A Metal-Phenolic Network-Enabled Nanoadjuvant to Modulate Immune Responses.

The presence of hierarchical suppressive pathways in the immune system combined with poor delivery efficiencies of adjuvants and antigens to antigen-presenting cells are major challenges in developing advanced vaccines. The present study reports a nanoadjuvant constructed using aluminosilicate nanoparticles (as particle templates), incorporating cytosine-phosphate-guanosine (CpG) oligonucleotides and small-interfering RNA (siRNA) to counteract immune suppression in antigen-presenting cells. Furthermore, the application of a metal-phenolic network (MPN) coating, which can endow the nanoparticles with protective and bioadhesive properties, is assessed with regard to the stability and immune function of the resulting nanoadjuvant in vitro and in vivo. Combining the adjuvanticity of aluminum and CpG with RNA interference and MPN coating results in a nanoadjuvant that exhibits greater accumulation in lymph nodes and elicits improved maturation of dendritic cells in comparison to a formulation without siRNA or MPN, and with no observable organ toxicity. The incorporation of a model antigen, ovalbumin, within the MPN coating demonstrates the capacity of MPNs to load functional biomolecules as well as the ability of the nanoadjuvant to trigger enhanced antigen-specific responses. The present template-assisted fabrication strategy for engineering nanoadjuvants holds promise in the design of delivery systems for disease prevention, as well as therapeutics.

Crystalline Metal-Organic Framework Coatings Engineered via Metal-Phenolic Network Interfaces.

Crystalline metal-organic frameworks (MOFs) have garnered extensive attention owing to their highly ordered porous structure and physicochemical properties. However, their practical application often requires their integration with various substrates, which is challenging because of their weakly adhesive nature and the diversity of substrates that exhibit different properties. Herein, we report the use of amorphous metal-phenolic network coatings to facilitate the growth of crystalline MOF coatings on various particle and planar substrates. Crystalline MOFs with different metal ions and morphologies were successfully deposited on substrates (13 types) of varying sizes, shapes, and surface chemistries. Furthermore, the physicochemical properties of the coated crystalline MOFs (e.g., composition, thickness) could be tuned using different synthesis conditions. The engineered MOF-coated membranes demonstrated excellent liquid and gas separation performance, exhibiting a high H2 permeance of 63200 GPU and a H2/CH4 selectivity of 10.19, likely attributable to the thin nature of the coating (~180 nm), which can be realized using the present strategy. Considering the vast array of MOFs available (>90,000) and the diversity of substrates, this work is expected to pave the way for creating a wide range of MOF composites and coatings with potential applications in biomedicine, environmental science, and agriculture.

Engineering poly(ethylene glycol) particles for targeted drug delivery.

Poly(ethylene glycol) (PEG) is considered to be the "gold standard" among the stealth polymers employed for drug delivery. Using PEG to modify or engineer particles has thus gained increasing interest because of the ability to prolong blood circulation time and reduce nonspecific biodistribution of particles in vivo, owing to the low fouling and stealth properties of PEG. In addition, endowing PEG-based particles with targeting and drug-loading properties is essential to achieve enhanced drug accumulation at target sites in vivo. In this feature article, we focus on recent work on the synthesis of PEG particles, in which PEG is the main component in the particles. We highlight different synthesis methods used to generate PEG particles, the influence of the physiochemical properties of PEG particles on their stealth and targeting properties, and the application of PEG particles in targeted drug delivery.

Metal-Phenolic-Mediated Assembly of Functional Small Molecules into Nanoparticles: Assembly and Bioapplications.

