Effect of PEGylation on the toxicity and permeability enhancement of chitosan

Potent therapeutic efficacy of intranasally deliverable paclitaxel modified with pH-sensitive and PEGylated polymeric micelle against glioblastoma

Glioblastoma multiforme (GBM) is the most aggressive and common type of brain tumor. Conventional therapies for GBM, such as surgery or radiotherapy, have shown inadequate therapeutic effect. Similarly, a large fraction of chemotherapeutics are ineffective against GBM due to the blood-brain barrier (BBB) preventing effective delivery of these drugs to the brain. To overcome these obstacles, an intranasally administrable and multifunctional drug-loaded polymeric micelle composed of a pH-sensitive PPCBA-PEI-Arg (PPA) polymer conjugated with PEGylated paclitaxel (PEG-PTX; PPP) was synthesized to treat GBM. PPP was more soluble in an aqueous solution than parental PTX and was more effectively internalized into the GBM cells. Further, PPP elicited a more potent cancer cell killing effect than PTX under physiological pH condition, which was further augmented under the mildly acidic condition that emulated the tumor microenvironment. Intranasal administration of PPP into orthotopic GBM tumor xenograft-bearing mice led to more efficient delivery of the drug to the brain tissues compared to parental PTX delivered via intranasal or intravenous route, thus resulting in superior inhibition of GBM growth. Collectively, these findings demonstrated that intranasal delivery of PTX via pH-sensitive and PEGylated polymeric micelles can be an effective approach for the treatment of aggressive GBM.

Harnessing photo-responsive azobenzene-functionalized chitosan nanomicelles for UV protection of photosensitive pesticides

Photosensitive pesticides are susceptible to ultraviolet (UV) light, leading to their easy photodegradation and short half-life under natural conditions. In this context, it is highly desired to develop novel pesticide formulations with UV protection efficiency. In this study, a photo-responsive amphiphilic chitosan-based copolymer (mPEG-CS-AZO) was synthesized successfully by the grafting of poly(ethylene glycol) as the hydrophilic chains, and azobenzene moieties that serve as both hydrophobic and photo-responsive constituents. The mPEG-CS-AZO was characterized with 1H NMR, FTIR, and the critical micelle concentration (CMC) value was determined to be 0.01 mg/mL. mPEG-CS-AZO nanomicelles can be formed spontaneously by the self-assembly in aqueous solution, which were used for the loading of avermectin (AVM), a representative photosensitive pesticide with poor water solubility. The mPEG-CS-AZO nanomicelles can act as UV protector for the loaded AVM, with a retention rate of 57.37 % following 60 h of UV exposure, attributing to that the irradiated UV light can be consumed through the efficient azobenzene trans-cis isomerization. The AVM release profiles fit the first-order model quite well. Therefore, the mPEG-CS-AZO nanomicelles can be applied as potential prospective carriers for photosensitive pesticides with the purpose of UV protective efficiency and sustained release.

Modifying peptide/lipid-associated nucleic acids (PLANAs) for CRISPR/Cas9 ribonucleoprotein delivery

With the first reports on the possibility of genome editing by Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) and CRISPR-associated protein (Cas)9 surfacing in 2005, the enthusiasm for protein silencing via nucleic acid delivery experienced a resurgence following a period of diminished enthusiasm due to challenges in delivering small interfering RNAs (siRNA), especially in vivo. However, delivering the components necessary for this approach into the nucleus is challenging, maybe even more than the cytoplasmic delivery of siRNA. We previously reported the birth of peptide/lipid-associated nucleic acids (PLANAs) for siRNA delivery. This project was designed to investigate the efficiency of these nanoparticles for in vitro delivery of CRISPR/Cas9 ribonucleoproteins. Our initial experiments indicated higher toxicity for PLANAs with the more efficient reverse transfection method. Therefore, polyethylene glycol (PEG) was added to the composition for PEGylation of the nanoparticles by partially replacing two of the lipid components with the PEG-conjugated counterparts. The results indicated a more significant reduction in the toxicity of the nanoparticle, less compromise in encapsulation efficiency and more PEGylation of the surface of the nanoparticles using DOPE-PEG2000 at 50 % replacement of the naïve lipid. The cell internalization and transfection efficiency showed a comparable efficiency for the PEGylated and non-PEGylated PLANAs and the commercially available Lipofectamine™ CRISPRMAX™. Next Generation Sequencing of the cloned cells showed a variety of indels in the transfected cell population. Overall, our results indicate the efficiency and safety of PEGylated PLANAs for in vitro transfection with CRISPR/Cas9 ribonucleoproteins. PEGylation has been studied extensively for in vivo delivery, and PEGylated PLANAs will be candidates for future in vivo studies.

Chitosan-Based Thermogelling System for Nose-to-Brain Donepezil Delivery: Optimising Formulation Properties and Nasal Deposition Profile

Donepezil nasal delivery strategies are being continuously investigated for advancing therapy in Alzheimer's disease. The aim of this study was to develop a chitosan-based, donepezil-loaded thermogelling formulation tailored to meet all the requirements for efficient nose-to-brain delivery. A statistical design of the experiments was implemented for the optimisation of the formulation and/or administration parameters, with regard to formulation viscosity, gelling and spray properties, as well as its targeted nasal deposition within the 3D-printed nasal cavity model. The optimised formulation was further characterised in terms of stability, in vitro release, in vitro biocompatibility and permeability (using Calu-3 cells), ex vivo mucoadhesion (using porcine nasal mucosa), and in vivo irritability (using slug mucosal irritation assay). The applied research design resulted in the development of a sprayable donepezil delivery platform characterised by instant gelation at 34 °C and olfactory deposition reaching a remarkably high 71.8% of the applied dose. The optimised formulation showed prolonged drug release (t_1/2 about 90 min), mucoadhesive behaviour, and reversible permeation enhancement, with a 20-fold increase in adhesion and a 1.5-fold increase in the apparent permeability coefficient in relation to the corresponding donepezil solution. The slug mucosal irritation assay demonstrated an acceptable irritability profile, indicating its potential for safe nasal delivery. It can be concluded that the developed thermogelling formulation showed great promise as an efficient donepezil brain-targeted delivery system. Furthermore, the formulation is worth investigating in vivo for final feasibility confirmation.

