The effect of particle size on the biodistribution of low-modulus hydrogel PRINT particles

Artificial cells for in vivo biomedical applications through red blood cell biomimicry

Recent research in artificial cell production holds promise for the development of delivery agents with therapeutic effects akin to real cells. To succeed in these applications, these systems need to survive the circulatory conditions. In this review we present strategies that, inspired by the endurance of red blood cells, have enhanced the viability of large, cell-like vehicles for in vivo therapeutic use, particularly focusing on giant unilamellar vesicles. Insights from red blood cells can guide modifications that could transform these platforms into advanced drug delivery vehicles, showcasing biomimicry's potential in shaping the future of therapeutic applications.

Preclinical characterization of macrophage-adhering gadolinium micropatches for MRI contrast after traumatic brain injury in pigs

The choroid plexus (ChP) of the brain plays a central role in orchestrating the recruitment of peripheral leukocytes into the central nervous system (CNS) through the blood-cerebrospinal fluid (BCSF) barrier in pathological conditions, thus offering a unique niche to diagnose CNS disorders. We explored whether magnetic resonance imaging of the ChP could be optimized for mild traumatic brain injury (mTBI). mTBI induces subtle, yet influential, changes in the brain and is currently severely underdiagnosed. We hypothesized that mTBI induces sufficient alterations in the ChP to cause infiltration of circulating leukocytes through the BCSF barrier and developed macrophage-adhering gadolinium [Gd(III)]-loaded anisotropic micropatches (GLAMs), specifically designed to image infiltrating immune cells. GLAMs are hydrogel-based discoidal microparticles that adhere to macrophages without phagocytosis. We present a fabrication process to prepare GLAMs at scale and demonstrate their loading with Gd(III) at high relaxivities, a key indicator of their effectiveness in enhancing image contrast and clarity in medical imaging. In vitro experiments with primary murine and porcine macrophages demonstrated that GLAMs adhere to macrophages also under shear stress and did not affect macrophage viability or functions. Studies in a porcine mTBI model confirmed that intravenously administered macrophage-adhering GLAMs provide a differential signal in the ChP and lateral ventricles at Gd(III) doses 500- to 1000-fold lower than those used in the current clinical standard Gadavist. Under the same mTBI conditions, Gadavist did not offer a differential signal at clinically used doses. Our results suggest that macrophage-adhering GLAMs could facilitate mTBI diagnosis.

Template-Free Manufacturing of Defined Structure and Size Polymeric Microparticles

Complex-structured polymeric microparticles hold significant promise as an advance in next-generation medicine mostly due to demand from developing targeted drug delivery. However, the conventional methods for producing these microparticles of defined size, shape, and sophisticated composition often face challenges in scalability, reliance on specialized components such as micro-patterned templates, or limited control over particle size distribution and cargo (functional payload) release kinetics. In this study, we introduce a novel and reliably scalable approach for manufacturing microparticles of defined structures and sizes with variable parameters. The concept behind this method involves the deposition of a specific number of polymer layers on a substrate with low surface energy. Each layer can serve as either the carrier for cargo or a programmable shell-former with predefined permeability. Subsequently, this layered structure is precisely cut into desired-size blanks (particle precursors) using a laser. The manufacturing process is completed by applying heat to the substrate, which results in sealing the edges of the blanks. The combination of the high surface tension of the molten polymer and the low surface energy of the substrate enables the formation of discrete particles, each possessing semi-spherical or other designed geometries determined by their internal composition. Such anisotropic microparticles are envisaged to have versatile applications.

Tailored mechanosensitive nanogels release drugs upon exposure to different levels of stenosis

Owing to the unhealthy lifestyle and genetic susceptibility of today's population, atherosclerosis is one of the global leading causes of life-threatening cardiovascular diseases. Although a rapid intervention is required for severe blood vessel constrictions, a systemic administration of anticoagulant drugs is not the preferred method of choice as the associated risk of bleeding complications is high. In this study, we present mechanosensitive nanogels that exhibit tunable degrees of disintegration upon exposure to different levels of stenosis. Those nanogels can be further functionalized to encapsulate charged drug molecules such as heparin, and they efficiently release their cargo when passing stenotic constrictions; however, passive drug leakage in the absence of mechanical shear stress is very low. Furthermore, heparin molecules liberated from those mechanosensitive nanogels show a similar blood clot lysis efficiency as the free drug molecules, which demonstrates that drug encapsulation into those nanogels does not interfere with the functionality of the cargo. Thus, the hemocompatible and mechanoresponsive nanogels developed here represent a smart and efficient drug delivery platform that can offer safer solutions for vascular therapy.

Leveraging the therapeutic, biological, and self-assembling potential of peptides for the treatment of viral infections

Peptides and peptide-based materials have an increasing role in the treatment of viral infections through their use as active pharmaceutical ingredients, targeting moieties, excipients, carriers, or structural components in drug delivery systems. The discovery of peptide-based therapeutic compounds, coupled with the development of new stabilization and formulation strategies, has led to a resurgence of antiviral peptide therapeutics over the past two decades. The ability of peptides to bind cell receptors and to facilitate membrane penetration and subsequent intracellular trafficking enables their use in various antiviral systems for improved targeting efficiency and treatment efficacy. Importantly, the self-assembly of peptides into well-defined nanostructures provides a vast library of discrete constructs and supramolecular biomaterials for systemic and local delivery of antiviral agents. We review here the recent progress in exploiting the therapeutic, biological, and self-assembling potential of peptides, peptide conjugates, and their supramolecular assemblies in treating human viral infections, with an emphasis on the treatment strategies for Human Immunodeficiency Virus (HIV).

Targeting vascular inflammation through emerging methods and drug carriers

Acute inflammation is a common dangerous component of pathogenesis of many prevalent conditions with high morbidity and mortality including sepsis, thrombosis, acute respiratory distress syndrome (ARDS), COVID-19, myocardial and cerebral ischemia-reperfusion, infection, and trauma. Inflammatory changes of the vasculature and blood mediate the course and outcome of the pathology in the tissue site of insult, remote organs and systemically. Endothelial cells lining the luminal surface of the vasculature play the key regulatory functions in the body, distinct under normal vs. pathological conditions. In theory, pharmacological interventions in the endothelial cells might enable therapeutic correction of the overzealous damaging pro-inflammatory and pro-thrombotic changes in the vasculature. However, current agents and drug delivery systems (DDS) have inadequate pharmacokinetics and lack the spatiotemporal precision of vascular delivery in the context of acute inflammation. To attain this level of precision, many groups design DDS targeted to specific endothelial surface determinants. These DDS are able to provide specificity for desired tissues, organs, cells, and sub-cellular compartments needed for a particular intervention. We provide a brief overview of endothelial determinants, design of DDS targeted to these molecules, their performance in experimental models with focus on animal studies and appraisal of emerging new approaches. Particular attention is paid to challenges and perspectives of targeted therapeutics and nanomedicine for advanced management of acute inflammation.