Small molecules, including therapeutic drugs and tracer molecules, play a vital role in biological processing, disease treatment and diagnosis, and have inspired various nanobiotechnology approaches to realize their biological function, particularly in drug delivery. Desirable features of a delivery system for functional small molecules (FSMs) include high biocompatibility, high loading capacity, and simple manufacturing processes, without the need for chemical modification of the FSM itself. Herein, we report a simple and versatile approach, based on metal-phenolic-mediated assembly, for assembling FSMs into nanoparticles (i.e., FSM-MPN NPs) under aqueous and ambient conditions. We demonstrate loading of anticancer drugs, latency reversal agents, and fluorophores at up to ~80 % that is mostly facilitated by π and hydrophobic interactions between the FSM and nanoparticle components. Secondary nanoparticle engineering involving coating with a polyphenol-antibody thin film or sequential co-loading of multiple FSMs enables cancer cell targeting and combination delivery, respectively. Incorporating fluorophores into FSM-MPN NPs enables the visualization of biodistribution at different time points, revealing that most of these NPs are retained in the kidney and heart 24 h post intravenous administration. This work provides a viable pathway for the rational design of small molecule nanoparticle delivery platforms for diverse biological applications.

Emerging Strategies for Immunotherapy of Solid Tumors Using Lipid-Based Nanoparticles.

The application of lipid-based nanoparticles for COVID-19 vaccines and transthyretin-mediated amyloidosis treatment have highlighted their potential for translation to cancer therapy. However, their use in delivering drugs to solid tumors is limited by ineffective targeting, heterogeneous organ distribution, systemic inflammatory responses, and insufficient drug accumulation at the tumor. Instead, the use of lipid-based nanoparticles to remotely activate immune system responses is an emerging effective strategy. Despite this approach showing potential for treating hematological cancers, its application to treat solid tumors is hampered by the selection of eligible targets, tumor heterogeneity, and ineffective penetration of activated T cells within the tumor. Notwithstanding, the use of lipid-based nanoparticles for immunotherapy is projected to revolutionize cancer therapy, with the ultimate goal of rendering cancer a chronic disease. However, the translational success is likely to depend on the use of predictive tumor models in preclinical studies, simulating the complexity of the tumor microenvironment (e.g., the fibrotic extracellular matrix that impairs therapeutic outcomes) and stimulating tumor progression. This review compiles recent advances in the field of antitumor lipid-based nanoparticles and highlights emerging therapeutic approaches (e.g., mechanotherapy) to modulate tumor stiffness and improve T cell infiltration, and the use of organoids to better guide therapeutic outcomes.

YAP Signaling Regulates the Cellular Uptake and Therapeutic Effect of Nanoparticles.

Interactions between living cells and nanoparticles are extensively studied to enhance the delivery of therapeutics. Nanoparticles size, shape, stiffness, and surface charge are regarded as the main features able to control the fate of cell-nanoparticle interactions. However, the clinical translation of nanotherapies has so far been limited, and there is a need to better understand the biology of cell-nanoparticle interactions. This study investigates the role of cellular mechanosensitive components in cell-nanoparticle interactions. It is demonstrated that the genetic and pharmacologic inhibition of yes-associated protein (YAP), a key component of cancer cell mechanosensing apparatus and Hippo pathway effector, improves nanoparticle internalization in triple-negative breast cancer cells regardless of nanoparticle properties or substrate characteristics. This process occurs through YAP-dependent regulation of endocytic pathways, cell mechanics, and membrane organization. Hence, the study proposes targeting YAP may sensitize triple-negative breast cancer cells to chemotherapy and increase the selectivity of nanotherapy.

Particle Engineering via Supramolecular Assembly of Macroscopic Hydrophobic Building Blocks.

Tailoring the hydrophobicity of supramolecular assembly building blocks enables the fabrication of well-defined functional materials. However, the selection of building blocks used in the assembly of metal-phenolic networks (MPNs), an emerging supramolecular assembly platform for particle engineering, has been essentially limited to hydrophilic molecules. Herein, we synthesized and applied biscatechol-functionalized hydrophobic polymers (poly(methyl acrylate) (PMA) and poly(butyl acrylate) (PBA)) as building blocks to engineer MPN particle systems (particles and capsules). Our method allowed control over the shell thickness (e.g., between 10 and 21 nm), stiffness (e.g., from 10 to 126 mN m-1 ), and permeability (e.g., 28-72 % capsules were permeable to 500 kDa fluorescein isothiocyanate-dextran) of the MPN capsules by selection of the hydrophobic polymer building blocks (PMA or PBA) and by controlling the polymer concentration in the MPN assembly solution (0.25-2.0 mM) without additional/engineered assembly processes. Molecular dynamics simulations provided insights into the structural states of the hydrophobic building blocks during assembly and mechanism of film formation. Furthermore, the hydrophobic MPNs facilitated the preparation of fluorescent-labeled and bioactive capsules through postfunctionalization and also particle-cell association engineering by controlling the hydrophobicity of the building blocks. Engineering MPN particle systems via building block hydrophobicity is expected to expand their use.

