Rapid transport of deformation-tuned nanoparticles across biological hydrogels and cellular barriers

Nanoparticle elasticity affects systemic circulation lifetime by modulating adsorption of apolipoprotein A-I in corona formation

Nanoparticle elasticity is crucial in nanoparticles' physiological fate, but how this occurs is largely unknown. Using core-shell nanoparticles with a same PEGylated lipid bilayer shell yet cores differing in elasticity (45 kPa - 760 MPa) as models, we isolate the effects of nanoparticle elasticity from those of other physiochemical parameters and, using mouse models, observe a non-monotonic relationship of systemic circulation lifetime versus nanoparticle elasticity. Incubating our nanoparticles in mouse plasma provides protein coronas varying non-monotonically in composition depending on nanoparticle elasticity. Particularly, apolipoprotein A-I (ApoA1) is the only protein whose relative abundance in corona strongly correlates with our nanoparticles' blood clearance lifetime. Notably, similar results are observed when above nanoparticles' PEGylated lipid bilayer shell is changed to be non-PEGylated. This work unveils the mechanisms by which nanoparticle elasticity affects nanoparticles' physiological fate and suggests nanoparticle elasticity as a readily tunable parameter in future rational exploiting of protein corona.

Topology mediates transport of nanoparticles in macromolecular networks

Diffusion transport of nanoparticles in confined environments of macromolecular networks is common in diverse physical systems and regulates many biological responses. Macromolecular networks possess various topologies, featured by different numbers of degrees and genera. Although the network topologies can be manipulated from a molecular level, how the topology impacts the transport of nanoparticles in macromolecular networks remains unexplored. Here, we develop theoretical approaches combined with simulations to study nanoparticle transport in a model system consisting of network cells with defined topologies. We find that the topology of network cells has a profound effect on the free energy landscape experienced by a nanoparticle in the network cells, exhibiting various scaling laws dictated by the topology. Furthermore, the examination of the impact of cell topology on the detailed behavior of nanoparticle dynamics leads to different dynamical regimes that go beyond the particulars regarding the local network loop. The results might alter the conventional picture of the physical origin of transport in networks.

Macromolecular networks relevant for biological processes and technological applications, are often characterized by complex architectures. The authors uncover the impact of topology on the properties of nanoparticle transport in macromolecular networks.

Ultrasound-Responsive Peptide Nanogels to Balance Conflicting Requirements for Deep Tumor Penetration and Prolonged Blood Circulation

A series of biological barriers need to be overcome for therapeutic nanocarriers accumulating at the tumor site and uptaken by cancer cells. One strategy is to construct switchable nanocarriers to meet the conflicting requirements for various physiology environments. In this work, besides widely studied endogenous stimuli-responsiveness, an exogenous ultrasound responsiveness was additionally embedded into nanocarriers to balance the conflicting needs of prolonged blood circulation and deep tumor penetration. Polylysine and Pluronic F127 were first coassembled and then cross-linked by genipin to form stable nanogel structure. Subsequently, ICAM-1 antibody was grafted onto the nanogel (designated as GenPLPF_T) for active tumor targeting. Upon external sonication, the F127 was shed from GenPLPF_T to induce swelling of nanogel with reduced stability and accelerated drug release. In detail, sonication leads to GenPLPF swelling from 329 to 516 nm, while its Young's modulus significantly decreased from 336.78 to 3.93 kPa. Through intravenous injection, relatively rigid GenPLPF_T was able to achieve a high level of accumulation at tumor site by active targeting and long-term blood circulation. Moreover, under sonication at the tumor site, GenPLPF_T became softer with enhanced deformability to achieve deep tumor penetration. In addition, in vivo studies revealed that GenPLPF_T was able to penetrate into the deep area of xenografted tumor with enhanced antitumor efficacy and reduced toxicity. Overall, this peptide nanogel with ultrasound-responsive stiffness demonstrates an effective approach to overcome a series of biological barriers for enhanced deep tumor therapy.

[Visualization analysis of microfluidics research status]

Microfluidics is the science and technology to manipulate small amounts of fluids in micro/nano-scale space. Multiple modules could be integrated into microfluidic device, and due to its advantages of microminiaturization and controllability, microfluidics has drawn extensive attention since its birth. In this paper, the literature data related to microfluidics research from January 1, 2006 to December 31, 2021 were obtained from Web of Science Core Collection database. CiteSpace 5.8.R3 software was used for bibliometrics analysis, so as to explore the research progress and development trends of microfluidics research at home and abroad. Based on the analysis of 50 129 articles, it could be seen that microfluidics was a hot topic of global concern, and the United States had a certain degree of authority in this field. Massachusetts Institute of Technology and Harvard University not only had a high number of publications, but also had strong influence and extensive cooperation network. Combined with ultrasonic, surface modification and sensor technology, researchers constructed paper-based microfluidic, droplet microfluidic and digital microfluidic platforms, which were applied in the field of immediate diagnosis, nucleic acid and circulating tumor cell analysis of in vitro diagnosis and organ-on-a-chip. China was one of the countries with a high level of research in the field of microfluidics, while the industrialization of high-end products needed to be improved. As people's demand for disease risk prediction and health management increased, promoting microfluidic technological innovation and achievement transformation is of great significance to safeguard people's life and health.

From Static to Dynamic: A Review on the Role of Mucus Heterogeneity in Particle and Microbial Transport

Mucus layers (McLs) are on the front line of the human defense system that protect us from foreign abiotic/biotic particles (e.g., airborne virus SARS-CoV-2) and lubricates our organs. Recently, the impact of McLs on human health (e.g., nutrient absorption and drug delivery) and diseases (e.g., infections and cancers) has been studied extensively, yet their mechanisms are still not fully understood due to their high variety among organs and individuals. We characterize these variances as the heterogeneity of McLs, which lies in the thickness, composition, and physiology, making the systematic research on the roles of McLs in human health and diseases very challenging. To advance mucosal organoids and develop effective drug delivery systems, a comprehensive understanding of McLs' heterogeneity and how it impacts mucus physiology is urgently needed. When the role of airway mucus in the penetration and transmission of coronavirus (CoV) is considered, this understanding may also enable a better explanation and prediction of the CoV's behavior. Hence, in this Review, we summarize the variances of McLs among organs, health conditions, and experimental settings as well as recent advances in experimental measurements, data analysis, and model development for simulations.