Minibeam radiation therapy enhanced tumor delivery of PEGylated liposomal doxorubicin in a triple-negative breast cancer mouse model

BACKGROUND

Minibeam radiation therapy is an experimental radiation therapy utilizing an array of parallel submillimeter planar X-ray beams. In preclinical studies, minibeam radiation therapy has been shown to eradicate tumors and cause significantly less damage to normal tissue compared to equivalent radiation doses delivered by conventional broadbeam radiation therapy, where radiation dose is uniformly distributed.

METHODS

Expanding on prior studies that suggested minibeam radiation therapy increased perfusion in tumors, we compared a single fraction of minibeam radiation therapy (peak dose:valley dose of 28 Gy:2.1 Gy and 100 Gy:7.5 Gy) and broadbeam radiation therapy (7 Gy) in their ability to enhance tumor delivery of PEGylated liposomal doxorubicin and alter the tumor microenvironment in a murine tumor model. Plasma and tumor pharmacokinetic studies of PEGylated liposomal doxorubicin and tumor microenvironment profiling were performed in a genetically engineered mouse model of claudin-low triple-negative breast cancer (T11).

RESULTS

Minibeam radiation therapy (28 Gy) and broadbeam radiation therapy (7 Gy) increased PEGylated liposomal doxorubicin tumor delivery by 7.1-fold and 2.7-fold, respectively, compared to PEGylated liposomal doxorubicin alone, without altering the plasma disposition. The enhanced tumor delivery of PEGylated liposomal doxorubicin by minibeam radiation therapy is consistent after repeated dosing, is associated with changes in tumor macrophages but not collagen or angiogenesis, and nontoxic to local tissues. Our study indicated that the minibeam radiation therapy's ability to enhance the drug delivery decreases from 28 to 100 Gy peak dose.

DISCUSSION

Our studies suggest that low-dose minibeam radiation therapy is a safe and effective method to significantly enhance the tumor delivery of nanoparticle agents.

Anisotropic Particles through Multilayer Assembly

The anisotropy in the shape of polymeric particles has been demonstrated to have many advantages over spherical particulates, including bio-mimetic behavior, shaped-directed flow, deformation, surface adhesion, targeting, motion, and permeability. The layer-by-layer (LbL) assembly is uniquely suited for synthesizing anisotropic particles as this method allows for simple and versatile replication of diverse colloid geometries with precise control over their chemical and physical properties. This review highlights recent progress in anisotropic particles of micrometer and nanometer sizes produced by a templated multilayer assembly of synthetic and biological macromolecules. Synthetic approaches to produce capsules and hydrogels utilizing anisotropic templates such as biological, polymeric, bulk hydrogel, inorganic colloids, and metal-organic framework crystals as sacrificial templates are overviewed. Structure-property relationships controlled by the anisotropy in particle shape and surface are discussed and compared with their spherical counterparts. Advances and challenges in controlling particle properties through varying shape anisotropy and surface asymmetry are outlined. The perspective applications of anisotropic colloids in biomedicine, including programmed behavior in the blood and tissues as artificial cells, nano-motors/sensors, and intelligent drug carriers are also discussed.

Fucoidan-functionalized polysaccharide submicroparticles loaded with alteplase for efficient targeted thrombolytic therapy

Intravenous administration of fibrinolytic drugs is the standard treatment of acute thrombotic diseases. However, current fibrinolytics exhibit limited clinical efficacy because of their short plasma half-lives and might trigger hemorrhagic transformations. Therefore, it is mandatory to develop innovative nanomedicine-based solutions for more efficient and safer thrombolysis with biocompatible and biodegradable thrombus-targeted nanocarrier. Herein, fucoidan-functionalized hydrogel polysaccharide submicroparticles with high biocompatibility are elaborated by the inverse miniemulsion/crosslinking method. They are loaded with the gold standard fibrinolytic - alteplase - to direct site-specific fibrinolysis due to nanomolar interactions between fucoidan and P-selectin overexpressed on activated platelets and endothelial cells in the thrombus area. The thrombus targeting properties of these particles are validated in a microfluidic assay containing recombinant P-selectin and activated platelets under arterial and venous blood shear rates as well as in vivo. The experiments on the murine model of acute thromboembolic ischemic stroke support this product's therapeutic efficacy, revealing a faster recanalization rate in the middle cerebral artery than with free alteplase, which reduces post-ischemic cerebral infarct lesions and blood-brain barrier permeability. Altogether, this proof-of-concept study demonstrates the potential of a biomaterial-based targeted nanomedicine for the precise treatment of acute thrombotic events, such as ischemic stroke.

PEG-modified gadolinium nanoparticles as contrast agents for in vivo micro-CT

Vascular research is largely performed in rodents with the goal of developing treatments for human disease. Micro-computed tomography (micro-CT) provides non-destructive three-dimensional imaging that can be used to study the vasculature of rodents. However, to distinguish vasculature from other soft tissues, long-circulating contrast agents are required. In this study, we demonstrated that poly(ethylene glycol) (PEG)-coated gadolinium nanoparticles can be used as a vascular contrast agent in micro-CT. The coated particles could be lyophilized and then redispersed in an aqueous solution to achieve 100 mg/mL of gadolinium. After an intravenous injection of the contrast agent into mice, micro-CT scans showed blood pool contrast enhancements of at least 200 HU for 30 min. Imaging and quantitative analysis of gadolinium in tissues showed the presence of contrast agent in clearance organs including the liver and spleen and very low amounts in other organs. In vitro cell culture experiments, subcutaneous injections, and analysis of mouse body weight suggested that the agents exhibited low toxicity. Histological analysis of tissues 5 days after injection of the contrast agent showed cytotoxicity in the spleen, but no abnormalities were observed in the liver, lungs, kidneys, and bladder.

Thermostability, Tunability, and Tenacity of RNA as Rubbery Anionic Polymeric Materials in Nanotechnology and Nanomedicine-Specific Cancer Targeting with Undetectable Toxicity

RNA nanotechnology is the bottom-up self-assembly of nanometer-scale architectures, resembling LEGOs, composed mainly of RNA. The ideal building material should be (1) versatile and controllable in shape and stoichiometry, (2) spontaneously self-assemble, and (3) thermodynamically, chemically, and enzymatically stable with a long shelf life. RNA building blocks exhibit each of the above. RNA is a polynucleic acid, making it a polymer, and its negative-charge prevents nonspecific binding to negatively charged cell membranes. The thermostability makes it suitable for logic gates, resistive memory, sensor set-ups, and NEM devices. RNA can be designed and manipulated with a level of simplicity of DNA while displaying versatile structure and enzyme activity of proteins. RNA can fold into single-stranded loops or bulges to serve as mounting dovetails for intermolecular or domain interactions without external linking dowels. RNA nanoparticles display rubber- and amoeba-like properties and are stretchable and shrinkable through multiple repeats, leading to enhanced tumor targeting and fast renal excretion to reduce toxicities. It was predicted in 2014 that RNA would be the third milestone in pharmaceutical drug development. The recent approval of several RNA drugs and COVID-19 mRNA vaccines by FDA suggests that this milestone is being realized. Here, we review the unique properties of RNA nanotechnology, summarize its recent advancements, describe its distinct attributes inside or outside the body and discuss potential applications in nanotechnology, medicine, and material science.

