Cholic acid modified N-(2-hydroxy)-propyl-3-trimethylammonium chitosan chloride for superoxide dismutase delivery

A novel highly thermostable and stress resistant ROS scavenging metalloprotein from Paenibacillus

Reactive oxygen species (ROS) are unstable metabolites produced during cellular respiration that can cause extensive damage to the body. Here we report a unique structural metalloprotein called RSAPp for the first time, which exhibits robust ROS-scavenging activity, high thermostability, and stress resistance. RSAPp is a previously uncharacterized DUF2935 (domain of unknown function, accession number: cl12705) family protein from Paenibacillus, containing a highly conserved four-helix bundle with binding sites for variable-valence metal ions (Mn2+/Fe2+/Zn2+). Enzymatic characterization results indicated that RSAPp displays the functionality of three different antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD). In particular, RSAPp exhibits a significant SOD-like activity that is remarkably effective in eliminating superoxide radicals (up to kcat/KM = 2.27 × 1011 mol-1 s-1), and maintains the catalytical active in a wide range of temperatures (25-100 °C) and pH (pH 2.0-9.0), as well as resistant to high temperature, alkali and acidic pH, and 55 different concentrations of detergent agents, chemical solvents, and inhibitors. These properties make RSAPp an attractive candidate for various industrial applications, including cosmetics, food, and pharmaceuticals.

Amphiphilic Chitosan Bearing Double Palmitoyl Chains and Quaternary Ammonium Moieties as a Nanocarrier for Plasmid DNA

Amphiphilic chitosan, bPalm-CS-HTAP, having N-(2-((2,3-bis(palmitoyloxy)propyl)amino)-2-oxoethyl) (bPalm) groups as double hydrophobic tails and O-[(2-hydroxyl-3-trimethylammonium)] propyl (HTAP) groups as hydrophilic heads was synthesized and evaluated for its self-assembly properties and potential as a gene carrier. The degree of bis-palmitoyl group substitution (DS _bPalm) and the degree of quaternization (DQ) were approximately 2 and 56%, respectively. bPalm-CS-HTAP was found to assemble into nanosized spherical particles with a hydrodynamic diameter (D _H) of 265.5 ± 7.40 nm (PDI = 0.5) and a surface charge potential of 40.1 ± 0.04 mV. bPalm-CS-HTAP condensed the plasmid pVAX1.CoV2RBDme completely at a bPalm-CS-HTAP:pDNA ratio of 2:1. The self-assembled bPalm-CS-HTAP/pDNA complexes could enter HEK 293A and CHO cells and enabled gene expression at negligible cytotoxicity compared to commercial PEI (20 kDa). These results suggested that bPalm-CS-HTAP can be used as a promising nonviral gene carrier.

Antioxidant Enzymes Sequestered within Lipid-Polymer Hybrid Nanoparticles for the Local Treatment of Inflammatory Bowel Disease

The local treatment of inflammatory bowel disease (IBD) by enzyme therapeutics is challenging owing to hostile environments in the gastrointestinal tract, leading to the hydrolysis and enzymatic degradation of labile proteins. In this study, safe and efficient local drug delivery systems were developed by antioxidant superoxide dismutase (SOD) sequestered within lipid-polymer hybrid nanoparticles through sequential self-assembly processes. Interestingly, we found that the sequestered SOD exhibited long-term enzymatic stability and comparable biological activity to the enzymes in the native form, probably owing to particle encapsulation providing a physical barrier to prevent the enzymolysis of proteins. We demonstrated that nanoparticle-based local drug delivery systems showed excellent mucus-penetrating ability and inflammation-targeting properties, owing to the particle surface with a poly(ethylene glycol) (PEG) coating and folate functionalization, thus improving mucosal retention time and drug delivery efficiency within the colorectal region. Furthermore, SOD-containing lipid-polymer hybrid nanoparticles could effectively mitigate inflammatory responses by regulating the secretion of inflammation-associated cytokines, thus increasing therapeutic outcomes in colitis mice through intrarectal administration. The findings indicated that antioxidant enzymes sequestered within lipid-polymer hybrid nanoparticles might be potential enzyme therapeutics for the local treatment of some inflammatory diseases in the near future.

