Gastrointestinal synthetic epithelial linings

Catalase catalyzed tannic acid-Fe3+ network coating: A theranostic strategy for intestinal barrier restoration

Epithelial barrier impairment of intestinal inflammation leads to the leakage of bacteria, antigens and consequent persistent immune imbalance. Restoring the barrier function holds promise for management of intestinal inflammation, while the theragnostic strategies are limited. In this study, we developed a novel coating by catalase (CAT)-catalyzed polymerization of tannic acid (TA) and combined chelation network with Fe3+. TA-Fe3+ coating was self-polymerized in situ along the small intestinal mucosa, demonstrating persistent adhesion properties and protective function. In enteritis models, sequential administration of TA-Fe3+ complex solution effectively restored the barrier function and alleviated the intestinal inflammation. Overexpressed CAT in inflammatory lesion is more favorable for the in situ targeting growth of TA-Fe3+ coating onto the defective barrier. Based on the high longitudinal relaxivity of Fe3+, the pathologically catalyzed coating facilitated the visualization of intestinal barrier impairment through MRI. In conclusion, the novel TA-Fe3+ delivery coating proposed an alternative approach to promote theranostic intervention for intestinal diseases.

Attenuation of inflammatory bowel disease by oral administration of mucoadhesive polydopamine-coated yeast β-glucan via ROS scavenging and gut microbiota regulation

Treatment for inflammatory bowel disease (IBD) is challenging since current anti-inflammatory and immunosuppressive therapies do not address the underlying causes of the illness, which include increased levels of reactive oxygen species (ROS) and dysbiosis of the gut commensal microbiota. Additionally, these treatments often have systemic off-target effects and adverse side effects. In this study, we have developed a prebiotic yeast β-glucan nanocomplex coated with bio-adhesive polydopamine (YBNs@PDA) to effectively prolong their retention time in the gastrointestinal (GI) tract. The oral administration of YBNs@PDA restored the epithelium barriers, reduced ROS levels, and minimized systemic drug exposure while improved therapeutic efficacy in an acute colitis mouse model. Furthermore, 16S ribosomal RNA genes sequencing demonstrated a higher richness and diversity in gut microflora composition following the treatments. In particular, YBNs@PDA markedly augmented the abundance of Lachnospiraceae NK4A136 and Bifidobacterium, both of which are probiotics with crucial roles in relieving colitis via retaining gut homeostasis. Cumulatively, these results demonstrate that the potential of YBNs@PDA as a novel drug-free, ROS-scavenging and gut microbiota regulation nanoplatform for the treatment of GI disorders.

Intestine-Targeted Explosive Hydrogel Microsphere Promotes Uric Acid Excretion for Gout Therapy

Uric acid metabolism disorder triggers metabolic diseases, especially gout. However, increasing uric acid excretion remains a challenge. Here, an accelerative uric acid excretion pathway via an oral intestine-explosive hydrogel microsphere merely containing uricase and dopamine is reported. After oral administration, uricase is exposed and immobilized on intestinal mucosa along with an in situ dopamine polymerization via a cascade reaction triggered by the intestinal specific environment. By this means, trace amount of uricase is required to in situ up-regulate uric acid transporter proteins of intestinal epithelial cells, causing accelerated intestinal uric acid excretion. From in vitro data, the uric acid in fecal samples from gout patients could be significantly reduced by up to 37% by the mimic mucosa-immobilized uricase on the isolated porcine tissues. Both hyperuricemia and acute gouty arthritis in vivo mouse models confirm the uric acid excretion efficacy of intestine-explosive hydrogel microspheres. Fecal uric acid excretion is increased around 30% and blood uric acid is reduced more than 70%. In addition, 16S ribosomal RNA sequencing showed that the microspheres optimized intestinal flora composition as well. In conclusion, a unique pathway via the intestine in situ regulation to realize an efficient uric acid intestinal excretion for gout therapy is developed.