L-Cysteine Modified Chitosan Nanoparticles and Carbon-Based Nanostructures for the Intranasal Delivery of Galantamine

The present study evaluates the use of thiolized chitosan conjugates (CS) in combination with two fundamental carbon nanoforms (carbon dots (CDs) and Hierarchical Porous Carbons (HPC)) for the preparation of intranasally (IN) administrated galantamine (GAL) nanoparticles (NPs). Initially, the modification of CS with L-cysteine (Cys) was performed, and the successful formation of a Cys-CS conjugates was verified via ¹H-NMR, FTIR, and pXRD. The new Cys-CS conjugate showed a significant solubility enhancement in neutral and alkaline pH, improving CS’s utility as a matrix-carrier for IN drug administration. In a further step, drug-loaded NPs were prepared via solid-oil–water double emulsification, and thoroughly analyzed by SEM, DLS, FTIR and pXRD. The results showed the formation of spherical NPs with a smooth surface, while the drug was amorphously dispersed within most of the prepared NPs, with the exemption of those systems contianing the CDs. Finally, in vitro dissolution release studies revealed that the prepared NPs could prolong GAL’s release for up to 12 days. In sum, regarding the most promising system, the results of the present study clearly suggest that the preparation of NPs using both Cys-CS and CDs results in a more thermodynamically stable drug dispersion, while a zero-order release profile was achieved, which is essential to attain a stable in vivo pharmacokinetic behavior.

Characterisation of products from EDC-mediated PEG substitution of chitosan allows optimisation of reaction conditions

PEGylation is a common method use to modify the physiochemical properties and increase the solubility of chitosan (CHI). Knowledge of optimal reaction conditions for PEGylation of CHI underpins its ongoing use in nanomedicine. This study synthesised methoxy polyethylene glycol grafted CHI (mPEG-CHI) using carbodiimide-mediated coupling. The effect of reagent concentrations and pH on the degree of substitution (DS) and the PEGylation yield (conversion of free PEG to conjugated PEG) was evaluated through detailed chemical characterisation. Within the parameter space investigated, optimised reaction conditions (NH₂: COOH:NHS:EDC of 3.5:1:1:10, pH = 5) resulted in a DS of 24 % and a PEGylation yield of 84 %. An EDC-derived adduct formed at pH ≥ 5.5 and a at 15-fold excess of EDC relative to COOH. The adduct was evaluated to be a guanidine derivative formed by the reaction of the amine group of CHI directly with EDC. DS ≥ 12 imparted water solubility to CHI at physiological pH and mPEG-CHI (0.2-1.0 mg/mL) was not cytotoxic against the breast cancer cell lines MCF-7 and MDA-MB-231, indicating its suitability for medical applications.

Self-assembled hydrogel nanocube for stimuli responsive drug delivery and tumor ablation by phototherapy against breast cancer

The shape and responsiveness of nanoengineered delivery carriers are crucial characteristics for the rapid and efficient delivery of therapeutics. We report on a novel type of micrometer-sized hydrogel particles of controlled shape with dual pH and redox sensitivity for intracellular delivery of anticancer drugs and phototherapy. The cubical HA-DOP-CS-PEG networks with disulfide links are obtained by cross-linking HA-DOP-CS-PEG with cystamine. The pH-triggered hydrogel swelling/shrinkage was not only affords effective doxorubicin release. It also actively provides the endosomal/lysosomal escape, redox-triggered drug release. The hydrogels degrade rapidly to low molecular weight chains in the presence of the typical intracellular concentration of glutathione. Drug-loaded cube particles found to be 12% more cytotoxic. ICG and DOX-loaded hydrogel cubes demonstrate 90% cytotoxicity when incubated with MCF-7 cancer cells for 24 and 48 h, respectively. This approach integrates the advantages of pH sensitivity, enzymatic degradation, and shape-regulated internalization for novel types of "intelligent" three-dimensional networks with programmable behavior for controlled delivery of therapeutics.

Fabrication and Biological Activities of Plasmid DNA Gene Carrier Nanoparticles Based on Biodegradable l-Tyrosine Polyurethane

Gene therapy is a suitable alternative to chemotherapy due to the complications of drug resistance and toxicity of drugs, and is also known to reduce the occurrence of cellular mutation through the use of gene carriers. In this study, gene carrier nanoparticles with minimal toxicity and high transfection efficiency were fabricated from a biocompatible and biodegradable polymer, l-tyrosine polyurethane (LTU), which was polymerized from presynthesized desaminotyrosyl tyrosine hexyl ester (DTH) and polyethylene glycol (PEG), by using double emulsion and solvent evaporation techniques, resulting in the formation of porous nanoparticles, and then used to evaluate their potential biological activities through molecular controlled release and transfection studies. To assess cellular uptake and transfection efficiency, two model drugs, fluorescently labeled bovine serum albumin (FITC-BSA) and plasmid DNA-linear polyethylenimine (LPEI) complex, were successfully encapsulated in nanoparticles, and their transfection properties and cytotoxicities were evaluated in LX2 as a normal cell and in HepG2 and MCF7 as cancer cells. The morphology and average diameter of the LTU nanoparticles were confirmed using light microscopy, transmission electron microscopy, and dynamic light scattering, while confocal microscopy was used to validate the cellular uptake of FITC-BSA-encapsulated LTU nanoparticles. Moreover, the successful cellular uptake of LTU nanoparticles encapsulated with pDNA-LPEI and the high transfection efficiency, confirmed by gel electrophoresis and X-gal assay transfection, indicated that LTU nanoparticles had excellent cell adsorption ability, facilitated gene encapsulation, and showed the sustained release tendency of genes through transfection experiments, with an optimal concentration ratio of pDNA and LPEI of 1:10. All the above characteristics are ideal for gene carriers designed to transport and release drugs into the cytoplasm, thus facilitating effective gene therapy.