Use of Protamine in Nanopharmaceuticals-A Review

Macromolecular biomolecules are currently dethroning classical small molecule therapeutics because of their improved targeting and delivery properties. Protamine-a small polycationic peptide-represents a promising candidate. In nature, it binds and protects DNA against degradation during spermatogenesis due to electrostatic interactions between the negatively charged DNA-phosphate backbone and the positively charged protamine. Researchers are mimicking this technique to develop innovative nanopharmaceutical drug delivery systems, incorporating protamine as a carrier for biologically active components such as DNA or RNA. The first part of this review highlights ongoing investigations in the field of protamine-associated nanotechnology, discussing the self-assembling manufacturing process and nanoparticle engineering. Immune-modulating properties of protamine are those that lead to the second key part, which is protamine in novel vaccine technologies. Protamine-based RNA delivery systems in vaccines (some belong to the new class of mRNA-vaccines) against infectious disease and their use in cancer treatment are reviewed, and we provide an update on the current state of latest developments with protamine as pharmaceutical excipient for vaccines.

Deformable microparticles for shuttling nanoparticles to the vascular wall

Vascular-targeted drug carriers must localize to the wall (i.e., marginate) and adhere to a diseased endothelium to achieve clinical utility. The particle size has been reported as a critical physical property prescribing particle margination in vitro and in vivo blood flows. Different transport process steps yield conflicting requirements-microparticles are optimal for margination, but nanoparticles are better for intracellular or tissue delivery. Here, we evaluate deformable hydrogel microparticles as carriers for transporting nanoparticles to a diseased vascular wall. Depending on microparticle modulus, nanoparticle-loaded poly(ethylene glycol)-based hydrogel microparticles delivered significantly more 50-nm nanoparticles to the vessel wall than freely injected nanoparticles alone, resulting in >3000% delivery increase. This work demonstrates the benefit of optimizing microparticles' efficient margination to enhance nanocarriers' transport to the vascular wall.

Influence of nanomedicine mechanical properties on tumor targeting delivery

Modulating nanomedicine mechanical properties for enhanced drug delivery to tumors has attracted increasing attention in the past few decades. In this tutorial review, we analyze the impact of nanomedicine mechanical properties on in vivo transport processes and highlight the most recent advances in drug delivery efficiency and antitumor efficacy. Typical nanoparticles that have been explored for this purpose since 2000 are summarized while the methods to tune and the techniques to characterize nanomedicine mechanical properties are introduced. In the end, challenges and perspectives on tailoring nanomedicine mechanical properties for tumor targeting delivery are discussed.

Challenges and opportunities in the delivery of cancer therapeutics: update on recent progress

Global cancer prevalence has continuously increased in the last decades despite substantial progress achieved for patient care. Cancer is no longer recognized as a singular disease but as a plurality of different ones, leading to the important choice of the drug administration route and promoting the development of novel drug-delivery systems (DDS). Due to their structural diversity, therapeutic cancer drugs present specific challenges in physicochemical properties that can adversely affect their efficacy and toxicity profile. These challenges are addressed by innovative DDS to improve bioavailability, pharmacokinetics and biodistribution profiles. Here, we define the drug delivery challenges related to oral, intravenous, subcutaneous or alternative routes of administration, and review innovative DDS, marketed or in development, that answer those challenges.

Intertwined mechanisms define transport of anti-ICAM nanocarriers across the endothelium and brain delivery of a therapeutic enzyme

The interaction of drug delivery systems with tissues is key for their application. An example is drug carriers targeted to endothelial barriers, which can be transported to intra-endothelial compartments (lysosomes) or transcellularly released at the tissue side (transcytosis). Although carrier targeting valency influences this process, the mechanism is unknown. We studied this using polymer nanocarriers (NCs) targeted to intercellular adhesion molecule-1 (ICAM-1), an endothelial-surface glycoprotein whose expression is increased in pathologies characterized by inflammation. A bell-shaped relationship was found between NC targeting valency and the rate of transcytosis, where high and low NC valencies rendered less efficient transcytosis rates than an intermediate valency formulation. In contrast, an inverted bell-shape relationship was found for NC valency and lysosomal trafficking rates. Data suggested a model where NC valency plays an opposing role in the two sub-processes involved in transcytosis: NC binding-uptake depended directly on valency and exocytosis-detachment was inversely related to this parameter. This is because the greater the avidity of the NC-receptor interaction the more efficient uptake becomes, but NC-receptor detachment post-transport is more compromised. Cleavage of the receptor at the basolateral side of endothelial cells facilitated NC transcytosis, likely by helping NC detachment post-transport. Since transcytosis encompasses both sets of events, the full process finds an optimum at the intersection of these inverted relationships, explaining the bell-shaped behavior. NCs also trafficked to lysosomes from the apical side and, additionally, from the basolateral side in the case of high valency NCs which are slower at detaching from the receptor. This explains the opposite behavior of NC valency for transcytosis vs. lysosomal transport. Anti-ICAM NCs were verified to traffic into the brain after intravenous injection in mice, and both cellular and in vivo data showed that intermediate valency NCs resulted in higher delivery of a therapeutic enzyme, acid sphingomyelinase, required for types A and B Niemann-Pick disease.

Biomimetic cellular vectors for enhancing drug delivery to the lungs

Despite recent advances in drug delivery, the targeted treatment of unhealthy cells or tissues continues to remain a priority. In cancer (much like other pathologies), delivery vectors are designed to exploit physical and biological features of unhealthy tissues that are not always homogenous across the disease. In some cases, shifting the target from unhealthy tissues to the whole organ can represent an advantage. Specifically, the natural organ-specific retention of nanotherapeutics following intravenous administration as seen in the lung, liver, and spleen can be strategically exploited to enhance drug delivery. Herein, we outline the development of a cell-based delivery system using macrophages as a delivery vehicle. When loaded with a chemotherapeutic payload (i.e., doxorubicin), these cellular vectors (CELVEC) were shown to provide continued release within the lung. This study provides proof-of-concept evidence of an alternative class of biomimetic delivery vectors that capitalize on cell size to provide therapeutic advantages for pulmonary treatments.

Hydrogel microparticles for biomedical applications

Hydrogel microparticles (HMPs) are promising for biomedical applications, ranging from the therapeutic delivery of cells and drugs to the production of scaffolds for tissue repair and bioinks for 3D printing. Biologics (cells and drugs) can be encapsulated into HMPs of predefined shapes and sizes using a variety of fabrication techniques (batch emulsion, microfluidics, lithography, electrohydrodynamic (EHD) spraying and mechanical fragmentation). HMPs can be formulated in suspensions to deliver therapeutics, as aggregates of particles (granular hydrogels) to form microporous scaffolds that promote cell infiltration or embedded within a bulk hydrogel to obtain multiscale behaviours. HMP suspensions and granular hydrogels can be injected for minimally invasive delivery of biologics, and they exhibit modular properties when comprised of mixtures of distinct HMP populations. In this Review, we discuss the fabrication techniques that are available for fabricating HMPs, as well as the multiscale behaviours of HMP systems and their functional properties, highlighting their advantages over traditional bulk hydrogels. Furthermore, we discuss applications of HMPs in the fields of cell delivery, drug delivery, scaffold design and biofabrication.

