Engineered insulin-polycation complexes for glucose-responsive delivery with high insulin loading

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.

The Use of a Barley-Based Well to Define Cationic Betaglucan to Study Mammalian Cell Toxicity Associated with Interactions with Biological Structures

Among potential macromolecule-based pharmaceuticals, polycations seem particularly interesting due to their proven antimicrobial properties and use as vectors in gene therapy. This makes an understanding of the mechanisms of these molecules' interaction with living structures important, so the goal of this paper was to propose and carry out experiments that will allow us to characterize these phenomena. Of particular importance is the question of toxicity of such structures to mammalian cells and, in the work presented here, two lines, normal fibroblasts 3T3-L1 and A549 lung cancer, were used to determine this. In this work, three well-defined cationic derivatives of barley-derived betaglucans obtained in a reaction with glycidyltrimethylammonium chloride (BBGGTMAC) with different degrees of cationization (50, 70, and 100% per one glucose unit) and electrostatic charge were studied. The studies address interactions of these polymers with proteins (bovine serum proteins and BSA), nucleic acids (DNA), glycosaminoglycans (heparin), and biological membranes. The results described in this study make it possible to indicate that toxicity is most strongly influenced by interactions with biological membranes and is closely related to the electrostatic charge of the macromolecule. The presentation of this observation was the goal of this publication. This paper also shows, using fluorescently labeled variants of polymers, the penetration and impact on cell structure (only for the polymer with the highest substitution binding to cell membranes is observed) by using confocal and SEM (for the polymer with the highest degree of substitution, and the appearance of additional structures on the surface of the cell membrane is observed). The labeled polymers are also tools used together with dynamic light scattering and calorimetric titration to study their interaction with other biopolymers. As for the interactions with biological membranes, lipid Langmuir monolayers as model membrane systems were used.

Molecular Docking-Guided Design on Glucose-Responsive Nanoparticles for Microneedle Fabrication and "Three-Meal-per-Day" Blood-Glucose Regulation

It was greatly significant, but difficult, to develop stimulus-responsive polymeric nanoparticles with efficient protein-loading and protein-delivering properties. Crucial obstacles were the ambiguous protein/nanoparticle-interacting mechanisms and the corresponding inefficient trial-and-error strategies, which brought large quantities of experiments in design and optimization. In this work, a molecular docking-guided universal "segment-functional group-polymer" process was proposed to simplify the previous laborious experimental step. The insulin-delivering glucose-responsive polymeric nanoparticles for diabetic treatments were taken as the examples. The molecular docking study obtained insights from the insulin/segment interactions. It was then experimentally confirmed in six functional groups for insulin-loading performances of their corresponding polymers. The optimization formulation was further proved effective in blood-glucose stabilization on the diabetic rats under the "three-meal-per-day" mode. It was believed that the molecular docking-guided designing process was promising in the protein-delivering field.

Charge modifications of graphene oxide enhance the inhibitory effect on insulin amyloid fibrillation based on electrostatic interactions

Graphene oxide (GO) is a biocompatible nanomaterial that has an inhibitory effect on insulin amyloid fibrillation. In order to enhance the inhibitory effect of GO and explore the rules of electrostatic interactions on the inhibitory effect, carboxyl group, PEI and PEG were coupled to the GO nanoplatelet surface to prepare inhibitors of different surface electrical properties. The effects of surface electrical properties of inhibitors on insulin fibrillation were investigated. The results showed that GO, carboxyl group modified GO (GO-COOH), PEI modified GO (GO-PEI), and PEG modified GO (GO-PEG) inhibited insulin fibrillation in a dose-dependent manner. Compared with GO, positive charge-modified GO-PEI and negative charge-modified GO-COOH enhanced the inhibitory effect, while uncharged polymer-modified GO-PEG weakened the inhibitory effect. The inhibitory effect of the inhibitors increased with the increase of surface charge density. The difference in inhibitory effect between GO-PEI and GO-COOH was due to the different electrostatic interactions between inhibitors and insulin, and the different inhibition mechanisms. In addition, inhibitors mainly interact with insulin during the nucleation phase to hinder insulin fibrillation. The charge modifications of graphene oxide enhanced the inhibitory effect on insulin fibrillation based on electrostatic interactions, which will provide new thoughts for the development of anti-amyloid fibrillation drugs.