Current trends in chitosan based nanopharmaceuticals for topical vaginal therapies

Large surface area, rich vascularisation, well defined mucous membrane, balanced pH and relatively low enzymatic activity makes vagina a suitable site for drugs associated with women's health issues like Urinary tract infection (UTI) and vaginal infections. Therapeutic performance of intravaginal dosage forms largely depends on the properties of polymers and drugs. Chitosan (CS) because of its unique physical, chemical, pharmaceutical and biopharmaceutical properties have received a great deal of attention as an essential component in vaginal drug delivery systems. Further the presence of free amino and hydroxyl groups on the chitosan skeleton allows easy derivatization under mild conditions to meet specific application requirements. Moreover, CS-based nanopharmaceuticals like nanoparticles, nanofiber, nanogel, nanofilm, liposomes and micelles are widely studied to improve therapeutic performance of vaginal formulations. However, susceptibility of CS to the acidic pH of vagina, poor loading of hydrophobic drugs, rapid mucosal turn over are the key issues need to be addressed for successful outcomes. In this review, we have discussed the application of CS and CS derivatives in vaginal drug delivery and also highlight the recent progress in chitosan based nanocarrier platforms in terms of their limitations and potentials.

Chitosan-Based Biocompatible Copolymers for Thermoresponsive Drug Delivery Systems: On the Development of a Standardization System

Chitosan is a natural polysaccharide that is considered to be biocompatible, biodegradable and non-toxic. The polymer has been used in drug delivery applications for its positive charge, which allows for adhesion with and recognition of biological tissues via non-covalent interactions. In recent times, chitosan has been used for the preparation of graft copolymers with thermoresponsive polymers such as poly-N-vinylcaprolactam (PNVCL) and poly-N-isopropylamide (PNIPAM), allowing the combination of the biodegradability of the natural polymer with the ability to respond to changes in temperature. Due to the growing interest in the utilization of thermoresponsive polymers in the biological context, it is necessary to increase the knowledge of the key principles of thermoresponsivity in order to obtain comparable results between different studies or applications. In the present review, we provide an overview of the basic principles of thermoresponsivity, as well as a description of the main polysaccharides and thermoresponsive materials, with a special focus on chitosan and poly-N-Vinyl caprolactam (PNVCL) and their biomedical applications.

PEG Linker Improves Antitumor Efficacy and Safety of Affibody-Based Drug Conjugates

Antibody drug conjugates (ADCs) have become an important modality of clinical cancer treatment. However, traditional ADCs have some limitations, such as reduced permeability in solid tumors due to the high molecular weight of monoclonal antibodies, difficulty in preparation and heterogeneity of products due to the high drug/antibody ratio (4-8 small molecules per antibody). Miniaturized ADCs may be a potential solution, although their short circulation half-life may lead to new problems. In this study, we propose a novel design strategy for miniaturized ADCs in which drug molecules and small ligand proteins are site-specifically coupled via a bifunctional poly(ethylene glycol) (PEG) chain. The results showed that the inserted PEG chains significantly prolonged the circulation half-life but also obviously reduced the cytotoxicity of the conjugates. Compared with the conjugate Z_HER2-SMCC-MMAE (HM), which has no PEG insertion, Z_HER2-PEG4K-MMAE (HP4KM) and Z_HER2-PEG10K-MMAE (HP10KM) with 4 or 10 kDa PEG insertions have 2.5- and 11.2-fold half-life extensions and 4.5- and 22-fold in vitro cytotoxicity reductions, respectively. The combined effect leads to HP10KM having the most ideal tumor therapeutic ability at the same dosages in the animal model, and its off-target toxicity was also reduced by more than 4 times compared with that of HM. These results may indicate that prolonging the half-life is very helpful in improving the therapeutic capacity of miniaturized ADCs. In the future, the design of better strategies that can prolong half-life without affecting cytotoxicity may be useful for further improving the therapeutic potential of these molecules.

Evaluation of a Product Containing Xyloglucan and Pea Protein on Skin Barrier Permeability

OBJECTIVE

The skin acts as a mechanical and protective barrier against viral, fungal, and bacterial infections. Skin conditions such as atopic dermatitis and psoriasis are characterized by alterations of the skin barrier, often caused by injury and by bacterial infections. In the last years, non-pharmacological interventions have gained great importance in epidermis-related diseases. Xyloglucan (XG) is a polysaccharide that possesses a "mucin-like" molecular structure that confers mucoadhesive properties, allowing XG-containing formulations to act as a protective barrier for the management of different diseases. Moreover, there is also increasing interest in the use of proteins due to their film-forming features. This study aimed to evaluate the barrier-protective properties of a product containing XG and pea protein (PP) in an in vitro model, assessing its effects on the membrane permeability of keratinocytes infected by Staphylococcus aureus.

METHODS

HaCaT keratinocytes were pretreated with XG and PP for 3 h and then infected with S. aureus cells (106 bacteria/well) at a multiplicity of infection of 10 for 1 h. The number of bacterial colonies and membrane integrity were measured, respectively.

RESULTS

We observed that pretreatment with XG and PP in human HaCaT keratinocytes infected with S. aureus significantly increased trans-epithelial electrical resistance (a marker of skin barrier function) measurement, reduced lucifer yellow (a marker of membrane integrity) permeation across the monolayer, and released lactate dehydrogenase (a marker of tissue damage). Moreover, XG and PP pretreatment was able to reduce bacterial adherence, avoiding S. aureus infection.

CONCLUSION

In summary, we demonstrated that the product containing XG and PP was able to maintain barrier permeability preserving its integrity, and therefore, it can be considered as an interesting approach for the management of epidermis-related diseases.