Fabrication and characterization of oil-in-water pickering emulsions stabilized by ZEIN-HTCC nanoparticles as a composite layer

In this work, the ZEIN-HTCC nanoparticles formed by zein and N-(2-hydroxy)propyl-3-trimethylammonium chitosan chloride (HTCC) were used as stabilizers to prepare oil-in-water (O/W) Pickering emulsions. The preparation conditions including shearing time, volume fraction of corn oil, mass ratio of ZEIN:HTCC and total concentration of ZEIN-HTCC of emulsions were optimized by measuring the droplet size, zeta potential, PDI and surface tension of emulsions. The ZEIN-HTCC emulsions are stable at the pH range of 4-9 and in the low salt ion concentrations up to 0.2 mol L^-1, and can keep stable up to 21 d during low temperature storage. Fourier transform infrared spectroscopy (FTIR), the confocal laser scanning microscope (CLSM) and scanning electron microscopy (SEM) were used to analyze the interaction between emulsion components, revealing that zein and HTCC form a composite layer by flocculation to adsorb on the surface of oil droplets, thus preventing emulsion droplets from aggregation. This novel, long-term stable, surfactant-free, and edible zein-based Pickering emulsion could be used as potential carriers for lipophilic nutrients delivery.

ATP/Hyals dually responsive core-shell hyaluronan/chitosan-based drug nanocarrier for potential application in breast cancer therapy

The stability of self-assembled drug nanocarriers during blood circulation and the controlled intracellular drug delivery are two challenges in cancer therapy. In this paper, we constructed an adenosine triphosphate (ATP)/hyaluronidase(Hyals) dually responsive core-shell hyaluronan/chitosan-based drug nanocarrier for breast cancer therapy, using SNX-loaded 3-fluoro-4-carboxyphenylboronic acid-conjugated quaternary ammonium chitosan nanoparticles (SNX@HTCC-FPBA NPs) as the core and crosslinked polyethylene glycol-/methacrylate-modified hyaluronic acid (mHA-PEG) as the shell. The formed SNX@HTCC-FPBA/mHA-PEG NPs were stable against salt ion strength, pH values and human plasma mimicking the bloodstream, but ATP/Hyals dually sensitive with a drug delivery of 85% within 48 h in the mimicking intracellular environment of breast cancer cells. These nanoparticles showed a low hemolysis of less than 3%, a high resistance to bovine serum albumin adsorption of 0.06 mg/mg, and an efficient internalization by two breast cancer cell lines (MCF-7 and MDA-MB-453). The cell culture indicated that they were friendly to human skin fibroblasts, but presented a close IC₅₀ value to SNX for MCF-7 (0.14 μg mL^-1) and MDA-MB-453 (0.05 μg mL^-1) at 48 h, respectively. Thus, SNX@HTCC-FPBA/mHA-PEG NPs were potential drug nanocarriers for breast tumor therapy.

Strategies to expand the therapeutic potential of superoxide dismutase by exploiting delivery approaches

The overproduction of free radicals can cause oxidative-stress damage to a range of biomolecules, and thus potentially contribute to several pathologies, from neurodegenerative disorders to cardiovascular diseases and metabolic disorders. Endogenous antioxidant enzymes, such as superoxide dismutase (SOD), play an important role in diminishing oxidative stress. SOD supplementation could therefore be an effective preventive strategy to reduce the risk of free-radical overproduction. However, the efficacy of SOD administration is hampered by its rapid clearance. Several different approaches to improve the bioavailability of SOD have been explored in recent decades. This review intends to describe the rationale that underlie the various approaches and chemical strategies that have led to the most recent advances in SOD delivery. This critical description includes SOD conjugates, SOD loaded into particulate carriers (micelles, liposomes, nanoparticles, microparticles) and the most promising and suitable formulations for oral delivery, with a particular emphasis on reports of preclinical/clinical results. Likely future directions are also considered and reported.