Engineering Antimicrobial Metal-Phenolic Network Nanoparticles with High Biocompatibility for Wound Healing.

Antibiotic-resistant bacteria pose a global health threat by causing persistent and recurrent microbial infections. To address this issue, antimicrobial nanoparticles (NPs) with low drug resistance but potent bactericidal effects have been developed. However, many of the developed NPs display poor biosafety and their synthesis often involves complex procedures and the antimicrobial modes of action are unclear. Herein, a simple strategy is reported for designing antimicrobial metal-phenolic network (am-MPN) NPs through the one-step assembly of a seeding agent (diethyldithiocarbamate), natural polyphenols, and metal ions (e.g., Cu2+ ) in aqueous solution. The Cu2+ -based am-MPN NPs display lower Cu2+ antimicrobial concentrations (by 10-1000 times) lower than most reported nanomaterials and negligible toxicity across various models, including, cells, blood, zebrafish, and mice. Multiple antimicrobial modes of the NPs have been identified, including bacterial wall disruption, reactive oxygen species production, and quinoprotein formation, with the latter being a distinct pathway identified for the antimicrobial activity of the polyphenol-based am-MPN NPs. The NPs exhibit excellent performance against multidrug-resistant bacteria (e.g., methicillin-resistant Staphylococcus aureus (MRSA)), efficiently inhibit and destroy bacterial biofilms, and promote the healing of MRSA-infected skin wounds. This study provides insights on the antimicrobial properties of metal-phenolic materials and the rational design of antimicrobial metal-organic materials.

Cytoprotective Metal-Phenolic Network Sporulation to Modulate Microalgal Mobility and Division.

Synthetic cell exoskeletons created from abiotic materials have attracted interest in materials science and biotechnology, as they can regulate cell behavior and create new functionalities. Here, a facile strategy is reported to mimic microalgal sporulation with on-demand germination and locomotion via responsive metal-phenolic networks (MPNs). Specifically, MPNs with tunable thickness and composition are deposited on the surface of microalgae cells via one-step coordination, without any loss of cell viability or intrinsic cell photosynthetic properties. The MPN coating keeps the cells in a dormant state, but can be disassembled on-demand in response to environmental pH or chemical stimulus, thereby reviving the microalgae within 1 min. Moreover, the artificial sporulation of microalgae resulted in resistance to environmental stresses (e.g., metal ions and antibiotics) akin to the function of natural sporulation. This strategy can regulate the life cycle of complex cells, providing a synthetic strategy for designing hybrid microorganisms.

Direct Assembly of Metal-Phenolic Network Nanoparticles for Biomedical Applications.

Coordination assembly offers a versatile means to developing advanced materials for various applications. However, current strategies for assembling metal-organic networks into nanoparticles (NPs) often face challenges such as the use of toxic organic solvents, cytotoxicity because of synthetic organic ligands, and complex synthesis procedures. Herein, we directly assemble metal-organic networks into NPs using metal ions and polyphenols (i.e., metal-phenolic networks (MPNs)) in aqueous solutions without templating or seeding agents. We demonstrate the role of buffers (e.g., phosphate buffer) in governing NP formation and the engineering of the NP physicochemical properties (e.g., tunable sizes from 50 to 270 nm) by altering the assembly conditions. A library of MPN NPs is prepared using natural polyphenols and various metal ions. Diverse functional cargos, including anticancer drugs and proteins with different molecular weights and isoelectric points, are readily loaded within the NPs for various applications (e.g., biocatalysis, therapeutic delivery) by direct mixing, without surface modification, owing to the strong affinity of polyphenols to various guest molecules. This study provides insights into the assembly mechanism of metal-organic complexes into NPs and offers a simple strategy to engineer nanosized materials with desired properties for diverse biotechnological applications.