A Mesostructure Multivariant-Assembly Reinforced Ultratough Biomimicking Superglue

The imitation of mussels and oysters to create high-performance adhesives is a cutting-edge field. The introduction of inorganic fillers is shown to significantly alter the adhesive's properties, yet the potential of mesoporous materials as fillers in adhesives is overlooked. In this study, the first report on the utilization of mesoporous materials in a biomimetic adhesive system is presented. Incorporating mesoporous silica nanoparticles (MSN) profoundly enhances the adhesion of pyrogallol (PG)-polyethylene imine (PEI) adhesive. As the MSN concentration increases, the adhesion strength to glass substrates undergoes an impressive fivefold improvement, reaching an outstanding 2.5 mPa. The adhesive forms an exceptionally strong bond, to the extent that the glass substrate fractures before joint failure. The comprehensive tests involving various polyphenols, polymers, and fillers reveal an intriguing phenomenon-the molecular structure of polyphenols significantly influences adhesive strength. Steric hindrance emerges as a crucial factor, regulating the balance between π-cation and charge interactions, which significantly impacts the multicomponent assembly of polyphenol-PEI-MSN and, consequently, adhesive strength. This groundbreaking research opens new avenues for the development of novel biomimetic materials.

Intestinal retentive systems - recent advances and emerging approaches

Intestinal retentive devices (IRDs) are devices designed to anchor within the lumen of the intestines for long-term residence in the gastrointestinal tract. IRDs can enable impactful medical device technologies including sustained oral drug delivery systems, indwelling sensors, or real-time diagnostics. The design and testing of IRDs present a myriad of challenges, including precise deployment of the device at desired intestinal locations, secure anchoring within the gastrointestinal tract to allow for natural function, and safe removal of the IRD at user-defined times. Advancing the state-of-the-art of IRD is an interdisciplinary effort that requires innovations such as new materials, novel anchoring mechanisms, and medical device design with consistent input from clinical practitioners and end-users. This perspective briefly reviews the current state-of-the-art for IRDs and charts a path forward to inform the design of future concepts. Specifically, this article will highlight materials, retention mechanisms, and test beds to measure the efficacy of IRDs and their mechanisms. Finally, potential synergies between IRD and other medical device technologies are presented to identify future opportunities.

Pathologically catalyzed physical coating restores the intestinal barrier for inflammatory bowel disease therapy

Intestinal epithelia impairment of inflammatory bowel disease (IBD) leads to the leakage of bacteria and antigens and the consequent persistent immune imbalance. Restoring the epithelial barrier is a promising therapeutic target but lacks effective and safe clinical interventions. By identifying the catalase (CAT) presence in the IBD pathological environment, we herein develop a CAT-catalyzed pathologically coating on the damaged epithelial barrier to inhibit intestinal leakage for IBD therapy. With the codelivery of CaO2 (a CAT substrate) and dopamine, the nanosystem can enable CAT-catalyzed oxygen (O2) production and in-situ polymerization of dopamine and then yield a thin and integrative polydopamine (PDA) coating on the intestinal barrier due to the highly adhesive property of PDA. In vivo study demonstrates that PDA coating provides not only a protective barrier by restricting intestinal leakage but also a favorable anti-inflammation effect. Beyond drug management, this work provides a physical repair strategy via catalyzed coating for IBD therapy.

Stimulation-responsive mucoadhesive probiotics for inflammatory bowel disease treatment by scavenging reactive oxygen species and regulating gut microbiota

Inflammatory bowel disease (IBD) is characterized by the high level of reactive oxygen species (ROS) and highly dysfunctional intestinal flora. Here, a stimulation-responsive mucoadhesive probiotic Lac@HDP was rationally constructed for achieving specific adhesion of colitis site and depleting high level of ROS in inflammatory site. Briefly, Lac is Lactobacillus acidophilus, HDP is obtained by hyaluronic acid grafted with dopamine protected by phenylboric acid. Specifically, by consuming a large amount of ROS, phenyl borate group of Lac@HDP is oxidized and fractured, thus exposing the catechol hydroxyl group and obtaining strong mucosal adhesion ability, thereby significantly prolong the retention time of Lac in the inflammatory site. In the murine model of acute and chronic colitis, the stimulation-responsive mucoadhesive probiotics were significantly more effective in alleviating colitis symptoms than antioxidants and probiotics alone. In addition, the abundance and diversity of intestinal flora were increased after treatment with Lac@HDP, which was helpful to alleviate IBD. Importantly, the stimulation-responsive mucoadhesive probiotics have good biological safety in vivo, which provides the prospect of clinical application in the future.