In Vitro and In Vivo Assessment of PEGylated PEI for Anti-IL-8/CxCL-1 siRNA Delivery to the Lungs

Inhalation offers a means of rapid, local delivery of siRNA to treat a range of autoimmune or inflammatory respiratory conditions. This work investigated the potential of a linear 10 kDa Poly(ethylene glycol) (PEG)-modified 25 kDa branched polyethyleneimine (PEI) (PEI-LPEG) to effectively deliver siRNA to airway epithelial cells. Following optimization with anti- glyceraldehyde 3-phosphate dehydrogenase (GAPDH) siRNA, PEI and PEI-LPEG anti-IL8 siRNA nanoparticles were assessed for efficacy using polarised Calu-3 human airway epithelial cells and a twin stage impinger (TSI) in vitro lung model. Studies were then advanced to an in vivo lipopolysaccharide (LPS)-stimulated rodent model of inflammation. In parallel, the suitability of the siRNA-loaded nanoparticles for nebulization using a vibrating mesh nebuliser was assessed. The siRNA nanoparticles were nebulised using an Aerogen^® Pro vibrating mesh nebuliser and characterised for aerosol output, droplet size and fine particle fraction. Only PEI anti-IL8 siRNA nanoparticles were capable of significant levels of IL-8 knockdown in vitro in non-nebulised samples. However, on nebulization through a TSI, only PEI-PEG siRNA nanoparticles demonstrated significant decreases in gene and protein expression in polarised Calu-3 cells. In vivo, both anti-CXCL-1 (rat IL-8 homologue) nanoparticles demonstrated a decreased CXCL-1 gene expression in lung tissue, but this was non-significant. However, PEI anti-CXCL-1 siRNA-treated rats were found to have significantly less infiltrating macrophages in their bronchoalveolar lavage (BAL) fluid. Overall, the in vivo gene and protein inhibition findings indicated a result more reminiscent of the in vitro bolus delivery rather than the in vitro nebulization data. This work demonstrates the potential of nebulised PEI-PEG siRNA nanoparticles in modulating pulmonary inflammation and highlights the need to move towards more relevant in vitro and in vivo models for respiratory drug development.

The Importance of Reaction Conditions on the Chemical Structure of N,O-Acylated Chitosan Derivatives

The structure of acylated chitosan derivatives strongly determines the properties of obtained products, influencing their hydrodynamic properties and thereby their solubility or self-assembly susceptibility. In the present work, the significance of slight changes in acylation conditions on the structure and properties of the products is discussed. A series of chitosan-acylated derivatives was synthesized by varying reaction conditions in a two-step process. As reaction media, two diluted acid solutions-i.e., acetic acid and hydrochloric acid)-and two coupling systems-i.e., 1-ethyl-3-(3-dimethyl-aminopropyl)-1-carbodiimide hydrochloride (EDC) and N-hydroxysulfosuccinimide (EDC/NHS)-were used. The chemical structure of the derivatives was studied in detail by means of two spectroscopic methods, namely infrared and nuclear magnetic resonance spectroscopy, in order to analyze the preference of the systems towards N- or O-acylation reactions, depending on the synthesis conditions used. The results obtained from advanced ¹H-¹³C HMQC spectra emphasized the challenge of achieving a selective acylation reaction path. Additionally, the study of the molecular weight and solution behavior of the derivatives revealed that even slight changes in their chemical structure have an important influence on their final properties. Therefore, an exact knowledge of the obtained structure of derivatives is essential to achieve reaction reproducibility and to target the application.

Natural Polysaccharides for siRNA Delivery: Nanocarriers Based on Chitosan, Hyaluronic Acid, and Their Derivatives

Natural polysaccharides are frequently used in the design of drug delivery systems due to their biocompatibility, biodegradability, and low toxicity. Moreover, they are diverse in structure, size, and charge, and their chemical functional groups can be easily modified to match the needs of the final application and mode of administration. This review focuses on polysaccharidic nanocarriers based on chitosan and hyaluronic acid for small interfering RNA (siRNA) delivery, which are highly positively and negatively charged, respectively. The key properties, strengths, and drawbacks of each polysaccharide are discussed. In addition, their use as efficient nanodelivery systems for gene silencing applications is put into context using the most recent examples from the literature. The latest advances in this field illustrate effectively how chitosan and hyaluronic acid can be modified or associated with other molecules in order to overcome their limitations to produce optimized siRNA delivery systems with promising in vitro and in vivo results.

Chemistry Routes for Copolymer Synthesis Containing PEG for Targeting, Imaging, and Drug Delivery Purposes

Polyethylene glycol (PEG) is one of the most frequently used polymers for coating nanocarriers to enhance their biocompatibility, hydrophilicity, stability, and biodegradability. PEG is now considered to be among the best biocompatible polymers. It offers sterical hindrance against other nanoparticles and blood components such as opsonin, preventing their macrophage phagocytosis and resulting in a prolonged circulation time in blood stream, consequently a ‘stealth character’ in vivo. Therefore, PEG has a very promising future for the development of current therapeutics and biomedical applications. Moreover, the vast number of molecules that PEG can conjugate with might enhance its ability to have an optimistic perspective for the future. This review will present an update on the chemistry used in the modern conjugation methods for a variety of PEG conjugates, such methods include, but are not limited to, the synthesis of targeting PEG conjugates (i.e., Peptides, Folate, Biotin, Mannose etc.), imaging PEG conjugates (i.e., Coumarin, Near Infrared dyes etc.) and delivery PEG conjugates (i.e., doxorubicin, paclitaxel, and other hydrophobic low molecular weight drugs). Furthermore, the type of nanoparticles carrying those conjugates, along with their biomedical uses, will be briefly discussed.

Delivery of MicroRNAs by Chitosan Nanoparticles to Functionally Alter Macrophage Cholesterol Efflux in Vitro and in Vivo

