "anomalous yet Brownian" phenomenon exhibiting an unusual double-peaked displacement probability distribution (DPD), which is attributed to the net dipolar repulsive force from the heterogeneous nanodomains around the microdomains. The findings provide physical insights into the transport of membrane inclusions that underpin various biological functions and drug deliveries.

iRGD-grafted N-trimethyl chitosan-coated protein nanotubes enhanced the anticancer efficacy of curcumin and melittin

Curcumin (Cur) and Melittin (Mel) are two natural extracts that have been shown anti-tumor effects. However, their applications are limited due to poor oral bioavailability and the lack of tumor-targeting property. Here, we developed a novel nanocomposite that enabled the co-delivery of Cur and Mel, which consists of α-lactalbumin protein nanotubes (NTs), positively charged N,N,N-trimethyl chitosan (TMC), and a tumor-targeting cyclic peptide iRGD. The results showed that NTs/Cur-TMC-Mel-iRGD incorporated the advantages of each component, for instance, effective compounds loading by NTs, improved cellular uptake by TMC, prolonged accumulation in tumors by iRGD as well as synergistic anti-tumor effects of Cur and Mel. In the tumor-bearing mice, NTs/Cur-TMC-Mel-iRGD treatment remarkably induced cancer cell apoptosis while inhibiting cell proliferation, leading to suppressed tumor growth. Besides, no obvious adverse effects were observed in the blood physiology and tissue histology. Overall, our study provided an effective strategy for co-delivering Cur and Mel, which has a potential for translational clinical research aiming to treat solid tumors.

Force-driven active dynamics of thin nanorods in unentangled polymer melts

Recent advances in the functional material and biomedical applications of nanorods call for a fundamental understanding of the active motion of nanorods in a viscoelastic medium. Molecular dynamics simulations are performed to investigate a model system consisting of force-driven active thin nanorods in a melt of unentangled polymers. The activeness of a thin nanorod arises from a constant external force applied uniformly along the rod. The simulations demonstrate that the active force overcomes the randomness of the diffusive motion and results in a ballistic motion along the direction of the applied force at long timescales. The constant speed of the force-driven ballistic motion is determined by the balance of the active force and the friction from the coupling of the nanorod with the polymer viscosity. The friction coefficient, which is computed as the ratio of the active force and the speed, decreases as the active force increases. The origin of the reduction in the friction coefficient is the high speed that allows the nanorod to renew its local environment faster than the relaxation time of melt chains. A scaling theory is developed to quantify the dependence of the friction coefficient on the strength of the active force. The simulations also demonstrate that the force-driven ballistic motion suppresses the rotational diffusion of the rod and cuts off the de-correlation of the rod axis with time. On the scaling level, the long-time trajectory of a force-driven active nanorod piercing through unentangled polymers may be described as a stretched array of "active blobs", where the short-time random-walk trajectory within an active blob is unperturbed by the active force.

Intestinal-targeted nanotubes-in-microgels composite carriers for capsaicin delivery and their effect for alleviation of Salmonella induced enteritis

Salmonella is a word-wide food-borne pathogen, which can cause severe enteritis and intestinal microbiota imbalance. Capsaicin (Cap), a food-based bioactive ingredient, has antibacterial and anti-inflammatory properties. However, its low solubility, low bioavailability and the irritation to digestive tract greatly limit its applications. Here, an intestinal responsively "nanotubes-in-microgel" composite carrier was constructed by capturing α-lactalbumin (α-lac) nanotubes in low-methoxy pectin microgels (LMP-NT) (52 μm). Cap was loaded in such system via hydrophobic interaction with a loading capacity of 38.02 mg/g. The LMP microgels remained stable and protected NT/Cap from early releasing in the gastric condition. It showed an excellent mucoadhesive capacity, which can prolong the intestinal retention up to 12 h and control release NT/Cap in intestine. Afterward, NT/Cap could penetrate across the mucus layer deeply and enter the intestinal villi epithelial cells efficiently. LMP-NT microgels achieved a mucoadhesive-to-penetrating transition in response to intestinal pH, improving the epithelium absorption and the in vivo bioavailability of Cap. Oral administration of LMP-NT/Cap could effectively alleviate enteritis caused by Salmonella infection and maintain the homeostasis of gut microbiota. Overall, this work suggested that LMP-NT composite microgels were promising for intestine-targeted and oral delivery of hydrophobic bioactive food compounds.