Peptide-Based Coacervate Protocells with Cytoprotective Metal-Phenolic Network Membranes.

Protocells have garnered considerable attention from cell biologists, materials scientists, and synthetic biologists. Phase-separating coacervate microdroplets have emerged as a promising cytomimetic model because they can internalize and concentrate components from dilute surrounding environments. However, the membrane-free nature of such coacervates leads to coalescence into a bulk phase, a phenomenon that is not representative of the cells they are designed to mimic. Herein, we develop a membranized peptide coacervate (PC) with oppositely charged oligopeptides as the molecularly crowded cytosol and a metal-phenolic network (MPN) coating as the membrane. The hybrid protocell efficiently internalizes various bioactive macromolecules (e.g., bovine serum albumin and immunoglobulin G) (>90%) while also resisting radicals due to the semipermeable cytoprotective membrane. Notably, the resultant PC@MPNs are capable of anabolic cascade reactions and remain in discrete protocellular populations without coalescence. Finally, we demonstrate that the MPN protocell membrane can be postfunctionalized with various functional molecules (e.g., folic acid and fluorescence dye) to more closely resemble actual cells with complex membranes, such as recognition molecules, which allows for drug delivery. This membrane-bound cytosolic protocell structure paves the way for innovative synthetic cells with structural and functional complexity.

Engineering Metal-Phenolic Network Nanoparticles via Microfluidics.

Microfluidics opens new avenues for materials engineering, as it enables scalable synthesis and provides highly controllable environments for reactions. Herein, we leverage microfluidics to engineer the properties of (bioactive) metal-phenolic network nanoparticles (MPN NPs), an emerging and highly modular nanoparticle platform for the incorporation and delivery of bioactive cargo. By varying the microfluidics operating parameters (flow rate ratio, total flow rate, temperature) and NP composition, we assemble MPN NPs, which consist of poly(ethylene glycol), biomacromolecules, metal ions, and polyphenols. Compared to MPN NPs prepared via bulk assembly, the microfluidics-assembled MPN NPs possess a broader tunable size range (i.e., ∼40-330 nm vs ∼45-220 nm for bulk-assembled NPs) and a higher (by ∼30%) protein loading. The bulk-assembled MPN NPs show pH-responsive protein release behavior (e.g., ∼50% at pH 7; ∼25% at pH 9; 48 h). Likewise, the MPN NPs prepared via microfluidics at a flow rate ratio of 1:1 display similar pH-responsive protein release behavior. For the microfluidics-assembled MPN NPs, protein release is also dependent on temperature (e.g., 30% at 4 °C, and ∼50% at 20 and 37 °C). Furthermore, assembly at a 1:1 flow rate ratio overall enables greater tunability of protein release profiles than that at higher flow rate ratios. While bulk-assembled NPs display a higher degree of cell association, NPs assembled via both strategies can be internalized by cells after 24 h. These findings provide new insights into engineering the properties of metal-organic materials via microfluidics, which is expected to advance their development and application.

Developing the supraparticle technology for round window-mediated drug administration into the cochlea.

