Understanding mucus modulation behavior of chitosan oligomers and dextran sulfate combining light scattering and calorimetric observations.

This study reports the fundamental understanding of mucus-modulatory strategies combining charged biopolymers with distinct molecular weights and surface charges. Here, key biophysical evidence supports that low-molecular-weight (Mw) polycation chitosan oligosaccharides (COSs) and high-Mw polyanion dextran sulfate (DS) exhibit distinct thermodynamic signatures upon interaction with mucin (MUC), the main protein of mucus. While the COS â†’ MUC microcalorimetric titrations released ~14 kcal/mol and ~60 kcal/mol, the DS â†’ MUC titrations released ~1200 and ~1450 kcal/mol at pH of 4.5 and 6.8, respectively. The MPT-2 titrations of COS â†’ MUC and DS â†’ MUC indicated a greater zeta potential variation at pH = 4.5 (relative variation = 815 % and 351 %, respectively) than at pH = 6.8 (relative variation = 282 % and 136 %, respectively). Further, the resultant binary (COS-MUC) and ternary (COS-DS-MUC) complexes showed opposite behavior (aggregation and charge inversion events) according to the pH environment. Most importantly, the results indicate that electrostatics could not be the driving force that governs COS-MUC interactions. To account for this finding, we proposed a two-level abstraction model. Macro features emerge collectively from individual interactions occurring at the molecular level. Therefore, to understand the outcomes of mucus modulatory strategy based on charged biopolymers it is necessary to integrate both visions into the same picture.

Dextran sulfate-based MMP-2 enzyme-sensitive SR-A receptor targeting nanomicelles for the treatment of rheumatoid arthritis.

Rheumatoid arthritis (RA) is an ordinarily occurring autoimmune disease with systemic inflammatory. Targeted drug delivery systems have many successful applications in the treatment of rheumatoid arthritis. In order to develop nanoparticles for targeted delivery of Celastrol (Cel) to rheumatoid arthritis and specific drug release, the dextran sulfate (DS) was modified as the targeting molecular by binding to the scavenger receptor of macrophage. The dextran-sulfate-PVGLIG-celastrol (DS-PVGLIG-Cel), named DPC, amphiphilic polymeric prodrug was synthesized and characterized. The resulting DPC@Cel micelles had the average size of 189.9 nm. Moreover, the micelles had ultrahigh entrapment efficiency (about 44.04%) and zeta potential of -11.91 mV. In the in vitro release study, due to the excessive production of matrix metalloproteinase-2 (MMP-2) at the inflammatory joint, the MMP-2 reactive peptide was used to crack in the inflammatory microenvironment to accelerate the release of Cel. The results have shown that the nanoparticles can effectively deliver Cel to activated macrophages and significantly improve the bioavailability. In vivo experiments showed that DPC@Cel have better anti-rheumatoid arthritis effects and lower systemic toxicity than free Cel. This study provided a new therapeutic strategy for the treatment of RA.

Barnase encapsulation into submicron porous CaCO3 particles: studies of loading and enzyme activity.

The present study focuses on the immobilization of the bacterial ribonuclease barnase (Bn) into submicron porous calcium carbonate (CaCO3) particles. For encapsulation, we apply adsorption, freezing-induced loading and co-precipitation methods and study the effects of adsorption time, enzyme concentration and anionic polyelectrolytes on the encapsulation efficiency of Bn. We show that the use of negatively charged dextran sulfate (DS) and ribonucleic acid from yeast (RNA) increases the loading capacity (LC) of the enzyme on CaCO3 particles by about 3-fold as compared to the particles with Bn itself. The ribonuclease (RNase) activity of encapsulated enzyme depends on the LC of the particles and transformation of metastable vaterite to stable calcite, as studied by the assessment of enzyme activities in particles.

New insights into physicochemical aspects involved in the formation of polyelectrolyte complexes based on chitosan and dextran sulfate.