Phosphatidylserine targeting peptide-functionalized pH sensitive mixed micelles for enhanced anti-tumor drug delivery

In recent decades, targeted drug delivery systems (TDDS) have been widely used as an ideal method of improving therapeutic effects and reducing systemic side effects of chemotherapeutic agents. Historically, a handful of methods have been developed to further improve the targeting ability of delivery systems. Thus, in this study, two methods, taking advantage of tumor characteristics, were used for the creation of a multi-targeted delivery system. The first was the fabrication of pH-sensitive micelles, lending the ability to increase drug release by exploiting the acidic tumor environment. The second method was through utilization of the surface-exposed phosphatidylserine (PS) of tumors, which is normally found in the inner leaflet in healthy cells. Using PS as a target site, PS binding peptide (PSBP-6) was conjugated to pH-sensitive mixed micelles, (consisting of poly (ethylene glycol)-b-poly (D, L-lactide) (PEG-PDLLA) and poly (ethylene glycol)-b-poly (L-histidine) (PEG-PHIS)). After successful preparation of micelles, paclitaxel (PTX), a common chemotherapeutic agent, was selected to measure drug loading capacity and encapsulation efficiency, showing 7.9% and 83.5%, respectively. The in vitro release of PTX from mixed micelles at pH 5.0, 6.5, and 7.4 was 78.1, 56.8, and 51.4%, respectively, indicating acid-triggered drug release. The PSBP-6-modified, mixed micelles exhibited significantly enhanced in vitro cytotoxicity and demonstrated more efficient cellular uptake compared to unmodified mixed micelles in the HeLa cell line. Moreover, pharmacokinetic, in vivo biodistribution, and fluorescence imaging studies showed that PSBP-6-PEG-PDLLA/PEG-PHIS mixed micelles provide prolonged time in blood circulation and enhanced tumor accumulation. These results suggest that the use of PS as a novel targeting site is advantageous, and that these new multi-targeted mixed micelles show great potential for realization of broad prospects in the targeted treatment of tumors for chemotherapeutic delivery.

A Delivery System for Oral Administration of Proteins/Peptides Through Bile Acid Transport Channels

Proteins and peptides are poorly absorbed via oral administration because of the gastrointestinal tract environment and lysosomal digestion after apical endocytosis. A delivery system, consisting of a deoxycholic acid-conjugated nanometer-sized carrier, may enhance the absorption of proteins in the intestine via the bile acid pathway. Deoxycholic acid is first conjugated to chitosan. Liposomes are then prepared and loaded with the model drug insulin. Finally, the conjugates are bound to the liposome surface to form deoxycholic acid and chitosan conjugate-modified liposomes (DC-LIPs). This study demonstrates that DC-LIPs can promote the intestinal absorption of insulin via the apical sodium-dependent bile acid transporter, based on observing fluorescently stained tissue slices of the rat small intestine and a Caco-2 cell uptake experiment. Images of intestinal slices revealed that excellent absorption of DC-LIPs is achieved via apical sodium-dependent bile acid transporter, and a flow cytometry experiment proved that DC-LIPs are a highly efficient delivery carrier. Caco-2 cells were also used to study the lysosome escape ability of DC-LIPs. We learned from confocal microscopy photographs that DC-LIPs can protect their contents from being destroyed by the lysosome. Finally, according to pharmacokinetic analyses, insulin-loaded DC-LIPs show a significant hypoglycemic effect with an oral bioavailability of 16.1% in rats with type I diabetes.

Cellular Uptake and Intracellular Antioxidant Activity of Zein/Chitosan Nanoparticles Incorporated with Quercetin

In this work, zein/chitosan nanoparticles (ZCPs-Q) were developed for encapsulating quercetin to overcome its lower water solubility and instability, and to concomitantly enhance its cellular uptake and intracellular antioxidant activity. This strategy enhanced quercetin solubility 753.6 and 9.95 times in water and PBS (7.4), respectively, and quercetin encapsulated in ZCPs remained stable after UV irradiation and heat treatment. ZCPs-Q could significantly attenuate AAPH induced erythrocyte hemolysis through the inhibition of ROS generation. It restored intracellular antioxidant enzyme (SOD and GSH-Px) activities to normal levels and inhibited intracellular malondialdehyde (MDA) formation. Simultaneously, ZCPs-Q showed a strong antioxidant activity in HepG2 cells with an EC₅₀ value of 31.18 μg/mL, which was lower than free quercetin's 41.02 μg/mL. ZCPs enhanced the uptake efficiency of quercetin in Caco-2 cells, which contributed to the improvement of cellular antioxidant activities (CAA) evaluated with the CAA assay and AAPH-induced erythrocyte hemolysis assay. The designed route is particularly suitable for the encapsulation of water-insoluble nutraceuticals and for enhancing cell uptake and CAA.