The prevention and treatment of cardiovascular diseases (CVD) has largely focused on lowering circulating LDL cholesterol, yet a significant burden of atherosclerotic disease remains even when LDL is low. Recently, microRNAs (miRNAs) have emerged as exciting therapeutic targets for cardiovascular disease. miRNAs are small noncoding RNAs that post-transcriptionally regulate gene expression by degradation or translational inhibition of target mRNAs. A number of miRNAs have been found to modulate all stages of atherosclerosis, particularly those that promote the efflux of excess cholesterol from lipid-laden macrophages in the vessel wall to the liver. However, one of the major challenges of miRNA-based therapy is to achieve tissue-specific, efficient, and safe delivery of miRNAs in vivo. We sought to develop chitosan nanoparticles (chNPs) that can deliver functional miRNA mimics to macrophages and to determine if these nanoparticles can alter cholesterol efflux and reverse cholesterol transport in vivo. We developed chNPs with a size range of 150-200 nm via the ionic gelation method using tripolyphosphate (TPP) as a cross-linker. In this method, negatively charged miRNAs were encapsulated in the nanoparticles by ionic interactions with polymeric components. We then optimized the efficiency of intracellular delivery of different formulations of chitosan/TPP/miRNA to mouse macrophages. Using a well-defined miRNA with roles in macrophage cholesterol metabolism, we tested whether chNPs could deliver functional miRNAs to macrophages. We find chNPs can transfer exogenous miR-33 to naïve macrophages and reduce the expression of ABCA1, a potent miR-33 target gene, both in vitro and in vivo, confirming that miRNAs delivered via nanoparticles can escape the endosomal system and function in the RISC complex. Because miR-33 and ABCA1 play a key role in regulating the efflux of cholesterol from macrophages, we also confirmed that macrophages treated with miR-33-loaded chNPs exhibited reduced cholesterol efflux to apolipoprotein A1, further confirming functional delivery of the miRNA. In vivo, mice treated with miR33-chNPs showed decreased reverse cholesterol transport (RCT) to the plasma, liver, and feces. In contrast, when efflux-promoting miRNAs were delivered via chNPs, ABCA1 expression and cholesterol efflux into the RCT pathway were improved. Over all, miRNAs can be efficiently delivered to macrophages via nanoparticles, where they can function to regulate ABCA1 expression and cholesterol efflux, suggesting that these miRNA nanoparticles can be used in vivo to target atherosclerotic lesions.

Scaffolding polymeric biomaterials: Are naturally occurring biological macromolecules more appropriate for tissue engineering?

Nowadays, tissue and organ failures resulted from injury, aging accounts, diseases or other type of damages is one of the most important health problems with an increasing incidence worldwide. Current treatments have limitations including, low graft efficiency, shortage of donor organs, as well as immunological problems. In this context, tissue engineering (TE) was introduced as a novel and versatile approach for restoring tissue/organ function using living cells, scaffold and bioactive (macro-)molecules. Among these, scaffold as a three-dimensional (3D) support material, provide physical and chemical cues for seeding cells and has an essential role in cell missions. Among the wide verity of scaffolding materials, natural or synthetic biopolymers are the most commonly biomaterials mainly due to their unique physicochemical and biological features. In this context, naturally occurring biological macromolecules are particular of interest owing to their low immunogenicity, excellent biocompatibility and cytocompatibility, as well as antigenicity that qualified them as popular choices for scaffolding applications. In this review, we highlighted the potentials of natural and synthetic polymers as scaffolding materials. The properties, advantages, and disadvantages of both polymer types as well as the current status, challenges, and recent progresses regarding the application of them as scaffolding biomaterials are also discussed.

Probing molecular interactions of PEGylated chitosan in aqueous solutions using a surface force apparatus

The effects of contact time, solution pH and PEGylation degree on the non-covalent interaction behavior of chitosan are systematically investigated.

Effects of PEG surface density and chain length on the pharmacokinetics and biodistribution of methotrexate-loaded chitosan nanoparticles

Background

One of the most important aspects of drug delivery is extended nanoparticle (NP) residence time in vivo. Herein, we report a series of methotrexate (MTX)-loaded chito-san (CS) NPs coated with differently sized methoxy polyethylene glycol (mPEG) at different mPEG surface densities.

Materials and methods

MTX was incorporated into NPs (112.8–171.2 nm in diameter) prepared from the resulting mPEG-g-CS. The NPs had a zeta potential of +7.4–35.0 mV and MTX loading efficiency of 17.1%–18.4%. MTX/mPEG-g-CS NPs showed an initial burst release of MTX followed by a sustained-release profile in PBS at pH 7.4.

Results

The in vitro cellular uptake study showed that MTX accumulation in J774A.1 macrophage cells decreased with increasing the mPEG surface density or the mPEG molecular weight. The pharmacokinetic study on Sprague Dawley rats revealed an increase in AUC0–72 h (area under the plasma drug concentration–time curve over a period of 72 hours) with increasing the mPEG surface density or the mPEG molecular weight and a linear correlation between the mPEG surface density and AUC_{0–72 h}.

Conclusion

The biodistribution study on Institute of Cancer Research (ICR) mice revealed that MTX/mPEG-g-CS NPs significantly enhanced blood circulation time in the body and decreased accumulation in liver, spleen, and lung. These results suggest the potential of the mPEG-g-CS NPs as a promising candidate for drug delivery.

Water-soluble substituted chitosan derivatives as technology platform for inhalation delivery of siRNA

Despite research efforts full potential of siRNA-based therapeutics has not yet been fully realized due to a need for suitable, effective delivery formulations. Here, we examine a potential of a new class of water-soluble chitosans as siRNA platform for pulmonary delivery. The system is based on piperazine-substituted chitosans, a material designed to integrate established, safe application of chitosan for mucosal administration with novel properties: the piperazine-substituted chitosans are freely water-soluble at physiological pH, possess low cytotoxicity (no significant reduction in cell viability up to 0.1 mg/ml), and provide efficient incorporation of siRNA into sub-300 nm colloidal complexes (at relatively low polymer/siRNA ratio of 5:1). In vitro, the complexes achieved silencing of a model gene at a level of 40–80%, when tested in a panel of lung epithelial cells. Considering the formulation ‘developability’, there were no significant changes in the complexes’ size and integrity on aerosolisation by microsprayer (PenCentury™) device. Following intratracheal aerolisation, the complexes deposited throughout the lung, although relatively inhomogeneously, as judged from IVIS imaging of the isolated mouse lung (visualizing DY647-siRNA). In vivo data illustrate absence of adverse effects on repeated administration of complexes and significant tumor reduction in atopical lung cancer model in mice. Altogether, the data illustrates potential of substituted chitosan derivatives to be utilized as a safe system for inhalation delivery of siRNA.

Recent advances in oral delivery of biologics: nanomedicine and physical modes of delivery

INTRODUCTION

Research into oral delivery of biologics has a long and rich history but has not produced technologies used in the clinic. The area has evolved in terms of strategies to promote oral biologics delivery from early chemical absorption enhancers to nanomedicine to devices. Continued activity in this area is justifiable considering the remarkable proliferation of biologics.