Polyelectrolyte complexation is a technique based on interactions between polyelectrolytes of opposite charges driven by supramolecular interactions. Although many studies address the formation of polyelectrolyte complexes (PECs), few explore strategies and tools to select the best working conditions and are often based on empirical choices. This study evaluates the influence of pH, molecular weight, and polymeric proportion on the formation of PECs based on chitosan:dextran sulfate. In addition, it assesses the approaches that study the influence of pH on the zeta potential of polymeric dispersions as a tool in the design of PECs. Results showed that nanoparticles with an excess of polycation formed aggregates, while an excess of dextran sulfate reduced the size of the particles. The graph of zeta potential as a function of pH proved to be a promising tool in the choice of polymers and a better pH condition in the development of PECs.

Step-by-Step Design of New Theranostic Nanoformulations: Multifunctional Nanovectors for Radio-Chemo-Hyperthermic Therapy under Physical Targeting.

While investigating the possible synergistic effect of the conventional anticancer therapies, which, taken individually, are often ineffective against critical tumors, such as central nervous system (CNS) ones, the design of a theranostic nanovector able to carry and deliver chemotherapy drugs and magnetic hyperthermic agents to the target radiosensitizers (oxygen) was pursued. Alongside the original formulation of polymeric biodegradable oxygen-loaded nanostructures, their properties were fine-tuned to optimize their ability to conjugate therapeutic doses of drugs (doxorubicin) or antitumoral natural substances (curcumin). Oxygen-loaded nanostructures (diameter = 251 ± 13 nm, ζ potential = -29 ± 5 mV) were finally decorated with superparamagnetic iron oxide nanoparticles (SPIONs, diameter = 18 ± 3 nm, ζ potential = 14 ± 4 mV), producing stable, effective and non-agglomerating magnetic nanovectors (diameter = 279 ± 17 nm, ζ potential = -18 ± 7 mV), which could potentially target the tumoral tissues under magnetic driving and are monitorable either by US or MRI imaging.

Formulation and evaluation of injectable dextran sulfate sodium nanoparticles as a potent antibacterial agent.

The purpose of this study was to develop a novel nano antibacterial formulation of dextran sulfate sodium polymer. The dextran sulfate sodium (DSS) nanoparticles were formulated with gelation technique. The nanoparticles exhibited significant physicochemical and effective antibacterial properties, with zeta potential of - 35.2 mV, particle size of 69.3 z d nm, polydispersity index of 0.6, and percentage polydispersity of 77.8. The DSS nanoparticles were stable up to 102 °C. Differential scanning calorimetry revealed an endothermic peak at 165.77 °C in 12.46 min, while XRD analysis at 2θ depicted various peaks at 21.56°, 33.37°, 38.73°, 47.17°, 52.96°, and 58.42°, indicating discrete nanoparticle formation. Antibacterial studies showed that the DSS nanoparticles were effective against Gram-positive and Gram-negative bacteria. The minimum inhibitory concentrations of DSS nanoparticles for Bacillus subtilis (B. subtilis), Staphylococcus aureus (S. aureus), Streptococcus pyogenes (S. pyogenes), Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa), Klebsiella pneumoniae (K. pneumoniae) and Proteus vulgaris (P. vulgaris) were 150, 200, 250, 150, 200, 250, 250 µg/mL, respectively. The antibacterial effects of DSS nanoparticles were in the order E. coli (26 ± 1.2 mm) at 150 µg/mL > S. pyogenes (24.6 ± 0.8 mm) at 250 µg/mL > B. subtilis (23.5 ± 2 mm) at 150 µg/mL > K. pneumoniae (22 ± 2 mm) at 250 µg/mL > P. aeruginosa (21.8 ± 1 mm) at 200 µg/mL > S. aureus (20.8 ± 1 mm) at 200 µg/mL > P. vulgaris (20.5 ± 0.9 mm) at 250 µg/mL. These results demonstrate the antibacterial potency of DSS injectable nanoparticles.

