pH responsive release of paclitaxel by self-assembling Chitosan-ethyl vanillin@GNRs nanocomposites

Progress on green crosslinking of polysaccharide hydrogels for drug delivery and tissue engineering applications

Natural polysaccharides are being studied for their biocompatibility, biodegradability, low toxicity, and low cost in the fabrication of various hydrogel devices. However, due to their insufficient physicochemical and mechanical qualities, polysaccharide hydrogels alone are not acceptable for biological applications. Various synthetic crosslinkers have been tested to overcome the drawbacks of standalone polysaccharide hydrogels; however, the presence of toxic residual crosslinkers, the generation of toxic by-products following biodegradation, and the requirement of toxic organic solvents for processing pose challenges in achieving the desired non-toxic biomaterials. Natural crosslinkers such as citric acid, tannic acid, vanillin, gallic acid, ferulic acid, proanthocyanidins, phytic acid, squaric acid, and epigallocatechin have been used to generate polysaccharide-based hydrogels in recent years. Various polysaccharides, including cellulose, alginate, pectin, hyaluronic acid, and chitosan, have been hydrogelized and investigated for their potential in drug delivery and tissue engineering applications using natural crosslinkers. We attempted to provide an overview of the synthesis of polysaccharide-based hydrogel systems (films, complex nanoparticles, microspheres, and porous scaffolds) based on green crosslinkers, as well as a description of the mechanism of crosslinking and properties with a special emphasis on drug delivery, and tissue engineering applications.

Tumor microenvironment-responsive micelles assembled from a prodrug of mitoxantrone and 1-methyl tryptophan for enhanced chemo-immunotherapy

Mitoxantrone (MX) can induce the immunogenic-cell death (ICD) of tumor cells and activate anti-tumor immune responses. However, it can also cause high expression of indole amine 2, 3-dioxygenase (IDO) during ICD, leading to T-cell apoptosis and a weakened immune response. An IDO inhibitor, 1-methyl tryptophan (1-MT), can inhibit the activity of IDO caused by MX, resulting in enhanced chemo-immunotherapy. Here, MX-1-MT was connected by ester bond which could be broken in an acidic tumor microenvironment. MX-1-MT was combined with polyethylene glycol (PEG) via a disulfide bond which could be reduced by glutathione overexpressed in tumors, thereby accelerating drug release at target sites. Folic acid-modified distearoyl phosphoethanolamine-polyethylene glycol (DSPE-PEG-FA) was introduced to form targeting micelles. The micelles were of uniform particle size, high stability, and high responsiveness. They could be taken-up by drug-resistant MCF-7/ADR cells, displayed high targeting ability, and induced enhanced cytotoxicity and ICD. Due to 1-MT addition, micelles could inhibit IDO. In vivo studies demonstrated that micelles could accumulate in the tumor tissues of nude mice, resulting in an enhanced antitumor effect and few side-effects.

Preparation of Self-Assembled, Curcumin-Loaded Nano-Micelles Using Quarternized Chitosan-Vanillin Imine (QCS-Vani Imine) Conjugate and Evaluation of Synergistic Anticancer Effect with Cisplatin

Nano-micelles are self-assembling colloidal dispersions applied to enhance the anticancer efficacy of chemotherapeutic agents. In this study, the conjugate of quarternized chitosan and vanillin imine (QCS-Vani imine) was synthesized using the reaction of a Schiff base characterized by proton-NMR (1HNMR), UV-Vis spectroscopy, and FT-IR. The critical micelle concentration (CMC), particle size, and zeta potential of the resulting product were determined. The QCS-Vani imine conjugate was used as a carrier for the development of curcumin-loaded nano-micelles, and their entrapment efficiency (%EE), drug-loading capacity (%LC) and in vitro release were investigated using HPLC analysis. Moreover, the nano-micelles containing curcumin were combined with various concentrations of cisplatin and evaluated for a possible anticancer synergistic effect. The anticancer activity was evaluated against lung cancer A549 and mouse fibroblast L929 cell lines. The percent yield (%) of the QCS-Vani imine conjugate was 93.18%. The curcumin-loaded QCS-Vani imine nano-micelles were characterized and found to have a spherical shape (by TEM) with size < 200 nm (by DLS) with high %EE up to 67.61% and %LC up to 6.15 ± 0.41%. The loaded lyophilized powder of the nano-micelles was more stable at 4 °C than at room temperature during 120 days of storage. pH-sensitive release properties were observed to have a higher curcumin release at pH 5.5 (cancer environment) than at pH 7.4 (systemic environment). Curcumin-loaded QCS-Vani imine nano-micelles showed higher cytotoxicity and selectivity toward lung cancer A549 cell lines and exhibited lower toxicity toward the normal cell (H9C2) than pure curcumin. Moreover, the curcumin-loaded QCS-Vani imine nano-micelles exhibited an enhanced property of inducing cell cycle arrest during the S-phase against A549 cells and showed prominently induced apoptosis in lung cancer cells compared to that with curcumin. The co-treatment of cisplatin with curcumin-loaded QCS-Vani imine nano-micelles presented an enhanced anticancer effect, showing 8.66 ± 0.88 μM as the IC50 value, in comparison to the treatment with cisplatin alone (14.22 ± 1.01 μM). These findings suggest that the developed QCS-Vani imine nano-micelle is a potential drug delivery system and could be a promising approach for treating lung cancer in combination with cisplatin.