On demand regulation of blood glucose level by biocompatible oxidized starch-Con A nanogels for glucose-responsive release of exenatide

Diabetes mellitus is a long-term chronic disease characterized by abnormal high level blood glucose (BG). An artificial closed-loop system that mimics pancreatic β-cells and releases insulin on demand has potential to improve the therapeutic efficiency of diabetes. Herein, a lectin Concanavalin A modified oxidized starch nanogel was designed to regulate glucose dynamically according to different glucose concentrations. The nanogels were formed by double cross-linking the Concanavalin A and glucose units on oxidized starch via specific binding and amide bonds to achieve the high drug loading and glucose responsiveness. The results showed that oxidized starch nanogels prolonged the half-life of antidiabetic peptide drug exenatide and released it in response to high BG concentrations. It could absorb BG at a high level and maintain glucose homeostasis. Besides, the oxidized starch nanogels performed well in recovering regular BG level from hyperglycemia state and maintaining in euglycemia state that fitted in a biological rhythm. In addition, the nanogels showed high biocompatibility in vivo and could improve plasma half-life and therapeutic efficacy of exenatide. Overall, the nanogels protected peptide drugs from degradation in plasma as a glucose-responsive platform showing a high potential for peptide drugs delivery and antidiabetic therapy.

Recent Advances in Glucose Responsive Insulin Delivery Systems: Novel Hydrogels and Future Applications

Over the past several decades, there have been major advancements in the field of glucose sensing and insulin delivery for the treatment of type I diabetes mellitus. The introduction of closed-loop insulin delivery systems that deliver insulin in response to specific levels of glucose in the blood has shifted significantly the research in this field. These systems consist of encapsulated glucose-sensitive components such as glucose oxidase or phenylboronic acid in hydrogels, microgels or nanoparticles. Since our previous evaluation of these systems in a contribution in 2004, new systems have been developed. Important improvements in key issues, such as consistent insulin delivery over an extended period of time have been addressed. In this contribution, we discuss recent advancements over the last 5 years and present persisting issues in these technologies that must be overcome in order for these systems to be applicable in patients.

Metabolic intervention liposome for targeting glutamine-addiction of breast cancer

The growth and rapid proliferation of tumor cells depend on both glycolysis and glutamine metabolism, leading to metabolic compensation. Here, dual inhibition on the metabolic plasticity by Glucose oxidase and Telaglenastat loaded liposome (Lip@GOx&Tel) were studied for intervening metabolic pathway on energy and material against breast cancer. Lip@GOx&Tel targeting inhibited the two nutrient supply mechanisms employed by tumor cells, reducing the supply of ATP production and biosynthesis precursors essential necessary for tumor, thereby eliciting anti-tumor and anti-metastasis effect. Meanwhile, Lip@GOx&Tel ingeniously amplify the therapeutic effect by up-regulating ROS and down-regulating GSH to disrupt redox homeostasis, thus resulting in inspiring 82% tumor suppression rate on 4 T1 tumor model. Moreover, our study solved the limitation of combination between protein drugs and small molecule drugs in vivo by using liposome nanoparticles with clinical translation value. In short, this work provides a unique perspective of nanomedicine for treating diseases from metabolic intervention.

Interactions between Nanoparticles and Intestine

The use of nanoparticles (NPs) has surely grown in recent years due to their versatility, with a spectrum of applications that range from nanomedicine to the food industry. Recent research focuses on the development of NPs for the oral administration route rather than the intravenous one, placing the interactions between NPs and the intestine at the centre of the attention. This allows the NPs functionalization to exploit the different characteristics of the digestive tract, such as the different pH, the intestinal mucus layer, or the intestinal absorption capacity. On the other hand, these same characteristics can represent a problem for their complexity, also considering the potential interactions with the food matrix or the microbiota. This review intends to give a comprehensive look into three main branches of NPs delivery through the oral route: the functionalization of NPs drug carriers for systemic targets, with the case of insulin carriers as an example; NPs for the delivery of drugs locally active in the intestine, for the treatment of inflammatory bowel diseases and colon cancer; finally, the potential concerns and side effects of the accidental and uncontrolled exposure to NPs employed as food additives, with focus on E171 (titanium dioxide) and E174 (silver NPs).

Glucose and H2O2 Dual-Responsive Nanocomplex Grafted with Insulin Prodrug for Blood Glucose Regulation

Although "closed-loop" smart insulin delivery systems have been extensively investigated, the majority of them suffer from low insulin loading efficiency and slow glucose response. Here, we constructed a novel nanocomplex (NC), which was prepared by electrostatic interaction between negatively charged insulin prodrug nanoparticles (NPs) and positively charged polycaprolactone-polyethylenimine (PCL-PEI) micelles. The insulin prodrug was linked to acetalated dextran (AD) via borate ester bonds to form IAD NPs, and glucose oxidase (GOx) was encapsulated in PCL-PEI micelles. The NC was negatively charged with a high insulin grafting rate (0.473 mg/mg), and in vitro experiments revealed that IAD was sensitive to hyperglycemia and H₂O₂, whereas GOx significantly improved the response to glucose by altering the microenvironment to promote sustained insulin release. Furthermore, compared with free insulin and IAD NPs, subcutaneously injected NCs in diabetic rats had long-term hypoglycemic effects, showing excellent biocompatibility in vitro and in vivo, which had good potential in insulin self-regulation delivery.