Cerium oxide nanoparticles acts as a novel therapeutic agent for ulcerative colitis through anti-oxidative mechanism.

BACKGROUND: Cerium (IV) oxide (CeO2) exhibit anti-inflammatory activity via scavenge free radicals and decreasing the oxygen species (ROS) production. Here we aimed to exhibit the therapeutic effect of this nanoparticle in experimental colitis models. METHODS: Cerium oxide nanoparticles (CeONPs) were synthesized via using UiO-66 as a precursor. We used dextran sodium sulfate (DSS) to induce colitis in experimental models to investigate the anti-inflammatory effect of CeONPs. Colitis models are divided into four groups to receive the treatment, including control, colitis, cerium oxide, and sulfasalazine. We evaluated the therapeutic effects of CeONPs for the increased colitis clinical symptoms and attenuated the histological damage to colon tissue in colitis. RESULT: This nanoparticle was significantly able to reduce the clinical symptoms of colitis. Moreover, CeONPs can enhance the disease activity index such as body lose weight, diarrhea, rectal bleeding, colon length, and spleen weight. Moreover, CeONPs showed a significant reduction in the histological characteristics of the colitis models. CONCLUSION: These results suggest that CeONPs can be considered as promising therapeutic agents in treating the ulcerative colitis.

Nanoparticle-Based Rifampicin Delivery System Development.

The alkaline milieu of chronic wounds severely impairs the therapeutic effect of antibiotics, such as rifampicin; as such, the development of new drugs, or the smart delivery of existing drugs, is required. Herein, two innovative polyelectrolyte nanoparticles (PENs), composed of an amphiphilic chitosan core and a polycationic shell, were synthesized at alkaline pH, and in vitro performances were assessed by 1H NMR, elemental analysis, FT-IR, XRD, DSC, DLS, SEM, TEM, UV/Vis spectrophotometry, and HPLC. According to the results, the nanostructures exhibited different morphologies but similar physicochemical properties and release profiles. It was also hypothesized that the simultaneous use of the nanosystem and an antioxidant could be therapeutically beneficial. Therefore, the simultaneous effects of ascorbic acid and PENs were evaluated on the release profile and degradation of rifampicin, in which the results confirmed their synergistic protective effect at pH 8.5, as opposed to pH 7.4. Overall, this study highlighted the benefits of nanoparticulate development in the presence of antioxidants, at alkaline pH, as an efficient approach for decreasing rifampicin degradation.

Therapeutic plasma exchange and dextran-sulfate plasma adsorption as extracorporeal treatments of extremely preterm preeclampsia with fetal growth restriction.

AIM: To evaluate effectiveness and safety of therapeutic plasma exchange (TPE) and dextran-sulfate plasma adsorption (DSA) for extracorporeal removal of soluble Fms-like tyrosine kinase-1 (sFlt-1) as part of expectant management of preeclampsia at extremely preterm gestational age. METHODS: Retrospective case series of six patients with preeclampsia at <28 weeks of gestation, treated with DSA or TPE. Laboratory results, clinical characteristics and neonatal outcomes were collected from charts and National Perinatal Information System. RESULTS: Fetal growth restriction (FGR) was diagnosed in all cases. Pregnancy was prolonged for a median of 14 (range 5-74) days from admission and 10 (3-73) days from first apheresis. A mixed effects model showed a decrease in sFlt-1 and sFlt-1/PlGF ratio during DSA/TPE (significant effect of time [before/after]), which was comparable between DSA and TPE (no effect of procedure type). Median absolute reduction in sFlt-1 was 42% (inter-quartile range [IQR] 13%-57%) during DSA and 34% (16%-40%) during TPE; for sFlt-1/PlGF ratio it was 29% (22%-36%) and 38% (29%-42%), respectively. All procedures were well tolerated by fetuses. Anaphylactoid reaction, often with angioedema, occurred in 4/6 patients undergoing DSA and was attributed to bradykinin activation. One patient developed wound hematoma after cesarean section, possibly attributed to depletion coagulopathy. CONCLUSIONS: As potential novel treatment of early preeclampsia, a non-selective and widely available TPE was comparable to DSA regarding sFlt-1 reduction but was associated with fewer side-effects. Both seem to allow maternal stabilization and pregnancy prolongation even when early preeclampsia is complicated by FGR.

