Thermosensitive Chitosan-Based Injectable Hydrogel as an Efficient Anticancer Drug Carrier

Prospects of Delivering Natural Compounds by Polymer-Drug Conjugates in Cancer Therapeutics

Synthetic chemotherapeutics have played a crucial role in minimizing mostly palliative symptoms associated with cancer; however, they have also created other problems such as system toxicity due to a lack of specificity. This has led to the development of polymer-drug conjugates amongst other novel drug delivery systems. Most of the formulations designed using delivery systems consist of synthetic drugs and face issues such as drug resistance, which has already rendered drugs such as antibiotics ineffective. This is further exacerbated by toxicity due to long term use. Given these problems and the fact that conjugation of synthetic compounds to polymers has been relatively slow with no formulation on the market after a decade of extensive studies, the focus has shifted to using this platform with medicinal plant extracts to improve solubility, specificity and increase drug release of medicinal and herbal bioactives. In recent years, various plant extracts such as flavonoids, tannins and terpenoids have been studied extensively using this approach. The success of formulations developed using novel drug-delivery systems is highly dependent on the tumour microenvironment especially on the enhanced permeability and retention effect. As a result, the compromised lymphatic network and 'leaky' vasculature exhibited by tumour cells act as a guiding principle in the delivering of these formulations. This review focuses on the state of the polymer-drug conjugates and their exploration with natural compounds, the progress and difficulties thus far, and future directions concerning cancer treatment.

Analysis on Efficacy of Chitosan-Based Gel on Bone Quality and Quantity

Objectives: To assess and compare the quantity and the quality of the newly bone generated when using chitosan-based gel scaffold and osteoprotegerin-chitosan gel scaffold.

Methods: A total of 18 critical-sized defects on New Zealand white rabbit craniums were created. In 12 defects, either chitosan gel or osteoprotegerin-chitosan gel was implanted the last six defects were kept unfilled as a control. Bone formation was examined at 6 and 12 weeks. Bone’s specimens were scanned using the High-resolution peripheral quantitative computed tomography. Histological and histomorphometric analysis were carried out to compare the volume and area of regenerated bone.

Results: The results of the HR-pQCT showed that bone volume and densities in the osteoprotegerin-chitosan gel group were significantly higher than the chitosan gel and control groups whereas, the bone volume density in the chitosan gel group was significantly higher than the control group in both intervals time (p = 0.01, p = 000). No significant difference in bone volume between the chitosan gel and control groups (p = 0.506, p = 0.640) was observed. However, similar findings were shown in the histomorphometric analysis, with the highest new bone formation was observed in the OPG-chitosan gel group followed by the chitosan group. The mean percentage of new bone was greater at 12 weeks compared to 6 weeks in all groups.

Conclusions: Chitosan-based gel demonstrated a significant bone quantity and quality compared to unfilled surgical defects. Consistently, osteoprotegerin enhanced the chitosan gel in bone regeneration.

Why chitosan could be apt candidate for glaucoma drug delivery - An overview

Most of the people in the world are affected by glaucoma, which leads to irreversible blindness. Several patient friendly treatments are available, nevertheless medications lack an easy and efficient way of sustained delivery. To make the delivery with enhanced bioavailability, biodegradable and non-biodegradable polymers-based drug carriers are explored. However, ocular drug delivery issues have not been resolved yet due to less adhesiveness, poor penetration ability, pH, and temperature dependent burst releases. Chitosan is found to be effective for ocular drug delivery due to excellent physio-chemical properties in terms of overcoming the existing issues. In this review, we aim to highlight why it has been chosen and the holy grail for ocular drug delivery. Besides, we have comprehensively reviewed recent patents on chitosan as a platform for ocular drug delivery and future perspectives on factors, lacunae and challenges that need to be addressed for better ocular delivery methods for glaucoma management.

Self-Healing and Injectable Hydrogels for Anticancer Drug Delivery: A Study with Multialdehyde Gum Arabic and Succinic Anhydride Chitosan

Gum arabic with multialdehyde groups (GAMA) was synthesized and utilized as a naturally derived macromolecular and nontoxic cross-linker to develop biocompatible and smart succinic anhydride-modified chitosan (SCS)-based injectable hydrogels for the first time. Aqueous solutions of GAMA and SCS were mixed at 37 °C to obtain hydrogels through pH-responsive, dynamic, and biodegradable Schiff base linkages. The effect of concentration of GAMA on hydrogel stiffness, swelling, morphology, and drug release behavior was investigated. These hydrogels exhibited outstanding self-healing and mechanical properties. Nanocurcumin as a chemotherapeutic agent was synthesized and loaded into these hydrogels for release studies carried out at pH 7.4 and 5.5. MTT assay revealed that these hydrogels are nontoxic to human embryonic kidney cell line (HEK-293). Loaded hydrogels demonstrated significant cytotoxicity against breast cancer cell line (MCF-7). Thus, the present strategy may find promising application for controlled delivery of anticancer drugs for treating locally accessible cancers.