Quaternized chitosan nanoparticles loaded with the combined attenuated live vaccine against Newcastle disease and infectious bronchitis elicit immune response in chicken after intranasal administration

Newcastle disease (ND) and infectious bronchitis (IB) are important diseases, which cause respiratory diseases in chickens, resulting in severely economic losses in the poultry industry. In this study, N-2-hydroxypropyl trimethyl ammonium chloride chitosan (N-2-HACC) and N,O-carboxymethyl chitosan (CMC) were synthesized as adjuvant and delivery carrier for vaccine antigens. N-2-HACC-CMC/NDV/IBV nanoparticles (NPs) (NDV/La Sota and IBV/H120 encapsulated in N-2-HACC-CMC NPs) and N-2-HACC-CMC/NDV-IBV NPs (the mixing of N-2-HACC-CMC/NDV NPs and N-2-HACC-CMC/IBV NPs in a ratio of 1:1) were prepared by the polyelectrolyte composite method, respectively. Both nanoparticles exhibited lower cytotoxicity and higher stability. Their bioactivities were maintained when they were stored at 37 °C for three weeks. Release assay in vitro showed that both NDV and IBV could be sustainably released from the nanoparticles after an initial burst release. In vivo immunization of chickens showed that N-2-HACC-CMC/NDV/IBV NPs or N-2-HACC-CMC/NDV-IBV NPs intranasally induced higher titers of IgG and IgA antibodies, significantly promoted proliferation of lymphocytes and induced higher levels of interleukine-2 (IL-2), IL-4 and interferon-γ (IFN-γ) than the commercially combined attenuated live vaccine did. This is the first study in the field of animal vaccines demonstrating that intranasal administration of chickens with antigens (NDV and IBV) encapsulated with chitosan derivative could induce humoral, cellular, and mucosal immune responses, which protected chickens from the infection of highly virulent NDV and IBV. This study indicated that N-2-HACC-CMC could be used as an efficient adjuvant and delivery carrier for further development of mucosal vaccines and drugs and could have an immense application potential in medicine.

Construction of a Fluorescent H₂O₂ Biosensor with Chitosan 6-OH Immobilized β-Cyclodextrin Derivatives

In the present work, a fluorescent H₂O₂ biosensor was constructed by encapsulating fluorescent probe Rhodamine B (RhmB) in the hydrophobic cavity of the cyclodextrin (β-CD) and immobilizing catalase (CAT) on the 2-NH₂ of chitosan (CTS) in a chitosan 6-OH immobilized β-cyclodextrin derivative (CTS-6-CD). The inclusion complex of CTS-6-CD to RhmB (CTS-6-CD-RhmB) was prepared by a solution method. Its structure and inclusion efficiency were determined by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and fluorescence spectroscopy (FL). CAT was immobilized on CTS-6-CD-RhmB to eventually form the functional membrane, CTS-6-CD-RhmB-CAT, via glutaraldehyde crosslinking, which was further characterized by FTIR and FL, and used as a H₂O₂ biosensor. The functional membrane was used to simultaneously oxidize and detect H₂O₂. The detection condition was optimized as pH 8, a reaction temperature of 25 °C, and an immobilized enzyme concentration of 2 × 10^-4 mol/L. The fluorescence response of the biosensor exhibited a good linear relationship with the concentration of H₂O₂ in the range of 20 mΜ-300 μM and the detection limit of 10^-8 mol/L.