Modulating the in vitro gastric digestion of heat-induced beta-lactoglobulin aggregates: Incorporation with polysaccharide.

Three heat-induced protein aggregates, beta-lactoglobulin fibrils (BLGF), nanoparticles (BLGN), and worm-like aggregates (BLGW) were chosen to probe the effect of disulfide bond and surface hydrophobicity on their gastric digestion behavior. Furthermore, the effect of polysaccharide (dextran sulfate sodium, DSS) on the digestion behavior of the protein aggregates was investigated. Results showed that disulfide bond had a mild restraint on the digestion extent (maximum up to 4.65%), especially when its content was below 1 mol/mol, while the surface hydrophobicity had a stronger influence (up to 8.96%), and there is definitive positive linear relationship between the surface hydrophobicity and the digestion extent. When incorporated with DSS, both the disulfide bond content and surface hydrophobicity of the aggregates decreased, consequently, and the digestion was impeded, confirming the stronger effect from the surface hydrophobicity. The digestion extent of the heat-induced protein aggregates could be modulated linearly by incorporation of polysaccharide.

Three-Dimensional Quantitative Imaging of Native Microbiota Distribution in the Gut.

Owing to the challenges to acquire detailed spatial information of gut bacteria in situ, three-dimensional (3D) microbiota distributions in the gut remain largely uncharted. Here, we propose a tissue clearing-based and D-amino acid labeling-facilitated (TiDaL) strategy that combines a novel microbiota in vivo labeling protocol, CUBIC-based tissue clearing and whole-mount tissue imaging, to achieve 3D imaging of indigenous gut microbiota. We demonstrate high-resolution 3D acquisition of their biogeography in different gut sections, and present quantitative spatial details in relation to the host epithelium. We unexpectedly observe microbiota in the small intestine crypts, which were thought to be bacteria-free. Significant bacterial overgrowth in the first two-thirds of the small intestine is detected in an enteritis model. We expect that this quantitative 3D imaging strategy for native gut microbiota will provide insightful information into the host-microbiota interactions.

A homogeneous assay to determine high-density lipoprotein subclass cholesterol in serum.

Existing methods to measure high-density lipoprotein cholesterol (HDL-C) subclasses (HDL2-C and HDL3-C) are complex and require proficiency, and thus there is a need for a convenient, homogeneous assay to determine HDL-C subclasses in serum. Here, cholesterol reactivities in lipoprotein fractions [HDL2, HDL3, low-density lipoprotein (LDL), and very-low-density lipoprotein (VLDL)] toward polyethylene glycol (PEG)-modified enzymes were determined in the presence of varying concentrations of dextran sulfate and magnesium nitrate. Particle sizes formed in the lipoprotein fractions were measured by dynamic light scattering. We optimized the concentrations of dextran sulfate and magnesium nitrate before assay with PEG-modified enzymes to provide selectivity for HDL3-C. On addition of dextran sulfate and magnesium nitrate, the sizes of particles of HDL2, LDL, and VLDL increased, but the size of HDL3 fraction particles remained constant, allowing only HDL3-C to participate in coupled reactions with the PEG-modified enzymes. In serum from both healthy volunteers and patients with type 2 diabetes, a good correlation was observed between the proposed assay and ultracentrifugation in the determination of HDL-C subclasses. The assay proposed here enables convenient and accurate determination of HDL-C subclasses in serum on a general automatic analyzer and enables low-cost routine diagnosis without preprocessing.

Dual Transport of Active Substances with a Layer-by-Layer-Based Drug Delivery System to Terminate Inflammatory Processes.

