Design of chondroitin sulfate-based polyelectrolyte nanoplexes: Formation of nanocarriers with chitosan and a case study of salmon calcitonin

Design, optimization and characterization of atorvastatin loaded chitosan-based polyelectrolyte complex nanoparticles based transdermal patch

AIM

Atorvastatin (ATO) loaded chitosan-based polyelectrolyte complex nanoparticles (PECN) incorporated transdermal patch was developed to enhance its skin permeability and bioavailability.

METHODOLOGY

The ATO loaded PECN were prepared by ionic gelation method and optimized by Box-Behnken design. The optimized batches were evaluated for physicochemical characteristics, in vitro, ex vivo, cell line and stability studies. The optimized ATO-PECN were incorporated into transdermal patches by solvent evaporation method and evaluated for their physicochemical properties, ex vivo skin permeation, in vivo pharmacokinetics and stability study.

RESULTS

The optimized batch of ATO-PECN had average size of 219.2 ± 5.98 nm with 82.68 ± 2.63 % entrapment and 25.41 ± 3.29 mV zeta potential. ATO-PECN showed sustained drug release and higher skin permeation. The cell line study showed that ATO-PECN increased the cell permeability of ATO as compared to ATO suspension. ATO-PECN loaded transdermal patch showed higher skin permeation. The in vivo pharmacokinetic study revealed that the ATO-PECN transdermal patch showed significant (p < 0.05) increase in pharmacokinetic parameters as compared to marketed oral tablet, confirming enhancement in bioavailability of ATO.

CONCLUSIONS

The results of the present work concluded that the ATO-PECN loaded transdermal patch is a promising novel drug delivery system for poorly bioavailable drugs.

Injectable Natural Polymer Hydrogels for Treatment of Knee Osteoarthritis

Osteoarthritis (OA) is a serious chronic and degenerative disease that increasingly occurs in the aged population. Its current clinical treatments are limited to symptom relief and cannot regenerate cartilage. Although a better understanding of OA pathophysiology has been facilitating the development of novel therapeutic regimen, delivery of therapeutics to target sites with minimal invasiveness, high retention, and minimal side effects remains a challenge. Biocompatible hydrogels have been recognized to be highly promising for controlled delivery and release of therapeutics and biologics for tissue repair. In this review, the current approaches and the challenges in OA treatment, and unique properties of injectable natural polymer hydrogels as delivery system to overcome the challenges are presented. The common methods for fabrication of injectable polysaccharide-based hydrogels and the effects of their composition and properties on the OA treatment are detailed. The strategies of the use of hydrogels for loading and release cargos are also covered. Finally, recent efforts on the development of injectable polysaccharide-based hydrogels for OA treatment are highlighted, and their current limitations are discussed.

Spatiotemporally controlled calcitonin delivery: Long-term and targeted therapy of skeletal diseases

Bone is a connective tissue that support the entire body and protect the internal organs. However, there are great challenges on curing intractable skeletal diseases such as hypercalcemia, osteoporosis and osteoarthritis. To address these issues, calcitonin (CT) therapy is an effective treatment alternative to regulate calcium metabolism and suppress inflammation response, which are closely related to skeletal diseases. Traditional calcitonin formulation requires frequent administration due to the low bioavailability resulting from the short half-life and abundant calcitonin receptors distributed through the whole body. Therefore, long-term and targeted calcitonin delivery systems (LCDS and TCDS) have been widely explored as the popular strategies to overcome the intrinsic limitations of calcitonin and improve the functions of calcium management and inflammation inhibition in recent years. In this review, we first explain the physiological effects of calcitonin on bone remodeling: (i) inhibitory effects on osteoclasts and (ii) facilitated effects on osteoblasts. Then we summarized four strategies for spatiotemporally controlled delivery of calcitonin: micro-/nanomedicine (e.g. inorganic micro-/nanomedicine, polymeric micro-/nanomedicine and supramolecular assemblies), hydrogels (especially thermosensitive hydrogels), prodrug (PEGylation and targeting design) and hybrid biomaterials. Subsequently, we discussed the application of LCDS and TCDS in treating hypercalcemia, osteoporosis, and arthritis. Understanding and analyzing these advanced calcitonin delivery applications are essential for future development of calcitonin therapies toward skeletal diseases with superior efficacy in clinic.