Modulation of Colloidal Particle Stiffness for the Exploration of Bio-Nano Interactions

Tuning the physicochemical parameters (e.g., size, shape, and surface chemistry) of colloidal particles (CPs) for the engineering of drug carriers has proven to be a promising approach to improve drug delivery efficacy. Recently, the stiffness of CPs has attracted widespread attention for modulating bio-nano interactions. In this perspective, we outline the strategies for the modulation and characterization of CP stiffness and highlight the importance of CP stiffness in the control over biological interactions. Challenges and opportunities of current and future developments in the modulation of CP stiffness for the exploration of bio-nano interactions in therapeutic delivery are also discussed. This perspective is expected to help thoroughly understand the role of CP stiffness in bio-nano interactions and facilitate the design of CPs as carriers for improved drug and vaccine delivery.

Lipid-Based Nanocarrier Systems for Drug Delivery: Advances and Applications

Lipid-based nanocarriers have been extensively investigated for drug delivery due to their advantages including biodegradability, biocompatibility, nontoxicity, and nonimmunogenicity. However, the shortcomings of traditional lipid-based nanocarriers such as insufficient targeting, capture by the reticuloendothelial system, and fast elimination limit the efficiency of drug delivery and therapeutic efficacy. Therefore, a series of multifunctional lipid-based nanocarriers have been developed to enhance the accumulation of drugs in the lesion site, aiming for improved diagnosis and treatment of various diseases. In this review, we summarized the advances and applications of lipid-based nanocarriers from traditional to novel functional lipid preparations, including liposomes, stimuli-responsive lipid-based nanocarriers, ionizable lipid nanoparticles, lipid hybrid nanocarriers, as well as biomembrane-camouflaged nanoparticles, and further discussed the challenges and prospects of this system. This exploration may give a complete idea viewing the lipid-based nanocarriers as a promising choice for drug delivery system, and fuel the advancement of pharmaceutical products by materials innovation and nanotechnology.

Molecular and Colloidal Transport in Bacterial Cellulose Hydrogels

Bacterial cellulose biofilms are complex networks of strong interwoven nanofibers that control transport and protect bacterial colonies in the film. The design of diverse applications of these bacterial cellulose films also relies on understanding and controlling transport through the fiber mesh, and transport simulations of the films are most accurate when guided by experimental characterization of the structures and the resultant diffusion inside. Diffusion through such films is a function of their key microstructural length scales, determining how molecules, as well as particles and microorganisms, permeate them. We use microscopy to study the unique bacterial cellulose film via its pore structure and quantify the mobility dynamics of various sizes of tracer particles and macromolecules. Mobility is hindered within the films, as confinement and local movement strongly depend on the void size relative to diffusing tracers. The biofilms have a naturally periodic structure of alternating dense and porous layers of nanofiber mesh, and we tune the magnitude of the spacing via fermentation conditions. Micron-sized particles can diffuse through the porous layers but cannot penetrate the dense layers. Tracer mobility in the porous layers is isotropic, indicating a largely random pore structure there. Molecular diffusion through the whole film is only slightly reduced by the structural tortuosity. Knowledge of transport variations within bacterial cellulose networks can be used to guide the design of symbiotic cultures in these structures and enhance their use in applications like biomedical implants, wound dressings, lab-grown meat, clothing textiles, and sensors.

Cell Membrane-Camouflaged Nanocarriers with Biomimetic Deformability of Erythrocytes for Ultralong Circulation and Enhanced Cancer Therapy

Despite considerable advancements in cell membrane-camouflaged nanocarriers to leverage natural cell functions, artificial nanocarriers that can accurately mimic both the biological and physical properties of cells are urgently needed. Herein, inspired by the important effect of the stiffness and deformability of natural red blood cells (RBCs) on their life span and flowing through narrow vessels, we report the construction of RBC membrane-camouflaged nanocarriers that can mimic RBCs at different life stages and study how the deformability of RBC-derived nanocarriers affects their biological behaviors. RBC membrane-coated elastic poly(ethylene glycol) diacrylate hydrogel nanoparticles (RBC-ENPs) simulating dynamic RBCs exhibited high immunocompatibility with minimum immunoglobulin adsorption in the surface protein corona, resulting in reduced opsonization in macrophages and ultralong circulation. Furthermore, RBC-ENPs can deform like RBCs and achieve excellent diffusion in tumor extracellular matrix, leading to improved multicellular spheroid penetration and tumor tissue accumulation. In mouse cancer models, doxorubicin-loaded RBC-ENPs demonstrated superior antitumor efficacy to the first-line chemotherapeutic drug PEGylated doxorubicin liposomes. Our work highlights that tuning the physical properties of cell membrane-derived nanocarriers may offer an alternative approach for the bionic design of nanomedicines in the future.

Static and Dynamic Biomaterial Engineering for Cell Modulation

In the biological microenvironment, cells are surrounded by an extracellular matrix (ECM), with which they dynamically interact during various biological processes. Specifically, the physical and chemical properties of the ECM work cooperatively to influence the behavior and fate of cells directly and indirectly, which invokes various physiological responses in the body. Hence, efficient strategies to modulate cellular responses for a specific purpose have become important for various scientific fields such as biology, pharmacy, and medicine. Among many approaches, the utilization of biomaterials has been studied the most because they can be meticulously engineered to mimic cellular modulatory behavior. For such careful engineering, studies on physical modulation (e.g., ECM topography, stiffness, and wettability) and chemical manipulation (e.g., composition and soluble and surface biosignals) have been actively conducted. At present, the scope of research is being shifted from static (considering only the initial environment and the effects of each element) to biomimetic dynamic (including the concepts of time and gradient) modulation in both physical and chemical manipulations. This review provides an overall perspective on how the static and dynamic biomaterials are actively engineered to modulate targeted cellular responses while highlighting the importance and advance from static modulation to biomimetic dynamic modulation for biomedical applications.

Untangling Mucosal Drug Delivery: Engineering, Designing, and Testing Nanoparticles to Overcome the Mucus Barrier

Mucus is a complex viscoelastic gel and acts as a barrier covering much of the soft tissue in the human body. High vascularization and accessibility have motivated drug delivery to various mucosal surfaces; however, these benefits are hindered by the mucus layer. To overcome the mucus barrier, many nanomedicines have been developed, with the goal of improving the efficacy and bioavailability of drug payloads. Two major nanoparticle-based strategies have emerged to facilitate mucosal drug delivery, namely, mucoadhesion and mucopenetration. Generally, mucoadhesive nanoparticles promote interactions with mucus for immobilization and sustained drug release, whereas mucopenetrating nanoparticles diffuse through the mucus and enhance drug uptake. The choice of strategy depends on many factors pertaining to the structural and compositional characteristics of the target mucus and mucosa. While there have been promising results in preclinical studies, mucus-nanoparticle interactions remain poorly understood, thus limiting effective clinical translation. This article reviews nanomedicines designed with mucoadhesive or mucopenetrating properties for mucosal delivery, explores the influence of site-dependent physiological variation among mucosal surfaces on efficacy, transport, and bioavailability, and discusses the techniques and models used to investigate mucus-nanoparticle interactions. The effects of non-homeostatic perturbations on protein corona formation, mucus composition, and nanoparticle performance are discussed in the context of mucosal delivery. The complexity of the mucosal barrier necessitates consideration of the interplay between nanoparticle design, tissue-specific differences in mucus structure and composition, and homeostatic or disease-related changes to the mucus barrier to develop effective nanomedicines for mucosal delivery.