Conventional therapies for chronic inflammation with high dose application of active agents are often accompanied with severe side effects so that other therapeutical strategies shall be developed to be less physically demanding but still highly efficient. Locally applied Layer-by-Layer (LbL) microcarriers transporting a low, but efficient dosage of active agents directly into the inflamed tissue offer a gentle therapy option. Here, the inhibition of highly degradative enzyme human neutrophile elastase (HNE) is adressed, which is produced and secreted by neutrophile granulocytes (PMNs) in the progress of inflammation. The protected transport and release of its natural inhibitor α1-antitrypsin (AT) as a constituent of the microcarrier's biopolymer multilayer allows for an efficient inhibition of extra- and intracellular elastase. The HOCl scavenger molecule cefoperazone, which preserves AT activity, as an additional multilayer constituent induces a much higher efficacy of the inhibitor. The successful assembly of both agents in different layers of the multilayer and the subsequent HNE inhibition in PMNs is investigated. The parallel application of cefoperazone leads to an enhanced inhibitory effect even with reduced AT amount and reduced carrier:cell ratio. It is demonstrated that the modular assembly strategy of LbL carriers allows for efficient synergistic effect of active agents in inflammatory process.

Chitosan-coated nanodiamonds: Mucoadhesive platform for intravesical delivery of doxorubicin.

Nanodiamonds (NDs) are an emerging delivery system with a massive surface area qualifying them for efficient loading with various drugs. However, NDs easily scavenge ions upon mixing with physiological media leading to rapid aggregation. Herein, chitosan was employed to endue steric stabilization to NDs and confer adhesiveness to the particles improving their retention in the urinary bladder. The effect of chitosan molecular weight and pH on the particle size and surface charge of chitosan-coated doxorubicin-loaded NDs (Chi-NDX) was investigated. Selected formula exhibited high drug loading efficiency (>90 %), small particle size (<150 nm), good colloidal stability, acid-favored drug release but limited stability in cell culture media. After further stabilization with TPP or dextran sulfate, selected TPP-treated formula displayed more potent cytotoxic effect compared with free doxorubicin and uncoated nanoparticles, and higher drug retention in ex vivo bovine bladder. Therefore, TPP-Chi-NDX is suggested as a promising system for mucosal anticancer delivery.

Ternary nanoparticle complex of antibiotic, polyelectrolyte, and mucolytic enzyme as a potential antibiotic delivery system in bronchiectasis therapy.

Antibiotic-polyelectrolyte nanoparticle complex (or nanoplex in short) has been recently demonstrated as a superior antibiotic delivery system to the native antibiotic in bronchiectasis therapy owed to its ability to overcome the lung's mucus barrier and generate high localized antibiotic exposure in the infected sites. The present work aimed to further improve the mucus permeability, hence the antibacterial efficacy of the nanoplex, by incorporating mucolytic enzyme papain (PAP) at the nanoplex formation step to produce PAP-decorated antibiotic-polyelectrolyte nanoplex exhibiting built-in mucolytic capability. Ciprofloxacin (CIP) and dextran sulfate (DXT) were used as the models for antibiotics and polyelectrolyte, respectively. The results showed that the PAP inclusion had minimal effects on the physical characteristics, preparation efficiency, and dissolution of the CIP-DXT nanoplex. The optimal CIP-(DXT-PAP) nanoplex exhibited size and zeta potential of approximately 200 nm and -50 mV with CIP and PAP payloads of 60% and 32% (w/w), respectively. The nanoplex was prepared at high efficiency with larger than 80% CIP and PAP utilization rates. The CIP-(DXT-PAP) nanoplex exhibited tenfold improvement in the mucus permeability compared to its CIP-DXT nanoplex counterpart, resulting in the former's superior bactericidal activity against clinical Pseudomonas aeruginosa biofilm in the presence of mucus barrier. A trade-off, nevertheless, existed between antibacterial efficacy and cytotoxicity towards human lung epithelium cells upon the incorporation of PAP above a certain concentration threshold. Therefore, the optimal dosing of the CIP-(DXT-PAP) nanoplex must be carefully determined.

