Glucose-Regulated Insulin Release from Acid-Disintegrable Microgels Covalently Immobilized with Glucose Oxidase and Catalase

A Biomineralized Bifunctional Patient-Friendly Nanosystem for Sustained Glucose Monitoring and Control in Diabetes

Regular blood glucose monitoring and control is necessary for people with type 1 or advanced type 2 diabetes, yet diagnosing and treating patients with diabetes in an accurate, sustained and patient-friendly manner remains limited. Here, a glucose-responsive bifunctional nanosystem (PGOxMns) is constructed via one-pot biomineralisation of manganese dioxide with glucose oxidase and ε-poly-L-lysine. Under hyperglycaemic conditions, the cascade reactions that occur when glucose interacts with PGOxMns can trigger the production of Mn(II), which enhances the magnetic resonance imaging signal. Simultaneously, manganese dioxide catalyses the decomposition of toxic hydrogen peroxide into oxygen, which also maintains glucose oxidase (GOx) activity. In an in vivo model of diabetes, PGOxMns is used to monitor glucose levels (0-20 mm) and allowed identification of diabetic mice via T1-weighted MRI. Furthermore, PGOxMns is found to have a high insulin-loading capacity (83.6%), likely due to its positive charge. A single subcutaneous injection of insulin-loaded nanosystem (Ins-PGOxMns) into diabetic mice resulted in a rapid and efficient response to a glucose challenge and prolonged blood glucose level control (< 200 mg dL-1) for up to 50 h. Overall, this proof-of-concept study demonstrates the feasibility of using biomineralised nanosystems to develop patient-friendly strategies for glucose monitoring and control.

Intelligent Insulin vs. Artificial Intelligence for Type 1 Diabetes: Will the Real Winner Please Stand Up?

Research in the treatment of type 1 diabetes has been addressed into two main areas: the development of "intelligent insulins" capable of auto-regulating their own levels according to glucose concentrations, or the exploitation of artificial intelligence (AI) and its learning capacity, to provide decision support systems to improve automated insulin therapy. This review aims to provide a synthetic overview of the current state of these two research areas, providing an outline of the latest development in the search for "intelligent insulins," and the results of new and promising advances in the use of artificial intelligence to regulate automated insulin infusion and glucose control. The future of insulin treatment in type 1 diabetes appears promising with AI, with research nearly reaching the possibility of finally having a "closed-loop" artificial pancreas.

pH-Responsive Hexa-Histidine Metal Assembly (HmA) with Enhanced Biocatalytic Cascades as the Vehicle for Glucose-Mediated Long-Acting Insulin Delivery

Diabetes has been listed as one of the three major diseases that endanger human health. Accurately injecting insulin (Ins) depending on the level of blood glucose (LBG) is the standard treatment, especially controlling LBG in the long-term by a single injection. Herein, the pH-responsive hexa-histidine metal assembly (HmA) encapsulated with enzymes (GOx and CAT) and Ins (HmA@GCI) is engineered as the vehicle for glucose-mediated insulin delivery. HmA not only shows high proteins loading efficiency, but also well retained proteins activity and protect proteins from protease damage. Within HmA, the biocatalytic activities of enzymes and the efficiency of the cascade reaction between GOx and CAT are enhanced, leading to a super response to the change of LBG with insulin release and efficient clearance of harmful byproducts of GOx (H2 O2 ). In the treatment of diabetic mice, HmA@GCI reduces LBG to normal in half an hour and maintains for more than 5 days by a single subcutaneous injection, and nearly 24 days with four consecutive injections. During the test period, no symptoms of hypoglycemia and toxicity to tissues and organs are observed. These results indicate that HmA@GCI is a safe and long-acting hypoglycemic agent with prospective clinical application.