A Transformable Mucoadhesive Microgel Network for Noninvasive Multimodal Imaging And Radioprotection of a Large Area of the Gastrointestinal Tract

The lack of noninvasive imaging and modulation of a large area of the gastrointestinal (GI) tract constrain the diagnosis and treatment of many GI-related diseases. Recent advances use novel mucoadhesive materials to coat a part of the GI tract and then modulate its functions. High mucoadhesion is the key factor of the partial coating, but also the limitation for not spreading and covering the lower GI tract. Here, a bismuth-pectin organic-inorganic hybrid complex is screened and engineered into a transformable microgel network (Bi-GLUE) with high flowability and mucoadhesion, such that it can quickly transit through and coat a large area of the GI tract. In murine and porcine models, Bi-GLUE delivers contrast agents to achieve real-time, large-area GI-tract imaging under X-ray or magnetic resonance  modalities and to facilitate the non-invasive diagnosis of familial adenomatous polyposis. Moreover, Bi-GLUE, like an intracorporal radiation shield, decreases the radiotoxicity in a whole-abdomen irradiation rat model. This transformable microgel network offers a new direction that can modulate a large area of the GI tract and may have broad applications for GI-related conditions.

Villi Inspired Mechanical Interlocking for Intestinal Retentive Devices

Intestinal retentive devices have applications ranging from sustained oral drug delivery systems to indwelling ingestible medical devices. Current strategies to retain devices in the small intestine primarily focus on chemical anchoring using mucoadhesives or mechanical coupling using expandable devices or structures that pierce the intestinal epithelium. Here, the feasibility of intestinal retention using devices containing villi-inspired structures that mechanically interlock with natural villi of the small intestine is evaluated. First the viability of mechanical interlocking as an intestinal retention strategy is estimated by estimating the resistance to peristaltic shear between simulated natural villi and devices with various micropost geometries and parameters. Simulations are validated in vitro by fabricating micropost array patches via multistep replica molding and performing lap-shear tests to evaluate the interlocking performance of the fabricated microposts with artificial villi. Finally, the optimal material and design parameters of the patches that can successfully achieve retention in vivo are predicted. This study represents a proof-of-concept for the viability of micropost-villi mechanical interlocking strategy to develop nonpenetrative multifunctional intestinal retentive devices for the future.

Mucosa-Mimetic Materials for the Study of Intestinal Homeostasis and Disease

Mucus is a viscoelastic hydrogel that lines and protects the epithelial surfaces of the body that houses commensal microbiota and functions in host defense against pathogen invasion. As a first-line physical and biochemical barrier, intestinal mucus is involved in immune surveillance and spatial organization of the microbiome, while dysfunction of the gut mucus barrier is implicated in several diseases. Mucus can be collected from a variety of mammalian sources for study, however, established methods are challenging in terms of scale and efficiency, as well as with regard to rheological similarity to native human mucus. Therefore, there is a need for mucus-mimetic hydrogels that more accurately reflect the physical and chemical profile of the in vivo human epithelial environment to enable the investigation of the role of mucus in human disease and interactions with the intestinal microbiome. This review will evaluate the material properties of synthetic mucus mimics to date designed to address the above need, with a focus toward an improved understanding of the biochemical and immunological functions of these biopolymers related to utility for research and therapeutic applications.

Enzyme-Triggered Intestine-Specific Targeting Adhesive Platform for Universal Oral Drug Delivery

Patient adherence to chronic therapies can be suboptimal, leading to poor therapeutic outcomes. Dosage forms that enable reduction in dosing frequency stand to improve patient adherence. Variation in gastrointestinal transit time, inter-individual differences in gastrointestinal physiology and differences in physicochemical properties of drugs represent challenges to the development of such systems. To this end, a small intestine-targeted drug delivery system is developed, where prolonged gastrointestinal retention and sustained release are achieved through tissue adhesion of drug pills mediated by an essential intestinal enzyme catalase. Here proof-of-concept pharmacokinetics is demonstrated in the swine model for two drugs, hydrophilic amoxicillin and hydrophobic levodopa. It is anticipated that this system can be applicable for many drugs with a diverse of physicochemical characteristics.