Polyelectrolyte three layer nanoparticles of chitosan/dextran sulfate/chitosan for dual drug delivery.

In this work, dual drug loaded in chitosan/dextran sulfate/chitosan (CS/DEX/CS) nanoparticles was synthesized by layer-by-layer (LBL) self-assembly technique for use in anti-cancer drug delivery. The nanoparticles were characterized in terms of particle size, zeta-potential, encapsulation efficiency and morphology (SEM and TEM). The in vitro release of the dual drugs, inner PTX and outer 5-Fu, from the CS-PTX/EX/CS-5Fu nanoparticles with different numbers of CS and DEX layers and different PBS was characterized. The results revealed that the pH-sensitive dual drug loaded nanoparticles exhibited a controlled release profile, and the release mechanism followed Two-phase kinetic model for PTX and Higuchi model for 5-Fu. Subsequently the cytotoxicity of nanoparticles was evaluated against HepG2 cells using MTT and apoptosis assay, resulting in synergistic effects between dual drugs and enhanced inhibition to cancer cells. Cellular uptake studies demonstrated efficient internalization of PTX and 5-Fu in HepG2 cells. Therefore the dual drug loaded CS/DEX/CS nanoparticles had good prospects for the biomedical delivery application.

Antibiotic loading and development of antibacterial capsules by using porous CaCO3 microparticles as starting material.

Porous calcium carbonate (CaCO3) particles have been shown to be highly advantageous for biological applications, mainly due to their large surface area and their stability in physiological media. Also, developing appropriate antibacterial materials presenting the benefits of non-formation of harmful compounds is of major interest. Two characteristics of CaCO3 particles were investigated herein: (i) antibiotic-loading capacity and (ii) the possibility of using CaCO3 particles as a template for the fabrication of biocapsules presenting inherent antibacterial capacity. The particles were tested against two representative pathogenic bacteria (Staphylococcus aureus and Escherichia coli). On one hand, a method for antibiotic (namely penicillin, ampicillin and ciprofloxacin) loading inside calcium carbonate particles was developed and antibacterial activity was investigated. Encapsulation efficiency and loading content were 95% and 5%, respectively. We showed that antibiotics prevented bacterial growth within 2 h, with no evidence of bacterial regrowth within 16 h; bactericidal effects were also observed. On the other hand, the self-assembly of charged polysaccharides, namely chitosan (chi+) and dextran sulfate (dex-), were assessed on calcium carbonate microparticles used as a sacrificial matrix. During bacterial growth in a liquid medium, an inhibitory effect of these particles was observed, i.e. Staphylococcus aureus (Gram-positive) (from 16.3% to 48.8% for (chi+/dex-)n-chi+ coated CaCO3 materials and from 41.9% to 93.0% for (chi+/dex-)n-chi+ capsules) and Escherichia coli (Gram-negative) (from 18.2% to 45.5% for (chi+/dex-)n-chi+ coated CaCO3 materials and from 40.0% to 89.1% for (chi+/dex-)n-chi+ capsules). Staining with acridine orange highlighted the bactericidal effect of the designed particles. These findings demonstrate the excellent potential of using calcium carbonate particles in antibiotic therapy as a starting point for the development of smart materials.

Flash Fabrication of Orally Targeted Nanocomplexes for Improved Transport of Salmon Calcitonin across the Intestine.