Nonspherical Nanoparticle Shape Stability Is Affected by Complex Manufacturing Aspects: Its Implications for Drug Delivery and Targeting

The shape of nanoparticles is known recently as an important design parameter influencing considerably the fate of nanoparticles with and in biological systems. Several manufacturing techniques to generate nonspherical nanoparticles as well as studies on in vitro and in vivo effects thereof have been described. However, nonspherical nanoparticle shape stability in physiological-related conditions and the impact of formulation parameters on nonspherical nanoparticle resistance still need to be investigated. To address these issues, different nanoparticle fabrication methods using biodegradable polymers are explored to produce nonspherical nanoparticles via the prevailing film-stretching method. In addition, systematic comparisons to other nanoparticle systems prepared by different manufacturing techniques and less biodegradable materials (but still commonly utilized for drug delivery and targeting) are conducted. The study evinces that the strong interplay from multiple nanoparticle properties (i.e., internal structure, Young's modulus, surface roughness, liquefaction temperature [glass transition (T_g ) or melting (T_m )], porosity, and surface hydrophobicity) is present. It is not possible to predict the nonsphericity longevity by merely one or two factor(s). The most influential features in preserving the nonsphericity of nanoparticles are existence of internal structure and low surface hydrophobicity (i.e., surface-free energy (SFE) > ≈55 mN m^-1 , material-water interfacial tension <6 mN m^-1 ), especially if the nanoparticles are soft (<1 GPa), rough (R_rms > 10 nm), porous (>1 m² g^-1 ), and in possession of low bulk liquefaction temperature (<100 °C). Interestingly, low surface hydrophobicity of nanoparticles can be obtained indirectly by the significant presence of residual stabilizers. Therefore, it is strongly suggested that nonsphericity of particle systems is highly dependent on surface chemistry but cannot be appraised separately from other factors. These results and reviews allot valuable guidelines for the design and manufacturing of nonspherical nanoparticles having adequate shape stability, thereby appropriate with their usage purposes. Furthermore, they can assist in understanding and explaining the possible mechanisms of nonspherical nanoparticles effectivity loss and distinctive material behavior at the nanoscale.

Hydrogels: soft matters in photomedicine

Photodynamic therapy (PDT), a shining beacon in the realm of photomedicine, is a non-invasive technique that utilizes dye-based photosensitizers (PSs) in conjunction with light and oxygen to produce reactive oxygen species to combat malignant tissues and infectious microorganisms. Yet, for PDT to become a common, routine therapy, it is still necessary to overcome limitations such as photosensitizer solubility, long-term side effects (e.g., photosensitivity) and to develop safe, biocompatible and target-specific formulations. Polymer based drug delivery platforms are an effective strategy for the delivery of PSs for PDT applications. Among them, hydrogels and 3D polymer scaffolds with the ability to swell in aqueous media have been deeply investigated. Particularly, hydrogel-based formulations present real potential to fulfill all requirements of an ideal PDT platform by overcoming the solubility issues, while improving the selectivity and targeting drawbacks of the PSs alone. In this perspective, we summarize the use of hydrogels as carrier systems of PSs to enhance the effectiveness of PDT against infections and cancer. Their potential in environmental and biomedical applications, such as tissue engineering photoremediation and photochemistry, is also discussed.

Shape Recovery of Spherical Hydrogen-Bonded Multilayer Capsules after Osmotically Induced Deformation

The mechanical properties of microparticles intended for in vivo applications as drug delivery vehicles are among important parameters that influence their circulation in the blood and govern particle biodistribution. We report on the synthesis of soft but mechanically robust spherical capsules via a hydrogen-bonded multilayer assembly of (poly(N-vinylpyrrolidone), M_w = 10 000 g mol^-1) with (poly(methacrylic acid) M_w = 100 000 g mol^-1)) (PVPON/PMAA)_n in methanol using 4 μm nonporous silica microparticles as sacrificial templates, where n = 5 and 10 and represents the bilayer number. The mechanical properties of (PVPON/PMAA)_n spherical capsules were assessed using the osmotic pressure difference method and resulted in an elasticity modulus of 97 ± 8 MPa, which is in the range of Young's modulus for elastomeric networks. We also found that hydrogen-bonded (PVPON/PMAA)₁₀ capsules demonstrated almost complete recovery from a concave buckled inward shape induced by the osmotic pressure difference from the addition of polystyrene sulfonate (PSS) to the capsule solution to their initial spherical shape within 12 h after the PSS solution was rinsed off. The permeability measurements through the capsule shell using fluorescently labeled dextran molecular probes revealed that the average mesh size of the hydrogen-bonded network assembled in methanol is in the range of 3 to 9 nm and is not permeable to FITC-dextran with a molecular weight of >40 000 g mol^-1. Our study shows that physically cross-linked polyelectrolyte multilayer capsules are capable of withstanding large deformations, which is essential to the development of adaptable particles for controlled delivery.

Size Dependency of Circulation and Biodistribution of Biomimetic Nanoparticles: Red Blood Cell Membrane-Coated Nanoparticles

Recently, biomimetic nanoparticles, especially cell membrane-cloaked nanoparticles, have attracted increasing attention in biomedical applications, including antitumor therapy, detoxification, and immune modulation, by imitating the structure and the function of biological systems such as long circulation life in the blood. However, the circulation time of cell membrane-cloaked nanoparticles is far less than that of the original cells, greatly limiting their biomedical applications, while the underlying reasons are seldom demonstrated. In this study, the influence of particle size on the circulation and the biodistribution of red blood cell membrane-coated nanoparticles (RBC-NPs) as model biomimetic nanoparticles were investigated. Differently sized RBC-NPs (80, 120, 160, and 200 nm) were prepared by fusing RBC membranes on poly(lactic-co-glycolic acid) nanoparticles. It was shown that the particle size did not change the cellular uptake of these biomimetic nanoparticles by macrophage cells in vitro and their immunogenic responses in vivo. However, their circulation life in vivo decreased with the particle size, while their accumulation in the liver increased with the particle size, which might be related to their size-dependent filtration through hepatic sinusoids. These findings will provide experimental evidence for the design and the optimization of biomimetic nanoparticles.

Nanoformulation properties, characterization, and behavior in complex biological matrices: Challenges and opportunities for brain-targeted drug delivery applications and enhanced translational potential

Nanocarriers (synthetic/cell-based have attracted enormous interest for various therapeutic indications, including neurodegenerative disorders. A broader understanding of the impact of nanomedicines design is now required to enhance their translational potential. Nanoformulations in vivo journey is significantly affected by their physicochemical properties including the size, shape, hydrophobicity, elasticity, and surface charge/chemistry/morphology, which play a role as an interface with the biological environment. Understanding protein corona formation is crucial in characterizing nanocarriers and evaluating their interactions with biological systems. In this review, the types and properties of the brain-targeted nanocarriers are discussed. The biological factors and nanocarriers properties affecting their in vivo behavior are elaborated. The compositional description of cell culture and biological matrices, including proteins potentially relevant to protein corona built-up on nanoformulation especially for brain administration, is provided. Analytical techniques of characterizing nanocarriers in complex matrices, their advantages, limitations, and implementation challenges in industrial GMP environment are discussed. The uses of orthogonal complementary characterization approaches of nanocarriers are also covered.