Gastrointestinal Delivery of an mRNA Vaccine Using Immunostimulatory Polymeric Nanoparticles

mRNA vaccines can be translated into protein antigens, in vivo, to effectively induce humoral and cellular immunity against these proteins. While current mRNA vaccines have generated potent immune responses, the need for ultracold storage conditions (- 80 °C) and healthcare professionals to administer the vaccine through the parenteral route has somewhat limited their distribution in rural areas and developing countries. Overcoming these challenges stands to transform future deployment of mRNA vaccines. In this study, we developed an mRNA vaccine that can trigger a systemic immune response through administration via the gastrointestinal (GI) tract and is stable at 4 °C. A library of cationic branched poly(β-amino ester) (PBAE) polymers was synthesized and characterized, from which a polymer with high intracellular mRNA delivery efficiency and immune stimulation capacity was down-selected. mRNA vaccines made with the lead polymer-elicited cellular and humoral immunity in mice. Furthermore, lyophilization conditions of the formulation were optimized to enable storage under refrigeration. Our results suggest that PBAE nanoparticles are potent mRNA delivery platforms that can elicit B cell and T cell activation, including antigen-specific cellular and humoral responses. This system can serve as an easily administrable, potent oral mRNA vaccine.

Genetically targeted chemical assembly of polymers specifically localized extracellularly to surface membranes of living neurons

Multicellular biological systems, particularly living neural networks, exhibit highly complex organization properties that pose difficulties for building cell-specific biocompatible interfaces. We previously developed an approach to genetically program cells to assemble structures that modify electrical properties of neurons in situ, opening up the possibility of building minimally invasive cell-specific structures and interfaces. However, the efficiency and biocompatibility of this approach were challenged by limited membrane targeting of the constructed materials. Here, we design a method for highly localized expression of enzymes targeted to the plasma membrane of primary neurons, with minimal intracellular retention. Next, we show that polymers synthesized in situ by this approach form dense extracellular clusters selectively on the targeted cell membrane and that neurons remain viable after polymerization. Last, we show generalizability of this method across a range of design strategies. This platform can be readily extended to incorporate a broad diversity of materials onto specific cell membranes within tissues and may further enable next-generation biological interfaces.

In Situ Polymerization-Mediated Antigen Presentation

Activating antigen-presenting cells is essential to generate adaptive immunity, while the efficacy of conventional activation strategies remains unsatisfactory due to suboptimal antigen-specific priming. Here, in situ polymerization-mediated antigen presentation (IPAP) is described, in which antigen-loaded nanovaccines are spontaneously formed and efficiently anchored onto the surface of dendritic cells in vivo through co-deposition with dopamine. The resulting chemically bound nanovaccines can promote antigen presentation by elevating macropinocytosis-based cell uptake and reducing lysosome-related antigen degradation. IPAP is able to prolong the duration of antigen reservation in the injection site and enhance subsequent accumulation in the draining lymph nodes, thereby eliciting robust antigen-specific cellular and humoral immune responses. IPAP is also applicable for different antigens and capable of circumventing the disadvantages of complicated preparation and purification. By implementation with ovalbumin, IPAP induces a significant protective immunity against ovalbumin-overexpressing tumor cell challenge in a prophylactic murine model. The use of the SARS-CoV-2 Spike protein S1 subunit also remarkably increases the production of S1-specific immunoglobulin G in mice. IPAP offers a unique strategy for stimulating antigen-presenting cells to boost antigen-specific adaptive responses and proposes a facile yet versatile method for immunization against various diseases.

Soft robot-enabled controlled release of oral drug formulations

The creation of highly effective oral drug delivery systems (ODDSs) has long been the main objective of pharmaceutical research. Multidisciplinary efforts involving materials, electronics, control, and pharmaceutical sciences encourage the development of robot-enabled ODDSs. Compared with conventional rigid robots, soft robots potentially offer better mechanical compliance and biocompatibility with biological tissues, more versatile shape control and maneuverability, and multifunctionality. In this paper, we first describe and highlight the importance of manipulating drug release kinetics, i.e. pharmaceutical kinetics. We then introduce an overview of state-of-the-art soft robot-based ODDSs comprising resident, shape-programming, locomotive, and integrated soft robots. Finally, the challenges and outlook regarding future soft robot-based ODDS development are discussed.