Salmon calcitonin (sCT) is a potent calcium-regulating peptide hormone and widely applied for the treatment of some bone diseases clinically. However, the therapeutic usefulness of sCT is hindered by the frequent injection required, owing to its short plasma half-life and therapeutic need for a high dose. Oral delivery is a popular modality of administration for patients because of its convenience to self-administration and high patient compliance, while orally administered sCT remains a great challenge currently due to the existence of multiple barriers in the gastrointestinal (GI) tract. Here, we introduced an orally targeted delivery system to increase the transport of sCT across the intestine through both the paracellular permeation route and the bile acid pathway. In this system, sCT-based glycol chitosan-taurocholic acid conjugate (GC-T)/dextran sulfate (DS) ternary nanocomplexes (NC-T) were produced by a flash nanocomplexation (FNC) process in a kinetically controlled mode. The optimized NC-T exhibited well-controlled properties with a uniform and sub-60 nm hydrodynamic diameter, high batch-to-batch reproducibility, good physical or chemical stability, as well as sustained drug release behaviors. The studies revealed that NC-T could effectively improve the intestinal uptake and permeability, owing to its surface functionalization with the taurocholic acid ligand. In the rat model, orally administered NC-T showed an obvious hypocalcemia effect and a relative oral bioavailability of 10.9%. An in vivo assay also demonstrated that NC-T induced no observable side effect after long-term oral administration. As a result, the orally targeted nanocomplex might be a promising candidate for improving the oral transport of therapeutic peptides.

Complexes of glucose oxidase with chitosan and dextran possessing enhanced stability.

In this study, the different mole ratios of glucose oxidase/chitosan/dextran-aldehyde and glucose oxidase/chitosan/dextran-sulfate complexes were synthesized. The modification of glucose oxidase by non-covalent complexation with dextran and chitosan in different molar ratios was studied in order to increase the enzyme activity. The enzyme/polymer complexes obtained were investigated by UV spectrophotometer and dynamic light scattering. Activity determination of synthesized complexes and free enzyme were performed at a temperature range. The best results were obtained by Cchitosan/Cdextran-aldehyde = 10/1 ratio and Cchitosan/Cdextran-sulfate = 1/5 ratio that were used in thermal stability, shelf life, salt stress, and ethanol effect experiments. The results demonstrated that both complexes were thermally stable at 60 °C and had superior storage stability compared to the free glucose oxidase. Complexes showed higher enzymatic activity than free enzyme in the organic solvent environment using 10% ethanol. The complexes were resistant to salt stress containing 0.1 M NaCl or CaCl2. The particle size distribution results of the triple complex evaluated the complexation of the chitosan, dextran derivative, and glucose oxidase. The average size of the triple complex in diameter was found to be 325.8 ± 9.3 nm. Overall findings suggest that the complexes of glucose oxidase, chitosan, and dextran showed significant enhancement in the enzyme activity.

Prolonged melittin release from polyelectrolyte-based nanocomplexes decreases acute toxicity and improves blood glycemic control in a mouse model of type II diabetes.

Gating modifier toxins (GMTs) from animal venom have shown great potential in controlling blood glucose levels in type II diabetes (T2D), but their high acute toxicity and quick clearance in the body hamper their potential therapeutic use. Inspired by their highly positive charge, we have developed a nanocomplex system based on polyelectrolytes, in which strong interactions form between positively charged GMTs and negatively charged dextran sulfate (DS). Using melittin as a model GMT and adapting flash nanocomplexation (FNC) technology for complex preparation, uniform nanocomplexes (polydispersity index: ~0.1) with high melittin encapsulation efficiency (~100%), high payload capacity (~30%), and tunable release profiles were formulated. In contrast to the high acute liver toxicity and low survival rate (60% after 8 days) observed after a single intraperitoneal (i.p.) injection of 3 mg/kg free melittin, melittin-loaded nanocomplexes displayed improved safety (100% survival after 8 days) due to prolonged melittin release. In a mouse model of T2D, a single i.p. injection of nanocomplexes decreased the blood glucose level to 12 mmol/L within 12 h and maintained it within the therapeutic range (<15 mmol/L) for 48 h. In addition, body weight decreased following treatment. This GMT/DS binary system shows great promise due to its simple components, facile preparation method, and enhanced potential druggability, including a decreased dosing frequency, decreased acute toxicity, and improved pathological indicators.