Repurposing Pinacol Esters of Boronic Acids for Tuning Viscoelastic Properties of Glucose-responsive Polymer Hydrogels: Effects on Insulin Release Kinetics

In the era of the diabetes pandemic, Injectable hydrogels (HGs) capable of releasing the desired amount of insulin under hyperglycemic conditions will significantly advance smart insulin development. Several smart boronic...

Glucose-Responsive Insulin and Delivery Systems: Innovation and Translation

Type 1 and advanced type 2 diabetes treatment involves daily injections or continuous infusion of exogenous insulin aimed at regulating blood glucose levels in the normoglycemic range. However, current options for insulin therapy are limited by the risk of hypoglycemia and are associated with suboptimal glycemic control outcomes. Therefore, a range of glucose-responsive components that can undergo changes in conformation or show alterations in intermolecular binding capability in response to glucose stimulation has been studied for ultimate integration into closed-loop insulin delivery or "smart insulin" systems. Here, an overview of the evolution and recent progress in the development of molecular approaches for glucose-responsive insulin delivery systems, a rapidly growing subfield of precision medicine, is presented. Three central glucose-responsive moieties, including glucose oxidase, phenylboronic acid, and glucose-binding molecules are examined in detail. Future opportunities and challenges regarding translation are also discussed.

Enzyme production ofd-gluconic acid and glucose oxidase: successful tales of cascade reactions

This review mainly focuses on the use of glucose oxidase in the production ofd-gluconic acid, which is a reactant of undoubtable interest in different industrial areas. As example of diverse enzymatic cascade reactions.

One-pot HTST synthesis of responsive fluorescent ZnO@apo-enzyme composite microgels for intracellular glucometry

One-pot high-temperature short-time heating synthesis allows harnessing of dynamic profile of apo-GOx on ZnO@apo-enzyme composite microgels for intracellular glucometry.

Biologically Inspired and Chemically Derived Methods for Glucose-Responsive Insulin Therapy

The controlled delivery of therapeutics in a manner responsive to physiological indicators has promise in realizing new therapeutic approaches to combat disease. This approach is especially relevant in the context of diabetes. Natural fluctuations in blood glucose seen in the healthy state, complete with peaks and troughs, are poorly regulated as a result of detrimental production or ineffective signaling of the insulin hormone. While several manifestations of diabetes are treated with regularly administered exogenous insulin, the present standard of care results in suboptimal glycemic management that poorly recreates natural hormone control, leading to long-term instability and a significantly increased risk for secondary health complications. New synthetic technologies that make insulin available only when needed, and at the exact dose required, have been explored under the broad vision of realizing a "fully synthetic pancreas." Yet, many challenges remain to realizing a technology that is appropriately responsive, safe, and well integrated into a manageable routine. Herein, many of the approaches explored thus far to sense physiological blood glucose and elicit response through the release of therapeutic insulin are summarized. The approaches point to a new, autonomous approach to managing diabetes with biomimetic therapy.

Microgels in biomaterials and nanomedicines

Microgels are colloidal particles with crosslinked polymer networks and dimensions ranging from tens of nanometers to micrometers. Specifically, smart microgels are fascinating capable of responding to biological signals in vivo or remote triggers and making the possible for applications in biomaterials and biomedicines. Therefore, how to fundamentally design microgels is an urgent problem to be solved. In this review, we put forward our important fundamental opinions on how to devise the intelligent microgels for cancer therapy, biosensing and biological lubrication. We focus on the design ideas instead of specific implementation process by employing reverse synthesis analysis to programme the microgels at the original stage. Moreover, special insights will be, for the first time, as far as we know, dedicated to the particles completely composed of DNA or proteins into microgel systems. These are discussed in detail in this review. We expect to give readers a broad overview of the design criteria and practical methodologies of microgels according to the application fields, as well as to propel the further developments of highly interesting concepts and materials.