Development of an in-situ forming, self-healing scaffold for dermal wound healing: in-vitro and in-vivo studies

The importance of the extra-cellular matrix (ECM) for wound healing has been extensively researched. Understanding its importance, multiple ECM mimetic scaffolds have been developed. However, the majority of such scaffolds are prefabricated. Due to their stiffness, prefabricated scaffolds cannot come into direct contact with the basal skin cells at the wound bed, limiting their efficacy. We have developed a unique wound dressing, using chitosan (CH) and chondroitin sulfate (CS), that can form a porous scaffold (CH-CS PEC) in-situ, at the wound site, by simple mixing of the polymer solutions. As CH is positively and CS is negatively charged, mixing these two polymer solutions would lead to electrostatic cross-linking between the polymers, converting them to a porous, viscoelastic scaffold. Owing to the in-situ formation, the scaffold can come in direct contact with the cells at the wound bed, supporting their proliferation and biofunction. In the present study, we confirmed the cross-linked scaffold formation by solid-state NMR, XRD, and TGA analysis. We have demonstrated that the scaffold had a high viscoelastic property, with self-healing capability. Both keratinocyte and fibroblast cells exhibited significantly increased migration and functional markers expression when grown on this scaffold. In the rat skin-excisional wound model, treatment with the in-situ forming CH-CS PEC exhibited enhanced wound healing efficacy. Altogether, this study demonstrated that mixing CH and CS solutions lead to the spontaneous formation of a highly viscoelastic, porous scaffold, which can support epidermal and dermal cell proliferation and bio-function, with an enhanced in-vivo wound healing efficacy.

Developed simvastatin chitosan nanoparticles co-crosslinked with tripolyphosphate and chondroitin sulfate for ASGPR-mediated targeted HCC delivery with enhanced oral bioavailability

Simvastatin (SV) repurposing has emerged as an alternative approach for the treatment of cancer. In this study, SV chitosan nanoparticles co-crosslinked with tripolyphosphate and chondroitin sulfate (SVCSChSNPs) were developed in order to maximize SV therapeutic efficiency. The hepatic targeting was realized using N-acetylgalactosamine (GalNAc) residues of ChS, which can be identified by the ASGPR receptors specifically expressed in hepatocytes. SV was repurposed as an anticancer agent against hepatocellular carcinoma (HCC). NPs were fabricated by the ionic gelation method, and the formulation variables (CS concentration, CS:ChS ratio, and CS solution pH) were optimized using a three-factor, three-level Box-Behnken design. The optimized NPs were investigated for particle size, size distribution, zeta potential, morphology, in vitro cytotoxicity, apoptotic effects against human hepatocellular carcinoma HepG2 cells, and detection of intracellular localization. The NPs were further evaluated for in vitro release behavior of SV and pharmacokinetics using Wister albino rats. Transmission electron microscopy (TEM) imaging showed a spherical shape with regular surface NPs of < 100 nm diameter. In vitro cytotoxicity testing showed that the SVCSChSNPs exhibited greater inhibition of proliferation in HepG2 cells and high cellular uptake through ASGPR-mediated endocytosis. The in vitro dissolution profile was 2.1-fold greater than that of pure SV suspension. Furthermore, in vivo oral pharmacokinetics revealed that the obtained NPs enhanced the bioavailability of SV by up to 2- and 1.6-fold for SV and SVA, respectively, compared to the pure SV suspension. These findings demonstrated that hepatic-targeted CSChSNPs delivering SV could potentially serve as a promising platform for HCC and other liver-related diseases.