Transition in the Glassy Dynamics of Melts of Acid-Hydrolyzed Phytoglycogen Nanoparticles

The deformability, responsiveness, and tunability of soft nanoparticles (NPs) offer unique opportunities to learn about their complex properties and the interactions between particles. In the present study, we provide new insights into the physical properties of phytoglycogen (PG) NPs, which are soft, compact particles with a dendritic architecture that are produced in the kernels of sweet corn. In particular, we study PG NPs modified using acid hydrolysis, which not only reduces their diameter but also alters their stiffness, internal structure, and the interactions between particles in aqueous dispersions. We used steady shear rheology to determine the dependence of the relative zero-shear viscosity η_r of aqueous dispersions of acid-hydrolyzed PG NPs on the effective volume fraction ϕ_eff, which indicated a reduction in stiffness of the particles relative to that of native PG NPs. We quantified this difference by analyzing the nature of the colloidal glasses formed at high ϕ_eff. We measured a smaller value of the fragility index m for acid-hydrolyzed PG NP glasses than that for native PG NP glasses, indicating that acid-hydrolyzed PG NPs form stronger glasses and are therefore softer than native PG NPs. Unlike the native PG NPs, we observed a distinctive change in the character of the glass transition of the acid-hydrolyzed PG NPs as ϕ_eff was increased above ϕ_eff∼1: a crossover in the dependence of η_r on ϕ_eff from Vogel-Fulcher-Tammann behavior to a more gradual, Arrhenius-like behavior. By expressing the steady shear and oscillatory rheology data in terms of generalized Péclet numbers, we obtained collapse of the data onto master curves. We interpret this result in terms of the acid-hydrolyzed PG NPs predominantly interpenetrating neighboring particles at large ϕ_eff, for which fluctuations of the outer chains enhance the mobility of the particles and make α-relaxation times τ_α experimentally accessible.

Size-Transformable Bicomponent Peptide Nanoparticles for Deep Tumor Penetration and Photo-Chemo Combined Antitumor Therapy

The suitable size of multifunctional nanomedicines strongly influences their physicochemical properties and actions in biological systems, for example, prolonged blood circulation time, efficient tumor accumulation, and deep tumor penetration. However, it is still a great challenge to construct size-transformable nanoparticles (NPs) for both efficient accumulation and penetration throughout tumor tissue. Herein, a size-transformed multifunctional NP is developed through a simple bicomponent assembling strategy for enhanced tumor penetration and efficient photo-chemo combined antitumor therapy, due to the acidic tumor microenvironment and near infrared-laser irradiation induced size-shrink. This multifunctional bicomponent NP (PP NP) driven by electrostatic interaction is composed of negatively charged peptide amphiphile (PA1) and positively charged peptide prodrug (PA2). PP NPs (≈170 nm) have been proven to improve blood circulation time and stability in biological environments. Interestingly, PP NPs can reassemble small NPs (<30 nm) by responding to acidic tumor microenvironment and near-infrared laser irradiation, which facilitates deep tumor penetration and improves cellular internalization. By integrating fluorescence imaging, tumor targeting, deep tumor penetration, and combined photo-chemotherapy, PP NPs exhibit excellent in vivo antitumor efficacy. This study might provide an insight for developing a bicomponent assembling system with efficient tumor penetration and multimode for antitumor therapy.

Dual-Regulated Functionalized Liposome-Nanoparticle Hybrids Loaded with Dexamethasone/TGFβ1-siRNA for Targeted Therapy of Glomerulonephritis

Mesangial cell (MC)-mediated glomerulonephritis is a frequent cause of end-stage renal disease, with immune inflammatory damage and fibrosis as its basic pathological processes. However, the treatment of glomerulonephritis remains challenging owing to limited drug accumulation and serious side effects. Hence, the specific codelivery of "anti-inflammatory/antifibrosis" drugs to the glomerular MC region is expected to yield better therapeutic effects. In this study, liposome-nanoparticle hybrids (Au-LNHy) were formed by coating the surface of gold nanoparticles with a phospholipid bilayer; the Au-LNHys formed were comodified with PEG and α8 integrin antibodies to obtain gold nanoparticle immunoliposomes (Au-ILs). Next, the Au-ILs were loaded with dexamethasone and TGFβ1 siRNA to obtain DXMS/siRNA@Au-ILs. Our results showed that the functionalized nanoparticles had a core-shell structure, a uniform and suitable particle size, low cytotoxicity, and good MC entry, and lysosomal escape abilities. The nanoparticles were found to exhibit enhanced retention in glomerular MCs due to anti-α8 integrin antibody mediation. In vivo and in vitro pharmacodynamic studies showed the enhanced efficacy of DXMS/siRNA@Au-ILs modified with α8 integrin antibodies in the treatment of glomerulonephritis. In addition, DXMS/siRNA@Au-ILs were capable of effectively reducing the expression levels of TNF-α, TGF-β1, and other cytokines, thereby improving pathological inflammatory and fibrotic conditions in the kidney, and significantly mediating the dual regulation of inflammation and fibrosis. In summary, our results demonstrated that effectively targeting the MCs of the glomerulus for drug delivery can inhibit local inflammation and fibrosis and produce better therapeutic effects, providing a new strategy and promising therapeutic approach for the development of targeted therapies for glomerular diseases.