Towards feedback-controlled nanomedicines for smart, adaptive delivery

IMPACT STATEMENT

The timing and rate of release of pharmaceuticals from advanced drug delivery systems is an important property that has received considerable attention in the scientific literature. Broadly, these mostly fall into two classes: controlled release with a prolonged release rate or triggered release where the drug is rapidly released in response to an environmental stimulus. This review aims to highlight the potential for developing adaptive release systems that more subtlety modulate the drug release profile through continuous communication with its environment facilitated through feedback control. By reviewing the key elements of this approach in one place (fundamental principles of nanomedicine, enzymatic nanoreactors for medical therapies and feedback-controlled chemical systems) and providing additional motivating case studies in the context of chronobiology, we hope to inspire innovative development of novel "chrononanomedicines."

Tailor-Making Fluorescent Hyaluronic Acid Microgels via Combining Microfluidics and Photoclick Chemistry for Sustained and Localized Delivery of Herceptin in Tumors

Antibody therapeutics, though representing a most used biomedicine, suffers from poor in vivo stability, rapid degradation, and frequent injections. Here, we report that fluorescent hyaluronic acid microgels (HMGs) tailor-made by combining microfluidics and "tetrazole-alkene" photoclick chemistry enable sustained and localized delivery of Herceptin in ovarian tumors. HMGs were obtained with a defined size (25-50 μm), narrow size distribution, high stability, and strong green fluorescence. Notably, HMGs exhibited a remarkably high loading of proteins such as Herceptin and IgG with a loading efficiency exceeding 90% at a theoretical protein-loading content of 30 wt %. In vitro protein release experiments revealed a sustained and hyaluronidase (HAase)-dependent release of Herceptin from HMGs, in which 80.6% of Herceptin was released at 1 U/mL HAase in 10 days. The released Herceptin maintained its secondary structure and antitumor activity. In vivo imaging results demonstrated obviously better tumoral retention for Cy5-labeled Herceptin-loaded HMGs following subcutaneous (sc) injection than for the free-protein counterpart. Interestingly, sc injection of the Herceptin-loaded HMGs into SKOV-3 human ovarian tumor-bearing nude mice at a dose of 30 mg Herceptin equiv/kg induced nearly complete tumor suppression, which was significantly more effective than the sc or systemic injection of free Herceptin. These tailor-made fluorescent HMGs appeared as a robust injectable platform for sustained and localized delivery of therapeutic proteins.

Supersensitive Oxidation-Responsive Biodegradable PEG Hydrogels for Glucose-Triggered Insulin Delivery

Reactive oxygen species (ROS)-responsive polymers and hydrogels represent an emerging family of intelligent materials owing to the key functions of ROS in physiological processes or pathological diseases. Nonetheless, the weaknesses such as low sensitivity, slow response, instability, and low mechanical strength are associated with the limited ROS-responsive polymeric or supramolecular hydrogels. In this study, a novel type of oxidation-responsive degradable hydrogels was fabricated by the redox-initiated radical polymerization of a 4-arm-poly(ethylene glycol) (PEG) acrylic macromonomer that possesses a H₂O₂-cleavable phenylboronic acid linker in each of the arms. The macroscopic hydrogels have the features of good cytocompatibility, moderate mechanical strength, and fast response toward H₂O₂ of low concentration, owing to the covalently cross-linked hydrophilic PEG network and high sensitivity of the linker. They could encapsulate biomacromolecules, such as insulin and glucose oxidase (GOx), with high efficacy, affording a new glucose-responsive insulin-delivery platform on the basis of enzymatic transformation of a biochemical signal (glucose) into an oxidative stimulus (H₂O₂). Interestingly, in vitro results demonstrate that the same GOx-loaded hydrogel exhibited disparate degradation modes under different triggering molecules, that is, bulk degradation by H₂O₂ and surface erosion by glucose. Moreover, compared to the macroscopic hydrogel, the nanogel with a diameter of ∼160 nm prepared by inverse emulsion polymerization showed a much higher degradation rate even under triggering of 20 μM H₂O₂, a pathologically available concentration in vivo.