δ-Tocopherol Effect on Endocytosis and Its Combination with Enzyme Replacement Therapy for Lysosomal Disorders: A New Type of Drug Interaction?

Induction of lysosomal exocytosis alleviates lysosomal storage of undigested metabolites in cell models of lysosomal disorders (LDs). However, whether this strategy affects other vesicular compartments, e.g., those involved in endocytosis, is unknown. This is important both to predict side effects and to use this strategy in combination with therapies that require endocytosis for intracellular delivery, such as lysosomal enzyme replacement therapy (ERT). We investigated this using δ-tocopherol as a model previously shown to induce lysosomal exocytosis and cell models of type A Niemann-Pick disease, a LD characterized by acid sphingomyelinase (ASM) deficiency and sphingomyelin storage. δ-Tocopherol and derivative CF3-T reduced net accumulation of fluid phase, ligands, and polymer particles via phagocytic, caveolae-, clathrin-, and cell adhesion molecule (CAM)-mediated pathways, yet the latter route was less affected due to receptor overexpression. In agreement, δ-tocopherol lowered uptake of recombinant ASM by deficient cells (known to occur via the clathrin pathway) and via targeting intercellular adhesion molecule-1 (associated to the CAM pathway). However, the net enzyme activity delivered and lysosomal storage attenuation were greater via the latter route. Data suggest stimulation of exocytosis by tocopherols is not specific of lysosomes and affects endocytic cargo. However, this effect was transient and became unnoticeable several hours after tocopherol removal. Therefore, induction of exocytosis in combination with therapies requiring endocytic uptake, such as ERT, may represent a new type of drug interaction, yet this strategy could be valuable if properly timed for minimal interference.

Biomimetic surface modification of discoidal polymeric particles

The rationale for the design of drug delivery nanoparticles is traditionally based on co-solvent self-assembly following bottom-up approaches or in combination with top-down approaches leading to tailored physiochemical properties to regulate biological responses. However, the optimal design and control of material properties to achieve specific biological responses remain the central challenge in drug delivery research. Considering this goal, we herein designed discoidal polymeric particles (DPPs) whose surfaces are re-engineered with isolated red blood cell (RBC) membranes to tailor their pharmacokinetics. The RBC membrane-coated DPPs (RBC-DPPs) were found to be biocompatible in cell-based in vitro experiments and exhibited extended blood circulation half-life. They also demonstrated unique kinetics at later time points in a mouse model compared to that of bare DPPs. Our results suggested that the incorporation of biomimicry would enable the biomimetic particles to cooperate with systems in the body such as cells and biomolecules to achieve specific biomedical goals.

Bioimaging predictors of rilpivirine biodistribution and antiretroviral activities

Antiretroviral therapy (ART) has changed the outcome of human immunodeficiency virus type one (HIV-1) infection from certain death to a life free of disease co-morbidities. However, infected people must remain on life-long daily ART. ART reduces but fails to eliminate the viral reservoir. In order to improve upon current treatment regimens, our laboratory created long acting slow effective release (LASER) ART nanoformulated prodrugs from native medicines. LASER ART enables antiretroviral drugs (ARVs) to better reach target sites of HIV-1 infection while, at the same time, improve ART's half-life and potency. However, novel ARV design has been slowed by prolonged pharmacokinetic testing requirements. To such ends, tri-modal theranostic nanoparticles were created with single-photon emission computed tomography (SPECT/CT), magnetic resonance imaging (MRI) and fluorescence capabilities to predict LASER ART biodistribution. The created theranostic ARV probes were then employed to monitor drug tissue distribution and potency. Intrinsically 111Indium (111In) radiolabeled, europium doped cobalt-ferrite particles and rilpivirine were encased in a polycaprolactone core surrounded by a lipid shell (111InEuCF-RPV). Particle cell and tissue distribution, and antiretroviral activities were sustained in macrophage tissue depots. 111InEuCF-PCL/RPV particles injected into mice demonstrated co-registration of MRI and SPECT/CT tissue signals with RPV and cobalt. Cell and animal particle biodistribution paralleled ARV activities. We posit that particle selection can predict RPV distribution and potency facilitated by multifunctional theranostic nanoparticles.

Dense and Dynamic Polyethylene Glycol Shells Cloak Nanoparticles from Uptake by Liver Endothelial Cells for Long Blood Circulation

Research into long-circulating nanoparticles has in the past focused on reducing their clearance by macrophages. By engineering a hierarchical polyethylene glycol (PEG) structure on nanoparticle surfaces, we revealed an alternative mechanism to enhance nanoparticle blood circulation. The conjugation of a second PEG layer at a density close to but lower than the mushroom-to-brush transition regime on conventional PEGylated nanoparticles dramatically prolongs their blood circulation via reduced nanoparticle uptake by non-Kupffer cells in the liver, especially liver sinusoidal endothelial cells. Our study also disclosed that the dynamic outer PEG layer reduces protein binding affinity to nanoparticles, although not the total number of adsorbed proteins. These effects of the outer PEG layer diminish in the higher density regime. Therefore, our results suggest that the dynamic topographical structure of nanoparticles is an important factor in governing their fate in vivo. Taken together, this study advances our understanding of nanoparticle blood circulation and provides a facile approach for generating long circulating nanoparticles.

Peptide-Functionalized Hydrogel Cubes for Active Tumor Cell Targeting

Conjugation of bioactive targeting molecules to nano- or micrometer-sized drug carriers is a pivotal strategy to improve their therapeutic efficiency. Herein, we developed pH- and redox-sensitive hydrogel particles with a surface-conjugated cancer cell targeting ligand for specific tumor-targeting and controlled release of the anticancer drug doxorubicin. The poly(methacrylic acid) (PMAA) hydrogel cubes of 700 nm and 2 μm with a hepsin-targeting (IPLVVPL) surface peptide are produced through multilayer polymer assembly on sacrificial cubical mesoporous cores. Direct peptide conjugation to the disulfide-stabilized hydrogels through a thiol-amine reaction does not compromise the structural integrity, hydrophilicity, stability in serum, or pH/redox sensitivity but does affect internalization by cancer cells. The cell uptake kinetics and the ultimate extent of internalization are controlled by the cell type and hydrogel size. The peptide modification significantly promotes the uptake of the 700 nm hydrogels by hepsin-positive MCF-7 cells due to ligand-receptor recognition but has a negligible effect on the uptake of 2 μm PMAA hydrogels. The selectivity of 700 nm IPLVVPL-PMAA hydrogel cubes to hepsin-overexpressing tumor cells is further confirmed by a 3-10-fold higher particle internalization by hepsin-positive MCF-7 and SK-OV-3 compared to that of hepsin-negative PC-3 cells. This work provides a facile method to fabricate enhanced tumor-targeting carriers of submicrometer size and improves the general understanding of particle design parameters for targeted drug delivery.