Gut epithelial barrier damage caused by dishwasher detergents and rinse aids

BACKGROUND

The increased prevalence of many chronic inflammatory diseases linked to gut epithelial barrier leakiness has prompted us to investigate the role of extensive use of dishwasher detergents, among other factors.

OBJECTIVE

We sought to investigate the effects of professional and household dishwashers, and rinse agents, on cytotoxicity, barrier function, transcriptome, and protein expression in gastrointestinal epithelial cells.

METHODS

Enterocytic liquid-liquid interfaces were established on permeable supports, and direct cellular cytotoxicity, transepithelial electrical resistance, paracellular flux, immunofluorescence staining, RNA-sequencing transcriptome, and targeted proteomics were performed.

RESULTS

The observed detergent toxicity was attributed to exposure to rinse aid in a dose-dependent manner up to 1:20,000 v/v dilution. A disrupted epithelial barrier, particularly by rinse aid, was observed in liquid-liquid interface cultures, organoids, and gut-on-a-chip, demonstrating decreased transepithelial electrical resistance, increased paracellular flux, and irregular and heterogeneous tight junction immunostaining. When individual components of the rinse aid were investigated separately, alcohol ethoxylates elicited a strong toxic and barrier-damaging effect. RNA-sequencing transcriptome and proteomics data revealed upregulation in cell death, signaling and communication, development, metabolism, proliferation, and immune and inflammatory responses of epithelial cells. Interestingly, detergent residue from professional dishwashers demonstrated the remnant of a significant amount of cytotoxic and epithelial barrier-damaging rinse aid remaining on washed and ready-to-use dishware.

CONCLUSIONS

The expression of genes involved in cell survival, epithelial barrier, cytokine signaling, and metabolism was altered by rinse aid in concentrations used in professional dishwashers. The alcohol ethoxylates present in the rinse aid were identified as the culprit component causing the epithelial inflammation and barrier damage.

Mucoadhesive probiotic backpacks with ROS nanoscavengers enhance the bacteriotherapy for inflammatory bowel diseases

Inflammatory bowel diseases (IBDs) are often associated with elevated levels of reactive oxygen species (ROS) and highly dysregulated gut microbiota. In this study, we synthesized a polymer of hyaluronic acid-poly(propylene sulfide) (HA-PPS) and developed ROS-scavenging nanoparticles (HPN) that could effectively scavenge ROS. To achieve colon tissue targeting effects, the HPN nanoparticles were conjugated to the surface of modified probiotic Escherichia coli Nissle 1917 (EcN). To enhance the bacteriotherapy of EcN, we encapsulated EcN cells with a poly-norepinephrine (NE) layer that can protect EcN against environmental assaults to improve the viability of EcN in oral delivery and prolong the retention time of EcN in the intestine due to its strong mucoadhesive capability. In the dextran sulfate sodium-induced mouse colitis models, HPN-NE-EcN showed substantially enhanced prophylactic and therapeutic efficacy. Furthermore, the abundance and diversity of gut microbiota were increased after treatment with HPN-NE-EcN, contributing to the alleviation of IBDs.

Mucosa-interfacing electronics

The surface mucosa that lines many of our organs houses myriad biometric signals and, therefore, has great potential as a sensor-tissue interface for high-fidelity and long-term biosensing. However, progress is still nascent for mucosa-interfacing electronics owing to challenges with establishing robust sensor-tissue interfaces; device localization, retention and removal; and power and data transfer. This is in sharp contrast to the rapidly advancing field of skin-interfacing electronics, which are replacing traditional hospital visits with minimally invasive, real-time, continuous and untethered biosensing. This Review aims to bridge the gap between skin-interfacing electronics and mucosa-interfacing electronics systems through a comparison of the properties and functions of the skin and internal mucosal surfaces. The major physiological signals accessible through mucosa-lined organs are surveyed and design considerations for the next generation of mucosa-interfacing electronics are outlined based on state-of-the-art developments in bio-integrated electronics. With this Review, we aim to inspire hardware solutions that can serve as a foundation for developing personalized biosensing from the mucosa, a relatively uncharted field with great scientific and clinical potential.