Temporal switching of an amphiphilic self-assembly by a chemical fuel-driven conformational response

The spatial and temporal control of self-assemblies is the latest scientific hurdle in supramolecular chemistry which is inspired by the functioning of biological systems fueled by chemical signals. In this study, we work towards alleviating this scenario by employing a unique amphiphilic foldamer that operates under the effect of a chemical fuel. The conformational changes in the foldamer amplify into observable morphological changes in its amphiphilic assembly that are controlled by external molecular cues (fuel). We take advantage of this redox responsive foldamer to affect its conformation in a temporal manner by an enzymatic pathway. The temporal characteristics of the transient conformation/assembly can be modulated by varying the concentrations of the fuel and enzyme. We believe that such a design strategy can have positive consequences in designing molecular and supramolecular systems for future active, adaptive and autonomous materials.

Smart approaches to glucose-responsive drug delivery

A grand challenge in the field of "smart" drug delivery has been the quest to create formulations that can sense glucose and respond by delivering an appropriate dose of insulin. This approach, referred to as the "fully synthetic pancreas", envisions closed-loop insulin therapy. The strategies for incorporating glucose sensing into formulations can be broadly categorized into three subsets: enzymatic sensing, natural glucose-binding proteins and synthetic molecular recognition. Here, we highlight some examples of each of these approaches. The challenges remaining en route to the realization of closed-loop insulin therapy are substantial, and include improved response time, more authentic fidelity in glycemic control, improved biocompatibility for delivery materials and assurance of both safety and efficacy. The ubiquitous existence of glucose, combined with the unstable and toxic properties of insulin, further compound efforts towards the generation of a fully synthetic pancreas. However, given the growing incidence of both type-1 and type-2 diabetes, there is significant potential impact from the realization of such an approach on improving therapeutic management of the disease.

Methods for Generating Hydrogel Particles for Protein Delivery

Proteins represent a major class of therapeutic molecules with vast potential for the treatment of acute and chronic diseases and regenerative medicine applications. Hydrogels have long been investigated for their potential in carrying and delivering proteins. As compared to bulk hydrogels, hydrogel microparticles (microgels) hold promise in improving aspects of delivery owing to their less traumatic route of entry into the body and improved versatility. This review discusses common methods of fabricating microgels, including emulsion polymerization, microfluidic techniques, and lithographic techniques. Microgels synthesized from both natural and synthetic polymers are discussed, as are a series of microgels fashioned from environment-responsive materials.

Bioinspired synthesis of poly(phenylboronic acid) microgels with high glucose selectivity at physiological pH

A microgel that is more sensitive towards glucose than to other saccharides is made of 4-vinylphenylboronic acid crosslinked withN,N′-bis(propene)perylene-3,4,9,10-tetracarboxyldiimide.

Glucose-responsive microgels based on apo-enzyme recognition

Glucose-responsive microgels that can undergo reversible and rapid volume phase transitions were made of apo-glucose oxidase interpenetrated in a poly(N-isopropylacrylamide) network.

Nanostructures for peroxidases

Peroxidases are enzymes catalyzing redox reactions that cleave peroxides. Their active redox centers have heme, cysteine thiols, selenium, manganese, and other chemical moieties. Peroxidases and their mimetic systems have several technological and biomedical applications such as environment protection, energy production, bioremediation, sensors and immunoassays design, and drug delivery devices. The combination of peroxidases or systems with peroxidase-like activity with nanostructures such as nanoparticles, nanotubes, thin films, liposomes, micelles, nanoflowers, nanorods and others is often an efficient strategy to improve catalytic activity, targeting, and reusability.

Switchable glucose-responsive volume phase transition behavior of poly(phenylboronic acid) microgels

We report a poly(phenylboronic acid) microgel that can display switchable glucose-responsive volume phase transition behavior with temperature as a trigger.