GRGDS-functionalized chitosan nanoparticles as a potential intravenous hemostat for traumatic hemorrhage control in an animal model

Hemostats, which are used for immediate intervention during internal hemorrhage in order to reduce resulting mortality and morbidity, are relatively rare. Here, we describe novel intravenous nanoparticles (CPG-NPs-2000) with chitosan succinate (CSS) as cores, polyethylene glycol (PEG-2000) as spacers and a glycine-arginine-glycine-aspartic acid-serine (GRGDS) peptide as targeted, active hemostatic motifs. CPG-NPs-2000 displayed significant hemostatic efficacy, compared to the saline control, CSS nanoparticles, and tranexamic acid in liver trauma rat models. Further studies have demonstrated that CPG-NPs-2000 are effectively cleared from organs and blood, within 2 and 48 h, respectively. In addition, administration of CPG-NPs-2000 does not affect clotting function under normal physiological conditions, indicating their potential safety in vivo. CPG-NPs-2000 exhibit excellent thermal stability, good solubility, and redistribution ability, in addition to being low cost. These characteristics indicate that CPG-NPs-2000 may have strong potential as effective intravenous hemostats for treating severe internal bleeding.

Selective ultrasound contrast enhancement in the tumor by nanocapsules with perfluorooctylbromide: effect of PLGA-PEG proportion

We used PLGA-COOH and PLGA-PEG-COOH blended polymer material to encapsulate perfluorooctyl bromide to prepare nanocapsules (NCs) as nano-ultrasound contrast agents. The aim of this study was to assess the effect of PLGA-PEG proportion on the physical, biological and acoustic characteristics of the nanocapsules, and to develop optimal nanocapsules for selective ultrasound contrast enhancement in tumors. The weight ratio of PLGA-PEG in the formulation was 0, 25%, 50%, 75%, and 100%, and the corresponding nanocapsules were designated NCsPLGA, NCs25% PLGA-PEG, NCs50% PLGA-PEG, NCs75% PLGA-PEG and NCs100% PLGA-PEG. As the PLGA-PEG proportion increased, the diameter and bulk modulus of the NCs gradually decreased, and the originally smooth surface of NCs was roughened. NCsPLGA, NCs25% PLGA-PEG and NCs50% PLGA-PEG had regular spherical shape and relatively distinct boundaries compared with NCs75% PLGA-PEG and NCs100% PLGA-PEG, which showed heavy agglomeration. The proportion of PLGA-PEG in the formula could also change the uptake rate of NCs by RAW 264.7 cells. NCs50% PLGA-PEG and NCs75% PLGA-PEG had the lowest uptake by RAW 264.7 cells. In vitro, the ultrasonic gray values of NCs50% PLGA-PEG, NCs75% PLGA-PEG and NCs100% PLGA-PEG were obviously higher than those of NCsPLGA and NCs100% PLGA-PEG. NCsPLGA, NCs50% PLGA-PEG and NCs100% PLGA-PEG were injected into mice via the tail vein, but only NCs50% PLGA-PEG could produce persistent gray contrast enhancement in tumors after 24 h. Histological fluorescence of the tumor tissue confirmed that NCs50% PLGA-PEG and NCs100% PLGA-PEG gathered in tumor tissues. Our results indicate that the PLGA-PEG proportion in the formula is an important factor in constructing optimal nano-ultrasound contrast agents with a liquid core, and could change the nanocapsule size, surface morphology, elastic modulus, macrophage cellular uptake, and ultrasonic reflection. An appropriate PLGA-PEG proportion could help nanoparticles to achieve selective gray contrast enhancement in tumors.

Unintended effects of drug carriers: Big issues of small particles

Humoral and cellular host defense mechanisms including diverse phagocytes, leukocytes, and immune cells have evolved over millions of years to protect the body from microbes and other external and internal threats. These policing forces recognize engineered sub-micron drug delivery systems (DDS) as such a threat, and react accordingly. This leads to impediment of the therapeutic action, extensively studied and discussed in the literature. Here, we focus on side effects of DDS interactions with host defenses. We argue that for nanomedicine to reach its clinical potential, the field must redouble its efforts in understanding the interaction between drug delivery systems and the host defenses, so that we can engineer safer interventions with the greatest potential for clinical success.

Manipulating nanoparticle transport within blood flow through external forces: an exemplar of mechanics in nanomedicine

A large number of nanoparticles (NPs) have been raised for diverse biomedical applications and some of them have shown great potential in treatment and imaging of diseases. Design of NPs is essential for delivery efficacy due to a number of biophysical barriers, which prevents the circulation of NPs in vascular flow and their accumulation at tumour sites. The physiochemical properties of NPs, so-called '4S' parameters, such as size, shape, stiffness and surface functionalization, play crucial roles in their life journey to be delivered to tumour sites. NPs can be modified in various ways to extend their blood circulation time and avoid their clearance by phagocytosis, and efficiently diffuse into tumour cells. However, it is difficult to overcome these barriers simultaneously by a simple combination of '4S' parameters for NPs. At this moment, external triggerings are necessary to guide the movement of NPs, which include light, ultrasound, magnetic field, electrical field and chemical interaction. The delivery system can be constructed to be sensitive to these external stimuli which can reduce the non-specific toxicity and improve the efficacy of the drug-delivery system. From a mechanics point of view, we discuss how different forces play their roles in the margination of NPs in blood flow and tumour microvasculature.

Modulating Phagocytic Cell Sequestration by Tailoring Nanoconstruct Softness

The effect of nanoparticle size, shape, and surface properties on cellular uptake has been extensively investigated for its basic science and translational implications. Recently, softness is emerging as a design parameter for modulating the interaction of nanoparticles with cells and the biological microenvironment. Here, circular, quadrangular, and elliptical polymeric nanoconstructs of different sizes are realized with a Young's modulus ranging from ∼100 kPa (soft) to 10 MPa (rigid). The interaction of these nanoconstructs with professional phagocytic cells is assessed via confocal microscopy and flow cytometry analyses. Regardless of the size and shape, softer nanoconstructs evade cellular uptake up to 5 times more efficiently, by bone-marrow-derived monocytes, as compared to rigid nanoconstructs. Soft circular and quadrangular nanoconstructs are equally uptaken by professional phagocytic cells (<15%); soft elliptical particles are more avidly internalized (<60%) possibly because of the larger size and elongated shape, whereas over 70% of rigid nanoconstructs of any shape and size are uptaken. Inhibition of actin polymerization via cytochalasin D reduces the internalization propensity for all nanoconstruct types. High-resolution live cell microscopy documents that soft nanoconstructs mostly establish short-lived (<30 s) interactions with macrophages, thus diminishing the likelihood of recognition and internalization. The bending stiffness is identified as a discriminating factor for internalization, whereby particles with a bending stiffness slightly higher than cells would more efficiently oppose internalization as compared to stiffer or softer particles. These results confirm that softness is a key parameter in modulating the behavior of nanoparticles and are expected to inspire the design of more efficient nanoconstructs for drug delivery, biomedical imaging, and immunomodulatory therapies.