AREAS COVERED

The article discusses some physiological barriers to oral delivery of biologics, with a special focus on less characterized barriers such as the basement membrane. Recent progress in oral delivery of biologics via nanomedicine is subsequently covered. Finally, the emerging field of device-mediated gastrointestinal delivery of biotherapeutics is discussed

EXPERT OPINION

Oral delivery of biologics is considered a 'panacea' in drug delivery. Almost century-old approaches of utilizing chemical absorption enhancers have not produced clinically translated technologies. Nanomedicine for oral biologics delivery has demonstrated potential, but the field is relatively new, and technologies have not progressed to the clinic. Device-mediated oral biologics delivery (e.g. ultrasound or microneedles) is in its infancy. However, this space is likely to intensify owing to advances in electronics and materials, as well as the challenges and history related to clinical translation of alternative approaches.

Chitosan and Its Derivatives for Application in Mucoadhesive Drug Delivery Systems

Mucoadhesive drug delivery systems are desirable as they can increase the residence time of drugs at the site of absorption/action, provide sustained drug release and minimize the degradation of drugs in various body sites. Chitosan is a cationic polysaccharide that exhibits mucoadhesive properties and it has been widely used in the design of mucoadhesive dosage forms. However, its limited mucoadhesive strength and limited water-solubility at neutral and basic pHs are considered as two major drawbacks of its use. Chemical modification of chitosan has been exploited to tackle these two issues. In this review, we highlight the up-to-date studies involving the synthetic approaches and description of mucoadhesive properties of chitosan and chitosan derivatives. These derivatives include trimethyl chitosan, carboxymethyl chitosan, thiolated chitosan, chitosan-enzyme inhibitors, chitosan-ethylenediaminetetraacetic acid (chitosan-EDTA), half-acetylated chitosan, acrylated chitosan, glycol chitosan, chitosan-catechol, methyl pyrrolidinone-chitosan, cyclodextrin-chitosan and oleoyl-quaternised chitosan. We have particularly focused on the effect of chemical derivatization on the mucoadhesive properties of chitosan. Additionally, other important properties including water-solubility, stability, controlled release, permeation enhancing effect, and in vivo performance are also described.

A strategy for high radioprotective activity via the assembly of the PprI protein with a ROS-sensitive polymeric carrier

A strategy is developed for highly effective radioprotection with the PprI protein using a ROS-sensitive polymeric carrier.

Synthesis and characterization of cystamine conjugated chitosan-SS-mPEG based 5-Fluorouracil loaded polymeric nanoparticles for redox responsive drug release

The principle objective of this study was to develop and characterize redox responsive polymeric nanoparticles (PNPs) as a stimuli responsive drug delivery system. The chitosan-cystamine-methoxy poly(ethylene glycol) (CH-SS-mPEG) copolymer was synthesized by conjugation of cystamine appended chitosan with carboxylic acid-terminated mPEG and characterized by FTIR, ¹H NMR, XRD analysis and colorimetric assay. This copolymer could be formulated as 5-Fluorouracil (5-FU) loaded PNPs and the characteristics of PNPs were evaluated. Moreover, folic acid functionalized PNPs were prepared for folate receptor targeted drug delivery. Drug release studies indicated that the redox sensitive PNPs were stable in physiological condition while quickly releasing 5-FU in the trigger of redox potential due to the cleavage of the disulfide linkages. In contrast, less quantity of drug was released from the reduction insensitive chitosan-g-methoxy poly(ethylene glycol) (CH-g-mPEG) based PNPs under both reduction sensitive and non-reductive conditions. From the cytotoxicity studies, it was evident that 5-FU loaded PNPs had higher toxicity against MCF7 cells when compared to 5-FU free PNPs. Subsequently, cellular uptake studies showed significantly increased internalization of folic acid attached PNPs. In conclusion, the developed PNPs appeared to be of great promise in redox responsive drug release for targeted drug delivery.

Cisplatin-Mediated Formation of Polyampholytic Chitosan Nanoparticles with Attenuated Viscosity and pH-Sensitive Drug Release

Chitosan is a biocompatible natural polysaccharide, which has been employed as a polymeric scaffold for versatile, systemic delivery platforms and for locally injectable gels with temperature-sensitive viscosity modulation. Despite the extensive investigation on the chemical modification strategies, however, most of the chitosan-based delivery platforms have been focused on the encapsulation of hydrophobic drugs, which can be simply adsorbed on the chitosan scaffolds by hydrophobic interaction via the postparticle-formation drug-loading process. Herein, we present the facile formation of a cisplatin-coordinated chitosan nanoplatform by exploiting the divalent metal (Pt^II)-mediated conformational changes of chitosan chains, which allows for the simultaneous drug-loading and nanoparticle formation. To this end, the native chitosan has been chemically modified with short polyethylene glycol and malonic acid as a colloidal stabilizer and a bidentate chelating ligand for Pt^II coordination, respectively. The resulting Pt^II-modified polyampholytic chitosan (Pt^II-MPC) has been self-associated in aqueous media by hydrophobic segregation into a compact nanostructure, which exhibited an attenuated viscosity and pH-sensitive release of Pt^II compounds. Once the cationic drug molecules have been released under mild acidic conditions, the neutralized Pt^II-free MPC undergoes interchain flocculation near the isoelectric point because of the polyampholytic property, possibly allowing for the facilitated endosomal escape during the cellular endocytosis by the known membrane perturbation property of chitosan.

Synthesis and Characterization of PEGylated and Fluorinated Chitosans: Application to the Synthesis of Targeted Nanoparticles for Drug Delivery

To synthesize chitosan nanoparticles (CS NPs), ionic gelation is a very attractive method. It relies on the spontaneous supramolecular assembly of cationic CS with anionic compounds, which leads to nanohydrogels. To extend ionic gelation to functionalized CS, the assessment of CS degree of substitution (DS_CS) is a key step. In this paper, we have developed a hyphenated strategy for functionalized CS characterization, based upon ¹H, DOSY and, when relevant, 1D diffusion-filtered ¹⁹F NMR spectroscopies. For that, we have synthesized two series of water-soluble CS via amidation of CS amino groups with mPEG₂₀₀₀-COOH or fluorinated synthons (TFB-COOH). The aforementioned NMR techniques helped to discriminate between ungrafted and grafted synthons and finally to determine DS_CS. According to DS_CS values, the selection of CS-mPEG₂₀₀₀ or CS-TFB copolymers can be made to obtain, in the presence of hyaluronic acid (HA) and tripolyphosphate (TPP), CS-mPEG₂₀₀₀-TPP/HA or CS-TFB-TPP/HA nanohydrogels suitable for drug delivery.