Curvature-Mediated Pair Interactions of Soft Nanoparticles Adhered to a Cell Membrane

The curvature-mediated interactions by cell membranes are crucial in many biological processes. We systematically studied the curvature-mediated wrapping of soft nanoparticles (NPs) by a tensionless membrane and the underlying pair interactions between NPs in determining it. We found that there are three types of wrapping pathways, namely, independence, cooperation, and tubulation. The particle size, adhesion strength, and softness are found to be strongly related with the wrapping mechanism. Reducing the adhesion strength transforms the wrapping pathway from cooperation to independence, while enhancing the NP softness requires a stronger adhesion to achieve the cooperative wrapping. This transformation of the wrapping pathway is controlled by the curvature-mediated interactions between NPs. For either soft or rigid NPs, the pair interactions are repulsive at short-ranged distances between NPs, while at long-ranged distances, a larger adhesion between NPs and a membrane is needed to generate attraction between NPs. Moreover, an enhancement of NP softness weakens the repulsion between NPs. These distinct behaviors of soft NPs are ascribed to the gentler deformation of the membrane at the face-to-face region between NPs due to the flattening and spreading of soft NPs along the membrane, requiring a reduced energy cost for soft NPs to approach each other. Our results provide a mechanistic understanding in detail about the membrane-mediated interactions between NPs and their interactions with cell membranes, which is helpful to understand the curvature-mediated assemblies of adhesive proteins or NPs on membranes, and offer novel possibilities for designing an effective NP-based vehicle for controlled drug delivery.

Transmission Electron Microscopy as a Powerful Tool to Investigate the Interaction of Nanoparticles with Subcellular Structures

Nanomedical research necessarily involves the study of the interactions between nanoparticulates and the biological environment. Transmission electron microscopy has proven to be a powerful tool in providing information about nanoparticle uptake, biodistribution and relationships with cell and tissue components, thanks to its high resolution. This article aims to overview the transmission electron microscopy techniques used to explore the impact of nanoconstructs on biological systems, highlighting the functional value of ultrastructural morphology, histochemistry and microanalysis as well as their fundamental contribution to the advancement of nanomedicine.

Coordination of rigidity modulation and targeting ligand modification on orally-delivered nanoparticles for the treatment of liver fibrosis

Although the individual role of ligand modification or rigidity modulation on oral administration of nanoparticle (NP) has been investigated, how they mutually affect each other remains to be elucidated. Here, we fabricated different rigidity NP with or without surface decoration of FcBP, a neonatal Fc receptor domain-binding peptide. In vitro studies showed that, without FcBP modification, stiff NP had higher transcytosis efficiency across the epithelium than softer NP, due to the different endocytosis mechanisms, intracellular trafficking routes, and exocytosis rate. Notably, after FcBP modification, such difference was narrowed, in a manner that was more favorable for softer NP to "catch up" with stiff NP, suggesting ligand modification was more conducive to exert transcytosis-promoting efficacy on softer NP. In vivo experiments demonstrated that, for ligand-free NP, high rigidity was required for efficient oral absorption and liver distribution. Further FcBP modification decreased that "rigidity threshold", and expanded the feasible rigidity range from stiff NP to softer NP. Upon oral administration, FcBP-modified dexamethasone-loaded softer NP achieved a therapeutic efficacy comparable with stiff NP on alleviating liver fibrosis. Collectively, our study highlighted the necessity of coordinating ligand modification and rigidity modulation for oral drug delivery.

Enhanced Mucosal Transport of Polysaccharide-Calcium Phosphate Nanocomposites for Oral Vaccination

Oral vaccine has attracted much interest, as it can stimulate both mucosal and systemic immunity with noninvasive and good patient compliance. However, the oral vaccine efficiency is strongly constrained by the low absorption of antigens in the small intestine due to the mucosal barriers. Physicochemical characteristics of nanoparticles (NPs) have strong effects on antigen mucosal penetration, helping to improve immune response. However, surface functions of NPs on mucosal transportation have not been clearly understood. In this work, we elaborately investigated how the surface characteristics of mucoadhesive chitosan and its derivant act on oral antigen absorption and immune response. Core-shell chitosan- and o-carboxymethyl chitosan-coated calcium phosphate (CaP) nanocomposites have been fabricated to investigate the surface property effect on protein antigen delivery using the oral route. The interaction between polymer-coated CaP NPs and the intestinal mucosal layer was studied using mucin absorption, NP diffusion through the mucus layer, NP permeability across the epithelium monolayer, and their cellular uptake by antigen presenting cells in detail. Ex vivo mucosa distribution and in vivo oral immunization of polymer-coated CaP nanocomposites were further examined to demonstrate that the surface property of NPs affects CaP diffusion and penetration through the mucosal layer. As expected, OVA orally delivered by polymer-coated CaP nanocomposites improved the response of mucosal immunity compared to antigen OVA itself in vivo.

A common strategy to improve transmembrane transport in polarized epithelial cells based on sorting signals: Guiding nanocarriers to TGN rather than to the basolateral plasma membrane directly

The intestinal barrier has always been the rate-limiting step in the oral administration process. To overcome the intestinal barrier, researchers have widely adopted nanocarriers, especially active-targeting nanocarriers strategies. However, most of these strategies focus on the ligand decoration of nanocarriers targeting specific receptors, so their applications are confined to specific receptors or specific cell types. In this study, we tried to investigate more common strategies in the field of transmembrane transport enhancement. Trans-Golgi network (TGN) is the sorting center of biosynthetic route which could achieve polarized localization of proteins in polarized epithelial cells, and the basolateral plasma membrane is where all transcytotic cargos have to pass through. Thus, it is expected that guiding nanocarriers to TGN or basolateral plasma membrane may improve the transcytosis. Hence, we choose sorting signal peptide to modify micelles to guide micelles to TGN (named as BAC decorated micelles, BAC-M) or to basolateral plasma membrane (named as STX decorated micelles, STX-M). By incorporating coumarin-6 (C6) or Cy5-PEG-PCL in the micelles to indicate the behavior of micelles, the effects of these two strategies on the transcytosis were investigated. To our surprise, BAC-M and STX-M behaved quite differently when crossing biological barriers. BAC-M showed significant superiority in colocalization with TGN, transmembrane transport and even in vivo absorption, while STX-M had no significant difference from blank micelles. Further investigation revealed that the strategy of directly guiding nanocarriers to the basolateral plasma membrane (STX-M) only caused the stack of vesicles near the basolateral plasma membrane. So, we concluded that guiding nanocarriers to TGN which related to secretion may contribute to the transmembrane transport. This common strategy based on the physiological function of TGN in polarized epithelial cells will have broad application prospects in overcoming biological barrier.