A Dopamine-Enabled Universal Assay for Catalase and Catalase-Like Nanozymes

Developing a universal strategy to measure catalase (CAT)/CAT-like activity, on one hand, overcomes limitations on current assays, such as moderate sensitivity and limited sample scope; on the other hand, facilitates insightful studies on applications of CAT and CAT-like nanozymes. Herein, the oxygen-sensitive and H₂O₂-inhibitory self-polymerization of dopamine (DA) was demonstrated as an activity indicator of CAT or CAT-like nanozymes, which monitors the catalytically generated O₂ in a hypoxic environment. A typical assay for natural CAT was achieved under the optimized conditions. Moreover, this assay was suitable for diverse types of samples, ranging from nanozymes, animal tissues, to human saliva. By comparing the merits and limitations of common methods, this assay shows all-round advantages in sensitivity, specificity, and versatility, facilitating the formulation of measurement criteria and the development of potential standardized assays for CAT (or CAT-like nanozyme) activity.

Cascade Reaction of "Mn2+ -Catechol" Triggered by H2 O2 to Integrate Firm Tumor Vessel Embolization and Hypoxic Response Relief

Transcatheter arterial embolization (TAE) therapy requires firm and long-term vessel embolization without recanalization. However, firm embolization usually leads to unanticipated hypoxic response which promotes tumor recurrence and metastasis. Herein, an injectable thermosensitive hydrogel containing catechol groups and Mn²⁺ (PNDM) has been developed to enhance embolization and inhibit hypoxic response utilizing augmented H₂ O₂ after TAE. This novel embolic agent converts H₂ O₂ into hydroxyl radicals via Mn²⁺ -dependent Fenton-like reaction, which are subsequently scavenged through a "catechol-quinone" transition to supress hypoxic responses. Quinone structure can not only make hydrogel internal structure more compact, but also enhance hydrogel adhesion to vessel wall. In vivo experiments confirm that the rabbit renal artery can be firmly embolized for 84 days. Studies in liver VX2 tumor-bearing rabbits demonstrate the PNDM-based TAE can promote tumor necrosis, inhibit angiogenesis and tumor metastasis, and greatly prolong rabbit survival. This strategy opens new sights in the TAE therapy for liver cancer. This article is protected by copyright. All rights reserved.

Harnessing Oxidative Microenvironment for In Vivo Synthesis of Subcellular Conductive Polymer Microesicles Enhances Nerve Reconstruction

Conductive polymers (CPs) are promising biomaterials to address signal connection at biointerfaces for tissue regeneration. However, regulating material microstructure at the subcellular scale to provide a more seamless interface between conductive substrates and cells remains a great challenge. Here, we demonstrate that chemical factors and enzyme-carried subcellular structures at lesion site provide a natural bioreactor to self-assemble conductive microvesicles (CMVs) for improving bioelectrical signal reconstruction. The synthesized CMVs contribute to the electrical conduction of the injured nerve in the early stage. Moreover, CMVs are eventually expelled via lymphatic capillary to minimize space-occupying and chronic inflammation. Therefore, we provide a prototype to integrate specific physiological microenvironments and polymer chemistry to manufacture subcellular functional materials with self-adaptive interface in vivo for biomedical applications.

Foundations of gastrointestinal-based drug delivery and future developments

Gastrointestinal-based drug delivery is considered the preferred mode of drug administration owing to its convenience for patients, which improves adherence. However, unique characteristics of the gastrointestinal tract (such as the digestive environment and constraints on transport across the gastrointestinal mucosa) limit the absorption of drugs. As a result, many medications, in particular biologics, still exist only or predominantly in injectable form. In this Review, we examine the fundamentals of gastrointestinal drug delivery to inform clinicians and pharmaceutical scientists. We discuss general principles, including the challenges that need to be overcome for successful drug formulation, and describe the unique features to consider for each gastrointestinal compartment when designing drug formulations for topical and systemic applications. We then discuss emerging technologies that seek to address remaining obstacles to successful gastrointestinal-based drug delivery.