Polyelectrolyte-Based Platforms for the Delivery of Peptides and Proteins

The use of peptides and proteins in the pharmaceutical field has increased dramatically over recent years. They have been especially relevant to advances in the treatment of cancer, rheumatoid arthritis, leukemia, and cardiovascular, ophthalmological, metabolic, and infectious diseases. Despite the great potential of peptides and proteins, their use in pharmaceuticals has failed to reach its full potential because of some outstanding challenges. They are unstable under storage conditions and in biological milieus, and their high molecular weight limits permeation through biological membranes. A variety of delivery systems have been investigated to overcome these limitations. Polyelectrolytes (PEs) are molecules that bear multiple negative or positive charges. These molecules play an important role in various platforms relating to the delivery of peptide/protein-based drugs and subunit vaccines. The most commonly utilized PEs include chitosan, alginate, chondroitin sulfate, and poly(γ-glutamic acid). PE-based delivery systems, such as polyelectrolyte complexes (PECs), PE-coated nanocarriers, and PE multilayers, were designed to protect peptides and proteins from degradation and facilitate their absorption. These delivery systems are especially effective when administered orally or intranasally. This review emphasizes the important role of PEs and PE-based delivery vehicles in peptide/protein-based drugs and vaccines.

Black rice anthocyanins embedded in self-assembled chitosan/chondroitin sulfate nanoparticles enhance apoptosis in HCT-116 cells

Self-assembled nanoparticles using the biopolymers chitosan (CH) and chondroitin sulfate (CS) were developed to improve the biological activity of anthocyanin (ACN). The 86.32 ± 0.15% (w/w) of ACN was incorporated into ACN/CH/CS nanoparticles, with the particle size of 350.1 ± 0.99 nm in diameter (i.d.) and 42.55 ± 0.54 in zeta potential (mV). Morphological study and thermogravimetric analysis suggested that the ACN/CH/CS nanoparticles exhibited heterogeneous morphology and high thermal stability. Significant increases in apoptosis by 12.1% and 35.1% were observed with 0.05 mg/ml ACN and ACN/CH/CS nanoparticles in the HCT-116 cell line, indicating that the nanoparticle system led to significant increase in apoptosis (p < 0.05). Structural changes in mitochondria caused by ACN/CH/CS nanoparticles indicated that the nanoparticles had negative impacts on mitochondria. These results showed that nanoparticles could potentially be used as a carrier system to improve the efficacy of ACN.

Chitosan-Chondroitin sulfate based polyelectrolyte complex for effective management of chronic wounds

Acute and chronic wound remain an unresolved clinical problem among various demographic groups. Traditional marketed products focus mainly on inhibition of bacterial growth at the wound site neglecting the tissue repair, which significantly affect the healing rate. It would be highly beneficial if a wound healing material can be developed which has both antibacterial as well as tissue regenerating potential. We have prepared a polyelectrolyte complex (PEC) using chitosan (CH) and chondroitin sulfate (CS) which can form an in-situ scaffold by spontaneous mixing. The fabrication of CH-CS PEC was optimized using Quality-By-Design (QbD) approach. The prepared PEC showed very high swelling and porosity property. It was found to be non-hemolytic with good blood compatibility and low blood clotting index. It also exhibited good antibacterial activity against both gram-positive and gram-negative bacteria. The cell proliferation study exhibited good cytocompatibility and almost four-fold increase in cell density when treated with CH-CS PEC compared to control. In summary, we demonstrated that the prepared CH-CS PEC showed good blood compatibility, high antibacterial effect, and promoted wound healing potentially by stimulating fibroblast growth, making it an ideal wound dressing material.