Ethyl Vanillin Rapid Crystallization from Carboxymethyl Chitosan Ion-Switchable Hydrogels

Polymer gels are usually used for crystal growth as the recovered crystals have better properties. Fast crystallization under nanoscale confinement holds great benefits, especially in polymer microgels as its tunable microstructures. This study demonstrated that ethyl vanillin can be quickly crystallized from carboxymethyl chitosan/ethyl vanillin co-mixture gels via classical swift cooling method and supersaturation. It found that EVA appeared with bulk filament crystals accelerated by a large quantity of nanoconfinement microregions resulted from space-formatted hydrogen network between EVA and CMCS when their concentration exceeds 1:1.4 and may occasionally arise when the concentration less than 1:0.8. It was observed that EVA crystal growth has two models involving hang-wall growth at the air-liquid interface at the contact line, as well as extrude-bubble growth at any sites on the liquid surface. Further investigations found that EVA crystals can be recovered from as-prepared ion-switchable CMCS gels by 0.1 M hydrochloric acid or acetic acid without defects. Consequently, the proposed method may offer an available scheme for a large-scale preparation of API analogs.

Lipophilic NO-Driven Nanomotors as Drug Balloon Coating for the Treatment of Atherosclerosis

Drug-coated balloons (DCB) intervention is an important approach for the treatment of atherosclerosis (AS). However, this therapeutic approach has the drawbacks of poor drug retention and penetration at the lesion site. Here, a lipophilic drug-loaded nanomotor as a modified balloon coating for the treatment of AS is reported. First, a lipophilic nanomotor PMA-TPP/PTX loaded with drug PTX and lipophilic triphenylphosphine (TPP) compounds is synthesized. The PMA-TPP/PTX nanomotors use nitric oxide (NO) as the driving force, which is produced from the reaction between arginine on the motor substrate and excess reactive oxygen species (ROS) and inducible nitric oxide synthase (iNOS) in the AS microenvironment. The final in vitro and in vivo experimental results confirm that the introduction of the lipophilic drug-loaded nanomotor technology can greatly enhance the drug retention and permeability in atherosclerotic lesions. In particular, NO can also play an anti-AS role in improving endothelial cell function and reducing oxidative stress. The chemotherapeutic drug PTX loaded onto the nanomotors can inhibit cell division and proliferation, thereby exerting the effect of inhibiting vascular intimal hyperplasia, which is helpful for the multiple therapies of AS. Using nanomotor technology to solve cardiovascular diseases may be a promising research direction.

Scalable Manufacture of Curcumin-Loaded Chitosan Nanocomplex for pH-Responsive Delivery by Coordination-Driven Flash Nanocomplexation

Metal coordination-driven nanocomplexes are known to be responsive to physiologically relevant stimuli such as pH, redox, temperature or light, making them well-suited for antitumor drug delivery. The ever-growing demand for such nanocomplexes necessitates the design of a scalable approach for their production. In this study, we demonstrate a novel coordination self-assembly strategy, termed flash nanocomplexation (FNC), which is rapid and efficient for the fabrication of drug-loaded nanoparticles (NPs) in a continuous manner. Based on this strategy, biocompatible chitosan (CS) and Cu2+ can be regarded anchors to moor the antitumor drug (curcumin, Cur) through coordination, resulting in curcumin-loaded chitosan nanocomplex (Cur-loaded CS nanocomplex) with a narrow size distribution (PDI < 0.124) and high drug loading (up to 41.75%). Owing to the excellent stability of Cur-loaded CS nanocomplex at neutral conditions (>50 days), premature Cur leakage was limited to lower than 1.5%, and pH-responsive drug release behavior was realized in acidic tumor microenvironments. An upscaled manufacture of Cur-loaded CS nanocomplex is demonstrated with continuous FNC, which shows an unprecedented method toward practical applications of nanomedicine for tumor therapy. Furthermore, intracellular uptake study and cytotoxicity experiments toward H1299 cells demonstrates the satisfied anticancer efficacy of the Cur-loaded CS nanocomplex. These results confirm that coordination-driven FNC is an effective method that enables the rapid and scalable fabrication of antitumor drugs.