Construction and Characterization of a Chitosan-Immobilized-Enzyme and β-Cyclodextrin-Included-Ferrocene-Based Electrochemical Biosensor for H₂O₂ Detection

An electrochemical detection biosensor was prepared with the chitosan-immobilized-enzyme (CTS-CAT) and β-cyclodextrin-included-ferrocene (β-CD-FE) complex for the determination of H₂O₂. Ferrocene (FE) was included in β-cyclodextrin (β-CD) to increase its stability. The structure of the β-CD-FE was characterized. The inclusion amount, inclusion rate, and electrochemical properties of inclusion complexes were determined to optimize the reaction conditions for the inclusion. CTS-CAT was prepared by a step-by-step immobilization method, which overcame the disadvantages of the conventional preparation methods. The immobilization conditions were optimized to obtain the desired enzyme activity. CTS-CAT/β-CD-FE composite electrodes were prepared by compositing the CTS-CAT with the β-CD-FE complex on a glassy carbon electrode and used for the electrochemical detection of H₂O₂. It was found that the CTS-CAT could produce a strong reduction peak current in response to H₂O₂ and the β-CD-FE could amplify the current signal. The peak current exhibited a linear relationship with the H₂O₂ concentration in the range of 1.0 × 10^-7-6.0 × 10^-3 mol/L. Our work provided a novel method for the construction of electrochemical biosensors with a fast response, good stability, high sensitivity, and a wide linear response range based on the composite of chitosan and cyclodextrin.

pH-Responsive Triblock Copolymeric Micelles Decorated with a Cell-Penetrating Peptide Provide Efficient Doxorubicin Delivery

This study developed novel triblock pH-responsive polymeric micelles (PMs) using cholic acid-polyethyleneimine-poly-L-arginine (CA-PEI-pArg) copolymers. PEI provided pH sensitivity, while the hydrophilic cell-penetrating pArg peptide promoted cellular PM internalization. The copolymers self-assembled into PMs in aqueous solution at above the critical micelle concentration (2.98 × 10^-7 M) and encapsulated doxorubicin in the core region, with a 34.2% (w/w) entrapment efficiency. PMs showed pH-dependent swelling, increasing in size by almost sevenfold from pH 7.4 to 5.0. Doxorubicin release was pH-dependent, with about 65% released at pH 5.0, and 32% at pH 7.4. Cellular uptake, assessed by confocal microscopy and flow cytometry, was enhanced by using doxorubicin-loaded CA-PEI-pArg PMs, as compared to free doxorubicin and DOX-loaded CA-PEI PMs. Moreover, 24-h incubation of these PMs with a human breast cancer cell line produced greater cytotoxicity than free doxorubicin. These results indicate that pH-responsive CA-PEI-pArg micelles could provide a versatile delivery system for targeted cancer therapy using hydrophobic drugs. Graphical of CA-PEI-pArg polymeric micelles as a pH-responsive drug delivery system.

Effective Enhancement of Hypoglycemic Effect of Insulin by Liver-Targeted Nanoparticles Containing Cholic Acid-Modified Chitosan Derivative

Liver is responsible for the balance of blood glucose level. In this study, cholic acid and N-(2-hydroxy)-propyl-3-trimethylammonium chloride modified chitosan (HTCC-CA) was used as a liver-targeted vehicle for insulin delivery. A novel approach was developed to effectively load insulin by mixing insulin and HTCC-CA in 50% ethanol and water mixed solvent at pH 2 and then dialysis against pH 7.4 phosphate buffer subsequently against water. The insulin-loaded HTCC-CA nanoparticles have an average diameter of 86 nm and insulin loading efficiency of 98.7%. Due to random distribution of the hydrophobic cholic acid groups in HTCC-CA, some of the cholic acid groups located on the nanoparticle surface. Compared with free insulin, the nanoparticles increased in vitro cellular uptake of insulin to 466%, and the nanoparticles accumulated in liver for more time after subcutaneous injection into mice. The therapy for diabetic rats displayed that the nanoparticles increased the pharmacological bioavailability of insulin to 475% relative to free insulin, and the nanoparticles could maintain the hypoglycemic effect for more than 24 h. This study demonstrates that the nanoparticles with cholic acid groups on their surface possess liver-targeted property and biocompatible insulin-loaded HTCC-CA nanoparticles can effectively enhance the hypoglycemic effect of insulin.