Embracing nanomaterials' interactions with the innate immune system

Immunotherapy has firmly established itself as a compelling avenue for treating disease. Although many clinically approved immunotherapeutics engage the adaptive immune system, therapeutically targeting the innate immune system remains much less explored. Nanomedicine offers a compelling opportunity for innate immune system engagement, as many nanomaterials inherently interact with myeloid cells (e.g., monocytes, macrophages, neutrophils, and dendritic cells) or can be functionalized to target their cell-surface receptors. Here, we provide a perspective on exploiting nanomaterials for innate immune system regulation. We focus on specific nanomaterial design parameters, including size, form, rigidity, charge, and surface decoration. Furthermore, we examine the potential of high-throughput screening and machine learning, while also providing recommendations for advancing the field. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Liquid Crystal Elastomer Metamaterials with Giant Biaxial Thermal Shrinkage for Enhancing Skin Regeneration

Liquid crystal elastomers (LCEs) are a class of soft active materials of increasing interest, because of their excellent actuation and optical performances. While LCEs show biomimetic mechanical properties (e.g., elastic modulus and strength) that can be matched with those of soft biological tissues, their biointegrated applications have been rarely explored, in part, due to their high actuation temperatures (typically above 60 °C) and low biaxial actuation performances (e.g., actuation strain typically below 10%). Here, unique mechanics-guided designs and fabrication schemes of LCE metamaterials are developed that allow access to unprecedented biaxial actuation strain (-53%) and biaxial coefficient of thermal expansion (-33 125 ppm K^-1 ), significantly surpassing those (e.g., -20% and -5950 ppm K^-1 ) reported previously. A low-temperature synthesis method with use of optimized composition ratios enables LCE metamaterials to offer reasonably high actuation stresses/strains at a substantially reduced actuation temperature (46 °C). Such biocompatible LCE metamaterials are integrated with medical dressing to develop a breathable, shrinkable, hemostatic patch as a means of noninvasive treatment. In vivo animal experiments of skin repair with both round and cross-shaped wounds demonstrate advantages of the hemostatic patch over conventional strategies (e.g., medical dressing and suturing) in accelerating skin regeneration, while avoiding scar and keloid generation.

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.

Safety and Toxicity Issues of Therapeutically Used Nanoparticles from the Oral Route

The emerging science of nanotechnology sparked a research attention in its potential benefits in comparison to the conventional materials used. Oral products prepared via nanoparticles (NPs) have garnered great interest worldwide. They are used commonly to incorporate nutrients and provide antimicrobial activity. Formulation into NPs can offer opportunities for targeted drug delivery, improve drug stability in the harsh environment of the gastrointestinal (GI) tract, increase drug solubility and bioavailability, and provide sustained release in the GI tract. However, some issues like the management of toxicity and safe handling of NPs are still debated and should be well concerned before their application in oral preparations. This article will help the reader to understand safety issues of NPs in oral drug delivery and provides some recommendations to the use of NPs in the drug industry.

Stiffness of targeted layer-by-layer nanoparticles impacts elimination half-life, tumor accumulation, and tumor penetration

Nanoparticle (NP) stiffness has been shown to significantly impact circulation time and biodistribution in anticancer drug delivery. In particular, the relationship between particle stiffness and tumor accumulation and penetration in vivo is an important phenomenon to consider in optimizing NP-mediated tumor delivery. Layer-by-layer (LbL) NPs represent a promising class of multifunctional nanoscale drug delivery carriers. However, there has been no demonstration of the versatility of LbL systems in coating systems with different stiffnesses, and little is known about the potential role of LbL NP stiffness in modulating in vivo particle trafficking, although NP modulus has been recently studied for its impact on pharmacokinetics. LbL nanotechnology enables NPs to be functionalized with uniform coatings possessing molecular tumor-targeting properties, independent of the NP core stiffness. Here, we report that the stiffness of LbL NPs is directly influenced by the mechanical properties of its underlying liposomal core, enabling the modulation and optimization of LbL NP stiffness while preserving LbL NP outer layer tumor-targeting and stealth properties. We demonstrate that the stiffness of LbL NPs has a direct impact on NP pharmacokinetics, organ and tumor accumulation, and tumor penetration-with compliant LbL NPs having longer elimination half-life, higher tumor accumulation, and higher tumor penetration. Our findings underscore the importance of NP stiffness as a design parameter in enhancing the delivery of LbL NP formulations.

Tuning the Elasticity of Polymersomes for Brain Tumor Targeting

Nanoformulations show great potential for delivering drugs to treat brain tumors. However, how the mechanical properties of nanoformulations affect their ultimate brain destination is still unknown. Here, a library of membrane-crosslinked polymersomes with different elasticity are synthesized to investigate their ability to effectively target brain tumors. Crosslinked polymersomes with identical particle size, zeta potential and shape are assessed, but their elasticity is varied depending on the rigidity of incorporated crosslinkers. Benzyl and oxyethylene containing crosslinkers demonstrate higher and lower Young's modulus, respectively. Interestingly, stiff polymersomes exert superior brain tumor cell uptake, excellent in vitro blood brain barrier (BBB) and tumor penetration but relatively shorter blood circulation time than their soft counterparts. These results together affect the in vivo performance for which rigid polymersomes exerting higher brain tumor accumulation in an orthotopic glioblastoma (GBM) tumor model. The results demonstrate the crucial role of nanoformulation elasticity for brain-tumor targeting and will be useful for the design of future brain targeting drug delivery systems for the treatment of brain disease.

Advancedoral vaccine delivery strategies for improving the immunity

Infectious diseases continue to inflict a high global disease burden. The consensus is that vaccination is the most effective option against infectious diseases. Oral vaccines have unique advantages in the prevention of global pandemics due to their ease of use, high compliance, low cost, and the ability to induce both systemic and mucosal immune responses. However, challenges of adapting vaccines for oral administration remain significant. Foremost among these are enzymatic and pH-dependent degradation of antigens in the stomach and intestines, the low permeability of mucus barrier, the nonspecific uptake of antigens at the intestinal mucosal site, and the immune suppression result from the elusive immune tolerance mechanisms. Innovative delivery techniques promise great potential for improving the flexibility and efficiency of oral vaccines. A better understanding of the delivery approaches and the immunological mechanisms of oral vaccine delivery systems may provide new scientific insight and tools for developing the next-generation oral vaccine. Here, an overview of the advanced technologies in the field of oral vaccination is proposed, including mucus-penetrating nanoparticle (NP), mucoadhesive delivery vehicles, targeting antigen-presenting cell (APC) nanocarriers and enhanced paracellular delivery strategies and so on. Meanwhile, the mechanisms of delivery vectors interact with mucosal barriers are discussed.