Folate-targeted nanostructured chitosan/chondroitin sulfate complex carriers for enhanced delivery of bortezomib to colorectal cancer cells

Folate-targeting self-assembled nanoparticles (NPs) using biocompatible and biodegradable natural polymers chitosan (Cs) and chondroitin sulfate (Chs) were developed to address the major challenge in cancer treatment, the selective delivery of nanoparticles to the target site. In this study, we successfully incorporated a hydrophobic drug, bortezomib (Bor), into folic acid (FA)-conjugated Cs/Chs self-assembled NPs (Bor/Cs/Chs-FA) for colorectal cancer therapy. The particle size and polydispersity index of Bor/Cs/Chs-FA were ∼196.5 ± 1.2 nm and ∼0.21 ± 0.5, respectively. A pH-dependent release profile was observed, facilitating cancer cell-targeted drug release under an acidic tumor microenvironment. Moreover, in vitro data revealed enhanced cellular uptake and apoptosis in folate receptor-expressing colorectal cancer cells (HCT-116 and HT-29) as compared to that in lung cancer cells (A549), which do not express folate receptors. Furthermore, intravenous administration of Bor/Cs/Chs-FA in a HCT-116 bearing xenograft mouse model showed that the NPs were a safe and effective drug delivery system. The results suggest that folate-targeted nanoparticle can be effectively applied for efficient chemotherapy of colorectal cancer.

Biodegradable Ingredient-Based Emulgel Loaded with Ketoprofen Nanoparticles

Biodegradable materials are extensively employed to design nanocarriers that mimic extracellular environment in arthritis. The aim of this study was to formulate and characterize biocompatible, biodegradable ketoprofen-loaded chitosan-chondroitin sulfate (CHS-CS) nanoparticles with natural ingredients for transdermal applications. Polymers used in the design of nanocarriers are biodegradable and produce synergistic anti-inflammatory effect for the treatment of arthritis. For transdermal application, argan oil-based emulgel is utilized to impart viscosity to the formulation. Furthermore, naturally occurring argan oil synergizes anti-inflammatory effect of formulation and promotes skin penetration. CHS and CS form nanoparticles by polyelectrolyte complex formation or complex coacervation at pH 5.0. These particles were loaded into argan oil-based emulgel. Employing this method, nanoparticles were formulated with particle size in the range of 300-500 nm. These nanocarriers entrapped ketoprofen and showed more than 76% encapsulation efficiency and 77% release of the ketoprofen at pH 7.4 within 72 h. Drug releases from CHS-CS nanoparticles by mechanism of simple diffusion. Nanoparticle-loaded argan oil emulgel significantly enhanced skin penetration of ketoprofen as compared to marketed gel (p < 0.05). Nanocarriers prepared successfully delivered drug through transdermal route using natural ingredients. Graphical abstract ᅟ.

Polymeric Nanoparticles for Increasing Oral Bioavailability of Curcumin

Despite the promising biological and antioxidant properties of curcumin, its medical applications are limited due to poor solubility in water and low bioavailability. Polymeric nanoparticles (NPs) adapted to oral delivery may overcome these drawbacks. Properties such as particle size, zeta potential, morphology and encapsulation efficiency were assessed. Then, the possibility of storing these NPs in a solid-state form obtained by freeze-drying, in vitro curcumin dissolution and cytocompatibility towards intestinal cells were evaluated. Curcumin-loaded Eudragit^® RLPO (ERL) NPs showed smaller particle diameters (245 ± 2 nm) and better redispersibility after freeze-drying than either poly(lactic-co-glycolic acid) (PLGA) or polycaprolactone (PCL) NPs. The former NPs showed lower curcumin encapsulation efficiency (62%) than either PLGA or PCL NPs (90% and 99%, respectively). Nevertheless, ERL NPs showed rapid curcumin release with 91 ± 5% released over 1 h. The three curcumin-loaded NPs proposed in this work were also compatible with intestinal cells. Overall, ERL NPs are the most promising vehicles for increasing the oral bioavailability of curcumin.