Glucose-sensitive delivery of tannic acid by a photo-crosslinked chitosan hydrogel film for antibacterial and anti-inflammatory therapy

A glucose-sensitive antibacterial and anti-inflammatory hydrogel film with controlled release of tannic acid (TA) was synthesized using chitosan (CS). Specifically, the photo-crosslinked CS hydrogel was first obtained and then immersed in TA solution to generate composite hydrogel film with enhanced mechanical properties. Subsequently, N-hydroxysuccinimide/1-ethyl-3-(3-dimethylaminopropyl) carbodiimide based coupling chemistry was used to covalently crosslink glucose oxidase (GOx) to CS to obtain glucose sensitivity. The physicochemical properties, including chemical composition, enzyme-related characteristics, glucose responsiveness, and mechanical strength, were thoroughly investigated, followed by the cytotoxicity, antibacterial and anti-inflammatory tests. The results showed that the GOx immobilized on the film surface by covalent bonding gave better stability than those that were physically adsorbed. In addition, it could quickly and correspondingly modify its inner pore structure in response to the glucose stimulus and then control the loaded TA release. Meanwhile, the TA addition could enhance the film's mechanical properties. The composite hydrogel film demonstrated adequate biocompatibility and can inhibit NO, IL-6, and TNF-α production in stimulated macrophages, as well as Porphyromonas gingivalis growth, demonstrating effective antibacterial and anti-inflammatory activity.

Nanoparticles in Clinical Translation for Cancer Therapy

The advent of cancer therapeutics brought a paradigm shift from conventional therapy to precision medicine. The new therapeutic modalities accomplished through the properties of nanomaterials have extended their scope in cancer therapy beyond conventional drug delivery. Nanoparticles can be channeled in cancer therapy to encapsulate active pharmaceutical ingredients and deliver them to the tumor site in a more efficient manner. This review enumerates various types of nanoparticles that have entered clinical trials for cancer treatment. The obstacles in the journey of nanodrug from clinic to market are reviewed. Furthermore, the latest developments in using nanoparticles in cancer therapy are also highlighted.

Artificial exosomes mediated spatiotemporal-resolved and targeted delivery of epigenetic inhibitors

BACKGROUND

Malignant tumor is usually associated with epigenetic dysregulation, such as overexpression of histone deacetylase (HDAC), thus HDAC has emerged as a therapeutic target for cancer. Histone deacetylase inhibitor has been approved for clinical use to treat hematological cancers. However, the low solubility, short circulation lifetime, and high cytotoxicity partially limited their applications in solid tumor.

METHODS

The upconversion nanoparticles (UC) modified with mesoporous silica (SUC) was used to load an HDACI, suberoylanilide hydroxamic acid (SAHA), and further camouflaged with M1 macrophage-derived exosome membranes (EMS). EMS was characterized in size and compositions. We also analyzed the epigenetic regulation induced by EMS. Furthermore, we evaluate the biodistribution and in vivo tumor inhibition after the systemic administration of EMS.

RESULTS

This novel style spatiotemporal-resolved drug delivery system, EMS showed a high loading efficiency of SAHA. EMS could be taken up by lung cancer cells and lead to efficient epigenetic inhibition. We found that the integrin α4β1 on M1-EM, was crucial for the homing of EMS to tumor tissues for the first time. In tumor-bearing mice, EMS showed spatiotemporal-resolved properties and facilitated the drug accumulation in the tumors, which induced superior anti-tumor effects.

CONCLUSION

This novel style of spatiotemporal-resolved nanoparticles can be used as a theranostic platform for lung cancer therapy.

Molecular simulation of the diffusion mechanism of nanorods in cross-linked networks

We study the diffusion of rod-shaped nanocarriers with different rigidities and aspect ratios in cross-linked networks using coarse-grained molecular dynamics (CGMD) simulations. The diffusivity of the nanorods increases with a reduction in the rigidities of the nanorods and network, as well as with an increasing aspect ratio with respect to the same volume fraction of the nanorods. The nanorods show an anisotropic diffusion pathway through translocating along their major axes at short time scales, and the anisotropy of diffusion decreases at long time scales. Meanwhile, the diffusion of the nanorods shows a sub-diffusion regime that deviates from Brownian motion in most cases due to the trapping of the nanorods in a cage composed of the network. The nanorod could hop when it escapes from the cage and the hopping behavior depends on the rigidities of both the nanorod and network, as well as the local network density. The rotational motion of the trapped nanorod also enhances the probability of hopping. Our results may help in the understanding of the microscopic mechanism for the diffusion of rod-shaped and other relevant nanocarriers, in a cross-linked network environment.