Convenient Tuning of the Elasticity of Self-Assembled Nano-Sized Triterpenoids to Regulate Their Biological Activities

The impact of the mechanical properties of nanomedicines on their biological functions remains elusive due to the difficulty in tuning the elasticity of the vehicles without changing chemistry. Herein, we report the fabrication of elasticity-tunable self-assembled oleanolic acid (OA) nanoconstructs in an antiparallel zigzag manner and develop rigid nanoparticles (OA-NP) and flexible nanogels (OA-NG) as model systems to decipher the elasticity-biofunction relationship. OA-NG demonstrate less endocytosis and enhanced lysosome escape with deformation compared to OA-NP. Further in vitro and in vivo experiments show the active permeation of OA-NG into the interior of tumor with enhanced antitumor efficacy accompanied by decreased collagen production and eight- to tenfold immune cell infiltration. This study not only presents a facile and green strategy to develop flexible OA-NG for effective cancer treatment but also uncovers the crucial role of elasticity in regulating biological activity, which may provide reference for precise design of efficient nanomedicines.

A comprehensive parametric study for understanding the combined millifluidic and dripping encapsulation process and characterisation of oil-loaded capsules

AIM

This study aimed to utilise and optimise the millifluidic and dripping encapsulation technique to develop and characterise the oil-core capsules.

METHODS

Sodium alginate with Tween-20 (continuous phase) and sunflower oil (dispersed phase) were used in millifluidic system. After determining the surface and interfacial tensions and flow behaviour parameters, flow rates of phases and concentrations of alginate and Tween were optimised by the Taguchi method. The flow regime of droplets was also evaluated. Optimised millicapsules were characterised concerning morphology, dimension, encapsulation efficiency, SEM, FTIR and, DSC results.

RESULTS

Dripping flow regime during droplet formation was observed. Reducing the interfacial tension between the continuous and dispersed phases resulted in about a 10.18% reduction in diameter. Optimised millicapsules depicted spherical shape (0.03 ± 0.01) with 3.95 ± 0.05 mm size and 97.5 ± 0.2% encapsulation efficiency. The FTIR and DSC results confirmed the entrapment of oil.

CONCLUSION

Millifluidic and dripping method effectively encapsulated sunflower oil in core-shell capsules.

Minimally invasive co-injection of modular micro-muscular and micro-vascular tissues improves in situ skeletal muscle regeneration

Various conventional treatment strategies for volumetric muscle loss (VML) are often hampered by the extreme donor site morbidity, the limited availability of quality muscle flaps, and complicated, as well as invasive surgical procedures. The conventional biomaterial-based scaffolding systems carrying myoblasts have been extensively investigated towards improving the regeneration of the injured muscle tissues, as well as their injectable forms. However, the applicability of such designed systems has been restricted due to the lack of available vascular networks. Considering these facts, here we present the development of a unique set of two minimally invasively injectable modular microtissues, consisting of mouse myoblast (C2C12)-laden poly(lactic-co-glycolic acid) porous microspheres (PLGA PMs), or the micro-muscles, and human umbilical vein endothelial cell (HUVEC)-laden poly(ethylene glycol) hollow microrods (PEG HMs), or the microvessels. Besides systematic in vitro investigations, the myogenic performance of these modular composite microtissues, when co-injected, was explored in vivo using a mouse VML model, which confirmed improved in situ muscle regeneration and remolding. Together, we believe that the construction of these injectable modular microtissues and their combination for minimally invasive therapy provides a promising method for in situ tissue healing.

An overview of in vitro, ex vivo and in vivo models for studying the transport of drugs across intestinal barriers

Oral administration is the most commonly used route for drug delivery owing to its cost-effectiveness, ease of administration, and high patient compliance. However, the absorption of orally delivered compounds is a complex process that greatly depends on the interplay between the characteristics of the drug/formulation and the gastrointestinal tract. In this contribution, we review the different preclinical models (in vitro, ex vivo and in vivo) from their development to application for studying the transport of drugs across intestinal barriers. This review also discusses the advantages and disadvantages of each model. Furthermore, the authors have reviewed the selection and validation of these models and how the limitations of the models can be addressed in future investigations. The correlation and predictability of the intestinal transport data from the preclinical models and human data are also explored. With the increasing popularity and prevalence of orally delivered drugs/formulations, sophisticated preclinical models with higher predictive capacity for absorption of oral formulations used in clinical studies will be needed.

Identification of a potent ionizable lipid for efficient macrophage transfection and systemic anti-interleukin-1β siRNA delivery against acute liver failure

RNA interference (RNAi) therapy has great potential for treating inflammatory diseases. However, the development of potent carrier materials for delivering siRNA to macrophages is challenging. Herein, we design a set of ionizable lipid nanoparticles (LNPs) to screen and identify a potent carrier of siRNA for silencing an essential pro-inflammatory cytokine, interleukin-1β (IL-1β) in macrophages. The top performance LNP (114-LNP), containing ionizable lipid with spermine as an amine-head group, facilitated efficient siRNA internalization via multiple endocytosis pathways and achieved effective endosome escape in macrophages. The optimized LNP/siIL-1β achieved strong silencing of IL-1β in both activated Raw 264.7 cells and primary macrophages. Furthermore, systematic administration of 114-LNP/siIL-1β complexes could effectively inhibit IL-1β expression in an acute liver failure model and significantly attenuated hepatic inflammation and liver damage. These results suggest that the optimized ionizable lipid nanoparticle represents a promising platform for anti-inflammation therapies.

Drug-Rich Phases Induced by Amorphous Solid Dispersion: Arbitrary or Intentional Goal in Oral Drug Delivery?

Among many methods to mitigate the solubility limitations of drug compounds, amorphous solid dispersion (ASD) is considered to be one of the most promising strategies to enhance the dissolution and bioavailability of poorly water-soluble drugs. The enhancement of ASD in the oral absorption of drugs has been mainly attributed to the high apparent drug solubility during the dissolution. In the last decade, with the implementations of new knowledge and advanced analytical techniques, a drug-rich transient metastable phase was frequently highlighted within the supersaturation stage of the ASD dissolution. The extended drug absorption and bioavailability enhancement may be attributed to the metastability of such drug-rich phases. In this paper, we have reviewed (i) the possible theory behind the formation and stabilization of such metastable drug-rich phases, with a focus on non-classical nucleation; (ii) the additional benefits of the ASD-induced drug-rich phases for bioavailability enhancements. It is envisaged that a greater understanding of the non-classical nucleation theory and its application on the ASD design might accelerate the drug product development process in the future.