Versatile Polymer Nanocapsules via Redox Competition

Polymer nanocapsules have demonstrated significant value in materials science and biomedical technology, but require complicated and time-consuming synthetic steps. We report here the facile synthesis of monodisperse polymer nanocapsules via a redox-mediated kinetic strategy from two simple molecules: dopamine and benzene-1,4-dithiol (BDT). Specifically, BDT forms core templates and modulates the oxidation kinetics of dopamine into polydopamine (PDA) shells. These uniform nanoparticles can be tuned between ≈70 and 200 nm because the core diameter directly depends on BDT while the shell thickness depends on dopamine. The supramolecular core can then rapidly disassemble in organic solvents to produce PDA nanocapsules. Such nanocapsules exhibit enhanced physicochemical performance (e.g., loading capacity, photothermal transduction, and anti-oxidation) versus their solid counterparts. Particularly, this method enables a straightforward encapsulation of functional nanoparticles providing opportunities for designing complex nanostructures such as yolk-shell nanoparticles.

Magneto-Responsive Microneedle Robots for Intestinal Macromolecule Delivery

Oral administration is the most convenient and commonly used approach for drug delivery, while it is still a challenge to overcome the complicated gastrointestinal barriers and realize efficient macromolecular drug absorption. Here, novel magneto-responsive microneedle robots are presented for efficient oral delivery of versatile macromolecules. These microneedle robots with three components of the magnetic substrate, the separable connection, and tips are generated by a Lego-brick-stacking-inspired multistage 3D fabrication strategy. With the assistance of commercial enteric capsule encapsulation, they can be taken orally and be released when entering the small intestine. Benefitting from their polarized magnetic substrate, the tips of the microneedle robots can orient to the small intestinal wall, overcome the barriers, insert into the tissue, and deliver encapsulated actives under specific magnetic fields. Besides, after the separable connection degrades, the tips can be left inside the tissue for continuous actives release, and the magnetic substrate can be excreted safely. Based on these features, the practical values of the microneedle robots are demonstrated by using them to orally deliver insulin and efficiently regulate the blood glucose of pigs. It is believed that the proposed microneedle robots can orally deliver diverse macromolecules and thus open a new chapter for oral administration.

Design Challenges in Polymeric Scaffolds for Tissue Engineering

Numerous surgical procedures are daily performed worldwide to replace and repair damaged tissue. Tissue engineering is the field devoted to the regeneration of damaged tissue through the incorporation of cells in biocompatible and biodegradable porous constructs, known as scaffolds. The scaffolds act as host biomaterials of the incubating cells, guiding their attachment, growth, differentiation, proliferation, phenotype, and migration for the development of new tissue. Furthermore, cellular behavior and fate are bound to the biodegradation of the scaffold during tissue generation. This article provides a critical appraisal of how key biomaterial scaffold parameters, such as structure architecture, biochemistry, mechanical behavior, and biodegradability, impart the needed morphological, structural, and biochemical cues for eliciting cell behavior in various tissue engineering applications. Particular emphasis is given on specific scaffold attributes pertaining to skin and brain tissue generation, where further progress is needed (skin) or the research is at a relatively primitive stage (brain), and the enumeration of some of the most important challenges regarding scaffold constructs for tissue engineering.

Phenolic-enabled nanotechnology: versatile particle engineering for biomedicine

Phenolics are ubiquitous in nature and have gained immense research attention because of their unique physiochemical properties and widespread industrial use. In recent decades, their accessibility, versatile reactivity, and relative biocompatibility have catalysed research in phenolic-enabled nanotechnology (PEN) particularly for biomedical applications which have been a major benefactor of this emergence, as largely demonstrated by polydopamine and polyphenols. Therefore, it is imperative to overveiw the fundamental mechanisms and synthetic strategies of PEN for state-of-the-art biomedical applications and provide a timely and comprehensive summary. In this review, we will focus on the principles and strategies involved in PEN and summarize the use of the PEN synthetic toolkit for particle engineering and the bottom-up synthesis of nanohybrid materials. Specifically, we will discuss the attractive forces between phenolics and complementary structural motifs in confined particle systems to synthesize high-quality products with controllable size, shape, composition, as well as surface chemistry and function. Additionally, phenolic's numerous applications in biosensing, bioimaging, and disease treatment will be highlighted. This review aims to provide guidelines for new scientists in the field and serve as an up-to-date compilation of what has been achieved in this area, while offering expert perspectives on PEN's use in translational research.