Biodistribution Analysis of NIR-Labeled Nanogels Using in Vivo FMT Imaging in Triple Negative Human Mammary Carcinoma Models

The purpose of this study is to evaluate the biodistribution properties of random-copolymer-based core-cross-linked nanogels of various sizes and surface poly(ethylene glycol) composition. Systematic variations of near-IR labeled nanogels, comprising varying particle sizes (28-135 nm), PEG corona quantity (0-50 mol %), and PEG length (PEG M_n 1000, 2000, and 5000), were prepared and injected in mice that had been subcutaneously implanted with MDA-MB-231-luc-D3H2LN human mammary carcinoma. In vivo biodistribution was obtained using fluorescence molecular tomography imaging at 0, 6, 24, 48, and 72 h postinjection. Retention of total body probe and percentages of total injected dose in the tumor, liver, spleen, lungs, heart, intestines, and kidneys were obtained. Smaller nanogels (∼30-40 nm) with a high PEG conjugation (∼43-46 mol %) of M_n 2000 on their coronas achieved the highest tumor specificity with peak maximum 27% ID/g, a statistically significant propensity toward accumulation with 16.5% ID/g increase from 0 to 72 h of imaging, which constitutes a 1.5-fold increase. Nanogels with greater tumor localization also had greater retention of total body probe over 72 h. Nanogels without extensive PEGylation were rapidly excreted, even at similar sizes to PEGylated nanogels exhibiting whole body retention. Of all tissues, the liver had the highest % ID, however, like other tissues, it displayed a monotonic decrease over time, suggesting nanogel clearance by hepatic metabolism. Ex vivo quantification of individual tissues from gross necropsy at 72 h postinjection generally correlated with the FMT analysis, providing confidence in tissue signal segmentation in vivo. The parameters determined to most significantly direct a nanogel to the desired tumor target can lead to improve effectiveness for nanogels as therapeutic delivery vehicles.

Subtle changes in network composition impact the biodistribution and tumor accumulation of nanogels

We studied the effect of subtle changes in side-chain chemistry and labelling with near infrared fluorophores of nanogels (NGs) prepared from thiolated poly(glycidol) on in vivo biodistribution in mice bearing human breast tumor xenografts. Side chain chemistry as well as labelling clearly influenced tumor targeting and overall biodistribution.

Anomalous Vascular Dynamics of Nanoworms within Blood Flow

Nanomaterials have been widely used in the design of drug delivery platforms. This work computationally explores the vascular dynamics of nanoworms as drug carriers within blood flow by considering the effects of nanoworm length, stiffness, and local physiological conditions such as hematocrit. We found that nanoworms with length of 8 μm and moderate stiffness are the optimal choice as drug carriers for circulating within normal vascular network due to their lower near wall margination. Compared to those of spherical rigid particles, these nanoworms demonstrate significant demargination behaviors at hematocrit 20%, induced by the local hydrodynamic interactions. Specifically, the interactions between nanoworms and red blood cells create asymmetrical local flow fields, resulting in the demargination of nanoworms. In addition, the flexibility of nanoworms enables them to conform to the deformed shape of red blood cells under shear flow, leading to their high concentration within the core region of vessels. Therefore, the long blood circulation time of nanoworms can be partially attributed to their demargination behaviors and intertwinement with red blood cells. According to these simulation results, tuning the length and stiffness of nanoworms is the key to design drug carries with reduced near wall margination within normal vascular networks and extend their blood circulation time.

Simultaneous Measurements of Geometric and Viscoelastic Properties of Hydrogel Microbeads Using Continuous-Flow Microfluidics with Embedded Electrodes

Geometric and mechanical characterizations of hydrogel materials at the microscale are attracting increasing attention due to their importance in tissue engineering, regenerative medicine, and drug delivery applications. Contemporary approaches for measuring the these properties of hydrogel microbeads suffer from low-throughput, complex system configuration, and measurement inaccuracy. In this work, a continuous-flow device is developed to measure geometric and viscoelastic properties of hydrogel microbeads by flowing the microbeads through a tapered microchannel with an array of interdigitated microelectrodes patterned underneath the channel. The viscoelastic properties are derived from the trajectories of microbeads using a quasi-linear viscoelastic model. The measurement is independent of the applied volumetric flow rate. The results show that the geometric and viscoelastic properties of Ca-alginate hydrogel microbeads can be determined independently and simultaneously. The bulky high-speed optical systems are eliminated, simplifying the system configuration and making it a truly miniaturized device. A throughput of up to 394 microbeads min^-1 is achieved. This study may provide a powerful tool for mechanical profiling of hydrogel microbeads to support their wide applications.

Ameliorating Amyloid-β Fibrils Triggered Inflammation via Curcumin-Loaded Polymeric Nanoconstructs

Inflammation is a common hallmark in several diseases, including atherosclerosis, cancer, obesity, and neurodegeneration. In Alzheimer's disease (AD), growing evidence directly correlates neuronal damage with inflammation of myeloid brain cells, such as microglia. Here, polymeric nanoparticles were engineered and characterized for the delivery of anti-inflammatory molecules to macrophages stimulated via direct incubation with amyloid-β fibers. 200 nm spherical polymeric nanoconstructs (SPNs) and 1,000 nm discoidal polymeric nanoconstructs (DPNs) were synthesized using poly(lactic-co-glycolic acid) (PLGA), polyethylene glycol (PEG), and lipid chains as building blocks. First, the internalization propensity in macrophages of both nanoparticles was assessed via cytofluorimetric and confocal microscopy analyses, demonstrating that SPNs are by far more rapidly taken up as compared to DPNs (99.6 ± 0.11 vs 14.4 ± 0.06%, within 24 h). Then, Curcumin-loaded SPNs (Curc-SPNs) were realized by encapsulating Curcumin, a natural anti-inflammatory molecule, within the PLGA core of SPNs. Finally, Curc-SPNs were shown to diminish up to 6.5-fold the production of pro-inflammatory cytokines-IL-1β; IL-6, and TNF-α-in macrophages stimulated via amyloid-β fibers. Although more sophisticated in vitro models and systematic analyses on the blood-brain barrier permeability are critically needed, these findings hold potential in the development of nanoparticles for modulating inflammation in AD.