Immunostimulatory AIE Dots for Live-Cell Imaging and Drug Delivery

The mechanical properties of nanoscale drug carriers play critical roles in regulating nano-bio interactions. For example, the superior deformability of the softer nanoparticles enables them to pass through the biofilters efficiently, facilitating their long blood circulation and better tumor penetration. However, as a novel nanocarrier system, the elimination efficiency of soft nanoparticles from cells is poorly investigated. Here, we report a facile strategy to prepare soft luminescent nanoparticles through self-assembly of amphiphilic aggregation-induced emission (AIE) fluorophores. The prepared soft AIE dots exhibit strong light emission (quantum yield, ∼27.1%) and can reveal the encapsulation and excretion process of NPs in real time. The cell results showed that soft NPs can greatly increase the transfer speed of nanomaterials into cells and accelerate their elimination from cells through the sacrifice of soft AIE dots. We also show that soft AIE dots loaded with cytosine-phosphate-guanine (CpG) oligodeoxynucleotides can induce strong immunostimulatory effects, producing a high level of various proinflammatory cytokines including tumor necrosis factor (TNF)-R, interleukin (IL)-6, and IL-12. This work demonstrates a new design strategy for synthesizing a soft nanocarrier system that can deliver drugs into cells efficiently and then be eliminated from cells quickly.

Stiffness-Dependent Intracellular Location of Cylindrical Polymer Brushes

Cylindrical polymer brushes (CPBs) are macromolecules with nanoparticle proportions. Their modular synthesis enables tailoring of their chemical composition as well as the dialing-up of overall dimensions and physicochemical properties. In this study, two rod-like poly[(ethylene glycol) methyl ether methacrylate] (PEGMA)-based CPBs with varying stiffness but otherwise comparable features and functionality, are synthesized. Differences in particle stiffness are assessed using small angle neutron scattering (SANS). It is observed that the fate of the two CPBs within cells is distinctly different. Stiffer CPBs seem to gravitate toward the mitochondria, whereas CPBs with reduced stiffness are present in different intracellular vesicles.

Magnetic poly(acrylic acid)-based hydrogels for rapid ammonium sorption and efficient sorbent separation from sewage

Ammonium sorption and recovery processes typically take place in conventional packed columns, with a configuration that enables maximum sorption by the sorbents. However, batch or semi-continuous operations in packed columns have associated issues such as scaling and frequent backwashing requirements, which are economically prohibitive. As an alternative, ammonium sorption could occur in well-mixed continuously stirred tanks, which would allow for the ammonium sorption process to be retrofitted in existing wastewater treatment plants, provided that efficient sorbent separation can be achieved. This study demonstrates, for the first time, the preparation of magnetic poly(acrylic acid)-based (PAA) ammonium sorbents through the incorporation of magnetic (Fe₃O₄) nanoparticles (MNP) produced via scalable and cost-effective electrochemical synthesis. The MNP and PAA hydrogels were synthesized independently and the MNPs subsequently integrated into the PAA hydrogel network by particle diffusion and physical entrapment. No adverse effects on swelling and ammonium sorption following immersion in either synthetic or real sewage were observed after MNPs were incorporated into the hydrogels. Importantly, PAA-MNP hydrogels demonstrated high ammonium sorption efficiencies (80-93%) in real sewage and achieved rapid ammonium recovery of 73 ± 1.1% within 15 min of mild acid washing (pH 4) 15 min at a maximum recovery.

Development and characterization of gel-in-water nanoemulsion as a novel drug delivery system

The effective delivery of anti-cancer drugs with minimal side effects and better therapeutic efficacy has remained an active area of research for many decades. Organogels have gained attention in recent years as potential drug delivery systems due to their high bioavailability, no first-pass metabolism and rapid action. Considering this, in the current study an organogel based nanoemulsion was developed aiming to effectively deliver hydrophobic drugs via encapsulation within in situ gellable organogel droplets, termed as gel-in-water (G/W) nanoemulsion. G/W nanoemulsion was prepared using a combination of lipiodol and organogelator 12-hydroxystearic acid (12-HSA) as inner gel phase; dispersed in water by ultrasonication and stabilized with polyoxyethylene hydrogenated castor oil (HCO-60) as a surfactant. The prepared nanoemulsion showed high drug loading efficiency (≈97%) with a mean diameter of 206 nm. Lower polydispersity index (PdI) value (≈0.1) suggests monodispersed nature of G/W nanoemulsion in the continuous phase. G/W nanoemulsion was found stable over six months in terms of particle size, zeta potential and pH at different storage temperatures. There was no cytotoxic effect of prepared G/W nanoemulsion on primary hepatocytes in vitro. In contrast, paclitaxel-loaded G/W showed a significant decrease in melanoma cell growth (*p < 0.05) both in vitro and in vivo. Our results support the hypothesis that organogel based nanoemulsions can be a promising drug delivery system.

Stiffness-tuneable nanocarriers for controlled delivery of ASC-J9 into colorectal cancer cells

HYPOTHESIS

One of the main challenges in cancer therapy is the poor water solubility of many anticancer drugs which results in low bioavailability at the tumour sites and reduced efficacy. The currently available polymer-based anticancer drug delivery systems often suffer from low encapsulation efficiency, uncontrolled release, and lack of long-term stability. Herein, we report the development of novel stiffness-tuneable core-shell nanocarriers composed of naturally derived polymers silk fibroin (SF) and sodium alginate (SA) inside a liposomal shell for enhanced cellular uptake and controlled release of hydrophobic anticancer agent ASC-J9 (Dimethylcurcumin). It is anticipated that the stiffness of the nanocarriers has a significant effect on their cellular uptake and anticancer efficacy.

EXPERIMENTS

The nanocarriers were prepared by thin film hydration method followed by extrusion and cross-linking of SA to obtain a uniform size and shape, avoiding harsh processing conditions. The structural transformation of SF in the nanocarriers induced by SA crosslinking was determined using Fourier transform infrared (FTIR) spectroscopy. The size, zeta potential, morphology and stiffness of the nanocarriers were measured using dynamic light scattering (DLS), transmission electron microscopy (TEM) and atomic force microscopy (AFM). Drug loading and release were measured using UV-Vis spectrophotometry. The cellular uptake and anticancer efficacy of the nanocarriers were studied in HCT 116 human colorectal adenocarcinoma cells and 3D tumour spheroids using high content microscopy.

FINDINGS

The synthesized nanocarriers had high encapsulation efficiency (62-78%) and were physically stable for up to 5 months at 4 ˚C. The release profile of the drug from the nanocarriers was directed by their stiffness and was easily tuneable by changing the ratio of SF to SA in the core. Furthermore, the designed nanocarriers improved the cellular uptake and anticancer activity of ASC-J9, and enhanced its tumour penetration in HCT 116 3D colorectal cancer spheroids. These findings suggest that the designed core-shell nanocarriers can be used as a highly efficient drug delivery system for cancer therapy.