The semi-permeable round window membrane (RWM) is the gateway to the cochlea. Although the RWM is considered a minimally invasive and clinically accepted route for localised drug delivery to the cochlea, overcoming this barrier is challenging, hindering development of effective therapies for hearing loss. Neurotrophin 3 (NT3) is an emerging treatment option for hearing loss, but its therapeutic effect relies on sustained delivery across the RWM into the cochlea. Silica supraparticles (SPs) are drug delivery carriers capable of providing long-term NT3 delivery, when injected directly into the guinea pig cochlea. However, for clinical translation, a RWM delivery approach is desirable. Here, we aimed to test approaches to improve the longevity and biodistribution of NT3 inside the cochlea after RWM implantation of SPs in guinea pigs and cats. Three approaches were tested (i) coating the SPs to slow drug release (ii) improving the retention of SPs on the RWM using a clinically approved gel formulation and (iii) permeabilising the RWM with hyaluronic acid. A radioactive tracer (iodine 125: 125I) tagged to NT3 (125I NT3) was loaded into the SPs to characterise drug pharmacokinetics in vitro and in vivo. The neurotrophin-loaded SPs were coated using a chitosan and alginate layer-by-layer coating strategy, named as '(Chi/Alg)SPs', to promote long term drug release. The guinea pigs were implanted with 5× 125I NT3 loaded (Chi/Alg) SPs on the RWM, while cats were implanted with 30× (Chi/Alg) SPs. A cohort of animals were also implanted with SPs (controls). We found that the NT3 loaded (Chi/Alg)SPs exhibited a more linear release profile compared to NT3 loaded SPs alone. The 125I NT3 loaded (Chi/Alg)SPs in fibrin sealant had efficient drug loading (~5 µg of NT3 loaded per SP that weights ~50 µg) and elution capacities (~49% over one month) in vitro. Compared to the SPs in fibrin sealant, the (Chi/Alg)SPs in fibrin sealant had a significantly slower 125I NT3 drug release profile over the first 7 days in vitro (~12% for (Chi/Alg) SPs in fibrin sealant vs ~43% for SPs in fibrin sealant). One-month post-implantation of (Chi/Alg) SPs, gamma count measurements revealed an average of 0.3 µg NT3 remained in the guinea pig cochlea, while for the cat, 1.3 µg remained. Histological analysis of cochlear tissue revealed presence of a 125I NT3 signal localised in the basilar membrane of the lower basal turn in some cochleae after 4 weeks in guinea pigs and 8 weeks in cats. Comparatively, and in contrast to the in vitro release data, implantation of the SPs presented better NT3 retention and distribution inside the cochlea in both the guinea pigs and cats. No significant difference in drug entry was observed upon acute treatment of the RWM with hyaluronic acid. Collectively, our findings indicate that SPs and (Chi/Alg)SPs can facilitate drug transfer across the RWM, with detectable levels inside the cat cochlea even after 8 weeks with the intracochlear approach. This is the first study to examine neurotrophin pharmacokinetics in the cochlea for such an extended period of times in these two animal species. Whilst promising, we note that outcomes between animals were variable, and opposing results were found between in vitro and in vivo release studies. These findings have important clinical ramifications, emphasising the need to understand the physical properties and mechanics of this complex barrier in parallel with the development of therapies for hearing loss.

Stimuli-Responsive Delivery of Antimicrobial Peptides Using Polyelectrolyte Complexes.

Antimicrobial peptides (AMPs) are antibiotics with the potential to address antimicrobial resistance. However, their translation to the clinic is hampered by issues such as off-target toxicity and low stability in biological media. Stimuli-responsive delivery from polyelectrolyte complexes offers a simple avenue to address these limitations, wherein delivery is triggered by changes occurring during microbial infection. The review first provides an overview of pH-responsive delivery, which exploits the intrinsic pH-responsive nature of polyelectrolytes as a mechanism to deliver these antimicrobials. The examples included illustrate the challenges faced when developing these systems, in particular balancing antimicrobial efficacy and stability, and the potential of this approach to prepare switchable surfaces or nanoparticles for intracellular delivery. The review subsequently highlights the use of other stimuli associated with microbial infection, such as the expression of degrading enzymes or changes in temperature. Polyelectrolyte complexes with dual stimuli-response based on pH and temperature are also discussed. Finally, the review presents a summary and an outlook of the challenges and opportunities faced by this field. This review is expected to encourage researchers to develop stimuli-responsive polyelectrolyte complexes that increase the stability of AMPs while providing targeted delivery, and thereby facilitate the translation of these antimicrobials.