Chitosan Based Self-Assembled Nanoparticles in Drug Delivery

Chitosan is a cationic polysaccharide that is usually obtained by alkaline deacetylation of chitin poly(N-acetylglucosamine). It is biocompatible, biodegradable, mucoadhesive, and non-toxic. These excellent biological properties make chitosan a good candidate for a platform in developing drug delivery systems having improved biodistribution, increased specificity and sensitivity, and reduced pharmacological toxicity. In particular, chitosan nanoparticles are found to be appropriate for non-invasive routes of drug administration: oral, nasal, pulmonary and ocular routes. These applications are facilitated by the absorption-enhancing effect of chitosan. Many procedures for obtaining chitosan nanoparticles have been proposed. Particularly, the introduction of hydrophobic moieties into chitosan molecules by grafting to generate a hydrophobic-hydrophilic balance promoting self-assembly is a current and appealing approach. The grafting agent can be a hydrophobic moiety forming micelles that can entrap lipophilic drugs or it can be the drug itself. Another suitable way to generate self-assembled chitosan nanoparticles is through the formation of polyelectrolyte complexes with polyanions. This paper reviews the main approaches for preparing chitosan nanoparticles by self-assembly through both procedures, and illustrates the state of the art of their application in drug delivery.

Surface active properties of lipid nanocapsules

Lipid nanocapsules (LNCs) are biomimetic nanocarriers used for the encapsulation of a broad variety of active ingredients. Similar to surface active compounds, LNCs contain both hydrophilic and hydrophobic parts in their structure. Moreover, the components of LNCs, macrogol 15 hydroxystearate (MHS) and lecithin, are known for their surface active properties. Therefore, the aim of this paper was to investigate the capability of the LNCs to decrease surface tension using two techniques: drop tensiometry and the Wilhelmy plate method. LNCs with diameters ranging from 30 to 100 nm were successfully obtained using a phase inversion technique. The LNCs' properties, such as size and zeta potential, depend on the composition. LNCs exhibit a lower limiting surface tension compared to MHS (34.8-35.0 mN/m and 37.7-38.8 mN/m, respectively), as confirmed by both drop tensiometry and the Wilhelmy plate method. LNCs have exhibited a saturated interfacial concentration (SIC) that was 10-fold higher than the critical micellar concentration (CMC) of MHS or the SIC of binary and ternary mixtures of LNC ingredients. The SIC of the LNC formulations depended on the mass mixing ratio of the MHS/triglycerides but not on the presence of lecithin. The CMC/SIC values measured by the Wilhelmy plate method were higher than those obtained using drop tensiometry because of the longer duration of the tensiometry measurement. In conclusion, the surfactant-like properties of the LNCs offer new possibilities for medical and pharmaceutical applications.

Synergistic interactions between antimicrobial peptides derived from plectasin and lipid nanocapsules containing monolaurin as a cosurfactant against Staphylococcus aureus

Development of effective antibacterial agents for the treatment of infections caused by Gram-positive bacteria resistant to existing antibiotics, such as methicillin-resistant Staphylococcus aureus (MRSA), is an area of intensive research. In this work, the antibacterial efficacy of two antimicrobial peptides derived from plectasin, AP114 and AP138, used alone and in combination with monolaurin-lipid nanocapsules (ML-LNCs) was evaluated. Several interesting findings emerged from the present study. First, ML-LNCs and both plectasin derivatives showed potent activity against all 14 tested strains of S. aureus, independent of their resistance phenotype. Both peptides displayed a considerable adsorption (33%-62%) onto ML-LNCs without having an important impact on the particle properties such as size. The combinations of peptide with ML-LNC displayed synergistic effect against S. aureus, as confirmed by two methods: checkerboard and time-kill assays. This synergistic interaction enables a dose reduction and consequently decreases the risk of toxicity and has the potential of minimizing the development of resistance. Together, these results suggest that ML-LNCs loaded with a plectasin derivative may be a very promising drug delivery system for further development as a novel antibacterial agent against S. aureus, including MRSA.