A mussel-inspired film for adhesion to wet buccal tissue and efficient buccal drug delivery

Administration of drugs via the buccal route has attracted much attention in recent years. However, developing systems with satisfactory adhesion under wet conditions and adequate drug bioavailability still remains a challenge. Here, we propose a mussel-inspired mucoadhesive film. Ex vivo models show that this film can achieve strong adhesion to wet buccal tissues (up to 38.72 ± 10.94 kPa). We also demonstrate that the adhesion mechanism of this film relies on both physical association and covalent bonding between the film and mucus. Additionally, the film with incorporated polydopamine nanoparticles shows superior advantages for transport across the mucosal barrier, with improved drug bioavailability (~3.5-fold greater than observed with oral delivery) and therapeutic efficacy in oral mucositis models (~6.0-fold improvement in wound closure at day 5 compared with that observed with no treatment). We anticipate that this platform might aid the development of tissue adhesives and inspire the design of nanoparticle-based buccal delivery systems.

Intricately structured mesoporous organosilica nanoparticles: synthesis strategies and biomedical applications

Intricately structured mesoporous organosilica nanoparticles (IMONs) are being increasingly studied from their synthesis strategies to their use in biomedical applications, because of their distinctive hierarchical structures, excellent physicochemical features and satisfactory biological properties. This minireview is the first to summarize recently developed IMONs, including yolk-shell-structured nanoparticles, multi-shelled hollow spheres, deformable nanocapsules, Janus nanostructures and virus-like bionic-structured nanocarriers, and describe the corresponding formation mechanisms and recent evolution of the strategies used to synthesize these kinds of IMONs. Structure-dependent biomedical applications, such as multidrug delivery, bioimaging, synergistic therapy and biocatalysis, are also discussed. Finally, we provide an outlook for IMONs ranging from their structural control to synthesis strategies and ending with their use in biomedical applications.

Low nanogel stiffness favors nanogel transcytosis across an in vitro blood-brain barrier

Transport of therapeutics across the blood-brain barrier (BBB) is a fundamental requirement for effective treatment of numerous brain diseases. However, most therapeutics (>500 Da) are unable to permeate through the BBB and do not achieve therapeutic doses. Nanoparticles (NPs) are being investigated to facilitate drug delivery to the brain. Here, we investigate the effect of nanoparticle stiffness on NP transport across an in vitro BBB model. To this end, fluorescently labeled poly(N-isopropylmethacrylamide) (p(NIPMAM)) nanogels' stiffness was varied by the inclusion of 1.5 mol% (NG1.5), 5 mol% (NG5), and 14 mol% (NG14) N,N'-methylenebis(acrylamide) (BIS) cross-linker and nanogel uptake and transcytosis was quantified. The more densely cross-linked p(NIPMAM) nanogels showed the highest level of uptake by polarized brain endothelial cells, whereas the less densely cross-linked nanogels demonstrated the highest transcytotic potential. These findings suggest that nanogel stiffness has opposing effects on nanogel uptake and transcytosis at the BBB.

Photo-controlled degradation of PLGA/Ti3C2 hybrid coating on Mg-Sr alloy using near infrared light

A PLGA/Ti3C2 hybrid coating was successfully deposited on the surface of magnesium-strontium (Mg-Sr) alloys. Compared with the corrosion current density (i corr ) of the Mg-Sr alloy (7.13 × 10-5 A/cm2), the modified samples (Mg/PLGA/Ti3C2) was lower by approximately four orders of magnitude (7.65 × 10-9 A/cm2). After near infrared 808 nm laser irradiation, the i corr of the modified samples increased to 3.48 × 10-7 A/cm2. The mechanism is that the local hyperthermia induced the free volume expansion of PLGA, and the increase in intermolecular gap enhanced the penetration of electrolytes. Meanwhile, the cytotoxicity study showed that the hybrid coating endowed the Mg-Sr alloy with enhanced biocompatibility.

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

The poor understanding of the complex multistep process taken by nanocarriers during the delivery process limits the delivery efficiencies and further hinders the translation of these systems into medicine. Here, we describe a series of six self-assembled nanocarrier types with systematically altered physical properties including size, shape, and rigidity, as well as both in vitro and in vivo analyses of their performance in blood circulation, tumor penetration, cancer cell uptake, and anticancer efficacy. We also developed both data and simulation-based models for understanding the influence of physical properties, both individually and considered together, on each delivery step and overall delivery process. Thus, beyond finding that nanocarriers that are simultaneously endowed with tubular shape, short length, and low rigidity outperformed the other types, we now have a suit of theoretical models that can predict how nanocarrier properties will individually and collectively perform in the multistep delivery of anticancer therapies.

Biomimetic inorganic-organic hybrid nanoparticles from magnesium-substituted amorphous calcium phosphate clusters and polyacrylic acid molecules

Amorphous calcium phosphate (ACP) has been widely found during bone and tooth biomineralization, but the meta-stability and labile nature limit further biomedical applications. The present study found that the chelation of polyacrylic acid (PAA) molecules with Ca²⁺ ions in Mg-ACP clusters (~2.1 ± 0.5 nm) using a biomineralization strategy produced inorganic-organic Mg-ACP/PAA hybrid nanoparticles with better thermal stability. Mg-ACP/PAA hybrid nanoparticles (~24.0 ± 4.8 nm) were pH-responsive and could be efficiently digested under weak acidic conditions (pH 5.0–5.5). The internalization of assembled Mg-ACP/PAA nanoparticles by MC3T3-E1 cells occurred through endocytosis, indicated by laser scanning confocal microscopy and cryo-soft X-ray tomography. Our results showed that cellular lipid membranes remained intact without pore formation after Mg-ACP/PAA particle penetration. The assembled Mg-ACP/PAA particles could be digested in cell lysosomes within 24 h under weak acidic conditions, thereby indicating the potential to efficiently deliver encapsulated functional molecules. Both the in vitro and in vivo results preliminarily demonstrated good biosafety of the inorganic-organic Mg-ACP/PAA hybrid nanoparticles, which may have potential for biomedical applications.

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Mg-ACP/PAA hybrid nanoparticles have been synthesized following a biomineralization strategy.

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The chelation of PAA molecules in synergy with Mg²⁺ substitution improves thermal stability of Mg-ACP/PAA nanoparticles.

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The Mg-ACP/PAA nanoparticles are pH sensitive and can be digested in cell lysosomes within 24 h.