Peptide hormones and lipopeptides: from self-assembly to therapeutic applications

This review describes the properties and activities of lipopeptides and peptide hormones and how the lipidation of peptide hormones could potentially produce therapeutic agents combating some of the most prevalent diseases and conditions. The self-assembly of these types of molecules is outlined, and how this can impact on bioactivity. Peptide hormones specific to the uptake of food and produced in the gastrointestinal tract are discussed in detail. The advantages of lipidated peptide hormones over natural peptide hormones are summarised, in terms of stability and renal clearance, with potential application as therapeutic agents. © 2017 The Authors Journal of Peptide Science published by European Peptide Society and John Wiley & Sons Ltd.

Cellular internalization and transport of biodegradable polyester dendrimers on a model of the pulmonary epithelium and their formulation in pressurized metered-dose inhalers

The purpose of this study was to evaluate the effect of generation and surface PEGylation of degradable polyester-based dendrimers nanocarriers on their interactions with an in vitro model of the pulmonary epithelium as well as to assess the ability to formulate such carriers in propellant-based, portable oral-inhalation devices to determine their potential for local and systemic delivery of drugs to and through the lungs. Hydroxyl (-OH) terminated polyester dendrimers of generation 3 and 4 (G3, and G4) were synthesized using a divergent approach. G4 was surface-modified with PEG (1,000Da). All dendrimers and their building blocks were determined to be highly compatible with the model pulmonary epithelium, with toxicity profiles much more favorable than non-degradable polyamidoamine dendrimers (PAMAM). The transport of the species from the apical to basolateral side across polarized Calu-3 monolayers showed to be generation and surface-chemistry (PEGylation) dependent. The extent of the transport is modulated by their interaction with the polarized epithelium and their transient opening of the tight junctions. G3 was the one most efficiently internalized by the epithelium, and had a small impact on the integrity of the monolayer. On the other hand, the PEGylated G4 was the one least internalized by the polarized epithelium, and at the same time had a more pronounced transient impact on the cellular junctions, resulting in more efficient transport across the cell monolayer. PEGylation of the dendrimer surface played other roles as well. PEGylation modulated the degradation profile of the dendrimer, slowing the process in a step-wise fashion - first the PEG layer is shed and then the dendrimer starts degrading. PEGylation also helped increase the solvation of the nanocarriers by the hydrofluoroalkane propellant used in pressurized metered-dose inhalers, resulting in formulations with excellent dispersibility and aerosol quality (deep lung deposition of 88.5%), despite their very small geometric diameter. The combined in vitro and formulation performance results shown here demonstrated that degradable, modified polyester dendrimers may serve as a valuable platform that can be tailored to target the lung tissue for treating local diseases, or the circulation, using the lungs as pathway to the bloodstream.

PEGylated chitosan grafted with polyamidoamine-dendron as tumor-targeted magnetic resonance imaging contrast agent

PEGylated chitosan grafted with polyamidoamine-dendron was fabricated as a tumor-targeted mCA and its application was well demonstrated.

Spray-dried mucoadhesives for intravesical drug delivery using N-acetylcysteine- and glutathione-glycol chitosan conjugates

This work describes N-acetylcysteine (NAC)- and glutathione (GSH)-glycol chitosan (GC) polymer conjugates engineered as potential platform useful to formulate micro-(MP) and nano-(NP) particles via spray-drying techniques. These conjugates are mucoadhesive over the range of urine pH, 5.0-7.0, which makes them advantageous for intravesical drug delivery and treatment of local bladder diseases. NAC- and GSH-GC conjugates were generated with a synthetic approach optimizing reaction times and purification in order to minimize the oxidation of thiol groups. In this way, the resulting amount of free thiol groups immobilized per gram of NAC- and GSH-GC conjugates was 6.3 and 3.6mmol, respectively. These polymers were completely characterized by molecular weight, surface sulfur content, solubility at different pH values, substitution and swelling degree. Mucoadhesion properties were evaluated in artificial urine by turbidimetric and zeta (ζ)-potential measurements demonstrating good mucoadhesion properties, in particular for NAC-GC at pH 5.0. Starting from the thiolated polymers, MP and NP were prepared using both the Büchi B-191 and Nano Büchi B-90 spray dryers, respectively. The resulting two formulations were evaluated for yield, size, oxidation of thiol groups and ex-vivo mucoadhesion. The new spray drying technique provided NP of suitable size (<1μm) for catheter administration, low degree of oxidation, and sufficient mucoadhesion property with 9% and 18% of GSH- and NAC-GC based NP retained on pig mucosa bladder after 3h of exposure, respectively.

STATEMENT OF SIGNIFICANCE

The aim of the present study was first to optimize the synthesis of NAC-GC and GSH-GC, and preserve the oxidation state of the thiol moieties by introducing several optimizations of the already reported synthetic procedures that increase the mucoadhesive properties and avoid pH-dependent aggregation. Second, starting from these optimized thiomers, we studied the feasibility of manufacturing MP and NP by spray-drying techniques. The aim of this second step was to produce mucoadhesive drug delivery systems of adequate size for vesical administration by catheter, and comparable mucoadhesive properties with respect to the processed polymers, avoiding thiolic oxidation during the formulation. MP with acceptable size produced by spray-dryer Büchi B-191 were compared with NP made with the apparatus Nano Büchi B-90.

Fine-tuned PEGylation of chitosan to maintain optimal siRNA-nanoplex bioactivity

Polyethylene glycol (PEG) is a widely used modification for drug delivery systems. It reduces undesired interaction with biological components, aggregation of complexes and serves as a hydrophilic linker of ligands for targeted drug delivery. However, PEGylation can also lead to undesired changes in physicochemical characteristics of chitosan/siRNA nanoplexes and hamper gene silencing. To address this conflicting issue, PEG-chitosan copolymers were synthesized with stepwise increasing degrees of PEG substitution (1.5% to 8.0%). Subsequently formed PEG-chitosan/siRNA nanoplexes were characterized physicochemically and biologically. The results showed that small ratios of chitosan PEGylation did not affect nanoplex stability and density. However, higher PEGylation ratios reduced nanoplex size and charge, as well as cell uptake and final siRNA knockdown efficiency. Therefore, we recommend fine-tuning of PEGylation ratios to generate PEG-chitosan/siRNA delivery systems with maximum bioactivity. The degree of PEGylation for chitosan/siRNA nanoplexes should be kept low in order to maintain optimal nanoplex efficiency.