Protease-Responsive Hydrogel Microparticles for Intradermal Drug Delivery.

Protease-responsive multi-arm polyethylene glycol-based microparticles with biscysteine peptide crosslinkers (CGPGG↓LAGGC) were obtained for intradermal drug delivery through inverse suspension photopolymerization. The average size of the spherical hydrated microparticles was ∼40 µm after crosslinking, making them attractive as a skin depot and suitable for intradermal injections, as they are readily dispensable through 27G needles. The effects of exposure to matrix metalloproteinase 9 (MMP-9) on the microparticles were evaluated by scanning electron microscopy and atomic force microscopy, demonstrating partial network destruction and decrease in elastic moduli. Given the recurring course of many skin diseases, the microparticles were exposed to MMP-9 in a flare-up mimicking fashion (multiple-time exposure), showing a significant increase in release of tofacitinib citrate (TC) from the MMP-responsive microparticles, which was not seen for the non-responsive microparticles (polyethylene glycol dithiol crosslinker). It was found that the degree of multi-arm complexity of the polyethylene glycol building blocks can be utilized to tune not only the release profile of TC but also the elastic moduli of the hydrogel microparticles, with Young's moduli ranging from 14 to 140 kPa going from 4-arm to 8-arm MMP-responsive microparticles. Finally, cytotoxicity studies conducted with skin fibroblasts showed no reduction in metabolic activity after 24 h exposure to the microparticles. Overall, these findings demonstrate that protease-responsive microparticles exhibit the properties of interest for intradermal drug delivery.

Functional Ligand-Enabled Particle Assembly for Bio-Nano Interactions.

Functional ligands consist of a wide range of small or large molecules that exhibit a spectrum of physical, chemical, and biological properties. A suite of small molecules (e.g., peptides) or macromolecular ligands (e.g., antibodies and polymers) have been conjugated to particle surfaces for specific applications. However, postfunctionalization of ligands often presents challenges in controlling the surface density and may require the chemical modification of ligands. As an alternative option to postfunctionalization, our work has focused on using functional ligands as building blocks to assemble particles while maintaining their intrinsic (functional) properties. Through self-assembly or template-mediated assembly strategies, we have developed a range of protein-, peptide-, DNA-, polyphenol-, glycogen-, and polymer-based particles. This Account discusses the assembly of such nanoengineered particles, which includes self-assembled nanoparticles, hollow capsules, replica particles, and core-shell particles, according to three categories of functional ligands (i.e., small molecules, polymers, and biomacromolecules) that are used as building blocks for their formation. We discuss a range of covalent and noncovalent interactions among ligand molecules that have been explored to facilitate the assembly of particles. The physicochemical properties of the particles, including size, shape, surface charge, permeability, stability, thickness, stiffness, and stimuli-responsiveness, can be readily controlled by varying the ligand building block or by tuning the assembly method. By selecting specific ligands as building blocks, the bio-nano interactions (i.e., stealth, targeting, and cell trafficking) can also be modulated. For instance, particles composed mainly of low-fouling polymers (i.e., poly(ethylene glycol)) exhibit an extended blood circulation time (half-life > 12 h), while antibody-based nanoparticles demonstrate that a trade-off between stealth and targeting may be required when designing targeting nanoparticle systems. Small molecular ligands, such as polyphenols, have been used as building blocks for particle assembly as they can interact with various biomacromolecules through multiple noncovalent interactions, retain the function of biomacromolecules within the assembly, enable pH-responsive disassembly when coordinating with metal ions, and facilitate endosomal escape of nanoparticles. A perspective is provided on the current challenges associated with the clinical translation of ligand-based nanoparticles. This Account is also expected to serve as a reference to guide the fundamental research and development of functional particle systems assembled from various ligands for diverse applications.

Direct synthesis of amorphous coordination polymers and metal-organic frameworks.