Highly efficient delivery of potent anticancer iminoquinone derivative by multilayer hydrogel cubes

We report a novel delivery platform for a highly potent anticancer drug, 7-(benzylamino)-3,4-dihydro-pyrrolo[4,3,2-de]quinolin-8(1H)-one (BA-TPQ), using pH- and redox-sensitive poly(methacrylic acid) (PMAA) hydrogel cubes of micrometer size as the encapsulating matrix. The hydrogels are obtained upon cross-linking PMAA with cystamine in PMAA/poly(N-vinylpyrrolidone) multilayers assembled within mesoporous sacrificial templates. The BA-TPQ-loaded hydrogels maintain their cubical shape and pH-sensitivity after lyophilization, which is advantageous for long-term storage. Conversely, the particles degrade in vitro in the presence of glutathione (5mM) providing 80% drug release within 24h. Encapsulating BA-TPQ into hydrogels significantly increases its transport via Caco-2 cell monolayers used as a model for oral delivery where the apparent permeability of BA-TPQ-hydrogel cubes was∼2-fold higher than that of BA-TPQ. BA-TPQ-hydrogel cubes exhibit better anticancer activity against HepG2 (IC50=0.52µg/mL) and Huh7 (IC50=0.29µg/mL) hepatoma cells with a 40% decrease in the IC50 compared to the non-encapsulated drug. Remarkably, non-malignant liver cells have a lower sensitivity to BA-TPQ-hydrogel cubes with 2-fold increased IC50 values compared to those of cancer cells. In addition, encapsulating BA-TPQ in the hydrogels amplifies the potency of the drug via down-regulation of MDM2 oncogenic protein and upregulation of p53 (a tumor suppressor) and p21 (cell proliferation suppressor) expression in HepG2 liver cancer cells. Moreover, enhanced inhibition of MDM2 protein expression by BA-TPQ-hydrogel cubes is independent of p53 status in Huh7 cells. This drug delivery platform of non-spherical shape provides a facile method for encapsulation of hydrophobic drugs and can facilitate the enhanced efficacy of BA-TPQ for liver cancer therapy.

STATEMENT OF SIGNIFICANCE

Many potent anticancer drugs are hydrophobic and lack tumor selectivity, which limits their application in cancer therapy. Although cubical hydrogels of poly(methacrylic acid) exhibit excellent biocompatibility and versatility, they have not been investigated for hydrophobic drug delivery due to poor mechanical stability and incompatibility between hydrophobic drugs and a hydrophilic hydrogel network. In this study, we provide a facile method to prepare a multilayer hydrogel-based platform with controlled nanostructure, cubical shape and redox-responsiveness for delivery of highly potent anticancer therapeutics, hydrophobic BA-TPQ. The BA-TPQ-hydrogel cubes have exceptional structural stability upon lyophilization which is advantageous for a long-term storage. The greatly enhanced trans-epithelial permeability and amplified anti-tumor activity of BA-TPQ are achieved by encapsulation in these hydrogel cubes. Furthermore, the anticancer BA-TPQ-hydrogel platform retains the selective activity of BA-TPQ to hepatocellular carcinoma cells. Overall, the produced BA-TPQ-hydrogel cubes demonstrate a high potential for clinical liver cancer therapy.

Flow-Induced Shape Reconfiguration, Phase Separation, and Rupture of Bio-Inspired Vesicles

The structural integrity of red blood cells and drug delivery carriers through blood vessels is dependent upon their ability to adapt their shape during their transportation. Our goal is to examine the role of the composition of bio-inspired multicomponent and hairy vesicles on their shape during their transport through in a channel. Through the dissipative particle dynamics simulation technique, we apply Poiseuille flow in a cylindrical channel. We investigate the effect of flow conditions and concentration of key molecular components on the shape, phase separation, and structural integrity of the bio-inspired multicomponent and hairy vesicles. Our results show the Reynolds number and molecular composition of the vesicles impact their flow-induced deformation, phase separation on the outer monolayer due to the Marangoni effect, and rupture. The findings from this study could be used to enhance the design of drug delivery and tissue engineering systems.

Nerve Cells Decide to Orient inside an Injectable Hydrogel with Minimal Structural Guidance

Injectable biomaterials provide the advantage of a minimally invasive application but mostly lack the required structural complexity to regenerate aligned tissues. Here, we report a new class of tissue regenerative materials that can be injected and form an anisotropic matrix with controlled dimensions using rod-shaped, magnetoceptive microgel objects. Microgels are doped with small quantities of superparamagnetic iron oxide nanoparticles (0.0046 vol %), allowing alignment by external magnetic fields in the millitesla order. The microgels are dispersed in a biocompatible gel precursor and after injection and orientation are fixed inside the matrix hydrogel. Regardless of the low volume concentration of the microgels below 3%, at which the geometrical constrain for orientation is still minimum, the generated macroscopic unidirectional orientation is strongly sensed by the cells resulting in parallel nerve extension. This finding opens a new, minimal invasive route for therapy after spinal cord injury.

Protein A Functionalized Polyelectrolyte Microcapsules as a Universal Platform for Enhanced Targeting of Cell Surface Receptors

Targeted delivery systems recognizing specific receptors are a key element in personalized medicine. Such systems allow the delivery of therapeutics to desired sites of the body, increasing their local concentration and thus reducing the side effects. In this study, we fabricate chemically cross-linked (PAH/PAA)₂ microcapsules coated with specific cell-targeting antibodies in random (via direct covalent coupling to the surface) or optimized (via supporting layer of protein A) orientation. We use these antibody-functionalized capsules to target major histocompatibility complex (MHC) class I receptors in living cells and quantify the efficiency of targeting by flow cytometry. We show for the first time the selective binding of polyelectrolyte microcapsules to MHC class I receptors, and confirm that targeting is allotype-specific. Remarkably, protein A assisted immobilization of antibodies enhances targeting efficiency by 40-50% over capsules with randomly attached antibodies. Moreover, biofunctionalized capsules reveal low levels of cytotoxicity and nonspecific binding, excluding the need of additional modification with poly(ethylene glycol). Thus, protein A coated (PAH/PAA)₂ microcapsules represent a unique example of universal targeting tools providing high potential for selective binding to a broad range of cell surface receptors.

Deformable Discoidal Polymeric Nanoconstructs for the Precise Delivery of Therapeutic and Imaging Agents

Over the last 15 years, a plethora of materials and different formulations have been proposed for the realization of nanomedicines. Yet drug-loading efficiency, sequestration by phagocytic cells, and tumor accumulation are sub-optimal. This would imply that radically new design approaches are needed to propel the clinical integration of nanomedicines, overcoming well-accepted clichés. This work briefly reviews the use of deformable discoidal nanoconstructs as a novel delivery strategy for therapeutic and imaging agents. Inspired by blood cell behavior, these nanoconstructs are designed to efficiently navigate the circulatory system, minimize sequestration by phagocytic cells, and recognize the tortuous angiogenic microvasculature of neoplastic masses. This article discusses the notion of nanoparticle margination and vascular adhesion, as well as advantages associated with deformable particles. Finally, details on the synthesis, physico-chemical properties, and in vivo characterization of discoidal polymeric nanoconstructs are provided, with particular emphasis on their ability to independently control size, shape, surface properties, and mechanical stiffness. These nanoconstructs could help in gaining a deeper understanding of the mechanisms regulating the behavior of nanomedicines and identifying optimal delivery strategies for patient-specific therapeutic interventions.

Shaped stimuli-responsive hydrogel particles: syntheses, properties and biological responses

This review summarizes a pool of current experimental approaches and discusses perspectives in the development of the synergistic combination of shape and stimuli-response in particulate hydrogels.