Investigating the role of Pluronic-g-Cationic polyelectrolyte as functional stabilizer for nanocrystals: Impact on Paclitaxel oral bioavailability and tumor growth

Paclitaxel (PTX) is a potent anticancer drug which suffers limitations of extremely low oral bioavailability due to low solubility, rapid metabolism and efflux by P-gp transporters. The main objective of this study was to overcome the limitation of PTX by designing delivery systems that can enhance the absorption using multiple pathways. A novel Pluronic-grafted chitosan (Pl-g-CH) copolymer was developed and employed as a functional stabilizer for nanocrystals (NCs) and hypothesized that it would improve PTX absorption by several mechanisms and pathways. Pl-g-CH was synthesized and characterized using (1)H NMR and then used as a stabilizer during nanocrystal development. To establish our proof of concept the optimized formulation having a particle size 192.7 ± 9.2 nm and zeta potential (+) 38.8 ± 3.12 mV was studied extensively on in vitro Caco-2 model. It was observed that nanocrystals rendered higher PTX accumulation inside the cell than Taxol™. P-gp inhibitory potential of Pl-g-CH was proved by flow cytometry and fluorescence microscopy where the much enhanced fluorescence intensity of Rhodamine 123 (Rho-123, P-gp substrate) was observed in the presence of Pl-g-CH. In addition, a significant decrease in Trans Epithelial Electrical Resistance (TEER) of Caco-2 cell monolayers was observed with nanocrystals as well as with Taxol™ (in the presence of free Pl-g-CH compared to only Taxol™). This supports the role of the stabilizer in reversible opening of tight junctions between cells which can allow paracellular transport of drug. The in vivo results were in complete corroboration with in vitro results. Nanocrystals resulted in much enhanced absorption with 12.6-fold improvement in relative bioavailability to that of Taxol™. Concomitantly efficacy data in B16 F10 murine melanoma model also showed a significant reduction in tumor growth with nanocrystals compared to Taxol™ and control. Based on the results it can be suggested that nanocrystals with functional stabilizers can be a promising approach for the oral delivery of anticancer drugs which are P-gp substrates

STATEMENT OF SIGNIFICANCE

Nanocrystals are currently one of the most explored novel drug delivery systems especially for oral delivery of drugs because of ease in synthesis and high drug loading. But their use is still limited for oral delivery of anticancer drugs which are P-gp substrates. This particular study aims at widening the scope of nanocrystals by using a functional stabilizer which participates in enhancing the oral absorption of anticancer drugs and controlling the tumor growth.

Control of the blood-brain barrier function in cancer cell metastasis

Cerebral metastases are the most common brain neoplasms seen clinically in the adults and comprise more than half of all brain tumours. Actual treatment options for brain metastases that include surgical resection, radiotherapy and chemotherapy are rarely curative, although palliative treatment improves survival and life quality of patients carrying brain-metastatic tumours. Chemotherapy in particular has also shown limited or no activity in brain metastasis of most tumour types. Many chemotherapeutic agents used systemically do not cross the blood-brain barrier (BBB), whereas others may transiently weaken the BBB and allow extravasation of tumour cells from the circulation into the brain parenchyma. Increasing evidence points out that the interaction between the BBB and tumour cells plays a key role for implantation and growth of brain metastases in the central nervous system. The BBB, as the tightest endothelial barrier, prevents both early detection and treatment by creating a privileged microenvironment. Therefore, as observed in several in vivo studies, precise targetting the BBB by a specific transient opening of the structure making it permeable for therapeutic compounds, might potentially help to overcome this difficult clinical problem. Moreover, a better understanding of the molecular features of the BBB, its interrelation with metastatic tumour cells and the elucidation of cellular mechanisms responsible for establishing cerebral metastasis must be clearly outlined in order to promote treatment modalities that particularly involve chemotherapy. This in turn would substantially expand the survival and quality of life of patients with brain metastasis, and potentially increase the remission rate. Therefore, the focus of this review is to summarise the current knowledge on the role and function of the BBB in cancer metastasis.

Dendrimer nanocarriers for transport modulation across models of the pulmonary epithelium

The purpose of this study was to determine the effect of PEGylation on the interaction of poly(amidoamine) (PAMAM) dendrimer nanocarriers (DNCs) with in vitro and in vivo models of the pulmonary epithelium. Generation-3 PAMAM dendrimers with varying surface densities of PEG 1000 Da were synthesized and characterized. The results revealed that the apical to basolateral transport of DNCs across polarized Calu-3 monolayers increases with an increase in PEG surface density. DNC having the greatest number of PEG groups (n = 25) on their surface traversed at a rate 10-fold greater than its non-PEGylated counterpart, in spite of their larger size. This behavior was attributed to a significant reduction in charge density upon PEGylation. We also observed that PEGylation can be used to modulate cellular internalization. The total uptake of PEG-free DNC into polarized Calu-3 monolayers was 12% (w/w) vs 2% (w/w) for that with 25 PEGs. Polarization is also shown to be of great relevance in studying this in vitro model of the lung epithelium. The rate of absorption of DNCs administered to mice lungs increased dramatically when conjugated with 25 PEG groups, thus supporting the in vitro results. The exposure obtained for the DNC with 25PEG was determined to be very high, with peak plasma concentrations reaching 5 μg·mL^–1 within 3 h. The combined in vitro and in vivo results shown here demonstrate that PEGylation can be potentially used to modulate the internalization and transport of DNCs across the pulmonary epithelium. Modified dendrimers thereby may serve as a valuable platform that can be tailored to target the lung tissue for treating local diseases, or the circulation, using the lung as pathway to the bloodstream, for systemic delivery.