The conjugation of Cu/Zn superoxide dismutase (SOD) to O-(2-hydroxyl) propyl-3-trimethyl ammonium chitosan chloride (O-HTCC) enhances its therapeutic potential against radiation-induced oxidative damage

A novel polymer–enzyme conjugate, O-HTCC–SOD, was prepared to improve the therapeutic potential of SOD in vitro and in vivo.

Fabrication of zein/quaternized chitosan nanoparticles for the encapsulation and protection of curcumin

In this article, we report the successful assembly of nanoparticles (NPs) from a water-soluble chitosan (CS) derivative (N-(2-hydroxyl)propyl-3-trimethyl ammonium chitosan chloride, HTCC) and zein via a low-energy phase separation method.

Synthesis and rheological characterization of water-soluble glycidyltrimethylammonium-chitosan

In this study, chitosan (CS) grafted by glycidyltrimethylammonium chloride (GTMAC) to form GTMAC-CS was synthesized, chemically identified, and rheologically characterized. The Maxwell Model can be applied to closely simulate the dynamic rheological performance of the chitosan and the GTMAC-CS solutions, revealing a single relaxation time pertains to both systems. The crossover point of G' and G" shifted toward lower frequencies as the CS concentration increased but remained almost constant frequencies as the GTMAC-CS concentration increased, indicating the solubility of GTMAC-CS in water is good enough to diminish influence from the interaction among polymer chains so as to ensure the relaxation time is independent of the concentration. A frequency-concentration superposition master curve of the CS and GTMAC-CS solutions was subsequently proposed and well fitted with the experimental results. Finally, the sol-gel transition of CS is 8.5 weight % (wt %), while that of GTMAC-CS is 20 wt %, reconfirming the excellent water solubility of the latter.

Preparation and antibacterial activity of quaternized chitosan with iodine

Chitosan (CTS) is a natural polymer with active groups such as -NH2 which can be functionalized to introduce new positively charged N-atoms and protonated amino group for better use. In this study, to improve the stability of iodine, a novel complex (CTS-CTA-I2) was prepared by mixing N-(2-hydroxy) propyl-3-trimethylammonium chitosan chloride (CTS-CTA) with iodine in ethanol solution. The CTS-CTA-I2 was characterized by Fourier transform infrared spectra (FTIR), Ultraviolet and visible (UV-vis) spectra and thermal gravimetric analysis (TG). Besides, the interaction of iodine with CTS-CTA was also studied. The mole ratio of CTS-CTA with iodine was measured by iodometric titration method and the max mole ratio of CTS-CTA with iodine was 1:1.33. The antimicrobial activity of CTS, CTS-CTA and CTS-CTS-I2 complexes was investigated against Escherichia coli and Staphylococcus aureus and the antibacterial property of CTS-CTA-I2 was superior to CTS-CTA.

Developmental regulation of antioxidant enzymes and their impact on neonatal lung disease

SIGNIFICANCE

Deficient antioxidant defenses and compromised ability to respond to oxidative stress burden the immature lung. Routine neonatal therapies can cause increased oxidative stress with subsequent injury to the premature lung. Novel therapeutic approaches to protect the premature lung are greatly needed.

RECENT ADVANCES

Live cell imaging with targeted redox probes allows for the measurement of subcellular oxidative stress and for comparisons of oxidative stress across development. Comprehension of subcellular and cell-type-specific responses to oxidative stress may influence the targeting of future antioxidant therapies.

CRITICAL ISSUES

Challenges remain in identifying the optimal cellular targets, degree of enzyme activity, and appropriate antioxidant therapy. Further, the efficacy of delivering exogenous antioxidants to specific cell types or subcellular compartments remains under investigation. Treatment with a nonselective antioxidant could unintentionally compromise cellular function or impact cellular defense mechanisms and homeostasis.

FUTURE DIRECTIONS

Genetic and/or biomarker screening may identify infants at the greatest risk for oxidative lung injury and guide the use of more selective antioxidant therapies. Novel approaches to the delivery of antioxidant enzymes may allow cell type- or cellular organelle-specific therapy. Improved comprehension of the antioxidant enzyme regulation across cell type, cell compartment, gender, and developmental stage is critical to the design and optimization of therapy.