Coordination polymers (CPs) and their subset, metal-organic frameworks (MOFs), can have porous structures and hybrid physicochemical properties that are useful for diverse applications. Although crystalline CPs and MOFs have received the most attention to date, their amorphous states are of growing interest as they can be directly synthesized under mild conditions. Directly synthesized amorphous CPs (aCPs) can be constructed from a wider range of metals and ligands than their crystalline and crystal-derived counterparts and demonstrate numerous unique material properties, such as higher mechanical robustness, increased stability and greater processability. This Review examines methods for the direct synthesis of aCPs and amorphous MOFs, as well as their properties and characterization routes, and offers a perspective on the opportunities for the widespread adoption of directly synthesized aCPs.

Engineering Flexible Metal-Phenolic Networks with Guest Responsiveness via Intermolecular Interactions.

Flexible metal-organic materials are of growing interest owing to their ability to undergo reversible structural transformations under external stimuli. Here, we report flexible metal-phenolic networks (MPNs) featuring stimuli-responsive behavior to diverse solute guests. The competitive coordination of metal ions to phenolic ligands of multiple coordination sites and solute guests (e.g., glucose) primarily determines the responsive behavior of the MPNs, as revealed experimentally and computationally. Glucose molecules can be embedded into the dynamic MPNs upon mixing, leading to the reconfiguration of the metal-organic networks and thus changes in their physicochemical properties for targeting applications. This study expands the library of stimuli-responsive flexible metal-organic materials and the understanding of intermolecular interactions between metal-organic materials and solute guests, which is essential for the rational design of responsive materials for various applications.

An Engineered Nanosugar Enables Rapid and Sustained Glucose-Responsive Insulin Delivery in Diabetic Mice.

Glucose-responsive insulin-delivery platforms that are sensitive to dynamic glucose concentration fluctuations and provide both rapid and prolonged insulin release have great potential to control hyperglycemia and avoid hypoglycemia diabetes. Here, biodegradable and charge-switchable phytoglycogen nanoparticles capable of glucose-stimulated insulin release are engineered. The nanoparticles are "nanosugars" bearing glucose-sensitive phenylboronic acid groups and amine moieties that allow effective complexation with insulin (≈95% loading capacity) to form nanocomplexes. A single subcutaneous injection of nanocomplexes shows a rapid and efficient response to a glucose challenge in two distinct diabetic mouse models, resulting in optimal blood glucose levels (below 200 mg dL-1 ) for up to 13 h. The morphology of the nanocomplexes is found to be key to controlling rapid and extended glucose-regulated insulin delivery in vivo. These studies reveal that the injected nanocomplexes enabled efficient insulin release in the mouse, with optimal bioavailability, pharmacokinetics, and safety profiles. These results highlight a promising strategy for the development of a glucose-responsive insulin delivery system based on a natural and biodegradable nanosugar.

Layer-by-Layer Particles Deliver Epigenetic Silencing siRNA to HIV-1 Latent Reservoir Cell Types.

For over two decades, nanomaterials have been employed to facilitate intracellular delivery of small interfering RNA (siRNA), both in vitro and in vivo, to induce post-transcriptional gene silencing (PTGS) via RNA interference. Besides PTGS, siRNAs are also capable of transcriptional gene silencing (TGS) or epigenetic silencing, which targets the gene promoter in the nucleus and prevents transcription via repressive epigenetic modifications. However, silencing efficiency is hampered by poor intracellular and nuclear delivery. Here, polyarginine-terminated multilayered particles are reported as a versatile system for the delivery of TGS-inducing siRNA to potently suppress virus transcription in HIV-infected cells. siRNA is complexed with multilayered particles formed by layer-by-layer assembly of poly(styrenesulfonate) and poly(arginine) and incubated with HIV-infected cell types, including primary cells. Using deconvolution microscopy, uptake of fluorescently labeled siRNA is observed in the nuclei of HIV-1 infected cells. Viral RNA and protein are measured to confirm functional virus silencing from siRNA delivered using particles 16 days post-treatment. This work extends conventional particle-enabled PTGS siRNA delivery to the TGS pathway and paves the way for future studies on particle-delivered siRNA for efficient TGS of various diseases and infections, including HIV.